JOURNAL OF SHANGHAI JIAOTONG UNIVERSITY (MEDICAL SCIENCE) ›› 2021, Vol. 41 ›› Issue (6): 741-748.doi: 10.3969/j.issn.1674-8115.2021.06.006

• Basic research • Previous Articles     Next Articles

Exploratory study on downregulation of PD-L1 in KRAS G12V-mutant non-small cell lung cancer cells by selumetinib

Yun-fang MA1(), Li-na PAN1, Zhen LI1, Bei-li GAO2, Jia-an HU1(), Zhi-hong XU1()   

  1. 1.Department of Geriatrics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
    2.Department of Respiratory and Critical Care, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
  • Online:2021-06-28 Published:2021-06-29
  • Contact: Jia-an HU,Zhi-hong XU E-mail:mayunfang@126.com;jahu_rj@aliyun.com;zhihxu@163.com
  • Supported by:
    Scientific Research Project of Shanghai Municipal Commission of Health and Family Planning(201840083);Weak Discipline Construction Project of Shanghai Municipal Commission of Health and Family Planning(2015ZB0503);Production, Study and Research Project of Shanghai Colleges and Universities(RC20190079)

Abstract: Objective

·To investigate the correlation between Kirsten rat sarcoma viral oncogene(KRAS)-mutant subtypes and programmed cell death ligand 1 (PD-L1) expression in the non-small cell lung cancer (NSCLC) tissues and cell lines, and the possible underlying mechanism.

Methods

·Real-time quantitative PCR and fluorescence-activated cell sorting were used to verify the correlation between PD-L1 mRNA or protein and KRAS mutation status in the NSCLC cell lines. Immunohistochemistry was used to detect the expression of PD-L1 in the tumor tissues of 77 NSCLC patients with early stages (Ⅰa?Ⅱb). The effect of KRAS mutation on the cytokines in the RAS downstream signaling pathway, i.e., protein kinase B (PKB or AKT), mammalian target of rapamycin (mTOR), ribosomal S6 protein kinase (p70S6K), and extracellular regulated protein kinase (ERK), was studied by Western blotting. Dabrafenib (RAF inhibitor), selumetinib [mitogen activated-protein kinase (MEK) inhibitor], GDC0941 (phosphoinositide 3-kinase inhibitor), MK2206 (AKT inhibitor), and rapamycin (mTOR inhibitor) were used to treat 6 KRAS-mutant cell lines, respectively, to detect the regulation of these five tyrosine kinase inhibitors on PD-L1 expression.

Results

·In the NSCLC cell lines, the expressions of PD-L1 mRNA and protein in the KRAS mutant cell lines were significantly higher than those in the KARS wild-type cell lines (P<0.05). KRAS G12V- and G12C-mutant cell lines showed the highest expression of PD-L1 mRNA and protein, respectively. For the NSCLC patients with early stages, the proportions of PD-L1 overexpression in the tumor tissues of the patients with KRAS G12V and G12D mutants were significantly higher than those of the patients with KRAS wild-type. Western blotting showed that in the KRAS-mutated NSCLC cell lines, p70S6K was activated, while ERK, AKT and mTOR were not activated. Moreover, 1 μmol/L GDC0941, 0.5 μmol/L MK2206, and 10 nmol/L rapamycin could not affect the expression of PD-L1 in the 6 KRAS-mutant cell lines. Darafenib (5 nmol/L) up-regulated PD-L1 in only one KRAS G12V-mutant cell line and one L19F-mutant cell line (P<0.05), while selumetinib (0.1 μmol/L ) inhibited the expressions of PD-L1 in three KRAS G12V-mutant cell lines and one L19F-mutant cell line (P<0.05) in a dose-dependent manner.

Conclusion

·The expressions of PD-L1 in the tumor tissues and cell lines of NSCLC with KRAS mutation, especially G12V mutation subtype, were higher than those in the NSCLC tissues and cell lines with KRAS wild-type. Selumetinib can downregulate the expression of PD-L1 in KRAS G12V-mutant NSCLC cells, which suggests that KRAS G12V-mutant NSCLC cells may up-regulate the expression of PD-L1 by upregulating MEK.

Key words: KRAS mutation, non-small cell lung cancer (NSCLC), immunotherapy, programmed cell death ligand 1 (PD-L1), selumetinib

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