MiR-21-5p Induces Pyroptosis in Colorectal Cancer via TGFBI.

Rilei Jiang,Haijun Chen,Shaohua Ge,Qin Wang,Xiaolei Chen,Jiang Wu,Yichang Liu,Jiatuo Xu

doi:10.3389/fonc.2020.610545

Abstract

Pyroptosis is a distinct form of programmed cell death in eukaryotic cells that has garnered increasing attention in cancer-related research. Moreover, although miR-21 has been reported as abnormally expressed in colorectal cancer, due to a lack of in-depth research on the transcriptional regulation mechanisms of miR-21, its clinical usage remains limited. Our study is the first, to our knowledge, to compare the clinical manifestations and laboratory phenotypes associated with miR-21-3p and miR-21-5p. Morphologically, the transfection of miR-21-3p or miR-21-5p inhibitors, as well as miR-21-5p mimics into HCT-116 and HT-29 cell lines, induced cell death. Surprisingly, overexpression of miR-21-5p induced cell death more strongly than its knockdown. Mechanistic studies of miR-21-5p overexpression revealed that various inflammatory factors including IL-1β and IL-18 were released, while pyroptosis-associated mRNAs were upregulated and proteins were activated. Moreover, miR-21-5p was found to act as a downstream factor to significantly and directly regulate transforming growth factor beta-induced (TGFB1). Specifically, miR-21-5p overexpression caused downregulation of TGFBI, which may have led to pyroptosis. Collectively, we revealed that miR-21-5p induces pyroptosis in colorectal cancer via TGFBI regulation, thereby providing important mechanistic insights into its antitumor effects and expanding its potential for clinical applications.

Highlights

Colorectal cancer (CRC) was among the most common cancers diagnosed in men and women in 2019 [1]; while the difficulties associated with its early detection, as well as its strong tendency for metastasis, and resistance to conventional therapies [2,3,4] makes its treatment challenging
By using clinical colon tissues from CRC patients’ tumours (n = 5) and adjacent normal tissues (n = 5), we found that the expression of miR-21-3p did not differ significantly between the normal and tumour tissues, while miR-21-5p was more highly expressed in the tumours (Figure 1A)
The expression of miR-21-3p was low in the CRC cell lines while that of miR-21-5p showed a high expression trend in the HT29 and HCT116 cells by PCR (Figure 1B)

Summary

Introduction

Colorectal cancer (CRC) was among the most common cancers diagnosed in men and women in 2019 [1]; while the difficulties associated with its early detection, as well as its strong tendency for metastasis, and resistance to conventional therapies [2,3,4] makes its treatment challenging. In 2015, approximately 376,300 new CRC cases were reported with an estimated 191,000 associated mortalities in China alone [5]. Pyroptosis is recognised as a distinct form of programmed cell death in eukaryotic cells [6], and has recently become a new frontier in cancer-associated research [7]. Pyroptosis is characterised by cell swelling with large bubbles emerging from the plasma membrane [8]. Mature caspase-1 cleaves a protein from the gasdermin family and activates inflammatory cytokines, such as IL-18 and IL-1b7, which recruit inflammatory cells and expand the inflammatory response [9].

Methods

Results

Conclusion