Telomerase activity and p53-dependent apoptosis in ovarian cancer cells

We conducted the present study to determine the relationship between p53-dependent apoptosis and telomerase activity in ovarian cancer cells. A human ovarian adenocarcinoma cell line, SK-OV-3 that had homozygous deletion of the p53 gene was used in this study. Wild-type p53 genes were transducted to SK-OV-3 cells with a recombinant adenovirus that contained a wild-type p53 gene (AxCAp53). IC(50)to cisplatin (CDDP) was 12.9 microM for SK-OV-3 cells and 9.2 microM for p53 gene-transducted SK-OV-3 cells. The apoptotic index for cells with p53 gene transduction was significantly higher than cells without transduction. Additionally, p53 gene transduction significantly enhanced CDDP-induced apoptosis. Bax protein in SK-OV-3 cells did not differ before and after exposure to CDDP. In SK-OV-3 cells with transduction of the p53 gene, the expression of p53 and Bax proteins increased after exposure to CDDP. Expression of Bcl-xL decreased after exposure to CDDP in SK-OV-3 cells with and without transduction. The telomerase activity in SK-OV-3 cells with the p53 gene was significantly lower compared with the cells without the p53 gene. CDDP exposure did not affect telomerase activity and human telomerase reverse transcriptase (hTERT) expression in both cell lines. We suggest that the p53 gene may relate to telomerase activity, but that p53-dependent apoptosis does not affect the activity.

Correlation between loss of PTEN expression and Akt phosphorylation in endometrial carcinoma

The tumor suppressor PTEN acts as a lipid phosphatase, regulates the phosphatidylinositol 3-kinase (PI3K)/Akt-signaling pathway, and modulates cell cycle progression and cell survival. Somatic mutations of PTEN have been reported in a variety of cancers, especially in endometrial carcinoma. To clarify whether and how PTEN and the PI3K/Akt pathway relates to endometrial carcinoma, we examined the expression of those pathway-related proteins in patients with endometrial carcinoma. Of 103 endometrial carcinomas, 37 (36%) showed negative immunohistochemical staining of PTEN. Western blotting revealed that the expression of PTEN in PTEN-negative cases was significantly lower compared with that in positive cases. In contrast, phospho-Akt level in negative cases was significantly higher. We found a significant inverse correlation between PTEN and phospho-Akt (r = -0.796). The expression of phospho-Bad was greater in negative cases, suggesting that Bad might be a target for AKT: The present study demonstrates the phosphorylation of Akt accompanied by the loss of PTEN in clinical specimens of endometrial carcinomas.

Cellular efflux pump and interaction between cisplatin and paclitaxel in ovarian cancer cells

OBJECTIVE

The aim of this study was to evaluate the combination effect of paclitaxel (PTX) and cisplatin (CDDP) and to determine the mechanisms of interaction between these agents.

METHODS AND RESULTS

We used human ovarian adenocarcinoma cell lines, namely a parent cell line (KF), a CDDP-resistant cell line (KFr) and a PTX-resistant cell line (KFTx).The combination effect of PTX and CDDP was synergistic on KF and KFTx and additive on KFr. The incidence of anaphase or telophase, evaluated by immunofluorescence microscopy, decreased with PTX and significantly decreased with PTX and CDDP in KF and KFTx. The concentration of PTX, which was measured by high-performance liquid chromatography, was higher in KF and KFTx cells treated with a combination of PTX and CDDP than those treated with PTX alone. Multidrug resistance gene mRNA appeared in KFTx and its expression decreased after exposure to PTX and CDDP. After exposure to CDDP, the expression of multidrug resistance-associated protein (MRP) and the concentration of glutathione increased in KF, but not in KFr or KFTx. MRP expression slightly increased in KF and KFTx after exposure to PTX. In contrast, its expression decreased in KFr.

CONCLUSION

The present study suggests that CDDP enhances PTX accumulation and that the interaction of these agents is synergistic in CDDP-sensitive cells.

Sensitivity to paclitaxel is not related to p53-dependent apoptosis in ovarian cancer cells

We conducted this study to determine whether the sensitivity of ovarian cancer cells to paclitaxel (PTX) relates to cells undergoing p53-dependent apoptosis. Human ovarian adenocarcinoma cell lines (SK-OV-3, KF and KP cells) were used in this study. In SK-OV-3 and KP cells, which have a homozygous deletion of the TP53 gene, wild-type TP53 gene-transduction markedly enhanced the sensitivity to cisplatin (CDDP), but did not enhance the sensitivity to PTX. In all cells, the apoptotic index was increased by CDDP or PTX. After exposure to CDDP, p53 and Bax protein expression increased and Bcl-xL expression decreased in the KF cells and TP53 gene-transducted SK-OV-3 cells. However, these proteins did not change in KP cells. Therefore, the role of p53 in CDDP-induced apoptosis depends upon the cell type. In contrast, TP53 gene status did not correlate with PTX-induced cytotoxicity in any of the cell lines with differing apoptotic pathways. In conclusion, the sensitivity to PTX may not be related to p53-dependent apoptosis in ovarian cancer cells.

Prognosis and clinicopathological characteristics of Ib-IIb adenocarcinoma of the uterine cervix in patients who have had radical hysterectomy

AIMS

The aim of the present study was to evaluate the outcome of patients with stage lb-IIb cervical adenocarcinoma treated with radical hysterectomy, and to determine the clinicopathological characteristics of those patients.

METHODS

A total of 255 patients with cervical carcinoma stage Ib-IIb (57 adenocarcinoma and 198 squamous cell carcinoma) who had undergone radical hysterectomy were included in this study. Patient survival distribution was calculated using the Kaplan-Meier method.

RESULTS

The estimated 5-year survival rate for patients with adenocarcinoma was significantly poorer than that for patients with squamous cell carcinoma (77.9% vs 91.7%). The survival rate in stage Ib patients did not differ between two groups (95.8% vs 94.4% respectively). The incidence of lymph node involvement was significantly higher in patients with adenocarcinoma than in those with squamous cell carcinoma (31.6% vs 14.8%). Among patients receiving post-operative radiotherapy, the survival rate for adenocarcinoma (71.1%) was significantly poorer than that for squamous cell carcinoma (90.0%). When patients underwent radical hysterectomy, the survival rate for stage II patients with adenocarcinoma was significantly poorer than that for patients with squamous cell carcinoma.

CONCLUSIONS

The higher incidence of lymph node involvement and lower response to post-operative radiotherapy are considered to be factors of poorer prognosis in cervical adenocarcinoma.

Alteration of telomerase activity in ovarian cancer after chemotherapy

To elucidate the relationship between telomerase activity and chemosensitivity in epithelial ovarian cancer, telomerase activity and telomere length (TRF) were examined before and after chemotherapy. Of 21 patients, 9 patients responded to chemotherapy and 12 did not. The positivity of telomerase activity did not significantly differ between responders and nonresponders. There were no differences in the mean length and the distribution of TRF between the two groups. Those distributions became narrow after chemotherapy in both groups. Seven nonresponders (58.3%) exhibited an increase in telomerase activity after chemotherapy but none of the responders showed an increase in activity. Telomerase activity may relate to chemosensitivity in epithelial ovarian cancer.