Role of the beta isoform of 14-3-3 proteins in cellular proliferation and oncogenic transformation

The 14-3-3 proteins are associated with proto-oncogene and oncogene products. Here, we generated NIH 3T3 cells overexpressing the beta isoform of the 14-3-3 proteins (14-3-3 beta) to examine the function of this isoform in cellular proliferation and oncogenic transformation. Overexpression of 14-3-3 beta in NIH 3T3 cells stimulated cell growth and supported anchorage-independent growth in soft agar medium and tumor formation in nude mice. To elucidate the molecular mechanisms of 14-3-3 beta-mediated NIH 3T3 transformation, we examined the activity of mitogen-activated protein kinase (MAPK) after serum stimulation. Overexpression of 14-3-3 beta augmented MAPK activity after serum stimulation, and MAPK activity correlated well with the amount of 14-3-3 beta expression. The colony-forming ability of NIH 3T3 cells overexpressing 14-3-3 beta in soft agar medium was efficiently abolished by exogenous expression of a dominant-negative mutant of MEK1 and 14-3-3 beta physically interacted with Raf-1 in these cells. These findings indicate that 14-3-3 beta has oncogenic potential, mainly through enhancement of Raf-1 activation and resultant augmentation of signaling in the MAPK cascade.     

An analysis of serum interleukin-6 levels to predict benefits of medroxyprogesterone acetate in advanced or recurrent breast cancer

Treatment of advanced or recurrent breast cancer with medroxyprogesterone acetate (MPA) shows high response rates and the accessory effects of appetite stimulation, improvement in performance status (PS) and bone marrow protection. In recent years, interleukin-6 (IL-6) has been reported to cause cachexia. In this study, to clarify the significance of IL-6 in advanced or recurrent breast cancer, the relationship between the IL-6 level and clinical findings or effect of MPA was investigated. Sixty-five patients with recurrent or advanced breast cancer participated in a prospective study. The age of patients ranged from 28 to 79 years with an average age of 51.3 years. IL-6 level was investigated in these patients dosed with 800 mg/day of MPA and in 17 postoperative nonrecurrent patients. Serum MPA level was measured by high-performance liquid chromatography and IL-6 level was measured prior to MPA administration, 4 weeks (in 59 cases) and 12 weeks (in 32 patients) after MPA administration by ELISA. Serum IL-6 level was significantly higher in recurrent cases, especially in those with visceral metastasis. Further, in patients for whom MPA therapy was effective, the IL-6 level prior to the treatment was clearly low. The IL-6 level was significantly increased after 4 weeks. However, response to MPA was significantly higher and PS was improved in those cases demonstrating less increased IL-6 levels after 4 weeks. In addition, the effect of MPA was significantly related to a higher serum concentration of MPA-positive ER, and longer disease-free interval, although there was no significant predictive factor for the clinical effect of MPA therapy in multivariate analysis. In conclusion, MPA therapy was effective in cases demonstrating a low IL-6 level and less increased IL-6 levels after 4 weeks. PS was improved in those cases in which the degree of IL-6 increase was suppressed by MPA, and many such cases showed low IL-6 levels prior to MPA therapy. Furthermore, PS was improved even in nonresponders to MPA. Therefore, it is suggested that MPA therapy might be useful in treating recurrent breast cancer, and its benefits might be mediated by IL-6.     

Clinical significance of MUC1 and MUC2 mucin and p53 protein expression in colorectal carcinoma

BACKGROUND: Up-regulation of MUC1, down-regulation of MUC2 and p53 overexpression are seen in colorectal carcinomas. However, there have been few reports about the associations between MUC1, MUC2 and p53 expression and metastatic potential. The aim of this study was to investigate MUC1, MUC2 and p53 expression in colorectal carcinoma with special reference to regional and distant metastasis. METHODS: Eighty-six colorectal carcinomas were collected from patients undergoing tumor resection. Sections were used for MUC1, MUC2 and p53 immunostaining. Cancers were regarded as MUC1 or MUC2 positive when the positive cells were beyond 30% of cancer cells. Cancers with diffuse or nested patterns were regarded as having p53 overexpression. RESULTS: Of 86 cancers, 37 (43%) were MUC1 positive, 28 (33%) were MUC2 positive and 59 (69%) showed p53 overexpression. A difference was observed only in the frequency of MUC1 positivity with respect to depth of tumor invasion. Neither depth of tumor invasion nor histological differentiation had a positive correlation with MUC1, MUC2 and p53 overexpression. The frequency of MUC1 positive cells in Dukes' C and D tumors was significantly higher than that in Dukes' A and B tumors. The frequency of MUC1 positivity in tumors with hepatic involvement was significantly higher than that in tumors without hepatic involvement (100 vs 39%; p < 0.01). There was no difference in the frequency of MUC2 or p53 positivity in Dukes' stage or hepatic metastasis. MUC1 immunoreactivity of the surface was identical with that of the whole tumor in 81% (70/86) of carcinomas, MUC 2 in 87% and p53 in 100%. CONCLUSIONS: The results suggest that up-regulation of MUC1 is involved in the progression from the non-metastatic to the metastatic stage and that p53 abnormality is not directly involved in it. The data also imply that immunostaining of preoperative biopsy samples is useful for evaluating the immunoreactivity of the whole tumor.     

Arterial infusion chemotherapy for liver metastases from colorectal cancer--therapeutic effects of different protocols

The therapeutic effects of different protocols for arterial infusion chemotherapy were compared in patients with multiple liver metastases from colorectal cancer. A total of 49 patients with colorectal multiple liver metastases treated in our hospital since 1988 were the subjects. In order to compare the therapeutic effects on the regression of cancer and the survival rate, the subjects were assigned into Groups A-D, which were treated using different protocols. Group A received ADR, EPI, CDDP or 5-FU alone at first. If this drug was not effective, it was replaced with another of those mentioned here, and so on. Group B received CDDP 50 mg on day 1, 5-FU 500 mg/day from day 2 to day 7 and 5-FU 500 mg/day for 2 weeks thereafter (FP treatment). Group C received CDDP 50 mg at the time of reservoir insertion and 5-FU 1,000 mg for 5 hours thereafter (WHF treatment). Group D received 5-FU 1,000 mg for 24 hours on day 1, day 3, and day 5 of every week with combination of CDDP 5-10 mg/day from day 1 to day 5 and none on day 6 and day 7 (intermittent F + low-dose P treatment) for 3 weeks. The response rate was 33% for Group A (n = 18), 46% for Group B (n = 13), 25% for Group C (n = 8) and 80% for Group D (n = 10), showing significant differences between Group D and other groups. The 1-year survival rate was 50% for Group A, 46% for Group B, 29% for Group C and 89% for Group D. Significant differences in survival rate were found between Group B and D, and Group C and D.     

Induction of indirect donor-specific hyporesponsiveness by transportal RT1-peptide pulse in rat skin transplantation

In the present study, we examined whether transportal pulse of class I major histocompatibility complex (MHC) allopeptides can induce indirect (non-chimeric) donor-specific hyporesponsiveness, using a high-responder rat skin transplantation model. Two donor-specific 8-amino acid peptides corresponding to residues 58-65 and 70-77 in the alpha(1) helical region of RT1.A(a) were synthesized. In order to test immunogenicity of these peptides, mixed lymphocyte reaction (MLR) was performed. Then, 100-microg portions of peptides were injected into recipient Lewis (LEW, RT1.A(l)) rats via the portal vein 14 days before skin transplantation. Skin allografts from August Copenhagen Irish (ACI, RT1(a)) or Wistar King A (WKA, RT1(k), third-party) donors were transplanted to LEW (RT1(l)) recipients. Transportal pulse of residues 58-65 and 70-77 prolonged graft survival significantly in ACI-to-LEW skin transplantation (17.6+/-0.40 and 18.0+/-0.45 days) compared with control (14.2+/-0.37 days). However, pulse of residues 106-113, a non-donor-specific control, did not prolong graft survival time (14.6+/-0.40 days) in the same combination. Regarding the third-party donor, residues 58-65 injected into LEW recipients had no effect on survival time of skin grafts (19.0+/-0.84 days) derived from WKA donors compared with the untreated WKA-to-LEW control (19.4+/-0.93 days). Transportal pulse of RT1.A(a) peptides induced donor-specific hyporesponsiveness even in a high-responder rat skin transplantation model. Our results suggest that graft enhancement by transportal exposure to donor cells may not be induced by a chimeric process but, instead, by an indirect mechanism not involving intervention of viable donor cells.