NRSN2 promotes the malignant behavior of HPV-transfected laryngeal carcinoma cells through AMPK/ULK1 pathway mediated autophagy activation

Neurensin-2 (NRSN2) performs a pro-carcinogenic function in multiple cancers. However, the function of NRSN2 in HPV-infected laryngeal carcinoma (LC) remains unclear. HPV transfection was performed in LC cells. The mRNA and protein levels were monitored using RT-qPCR, immunoblotting, and IF. Cell viability and proliferation were found using the CCK-8 assay and Edu staining. Cell invasion, migration, and apoptosis were probed using the Transwell, wound healing, and flow cytometry, respectively. The autophagosome was observed using TEM. NRSN2 was overexpressed in HPV-transfected LC cells. Inhibition of NRSN2 restrained the autophagy and malignant behavior of HPV-transfected LC cells. Meanwhile, the inhibition of AMPK/ULK1 pathway limited the increased autophagy of HPV-transfected LC cells caused by NRSN2 overexpression. Furthermore, NRSN2 knockdown inhibits autophagy by suppressing AMPK/ULK1 pathway, thereby restraining the malignant behavior of HPV-transfected LC cells. Our research confirmed that HPV transfection increased the autophagy and malignant behavior of LC cells by regulating the NRSN2-mediated activation of the AMPK/ULK1 pathway, offering a new target for cure of LC.

EGCG Restores Keratinocyte Autophagy to Promote Diabetic Wound Healing through the AMPK/ULK1 Pathway

BACKGROUND

Delayed wound healing, a common problem in patients with diabetes mellitus (DM), is associated with impaired keratinocyte autophagy. Epigallocatechin gallate (EGCG), a catechin, has been proven to promote diabetic wound healing. This study aims to explore the therapeutic mechanism of EGCG on diabetic wound healing.

METHODS

High glucose (HG)-induced keratinocytes and streptozotocin (STZ)-induced DM rats were prepared and intervened with EGCG to examine its therapeutic effects in in vivo and in vitro settings. The AMPK inhibitor, Compound C, was utilized to determine whether EGCG exerted its therapeutic effects through the AMPK/ULK1 pathway.

RESULTS

In vitro, EGCG improved HG-induced autophagy impairment in keratinocytes by increasing LC3II/LC3I, Becline1, and ATG5 levels and decreasing p62 level. Mechanically, EGCG activated the AMPK/ULK1 pathway, thereby promoting keratinocyte autophagy through the phosphorylation of AMPK and ULK1. Notably, EGCG promoted the proliferation, migration, synthesis and release of C-C motif chemokine ligand 2 (CCL2) in HG-treated keratinocytes. Furthermore, EGCG indirectly promoted the activation of fibroblasts, as evidenced by increased alpha-smooth muscle actin (α-SMA) and Collagen I levels. In vivo, EGCG promoted wound healing in DM rats, primarily by reducing inflammatory infiltration and increasing granulation tissue to promote wound epithelialization. Besides, EGCG promoted ATG5, KRT10, KRT14, TGF-β1, Collagen I, and α-SMA expressions in the neonatal epithelial tissues of DM rats. However, the use of Compound C reversed the effects of EGCG.

CONCLUSIONS

These findings indicated that EGCG restored keratinocyte autophagy to promote diabetic wound healing through the AMPK/ULK1 pathway.

iPSCs ameliorate hypoxia-induced autophagy and atrophy in C2C12 myotubes via the AMPK/ULK1 pathway

BACKGROUND

Duchenne muscular dystrophy (DMD) is an X-linked lethal genetic disorder for which there is no effective treatment. Previous studies have shown that stem cell transplantation into mdx mice can promote muscle regeneration and improve muscle function, however, the specific molecular mechanisms remain unclear. DMD suffers varying degrees of hypoxic damage during disease progression. This study aimed to investigate whether induced pluripotent stem cells (iPSCs) have protective effects against hypoxia-induced skeletal muscle injury.

RESULTS

In this study, we co-cultured iPSCs with C2C12 myoblasts using a Transwell nested system and placed them in a DG250 anaerobic workstation for oxygen deprivation for 24 h. We found that iPSCs reduced the levels of lactate dehydrogenase and reactive oxygen species and downregulated the mRNA and protein levels of BAX/BCL2 and LC3II/LC3I in hypoxia-induced C2C12 myoblasts. Meanwhile, iPSCs decreased the mRNA and protein levels of atrogin-1 and MuRF-1 and increased myotube width. Furthermore, iPSCs downregulated the phosphorylation of AMPKα and ULK1 in C2C12 myotubes exposed to hypoxic damage.

CONCLUSIONS

Our study showed that iPSCs enhanced the resistance of C2C12 myoblasts to hypoxia and inhibited apoptosis and autophagy in the presence of oxidative stress. Further, iPSCs improved hypoxia-induced autophagy and atrophy of C2C12 myotubes through the AMPK/ULK1 pathway. This study may provide a new theoretical basis for the treatment of muscular dystrophy in stem cells.

Ebastine exerts antitumor activity and induces autophagy by activating AMPK/ULK1 signaling in an IPMK-dependent manner in osteosarcoma

Numerous studies have confirmed that in addition to interfering with the tumor inflammatory environment, anti-inflammatory agents can directly increase apoptosis and sensitivity to conventional therapies and decrease invasion and metastasis, making them useful candidates for cancer therapy. Here, we first used high-throughput screening and had screened one compound candidate, ebastine (a H1-histamine receptor antagonist), for osteosarcoma therapy. Cell viability assays, colony formation assays, wound healing assays, and Transwell assays demonstrated that ebastine elicited antitumor effects in osteosarcoma cells. In addition, ebastine treatment exerted obvious effects on cell cycle arrest, metastasis inhibition, apoptosis and autophagy induction both in vitro and in vivo. Mechanistically, we observed that ebastine treatment triggered proapoptotic autophagy by activating AMPK/ULK1 signaling in osteosarcoma cells. Treatment with the AMPK inhibitor dorsomorphin reversed ebastine-induced apoptosis and autophagy. More importantly, we found that IPMK interacted with AMPK and functioned as a positive regulator of AMPK protein in osteosarcoma cells. A rescue study showed that the induction of autophagy and activation of the AMPK/ULK1 signaling pathway by ebastine treatment were reversed by IPMK knockdown, indicating that the activity of ebastine was IPMK dependent. We provide experimental evidence demonstrating that ebastine has antitumor activity in osteosarcoma and promotes autophagy by activating the AMPK/ULK1 signaling pathway, which is IPMK dependent. Our results provide insight into the clinical application potential of ebastine, which may represent a new potential therapeutic candidate for the treatment of osteosarcoma.

Aconitine induces autophagy via activating oxidative DNA damage-mediated AMPK/ULK1 signaling pathway in H9c2 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Aconitum species, with a medicinal history of 2000 years, was traditionally used in the treatment of rheumatism, arthritis, bruises, and pains. However, many studies have reported that Aconitum species can cause arrhythmia in experimental animals, resulting in myocardial fibrosis and cardiomyocyte damage. Cardiotoxicity is the main toxic effect of aconitine, but the detailed mechanism remains unclear.

AIM OF THE STUDY

This study aimed to explore the effects and underlying mechanism of autophagy in H9c2 cardiomyocytes induced by aconitine.

MATERIALS AND METHODS

H9c2 cells were incubated with different concentrations of aconitine for 24 h, and the intervention sections were pretreated with various inhibitors for 1 h. The effects of aconitine on the oxidative DNA damage, autophagy and viability of H9c2 cells were evaluated by flow cytometry, confocal microscopy, enzyme-linked immunosorbent assay and Western blot.

RESULTS

In H9c2 cells, the cell viability declined, LDH release rate, the number of autophagosomes, protein expression levels of LC3 and Beclin-1 increased significantly after 24 h of aconitine incubation. The pretreatment of autophagy inhibitor 3-MA decreased markedly autophagosomes and protein expression levels of LC3 and Beclin-1, which suggested that aconitine could induce cell autophagy. The significant increase of ROS and 8-OHdG showed that aconitine could cause oxidative DNA damage through ROS accumulation. Meanwhile, treatment of aconitine dramatically increased AMPK^Thr172 and ULK1^Ser317 phosphorylation, and Compound C inhibited AMPK^Thr172 and ULK1^Ser317 phosphorylation, which proved that aconitine induced autophagy via AMPK activation mediated ULK1 phosphorylation. Antioxidant NAC significantly reduced LDH, ROS and 8-OHdG, inhibited the phosphorylation of AMPK^Thr172 and ULK1^Ser317, and down-regulated autophagosomes and proteins expression levels of LC3 and Beclin-1. Consequently, the inhibition of oxidative DNA damage and AMPK/ULK1 signaling pathway alleviated the aconitine-induced autophagic death of H9c2 cells.

CONCLUSIONS

These results showed that aconitine induces autophagy of H9c2 cardiomyocytes by activating AMPK/ULK1 signaling pathway mediated by oxidative DNA damage. The autophagy induced by aconitine in cardiomyocytes is dependent on the activation of the AMPK pathway, which may provide novel insights into the prevention of aconitine-related toxicity.