PAQR4 promotes chemoresistance in non-small cell lung cancer through inhibiting Nrf2 protein degradation
THERANOSTICS
Authors: Xu, Peifang; Jiang, Liping; Yang, Yang; Wu, Mengge; Liu, Baiyang; Shi, Yulin; Shen, Qiushuo; Jiang, Xiulin; He, Yaomei; Cheng, Dating; Xiong, Qiuxia; Yang, Zuozhang; Duan, Lincan; Lin, Jie; Zhao, Song; Shi, Peng; Yang, Cuiping; Chen, Yongbin
Abstract
Purpose: Lung cancer is the leading cause of cancer related deaths worldwide. We have previously identified many differentially expressed genes (DEGs) from large scale pan-cancer dataset using the Cross-Value Association Analysis (CVAA) method. Here we focus on Progestin and AdipoQ Receptor 4 (PAQR4), a member of the progestin and adipoQ receptor (PAQR) family localized in the Golgi apparatus, to determine their clinical role and mechanism in the development of non-small cell lung cancer (NSCLC). Methods: The protein expression profile of PAQR4 was examined by IHC using tissue microarrays, and the effects of PAQR4 on cell proliferation, colony formation and xenograft tumor formation were tested in NSCLC cells. Real-time RT-PCR, co-immunoprecipitation (co-IP) and GST-pulldown assays were used to explore the mechanism of action of PAQR4. Results: We provided evidence showing that PAQR4 is increased in NSCLC cancer cell lines (A549, H1299, H1650, H1975, H358, GLC-82 and SPC-A1), and identified many mutations in PAQR4 in non-small cell lung cancer (NSCLC) tissues. We demonstrated that PAQR4 high expression correlates with a worse clinical outcome, and that its knockdown suppresses cell proliferation by inducing apoptosis. Importantly, overexpressed PAQR4 physically interacts with Nrf2 in NSCLC cells, blocking the interaction between Nrf2 and Keap1. Conclusion: Our results suggest that PAQR4 depletion enhances the sensitivity of cancerous cell to chemotherapy both in vitro and xenograft tumor formation in vivo, by promoting Nrf2 protein degradation through a Keap1-mediated ubiquitination process.
Fabp4-Cre-mediated Sirt6 deletion impairs adipose tissue function and metabolic homeostasis in mice
JOURNAL OF ENDOCRINOLOGY
Authors: Xiong, Xiwen; Zhang, Cuicui; Zhang, Yang; Fan, Rui; Qian, Xinlai; Dong, X. Charlie
Abstract
SIRT6 is a member of sirtuin family of deacetylases involved in diverse processes including genome stability, metabolic homeostasis and anti-inflammation. However, its function in the adipose tissue is not well understood. To examine the metabolic function of SIRT6 in the adipose tissue, we generated two mouse models that are deficient in Sirt6 using the Cre-lox approach. Two commonly used Cre lines that are driven by either the mouse Fabp4 or Adipoq gene promoter were chosen for this study. The Sirt6-knockout mice generated by the Fabp4-Cre line (Sirt6(f/f):Fabp4-Cre) had a significant increase in both body weight and fat mass and exhibited glucose intolerance and insulin resistance as compared with the control wild-type mice. At the molecular levels, the Sirt6(f/f):Fabp4-Cre-knockout mice had increased expression of inflammatory genes including F4/80, TNF alpha, IL-6 and MCP-1 in both white and brown adipose tissues. Moreover, the knockout mice showed decreased expression of the adiponectin gene in the white adipose tissue and UCP1 in the brown adipose tissue, respectively. In contrast, the Sirt6 knockout mice generated by the Adipoq-Cre line (Sirt6(f/f): Adipoq-Cre) only had modest insulin resistance. In conclusion, our data suggest that the function of SIRT6 in the Fabp4-Cre-expressing cells in addition to mature adipocytes plays a critical role in body weight maintenance and metabolic homeostasis.