Elsevier

Gene

Volume 737, 5 May 2020, 144445
Gene

Research paper
Low expression of IL-37 protein is correlated with high Oct4 protein expression in hepatocellular carcinoma

https://doi.org/10.1016/j.gene.2020.144445Get rights and content

Highlights

  • IL-37 expression in cancer tissues was related to serum AFP and liver cirrhosis.

  • IL-37 expression in paracancerous but not cancer tissues was related to tumor size.

  • IL-37 expression was correlated with Oct4 in cancer but not paracancerous tissues.

  • IL-37 expression down regulated Oct4 protein expression in cancer cell lines.

Abstract

Objective

The function of IL-37 in cancer remains largely unclear. The present research was to probe the protein expression of IL-37 and Oct4 in hepatocellular carcinoma (HCC), para-cancerous tissues (PT) and cancer cell lines, and discuss their relationship.

Methods

Forty-nine HCC specimens and forty-nine PT samples were collected for immunohistochemical staining of IL-37 and Oct4 protein. Then, the correlations among IL-37, Oct4 and the clinical indicators were analyzed. In further in vitro studies, IL-37 was over expressed in HepG2 and MHCC97H cancer cell lines by gene transfection using a lipo3000 kit. Finally, the protein expression of IL-37 and Oct4 was detected by immunofluorescence and western blot to verify the in vivo correlation between IL and 37 and Oct4.

Results

In HCC, IL-37 protein expression was weakly positive with a positive rate of 12.2% while Oct4 expression was strongly positive with a positive rate of 91.8%. In PT, strong positive IL-37 (83.7%) and weakly positive Oct4 (91.8%) were shown. The increased IL-37 and decreased Oct4 induced by IL-37 gene transfection were observed through IF in cells. In terms of clinical significance, the difference of IL-37 expression between HCC and PT was statistically significant (χ2 = 51.815, P = 3.2796 × 10−11). IL-37 in tumor tissues was associated with serum AFP (χ2 = 5.515, P = 0.048) and cirrhosis (χ2 = 7.451, P = 0.014). IL-37 expression of PT was link to gender (χ2 = 10.376, P = 0.013) and tumor size (χ2 = 8.118, P = 0.04). The expression of Oct4 in HCC was related to the patient's gender and cirrhosis. Importantly, there was a negative correlation between IL and 37 and Oct4 in tumor tissues (r = -0.299, P = 0.047) but not in PT (P > 0.05). Oct4 protein expression was down-regulated by IL-37 by 63.35% in HepG2 cells (P < 0.05) and 95.20% in MHCC97H cells (P < 0.05).

Conclusion

IL-37 expression in tumor tissues and PT was related to serum AFP and liver cirrhosis, tumor size, respectively. IL-37 protein expression was correlated with Oct4 in cancer cell lines and tumor tissues but not PT. The present study indicated that IL-37 might play a role in the development of HCC.

Introduction

Hepatocellular carcinoma (HCC) is one of the most recurring malignancies worldwide (Bray et al., 2018) and also the second most frequent cause of cancer death rate in China (Chen et al., 2018). And it was closely related to liver injury and inflammation caused by hepatitis virus infection (Van Hees et al., 2016, Kim et al., 2018), long-term alcoholism (Omata et al., 2017) or other issues (Bodzin and Busuttil, 2015). In the inflammatory process of the occurrence and development of liver cancer, a variety of inflammatory-related molecules, such as IL-6 (Chang et al., 2015, Wang et al., 2016), IL-17 (Xu et al., 2018) and IL-24 (Li et al., 2010), play a role. Certain research has stated that the high expression of IL-6 might betoken the adverse prognosis of HCC (Jang et al., 2012). IL-6 can stimulate the expression of STAT3/Oct4 (Chang et al., 2015) and promote the progression of liver cancer. Pro-inflammatory molecules such as IL-22 (Khosravi et al., 2016) and TGF- β (Au et al., 2015, Yu et al., 2017, Rao et al., 2017) can also regulate Oct4 expression, which in turn leads to the malignant changes. Since inflammatory factors play a promotion role in liver cancer by up-regulation of Oct4, then, anti-inflammatory cytokines are likely to inhibit the development of hepatocellular carcinoma by inhibiting Oct4.

The lately named cytokine interleukin 37 (IL-37) with a strong anti-inflammatory function is positioned on chromosome 2. It contains six exons and encodes a 26 KD proteide. IL-37 took effects in anti-inflammatory and immunomodulatory by restraining various inflammatory mediators including IL-1β, IL-6 and TNF-α (Nold et al., 2010). In the liver, IL-37 can suppress the inflammation of hepatocytes and non-parenchymal cells (Sakai et al., 2012). In view of the role of inflammation in tumor progression, IL-37 is likely to act as a tumor inhibitor. A few researches have stated that IL-37 restrained the proliferation of tumor cells in non-small cell lung cancer (Jiang et al., 2018), colon cancer (Günaltay et al., 2017), liver cancer (Zhao et al., 2014, Liu et al., 2016), cervical cancer (Wang et al., 2015), etc. More evidence should be collected to ultimately determine the role of IL-37 in tumors, as the function of IL-37 may be tumor type/context-dependent.

We have antecedently discovered that IL-37 can inhibit cell proliferation and invasion by inhibiting STAT3 pathway (Wang et al., 2015), and induce the cell apoptosis by Bim up-regulation in cervical cancer (Ouyang et al., 2019). The present study focused on the role of IL-37 in HCC. IL-37 could restrain the pro-inflammatory cytokines in diseases has been demonstrated. The pro-inflammatory cytokines mentioned above, however, up-regulated the expression of Oct4 in liver diseases, thereby promoting HCC carcinogenesis. These clues indicated a possible correlation between IL and 37 and Oct4 expression in HCC. Our research analyzed the protein expression of Oct4 and IL-37 in HCC, para-cancerous tissues (PT) and cancer cell lines, and discussed the correlation and clinical significance.

Section snippets

Tissue source

Hepatocellular carcinoma (HCC) and corresponding para-cancerous tissues were obtained from 49 paraffin specimens confirmed by surgical resection in the Department of Pathology of the Foshan First People’s Hospital of Guangdong province (Review number: L[2016]3rd.). Among 49 cases of hepatocellular carcinoma, 38 were male and 11 were female, whose ages were ranged from 18 to 69 years old and the median age was 48 years old. The degrees of differentiation in HCC tissue were high differentiation

Expression of IL-37 and Oct4 protein in cancer tissues and PT

The results of immunohistochemistry showed that IL-37 protein was mainly expressed in cytoplasm (Fig. 1), of which the positive rates in HCC and PT were 12.2% and 83.7%, respectively, and the positive rates of IL-37 protein in HCC and PT was statistically significant (χ2 = 51.815, P = 3.2796 × 10−11, Table 1). These results suggested that IL-37 protein showed a higher positive rate and stronger positive degree in PT, compared with that of HCC.

Oct4 protein expression was found in the nucleus and

Discussion

IL-37 seems to serve a different role in HCC and para-cancerous tissues. For one thing, IL-37 expression of HCC but not para-cancerous tissues were correlated with serum AFP. The elevated serum AFP predicted the carcinogenesis of hepatocellular cells and the progression of HCC (Bodzin and Busuttil, 2015, Van Hees et al., 2016, Kim et al., 2018). Normal hepatic cells express very low-level AFP. The correlation between IL and 37 of HCC and serum AFP indicated that inhibition of IL-37 expression

CRediT authorship contribution statement

Hongsheng Guo: Data curation, Investigation, Writing - original draft. Peng Li: Data curation, Investigation, Software, Writing - original draft. Liudan Su: Data curation, Investigation, Writing - original draft. Kun Wu: Methodology. Kai Huang: Methodology. Ruizhi Lai: Methodology. Jing Xu: Methodology. Dingbao Sun: Methodology. Shuxian Li: Methodology. Ziliang Deng: Methodology. Yan Wang: Methodology. Haina Guo: Methodology. Zhangquan Chen: Methodology. Sen Wang: Conceptualization, Writing -

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This study was funded by the science and technology plan project of Guangdong Province (2016A020215147), by Natural Science Foundation of Guangdong Province, China (2018A030307026), by Medical Science and Technology Research Fund of Guangdong province (A2018380, A2018548) , by scientific planning program of Dongguan (20185071521341, 20185071521328, 201750715016009), by Science Research Fund of Guangdong Medical University (M2017029), by Research Topics of Step-size Pharmaceutical Products on

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    These authors contribute equally to this work and are co-first authors.

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