Store-operated calcium (Ca2+) entry (SOCE) is the principal Ca2+ entry route in non-excitable cells, including cancer cells. We previously demonstrated that Orai1 and STIM1, the molecular components of SOCE, are involved in tumorigenesis of clear cell renal cell carcinoma (CCRCC). However, a clinical relevance of Orai1 and STIM1 expression in CCRCC has been ill-defined. Here, we investigated the expression of Orai1 and STIM1 in CCRCC, and compared their expression with clinico-pathological parameters of CCRCC and the patients' outcome. Immunohistochemical staining for Orai1 and STIM1 was performed on 126 formalin fixed paraffin embedded tissue of CCRCC and western blot analysis for Orai1 was performed on the available fresh tissue. The results were compared with generally well-established clinicopathologic prognostic factors in CCRCC and patient survival. Membrane protein Orai1 is expressed in the nuclei in CCRCC, whereas STIM1 shows the cytosolic expression pattern in immunohistochemical staining. Orai1 expression level is inversely correlated with CCRCC tumor grade, whereas STIM1 expression level is not associated with tumor grade. The higher Orai1 expression is significantly associated with lower Fuhrman nuclear grade, pathologic T stage, and TNM stage and with favorable prognosis. The expression level of STIM1 is not correlated with CCRCC grade and clinical outcomes. Orai1 expression in CCRCC is associated with tumor progression and with favorable prognostic factors. These results suggest that Orai1 is an attractive prognostic marker and therapeutic target for CCRCC.
Adolescent ; Adult ; Aged ; Blotting, Western ; Carcinoma, Renal Cell/*diagnosis/metabolism/*pathology ; Female ; *Gene Expression Regulation, Neoplastic ; Humans ; Immunohistochemistry ; Kidney Neoplasms/metabolism/*pathology ; Male ; Middle Aged ; Neoplasm Proteins/genetics/metabolism ; ORAI1 Protein/genetics/*metabolism ; Prognosis ; Retrospective Studies ; Stromal Interaction Molecule 1/genetics/metabolism ; Young Adult

OBJECTIVETo explore the effects of stromal interaction molecule 1 (STIM1) on the expression of apoptosis-related proteins in prostate cancer PC-3 cells.

METHODSWe transfected the lentivirus vector STIM1-pGCSIL-GFP carrying STIM shRNA into human hormone-independent prostate cancer PC-3 cells, and 3 days later observed the transfection efficiency by fluorescence microscopy. At 7 days after transfection, we determined the expression of STIM1 in the PC-3 cells by RT-PCR and Western blot and those of apoptosis-related proteins Bcl-2, Bax, survivin and activated Caspase-3 by Western blot.

RESULTSAt 3 days, inverted microscopy revealed a transfection efficiency of > 80%. At 7 days, the STIM1 expression was significantly inhibited at both mRNA and protein levels. The Bcl-2/Bax rate was remarkably decreased as compared with that of the control group (0. 31 vs 1.24 ) , and the survivin expression was markedly reduced, 0. 14 times that of the relative expression in the control. However, the Caspase-3 cleavage was significantly activated, 1.52 times that of the control (P <0.05).

CONCLUSIONSTIM1 can be regarded as an oncogene in prostate cancer PC-3 cells. Inhibition of its expression can induce PC-3 cell apoptosis by reducing the Bcl-2/Bax rate, decreasing the survivin expression, and activating the Caspase-3 pathway.

Apoptosis ; Caspase 3 ; metabolism ; Cell Line, Tumor ; Humans ; Inhibitor of Apoptosis Proteins ; metabolism ; Male ; Membrane Proteins ; genetics ; Neoplasm Proteins ; genetics ; Prostatic Neoplasms ; metabolism ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; RNA, Small Interfering ; genetics ; Stromal Interaction Molecule 1 ; Transfection ; bcl-2-Associated X Protein ; metabolism