Endocrine Abstracts

The cyclic AMP (cAMP) signalling cascade is one of the main pathways involved in the pathogenesis of adrenocortical tumors (ACT). PRKARIA or PRKARIIb are involved in the proliferation/apoptosis in a subset of tumors.

Majors alterations of genes involved in both cell proliferation and the cell cycle have been described by transcriptome and miRNome analysis in various types of adrenocortical tumors (ACC, ACA, AIMAH, and PPNAD). In addition to tumor growth for malignant tumors, steroid excess causes morbidity in patients with all types of ACT.

The goal of this study is to find whether there is a correlation between the cell cycle and the steroidogenesis.

Methods: We have studied the cell cycle distribution (FACS) and the expression of the steroidogenic enzymes (western blot, and RT-qPCR) in i) H295R cell line after inactivation of PRKAR1A or PRKARIIb using RNA interference ii) synchronized H295R cell line, and iii) PPNAD cells in primary cell culture. We used pharmacologic drugs to arrest cells at specific cell cycle check point: L-mimosine (G1 phase), aphidicolin (S phase), and nocodazole (G2 phase). The expression of the different actors of cell cycle regulation as cyclins and cdks, and signalling pathways were studied.

Results: The decrease of either R1α or R2β protein enhances the accumulation of cells in G2 phase, and Cyp17A, Cyp11B1 and Cyp11B2 levels. The synchronization of both the H295R (ACC cells) or PPNAD primary cell culture at G2 phase increased the expression of the steroidogenic enzymes. In PPNAD this increase started at the S phase. Arresting both H295R and PPNAD cells in G1 phase decreases the steroidogenic enzymes expression, resulting in a decrease in cortisol secretion.

Conclusion: We have found a correlation between the cell cycle check point and the expression of steroidogenic enzymes. Targeting specific cell cycle check point may down regulate the hyper secretion of steroids in these tumors.