Cancer Letters

Cancer Letters

Volume 380, Issue 1, 28 September 2016, Pages 98-105
Cancer Letters

Original Articles
The hepatitis B virus X protein promotes pancreatic cancer through modulation of the PI3K/AKT signaling pathway

https://doi.org/10.1016/j.canlet.2016.06.011Get rights and content

Highlights

  • PDAC patients with serum HBsAg+ tended to have lower median survival times.

  • Occult HBV infection might be vital for PDAC oncogenesis and aggravation.

  • HBx could increase the malignance of PDAC by PI3K/AKT and other signaling pathways.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive and lethal cancer, with poor outcomes. Infection with the hepatitis B virus (HBV) may be associated as a worse prognosis for PDAC patients; however, the mechanisms involved in this process are unclear. We evaluated whether HBV infection leads to PDAC with a more aggressive phenotype, and attempted to elucidate the mechanisms involved. Clinicopathological data and outcomes from 64 patients with PDAC were collected and compared between serum HBsAg+ and HBsAg− patients. Furthermore, we examined the effects of the HBV X protein (HBx) on proliferation and migration of the pancreatic cancer cell lines PANC-1 and SW1990. We investigated expression changes of over 500 proteins by protein array analysis and identified several HBV- and PDAC-related candidates, which were further validated by immunoblotting and enzyme-linked immunosorbent assay. No differences in clinicopathological features were observed between HBsAg+ and HBsAg− patients; however, HBsAg+ patients had a shorter median survival time (8 vs. 13 months), although the differences were not significant. HBV DNA was detected in clinical specimens, even in PDAC patients considered “HBV-free”, potentially due to occult infection. HBx expression significantly enhanced cellular proliferation and migration and induced an epithelial-mesenchymal transition phenotype. Expression of ErbB4 and TGF-α was increased in parallel with HBx expression, and several downstream pathways including PI3K/AKT, MAPK, and ERK were upregulated. Inhibition of the PI3K/AKT pathway reversed the effects of HBx in PDAC cell lines. HBx may, therefore, contribute to the progression of PDAC through modulation of these pathways.

Introduction

Pancreatic ductal adenocarcinoma (PDAC) is the cancer with the worst prognosis. Recent advances in diagnostics and therapy have failed to satisfactorily improve the overall survival (OS) of this lethal disease, with a 5-year OS of only 8%, even in the US [1]. Several risk factors have been identified for pancreatic cancer, including cigarette smoking, diabetes mellitus, obesity, heavy alcohol use, and pancreatitis [2].

Viral infection is a common risk factor for multiple types of cancer. It has been estimated that chronic viral infection contributes to 15–20% of cancers, such as hepatitis B virus (HBV)- and hepatitis C virus-related liver cancers, human papilloma virus-related cervical cancer, Epstein–Barr virus-related Burkitt lymphoma and nasopharynx cancer, and human immunodeficiency virus-related Kaposi's sarcoma and non-Hodgkin's lymphoma [3]. Complicated mechanisms including the induction of inflammation and genome disturbance are involved in virus-associated cancers [4], [5]. The role of viral infection in pancreatic cancer has also been explored [6], [7], [8], [9]. Recently, there have been an increasing number of epidemiological studies on the association between the well-known oncogenic virus, HBV, and PDAC, although the relationship between the two remains unclear. The majority of these studies determined that HBV infection was an independent risk factor and prognostic factor for PDAC patients, and suggested a unique subtype of PDAC with a worse prognosis [3], [8], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19]. However, other studies found no association between HBV infection and PDAC [20], [21], [22], [23], [24]. HBV is a liver-tropic virus, but previous studies have demonstrated its capacity to invade extra-hepatic organs including the pancreas [25], [26], [27]. While the biological significance of this phenomenon is under debate, Lang and colleagues proposed that the harboring of HBV in extra-hepatic tissues serves as an extra-hepatic source of virus without the pathological consequences on the infected extra-hepatic organs [26]. Yoshimura and colleagues, however, found that HBV DNA, HBV surface antigen (HBsAg), replication intermediates and antibodies could be detected in the pancreatic fluid and pancreatic tissue of chronic pancreatitis or PDAC patients with HBV infection [27], suggesting that HBV could replicate in pancreatic cells. In addition, this result also implied that HBV infection in the pancreas is a chronic process and that the pancreas is capable of accommodating HBV replication. This could result in pancreatic damage and provide a mechanism through which HBV infection could result in a worse prognosis for PDAC patients. Given the same origin (endodermal pluripotent stem cells) of the liver and pancreas during the early stages of embryogenesis, it is possible that the two organs share multiple genetic traits and may have similar responses to HBV. Furthermore, previous studies have shown that HBV infection increased the rate of synchronous liver metastasis and was an independent prognostic factor in PDAC [14]. Together these studies indicate that HBV infection could be an aggravating factor for PDAC.

The relation between HBV and liver cancer has been extensively studied. The hepatitis B virus X protein (HBx), a small 17-kDa soluble protein encoded by the HBV X gene, is essential for HBV-related oncogenesis in the liver [28], [29]. Previous studies on hepatic cancer showed that HBx was a general trans-activator and played a significant role in intracellular signal transduction, viral replication, cell cycle progression, cellular proliferation and apoptosis, protein degradation and the genetic stability of liver cells [28], [30], [31]. In this study, we evaluated HBV as a potential aggravating factor for PDAC and identified the mechanisms through which HBx could influence PDAC progression.

Section snippets

Clinical data collection

Samples from sixty-four patients with PDAC confirmed by pathology were collected between 2013 and 2014 at the Second Affiliated Hospital, Zhejiang University School of Medicine. Two patients died of other diseases following surgery and were excluded from the survival analysis. Six patients were lost to follow-up. The demographic, clinical, pathological data and outcomes were collected under the supervision of the institutional ethics committee. HBV infection was evaluated by serum HBsAg,

PDAC patients with serum HBsAg+ appear to show a worse prognosis

No differences are observed with regards to T stage, vascular invasion, lymph node metastasis, and peri-neural invasion between PDAC patients with serum HBsAg− or HBsAg+. Overall survival (OS) is shorter in patients with serum HBsAg+ (median survival time, 8 vs. 13 months, P = 0.310, Fig. 1A). Since overall survival can be affected by postoperative treatments, such as chemotherapy, stratification analysis, according to the frequency of chemotherapy (<12 times, and ≥12 times), was applied to

Discussion

Although several epidemiological studies have suggested a link between HBV and pancreatic cancer, the extent of this relationship is still unknown. HBV infection is a complex process that is incompletely understood. HBV infection can be latent and the virus can exert effects prior to detection. Occult HBV infection is characterized by negative serum HBsAg but positive serum HBV DNA or tissue HBV DNA [37]. Epidemiological studies of HBV infection in China showed that, in patients with occult HBV

Authors' contributions

Tingbo Liang, Xueli Bai and Qi Zhang conceived the idea. Yiwen Chen, Xueli Bai, Liang Wen, Wei Su, Qihan Fu, Xu Sun, Yu Lou, Jiaqi Yang, Jingying Zhang, Qi Chen, and Jianxin Wang performed the experiments. Yiwen Chen and Qi Zhang analyzed the data and wrote the manuscript. All authors approved the manuscript.

Conflict of interest

None.

Acknowledgments

This work was financially supported by the National High Technology Research and Development Program of China (SS2015AA020405), the Training Program of the Major Research Plan of the National Natural Science Foundation of China (91442115), the Key Innovative Team for the Diagnosis and Treatment of Pancreatic Cancer of Zhejiang Province (2013TD06), the National Natural Science Foundation of China (81401954), the Zhejiang Provincial Natural Science Foundation (LY14H160034 and LY13H160012), and

References (43)

  • G. Trikudanathan et al.

    Association between Helicobacter pylori infection and pancreatic cancer. A cumulative meta-analysis

    JOP

    (2011)
  • M. Xiao et al.

    Association between Helicobacter pylori infection and pancreatic cancer development: a meta-analysis

    PLoS ONE

    (2013)
  • J.H. Xu et al.

    Hepatitis B or C viral infection and risk of pancreatic cancer: a meta-analysis of observational studies

    World J. Gastroenterol

    (2013)
  • S. Fiorino et al.

    HBV- and HCV-related infections and risk of pancreatic cancer

    JOP

    (2013)
  • Y. Wang et al.

    Hepatitis B virus status and the risk of pancreatic cancer: a meta-analysis

    Eur. J. Cancer Prev

    (2013)
  • G. Luo et al.

    HBV infection increases the risk of pancreatic cancer: a meta-analysis

    Cancer Causes Control

    (2013)
  • M.M. Hassan et al.

    Association between hepatitis B virus and pancreatic cancer

    J. Clin. Oncol

    (2008)
  • D.S. Wang et al.

    Are risk factors associated with outcomes in pancreatic cancer?

    PLoS ONE

    (2012)
  • X.L. Wei et al.

    The status of HBV infection influences metastatic pattern and survival in Chinese patients with pancreatic cancer

    J. Transl. Med

    (2013)
  • Q. Ben et al.

    Hepatitis B virus status and risk of pancreatic ductal adenocarcinoma: a case-control study from China

    Pancreas

    (2012)
  • D.S. Wang et al.

    ABO blood group, hepatitis B viral infection and risk of pancreatic cancer

    Int. J. Cancer

    (2012)
  • Cited by (43)

    • Bidirectional and dynamic interaction between the microbiota and therapeutic resistance in pancreatic cancer

      2021, Biochimica et Biophysica Acta - Reviews on Cancer
      Citation Excerpt :

      For example, an intratumoral bacterial signature (Pseudoxanthomonas-Streptomyces-Saccharopoly-spora-Bacillus clausii) positively predicted long-term survival in PDAC patients, while Fusobacterium species enriched in tumor indicated a poor prognosis [33,34]. A few studies have hinted that H. pylori and some viruses (such as hepatitis B virus [HBV] and hepatitis C virus [HCV]), may be potential risk factors for PDAC, but reliable evidence is still lacking [35–39]. Apart from the intratumoral microbiota, the oral microbiota also plays a vital role in the development of PDAC.

    • The role of viruses in adenocarcinoma development

      2020, Infection, Genetics and Evolution
      Citation Excerpt :

      These activities play an important role in the progression of pancreatic cancer (Chen et al., 2016b). HBx may causes cell migration and metastasis by means of increasing cellular matrix degradation and decreasing in cell adhesioreatic cancer (Zhang et al., 2012; Chen et al., 2016b). It has also been observed, that HBx increases the expression of ErbB4 and TGF-α.

    • Microbiome of Pancreatic Cancer: Involvement in Cancer Development and Chemo-/ Immunotherapy

      2023, The Pancreas: an Integrated Textbook of Basic Science, Medicine, and Surgery, Fourth Edition
    View all citing articles on Scopus

    Yiwen Chen and Xueli Bai contributed equally to this work.

    View full text