Centrosomes and their associated microtubules direct events during mitosis and control the organization of animal cell structures and movement during interphase. The centrosome replicates during the cell cycle, directs the assembly of bipolar mitotic spindles, and plays an important role in maintaining the fidelity of cell division. Recently, tumor suppressors such as p53 and retinoblastoma protein pRB have been localized to the centrosome in a cell cycle-dependent manner. Immunofluorescence microscopy and analysis of isolated centrosomes now provide evidence that BRCA1 protein, a suppressor of tumorigenesis in breast and ovary, also is associated with centrosomes during mitosis. Our results indicate that BRCA1 localizes with the centrosome during mitosis and coimmunoprecipitates with γ-tubulin, a centrosomal component essential for nucleation of microtubules. Furthermore, γ-tubulin associates preferentially with a hypophosphorylated form of BRCA1.

Centrosome abnormalities have been found in various cancer types and are thought to be involved in early development of cancer and/or progression. The contribution of centrosome abnormalities to ovarian tumorigenesis has not been previously evaluated. We sought to determine whether centrosome dysfunction occurs in ovarian tumorigenesis, and whether it could be used as an indicator of early neoplastic changes in ovarian surface epithelium (OSE). Primary cultures of normal OSE and ovarian tumors, as well as paraffin‐embedded normal ovaries and ovarian tumors of different stages, were used for immunostaining with a γ‐tubulin antibody. Centrosomes were considered abnormal if there were more than 2 per cell, if their sizes were greater than 2‐fold of a normal centrosome, and/or if they were abnormal in shape. Centrosomes in normal tissue were uniform in size, whereas centrosomes in ovarian tumors tended to be abnormal in size, number and shape. On average, 4.7% of cells in 5 primary normal OSE cultures had more than 2 centrosomes, whereas 14.1% of primary cells from 5 ovarian tumors displayed centrosome abnormalities (p = 0.008). Centrosome abnormalities were present in 60.9% of stage I (n = 23), 83.3% of stage II (n = 30) and all stage III (n = 10) paraffin‐embedded ovarian tumor samples examined, but not in normal tissues. In addition, centrosome abnormalities occurred more frequently in ovarian tumors with higher grade and aggressive serous subtype. This is the first demonstration that centrosome abnormalities occur in ovarian tumors. Centrosome dysfunction may be an early event in ovarian carcinogenesis and involved in ovarian tumor progression.

Breast cancer is the most commonly diagnosed cancer and the second leading cause of cancer death in women. Hormone receptor-positive breast cancer is usually subjected to hormone therapy, while triple-negative breast cancer is more formidable and poses a therapeutic challenge. Glucose transporters are potential targets for the development of anticancer drugs. In search of anticancer agents whose effect could be enhanced by a GLUT1 inhibitor WZB117, we found that MK-2206, a potent allosteric Akt inhibitor, when combined with WZB117, showed a synergistic effect on growth inhibition and apoptosis induction in breast cancer cells, including ER(+) MCF-7 cells and triple-negative MDA-MB-231 cells. The combination index values at 50% growth inhibition were 0.45 and 0.21, respectively. Mechanism studies revealed that MK-2206 and WZB117 exert a synergistic cytotoxic effect in both MCF-7 and MDA-MB-231 breast cancer cells by inhibiting Akt phosphorylation and inducing DNA damage. The combination may also compromise DNA damage repair and ultimately lead to apoptosis. Our findings suggest that the combination of Akt inhibitors and GLUT1 inhibitors could be a novel strategy to combat breast cancer.

Background: Ovarian cancer (OvCa) most often derives from ovarian surface epithelial (OSE) cells. Several lines of evidence strongly suggest that increased exposure to progesterone (P4) protects women against developing OvCa. However, the underlying mechanisms of this protection are incompletely understood. Methods: To determine downstream gene targets of P4, we established short term in vitro cultures of non-neoplastic OSE cells from six subjects, exposed the cells to P4 (10^-6 M) for five days and performed transcriptional profiling with oligonucleotide microarrays containing over 22,000 transcripts. Results: We identified concordant but modest gene expression changes in cholesterol/lipid homeostasis genes in three of six samples (responders), whereas the other three samples (non-responders) showed no expressional response to P4. The most up-regulated gene was TMEM97 which encodes a transmembrane protein of unknown function (MAC30). Analyses of outlier transcripts, whose expression levels changed most significantly upon P4 exposure, uncovered coordinate up-regulation of 14 cholesterol biosynthesis enzymes, insulin-induced gene 1, low density lipoprotein receptor, ABCG1, endothelial lipase, stearoyl- CoA and fatty acid desaturases, long-chain fatty-acyl elongase, and down-regulation of steroidogenic acute regulatory protein and ABCC6. Highly correlated tissue-specific expression patterns of TMEM97 and the cholesterol biosynthesis genes were confirmed by analysis of the GNF Atlas 2 universal gene expression database. Real-time quantitative RT-PCR analyses revealed 2.4-fold suppression of the TMEM97 gene expression in short-term cultures of OvCa relative to the normal OSE cells. Conclusion: These findings suggest that a co-regulated transcript network of cholesterol/lipid homeostasis genes and TMEM97 are downstream targets of P4 in normal OSE cells and that TMEM97 plays a role in cholesterol and lipid metabolism. The P4-induced alterations in cholesterol and lipid metabolism in OSE cells might play a role in conferring protection against OvCa.