Abstract
BackgroundHepatocellular carcinoma (HCC) is one of the most fatal malignancies worldwide, and CD133 is a popular cancer stem cell (CSC) marker for HCC. CD133+ CSCs have been reported to resist conventional chemo- and radiotherapy, but little is known about their response to immune surveillance. Interferon-gamma (IFN-γ) is one of key cytokines that the immune system produce to eradicate cancer cells, so we investigated the function of IFN-γ on CD133+ HCC CSCs in this study.MethodsThe response of CD133+ cells to IFN-γ was performed with functional assays (cell proliferation assay and tumor formation in nude mice), flow cytometry, immunofluorescence staining and RNA interference.ResultsWe found that IFN-γ inhibited the proliferation of cell lines with low percentage of CD133+ cells (wild-type human cells, BEL7402, QGY7701) but it did not affect the proliferation of cell lines with high percentage of CD133+ cells (wild-type human cells, Huh7, PLC8024) in vivo and in vitro (nude mice). Flow cytometry analysis demonstrated that the percentage of CD133+ cells increased after IFN-γ treatment of low CD133+ cell lines. Furthermore, IFN-γ induced the autophagy of low CD133+ cell lines to decrease proliferation.ConclusionCD133+ HCC CSCs resisted IFN-γ-induced autophagy, which might also be a mechanism through which CSCs resist immune eradication.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-016-2050-6) contains supplementary material, which is available to authorized users.
Highlights
Hepatocellular carcinoma (HCC) is one of the most fatal malignancies worldwide, and CD133 is a popular cancer stem cell (CSC) marker for HCC
CD133+ cells were detected in mice eight weeks after HCC cell injection To study whether cancer cells can live for long periods of time in nude mice, 1×104 PLC8024 cells were subcutaneously injected into nude mice
Results showed that a subset of tumor cells were CD133+ (Fig. 1), indicating that CSCs could live for long periods of time in tested animals
Summary
Hepatocellular carcinoma (HCC) is one of the most fatal malignancies worldwide, and CD133 is a popular cancer stem cell (CSC) marker for HCC. CD133+ CSCs have been reported to resist conventional chemo- and radiotherapy, but little is known about their response to immune surveillance. Interferon-gamma (IFN-γ) is one of key cytokines that the immune system produce to eradicate cancer cells, so we investigated the function of IFN-γ on CD133+ HCC CSCs in this study. Because it is incurable, cancer is one of the most fatal diseases, and it affects millions of people worldwide [1].
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