TRPV5 and TRPV6 constitute the Ca2+ influx pathway in a variety of epithelial cells. Here, we identified S100A10 as the first auxiliary protein of these epithelial Ca2+ channels using yeast two‐hybrid and GST pull‐down assays. This S100 protein forms a heterotetrameric complex with annexin 2 and associates specifically with the conserved sequence VATTV located in the C‐terminal tail of TRPV5 and TRPV6. Of these five amino acids, the first threonine plays a crucial role since the corresponding mutants (TRPV5 T599A and TRPV6 T600A) exhibited a diminished capacity to bind S100A10, were redistributed to a subplasma membrane area and did not display channel activity. Using GST pull‐down and co‐immunoprecipitation assays we demonstrated that annexin 2 is part of the TRPV5–S100A10 complex. Furthermore, the S100A10–annexin 2 pair colocalizes with the Ca2+ channels in TRPV5‐expressing renal tubules and TRPV6‐expressing duodenal cells. Importantly, downregulation of annexin 2 using annexin 2‐specific small interfering RNA inhibited TRPV5 and TRPV6‐mediated currents in transfected HEK293 cells. In conclusion, the S100A10–annexin 2 complex plays a crucial role in routing of TRPV5 and TRPV6 to plasma membrane.

Castration resistance in prostate cancer (PCa) constitutes an advanced, aggressive disease with poor prognosis, associated with uncontrolled cell proliferation, resistance to apoptosis, and enhanced invasive potential. The molecular mechanisms involved in the transition of PCa to castration resistance are obscure. Here, we report that the nonselective cationic channel transient receptor potential vanilloid 2 (TRPV2) is a distinctive feature of castration-resistant PCa. TRPV2 transcript levels were higher in patients with metastatic cancer (stage M1) compared with primary solid tumors (stages T2a and T2b). Previous studies of the TRPV2 channel indicated that it is primarily involved in cancer cell migration and not in cell growth. Introducing TRPV2 into androgen-dependent LNCaP cells enhanced cell migration along with expression of invasion markers matrix metalloproteinase (MMP) 9 and cathepsin B. Consistent with the likelihood that TRPV2 may affect cancer cell aggressiveness by influencing basal intracellular calcium levels, small interfering RNA–mediated silencing of TRPV2 reduced the growth and invasive properties of PC3 prostate tumors established in nude mice xenografts, and diminished expression of invasive enzymes MMP2, MMP9, and cathepsin B. Our findings establish a role for TRPV2 in PCa progression to the aggressive castration-resistant stage, prompting evaluation of TRPV2 as a potential prognostic marker and therapeutic target in the setting of advanced PCa. Cancer Res; 70(3); 1225–35

In recent years, the transient receptor potential melastatin member 8 (TRPM8) channel has emerged as a promising prognostic marker and putative therapeutic target in prostate cancer (PCa). However, the mechanisms of prostate-specific regulation and functional evolution of TRPM8 during PCa progression remain unclear. Here we show, for the first time to our knowledge, that only secretory mature differentiated human prostate primary epithelial (PrPE) luminal cells expressed functional plasma membrane TRPM8 (_PMTRPM8) channels. Moreover, PCa epithelial cells obtained from in situ PCa were characterized by a significantly stronger _PMTRPM8-mediated current than that in normal cells. This _PMTRPM8 activity was abolished in dedifferentiated PrPE cells that had lost their luminal secretory phenotype. However, we found that in contrast to _PMTRPM8, endoplasmic reticulum TRPM8 (_ERTRPM8) retained its function as an ER Ca²⁺ release channel, independent of cell differentiation. We hypothesize that the constitutive activity of _ERTRPM8 may result from the expression of a truncated TRPM8 splice variant. Our study provides insight into the role of TRPM8 in PCa progression and suggests that TRPM8 is a potentially attractive target for therapeutic intervention: specific inhibition of either _ERTRPM8 or _PMTRPM8 may be useful, depending on the stage and androgen sensitivity of the targeted PCa.