Primary aldosteronism (PA) is characterized by aldosterone hypersecretion and adrenal hyperplasia and ranks as one of the most common causes of secondary hypertension. However, the molecular mechanism involved in adrenal hyperplasia and tumorigenesis is largely unknown. Dysregulation of Purkinji cell protein 4 (PCP4) is involved in the development and progression of neoplasia and aldosterone secretion, but little is known about the effect of PCP4 on human adrenocortical tumorigenesis. We investigated the expression pattern of PCP4 in different adrenal tissues and studied whether PCP4 is involved in cell growth in human adrenal cell lines. The mRNA levels of PCP4 were measured by real-time PCR in tissues from aldosterone-producing adenomas (APAs), idiopathic hyperaldosteronism (IHA) tissues, and normal adrenal (NA) tissues. In vitro siRNA knockdown of PCP4 in NCI-H295R and SW13 cell lines was used to determine the effect of PCP4 on cellular growth. Our results show that the mRNA level of PCP4 is upregulated in APAs and IHA compared with that in NA. The PCP4 mRNA expression level was positively correlated with tumor size in APAs. Knockdown of PCP4 decreased cell proliferation. Flow cytometry analysis showed that PCP4 knockdown fosters apoptosis. Finally, PCP4 knockdown inhibited phosphorylation of AKT308 and AMPKThr172. Our data suggest that PCP4 may represent a key player in the development and pathophysiology of PA via targeting the AKT and AMPK signaling pathways and thus may be a promising therapeutic target for PA.
Keywords: Purkinji cell protein 4; adrenocortical cell proliferation; aldosterone-producing adenoma; apoptosis; primary aldosteronism.
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