APOPTOSIS & CELL CYCLE IN BREAST & OVARIAN CANCER CELLS

本实验室的前期工作已经证明紫杉醇诱导的包括MCF-7乳腺癌细胞和BR卵巢癌细胞在内的多种细胞系的凋亡的初始阶段是通过Ras/Rac/Ask 1/JNKK/JNK信号转导通路介导的。 然而，紫杉醇作用的第二阶段不能通过阻断该途径来阻止。 最近对MCF-7细胞和多种其他细胞类型的研究表明，雌激素可以抑制凋亡，更具体地说，数据表明紫杉醇和雌激素之间可能存在相互作用，调节乳腺癌细胞的凋亡。 一些研究还表明，抗雌激素在ER阳性乳腺Ca细胞中具有凋亡作用。 我们已经积累了初步证据，证实雌激素在MCF-7细胞中的抗凋亡作用。 然而，雌激素作为抗凋亡剂的作用机制或其与促凋亡剂如紫杉醇的潜在相互作用是完全未知的。阐明这些相互作用是特别重要的，因为雌激素和微管干扰剂（MIA），如紫杉醇在临床上建立的作用，促进和治疗乳腺癌和卵巢癌分别。 我们认为雌激素可以作为抗凋亡剂，因为它们能够调节乳腺癌和卵巢癌细胞中Ras/Rac-JNK通路和Cdk/cyclin/Cdk抑制剂活性。 我们提出了以下具体目标来检验这一广泛的假设。 具体目标1：确定Cdks在MCF-7、BR和BG 1（卵巢）癌细胞中紫杉醇凋亡作用中的作用，目的是阐明细胞周期在紫杉醇作用中的作用（如果有的话）。 具体目的2：分析紫杉醇和雌二醇在上述细胞系中调节凋亡的假定相互作用。将设计实验以阐明雌激素与紫杉醇激活的Ras/Rac/JNKK/JNK/AP 1通路的相互作用。 具体目标3：鉴于雌激素可以调节几个基因的活性，这些基因可以调节细胞凋亡，我们将确定c-myc，Bc 12，p53，p300/CBP Akt在雌二醇的抗细胞凋亡作用中的潜在作用，使用野生型和显性阴性（DN）版本的相关基因的过表达。

Previous work in our laboratory has demonstrated that the paclitaxel induced initial phase of apoptosis in a variety of cell lines including MCF-7 breast cancer cells and BR ovarian cells is mediated through a Ras/Rac/Ask1/JNKK/JNK signal transduction pathway. However, the second phase of paclitaxel action is not prevented by blockade of this pathway. Recent studies on MCF-7 cells and a variety of other cell types suggests that estrogens can inhibit apoptosis, more specifically, data indicates a possible interaction between paclitaxel and estrogens in regulating apoptosis in breast cancer cells. Several studies also suggest that antiestrogens have apoptotic effects in ER positive breast Ca cells. We have accumulated preliminary evidence confirming an anti-apoptotic role for estrogens in MCF-7 cells. However, the mechanisms of estrogen action as an anti-apoptotic agent or their potential interactions with pro-apoptotic agents such as paclitaxel are totally unknown. Elucidations of these interactions is particularly significant since estrogens and microtubule interfering agents (MIAs) such as paclitaxel have clinically established roles in promotion and therapy of breast and ovarian cancer respectively. We propose that estrogens can act as anti-apoptotic agents because of their ability to regulate the Ras/Rac-JNK pathway and the Cdk/cyclin/Cdk inhibitor activity in breast and ovarian cancer cells. We have proposed the following Specific Aims to test this broad hypothesis. Specific Aim 1: Determine the role of Cdks in the apoptotic action of paclitaxel in MCF-7 and BR and BG1 (ovarian) cancer cells with the intention of elucidating the role of the cell cycle, if any, in paclitaxel action. Specific Aim 2: Analyze the putative interactions between paclitaxel and estradiol in regulating apoptosis in the above cell lines. Experiments will be designed to elucidate interaction of estrogens with the Ras/Rac/JNKK/JNK/AP1 pathway activated by paclitaxel. Specific Aim 3: Given the fact that estrogens can regulate the activity of several genes which can modulate apoptosis, we will determine potential role of c-myc, Bc12, p53, p300/CBP Akt in the anti apoptotic effects of estradiol using overexpression of wild type and dominant negative (DN) versions of the genes of interest.