Upregulation of DF3, in association with ICAM-1 and MHC class II by IFN-gamma in short-term human mammary carcinoma cell cultures.

This study was designed to determine whether in vitro exposure of isolated short-term human primary and metastatic breast tumor cell cultures to interferon-gamma (IFN-gamma) could enhance expression of the breast tumor associated DF3 antigen in association with the intercellular adhesion molecule 1 (ICAM-1) and MHC class II molecules. Cell cultures were established from primary solid tumors and metastatic cells as previously described (Sgagias et al., 1995). Data show that recombinant human IFN-gamma treatment, in vitro, dramatically increased the breast tumor associated DF3 antigen, in association with ICAM-1, and MHC class II antigens in primary breast cancer cell cultures. All primary breast tumor cell cultures constitutively expressed high levels of HLA-class I antigen. Metastatic breast cancer cell cultures expressed high levels of DF3 and recombinant human IFN-gamma treatment, in vitro, upregulated ICAM-1 and MHC class II antigens before and after passage of the metastatic cells through the nude mouse. Metastatic breast cancer cells similar to primary breast cancer cells constitutively expressed high levels of MHC class I antigens. In addition, three LAK cell lines significantly lysed the primary and the metastatic breast tumor cell cultures to the same degree before and after passage of the metastatic cancer cells through the nude mouse. These data indicate the upregulation of the breast tumor associated DF3 antigen in vitro after IFN-gamma treatment and its persistence in vivo, after passage of the metastatic breast cancer cells through the nude mouse. The ability of IFN-gamma to upregulate the breast tumor associated DF3 antigen in association with the ICAM-1 and HLA class II antigens may play an important role in eliciting an immune response which may contribute to the immunodiagnosis, and immunotherapy of breast cancer.

Tumor necrosis factor alpha enhances secretion of transforming growth factor beta2 in MCF-7 breast cancer cells.

We studied the effect of tumor necrosis factor alpha (TNF-alpha) on transforming growth factor beta (TGF-beta) secretion by human breast cell lines to further characterize the antitumor effects of TNF-alpha. We found that TNF-alpha increased the secretion of TGF-beta in two established breast cancer cell lines (MCF-7 and ZR-75-1) but not in two immortalized human mammary epithelial cell lines (184B5 and MCF-10A). In MCF-7 cells, TNF-alpha increased the secretion of total TGF-beta 6.1-fold within 72 h in a dose-dependent manner. The secretion of both latent and active forms of TGF-beta was increased, and their ratio altered from 25:1 to 12:1 in the medium. TNF-alpha converted the secretory pattern of TGF-beta by MCF-7 cells from the heterodimeric form TGF-beta1.2 to the homodimeric form TGF-beta2. Immunoblot analysis under nonreducing conditions identified four molecular mass species of TGF-beta secreted in the culture media of untreated MCF-7 cells (238, 210, 40-55, and 25 kDa). Under reducing conditions, three molecular mass species of TGF-beta were identified: 88, 44, and 12 kDa. Gel filtration analysis demonstrated that the secreted TGF-beta within the range of 12-88 kDa was biologically active. TNF-alpha treatment did not alter the size of molecular mass species secreted by MCF-7 cells and did not change steady-state levels of mRNA for TGF-beta1 or TGF-beta2. These findings indicate that TNF-alpha may regulate quantitatively and qualitatively TGF-beta secretion by human breast cancer cells in vitro. The diverse biological activities of TGF-beta may also allow TNF-alpha to regulate the growth and metabolism of human mammary epithelial cells and/or stromal cells in a paracrine manner.

Interleukin 6 acts as a paracrine growth factor in human mammary carcinoma cell lines.

The effect of interleukin 6 (IL-6) on normal and human mammary carcinoma epithelial cells was studied. IL-6 inhibited the growth of estrogen receptor-positive [ER(+)] breast cancer cell lines, which underwent apoptosis with prolonged treatment. In contrast, ER(-) breast cancer cell lines were resistant to IL-6-mediated growth inhibition. By examining the components of the IL-6 receptor (IL-6R) system, we found that ER(+) breast cancer cells expressed predominantly soluble IL-6Ralpha, whereas the ER(-) breast cancer cells expressed primarily the transmembrane form of the IL-6R, gp130. In addition, detectable levels of IL-6 were secreted into the medium by ER(-) but not ER(+) breast cancer cells. Furthermore, the supernatant obtained from IL-6-secreting, ER(-) cells suppressed the growth of IL-6-sensitive, ER(+) breast cancer cells in a paracrine fashion. Although IL-6 is secreted by ER(-) breast cancer cells, this cytokine does not seem to stimulate the proliferation of these cells in an autocrine fashion. These studies indicate that IL-6 can regulate the growth of normal and transformed human mammary epithelial cells differentially, and that IL-6 secretion by some ER(-) breast cancer cells can function as a paracrine growth factor, suppressing the growth of ER(+) breast cancer cells in vitro.

Isolation of a gene encoding a human reduced folate carrier (RFC1) and analysis of its expression in transport-deficient, methotrexate-resistant human breast cancer cells.

Our laboratory has previously reported the isolation of a murine cDNA which restores reduced folate carrier (RFC) activity and methotrexate (MTX) sensitivity to a MTX-resistant, transport-deficient human breast cancer cell line (MTXR ZR-75-1) (K. H. Dixon et al., J. Biol. Chem., 269: 17-20, 1994). Using this murine cDNA as a probe, we have isolated two homologous overlapping partial cDNAs from a human testis cDNA library. In addition, using human cDNA as a probe, we have isolated a 20-kb human genomic fragment which contains RFC coding regions. Analysis of the nucleotide sequence of these clones revealed that the human RFC gene, RFC1, is approximately 65% homologous to the murine and hamster genes. Using a human genomic P1 plasmid clone containing RFC1, we mapped the location of RFC1 by fluorescence in situ hybridization to the end of the long arm of chromosome 21 (21q22.2-q22.3). Fluorescence in situ hybridization analysis also showed that two copies of RFC1 were present in MTXR ZR-75-1 cells, and showed no evidence of rearrangement of this gene. Northern blot analysis of MTXR ZR-75-1 cells demonstrated a marked decrease in the level of the 3-kb RFC1 transcript relative to the parental cell line, and Western blot analysis using a polyclonal antibody raised against a peptide generated from the RFC1 sequence showed decreased expression of an approximately M(r) 56,000 protein in MTXR ZR-75-1 cells. Finally, MTXR ZR-75-1 cells transfected with an RFC1 gene showed increased MTX uptake, which was more sensitive to competition by folinic acid than by folic acid. Therefore, decreased RFC1 expression appears to be the molecular mechanism of decreased MTX uptake in this MTX-resistant cell line.

Cellular characterization and retroviral transduction of short-term breast cancer cells.

The effort to develop cell lines from surgical specimens has been a difficult goal for years. We derived short-term primary human mammary carcinoma cell lines from breast tumors in 20 of 23 patients. Morphologically, cultured cells showed small cells with high nuclear cytoplasmic ratio and larger cells with abundant dense cytoplasm. The nuclei were round to oval with one to four nucleoli. Immunocytochemically, the cells stained positive for keratin. Tumor cells showed phenotypic overexpression of the breast tumor-associated antigen DF3 compared with normal mammary epithelial cells. The doubling time of tumor cells in vitro ranged from 2.6 to 3.6 days. The cultured cells were characterized as mammary carcinoma cells by their tumorigenicity in nude mice. Of 14 of the 23 short-term cell lines tested, 5 grew in nude mice and eventually regressed, 3 grew progressively in nude mice, and the remaining 6 did not grow within 3 months. To examine the feasibility of cytokine gene transfer into human mammary carcinoma cells, we introduced the cDNA for human tumor necrosis factor-alpha (TNF-alpha) into short-term cell lines with a retroviral vector. In our short-term primary breast cancer cell lines derived from breast tumors, TNF-alpha secretion ranged between 89 ng/10(6) cells/48 h and 479 ng/10(6) cells/24 h. These findings indicate that short-term primary human mammary carcinoma cell lines can be grown consistently from breast tumors, and that retroviral mediated-cytokine gene transfer into short-term human mammary carcinoma cells is feasible and may be of potential use in immunotherapy trials.

CD4+ T lymphocytes infiltrating human breast cancer recognise autologous tumor in an MHC-class-II restricted fashion.

Tumor-infiltrating lymphocytes (TIL) were derived from primary breast tumors, metastatic lymph nodes and malignant pleural effusions from 34 patients with breast cancer. TIL were cultured for approximately 30 days and studied for phenotype, cytotoxicity, and the ability to secrete cytokines in response to autologous tumor stimulation. Tumor specimens were obtained from two different sites in 7 patients, resulting in 41 samples from which 38 TIL cultures were established. In addition to screening 38 bulk TIL cultures, TIL from 21 patients were separated into CD4+ and CD8+ subsets and extensively studied. Three CD4+ TIL were found specifically to secrete granulocyte macrophage-colony-stimulating factor and tumor necrosis factor alpha when stimulated by autologous tumor and not by a large panel of stimulators (24-34) consisting of autologous normal cells, allogeneic breast or melanoma tumors and EBV-B cells. This cytokine release was found to be MHC-class-II-restricted, as it was inhibited by the anti-HLA-DR antibody L243. These 3 patients' EBV-B cells, when pulsed with tumor lysates, were unable to act as antigen-presenting cells and induce cytokine secretion by their respective CD4+ TIL. These findings demonstrate that MHC-class-II-restricted CD4+ T cells recognising tumor-associated antigens can be detected in some breast cancer patients.

Tumour necrosis factor-alpha modulates oestradiol responsiveness of MCF-7 breast cancer cells in vitro.

We studied the effect of tumour necrosis factor-alpha (TNF) on oestradiol regulation of growth and metabolism of MCF-7 breast cancer cells to determine whether TNF altered the oestradiol responsiveness of these cells. We found that TNF antagonized oestradiol stimulation of cell growth in a dose-dependent manner, with partial inhibition at 1.0 U/ml and complete inhibition at 1000 U/ml. TNF inhibited cell cycle progression, increasing cells in the G0G1 phase and blocking oestradiol-stimulated progression into the S phase. We examined the effect of TNF on three oestrogen-regulated proteins, the oestrogen receptor (ER), the progesterone receptor (PR) and insulin-like growth factor-I (IGF-I). TNF down-regulated the ER and up-regulated the PR. Both of these processes were enhanced by the addition of oestradiol. The effects of TNF on the ER and PR were dose-dependent and occurred without a change in the Kd of the receptor. TNF did not change the respective steady-state mRNA levels. In addition, TNF did not alter secretion of IGF-I either in the absence or presence of oestradiol, indicating that the effects of TNF on oestrogen-regulated proteins in selective. These findings indicate an important interaction between the immune and endocrine systems. The cytokine TNF has a prominent effect on oestradiol stimulation of MCF-7 cells, blocking its proliferative response and enhancing certain metabolic effects. These actions may be mediated in part through modulation of the ER, although other pathways appear to be involved.

Interleukin-1 alpha and interleukin-6 act additively to inhibit growth of MCF-7 breast cancer cells in vitro.

We studied the effects of interleukin-1 alpha (IL-1) and interleukin-6 (IL-6) on MCF-7 breast cancer cells to determine whether these cytokines act additively/synergistically to alter cell growth and metabolism. We found that IL-1 alone (1000 units/ml) inhibited cell growth to a greater degree (83.8%) than IL-6 alone (29.2%, P < 0.001). The combination of IL-1 + IL-6 caused greater inhibition of growth (92.9%, P < 0.02) than either cytokine alone. The additive effect was dose dependent for both IL-1 and IL-6. IL-1 and IL-6 also antagonized estradiol (10(-9) M) stimulated growth. Antagonism by the combination was greater than for either cytokine alone (P < 0.001). IL-1 or IL-6 alone each down-regulated the estrogen receptor (36.7%, P < 0.01, and 23.2%, P < 0.05, respectively), but the combination IL-1 + IL-6 did not cause a significantly greater effect than IL-1 alone. Neither IL-1 or IL-6 blocked estradiol stimulation of progesterone receptor (PR) synthesis; however, the combination IL-1 + IL-6 increased PR content by 28.4% (P < 0.01). IL-1, but not IL-6, increased secretion of transforming growth factor-beta (TGF-beta) by 2.45-fold over 72 h (P < 0.01). The increase was time dependent (detectable at 24 h) and dose dependent (maximum increase of 5.3-fold, 10,000 units/ml, P < 0.02). IL-1-induced TGF-beta secretion was blocked by estradiol (10(-9) M). Neither cytokine altered secretion of insulin-like growth factor-1. These findings indicate that IL-1 and IL-6 act additively to inhibit growth in the absence or presence of estradiol and modulate the estrogen receptor and progesterone receptor content of these cells. TGF-beta may mediate the effects of IL-1; however, other pathways appear to be required for the additive effects of these cytokines.

Interleukin-1 alpha and tumor necrosis factor-alpha (TNF alpha) inhibit growth and induce TNF messenger RNA in MCF-7 human breast cancer cells.

We studied the effects of interleukin-1 alpha (IL-1) and tumor necrosis factor-alpha (TNF), alone and in combination, on MCF-7 breast cancer cells to determine whether these cytokines alter cell growth, TNF gene expression, and TNF secretion. We found that IL-1 alone and TNF alone inhibited cell growth in a dose-dependent manner. Each cytokine arrested growth in the G0/G1 phase of the cell cycle, with maximum growth inhibition at 1000 U/ml (P less than 0.05) and 100 U/ml (P less than 0.01), respectively. However, the combination of these two cytokines did not result in greater growth inhibition or a greater percentage of cells arrested in the G0/G1 phase of the cell cycle compared with each cytokine alone. We examined the effect of exogenous IL-1 and TNF on TNF gene expression by Northern blot analysis. In the absence of any cytokine, these cells do not express TNF mRNA. Exposure to IL-1 (1000 U/ml) induced TNF mRNA at 3 h; however, mRNA levels diminished thereafter to barely detectable levels by 24 h. Exposure to TNF (1000 U/ml) also induced TNF mRNA at 3 h, but in contrast to IL-1, the level of enhanced expression persisted at these levels through 72 h of exposure. Secretion of TNF by these cells is induced by exogenous TNF, but not by IL-1. IL-1 and TNF in combination do not produce greater inhibition of growth, greater amounts of TNF mRNA at 3 h, or greater secretion of TNF than that produced by TNF alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin 1 alpha blocks estradiol-stimulated growth and down-regulates the estrogen receptor in MCF-7 breast cancer cells in vitro.

We studied the effect of interleukin 1 alpha (IL-1 alpha) on estradiol stimulation of cell growth and estrogen receptor (ER) content in MCF-7 human breast cancer cells in vitro to determine if IL-1 alpha altered cellular estradiol responsiveness. We found that IL-1 alpha blocked estradiol-stimulated growth of these cells in a dose-dependent manner (complete antagonism at 1000 units/ml: day 7 mean growth = vehicle, 47.7 micrograms DNA; estradiol 10(-10) M, 95.1; IL-1 alpha/estradiol, 44.6) and at all concentrations of estradiol from 10(-8) to 10(-11) M. IL-1 alpha in combination with trans-hydroxytamoxifen further inhibited estradiol-stimulated growth (vehicle = 44.8 micrograms DNA, estradiol = 108.3, estradiol/trans-hydroxytamoxifen = 47.8, IL-1 alpha/estradiol/trans-hydroxytamoxifen = 3.0, P less than 0.01). Inhibition with trans-hydroxytamoxifen was IL-1 alpha dose dependent (maximum = 97% at 1000 units/ml, P less than 0.01) and estradiol dose dependent (reversible with 10(-8) M estradiol, maximum inhibition at 10(-10) M estradiol). Concomitantly, IL-1 alpha down-regulated ER concentration by 38.0-43.7% (P less than 0.01) as measured by immunoreactivity or Scatchard analysis, respectively. This occurred as early as 3 h without a change in the Kd (vehicle = 0.23 nM, IL-1 alpha = 0.24 nM), persisted for at least 48 h, was dose dependent (maximum, 43.7% at 1000 units/ml, P less than 0.01), and was blocked by cycloheximide. IL-1 alpha, however, did not block estradiol stimulation of progesterone receptor content (vehicle = 221.9, IL-1 alpha = 238.9 fmol/mg protein) and did not block estradiol down-regulation of ER content. Furthermore, IL-1 alpha alone did not alter levels of ER mRNA and did not alter estradiol down-regulation of ER mRNA. These findings indicate that while IL-1 alpha antagonizes estradiol stimulation of growth and reduces ER content, its mechanism may involve other non-estrogen-regulated pathways.

Increased uptake of thymidine in the activation of sea urchin eggs. III. Effects of aphidicolin.

Uptake and phosphorylation of externally supplied [3H]-thymidine are fully stimulated in fertilized sea urchin eggs exposed to 5.0 micrograms/ml aphidicolin. As in untreated controls, the rate of uptake in aphidicolin-treated eggs increases greater than 50-fold shortly after fertilization, and greater than 85% of the transported thymidine is immediately phosphorylated to the triphosphate. The intracellular levels of [3H]-thymidine triphosphate (3H-dTTP) resulting from an external supply of [3H]-thymidine is therefore equal in aphidicolin-treated and untreated fertilized eggs. Under the same experimental conditions, the incorporation of externally supplied [3H]-thymidine into newly synthesized DNA of fertilized eggs is 90% inhibited by exposure to aphidicolin. The full availability of 3H-dTTP in these eggs further suggests that aphidicolin inhibits specifically at the level of DNA synthesis. This inhibitory effect is proportional to the concentration of aphidicolin between 0 and 5.0 micrograms/ml. In the continuous presence of 5.0 micrograms/ml aphidicolin, fertilized eggs fail to undergo mitotic chromosome condensation, nuclear envelope breakdown, and cytokinesis, suggesting a dependent link between these processes and the completion of nuclear DNA synthesis.