TRAIL DR5-CTSB crosstalk participates in breast cancer autophagy initiated by SAHA

Han Han,Weiqiang Zhou,Jing Li,Hui Zhou,Dan Zou,Xiuyan Feng

doi:10.1038/cddiscovery.2017.52

Abstract

To investigate the ability of SAHA-induced TRAIL DR5-CTSB crosstalk to initiate the breast cancer autophagy, RTCA assay was performed to assess the effect of SAHA on breast cancer cells, and western blot and ELISA were used to verify the inductive effects on expression of CTSB. Breast cancer cells were transfected with TRAIL DR5 siRNA to block the function of TRAIL DR5. Cell viability and apoptosis of breast cancer cells were analyzed using a muse cell analyzer. The distribution of LC3-II in TRAIL DR5-silenced breast cancer cells treated with SAHA was observed by immunofluorescence microscopy, the mRNA levels of autophagy-related genes were detected by RNA microarray, and the activity of autophagy-related signaling pathways was screened by MAPK antibody array. Results indicated that SAHA did indeed repress the growth of breast cancer cell lines with inducing CTSB expression. Western blot and ELISA results indicated that TRAIL DR5 was involved in the expression of CTSB in SAHA-induced breast cancer cells. Cell viability and apoptosis assays showed that the inactivation of TRAIL DR5 can significantly inhibit the effects of SAHA. An immunofluorescence assay indicated that, with SAHA treatment, MDA-MB-231 and MCF-7 cells underwent apparent morphological changes. While SAHA was added in the TRAIL-DR5 blocked cells, the distribution of LC3-II signal was dispersed, the intensity of fluorescence signal was weaker than that of SAHA alone. RNA array indicated that SAHA significantly increased mRNA expression of autophagy marker LC3A/B whereas the change was significantly reversed in TRAIL DR5-silenced cells. The results of MAPK antibody array showed that SAHA and TRAIL DR5 could affect the activity of AKT1, AKT2, and TOR protein in breast cancer cells. These results provide more evidence that SAHA may stimulate TRAIL DR5-CTSB crosstalk, influence the activity of downstream TOR signalling pathway mainly through the AKTs pathway, and initiate the autophagy of breast cancer cells.

Highlights

Breast cancer has a serious impact on women’s health and it can be life-threatening
In MCF-7 cells, the ratios of live cells went from laboratory studies and clinical applications have exposed 56.96 to 70.89% (Figures 3a and d). These results indicate that the some shortcomings, such as its excessive toxicity at high doses, inactivation of TRAIL DR5 can significantly inhibit the effect of tendency to metabolize, short in vivo half-life, and susceptibility to SAHA on breast cancer cells
The results showed that, it did not show a dose-dependent response, 5 μM SAHA got the optimal inhibitory effect with minimal toxicity in MDA-MB-231 cells, and 10 μM SAHA in MCF-7 cells (Figures 1a and b)

Summary

Introduction

Breast cancer has a serious impact on women’s health and it can be life-threatening. Recent data show that the United States is projected to see 1.69 million new cancer patients and nearly 600 000 deaths in 2017, of which 253 500 new cases will be breast cancer in women. The incidence of breast cancer has become the highest of any type of cancer, and its mortality rate is about to reach second in women.[1]. Despite the lack of clear understanding of its pathogenesis, breast cancer is known to be a hormone-dependent carcinoma in which carcinogenesis is closely associated with the abnormality of related oncogenes and anti-oncogenes.[2] In recent years, the well-researched development of epigenetics has shown that suberoylanilide hydroxamic acid (SAHA, vorinostat), a histone deacetylase inhibitor (HDACi), has strong anti-tumor activity. It can bind to the specific lysine residues in core histone N-terminal and remove the hydrophobic acetyl groups, thereby inhibiting the transcription of some of the genes responsible for cell proliferation, differentiation, and apoptosis.[3,4] Because of its good effects in the pre-clinical observations, SAHA has broad prospects for application

Methods

Results

Conclusion