[Effects of activated PPARgamma on the expression of PTEN gene in pancreatic cancer cells].

AIM: To explore the relationship between the expression of PTEN gene and the expression of PPARgamma, and the human pancreatic cancer cells PANC-1 were cultured in vitro. METHODS: The effects of rosiglitazone and GW9662 on the expression of PTEN gene and PTEN protein in the human pancreatic cancer cells PANC-1 were detected by RT-PCR and immunohistochemistry respectively. In addition, the percentage of the expression of PTEN protein was analyzed by flow cytometry. RESULTS: The expression of PTEN gene and PTEN protein in human pancreatic cancer cells PANC-1 were all increased significantly after treated with rosiglitazone. While those were markedly reduced in GW9662 treated groups, and it has a dose-effect relationship between them. CONCLUSION: The expression of PTEN gene were paralleled with the expression of PPARgammain human pancreatic cancer cells PANC-1, which may be related to its inhibitory effects on pancreatic tumor cells.

[HER-2 expression in local advanced breast cancer and the efficacy of neoadjuvant chemotherapy regimens].

OBJECTIVE: To investigate the relationship between HER-2 expression and the efficacy of neoadjuvant chemotherapy in local advanced breast cancer. METHODS: Different neoadjuvant chemotherapy regimens, namely CMF, CEF, and NEF, were administered in 132 patients with local advanced breast cancer for 2 cycles, each lasting for 28 days. According to the criteria recommended by WHO, the efficacy and safety of the regimens were evaluated after two cycles of neoadjuvant chemotherapy. HER-2 expression was examined by immunohistochemistry using specific monoclonal antibodies before chemotherapy and after surgery. RESULTS: The overall response rate (RR) of CMF, CEF, and NEF regimens were 39.5% (17/43), 54.3% (25/46) and 72.1% (31/43), with incidence of leukopenia of 34.9% (15/43), 58.7% (27/46) and 60.5% (26/43), respectively. Other adverse effects including decreased hemoglobin (Hb) level, thrombocytopenia, gastrointestinal irritation and alopecia were similar between the 3 groups (P>0.05). No significant variation in HER-2 expression occurred after administration of the 3 regimens. The overall RR to CMF regimen in HER-2-negative breast cancer patients was significantly higher than that in HER-2-positive patients, but showed no significant difference with CEF and NEF regimens. CONCLUSION: HER-2 expression is not decreased after neoadjuvant chemotherapy in breast cancer patients, and HER-2-positive breast cancer can be resistant to CMF regimen, but not to CEF and NEF regimens.

[Chemopreventive effect of celecoxib against DMBA-induced breast cancer and its mechanism].

OBJECTIVE: To evaluate the chemopreventive effect of celecoxib, a specific cyclooxegenease-2 (COX-2) inhibitor, on chemically induced breast cancer of rats and its effect on COX-2 expression. METHODS: 7, 12-dimethylbenz anthracene (DMBA) was administered intragastrically in SD female rats to establish breast cancer models, which were divided subsequently into control group, tamoxifen group and celecoxib group to receive different treatments accordingly. The occurrence rate of breast cancer was observed and the effect of celecoxib on COX-2 and vascular endothelial growth factor (VEGF) expressions assayed by immunohistochemical SP method. RESULTS: The incidence of breast cancer in tamoxifen group (48.15%) and celecoxib group (50.00%) were both significantly lower than that in the control group (85.71%; P=0.003 and P=0.004, respectively). The positivity rate of COX-2 expression in celecoxib group (28.57%) was significantly lower than those of tamoxifen group (48.15%) and control group (83.33%; P=0.001 and P=0.035, respectively). The positivity rate of VEGF expression in celecoxib group (42.86%) was significantly lower than that of control group (79.17%, P=0.023), but comparable with that in tamoxifen group (46.15%, P=0.863). CONCLUSION: Celecoxib can significantly suppress DMBA-induced breast cancer in female rats possibly through down-regulation of COX-2 and VEGF expressions.

[Chemopreventive effect of tamoxifen combined with celecoxib on DMBA-induced breast cancer in rats].

BACKGROUND & OBJECTIVE: Breast cancer can be prevented partly by tamoxifen. Cyclooxygenase-2 (COX-2) is expressed in many kinds of tumors, and correlated to the occurrence and progress of tumors. This study was to evaluate the chemopreventive effect of tamoxifen combined with celecoxib, a COX-2 selective inhibitor, on 7,12-dimethylbenz anthracene (DMBA)-induced breast cancer in rats. METHODS: DMBA was irrigated into the stomach of SD female rats to build breast cancer model. The rats were divided into 4 groups: control group, tamoxifen group, celecoxib group, and combination group; each group contained 30 rats. Tumor occurrence, latency period, number and volume of breast cancer were observed. RESULTS: The tumor occurrence rates in tamoxifen group (48.15%, 13/27) and celecoxib group (50.00%, 14/28) were lower than that in control group (85.71%, 24/28), and higher than that in combination group (21.43%, 6/28). The latency periods of tamoxifen group [(97.54+/-1.85) days] and celecoxib group [(96.79+/-2.89) days] were longer than that of control group [(89.50+/-5.99) days], and shorter than that of combination group [(103.67+/-3.39) days]. The tumor numbers of tamoxifen group (1.77+/-0.73) and celecoxib group (1.71+/-0.61) were less than that of control group (3.50+/-1.62), and more than that of combination group (1.17+/-0.42). The tumor volumes of tamoxifen group [(1.78+/-0.71) cm(3)] and celecoxib group [(2.05+/-1.04) cm(3)] were smaller than that of control group [(6.42+/-3.96) cm(3)], and larger than that of combination group [(0.71+/-0.96) cm(3)]. All differences were significant (P<0.05, respectively). CONCLUSION: Celecoxib and tamoxifen could effectively prevent the occurrence of DMBA-induced breast cancer in rats; the combination of them has better chemopreventive effect.