HNRNPLL, a newly identified colorectal cancer metastasis suppressor, modulates alternative splicing of CD44 during epithelial-mesenchymal transition.

Abstract

OBJECTIVE:

Despite the recent advances in treatment of colon cancer, the prognosis is unfavourable for patients with distant metastases. The aim of this study was to identify targets for prevention and/or therapy of colon cancer metastasis.

DESIGN:

CMT93 cells, a murine rectal cancer cell line with poor metastasising activity, were transduced with lentiviral shRNA library and transplanted into the rectum of syngeneic C57BL/6 mice. Genomic DNA was collected from metastatic lesions, and the integrated shRNA were retrieved by PCR for sequencing, followed by identification of the candidate genes targeted by the shRNA.

RESULTS:

The genome-wide shRNA library screen identified Hnrnpll (heterogeneous nuclear ribonucleoprotein L-like) encoding a pre-mRNA splicing factor as a candidate metastasis suppressor gene. Knockdown of Hnrnpll enhanced matrigel invasion activity of colon cancer cells in vitro, as well as their metastatic ability in vivo. An RNA-immunoprecipitation analysis showed Hnrnpll-binding to Cd44 pre-mRNAs, and the level of Cd44 variable exon 6 (Cd44v6), a poor prognosis marker of colorectal cancer, was increased by knocking down Hnrnpll. A neutralising Cd44v6 antibody suppressed the matrigel invasion ability induced by Hnrnpll knockdown. HNRNPLL expression was downregulated when colon cancer cells were induced to undergo epithelial-mesenchymal transition (EMT). Immunohistochemistry of clinical samples indicated that colorectal cancer cells with low E-cadherin expression at the invasion front exhibited decreased HNRNPLL expression.

CONCLUSIONS:

HNRNPLL is a novel metastasis suppressor of colorectal cancer, and modulates alternative splicing of CD44 during EMT.

• Authors: Keiichiro Sakuma, Eiichi Sasaki, Kenya Kimura, Koji Komori, Yasuhiro Shimizu, Yasushi Yatabe, Masahiro Aoki
• Journal: Gut (Gut) Vol. 67 Issue 6 Pg. 1103-1111 (06 2018) ISSN: 1468-3288 [Electronic] England
• PMID: 28360095 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Chemical References

• CD44v6 antigen
• Heterogeneous-Nuclear Ribonucleoproteins
• Hyaluronan Receptors
• Tumor Suppressor Proteins
• hnRNPLL protein, mouse

Topics

• Alternative Splicing (genetics)
• Animals
• Blotting, Western
• Cell Culture Techniques
• Cell Line, Tumor
• Colorectal Neoplasms (genetics, metabolism, pathology)
• Epithelial-Mesenchymal Transition (genetics)
• Gene Expression Regulation, Neoplastic (genetics)
• Heterogeneous-Nuclear Ribonucleoproteins (metabolism)
• Hyaluronan Receptors (metabolism)
• Immunoprecipitation
• Mice
• Mice, Inbred C57BL
• Mice, Knockout
• Reverse Transcriptase Polymerase Chain Reaction
• Tumor Suppressor Proteins (metabolism)