Showing papers on "Cancer cell published in 1982"

Tamoxifen and Metabolites in MCF7 Cells: Correlation between Binding to Estrogen Receptor and Inhibition of Cell Growth

Abstract: The binding of [3H]tamoxifen ([3H]Tam), a nonsteroidal antiestrogen, and of 4-[3H]hydroxytamoxifen ([3H]OH-Tam), a metabolite accumulated in vivo in target cell nuclei, was characterized in soluble extracts of human breast cancer MCF7 cells growing in a medium depleted in estrogens. Saturation analysis indicated a much higher affinity for OH-Tam (Kd = 0.15 nM) than for Tam (Kd = 4.8 nM). The binding of [3H]Tam and [3H]estradiol was competitive and mutually exclusive, and the binding site concentration (0.16 to 0.47 pmol/mg total protein) was similar for both ligands, strongly suggesting that antiestrogens were binding to the estrogen receptor (ER) in these cells. The ability of Tam and of some of its metabolites or derivatives to prevent the MCF7 cell growth was found to be correlated with their affinity for ER as determined by direct interaction or by binding competition with [3]estradiol on the uterine and MCF7 cytosol ER. OH-Tam was the highest-affinity compound and was 100-fold more active than Tam. The inhibitions observed were actually due to Tam and OH-Tam, respectively, since we did not detect any significant metabolism of these two labeled compounds by the MCF7 cells. N-desmethyltamoxifen, the other Tam metabolite found in high concentration in human plasma, was as effective as Tam while cis-tamoxifen appeared less effective. Compound E, which has no lateral chain, was the only tested compound having a good affinity for ER and a poor efficiency in preventing cell growth. These results support the hypothesis that antiestrogens control the growth of breast cancer by acting directly on the ER located in cancer cells.

Epidermal growth factor receptors and effect of epidermal growth factor on growth of human breast cancer cells in long-term tissue culture.

Abstract: Epidermal growth factor (EGF) may be important in regulating the proliferation of mammary epithelial cells. In the present study, we examined EGF binding and effect on growth in nine human mammary cell lines. The T-47D, MCF-7, SK-Br-3, AIAb 496, BT-20, and BT-474 tumor cell lines and a cell line (HBL-100) derived from milk exhibited EGF binding; both high (Ka 10(10) M-1)- and low (Ka 10(9) M-1)-affinity sites were detected. The total number of EGF receptors per cell of different cell lines varied from 1.6 X 10(3) sites/cell (for AIAb 496) to 1.5 X 10(6) sites/cell (for BT-20). The two floating cell lines, DU4475 and Lev III, had no detectable EGF binding. Effect of EGF on growth was studied by monitoring cell number and the incorporation of [3H]thymidine into DNA of cells maintained in Dulbecco's modified Eagle's medium supplemented with 0.1% fetal bovine serum. Using these procedures, only T-47D cells were stimulated by EGF at low concentrations (0.1 to 1 ng/ml). At concentrations higher than 10 ng/ml, EGF was inhibitory to varying degrees in most cell lines that contained EGF receptors. The growth of the two floating cell lines that had no detectable EGF binding was unaffected by EGF. Our results show that EGF receptors are not present in all human breast cancer cell lines. There is no apparent correlation between EGF binding and its mitogenic activity in cell lines with EGF receptors. EGF may have biological roles in human breast cancer other than growth regulation.

Synthesis, Retention, and Biological Activity of Methotrexate Polyglutamates in Cultured Human Breast Cancer Cells

Abstract: To determine the pharmacologic importance of methotrexate (MTX) polyglutamates, we examined the formation, retention, and effect of these metabolites in cultured human breast cancer cells. Two cell lines (MCF-7 and ZR-75-B) converted the drug to gamma-polyglutamate derivatives in a dose- and time-dependent reaction. After 24-h incubations with 2 muM MTX, polyglutamates of two to five amino acids in length accounted for 55.4% (51.9 nmol/g) of intracellular drug in the MCF-7 cells and 87.6% (62.4 nmol/g) of drug in ZR-75-B cells. In contrast, MDA-231 cells showed lesser accumulation of MTX, and only 32% (4.06 nmol/g) of the intracellular drug was in the form of polyglutamates, a difference that could only partially be explained by decreased ability of these cells to take up free drug from the medium. When MCF-7 and ZR-75-B cells containing polyglutamates were transferred to drug-free medium for 24 h, 22 and 51% of the total intracellular drug were, respectively, retained in each cell line. The loss of intracellular drug was primarily accounted for by disappearance of parent compound and polyglutamates containing 1-3 additional glutamyl residues. The rates of disappearance from cells decreased with increasing glutamyl chain length. All of the 4-NH(2)-10-CH(3)-PteGlu(5) and 47 and 38% of the 4-NH(2)-10-CH(3)-PteGlu(4) remained in the MCF-7 and ZR-75-B cells, respectively, and could be identified in the cytosol after 24 h in drug-free medium. The retention of MTX polyglutamates in these two cell lines in excess of dihydrofolate reductase binding capacity led to prolonged inhibition of thymidylate synthesis and loss of cell viability after removal of extracellular MTX. After 24-h incubation with 2 muM MTX and an additional 24 h in drug-free medium, [(3)H]deoxyuridine incorporation was still inhibited to 30% of control in the MCF-7 cells and 34.7% of control in ZR-75-B cells; this persistent inhibition was associated with a 30% reduction in cell numbers in each cell line during the 24-h period in drug-free medium. In contrast, [(3)H]deoxyuridine incorporation and cell growth quickly recovered to normal in the MDA-231 cells following removal of 2 muM MTX from the medium after a 24-h incubation. Prolonged inhibition of both thymidylate synthesis and cell growth was observed in this cell line in drug-free medium only after a 24-h incubation with 10 muM MTX, a condition that leads to the synthesis of 11.3 nmol/g of MTX polyglutamates. These studies demonstrate that polyglutamate formation allows a prolonged retention of drug in a noneffluxable form and prolonged inhibition of both thymidylate synthesis and cell growth following removal of extracellular drug.

Identification of lymphocyte subpopulations in human breast cancer tissue and its significance: an immunoperoxidase study with anti-human T- and B-cell sera.

Abstract: Subpopulations of the infiltrating lymphocytes in breast cancer tissue from 31 patients were identified by indirect immunoperoxidase technique with antihuman T- and B-cell sera. In all noncancerous lesions examined (seven cases), B-cells were predominant and T-cells were scarcely found. In contrast, T-cells were predominant in breast cancer tissues (17 in 21 cases). T-cells tended to contact closely with cancer cells or cancer cell nests and accumulated around and in the walls of venules draining the cancer, while B-cells tended to cluster focally apart from cancer cell nests. T-cell infiltration was scanty in scirrhus carcinoma, whereas it was ample in infiltrating papillotubular carcinoma which had a better prognosis. There was a significant reverse correlation between the intensity of the T-cell infiltration and the clinical stages. The intensity of the T cell infiltration was significantly high in patients without lymph node metastasis. These facts suggest the possibility that the infiltrating T-cells in cancer tissue represent host resistance against cancer and that the intensity of the T cell infiltration correlates with the clinical prognosis of the breast cancer patients.

Calcium ions and the control of proliferation in normal and cancer cells

Abstract: Several lines of evidence suggest tha Ca2+ ions control cell proliferation: Ca2+ entry into cytoplasm acts as a general mitogen; serum and serum-replacements induce Ca2+ influx; the Ca2+ concentrations in growth media required to support the proliferation of normal cells are much higher than those required for cancer cells; serum and growth factors reduce the Ca2+ requirements of normal cells; tumour promoters alter Ca2+ fluxes via a mechanism used principally by growth factors. Minor supporting evidence includes the effects of various drugs and viruses, and the behaviour of tumour cell mitochondria and intercellular junctions. It is still not possible to decide exactly where and when inside cells the critical effect of Ca2+ on proliferation occurs, but we discuss at length the practical problems of understanding Ca2+ movements in tissue-culture cells. Carried to its logical conclusion, present evidence suggests that an overridden or bypassed Ca2+ control process may be the key, common determinant of unrestrained proliferation in cancer cells.

Effect of Estradiol on the Ultrastructure of the MCF7 Human Breast Cancer Cells in Culture

Abstract: We have analyzed the effect of estradiol and of two classes of antiestrogens on the morphology of the MCF7 human breast cancer cell line by scanning and transmission electron microscopy. Estradiol progressively increased the number and the length of microvilli at the cell surface. The density of the microvilli network increased between 2 and 11 days of estrogen treatment, while the cells became more globular and less tightly attached to the surface of the dish. Estradiol also progressively transformed cells into secretory cells containing, at Day 2, large, clear mitochondria and, at Day 4, rough endoplasmic reticulum and Golgi complexes. At Day 6, secretory granules (diameter, 0.2 µm), which mainly contained glycoproteins, were first observed in the cytoplasm. By Day 8, they were concentrated at the cell membrane and being liberated into the medium. Larger granules (diameter, 0.8 µm), which probably contained lipids, were observed later (Day 11). Cell cultures in 10% fetal calf serum not treated by charcoal contained secretory granules. The modifications were induced by physiological concentrations of estradiol but not 5α-dihydrotestosterone. Progesterone (10 nm for 8 days) completely inhibited the effect of estradiol on the microvilli and secretory activity. Tamoxifen or hydroxytamoxifen did not induce secretory activity but did alter the cell morphology compared to control cells. The effects of estradiol were observed in other estrogen receptor-positive breast cancer cell lines (ZR 75-1, T 47 D) but not in an estrogen receptornegative cell line (BT 20). This morphological evidence that estrogens modify the cell surface of breast cancer cells in culture and transform them into “secretory cells” complements evidence that they induce the release of a glycoprotein with a molecular weight of ≃50,000 into the culture medium (Cell, 20: 352–362, 1980). (The molecular weight was found first to be 46,000. It seems to be closer to 52,000 in a 10% polyacrylamide gel and by using the NEN-labeled proteins as molecular weight markers.)

Specificity of the Control of Tumor Formation by the Blastocyst

Abstract: An assay to determine the mechanism of regulation of embryonal carcinoma cells by the blastocyst, which is based on a comparison of tumors produced when the cancer cells are cloned alone or after incorporation into blastocysts, was refined by labeling embryonal carcinoma cells with fluorescent microspheres and by following their fate after injection into the blastocysts. Through the use of the new techniques, it was observed that cells of one line of nullipotent embryonal carcinoma were controlled at the 50% level, those from another were not controlled, and those from a multipotent but undifferentiated line were controlled in almost absolute fashion. Single Sarcoma 180 or L1210 leukemia cells were not controlled when injected into the blastocele, but C1300 neuroblastoma cells were partially controlled. None of these tumors have a normal cellular counterpart in the blastocyst, as does embryonal carcinoma, but neurulation follows blastulation by only a few days, so that the neuroblastoma cells may be regulated at that time. Parietal yolk sac carcinoma cells, which have a counterpart in the late blastocyst, were not controlled. On the basis of these data, it is postulated that, if one embryonic field can regulate its closely related cancer, then there may be an embryonic field capable of regulating each carcinoma.

Metastatic inefficiency in mice bearing B16 melanomas

Abstract: When injected iv into mice, the F10 subline of B16 melanoma cells produced significantly more lung tumours over a 3-week period than cells of the F101r-6 subline However, in animals bearing intramuscular tumours produced by these sublines, the high pulmonary-colonization potential of the F10 cells was not realized, and no significant differences in natural pulmonary metastasis formation were observed in animals with untreated primary cancers, even when they progressed to the moribund state Massage of im tumours derived from the two sublines produced no change in metastasis and no changes in the numbers of cancer cells in the blood detectable by bioassay In contrast, massage increased metastasis from tumours derived from an invasive BL6 subline and B16 wild-type cells and, in the case of the wild-type, the numbers of circulating cancer cells In vitro experiments show that blood cells from non-tumour-bearing animals are toxic to both sublines; but less to F10 than to F101r-6 In addition, after iv injection of radiolabelled cells, more of the F10 subline were retained in the lungs of recipients than the F101r-6 In spite of these apparent metastatic advantages of the F10 subline following intravasation, the incidence of natural metastases from im F10 and F101r-6 tumours was similar, suggesting that substantially fewer F10 than F101r-6 cells gained access to the circulation Thus, the higher colonization potential of the F10 cells was not matched by its intravasation potential, since metastatic efficiency is determined by the least efficient step in the metastatic process

Growth responses of rat stomach cancer cells to gastro‐entero‐pancreatic hormones

Abstract: Various hormones and peptides were added to rat stomach cancer cells growing in vitro in a serum-free medium and the cell number was determined by a spectro-photometric method Five gastro-entero-pancreatic hormones or related peptides (tetragastrin, glucagon, secretin, cholecystokinin-pancreozymin and cerulein) significantly increased the number of stomach cancer cells from 15% to 310% of the number of control cells cultivated in a serum-free, hormone-free medium On the other hand, insulin and vasoactive intestinal peptide, and other hormones (thyroxin, epinephrine, hydrocortisone, beta-estradiol, progesterone, testosterone), peptone broth and bovine serum albumin had no significant growth effect All the active substances belong to the two major families of gastro-entero-pancreatic polypeptide hormones, suggesting the existence of hormone receptors at the surface of stomach cancer cells

Methionine dependence in cancer cells - a review.

Abstract: Methionine dependence is a defect found in many cancer cell lines that inhibits their growth in culture when methionine is replaced by its immediate precursor, homocysteine, in the culture medium. Normal cultured cells do not have this defect. This report lists the diverse and large number of animal and human cancer lines that are methionine-dependent, and critically reviews the cell biology and methionine biochemistry of the phenomenon.

Hormonal Regulation of Net DNA Synthesis in MCF-7 Human Breast Cancer Cells in Tissue Culture

Abstract: Estrogens and anti-estrogens have striking effects on growth of target tissues in vivo In order to examine these effects in vitro , experimental methods for the rigorous assessment of rates of net DNA synthesis in tissue culture systems are required The quantitation of DNA synthesis with inorganic [32P]orthophosphate is described The limitations of more conventional [3H]thymidine labeling are illustrated in this hormonally responsive system Estrogen administration increases the specific activity of acid-soluble phosphate and increases net DNA synthesis relative to controls in MCF-7 human breast cancer cells Stimulation is most evident after 36 hr of hormone treatment Conversely, tamoxifen produces substantial inhibition of net DNA synthesis after 36 hr of hormone treatment Thymidine availability modulates the effect of estrogens and anti-estrogens on DNA synthesis and constitutes an independent experimental variable

Tumoricidal effect of macrophages exposed to adriamycin in vivo or in vitro.

Abstract: Peritoneal macrophages from BD IX rats collected 24 hr after an i.p. injection of Adriamycin (10 mg/kg) were cytotoxic to syngeneic cancer cells in culture. In contrast, incubation in vitro in Adriamycin solutions did not evoke tumoricidal activity in peritoneal macrophages, whatever the incubation time (from 1 to 24 hr) and the Adriamycin concentration (from 1 ng to 100 µg/ml). Macrophages incubated with Adriamycin in vitro accumulated the drug in their nuclei, whereas macrophages from animals receiving Adriamycin in vivo accumulated it in cytoplasmic vacuoles. Early observation of peritoneal cells after in vivo exposure to Adriamycin shows that Adriamycin is concentrated in mast cell granules which are released and then phagocytosed by peritoneal macrophages. Mast cells exposed to Adriamycin in vitro can induce macrophages to become cytotoxic. These facts explain the difference between macrophages exposed to Adriamycin in vivo and in vitro . Adriamycin fluorescence appears in nuclei of cancer cells incubated with in vivo -labeled macrophages, suggesting that macrophages can directly transfer the drug into cancer cells and therefore play a role in the Adriamycin antitumor effect.

Immunohistochemical detection of an estrogen-regulated protein by monoclonal antibodies.

Abstract: It has been shown previously that estradiol regulates the synthesis of a M r 24,000 cytosol protein in MCF-7 human breast cancer cells. This protein is an attractive probe to study the mechanisms of estrogen regulation in human breast cancer. We have produced monoclonal antibodies against the M r 24,000 protein which show immunocytochemical localization in the cytoplasm of MCF-7 cells grown as solid tumors in nude mice. They do not react with normal mouse tissue or with MDA-MB- 231 cells, an estrogen receptor-negative cell line. Moreover, the monoclonal antibodies react against certain human breast tumor biopsy samples. These data suggest that the monoclonal antibodies obtained will be useful to detect the estrogen-regulated protein by immunohistochemistry.

Actions of cis-diamminedichloroplatinum on cell surface nucleic acids in cancer cells as determined by cell electrophoresis techniques.

Abstract: Whole-cell electrophoresis determinations, using a null technique to measure a cloud of cells, were made on a variety of tumor cell suspensions in order to examine the charged groups on the cell surfaces. We report here evidence, derived from these measurements, which indicates the presence of nucleic acids on the surfaces of the tumor cells. Cells of the ascitic and solid forms of the Sarcoma 180 mouse tumor, grown in ICR mice, showed a decrease of 10 to 20% in electrophoretic mobility when incubated with nucleases. One variant, S-180, exhibited sensitivity to RNase only; another variant was sensitive to both RNase and DNase, while different tumor lines were shown to be sensitive to DNase only. Treatment of tumorbearing animals with a therapeutic dose of cisplatin resulted in a loss of tumor cell mobility identical to that produced by the nuclease incubations of the control cells. Incubation of the cisplatin-treated tumor cells with nucleases produced no change in mobility. The isoelectric points of these cells were determined and are consistent with the loss of a group with a low pK value, such as the phosphates of RNA and DNA, in both cisplatin-treated cells and nuclease-incubated cells. Using the S-180 tumor sensitive to both RNase and DNase, the rates of the two enzymes were additive, but the mobility decreased to the same level regardless of whether the enzymes were used alone or together. This suggests that both enzymes act on the same site. RNase and DNase immobilized on agarose beads were capable of lowering the mobility of the cells upon incubation, confirming the surface location of these nucleic acid residues. S-180 tumor cells were also placed in a tissue culture medium at 37° for up to 22 hr and were treated in vitro with cisplatin and other metabolic inhibitors. Nucleic acid or protein synthesis inhibitors produced a loss of the cell surface nucleic acids. In another in vitro experiment, the nucleic acids were first removed by nucleases, and, when the cells were incubated at 37°, the nucleic acids reappeared. Disappearance with the inhibitors or reappearance after digestion exhibited a half-time of about 2 hr. Surface nucleic acids were detected by this electrophoresis technique on all of several types of tumor cells but not on any normal cells examined.

Drug and Hormone Sensitivity of Estrogen Receptor-positive and -negative Human Breast Cancer Cells in Vitro

Abstract: A clonogenic assay of long-term breast cancer cell cultures in vitro has been developed to provide a highly reproducible method with which to quantitate tumor cell killing by hormones and/or cytotoxic chemotherapeutic agents. Monolayer cultures of estrogen receptor-positive MCF-7 human breast cancer cells and of estrogen receptor-negative Evsa T cells are harvested by treatment with 0.01% trypsin:0.02% EDTA in Hanks' balanced salt solution. Cell suspensions are treated with drug or hormone in serum-free medium for 1 hr at 37 degrees; treated cells are washed, plated, and cultured for approximately 14 days; and colonies consisting of greater than or equal to 30 cells are counted. Compared to estrogen receptor-positive cells, estrogen receptor-negative cells were 2-fold more sensitive to melphalan but were conversely 1.9-fold more resistant to Adriamycin; these differences were statistically significant (p less than 0.001). Thus, response to cytotoxic chemotherapeutic agents appeared to be independent of estrogen receptor status. For cells treated with diethylstilbestrol, the dose of drug or hormone reducing the surviving cell fraction to 1/e (DO) for estrogen receptor-positive cells was 2.27 nmol/ml, and that for estrogen receptor-negative cells was 2.80 nmol/ml; this difference was not statistically significant. However, with tamoxifen therapy, the DO for estrogen receptor-positive cells was 0.601 nmol/ml, and that for estrogen receptor-negative cells was 3.64 nmol/ml; this 6-fold greater degree of resistance to tamoxifen of estrogen receptor-negative cells was highly significant (p less than 0.001). Treatment of cells for 24 hr with 17 beta-estradiol stimulated proliferation not only of estrogen receptor-positive cells but also of estrogen receptor-negative cells. However, estradiol at concentrations up to 200 microM had no apparent cytocidal activity, as measured by the clonogenic assay. Furthermore, treatment of MCF-7 cells simultaneously with estradiol and either diethylstilbestrol or tamoxifen failed to reverse the cytocidal activity of those two agents. These findings suggest that, in the clonogenic assay described herein, diethylstilbestrol and tamoxifen may kill human breast cancer cells by an independent mechanism of action and that the cytocidal activity of diethylstilbestrol and the proliferative effect of 17 beta-estradiol appear to be independent of estrogen receptor status.

The reversibility of cancer: evidence that malignancy in human hepatoma cells is gamma-linolenic acid deficiency-dependent.

Abstract: Certain metabolic abnormalities are common to all malignant cells, and Horrobin proposed that the underlying cause is the inability of cancer cells to produce prostaglandin E1 (PGE1). This appears to be due to the lack of the enzyme delta-6-desaturase which converts the essential fatty acid, linoleic acid, to gamma-linolenic acid (GLA), from which PGE1 is then synthesized. Our studies strongly support this contention. Addition to GLA to cancer cells, thus bypassing the block in the metabolic pathway, results in very marked, statistically highly significant inhibition of growth, while having no effect at all on normal cells. Our finding of the regression of cancer through such proposed normalization offers preliminary hope for a new effective and harmless approach to the treatment of cancer.

Role of tumor cell membrane-bound serine proteases in tumor-induced target cytolysis.

Abstract: The tumor-induced marrow and red blood cell cytolysis assays have been used to explore the mechanism of cancer cell destruction of normal cells. Previously, we suggested that tumor-induced cytolysis was caused by tumor cell membrane-bound serine proteases. In this study, we have shown that concentrations of the broad-spectrum serine protease inhibitor diisopropylfluorophosphate that did not inhibit tumor cell DNA and protein synthesis completely abrogated tumor-induced red blood cell cytolysis. In addition, tumor cell membranes isolated by differential and sucrose density gradient centrifugation and characterized by electron microscopy and enzyme marker analysis were cytolytic for rat 59Fe-labeled red blood cells. The specific activity expressed as release index (%) per microgram of protein was 1.620 for the tumor cell membrane preparations as compared to 0.002 for intact Walker 256 tumor cells. Tumor cell membranes solubilized in Triton X-100 had activity in the p-toluenesulfonyl-L-arginine methyl ester assay for trypsin-like enzymes and the N-benzoyl-L-tyrosine ethyl ester assay for chymotrypsin-like enzymes. The enzyme activities demonstrated in these assays could be inhibited by N-alpha-p-tosyl-L-lysine chloromethyl ketone HCl and L-1-tosylamide-alpha-phenyl-ethyl chloromethyl ketone, respectively. Using [3H]diisopropylfluorophosphate affinity labeling of the tumor cell membrane proteins followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, we have identified membrane-bound serine protease(s) that appear to be responsible for tumor-induced marrow and red blood cell cytolysis.

Specific cytotoxicity of 16 alpha-[125I]iodoestradiol for estrogen receptor-containing breast cancer cells.

Abstract: We attempted to induce specific killing of estrogen receptor-containing breast cancer cells using estradiol coupled to a high specific activity gamma emitting isotope of iodine. MCF-7 human breast cancer cells were incubated with 16α-[125l]iodoestradiol alone ([125I]E2), or with 16α-[125I]iodoestradiol plus 100-fold excess 17 β-estradiol (E2), and then viably frozen. After 8 weeks, the [125I]E2 exposed cells and the plus E2 exposed cells were 10% and 77% of controls, respectively. When the breast cancer cell line MDA-MB-231 which does not contain estrogen receptors was used, the rate of cell death was similar to the competed MCF-7 cells. When specific cytotoxicity was compared using a cloning technique, nearly a 5 log reduction in surviving cell fraction was seen with [125I]E2, as compared to identical cells treated with [125I]E2 plus competitor. This techniq e shows promise for selecting a population of cells with defects in their estrogen receptor and in studying subcellular hormone interactions.

Retrovirus Lymphomagenesis: Relationship of Normal Immune Receptors to Malignant Cell Proliferation

Abstract: In our view the central lesion in oncogenesis is the sustained, apparently uncontrolled proliferation of malignant cells beyond the regulated number of their normal counterparts. In general, therefore, the properties of cancer cells are most similar to those of the proliferating stem cells of that particular tissue or cell type. Thus in this view malignant cells do not differ in kind from normal cells, but mainly in the size of their proliferative compartments. Given this point of view, it is logical to assume that malignant cells utilize normal mitogenic pathways for their sustained proliferation and that one must look to means by which a particular class of cells controls its proliferation if one wishes to understand how malignancy is controlled in that cell type.

Unusual Androgen Sensitivity of the Androgen-independent Dunning R-3327-G Rat Prostatic Adenocarcinoma: Androgen Effect on Tumor Cell Loss

Abstract: Shessel et al. (Invest. Urol., 17: 529–533, 1980) have reproted previously that the serially transplantable Dunning R-3327-G rat prostatic adenocarcinoma grows faster in intact versus castrated male rats. The present study has demonstrated that this is because the G tumor is composed of androgen-independent but -sensitive prostatic cancer cells. The conclusion that G tumor cells are androgen independent is based upon the observations that these cells are capable of growing following inoculation into castrated male rats and that castration of intact male rats bearing established G tumors induces neither regression of tumor volume nor cessation of the continuous growth of the tumor. The G tumor cells, while being androgen independent, are, however, highly sensitive to androgen for their maximal rate of tumor growth. This androgen sensitivity is demonstrated by the fact that the G tumor cells can be reversibly shifted to a faster or slower growth rate simply by manipulation of the host androgen status. The androgen sensitivity of G tumor growth rate is unusual in that it is not due to androgenic stimulation of cell division but to androgen-induced inhibition of G tumor cell loss ( i.e. , the rate of G tumor cell loss is reduced by over 50% when androgen is present). The androgen sensitivity of G tumor cell loss is also unusual in that, due to the low level of 5 α-reductase activity of the G tumor, the predominant intracellular androgen responsible for this inhibition in untreated intact hosts appears to be testosterone and not dihydrotestosterone (DHT). In castrated rats, however, exogenous treatment with DHT is equally as effective as exogenous testosterone in inhibiting G tumor cell loss. These results suggest that G tumor cells are sensitive to either testosterone or DHT but that in untreated intact hosts little DHT is formed by the tumor cells.

Interferon Effect on Cytotoxicity of Peripheral Blood and Tumor-Associated Lymphocytes Against Human Ovarian Carcinoma Cells

Abstract: A study was done to investigate the tumoricidal activity of peripheral blood lymphocytes (PBL) and tumor-associated lymphoid cells (TAL) against freshly isolated tumor cells in human ovarian carcinoma. TAL and carcinoma cells were purified by density and velocity sedimentation on discontinuous Ficoll-Hypaque gradients and fetal bovine serum. Purified carcinoma cells from 23 ascitic and 3 solid tumors were used as targets in a 4- or a 20-hour 51Cr release assay. K562 cells were used to measure natural killer (NK) activity. Freshly purified ovarian carcinoma cells were relatively resistant to lysis by normal unstimulated PBL. Cytolytic activity of ovarian cancer PBL and TAL did not exceed that of control PBL: Only one PBL preparation had high levels of cytotoxicity (36.2 and 42.9% specific lysis after 4 and 20 hr at an effector-to-target cell ratio of 50:1) against autologous cancer cells but not against allogeneic targets (less than 5% specific lysis). TAL and, to a lesser extent, ovarian cancer PBL showed impaired NK activity against K562 compared to the activity seen in controls. In vitro exposure to partially purified human fibroblast interferon (IFN) (1,000 U/ml for 1-18 hr) augmented NK activity against K562 of PBL and TAL. When ovarian carcinoma cells were used as targets, IFN enhanced the cytotoxicity of normal PBL in a 4- and 20-hour assay; stimulation by IFN was less frequently observed with ovarian cancer PBL and TAL in a 4-hour assay, but after 20 hours effector cells from tumor-bearing subjects showed IFN-boosted cytotoxicity against carcinoma cells similar to the degree of cytotoxicity seen in controls. IFN enhanced the cytotoxicity of PBL and TAL against both autologous and allogeneic carcinoma cells. Thus PBL and TAL are rarely cytotoxic against 51Cr-labeled fresh autologous carcinoma cells, but in vitro exposure to IFN induced low levels of killing of ovarian tumor cells.

Viability of intraperitoneal free cancer cells in patients with gastric cancer.

Abstract: The viability and morphologic changes of intraperitoneal free cancer cells in advanced gastric cancer patients were examined by Giemsa and enzymologic staining and by tritiated thymidine uptake. Although many free cancer cells in the pouch of Douglas showed moderate degeneration, viable, morphologically intact cells were noted, leading to the possibility of their implantation and proliferation in the peritoneum. Serosal cancer cells showed a high degree of viability. In patients undergoing gastric cancer surgery, the viability of free cancer cells was markedly decreased by a single intraoperative administration of 10 mg of mitomycin C (MMC) to the pouch of Douglas, suggesting that this may represent an effective means of preventing peritoneal dissemination.

Clonal analysis of morphological phenotype in cultured mammary epithelial cells from human milk

Abstract: Three main types of colony forming epithelial cell, termed elongated, cuboidal and open, are found in cultures of human milk. Subculture of identified colonies, and cloning from single cells shows that each cell type can maintain its morphological phenotype, but in addition the cuboidal and open cell types can give rise to the elongated type. The results, which suggest a differentiation pathway starting with open cell types, are discussed in relation to differentiation studies on mammary cancer cells.