Cancer cells are characterized by malignant proliferation and aberrant metabolism and are thereby liable to the depletion of nutrients and accumulation of metabolic waste. To maintain cellular homeostasis, cancer cells are prone to upregulating the canonical autophagy pathway. Here, we identified paroxetine hydrochloride (Paxil) as a late autophagy inhibitor and investigated its killing effect on lung cancer cells and with a xenograft mouse model in vivo. Upregulated LC3-II and p62 expression indicated that Paxil inhibited autophagy. Acid-sensitive dyes (e.g., LysoTracker and AO staining) indicated reduced lysosomal acidity following Paxil treatment; consequently, the maturation of the pH-dependent hydroxylases (e.g., cathepsin B and D) substantially declined. Paxil also induced the fragmentation of mitochondria and further intensified ROS overproduction. Since the autophagy pathway was blocked, ROS rapidly accumulated, which activated JNK and p38 kinase. Such activity promoted the localization of Bax, which led to increased mitochondrial outer membrane permeability. The release of Cytochrome c with the loss of the membrane potential triggered a caspase cascade, ultimately leading to apoptosis. In contrast, the clearance of ROS by its scavenger, NAC, rescued Paxil-induced apoptosis accompanied by reduced p38 and JNK activation. Thus, Paxil blocked the autophagic flux and induced the mitochondria-dependent apoptosis via the ROS-MAPK pathway.

Dioscin is a natural steroidal saponin that can be isolated from Chinese medicine, such as Dioscoreae rhizoma. It has wild range of pharmacological activities such as hepatoprotection, a lipid-lowering effect, and anti-inflammation. Recently, mounting studies reported the anticancer effect of dioscin on a variety of tumor cells. However, the potential effect of dioscin on the epithelial-mesenchymal transition (EMT) of HepG2 cells is unclear. In the present study, dioscin was identified to inhibit transforming growth factor-β1 (TGF-β1) and induced invasive and migratory behavior of HepG2 cells. Consistently, the expression of the epithelial marker E-cadherin and gap junction proteins increased following dioscin treatment, while mesenchymal markers decreased, including N-cadherin, Vimentin, Snail, and Slug. Furthermore, we discovered that TGF-β1 induces phosphorylation of JNK, p38, and Erk, whereas the activation of these kinases was reversed by dioscin treatment in a dose-dependent manner. With the addition of Asiatic acid, a p38 activator, the inhibitory effect of dioscin on EMT was reversed. Taken together, these data indicated that dioscin inhibits EMT in HepG2 cells, which is mediated in large part by inhibition of the p38-MAPK signaling.

No abstract

The cochlea consists of multiple types of cells, including hair cells, supporting cells and spiral ganglion neurons, and is responsible for converting mechanical forces into electric signals that enable hearing. Genetic and environmental factors can result in dysfunctions of cochlear and auditory systems. In recent years, gene therapy has emerged as a promising treatment in animal deafness models. One major challenge of the gene therapy for deafness is to effectively deliver genes to specific cells of cochleae. Here, we screened and identified an AAV-ie mutant, AAV-ie-K558R, that transduces hair cells and supporting cells in the cochleae of neonatal mice with high efficiency. AAV-ie-K558R is a safe vector with no obvious deficits in the hearing system. We found that AAV-ie-K558R can partially restore the hearing loss in Prestin KO mice and, importantly, deliver Atoh1 into cochlear supporting cells to generate hair cell-like cells. Our results demonstrate the clinical potential of AAV-ie-K558R for treating the hearing loss caused by hair cell death.