Morphologic evaluation and CYP11B2 IHC enabled the classification of cross-sectional image-negative hyperaldosteronism into MN and DH. Somatic mutations driving aldosterone overproduction are common in micronodules of MN, suggesting a histological entity possibly related to aldosterone-producing cell cluster development.
CYP11B1 and CYP11B2 play pivotal roles in adrenocorticosteroids synthesis. We performed semi-quantitative immunohistochemical analysis of these proteins in adrenals from patients with primary aldosteronism using novel monoclonal antibodies. Clusters of cortical cells positive for CYP11B2 were detected in the zona glomerulosa (ZG) of normal adrenal gland (NA), idiopathic hyperaldosteronism (IHA) and the adjacent adrenal of aldosterone-producing adenoma (APA). In APA, heterogenous immunolocalization of CYP11B2 and diffuse immunoreactivity of CYP11B1 were detected in tumor cells, respectively. The relative immunoreactivity of CYP11B2 in the ZG of adjacent adrenal of APA was significantly lower than that of NA, IHA and APA tumor cells, suggestive of suppressed aldosterone biosynthesis in these cells. These findings did indicate the regulatory mechanisms of aldosterone biosynthesis were different between normal/hyperplastic and neoplastic aldosterone-producing cells in human adrenals. CYP11B2 immunoreactivity in the ZG could also serve as a potential immunohistochemical marker differentiating morphologically hyperplastic ZG of IHA and APA adjacent adrenal.
It has become important to evaluate the possible involvement of 3β-hydroxysteroid dehydrogenase type 1 (HSD3B1) and 2 (HSD3B2) isoforms in aldosterone-producing adenoma (APA). In this study, we studied 67 and 100 APA cases using real-time quantitative PCR (qPCR) and immunohistochemistry, respectively. Results of qPCR analysis demonstrated that HSD3B2 mRNA was significantly more abundant than HSD3B1 mRNA (P < 0.0001), but only HSD3B1 mRNA significantly correlated with CYP11B2 (aldosterone synthase) mRNA (P < 0.0001) and plasma aldosterone concentration (PAC) of the patients (P < 0.0001). Results of immunohistochemistry subsequently revealed that HSD3B2 immunoreactivity was detected in the great majority of APA but a significant correlation was also detected between HSD3B1 and CYP11B2 (P < 0.0001). In KCNJ5 mutated APA, CYP11B2 mRNA (P < 0.0001) and HSD3B1 mRNA (P = 0.011) were significantly higher than those of wild type APA. These results suggest that HSD3B1 is involved in aldosterone production, despite its lower levels of expression compared with HSD3B2, and also possibly associated with KCNJ5 mutation in APA.
The development of therapeutic resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs, ie erlotinib or gefitinib) has been the major clinical problem when treating lung adenocarcinoma patients with these agents. However, its mechanisms have not necessarily been well studied to this date. Autophagy has been recently considered to play pivotal roles in escaping from the effects of anti-neoplastic agents. Therefore, in this study, we examined its roles in the development of resistance to EGFR-TKIs in lung adenocarcinoma. We first established erlotinib-resistant cell lines (PC9/ER) from parental PC9 cells by exposing the cells to erlotinib. In PC9/ER, autophagy-related LC3A expression came to be up-regulated and constitutive activation of LC3A-mediated autophagy became more pronounced through the process of acquiring therapeutic resistance. In addition, inhibition of LC3A or autophagy restores sensitivity to EGFR-TKIs in PC9/ER. LC3A was also activated at the transcriptional level in de novo resistant cells via demethylation of the MAP1LC3A gene. We then evaluated the status of LC3A in 169 lung adenocarcinoma patients using immunohistochemistry. LC3A immunoreactivity was only detected in carcinoma cells (89/169 patients), not in non-tumoural cells. In addition, LC3A immunoreactivity was significantly correlated with progression-free survival (p = 0.0039) and overall survival (p = 0.0040) of 35 patients treated with EGFR-TKIs. The results of our present study demonstrated that LC3A-mediated autophagy in carcinoma cells was involved in the development of resistance to EGFR-TKIs, and that LC3A could serve as a promising therapeutic target for overcoming resistance to EGFR-TKIs and a novel predictor of response to EGFR-TKIs in lung adenocarcinoma patients.
Purkinje cell protein 4 (PCP4) is a calmodulin (CaM) binding protein that accelerates calcium association and dissociation with CaM. It has been previously detected in aldosterone-producing adenomas (APA) but details on its expression and function in adrenocortical tissues have remained unknown. Therefore, we performed the immunohistochemical analysis of PCP4 in the following tissues: normal adrenal (NA; n=15), APA (n=15), cortisol producing adenomas (CPA; n=15) and idiopathic hyperaldosteronism cases (IHA; n=5). APA samples (n=45) were also submitted to quantitative RT-PCR (qPCR) of PCP4, CYP11B1, and CYP11B2, as well as DNA sequencing for KCNJ5 mutations. Transient transfection analysis using PCP4 siRNA was also performed in H295R adrenocortical carcinoma cells, following ELISA analysis, and CYP11B2 luciferase assays were also performed after PCP4 vector transfection in order to study the regulation of PCP4 protein expression. In our findings, PCP4 immunoreactivity was predominantly detected in APA and in the zona glomerulosa (ZG) of NA and IHA. In APA, the mRNA levels of PCP4 were significantly correlated with those of CYP11B2 (P<0.0001) and were significantly higher in cases with KCNJ5 mutation than wild-type (P=0.005). Following PCP4 vector transfection, CYP11B2 luciferase reporter activity was significantly higher than controls in the presence of angiotensin-II. Knockdown of PCP4 resulted in a significant decrease in CYP11B2 mRNA levels (P=0.012) and aldosterone production (P=0.011). Our results indicate that PCP4 is a regulator of aldosterone production in normal, hyperplastic and neoplastic human adrenocortical cells.
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