E3 Ubiquitin Ligase CHIP Inhibits the Interaction between Hsp90β and MAST1 to Repress Radiation Resistance in Non-Small-Cell Lung Cancer Stem Cells

Figure 4

CHIP ubiquitylates MAST1 and suppresses its protein stability. (a) MAST1 expression in the NSCLC-related microarray data GSE74706 (). (b) The correlation between MAST1 and CHIP expression in lung cancer patients of GSE74706 microarray (). (c) The expression of Hsp90β and MAST1 in cancer and adjacent normal tissues of NSCLC patients determined by immunohistochemical staining (). (d) Western blot assay to determine the expression of Hsp90β, MAST1, and CHIP in CD133^- and CD133⁺ A549 cells. (e) The interaction of CHIP, Hsp90β, and MAST1 and the ubiquitination of MAST1 in CD133^- and CD133⁺ A549 cells detected by Co-IP assay. (f) Western blot assay for Hsp90β, MAST1, and CHIP in CD133⁺ A549 cells in response to overexpression of CHIP and Hsp90β alone or in combination. (g) Co-IP assay for interaction of CHIP, Hsp90β, and MAST1 and the ubiquitination of MAST1 in CD133⁺ A549 cells. (h) Western blot assay for MAST1 expression in CD133⁺ A549 cells after treatment with CHX (concentration of 25 μg/mL, an inhibitor of protein synthesis) for 12 h. . Cell experiments were independently repeated three times.

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