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.

Dexamethasone mediated stabilization of insulin receptor mRNA.

To determine the mechanism of glucocorticoid mediated enhancement of insulin receptor (IR) gene expression, we cotransfected a glucocorticoid receptor expression vector and a plasmid containing a reporter gene driven by an MMTV or IR promoter into COS 7 cells. Dexamethasone (Dex) increased MMTV promoter activity by 100% but had no effect on IR promoter activity. In the glucocorticoid responsive breast cancer cell line, MCF-7, Dex increased IR mRNA by 60%, and increased the IR mRNA half-life from approximately 6hrs to > 24 hrs. No glucocorticoid responsive element could be located in the insulin receptor 3' untranslated region. Glucocorticoids stabilize IR mRNA.

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.

The clonogenic growth of advanced breast tumour lesions adds no value to that of established clinical prognosticators for survival.

We measured the clonogenic growth of 110 breast cancer samples obtained from 107 patients with advanced disease. We determined clonogenicity under conventional conditions and under conditions supplemented with growth factors and hormones that target breast tissue. After a median follow-up period of 6 years we analyzed our data to determine if and to what degree clonogenic growth of metastatic breast tumours was related to the survival of patients. We found that tumour clonogenicity and patient survival correlated weakly, particularly if compared to the strong correlations of patient survival with either performance status or tumour bulk. Furthermore, an association between tumour clonogenicity and patient survival was visible only for clonogenicity that was determined under hormone-supplemented conditions, and only for tumour lesions that formed 50 or more colonies per 500,000 cells cultured. Thus, we conclude that clonogenic growth of breast tumour samples incompletely reflects the tumour features that determine the course of advanced disease.

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.

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.

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.

Clinical course of patients with breast cancer with ten or more positive nodes who were treated with doxorubicin-containing adjuvant therapy.

Between 1974 and 1986, 283 patients with ten or more positive nodes were treated in four prospective trials using doxorubicin-containing adjuvant chemotherapy. At a median follow-up of 92 months, 182 patients had had a recurrence, and 158 died. An estimated 41% and 37% were disease-free at 5 and 7 years, respectively. Patients with ten positive nodes had a significantly better disease-free survival than those with more than ten such nodes (P = 0.04). The disease-free survival rate and overall survival rate were not influenced by the estrogen receptor status of the tumor, patient age, or disease stage. Long-term data on a large number of patients treated at this institute showed the natural history of this subgroup of patients. Approximately 30% of patient survived disease-free at 10 years after treatment with the systemic therapies used in these protocols. Newer approaches are needed to alter the prognosis of this subgroup of patients further.

Is chemotherapy effective in reducing the local failure rate in patients with operable breast cancer?

To evaluate the role of chemotherapy in local control of primary breast cancer, the incidence of local failure was evaluated in 768 patients treated with surgery and adjuvant, combination chemotherapy that contained fluorouracil, doxorubicin, and cyclophosphamide (FAC) at our institute between 1974 and 1982. Of these patients, 429 received postoperative irradiation (XRT) before adjuvant therapy. A group of 178 historical control patients had mastectomies and received irradiation after surgery without chemotherapy. The rates of locoregional recurrence alone in the three groups were as follows: FAC, 12%; FAC plus XRT, 5%; and XRT, 10%. The difference in recurrence rates between the FAC group and the FAC plus XRT subgroup was significant (P less than 0.01). Local failure rates were evaluated by stage and nodal status; patients with Stage III disease and those with four or more disease-positive nodes had a higher incidence of local failure than did patients with Stage II disease or those who had one to three positive nodes. Systemic chemotherapy and local therapies resulted in 50% local control at the time of locoregional recurrence in patients treated with FAC, whereas local control was achieved in 18% of patients with local recurrence in the XRT subgroups. Overall life-time local control of disease was similar whether irradiation was administered initially (in the period after operation) or at the time of local recurrence. Irradiation after mastectomy remains an integral part of a combined modality approach in selected groups of patients.

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.

Sequential cyclic combined hormonal therapy for metastatic breast cancer.

Thirty postmenopausal patients who had evaluable estrogen receptor-positive or unknown metastatic breast cancer were treated with cyclic sequential combined hormonal therapy consisting of 50 micrograms of ethinylestradiol orally daily for 7 days followed by 400 mg of medroxyprogesterone acetate orally daily for 21 days, followed in turn by 7 days of rest. Cyclic administration was continued until progressive disease was detected. Patients who had had one previous chemotherapy regimen were included, but 63% of patients were previously untreated. Six patients achieved complete remission and 11, a partial remission, for an overall response rate of 57%. Median remission duration was 22 months; median time to disease progression for all 30 patients was 8 months. Toxicity consisted of cyclic vaginal bleeding, hot flashes, weight gain, irritability, and fluid retention. This cyclic, sequential hormonal regimen was effective and well tolerated.

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.

Decreased cardiac toxicity of doxorubicin administered by continuous intravenous infusion in combination chemotherapy for metastatic breast carcinoma.

Two hundred and seventy-four consecutive patients with measurable metastatic breast cancer, without prior exposure to cytotoxic agents were treated with tamoxifen, 5-fluorouracil, doxorubicin, and cyclophosphamide (FAC). The initial 133 patients received doxorubicin by bolus IV administration and for the next group of 141 patients doxorubicin was administered via a central venous catheter over a 48-hour (79 patients) or 96-hour (62 patients) continuous infusion schedule. Patients treated with bolus doxorubicin had this agent discontinued usually when 450 mg/m2 were reached; for patients in the infusion group treatment was continued until evidence of progressive disease or clinical or subclinical cardiac dysfunction developed. The complete remission rate was 21% the partial remission rate, 59%. There were no differences in response rate, response duration, or survival duration between groups of patients treated with doxorubicin by bolus, 48-hour or 96-hour infusion FAC. The incidence of moderate and severe nausea and vomiting was lower in the group of patients treated with infusion FAC as compared to bolus FAC (P less than 0.001); however, the incidence of mucositis was higher in the infusion group than in the bolus group (P less than 0.001). Doxorubicin administered by continuous infusion schedules was less cardiotoxic than when administered by bolus, as shown by a greater than 75% decrease in the frequency of clinical congestive heart failure at cumulative dosages greater than or equal to 450 mg/m2 (P = 0.004). Doxorubicin administered as a 48-hour or 96-hour continuous IV infusion is safer, and better tolerated than doxorubicin administered by bolus.

Management of stage III primary breast cancer with primary chemotherapy, surgery, and radiation therapy.

One hundred seventy-four evaluable patients with noninflammatory Stage III (both operable and inoperable) breast cancer were treated with a combined modality strategy between 1974 and 1985. All patients received combination chemotherapy with 5-fluorouracil, Adriamycin (doxorubicin), and cyclophosphamide (FAC) as their initial form of therapy. After three cycles of chemotherapy, local treatment in the form of a total mastectomy with axillary dissection, or radiotherapy, or both, was completed. Subsequently, adjuvant chemotherapy was continued. There were 48 patients with Stage IIIA, and 126 patients with Stage IIIB disease. A complete remission was achieved in 16.7% of the patients, and 70.7% achieved a partial remission after the initial three cycles of FAC. The complete response rate was higher for patients with Stage IIIA, than for patients with Stage IIIB disease. All but six of the 174 patients treated were rendered disease-free after induction chemotherapy and local treatment. The median follow-up of this group of patients is 59 months. The 5-year disease-free survival rates were 84% for patients with Stage IIIA, and 33% for patients with Stage IIIB disease. The 5-year survival rate for, patients with Stage IIIA was 84%, and for patients with Stage IIIB 44%. At 10 years, 56% of patients with Stage IIIA and 26% of patients with Stage IIIB disease are projected to be alive. Younger patients, and those with estrogen receptor-positive tumors, had a trend for better survival than older patients and those with estrogen receptor-negative tumors. The quality of response to induction chemotherapy correlated prominently with prognosis, as did compliance with treatment. Twenty-six patients (15.3%) had locoregional recurrence. This multidisciplinary approach to locally advanced breast cancer rendered most patients disease-free and produced an excellent local control rate. Modifications of this treatment strategy may result in further improvement of survival rates.

Adjuvant therapy of breast cancer with or without additional treatment with alternate drugs.

Three hundred ten patients with Stage II or Stage III breast cancer were entered on an adjuvant protocol consisting of a combination of 5-fluorouracil, doxorubicin, cyclophosphamide, vincristine, and prednisone (FACVP). In the second phase of the study, patients with estrogen receptor-negative tumors received sequential courses of methotrexate and vinblastine. Other patients, who were estrogen receptor-positive or unknown, were randomized to receive either tamoxifen alone or tamoxifen plus methotrexate and vinblastine. All therapy was completed within 1 year. The estimated disease-free rate at 5 years was 68% among patients with Stage II disease and 52% for patients who had Stage III disease. Among patients with estrogen receptor-positive tumors, disease-free survival was significantly prolonged in patients who received methotrexate and vinblastine in addition to tamoxifen (P = 0.04). However, this difference was less pronounced when all randomized patients (including those whose estrogen receptor status was unknown) were included in the comparison. Although most patients experienced moderate to severe granulocytopenia, infectious complications were infrequent. One patient died of septicemia. Congestive heart failure developed in two patients, one of whom had a history of myocardial infarction and congestive heart failure.

Sequential multiagent chemotherapy incorporating cisplatin, doxorubicin, and cyclophosphamide in the treatment of metastatic breast cancer.

Forty-three consecutive patients with metastatic breast cancer and clearly measurable disease were treated with sequential multiagent chemotherapy. Therapy consisted of the administration in fixed sequence of cisplatin, doxorubicin, and cyclophosphamide (PAC) (four cycles), vinblastine, doxorubicin, and dexamethasone (VAD) (six cycles), and VP-16, methotrexate, and 5-fluorouracil (VMF) (six cycles). At the conclusion of 16 cycles of chemotherapy, all treatment was stopped. Patients were assessed for toxicity and disease response after each treatment. Duration of response and survival rate were determined for 41 evaluable patients. The overall response rate was 80% with 24% complete responses, 15% to PAC alone. Median duration of response (8 months) and median survival (17 months) were not superior to other reported multiagent chemotherapeutic programs. Toxicity included neutropenic fever, sepsis, renal failure, and electrolyte imbalance. Administration of sequential multiagent chemotherapy with a cisplatin-containing combination did not improve response rate, complete responses (CR), duration of response, or survival in this group of previously untreated breast cancer patients.