title: Overexpression of Bax induces down-regulation of store-operated calcium entry in prostate cancer cells.
abstract: Store-operated Ca2+ channels control homeostasis between extracellular Ca2+ reservoir and intracellular Ca2+ storage and play important roles in apoptosis in a wide variety of cells, including prostate epithelia. Recent studies have shown that the acquired apoptosis-resistant nature of androgen-independent prostate cancer is associated with reduced function of store-operated Ca2+ entry (SOCE). This study investigates the functional interaction between Bax and SOCE in the apoptosis signaling cascade in prostate cancer. Our previous findings show that NRP-154, an androgen-independent prostate cancer cell line, could sustain overexpression of exogenous Bax without undergoing apoptosis. Here we show that sustained overexpression of Bax in NRP-154 cells leads to down-regulation of SOCE and reduced Ca2+ storage inside the endoplasmic reticulum. While reduced SOCE may represent an adaptive mechanism for cell survival, increased levels of Bax in the latent state enhances the sensitivity of NRP-154 cells to TGF-beta and thapsigargin-induced apoptosis. This enhanced apoptosis can be reduced by 2-aminoethoxydiphenyl borate (2-APB), an inhibitor of SOCE, or reversed under conditions where SOCE is only partially activated. Our results demonstrate a functional interaction between Bax and SOCE in apoptosis of prostate cancer, and support the concept that improving this interaction has therapeutic implications for prostate cancer.
authors.affiliation: Department of Physiology and Biophysics, University of Medicine & Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.forename: Lin
authors.initials: L
authors.lastname: Zheng
authors.forename: Peihui
authors.initials: P
authors.lastname: Lin
authors.forename: David
authors.initials: D
authors.lastname: Danielpour
authors.forename: Zui
authors.initials: Z
authors.lastname: Pan
authors.forename: Jianjie
authors.initials: J
authors.lastname: Ma
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D045744:Cell Line, Tumor; D015536:Down-Regulation; D005786:Gene Expression Regulation; D006706:Homeostasis; D006801:Humans; D008297:Male; D051379:Mice; D011471:Prostatic Neoplasms / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000502:physiology; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D051028:bcl-2-Associated X Protein; D002118:Calcium