Although estrogen is known to activate endothelial nitric oxide synthase (eNOS) in the vascular endothelium, the molecular mechanism responsible for this effect remains to be elucidated. In studies of both human umbilical vein endothelial cells ( The inhibitory effect of estrogen on the development of atherosclerosis has been suggested by abundant human epidemiological and animal experimental data (1-9). The incidence of atherosclerotic diseases is lower in premenopausal women than in men, steeply rises in postmenopausal women, and is reduced to premenopausal levels in postmenopausal women who receive estrogen therapy (10 -12). Until recently, the atheroprotective effects of estrogen were attributed principally to the effects on serum lipid concentrations. However, estrogeninduced alterations in serum lipids account for only approximately one-third of the observed clinical benefits of estrogen (12)(13)(14). Recent evidence suggests that the direct actions of estrogen on blood vessels contribute to the cardioprotective effects of estrogen (13, 15). There are many kinds of direct effects of estrogen on blood vessels, such as estrogen-induced increases of vasodilatation and inhibition of the response of blood vessels to injury and the development of atherosclerosis. However, the molecular mechanism underlying the estrogeninduced vasodilatation has not yet been determined. Several studies suggest that a key mediator of this vasodilator response could be the endothelium-derived relaxing factor nitric oxide (NO), and that brief treatment with estrogen increases basal NO release in endothelial cells without elevation of eNOS mRNA or protein (16). Estrogen activates endothelial nitric oxide synthase (eNOS) without altering expression of the eNOS gene in vascular endothelium (17)(18)(19)(20). However, the details of the mechanism of the estrogen-induced eNOS activation are not yet well understood.The serine/threonine kinase termed Akt or protein kinase B (PKB) 1 is an important regulator of various cellular processes, including glucose metabolism and cell survival (21, 22). Activation of receptor tyrosine kinases and G-protein-coupled receptors, and stimulation of cells by mechanical force, can lead to the phosphorylation and activation of . Akt was identified as a downstream component of survival signaling through phosphatidylinositol 3-kinase (PI3K) (26 -30). Akt may be regulated by both phosphorylation and the direct binding of PI3K lipid products to the Akt pleckstrin homology domain. Akt can then phosphorylate substrates such as glycogen synthase kinase-3, 6-phosphofructo-2-kinase, and BAD. More recently, it was found that eNOS is also an Akt substrate and is activated by Akt-dependent phosphorylation to release NO in endothelial cells (31-34).The actions of estrogen can be mediated by the classical nuclear receptors, ER␣ and ER␤ (35,36) or through other putative membrane receptors. By definition, rapid effects of estrogen that involve nongenomic mechanisms are independent of transcriptional activation by the nuclea...

We have studied the roles of c-Jun N-terminal protein kinase (JNK) and extracellular signal-regulated protein kinase (ERK) cascade in both the cisplatin-resistant Caov-3 and the cisplatin-sensitive A2780 human ovarian cancer cell lines. Treatment of both cells with cisplatin but not transplatin isomer activates JNK and ERK. Activation of JNK by cisplatin occurred at 30 min, reached a plateau at 3 h, and declined thereafter, whereas activation of ERK by cisplatin showed a biphasic pattern, indicating the different time frame. Activation of JNK by cisplatin was maximal at 1000 M, whereas activation of ERK was maximal at 100 M and was less at higher concentrations, indicating the different dose dependence. Cisplatin-induced JNK activation was neither extracellular and intracellular Ca 2؉ -nor protein kinase C-dependent, whereas cisplatin-induced ERK activation was extracellular and intracellular Ca 2؉ -dependent and protein kinase C-dependent. A mitogen-activated protein kinase/extracellular signal-regulated kinase kinase inhibitor, PD98059, had no effect on the cisplatin-induced JNK activity, suggesting an absence of cross-talk between the ERK and JNK cascades. We further examined the effect of each cascade on the viability following cisplatin treatment. Either exogenous expression of dominant negative c-Jun or the treatment by PD98059 induced sensitivity to cisplatin in both cells. Our findings suggest that cisplatin-induced DNA damage differentially activates JNK and ERK cascades and that inhibition of either of these cascades sensitizes ovarian cancer cells to cisplatin.

Purpose: Mammalian target of rapamycin (mTOR) plays a central role in cell proliferation and is regarded as a promising target in cancer therapy, including for ovarian cancer. This study aimed to examine the role of mTOR as a therapeutic target in clear cell carcinoma of the ovary, which is regarded as an aggressive, chemoresistant histologic subtype. Experimental Design: Using tissue microarrays of 98 primary ovarian cancers (52 clear cell carcinomas and 46 serous adenocarcinomas), the expression of phospho-mTOR was assessed by immunohistochemistry. Then, the growth-inhibitory effect of mTOR inhibition by RAD001 (everolimus) was examined using two pairs of cisplatin-sensitive parental (RMG1 and KOC7C) and cisplatin-resistant human clear cell carcinoma cell lines (RMG1-CR and KOC7C-CR) both in vitro and in vivo.Results: Immunohistochemical analysis showed that mTOR was more frequently activated in clear cell carcinomas than in serous adenocarcinomas (86.6% versus 50%). Treatment with RAD001 markedly inhibited the growth of both RMG1 and KOC7C cells both in vitro and in vivo. Increased expression of phospho-mTOR was observed in cisplatin-resistant RMG1-CR and KOC7C-CR cells, compared with the respective parental cells. This increased expression of phospho-mTOR in cisplatin-resistant cells was associated with increased activation of AKT. RMG1-CR and KOC7C-CR cells showed greater sensitivity to RAD001 than did parental RMG1 and KOC7C cells, respectively, in vitro and in vivo. Conclusion: mTOR is frequently activated in clear cell carcinoma and can be a promising therapeutic target in the management of clear cell carcinoma. Moreover, mTOR inhibition by RAD001 may be efficacious as a second-line treatment of recurrent disease in patients previously treated with cisplatin. (Clin Cancer Res 2009;15(17):5404-13) Ovarian carcinoma is the fourth most common cause of cancer death among women in the United States, with >21,000 new cases each year and an estimated 15,520 deaths in 2008 (1). Cytoreductive surgery followed by platinum-based chemotherapy usually combined with paclitaxel is the standard initial treatment and has improved survival in patients with epithelial ovarian cancer (2). However, there still exists many clinical problems in the treatment of epithelial ovarian cancer. One of the most important problems that needs to be resolved is the management of clear cell carcinoma of the ovary, which was first recognized by the WHO as a distinct histologic subtype in 1973 (3). The precise incidence of clear cell carcinoma is unknown, but it is reported to be 3.7% to 12.1% of all histologic subtypes among epithelial ovarian cancer (4).There have been two major clinical problems in the clinical management of clear cell carcinoma. First is its poor sensitivity to first-line platinum-based chemotherapy and the association with a worse prognosis than the more common serous adenocarcinomas. In the setting of front-line chemotherapy, the response rate to conventional platinum-based chemotherapy, platinum agent alo...

We investigated whether inhibition of nuclear factor-B (NF B) increases the efficacy of paclitaxel in in vitro