Effect of diethylaminoethyl-dextran on colony formation of human tumor cells in semisolid suspension cultures.

The effect of diethylaminoethyl-dextran on colony formation of established and primary human ovarian and breast tumor cells in semisolid suspension cultures was investigated. At the concentration of 250 to 300 micrograms/ml used in the human tumor stem cell assay, diethylaminoethyl-dextran inhibited in vitro growth of 3 of 4 human breast tumor cell lines and of 10 of 19 primary tumors. It did not affect growth in 7 primary tumors and enhanced colony formation in 2 tumors. We suggest that diethylaminoethyl-dextran may interact in the human tumor stem cell assay with other sites additional to sulfuric acid residues of the agar and that these effects may cancel or outweigh its purported beneficial effects.

Use of growth-stimulatory hormones to improve the in vitro therapeutic index of doxorubicin for human breast tumors.

Tumor-specific growth factors that increase the proliferative rate of tumor cells should, in theory, enhance the efficacy of cytotoxic drugs that have cell-cycle-dependent activity. To test this hypothesis, we measured the cytotoxicity of doxorubicin for clonogenic breast tumor cells in the presence and the absence of hormones that stimulate their in vitro growth (17 beta-estradiol, epidermal growth factor, hydrocortisone, and insulin). These growth factors increased the sensitivity to doxorubicin of the clonogenic cell populations from 20 of 25 breast tumors. Their effect was greatest on tumors from hormone-responsive patients. In contrast, these hormones increased the clonogenicity and sensitivity to doxorubicin of bone marrow progenitor cells to a much lesser degree. Hence, under the effect of these growth factors, the in vitro therapeutic index of doxorubicin improved for most of the tumors tested, while tamoxifen citrate, a tumor growth-inhibitory hormone, had the opposite effect. We conclude that tumor tissue-specific growth-stimulatory hormones can improve the in vitro efficacy of cell cycle-active anticancer drugs.

Quantitation of 1-beta-D-arabinofuranosylcytosine 5'-triphosphate in the leukemic cells from bone marrow and peripheral blood of patients receiving 1-beta-D-arabinofuranosylcytosine therapy.

A method for the detection and quantitation of 1-beta-D-arabinofuranosylcytosine 5'-triphosphate (ara-CTP), the active metabolite cells and leukemic cells of the peripheral blood from patients receiving ara-C therapy is described. ara-CTP is separated from normal cellular nucleotides by high-pressure liquid chromatography and is quantitated by its absorbance of ultraviolet light at 280 nm with a lower limit of sensitivity of 25 pmol/2 x 10(7) cell equivalents. During separate courses of continuous infusion of different therapeutic doses of ara-C, ara-CTP accumulated in the leukemic bone marrow cells of a patient with acute myelogenous leukemia in proportion to the dose of ara-C. Continuous infusion of ara-C (90 mg/sq m/day) resulted in plateau levels of ara-CPT in peripheral blast cells after 24 hr (115 pmol/1 x 10(7) cell equivalents). A priming dose of ara-C(125 to 250 mg/sq m) followed by a 1-hr infusion of an equal dose of ara-C to patients with acute myelogenous leukemia facilitated the determination of ara-CTP retention in bone marrow and peripheral blood leukemic cells in vivo. This procedure should be useful for extended studies of the biochemical pharmacology of ara-CTP in vivo.

Normalization of in vitro sensitivity testing of human tumor clonogenic cells.

The use of normal bone marrow (granulocyte-macrophage colony-forming units) as a point of reference to normalize the in vitro activities of anticancer agents has been investigated. The cytotoxic effects of four substituted anthraquinone derivatives, and of vinblastine on myeloid progenitors of different donors were reproducible up to a cell kill of approximately 60%. Equitoxic in vitro concentrations for normal bone marrows did not correlate with in vivo pharmacokinetic concentrations of these drugs. Breast tumor progenitor cells of 46 specimens were more sensitive than were bone marrow progenitors to the anthraquinone derivatives in 26 to 39% of instances, ratios which are similar to the clinically observed response rates of patients with breast carcinoma to these agents. Tumors were either sensitive or resistant to all four drugs in 68% (10 tumors were more sensitive, and 21 tumors were less sensitive than normal bone marrow); but in 32% of instances there were differences in tumor sensitivity for the four drugs, and the assay could select one to three drugs for which the tumor sensitivity was greater than that of bone marrow. Correlations of in vitro sensitivity and of clinical response to single agent treatments were determined in 21 patients, and the concordance was 71%. The value of the assay in predicting clinical response ranked best for sensitivity determinations within the normalized dose ranges, when testing within three different dose ranges was compared in a group of six patients. The concordance was higher in the small (1 or 2 metastatic sites) than in the large (greater than or equal to 3 metastatic sites) tumors (85 versus 50%), indicating a confounding influence of tumor load on the ability of the assay to predict efficacy of treatment. A rule of thumb is proposed for altering the in vitro sensitivity test results for large tumors that improves the overall concordance to 90%.

Sequence and functional characterization of the terminal exon of the human insulin receptor gene.

We present 5.1 kb of the 3' noncoding region sequence of the human insulin receptor gene and identification of four functional polyadenylation domains responsible for 3'-end processing of the 5.4, 6.9, 8.0 and 9.4 kb human insulin receptor mRNA, respectively. The insulin receptor gene contains five putative polyadenylation sites (P1-P5), located 5160, 6502, 7488, 8945 and 8957 base pairs (bp) downstream from the translational initiation site. All putative polyadenylation sites are flanked by upstream AU rich and downstream GU rich regions which regulate mRNA stability and mRNA cleavage, respectively. Also, two RNA stem-loop structures have been identified. To determine its role on gene expression, a reporter gene was constructed containing various lengths of the insulin receptor 3' UTR and transiently transfected into COS 7 cells. A 539 bp fragment (4897-5436 bp downstream from the IR translational initiation site) inhibited CAT expression by 5-6 fold. Further downstream addition of 1169 bp of the insulin receptor 3' untranslated region enhanced gene expression by 2-fold. These studies provide evidence that the insulin receptor 3' untranslated region can modulate gene expression.

Chemotherapy and hormonal therapy in combination.

The advantage of adding hormones to chemotherapy for the treatment of patients with breast carcinoma is uncertain, and benefits and disadvantages have been reported. An analysis of published randomized clinical trials reveals that the growth function (differentiation-inducing function v mitogenic function) of the hormone used may determine the ultimate benefit of combined modality treatments.

The true predictive value of the human tumor stem cell assay: does a workable assay select for treatment responders?

In practice, the human tumor clonogenic assay is workable for less than half of the patient population to which it is applied, since the remainder of the specimens fail to produce sufficient numbers of colonies. Thereby a bias may be introduced which could result in a false predictive value positive of the test. It is therefore necessary to compare the responses to treatment of patients whose tumors could be assayed in vitro to those whose tumors failed to grow adequately, to assure that the prevalence of treatment responders has not changed within the group of patients for which the assay worked. From an analysis of the treatment response of 70 patients with stage III and IV ovarian carcinomas and 70 patients with stage IV breast cancer, no selection bias did occur and no preferential in vitro growth of tumor samples from patients with treatment response was found.

Tamoxifen-citrate counteracts the antitumor effects of cytotoxic drugs in vitro.

Hormones and cytotoxic drugs are often combined in the treatment of patients with breast carcinoma to broaden the antitumor spectrum of the therapy. We found that, in vitro, the most commonly used endocrine agent, tamoxifen citrate, attenuates the cytotoxic potential of 5-fluorouracil (5-FU) and of doxorubicin. The effect was observed on estrogen receptor positive and on estrogen receptor negative breast tumor cells. Combinations of growth inhibitory hormones and cytotoxic drugs may therefore be counter-productive. For the treatment of hormone-independent tumors they may even be harmful since in these tumors tamoxifen exerts no independent cell kill that compensates for its modifying effect on the cytotoxicity of drugs.

Adjuvant therapy with escalating doses of doxorubicin and cyclophosphamide with or without leukocyte alpha-interferon for stage II or III breast cancer.

PURPOSE: A prospective study in breast cancer patients was undertaken to determine whether escalating doses of doxorubicin and cyclophosphamide would result in a higher fraction of patients free of disease, and to evaluate the role of leukocyte alpha-interferon. PATIENTS AND METHODS: Between 1982 and 1986, 319 consecutive patients with stage II or III breast cancer with one or more positive nodes were assigned randomly to receive adjuvant chemotherapy that consisted of escalating doses of doxorubicin and cyclophosphamide in combination with vincristine and prednisone or the same chemotherapy regimen followed by 1 year of leukocyte alpha-interferon. Doxorubicin was administered by 72-hour continuous infusion through a central venous catheter (maximum total cumulative dose, 430 mg/m2). All patients with positive or unknown estrogen receptor status were also given tamoxifen for 1 year. RESULTS: The median follow-up was 71 months (range, 35 to 99 months). Correlation of disease-free survival (DFS) with dose-intensity of cyclophosphamide and doxorubicin showed no improvement in DFS for patients who were able to receive escalated drug doses compared with those who were not. Doxorubicin administered by continuous infusion was associated with a negligible risk of cardiotoxicity in this study despite the administration of higher accumulative doses than in our previous adjuvant therapy studies. The DFS rates of patients who did and those who did not receive leukocyte alpha-interferon were similar. CONCLUSIONS: In this study, there was no real evidence that higher drug dose intensity was associated with longer DFS. Leukocyte alpha-interferon as it was used in this study had no therapeutic value. Doxorubicin administered by infusion was associated with a reduced risk of cardiotoxicity.

Nuclear protein-binding analysis of a GC-rich insulin-receptor promoter regulatory region.

We previously demonstrated that activation of the insulin-receptor promoter occurs between Xho I and HindIII restriction enzyme sites located 877 and 578 bp upstream, respectively, from the translational initiation site. Deletion mutants 5' of this promoter region were constructed with the reporter gene, CAT, and transiently transfected into HepG2 and MCF-7 cells. This study demonstrated that most of the promoter activity could be localized to a 40-bp region between -618 and -578. When attached to a heterologous SV40 early promoter, this 40-bp insulin-receptor regulatory region, in either orientation, stimulated the SV40 early promoter by approximately two- to threefold after transfection into HepG2 cells. EMSA demonstrated that the purified transcription factor, Sp1, binds to this transcription activator. DNA binding of protein obtained from crude HepG2 nuclear extracts demonstrated electrophoretically retarded bands that competed for the consensus Sp1 element; these bands were not observed in a similar analysis with crude MCF-7 nuclear extracts. However, in both HepG2 and MCF-7 cells, a protein was identified that specifically binds to this important insulin-receptor promoter region, but does not bind to the Sp1 consensus element. We conclude that activation of insulin-receptor gene transcription occurs in a 40 bp region 578 bp upstream from the translational initiation site, and that Sp1 and another nuclear factor other than Sp1 may be important in regulating transcription in HepG2 cells.

The results of modified use of chemotherapy for patients with metastatic breast cancer.

We investigated whether modifying standard chemotherapy with 5-fluorouracil, doxorubicin and cyclophosphamide (FAC) could improve the outcome of patients with advanced breast carcinoma. We changed the conventional FAC treatment as follows: firstly, we administered oestrogens during the delivery of chemotherapy. Secondly, we administered 5-fluorouracil by continuous infusion. Thirdly, we limited chemotherapy treatment to 12 cycles and did not continue treatment during remissions. We evaluated this modified treatment in 63 patients and compared its results to other treatments results given at this institution. We found that the modified treatment improved the quality of life and survival of premenopausal breast cancer patients.

Survival of human bone marrow cells after in vitro treatment with 12 anticancer drugs and implications for tumor drug sensitivity assays.

We investigated the responsiveness of human normal granulocyte-macrophage colony-forming units in culture (GM-CFUC) continuously exposed in vitro to 1 of 12 anticancer drugs. All drugs except bleomycin showed a simple negative exponential dose-survival curve. The in vitro toxicity of drugs in GM-CFUC did not always correlate with the relative myelosuppressive potency observed in vivo. In addition, tumor specimens from 38 patients mainly with ovarian cancer were cultured in a human tumor colony-forming assay and continuously exposed to drugs at low, intermediate, and high concentrations capable of killing 40%, 78%, and 99% of GM-CFUC, respectively. The most active drugs were cis-platinum, velban, 5-fluorouracil, and 5-fluoro-ara-AMP. Dose-survival curves of bone marrow progenitor cells may serve as an in vitro reference system for selecting appropriate drug concentrations of myelosuppressive drugs in drug-sensitivity assays of human tumors.

Role of culture conditions and exposure duration in determining sensitivity of human bone marrow progenitor cells to methotrexate.

The effect of drug concentration, exposure duration, and culture conditions on the cytotoxic activity of methotrexate (MTX) on normal granulocyte-macrophage colony-forming units in culture (GM-CFUC) was studied using a bilayer soft agar system with nucleoside-free medium. The degree of inhibition of colony formation depended on the type of serum supplementation. A 1 h or 2 h pulse treatment with 2 X 10(-4) M (100 micrograms/ml) MTX failed to kill GM-CFUC, when the cells were subsequently plated in a system containing 15% undialyzed fetal bovine serum (FBS). For continuous exposure the observed LD50 of MTX in the agar system was higher than 10(-4) M for 15% undialyzed FBS, 10(-5) M for 15% dialyzed FBS plus 0.25% undialyzed FBS, 10(-6) M for 15% dialyzed FBS, and 10(-8) M for 15% undialyzed horse serum. The difference for dialyzed FBS versus horse serum can be explained by differences in nucleoside concentrations. The difference for dialyzed FBS versus horse serum may be secondary to an enhancer of MTX in horse serum. For studying MTX sensitivity of human tumor cells in vitro, we suggest testing conditions that lie within the dose survival curve of GM-CFUC.

Inflammatory carcinoma of the breast: results of a combined-modality approach--M.D. Anderson Cancer Center experience.

A total of 106 patients with inflammatory carcinoma of the breast underwent combined-modality treatment consisting of doxorubicin-containing chemotherapy. All patients received three cycles of 5-fluorouracil, doxorubicin, and cyclophosphamide (FAC) before local therapy. From 1974 to 1977 (group A), primary radiotherapy was the local treatment modality and chemotherapy was given for a total of 24 months. From 1978 to 1981 (group B), mastectomy became the primary local treatment modality and FAC was reinstituted within 10-14 days after surgery; after completion of FAC, consolidation radiotherapy was given. From 1982 to 1986 (group C), vincristine and prednisone were added to FAC, and doxorubicin was given by continuous infusion. The median follow-up of the three groups was 56 months. For patients alive at the time of analysis, median follow-ups were 141, 111, and 49 months in groups A, B, and C, respectively. Disease-free survival at 5 years was 35%, 22%, and 41% for groups A, B, and C, respectively, and respective overall survival at 5 years was 37%, 30%, and 48%. Mastectomy in addition to radiotherapy resulted in local control rates similar to those obtained with radiotherapy alone, but this approach would result in fewer late sequelae of high-dose irradiation and provided histologic staging for chemotherapy response. The patients treated on protocol C had slightly better disease-free and overall survival, but the differences were not statistically significant. The 5-year disease-free survival of patients achieving a clinical complete remission (CR) or partial remission (PR) was superior to that of patients whose response was less than a PR. There was no episode of doxorubicin-related cardiac toxicity in group C. Combined-modality treatment for inflammatory carcinoma of the breast resulted in improved survival.

Cisplatin in combination with continuous infusion vinblastine for refractory breast cancer.

We assessed antitumor activity and toxic effects of cisplatin and 5-day continuous infusion vinblastine in 25 evaluable patients with metastatic breast carcinoma refractory to one or more chemotherapeutic regimens. We administered cisplatin at 70 mg/m2 i.v. followed by vinblastine 1.5 mg/m2 daily for five consecutive days. In our heavily pretreated, poor performance patient population, we observed one complete response and four partial responses, with a median time to progression of 35 weeks. Toxic effects were significant and prevented dosage escalation. The addition of cisplatin does not appear to improve the therapeutic value of vinblastine alone.

Predictors of hormone response for patients with ER-unknown breast tumours.

Characteristics of cells that are associated with the hormonal dependence of tumours are described, and it is shown that clonogenicity and hormone-induced proliferative response of breast tumours are as good markers of hormonal dependence as is oestrogen receptor. Thus tumours that formed less than 150 colonies per 500,000 cells seeded and that increased their proliferative activity 1.8-fold or more in response to hormones were the tumours that were likely to respond to endocrine treatments, whereas all other tumours were likely to be refractory to endocrine treatments. These two criteria (clonogenicity and proliferative response to growth hormones) correctly identified the response to subsequent endocrine treatments in 15 out of 17 patients with oestrogen receptor-unknown tumours. It is proposed that they may constitute a substitute for the oestrogen receptor status in patients with non-biopsiable tumours, and an additional discriminant where the oestrogen receptor assay is available.

Regulation of insulin receptor gene expression. Cell cycle-mediated effects on insulin receptor mRNA stability.

Posttranscriptional mechanisms play important roles in insulin receptor gene regulation; variability in cellular insulin receptor number and the growth arrest-mediated increases in insulin receptor mRNA are secondary to changes in insulin receptor mRNA stability. Therefore, further characterization of the pathways and kinetics of insulin receptor mRNA degradation were investigated. The insulin receptor mRNA in the insulin receptor-rich Hep G2 cells is more stable compared with the insulin receptor-sparse MCF-7 cells. Growth arrest results in a significant rise in insulin receptor mRNA in both cell lines. The increase in mRNA is caused by changes in mRNA stability. The half-life of the insulin receptor mRNA in growth-arrested cells is approximately three times that of proliferating cells. The insulin receptor gene contains four polyadenylation sites that produce four species of mRNA of 5.4, 6.9, 8.0, and 9.4 kilobases (kb). The mRNA species are not coordinately regulated. The ratio of the most abundant species (9.4/6.9) is significantly larger in growth-arrested cells compared with proliferating cells. By utilizing a specific cDNA probe for the 9.4-kb mRNA species, it was determined that the diminished 9.4/6.9 ratio in proliferating cells was caused by a more rapid rate of the 9.4-kb mRNA degradation. The kinetics of insulin receptor mRNA degradation were investigated. Insulin receptor mRNA levels were reduced to 56% of their base line within 6 h when growth-arrested cells were stimulated to proliferate; protein inhibition with cycloheximide completely inhibited the decline in insulin receptor mRNA.