Experientia, Vol. 37, pp. 476-478, 1981.
The study investigates the frequency and nature of acrocentric chromosome associations in diploid, aneuploid, and polyploid cells using a human epithelial finite cell line designated as KOS-ROV, derived from the ovarian tissue of a forty-three-year-old female. The researchers observed that over seventy-three percent of the examined metaphases contained formations of two, three, or four associated chromosomes belonging to the D and G groups. When analyzing associations involving exactly two chromosomes, the distribution of D and G chromosomes proved to be nonrandom. Specifically, combinations involving two D chromosomes occurred at a significantly higher frequency than statistically expected, whereas combinations of two G chromosomes appeared at a highly significantly lower frequency. This increased active participation of D group chromosomes was also observed to be highly significant in larger formations involving three or four chromosomes. Overall, the ratio of D to G chromosomes involved in all observed associations was 194 to 74, presenting a highly significant difference from the randomly expected ratio of 161 to 107. Ultimately, the findings confirm that D group chromosomes are more actively involved in these structural associations than G group chromosomes, an observation that the authors suggest might reflect an underlying genetic heterogeneity among different chromosome satellites and could be influenced by the specific type of tissue analyzed.
Experientia, Vol. 39, pp. 1394-1395, 1983.
The study investigates the cellular changes that occur when HeLa cells acquire resistance to the drug methotrexate. Researchers developed three distinct methotrexate-resistant HeLa cell lines by gradually increasing the drug's concentration in the culture medium, resulting in lines resistant to one, ten, and one hundred micrograms per milliliter. The analysis revealed that as the level of resistance increased, the cells exhibited a significantly higher production of the enzyme dihydrofolate reductase. In contrast, the parental, drug-sensitive HeLa cells displayed no obvious activity of this enzyme. Additionally, the resistant cell lines consistently contained small, paired acentric chromosomal elements known as double minutes, which were entirely absent in the sensitive parental cells. The presence and quantity of these double minutes correlated with the degree of resistance, with the most highly resistant cells containing an average of eighty-five double minutes per cell. The researchers also evaluated nucleolar organizing region activity using silver staining techniques. They found a profound increase in nucleolar activation in the methotrexate-resistant cells, as evidenced by the greater amount and intensity of silver stain deposited on the chromosomes. Because the actual number of chromosomes carrying active nucleolar organizing regions did not differ significantly between the sensitive and resistant cells, the findings suggest that the existing nucleolar activity was fundamentally amplified in the resistant lines to support the synthesis of large amounts of ribosomal RNA.
Experientia, Vol. 35, Issue 2, pp. 178-179, 1979.
The study presents a rapid, chemical-free method to remove chromatin condensation and induce super-uncoiling in metaphase chromosomes by subjecting cells to simple mechanical vibration. Using Chinese hamster fibroblasts treated with colchicine and a hypotonic solution, researchers found that vibrating the cell suspension for five to sixty seconds prior to fixation successfully disrupted the cellular membrane and completely despiralized the chromosomes. While thirty seconds of vibration produced super-coiled threads forming helices with highly condensed turnings , sixty seconds of vibration, combined with cell lysis, yielded long, thin uncoiled threads displaying dense, dark regions at irregular distances. Prolonged vibration also caused the chromosomes to become extremely glutinous and easily form aggregates. The study suggests that typical metaphase chromosome contraction is maintained by an intrachromosomal system of connective forces, potentially involving perichromosomal fibrils, which the vibration physically disrupts. The presence of irregularly spaced dense regions along the uncoiled arms indicates that standard chromosome spiralization conceals structural details and may influence the banding patterns observed in contracted fixed chromosomes. Ultimately, the author concludes that combining this vibration-induced uncoiling technique with biochemical analysis could offer a valuable new approach for elucidating overall chromosome architecture.
Expl Cell Biol., Vol. 55, Issue 2, pp. 69-73, 1987.
The study investigates the chromosomal abnormalities that emerge during the early developmental stages of methotrexate resistance in HeLa cells. Researchers exposed the cells to gradually increasing concentrations of methotrexate and examined the resulting metaphases two to five days after transferring them to higher drug doses. They discovered that a significantly higher percentage of hypertetraploid cells appeared in populations exposed to doses of 0.5 and 2.1 micrograms per milliliter compared to untreated sensitive cells. These hypertetraploid cells exhibited a profoundly high frequency of dicentric chromosomes at all dose levels above 0.5 micrograms per milliliter, a feature rarely seen in sensitive cells. Additionally, the early stages of resistance were characterized by a high incidence of ring chromosomes, double rings found exclusively in hypertetraploid metaphases, and acentric rod-like fragments that may represent elongated double minutes. Conversely, common abnormalities such as breaks and triradials were less frequent in the resistant cells, indicating that the overproduction of the enzyme dihydrofolate reductase helps these cells escape the drug's clastogenic effects. Ultimately, the high frequency of dicentrics, rings, and acentric fragments during these initial stages suggests that these configurations mediate the production of double minutes and that the cells carrying them act as precursors to the fully resistant cell population.
Med. Oncol. & Tumor Pharmacother., Vol. 2, No. 1, pp. 33-38, 1985.
The study investigates the chromosomal changes that occur in HeLa cells during the initial stages of acquiring resistance to the drug methotrexate. Researchers cultivated these cells in progressively higher concentrations of the drug, ranging from 0.1 to 100.0 micrograms per milliliter, and analyzed the resulting cytogenetic alterations. During the early stages of developing resistance, the cell populations exhibited a significant increase in the percentage of hypertetraploid cells, which are cells containing more than ninety-two chromosomes. This increase in polyploidy was most pronounced at intermediate dose levels of 1.0, 2.1, and 3.0 micrograms per milliliter. At these specific concentrations, the modal chromosome number increased to 82, compared to the baseline of 64 to 66 found in sensitive HeLa cells. Furthermore, the researchers observed a remarkable rise in structural chromosomal abnormalities, notably a high frequency of dicentric chromosomes occurring almost exclusively within the hypertetraploid cell fraction. As the cells were exposed to increasing drug concentrations, there was also a progressive emergence of small, paired chromosomal elements known as double minutes, with the number of these elements per cell rising alongside the dosage. However, as the cells advanced to highly resistant states at 10.0 and 100.0 micrograms per milliliter, the modal chromosome number dropped to 62 or 63, and the frequency of polyploidy and dicentrics decreased, while the number of double minutes reached its peak. Ultimately, the findings indicate that polyploidization and the formation of dicentric chromosomes are characteristic of the early transitional stages of methotrexate resistance, potentially acting as precursors for the surviving cell fractions that eventually develop high numbers of double minutes and secure stable drug resistance.
Differentiation, Vol. 4, pp. 125-134, 1975.
The study investigates the interactions between isolated homologous nuclei and the surface membrane of cultured Chinese hamster fibroblasts under the influence of inactivated Sendai virus. Researchers discovered that the inactivated virus induces a unique, temporary, and temperature-dependent communication between the isolated nuclei and the whole cells, which is fundamentally distinct from typical cellular phagocytosis or permanent cell membrane fusion. Autoradiographic analysis utilizing tritium-labelled nuclei revealed that while no communication occurs at zero degrees Celsius, incubation at thirty-seven degrees Celsius facilitates the direct transfer of small amounts of undegraded genetic material from the isolated nuclei into the recipient cells. The presence of the inactivated Sendai virus significantly enhanced this transfer efficiency, yielding ten to fourteen times more cells exhibiting transferred genetic material compared to experiments lacking the virus. The transferred DNA was initially distributed randomly within the host cell's cytoplasm, but longer incubation periods of five hours showed a more frequent localization of the genetic material within the host cell's nucleus, suggesting an eventual intracellular transport mechanism. Furthermore, control experiments confirmed that this targeted transfer phenomenon is completely independent of the normal, spontaneous rate of DNA excretion from isolated nuclei into the surrounding culture medium. Ultimately, the findings demonstrate that the Sendai virus can mediate the direct, temporary transfer of biologically intact DNA from isolated nuclei into cultured mammalian cells, providing a novel pathway for studying genetic transfer and membrane interactions.
Biochemical Genetics, Vol. 12, No. 2, pp. 147-161, 1974.
The study presents a novel, simple method for producing and isolating hybrid cells from a fibroblastic Chinese hamster cell line and a mouse lymphoma cell line without the use of selective media or contact with parental cells. This nonselective isolation technique relies on the natural growth characteristics dictated by the hybrid's chromosomal makeup, where hybrids predominantly containing hamster chromosomes adhere to glass surfaces, and those with more mouse chromosomes grow in suspension. Through extensive karyotypic analysis, researchers observed that the glass-adherent hybrids eventually established chromosomal stability, retaining two to four mouse chromosomes alongside no fewer than nineteen hamster chromosomes. When these hybrid clones were analyzed for esterase gene expression, the results demonstrated that the mouse genes responsible for synthesizing various esterases were successfully activated and expressed within the hybrid environment. Furthermore, an examination of the electrophoretic patterns revealed that at least five out of the nine expressed esterase genes were unlinked, indicating they are located on different mouse chromosomes. Ultimately, this method offers a valuable approach for investigating genome interactions and gene-chromosome linkage without the preferential chromosome retention biases typically introduced by selective pressure.
Expl. Cell Biol., Vol. 49, pp. 177-184, 1981.
The study investigates the in vitro interactions between human lymphoblastoid cells and human fibroblastic cells. Researchers co-cultured various Epstein-Barr virus-producer and nonproducer lymphoblastoid lines with finite fibroblast lines derived from normal human breast epidermis, a primary breast tumor, and a metastatic lymph node tumor. They observed that lymphoblastoid cells adhere to the fibroblast layers, forming cellular complexes that can be completely dissociated using trypsin, which suggests the intercellular connection relies on a trypsin-sensitive surface protein. The degree of binding varied significantly depending on the origin and growth phase of the fibroblasts, as well as the type of lymphoblastoid cell. Notably, stromal fibroblasts isolated from the metastatic lymph node exhibited a remarkably higher capacity to bind lymphoblastoid cells compared to fibroblasts from normal epidermis or the primary solid tumor. Additionally, this binding affinity was consistently enhanced when the fibroblasts were interacting during their active logarithmic growth phase rather than in a stationary, confluent state. Epstein-Barr virus-producer lymphoblastoid cells generally demonstrated a higher binding affinity than nonproducer lines. Following a ten-hour interaction period, the physical contact induced nuclear abnormalities in a small percentage of the fibroblastic cells and triggered abnormal cellular divisions in the lymphoblastoid cells. This abnormal division ultimately resulted in the disintegration of the lymphoblastoid cells and the subsequent formation of enucleated structures referred to as mini cells. Parallel experiments using mouse embryonic cells revealed that interaction with lymphoblastoid cells caused extensive cytoplasmic vacuolation, an adverse cellular reaction not observed in the human fibroblast lines. Ultimately, the distinct intercellular affinities and resulting structural changes highlight that fibroblasts can develop highly selective functional surface properties that mediate complex interactions with other cell types, potentially reflecting acquired cellular characteristics associated with processes like tumor metastasis.
Int J Clin Exp Med, Vol. 3, Issue 1, pp. 41-47, 2010.
The study investigates the origins of submucosal invasive colorectal carcinomas by assessing the frequency of high-grade dysplasia and carcinoma in situ within a cohort of ninety-two consecutive colorectal adenomas exhibiting submucosal invasion. Researchers observed that submucosal invasion was present in thirty-nine adenomas with high-grade dysplasia, accounting for forty-two percent, while fifty-three adenomas, or fifty-eight percent, displayed carcinoma in situ, representing a statistically significant difference. To further differentiate these lesions, the authors analyzed forty-nine of these adenomas using a DNA-specific Feulgen reaction and a Ki-67 proliferation marker. The results revealed a marked Feulgen reaction in over ninety-one percent of the evaluated high power fields in adenomas with high-grade dysplasia, whereas none of the fields in adenomas with carcinoma in situ displayed this intense reaction. Similarly, intense Ki-67 expression was recorded in over ninety-eight percent of the high power fields for high-grade dysplasia, compared to a mere one point four percent in those with carcinoma in situ. These findings demonstrate that cells from high-grade dysplasia and carcinoma in situ can be distinguished not only by their morphology but also chemically through their DNA content and immunohistochemically via their apparent cell proliferation rates. Despite the paradox that carcinoma in situ cells exhibit a significant arrest in cell proliferation, the study concludes that submucosal invasion arises from both neoplastic phenotypes. Ultimately, while invasion occurred significantly more frequently in adenomas with carcinoma in situ, the substantial forty-two percent progression rate in those with high-grade dysplasia indicates that both non-invasive lesions possess a similar biological capacity to progress into invasive carcinomas.
Cell Death and Differentiation, Vol. 5, pp. 337-339, 1998.
The article provides a comprehensive summary of the International Conference on Apoptosis, held at the International Institute of Anticancer Research in Athens, Greece, from October 2 to 5, 1997. The conference encompassed a broad interdisciplinary spectrum of apoptosis research, highlighting biochemical mechanisms, cellular and molecular biology, genetic regulation, and the role of apoptosis in cancer therapy. Key biochemical discussions explored how transforming growth factor-beta (TGF-β) triggers apoptosis in transformed cells by downmodulating their endogenous survival factors. Furthermore, presentations emphasized the central role of mitochondria in the apoptotic suicide pathway, demonstrating that a decrease in mitochondrial transmembrane potential releases factors that activate the caspase cascade, thus placing caspase activity downstream of the mitochondrial response. Other notable research findings included the ability of non-steroidal anti-inflammatory drugs to induce apoptosis in colorectal carcinoma cell lines independently of p53 and COX-2 , the identification of a novel tumor suppressor gene, mda-7, capable of restraining cell growth and inducing apoptosis in human melanoma and breast cancer cells , and the use of anti-bcl-2 ribozymes to sensitize hormone-resistant prostate cancer cells to apoptotic agents. The meeting concluded with a consensus that researchers must exercise considerable caution when interpreting in vitro apoptosis results, as evidence from knockout mice indicates substantial redundancy and tissue-specificity within the cellular apoptotic machinery.
Journal of Chromatography, Vol. 85, pp. 162-166, 1973.
The study presents a method for the fractionation of total nucleic acids from cultured mammalian cell lysates using polylysine-coated Kieselguhr columns. Researchers lysed Chinese hamster fibroblasts and mouse lymphoma cells, which had been previously labeled with radioactive precursors for DNA and RNA. The cell lysates were applied to the columns and eluted using a linear sodium chloride gradient. The technique successfully separated different nucleic acid species, with transfer RNA eluting at sodium chloride concentrations of 0.70 to 0.80 molar, ribosomal RNA at 1.00 to 1.10 molar, and DNA at 1.75 to 1.90 molar. Interestingly, a small amount of highly radioactive, newly synthesized RNA consistently co-eluted with the DNA, suggesting a strong association between the two molecules that resists dissociation under these experimental conditions. Analysis further revealed that cellular proteins eluted early alongside the RNA fractions, leaving the subsequent DNA fractions completely free of detectable protein contamination. The authors conclude that this reproducible technique offers a valuable tool for directly preparing nucleic acids from small cell quantities without the need for harsh chemicals like detergents or phenol, making it highly suitable for comparative studies on nucleic acid synthesis, protein interactions, and cellular uptake.
Journal of Chromatography, Vol. 130, pp. 396-398, 1977.
The study demonstrates the application of poly-L-lysine-Kieselguhr column chromatography as an effective method for fractionating small quantities of viral ribonucleic acid. Researchers cultivated Sendai virus labeled with Carbon-14 uracil and utilized pancreatic protease to digest the viral envelope, thereby preventing nucleic acid-binding proteins from interfering with the poly-L-lysine column. The crude viral ribonucleic acid preparation was then applied to a 1.5-gram column and eluted using a linear gradient of 0.4 to 4.0 molar sodium chloride. The analysis revealed that the fractionated Sendai virus ribonucleic acid consistently separated into two distinct peaks: a weaker peak eluting between 0.8 and 1.0 molar sodium chloride, and a stronger peak eluting between 1.4 and 1.6 molar sodium chloride. To confirm the stability of the method, the researchers conducted simultaneous chromatography using both the viral ribonucleic acid and calf thymus deoxyribonucleic acid, finding that the elution profiles and corresponding sodium chloride molarities remained highly stable. The authors highlight several core advantages of this chromatography technique, notably its ability to rapidly process very small samples and its avoidance of harsh chemical reagents like sodium dodecyl sulphate or phenol that might otherwise alter the structure and biological activity of the nucleic acids. Furthermore, the method ensures satisfactory recovery while adequately separating different ribonucleic acid species and deoxyribonucleic acid based on different sodium chloride molarities. Ultimately, the study successfully establishes this technique for viral nucleic acid isolation and reveals two distinct ribonucleic acid fractions within the Sendai virus, pointing to the need for further research to evaluate the specific biological functions and properties of these fractions during viral cell infections and membrane fusion events.
Hum. Hered., Vol. 30, pp. 44-45, 1980.
The study investigates the distribution of haptoglobin types in a group of one hundred and nine Greek patients diagnosed with breast carcinoma. Serum samples obtained from the Hellenic Anticancer Institute were analyzed using horizontal starch-gel electrophoresis to determine the patients' haptoglobin phenotypes. The researchers compared the haptoglobin types of these patients to those of a general Greek control population consisting of six hundred and thirty-six individuals. The analysis revealed a significantly higher frequency of the Hp1 gene among the breast cancer patients compared to the control group. Specifically, this overall increase was exclusively driven by a significantly higher frequency of the haptoglobin 1-1 type, which appeared in sixteen point five percent of the patients compared to only nine point six percent of the general population. While noting that these statistically significant findings require further confirmation due to potential debates regarding the representativeness of the control material, the authors highlight that similar associations have been previously reported between the Hp1 gene and leukemia.
Biology of the Cell, Vol. 50, pp. 9-16, 1984.
The study explores the in vitro interactions between human fibroblastic cells, derived from normal or tumor stroma tissues, and HeLa cells (an epithelial cancer cell line). Researchers observed a pronounced affinity between the two cell types in co-cultures, noting that HeLa cells preferentially adhered to the side edges of the fibroblasts rather than distributing randomly. Furthermore, moving fibroblasts actively oriented themselves around the borders of HeLa colonies but never overlapped or invaded dense HeLa territories. When co-cultured at equal or near-equal ratios, both cell types proliferated normally for up to 48 hours without inhibiting each other's DNA synthesis. However, when fibroblasts were heavily outnumbered by HeLa cells (ratios lower than 1:10) or placed over dense HeLa monolayers, their proliferation ceased, and they were eventually eliminated after serial passaging. Using autoradiography, the researchers demonstrated that while ³H-thymidine incorporated into cellular DNA could not be transferred, ³H-nucleotides derived from ³H-uridine could pass between the heterologous cells in either direction. This transfer required direct cell-to-cell contact through cytoplasmic junctions. Notably, the transfer of labeled nucleotides from fibroblasts to HeLa cells occurred more rapidly and extensively than the transfer from HeLa to fibroblasts, suggesting that HeLa cells may possess a "preferential feeding dependence" to utilize fibroblasts as suppliers of small molecules rather than synthesizing them de novo. Ultimately, this in vitro model provides valuable insights into the dynamics of neoplastic and stromal cell interactions, highlighting complex behaviors of intercellular communication, directional locomotion, and metabolic exchange.
Expl Cell Biol., Vol. 51, pp. 315-321, 1983.
The study describes the development and evaluation of a new tissue culture medium, designated as PRC-1, designed to support the proliferation and prolonged in vitro maintenance of human diploid fibroblasts. Researchers tested the PRC-1 medium on fibroblasts derived from normal, benign, and tumor stromal human tissue specimens. Out of fifty-one tissue specimens tested, twenty-eight successful fibroblastic lines were established. Remarkably, these cell lines exceeded their expected normal in vitro life span, surviving in the PRC-1 medium for periods ranging from seven to twenty-five months and undergoing between nine and ninety-one subcultivations. This prolonged longevity significantly contrasted with control cultures maintained in standard media such as McCoy's 5a, Ham's F12, MEM, and Leibovitz L15, which generally failed to support growth beyond seven months. Despite this extended cultivation, all the fibroblastic cell lines successfully retained their normal diploid chromosomal mode throughout their entire maintenance period. The enhanced performance of the PRC-1 medium is attributed to its specific quantitative composition, which includes adjusted, non-inhibitory concentrations of amino acids, purine and pyrimidine bases, inorganic salts, and other essential biological molecules. Ultimately, the findings suggest that the finite lifespan of cultured human fibroblasts can be significantly extended by fulfilling specific nutritional requirements without altering their fundamental genetic stability.
Expl Cell Biol., Vol. 51, pp. 201-209, 1983.
The study investigates the in vitro growth patterns of twenty-one finite stromal fibroblast-like cell lines derived from malignant, benign, and normal human breast tissue specimens. Researchers successfully established cultures from fifty percent of the surgical specimens, which then proliferated for over seven months. The observations revealed that stromal cells originating from both malignant breast tumors and benign lesions, such as chronic mastitis, exhibited uncontrolled growth patterns characterized by a loss of contact inhibition and significant cell overlapping. This uncontrolled growth manifested in varying degrees, ranging from the development of simple multilayers to the continuous or periodic formation of dense, piling-up cell colonies that grew upward rather than spreading horizontally across the substrate. In sharp contrast, all cell lines derived from normal breast epidermis maintained strict contact inhibition of growth and locomotion, consistently forming tightly packed, parallel monolayers without any overlapping. Despite the uncontrolled growth observed in the tumor-associated and benign lesion-associated fibroblasts, these cells did not exhibit standard features of malignant transformation, such as infinite growth or persistent chromosomal alterations; instead, they retained a normal diploid chromosome mode throughout their cultivation. The authors conclude that the disturbance of growth control mechanisms typically seen in tumor cells in vivo is also reflected in the surrounding non-neoplastic stromal fibroblasts when cultured in vitro. This suggests that the tumor stroma, while not neoplastic itself, is profoundly influenced by the adjacent neoplastic growth or the host's immune response, highlighting the complex and supportive role these connective tissues may play within the tumor microenvironment.
Tumor Biol, Vol. 30, pp. 109-120, 2009.
The review article examines the complex and dual role of stromal fibroblasts in tumour development, questioning whether they primarily promote or impede cancer progression. The tumour stroma, often referred to as "reactive stroma," is a tissue framework consisting of the basement membrane, immune cells, capillaries, extracellular matrix (ECM), and prominently, fibroblasts. Unlike normal fibroblasts that maintain ECM homeostasis and regulate epithelial differentiation, tumour-associated fibroblasts frequently differentiate into myofibroblasts that express alpha-smooth muscle actin, leading to an increased ECM deposition known as desmoplasia. This reactive environment is modulated by a dynamic interplay of molecular signals, including vascular endothelial growth factor (VEGF) for angiogenesis, as well as transforming growth factor-beta (TGF-B) and platelet-derived growth factor (PDGF), which drive the desmoplastic response and promote tumour progression. Additionally, matrix metalloproteinases (MMPs) secreted by these cells degrade the basement membrane to facilitate tumour invasion, while altered expression of cell adhesion molecules, such as an increase in N-cadherin, promotes cancer cell motility and metastasis. Furthermore, fibroblasts act as "sentinel" cells during inflammation; however, when the normal clearance of damaged cells fails, chronic inflammation ensues, creating a microenvironment that helps cancer cells escape immune surveillance and adapt to host tissues. While extensive evidence from co-culture models and clinical observations demonstrates that tumour-derived or senescent fibroblasts strongly stimulate cancer cell proliferation, invasion, and metastasis, the authors highlight alternative findings indicating that normal fibroblasts can actively induce apoptosis and cellular disintegration in adjacent cancer cells during the earliest stages of neoplasia. Consequently, the review argues that the potential role of stromal fibroblasts as an initial host defense mechanism designed to confine and eradicate developing tumours has been largely neglected, emphasizing the critical need for further research into the factors that trigger the transition of the stroma from a protective barrier into a cancer-promoting entity.
Biology of the Cell, Vol. 59, pp. 69-78, 1987.
The study investigates the in vitro interactions and resulting growth patterns when human fibroblasts are cocultured with malignant HeLa cells. Using a finite fibroblastic cell line designated as G-EP, researchers observed that the developmental patterns of these cocultures heavily depend on the initial cell density and the ratio between the two cell types. When cocultivated for extended periods without subculturing but with medium replacement every two days, the interactions occur in two distinct phases. During the first phase, HeLa cells form colonies, and the fibroblasts exhibit active, directional locomotion parallel to the colony edges, effectively surrounding them. This contact leads to an accelerated overgrowth of both cell types at the border sites, resulting in the formation of a dense surrounding bow around the HeLa colonies. Interestingly, if the culture medium is not renewed for six or more days, the HeLa cells can overcome this barrier, overgrowing the fibroblasts to form a new extended zone. Resuming the regular refeeding schedule at this point induces the fibroblasts to gather again, forming a second concentric dense border around the newly expanded HeLa territory. The second phase of the interaction, which typically manifests after ten to twelve days of coculture, is characterized by the profound destruction of the neoplastic cells. The human fibroblasts exert a cytocidal effect, causing extensive nuclear and cytoplasmic fragmentation within the HeLa cells. As the HeLa cells disintegrate, their fragments eventually form structures referred to as "mini cells," a process confirmed by utilizing radioactive and carmine labeling to trace the cellular origins. The authors note that this destructive phenomenon strictly requires direct cell-to-cell contact and emphasizes the critical importance of regular nutritional feeding for the activation of the fibroblasts against the cancer cells. Ultimately, this coculture system provides a valuable in vitro model for understanding the complex dynamics of tumor invasion and highlights the potential defensive role that stromal fibroblasts may play against proliferating malignant epithelial cells.
Anticancer Research, Vol. 35, pp. 1881-1916, 2015.
The study investigates the dynamic in vitro interactions between proliferating human fibroblasts, isolated from both normal and tumor tissues, and HeLa cells over a twenty-day co-culture period. Researchers observed that when provided with adequate nutrient replacement and appropriate cell ratios that allow parallel growth, the two cell types exhibit a profound initial affinity. Fibroblasts actively migrate to encircle the HeLa cell colonies, which triggers enhanced growth for both cell types at their direct contact areas. During this interaction phase, the cells exhibit significant changes in protein expression; both types express carbonic anhydrase, while the surrounding fibroblasts specifically display high levels of non-specific esterases, develop complex argyrophilic projections, and intensely secrete lipid droplets. Concurrently, the HeLa cells begin to express E-cadherin. As the co-culture progresses past the tenth day, the interaction shifts from supportive to antagonistic, marked by the detachment of HeLa cell batches at the colony peripheries and the emergence of multi-nucleated and apoptotic HeLa cells. By the seventeenth day, the fibroblasts begin to show signs of stress, becoming blocked in the G2-M phase of the cell cycle. Ultimately, the co-culture evolves into a competitive battlefield characterized by areas of sparse growth, overwhelming fibroblast overgrowth, and scattered pockets of HeLa cell regrowth. The findings demonstrate that proliferating fibroblasts can become activated against cancer cells, dramatically influencing growth patterns, chromatin features, and cell survival. However, this tumor-suppressive activation strictly requires the fibroblasts to remain in an active proliferative state, as the effect is not observed if they are hindered by contact inhibition or nutrient deprivation.
Anticancer Research, Vol. 7, pp. 1005-1010, 1987.
The key finding discussed is the ability of fibroblasts to destroy HeLa cells under specific conditions. This cytocidal effect requires a low initial cell inoculum to allow for prolonged observation (15-20 days), a high fibroblast-to-HeLa ratio (10:1) to prevent the faster-growing HeLa cells from overgrowing, and vital medium replacement every two days. When these parameters are carefully monitored, the fibroblasts flourish and eventually form a dense surrounding bow (DSB) around the HeLa colonies. If the medium is not renewed, HeLa cells can invade this fibroblast barrier; however, with regular feeding, the fibroblasts actively attack and destroy the HeLa cells, leading to extensive nuclear and cytoplasmic fragmentation. These findings suggest that stromal fibroblasts possess a latent capacity to actively defend against cancer cells.
Aneuploidy, Part B: Induction and Test Systems, pp. 163-167, 1988.
The book chapter explores the role of numerical chromosome changes, or aneuploidy, in tumorigenesis and metastasis, noting that such changes are almost always accompanied by structural chromosomal abnormalities. The author highlights the challenges of cytogenetic oncology, pointing out that analyzing short-term cultured cells can be skewed by selection bias and variable mitotic responses. Nevertheless, analyzing fresh tumor material remains the standard for achieving the most accurate karyotypic representation. Aneuploidy is a defining hallmark of both human and animal tumor cells, marked by extensive variation in chromosome numbers. While a normal diploid karyotype is typically restricted to tumors of lesser malignancy, broader numerical deviations consistently correlate with increasing malignancy and poor clinical outcomes, as evidenced by flow cytometric analyses in cancers such as transitional cell bladder carcinoma. In vivo, karyotypic evolution generally reveals an average increase in chromosome numbers as the malignant disease progresses, a pattern observed in pleural and peritoneal effusions from various cancers. These numerical deviations can drive qualitative changes, such as the mutational activation of oncogenes or the inactivation of regulatory genes, as well as quantitative changes leading to the overproduction of specific cancer-related proteins through gene amplification. Ultimately, while there is no strict rule correlating specific numerical deviations with the exact degree of malignancy, metastatic cells consistently exhibit both a higher ploidy level and greater variation in chromosome numbers, indicating that the most advanced malignancies are associated with the most significant and complex chromosomal changes.
Iatriki, Vol. 55, pp. 481-485, 1989.
The paper provides an overview of cytogenetic alterations, particularly in human breast cancer, emphasizing that the primary event in carcinogenesis is often a chromosomal rearrangement. This involves the dissociation of a chromosomal segment from its regulatory region, leading to the activation of oncogenes and uncontrolled cellular division. The review highlights that breast cancer cell populations are frequently aneuploid, particularly within the triploid range, and that the presence of 100-140 chromosomes, along with structural abnormalities, is associated with a poor prognosis. These structural anomalies include chromosomal fragments, translocations, ring chromosomes, and marker chromosomes, such as homogeneously staining regions (HSR) and double minutes (DM). Double minutes, which are small, spherical, DNA-containing bodies that lack centromeres, have been strongly correlated with gene amplification and drug resistance. While structural anomalies like translocations and HSR are considered specific because they are transmitted to daughter cells, others like fragments and rings are considered non-specific. In breast cancer, chromosomes 1, 6, 7, and 11 are most frequently involved in alterations, with chromosome 1 undergoing translocations and trisomies in nearly all examined cases. However, the study notes that there is no consistent chromosomal translocation found across breast cancer cases. This lack of a persistent translocation suggests two possibilities: either the extensive, observable chromosomal changes occur subsequent to a primary, initiating chromosomal event that originally transformed the cell; or the observed, variable translocations serve to activate oncogenes or their regulatory regions located on distant chromosomes. In the latter scenario, it is plausible that more than one chromosomal region is responsible for the malignant transformation. Ultimately, current chromosome research aims to pinpoint these specific chromosomal segments whose alteration results in the loss of normal growth properties and triggers neoplastic transformation.