Basic Study
Copyright ©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jan 14, 2019; 25(2): 205-219
Published online Jan 14, 2019. doi: 10.3748/wjg.v25.i2.205
Human antigen R mediated post-transcriptional regulation of inhibitors of apoptosis proteins in pancreatic cancer
Ausra Lukosiute-Urboniene, Aldona Jasukaitiene, Giedre Silkuniene, Vidmantas Barauskas, Antanas Gulbinas, Zilvinas Dambrauskas
Ausra Lukosiute-Urboniene, Aldona Jasukaitiene, Giedre Silkuniene, Antanas Gulbinas, Zilvinas Dambrauskas, Institute for Digestive System Research, Lithuanian University of Health Sciences, Kaunas 50161, Lithuania
Ausra Lukosiute-Urboniene, Vidmantas Barauskas, Department of Pediatric Surgery, Lithuanian University of Health Sciences, Kaunas 50161, Lithuania
Antanas Gulbinas, Zilvinas Dambrauskas, Department of Surgery, Lithuanian University of Health Sciences, Kaunas 50161, Lithuania
Author contributions: Lukosiute-Urboniene A carried out the molecular reverse transcription PCR and immunohistological studies, analyzed the data and drafted the manuscript; Jasukaitiene A maintained cell cultures and did the transfection experiments; Silkuniene G performed the western blot analysis, Barauskas V helped to draft the manuscript; Gulbinas A and Dambrauskas Z designed and coordinate the study; All authors read and approved the final manuscript.
Institutional review board statement: Ethical approval was issued by the Ethics Committee of the Lithuanian University of Health Sciences, No. BE-2-10. Consent for the use of surgical tissue specimens for the research purposes was obtained from all the patients or their representatives.
Conflict-of-interest statement: All authors have nothing to disclose.
Data sharing statement: No additional data are available.
ARRIVE guidelines statement: We’ve read the ARRIVE guidelines and prepared the manuscript accordingly.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Ausra Lukosiute-Urboniene, MD, Doctor, Surgeon, Institute for Digestive System Research, Lithuanian University of Health Sciences, Eiveniu Street 4, Kaunas 50161, Lithuania. ausra.urboniene2@lsmuni.lt
Telephone: +370-67-429833 Fax: +370-37-326375
Received: October 18, 2018
Peer-review started: October 18, 2018
First decision: November 1, 2018
Revised: November 6, 2018
Accepted: November 16, 2018
Article in press: November 16, 2018
Published online: January 14, 2019
Processing time: 88 Days and 18.6 Hours
Abstract
AIM

To determine the association of human antigen R (HuR) and inhibitors of apoptosis proteins (IAP1, IAP2) and prognosis in pancreatic cancer.

METHODS

Protein and mRNA expression levels of IAP1, IAP2 and HuR in pancreatic ductal adenocarcinoma (PDAC) were compared with normal pancreatic tissue. The correlations among IAP1/IAP2 and HuR as well as their respective correlations with clinicopathological parameters were analyzed. The Kaplan-Meier method and log-rank tests were used for survival analysis. Immunoprecipitation assay was performed to demonstrate HuR binding to IAP1, IAP2 mRNA. PANC1 cells were transfected with either anti-HuR siRNA or control siRNA for 72 h and quantitative reverse transcription polymerase chain reaction (RT-PCR), western blot analysis was carried out.

RESULTS

RT-PCR analysis revealed that HuR, IAP1, IAP2 mRNA expression were accordingly 3.3-fold, 5.5-fold and 8.4 higher in the PDAC when compared to normal pancreas (P < 0.05). Expression of IAP1 was positively strongly correlated with HuR expression (P < 0.05, r = 0.783). Western blot analysis confirmed RT-PCR results. High IAP1 expression, tumor resection status, T stage, lymph-node metastases, tumor differentiation grade, perineural and lymphatic invasion were identified as significant factors for shorter survival in PDAC patients (P < 0.05). Immunohistological analysis showed that HuR was mainly expressed in the ductal cancer cell’s nucleus and less so in cytoplasm. RNA immunoprecipitation analysis confirmed IAP1 and IAP2 post-transcriptional regulation by HuR protein. Following siHuR transfection, IAP1 mRNA and protein levels were decreased, however IAP2 expression levels were increased.

CONCLUSION

HuR mediated overexpression of IAP1 significantly correlates with poor outcomes and early progression of pancreatic cancer. Further studies are needed to assess the underlying mechanisms.

Keywords: Pancreatic cancer; Inhibitors of apoptosis proteins; Human antigen R; Post-transcriptional regulation

Core tip: We report fundamental knowledge about the direct interaction of RNA stabilizing protein human antigen R (HuR) and inhibitor of apoptosis proteins (IAP1, IAP2). Results suggest that upregulation of IAP1 in pancreatic cancer is significantly related to poor outcomes. Furthermore, HuR plays important role in post-transcriptional regulation of these molecules: HuR protein binds with IAP1, IAP2 and after HuR silencing, IAP1 protein and mRNA expression is downregulated and IAP2 is upregulated. These results demonstrate, that HuR regulates expression of IAP1 and IAP2 in pancreatic cancer cells and that IAP1 may be an important factor facilitating carcinogenic properties of HuR.