Rajani Rai

Mortalin and PINK1/Parkin‐Mediated Mitophagy Represent Ovarian Cancer‐Selective Targets for Drug Development

Abstract Mortalin is an essential chaperone for the import of nuclear‐encoded proteins into mitochondria and is elevated in ovarian cancer in association with poor patient prognosis. The investigational new drug, SHetA2, interacts with mortalin releasing its client proteins. In this study, interactions of SHetA2 moieties and mortalin substrate binding domain (SBD) amino acids are demonstrated by surface plasmon resonance (SPR) and nuclear magnetic resonance (NMR) to occur at low micromolar SHetA2 concentrations that selectively kill cancer cells over noncancerous cells. In both ovarian cancer and noncancerous cells SHetA2 reduces: mitochondria import of mortalin, degradation of mortalin's mitochondrial localization sequence (MLS), mortalin/inositol 1,4,5‐trisphosphate receptors complexes and oxidative phosphorylation. In cancer cells only, SHetA2 reduces calcium levels, mitochondrial length and fusion proteins, while inducing autophagy and PTEN‐induced kinase 1 (PINK1)/PARKIN‐mediated mitophagy. Noncancerous cells exhibit increased mitochondrial branch length in response to SHetA2 and a low level of inducible autophagy that is resistant to SHetA2. Inhibition of autophagosome‐lysosome fusion reduces, or increases, SHetA2 cytotoxicity in ovarian cancer or noncancerous cells, respectively. SHetA2 inhibits mortalin and growth, and induces mitophagy in ovarian cancer xenografts and increases survival post‐surgical tumor removal. In conclusion, SHetA2 binds directly to mortalin's SBD and causes distinct responses in ovarian cancer and noncancerous cells.

Targeting HSP70‐E7 Interaction With SHetA2: A Novel Therapeutic Strategy for Cervical Cancer

ABSTRACT Cervical cancer is predominantly driven by persistent infections with high‐risk human papillomavirus and the continuous activity of its E6 and E7 oncoproteins. This study explored the role of heat shock proteins 70 kDa (HSP70s) in enhancing the function of these oncoproteins and examined the impact of SHetA2, an investigational new drug, on this interaction. We found that HSP70 specifically binds to E7, but not E6, protein and that SHetA2 disrupts this binding. This disruption led to a significant reduction in E6 and E7 mRNA and E7 protein levels, while effects on E6 protein levels were minimal. SHetA2 treatment also resulted in altered levels of cell cycle regulatory proteins, reduced cell cycle progression, and decreased metabolic viability in cervical cancer cell lines and xenograft models. These findings support the potential of SHetA2 to impair cervical cancer progression by targeting HSP70/E7 interactions, highlighting its promise as a therapeutic strategy for treating cervical cancer.