Capacitative Ca2+ entries and mRNA expression for TRPC1 and TRPC5 channels in human epidermoid carcinoma A431 cells

In human epidermoid carcinoma A431 cells, capacitative Ca2+ entries in response to intracellular Ca2+ store depletion with thapsigargin, an endoplasmic reticulum Ca(2+)-ATPase inhibitor, and uridine 5'-triphosphate, a phospholipase C-linked agonist, were inhibited by trivalent cations such as Gd3+ and La3+, and by the store-operated Ca2+ channel inhibitor, 2-aminoethoxydiphenyl borate. Of the seven types of canonical transient receptor potential (TRPC) channels as molecular candidates for store-operated Ca2+ channels, mRNAs for TRPC1 and TRPC5 were detected in the cells with the reverse transcription-polymerase chain reaction. Western blotting confirmed the protein expressions of TRPC1 and TRPC5 in A431 cells. The present results suggest that TRPC1 and/or TRPC5 channels serve as store-operated Ca2+ channels in A431 cells, and may function as regulators for intracellular Ca2+ signaling.