Octyl syringate is preferentially cytotoxic to cancer cells via lysosomal membrane permeabilization and autophagic flux inhibition.

The autophagy-mediated lysosomal pathway plays an important role in conferring stress tolerance to tumor cells during cellular stress such as increased metabolic demands. Thus, targeted disruption of this function and inducing lysosomal cell death have been proved to be a useful cancer therapeutic approach. In this study, we reported that octyl syringate (OS), a novel phenolic derivate, was preferentially cytotoxic to various cancer cells but was significantly less cytotoxic to non-transformed cells. Treatment with OS resulted in non-apoptotic cell death in a caspase-independent manner. Notably, OS not only enhanced accumulation of autophagic substrates, including lapidated LC3 and sequestosome-1, but also inhibited their degradation via an autophagic flux. In addition, OS destabilized the lysosomal function, followed by the intracellular accumulation of the non-digestive autophagic substrates such as bovine serum albumin and stress granules. Furthermore, OS triggered the release of lysosomal enzymes into the cytoplasm that contributed to OS-induced non-apoptotic cell death. Finally, we demonstrated that OS was well tolerated and reduced tumor growth in mouse xenograft models. Taken together, our study identifies OS as a novel anticancer agent that induces lysosomal destabilization and subsequently inhibits autophagic flux and further supports development of OS as a lysosome-targeting compound in cancer therapy. • Octyl syringate, a phenolic derivate, is preferentially cytotoxic to various cancer cells. • Octyl syringate destabilizes the lysosomal function. • Octyl syringate blocks the autophagic flux. • Octyl syringate is a potential candidate compound for cancer therapy.

Rbfox family proteins make the homo- and hetero-oligomeric complexes.

Rbfox family of proteins that consists of Rbfox1, Rbfox2, and Rbfox3 in mammals regulates alternative pre-mRNA splicing in various tissues via direct binding to their RNA binding element. Although many studies have indicated the splicing activity of each member of the Rbfox family, the interactions of Rbfox family proteins are largely unknown. Here, we have investigated interactions among Rbfox family proteins. Co-immunoprecipitation (Co-IP) and GST-pull down assays confirmed that Rbfox proteins form homo and hetero complexes. Moreover, in vivo crosslinking using disuccinimidyl suberate treatment indicated that the Rbfox proteins form a dimer which then assembles with other proteins to form a large multiprotein complex. Duolink in situ proximity ligation (PLA) assay revealed that neuron specific Rbfox3 protein interacts with other Rbfox family proteins. This study is the first to provide an evidence that Rbfox family proteins form homo- and hetero-oligomeric complexes in vivo.

Bortezomib, a proteasome inhibitor, alleviates atopic dermatitis by increasing claudin 1 protein expression.

Atopic dermatitis (AD) is a chronic inflammatory skin disease. Many studies investigating AD pathogenesis and its therapy have been conducted but none have been successful. One of the causes of AD is dysfunction of tight junctions through reduction of claudin 1 expression in the epidermal barrier of the skin. In the present study, we investigated the role of bortezomib (BTZ) in the restoration of the reduced expression of claudin 1. Immunoblot and immunofluorescence analyses revealed that BTZ increased the protein expression level of claudin 1 in the human keratinocyte cell line HaCaT, thereby forming paracellular barriers. Furthermore, repeated application of BTZ alleviated atopic symptoms on the backs and ears of 2, 4-dinitrochlorobenzene (DNCB)-induced AD mice, and led to the formation of normal tight junctions in the epidermal barrier of DNCB-induced mice skin. Taken together, these results demonstrate that BTZ-induced claudin 1 expression may be a valuable therapeutic approach for AD.

Alpha-Casein and Beta-Lactoglobulin from Cow Milk Exhibit Antioxidant Activity: A Plausible Link to Antiaging Effects.

Studies on the discovery and function of antioxidants are consistently being performed because oxidative stress can cause various diseases. Many compounds and natural products have antioxidant activity in vitro; however, it is often difficult to reproduce their effects in vivo. Additionally, methods to measure antioxidant activities in cells are also scarce. Here, we investigated the antioxidant activity of milk proteins by observing the formation of arsenite-induced stress granules as a tool to evaluate antioxidant activity in cells. Milk proteins not only decreased the formation of stress granules in several cell types but also scavenged 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cations in vitro. In addition, milk proteins inhibited cellular senescence based on an SA-ß-galactosidase assay, and increased differentiation to myotubes from myoblasts isolated from the skeletal muscles of mouse pups. Taken together, our results demonstrate that milk proteins have an antiaging effect, especially prevention of skeletal muscle loss, through their antioxidant activities. PRACTICAL APPLICATION: Our results provide that antioxidant effects of milk proteins containing α-caseins, ß-caseins, and ß-lactoglobulin can mitigate aging-related damage induced by oxidative stress through showing inhibition of cellular senescence and increase of differentiation and maturation of myoblast. Therefore, we suggest that milk proteins could be potent health supplements to prevent aging-associated diseases, especially sarcopenia.