Impact of SOCE Abolition by ORAI1 Knockout on the Proliferation, Adhesion, and Migration of HEK-293 Cells

Reduced store operated calcium entry contributes to autophagy mediated escape of prostate cancer to oxaliplatin treatment

Oxaliplatin, a third-generation platinum-based chemotherapeutic drug, induces cell cycle arrest and apoptosis in prostate cancer treatment. However, both intrinsic and acquired resistance mechanisms limit its therapeutic efficacy. Notably, chemotherapeutic agents often induce autophagy-a cellular recycling process-that can contribute to drug resistance. Calcium (Ca2+) signalling plays a pivotal role in regulating cell fate. However, the involvement of Ca2+ and Ca2+ channels in oxaliplatin resistance within prostate cancer cells remains controversial and poorly understood. In this study, we demonstrate that oxaliplatin treatment enhances autophagy in prostate cancer cells. Concurrently, oxaliplatin modulates the expression of key proteins involved in store-operated calcium entry (SOCE): it upregulates Orai3 channels while downregulating Orai1 and Stim1. These alterations result in diminished SOCE activity, contributing to an apoptosis-resistant phenotype. Importantly, we found that targeting Orai3 expression and inhibiting autophagy sensitizes prostate cancer cells to oxaliplatin-induced apoptosis. Our findings suggest that combining Orai3 downregulation with autophagy inhibition may enhance the efficacy of oxaliplatin in treating prostate cancer. This combinatorial approach could hold potential for overcoming resistance and improving therapeutic outcomes.

Cellular and Molecular Effects of the Bruck Syndrome-Associated Mutation in the PLOD2 Gene

Bruck syndrome is a rare autosomal recessive disorder characterized by increased bone fragility and joint contractures similar to those in arthrogryposis and is known to be associated with mutations in the FKBP10 (FKBP prolyl isomerase 10) and PLOD2 (Procollagen-Lysine,2-Oxoglutarate 5-Dioxygenase 2) genes. These genes encode endoplasmic reticulum proteins that play an important role in the biosynthesis of type I collagen, which in turn affects the structure and strength of connective tissues and bones in the body. Mutations are associated with disturbances in both the primary collagen chain and its post-translational formation, but the mechanism by which mutations lead to Bruck syndrome phenotypes has not been determined, not only because of the small number of patients who come to the attention of researchers but also because of the lack of disease models. In our work, we investigated the cellular effects of two forms of the wild-type PLOD2 gene, as well as the PLOD2 gene with homozygous mutation c.1885A>G (p.Thr629Ala). The synthesized genetic constructs were transfected into HEK293 cell line and human skin fibroblasts (DF2 line). The localization of PLOD2 protein in cells and the effects caused by the expression of different isoforms-long, short, and long with mutation-were analyzed. In addition, the results of the transcriptome analysis of a patient with Bruck syndrome, in whom this mutation was detected, are presented.

Side-by-side comparison of published small molecule inhibitors against thapsigargin-induced store-operated Ca2+ entry in HEK293 cells

Calcium (Ca2+) is a key second messenger in eukaryotes, with store-operated Ca2+ entry (SOCE) being the main source of Ca2+ influx into non-excitable cells. ORAI1 is a highly Ca2+-selective plasma membrane channel that encodes SOCE. It is ubiquitously expressed in mammals and has been implicated in numerous diseases, including cardiovascular disease and cancer. A number of small molecules have been identified as inhibitors of SOCE with a variety of potential therapeutic uses proposed and validated in vitro and in vivo. These encompass both nonselective Ca2+ channel inhibitors and targeted selective inhibitors of SOCE. Inhibition of SOCE can be quantified both directly and indirectly with a variety of assay setups, making an accurate comparison of the activity of different SOCE inhibitors challenging. We have used a fluorescence based Ca2+ addback assay in native HEK293 cells to generate dose-response data for many published SOCE inhibitors. We were able to directly compare potency. Most compounds were validated with only minor and expected variations in potency, but some were not. This could be due to differences in assay setup relating to the mechanism of action of the inhibitors and highlights the value of a singular approach to compare these compounds, as well as the general need for biorthogonal validation of novel bioactive compounds. The compounds observed to be the most potent against SOCE in our study were: 7-azaindole 14d (12), JPIII (17), Synta-66 (6), Pyr 3 (5), GSK5503A (8), CM4620 (14) and RO2959 (7). These represent the most promising candidates for future development of SOCE inhibitors for therapeutic use.