FS-93, an Hsp90 inhibitor, induces G2/M arrest and apoptosis via the degradation of client proteins in oncogene addicted and derived resistant cancer cells

Targeting cancer cell mitochondria as a therapeutic approach: recent updates

Mitochondria play a key role in ATP generation, redox homeostasis and regulation of apoptosis. Due to the essential role of mitochondria in metabolism and cell survival, targeting mitochondria in cancer cells is considered as an attractive therapeutic strategy. However, metabolic flexibility in cancer cells may enable the upregulation of compensatory pathways, such as glycolysis to support cancer cell survival when mitochondrial metabolism is inhibited. Thus, compounds capable of both targeting mitochondria and inhibiting glycolysis may be particularly useful to overcome such drug-resistant mechanism. This review provides an update on recent development in the field of targeting mitochondria and novel compounds that impact mitochondria, glycolysis or both. Key challenges in this research area and potential solutions are also discussed.

Heat shock proteins and cancer: How can nanomedicine be harnessed?

Heat shock protein (hsp90) is an interesting target for cancer therapy because it is involved in the folding and stabilization of numerous proteins, including many that contribute to the development of cancer. It is part of the chaperone machinery that includes other heat shock proteins (hsp70, hsp27, hsp40) and is mainly localized in the cytosol, although many analogues or isoforms can be found in mitochondrion, endoplasmic reticulum and the cell membrane. Many potential inhibitors of hsp90 have been tested for cancer therapy but their usefulness is limited by their poor solubility in water and their ability to reach the target cells and the correct intracellular compartment. Nanomedicine, the incorporation of active molecules into an appropriate delivery system, could provide a solution to these drawbacks. In this review, we explain the rationale for using nanomedicine for this sort of cancer therapy, considering the properties of the chaperone machinery and of the different hsp90 analogues. We present some results that have already been obtained and put forward some strategies for delivery of hsp90 analogues to specific organelles.

The Role of Heat Shock Protein 90B1 in Patients with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a heterogenetic disorder in women that is characterized by arrested follicular growth and anovulatory infertility. The altered protein expression levels in the ovarian tissues reflect the molecular defects in folliculogenesis. To identify aberrant protein expression in PCOS, we analyzed protein expression profiles in the ovarian tissues of patients with PCOS. We identified a total of 18 protein spots that were differentially expressed in PCOS compared with healthy ovarian samples. A total of 13 proteins were upregulated and 5 proteins were downregulated. The expression levels of heat shock protein 90B1 (HSP90B1) and calcium signaling activator calmodulin 1 (CALM1) were increased by at least two-fold. The expression levels of HSP90B1 and CALM1 were positively associated with ovarian cell survival and negatively associated with caspase-3 activation and apoptosis. Knock-down of HSP90B1 with siRNA attenuated ovarian cell survival and increased apoptosis. In contrast, ovarian cell survival was improved and cell apoptosis was decreased in cells over-expressing HSP90B1. These results demonstrated the pivotal role of HSP90B1 in the proliferation and survival of ovarian cells, suggesting a critical role for HSP90B1 in the pathogenesis of PCOS. We also observed a downregulation of anti-inflammatory activity-related annexin A6 (ANXA6) and tropomyosin 2 (TPM2) compared with the normal controls, which could affect cell division and folliculogenesis in PCOS. This is the first study to identify novel altered gene expression in the ovarian tissues of patients with PCOS. These findings may have significant implications for future diagnostic and treatment strategies for PCOS using molecular interventions.

Combination of heat shock protein 90 and focal adhesion kinase inhibitors synergistically inhibits the growth of non-small cell lung cancer cells

Discovery of effective drug combinations is a promising strategy to improve patient survival. This study explores the impact of heat shock protein 90 (Hsp90) inhibition in combination with focal adhesion kinase (FAK) inhibitor on the growth of non-small cell lung cancer cells (NSCLC cells). Our data show that 17-N-Allylamino-17-demethoxygeldanamycin (17-AAG), a well-studied Hsp90 inhibitor, synergized with FAK inhibitor, PF-573228, on the growth inhibition of NSCLC cells. This combination effect was confirmed using additional chemically distinct Hsp90 inhibitor, STA-9090, which is currently undergoing phase 3 clinical evaluation. Co-treatment of NSCLC cells with Hsp90 and FAK inhibitors significantly enhanced the inhibition on long-term colony formation compared to that with single agent. Inhibition of FAK exacerbated the G₂ cell cycle arrest and annexin-V apoptotic staining induced by 17-AAG. Further mechanistic studies revealed that the combination of Hsp90 and FAK inhibitors reduced the activity of canonical proliferative and survival Akt-mTOR signaling, and increased pro-apoptotic caspase activation. Interestingly, FAK inhibition alone induced feedback activation of pro-survival Erk signaling, which was abrogated by co-treatment with Hsp90 inhibitors. Both Hsp90 and FAK inhibitors are undergoing clinical evaluation. Our studies suggest the tandem of Hsp90 and FAK inhibitors may provide an effective treatment option for NSCLC patients.