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The role of polymeric immunoglobulin receptor in inflammation-induced tumor metastasis of human hepatocellular carcinoma.

ABSTRACT:

Background

Expression of the polymeric immunoglobulin receptor (pIgR), a transporter of polymeric IgA and IgM, is commonly increased in response to viral or bacterial infections, linking innate and adaptive immunity. Abnormal expression of pIgR in cancer was also observed, but its clinical relevance remains uncertain.

Methods

A human hepatocellular carcinoma (HCC) tissue microarray (n = 254) was used to investigate the association between pIgR expression and early recurrence. An experimental lung metastasis model using severe combined immune-deficient mice was applied to determine the metastatic potential of Madin-Darby canine kidney (n = 5 mice per group) and SMMC-7721 (n = 12 mice per group) cells overexpressing pIgR vs control cells. RNA interference, immunoprecipitation, and immunoblotting were performed to investigate the potential role for pIgR in the induction of epithelial-mesenchymal transition (EMT). In vitro studies (co-immunoprecipitation, immunoblotting, and migration, invasion, and adhesion assays) were used to determine the mechanisms behind pIgR-mediated metastasis. All statistical tests were two-sided.

Results

High expression of pIgR was statistically significantly associated with early recurrence in early-stage HCC and in hepatitis B surface antigen-positive HCC patients (log-rank P = .02). Mice injected with pIgR-overexpressing cells had a statistically significantly higher number of lung metastases compared with respective control cells (Madin-Darby canine kidney cells: pIgR mean = 29.4 metastatic nodules per lung vs control mean = 0.0 metastatic nodules per lung, difference = 29.4 metastatic nodules per lung, 95% confidence interval = 13.0 to 45.8, P = .001; SMMC-7721 cells: pIgR mean = 10.4 metastatic nodules per lung vs control mean = 2.2 metastatic nodules per lung, difference = 8.2 metastatic nodules per lung, 95% confidence interval = 1.0 to 15.5, P = .03). Furthermore, high expression of pIgR was sufficient to induce EMT through activation of Smad signaling.

Conclusions

pIgR plays a role in the induction of EMT. Our results identify pIgR as a potential link between hepatitis B virus-derived hepatitis and HCC metastasis and provide evidence in support of pIgR as a prognostic biomarker for HCC and a potential therapeutic target.

SUBMITTER: Ai J

PROVIDER: S-EPMC3216966 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Background & Aims: Extracellular vesicles (EVs) play a pivotal role in connecting tumor cells and their local and distant microenvironment. Here, we aimed to understand the role and molecular basis of patient-derived EVs in modulating cancer stemness and tumorigenesis in the context of hepatocellular carcinoma (HCC). Methods: EVs were isolated, quantified and characterized from patients’ sera. EVs were tested vigorously, both in vitro and in vivo, by various functional assays. Proteomic analysis was performed to identify the functional components of EVs. The expression level of polymeric immunoglobulin receptor (pIgR) in circulating EVs, tumor and non-tumorous tissues of HCC patients was determined by ELISA, immunoblotting, immunohistochemistry and quantitative PCR. The functional role and underlying mechanism of EVs with an enhanced pIgR expression was elucidated. Blockage of EV-pIgR with neutralizing antibody was performed in nude mice implanted with patient-derived tumor xenograft (PDTX). Results: Circulating EVs of late-stage HCC (L-HCC) patient had significantly elevated pIgR expression when compared to the EVs released by control individuals. The augmenting effect of L-HCC patient in cancer stemness and tumorigenesis was hindered by anti-pIgR antibody. EVs enriched with pIgR consistently promoted cancer stemness and cancerous phenotypes in the recipient cells. Mechanistically, EV-pIgR-induced cancer aggressiveness was abrogated by Akt and β-catenin inhibitors, ascertaining the role of EV-pIgR through the activation of PDK1/Akt/GSK3β/β-catenin signaling axis. Furthermore, anti-pIgR neutralizing antibody attenuated the tumor growth in mice implanted with PDTX. Conclusion: The study illustrates an unrevealed role of EV-pIgR in regulating cancer stemness and aggressiveness, in which EV-pIgR activates PDK1/Akt/GSK3β/β-catenin signaling cascades. The blockage of intercellular communications mediated by EV-pIgR in the tumor microenvironment may provide a new therapeutic strategy for cancer patients.