Gongsheng Yuan
| Gongsheng Yuan |
Gongsheng Yuan, Shuying Yang
Basic and Translational Sciences, University of Pennsylvania, School of Dental Medicine
Introduction
Regulator of G protein signaling 12 (RGS12) is a newly characterized cancer repressor and its expression decreases in oral cancer compared to normal tissue. The aim of this study is to investigate the role of RGS12 in tumor-associated macrophages (TAMs) and to evaluate its potential as a therapeutic target for oral cancer.
Methods
Transcriptome profiling of human oral cancer tissues was analyzed by R script. RGS12 conditional knockout mice in macrophages (RGS12 cKO, LysM-Cre; RGS12fl/fl) were created and subjected to 4NQO induced oral cancer model. The abilities of cell polarization (immunofluorescence), migration (Boyden chamber), and proliferation (WST-1 assay) were evaluated in TAMs. RGS12 interacting proteins in macrophages were analyzed by immunoprecipitation (IP) and Liquid chromatography-mass spectrometry (LC/MS). RGS12 overexpression (OE) and shRNA-mediated knockdown were used to evaluate the primary ciliogenesis, TAMs function, and ubiquitination signaling pathways (immunofluorescence, real-time RT-qPCR, Western blot).
Results
Transcriptome profiling of oral cancer revealed that the RGS12 was significantly decreased in the tissues of oral cancer patients by comparing with normal tissues, which is considered a biomarker and repressor for oral cancer. Mice with RGS12 deficiency in macrophages showed decreased M1 TAMs in oral cancer tissues and extensive proliferation and invasion of oral cancer cells in tongue tissue compared with wild-type mice. Interestingly, the loss of RGS12 decreases the M1 macrophage polarization but promotes the polarization of the M2 macrophages. M1 macrophages increased cilium number and length in comparison with M2 macrophages. Mechanically, RGS12 OE in TAMs increased cilia length and promoted ciliogenesis by inhibiting kinesin family member 2A (KIF2A). The results from LC/MS, immunostaining, and IP analysis showed that RGS12 is associated with MYC binding protein 2 (MYCBP2) to enhance the ubiquitination activity which thereby degraded the KIF2A protein in macrophages. Finally, the overexpression of MYCBP2 in TAMs can fully rescue the shortening cilium and decrease the cilium number caused by the loss of RGS12 and promote the M1 polarization.
Conclusion
We demonstrate that RGS12 is an essential oral cancer biomarker and controller for immunosuppressive TAMs polarization and function.