Human ether‑à‑go‑go‑related gene mutation L539fs/47‑hERG leads to cell apoptosis through the endoplasmic reticulum stress pathway

Withaferin A-Encapsulated PEGylated Nanoliposomes Induce Apoptosis in B16F10 Melanoma Cells by Regulating Bcl2 and Bcl xl Genes and Mitigates Murine Solid Tumor Development

Withaferin A (WA) is a natural steroidal lactone with promising pharmacological activities, but its poor solubility and bioavailability hinder its clinical application. The liposomal drug delivery system has attracted considerable attention to overcome the delivery limitations of pharmacological agents. The present study investigated the effect of WA-loaded pegylated nanoliposomes (LWA) on in vitro and in vivo B16F10 melanoma tumor models. In vitro results showed that LWA had significantly (P < 0.01) higher cytotoxicity than free WA and induced ROS-mediated apoptosis in B16F10 cells. Transwell cell migration and invasion studies demonstrated that LWA treatment significantly (P < 0.01) decreased the migratory and invasive capacities of melanoma cells compared with WA. In vivo study revealed that treatment significantly (P < 0.01) reduced tumor growth in experimental animals compared with WA or tumor control. Also, LWA administration remarkably inhibited tumor cell proliferation by downregulating the expression of Ki-67 and Cyclin D1 and induced apoptosis by regulating the expression of Bax, Bcl2, and Bcl xl levels. Our results strongly suggest that LWA could be a promising therapeutic formulation for treating malignant melanoma.

KCNH2A561V Heterozygous Mutation Inhibits KCNH2 Protein Expression via The Activation of UPR Mediated by ATF6

The potassium channel protein KCNH2 is encoded by KCNH2 gene, and there are more than 300 mutations of KCNH2. Unfolded protein response (UPR) is typically initiated in response to an accumulation of unfolded and/or misfolded proteins in the endoplasmic reticulum (ER). The present study aimed to explore the UPR process and the role of activating transcription factor 6 (ATF6) in the abnormal expression of potassium voltage-gated channel subfamily H member 2 (KCNH2)A561V. The wild-type (wt) KCNH2 and A561V mutant KCNH2 was constructed with his-tag. The 293 cells were used and divided into KCNH2wt+KCNH2A561V, KCNH2wt and KCNH2A561V groups. The expression levels of ATF6 and KCNH2 in different groups were detected by Western blotting, reverse transcription-quantitative PCR, immunofluorescence and immuno-coprecipitation assays. The protein types and abundance of immuno-coprecipitation samples were analyzed by mass spectrometry. The proteomic analysis of the mass spectrometry results was carried out by using the reactome database and GO (Gene Ontology) tool. The mRNA expression levels of KCNH2 and ATF6 in the KCNH2wt+KCNH2A561V group were higher compared with the KCNH2A561V group. However, the full-length protein expression of ATF6 was inhibited, indicating that ATF6 was highly activated and a substantial number of ATF6 was sheared in KCNH2wt+KCNH2A561V group compared with control group. Furthermore, A561V-KCNH2 mutation leading to the accumulation of the immature form of KCNH2 (135 kDa bands) in ER, resulting in the reduction of the ratio of 155 kDa/135 kDa. In addition, the abundance of UPR-related proteins in the KCNH2A561V group was higher compared with the KCNH2wt+KCNH2A561V group. The 'cysteine biosynthetic activity' of GO:0019344 process and the 'positive regulation of cytoplasmic translation activity' of GO:2000767 process in the KCNH2A561V group were higher compared with the KCNH2wt+KCNH2A561V group. Hence, co-expression of wild-type and A561V mutant KCNH2 in 293 cells activated the UPR process, which led to the inhibition of protein translation and synthesis, in turn inhibiting the expression of KCNH2. These results provided a theoretical basis for clinical treatment of Long QT syndrome.