Human BECN1 (Beclin-1) ELISA Kit

Experimental evidence demonstrated that macroautophagy/autophagy exerts a crucial role in maintain renal cellular homeostasis and represents a protective mechanism against renal injuries. Interestingly, it has been demonstrated that in the human proximal tubular renal cell line, HK-2, the MTOR inhibitor rapamycin enhanced autophagy and mitigated the apoptosis damage induced by urinary protein overload. However, the underlying molecular mechanism has not yet been elucidated. In our study we demonstrated, for the first time, that in HK-2 cells, the exposure to low doses of rapamycin transactivated the NGFR promoter, leading to autophagic activation. Indeed, we observed that in HK-2 cells silenced for the NGFR gene, the rapamycin-induced autophagic process was prevented, as the upregulation of the proautophagic markers, BECN1, as well as LC3-II, and the autophagic vacuoles evaluated by transmission electron microscopy, were not found. Concomitantly, using a series of deletion constructs of the NGFR promoter we found that the EGR1 transcription factor was responsible for the rapamycin-mediated transactivation of the NGFR promoter. Finally, our results provided evidence that the cotreatment with rapamycin plus albumin further enhanced autophagy via NGFR activation, reducing the proapoptotic events promoted by albumin alone. This effect was prevented in HK-2 cells silenced for the NGFR gene or pretreated with the MTOR activator, MHY1485. Taken together, our results describe a novel molecular mechanism by which rapamycin-induced autophagy, mitigates the tubular renal damage caused by proteinuria, suggesting that the use of low doses of rapamycin could represent a new therapeutic strategy to counteract the tubule-interstitial injury observed in patients affected by proteinuric nephropathies, avoiding the side effects of high doses of rapamycin.

Allelic loss of the autophagy gene, beclin 1/BECN1, increases the risk of patients developing aggressive, including human epidermal growth factor receptor 2 (HER2)-positive, breast cancers; however, it is not known whether autophagy induction may be beneficial in preventing HER2-positive breast tumor growth. We explored the regulation of autophagy in breast cancer cells by HER2 in vitro and the effects of genetic and pharmacological strategies to increase autophagy on HER2-driven breast cancer growth in vivo. Our findings demonstrate that HER2 interacts with Beclin 1 in breast cancer cells and inhibits autophagy. Mice with increased basal autophagy due to a genetically engineered mutation in Becn1 are protected from HER2-driven mammary tumorigenesis, and HER2 fails to inhibit autophagy in primary cells derived from these mice. Moreover, treatment of mice with HER2-positive human breast cancer xenografts with the Tat-Beclin 1 autophagy-inducing peptide inhibits tumor growth as effectively as a clinically used HER2 tyrosine kinase inhibitor (TKI). This inhibition of tumor growth is associated with a robust induction of autophagy, a disruption of HER2/Beclin 1 binding, and a transcriptional signature in the tumors distinct from that observed with HER2 TKI treatment. Taken together, these findings indicate that the HER2-mediated inhibition of Beclin 1 and autophagy likely contributes to HER2-mediated tumorigenesis and that strategies to block HER2/Beclin 1 binding and/or increase autophagy may represent a new therapeutic approach for HER2-positive breast cancers.