MAFB is a biomarker for cancer severity and prognosis, and is a potential cancer immunotherapy target

Abstract MAFB is a transcription factor specifically expressed in macrophages. Tumor associated macrophages (TAMs) play a key role in the tumor microenvironment (TME) by inducing immunosuppression, angiogenesis, tumor invasion, and metastasis. However, finding a suitable specific biomarker and target for TAMs is challenging. Our previous study 1 suggested that MAFB could be a suitable marker for tumor-associated macrophages (TAMs) besides MAFB is expressed in anti-inflammatory alternatively activated M2 macrophages in vitro. In the current study, in a cohort of patients with lung adenocarcinoma ( n = 120), increased MAFB expression was related to increased metastasis and poor overall survival rate. Our findings indicate that MAFB can be used as a prognostic marker for assessing metastatic potential in patients with lung adenocarcinoma. Further, we showed that MAFB expression was positively correlated with the expression of CD204 and CD68 in hepatocarcinoma, colon and pancreatic cancers. We demonstrated that MAFB could be used as a biomarker for TAMs and consequently, for assessing severity in various human cancers, including lung, liver, colon, and pancreatic cancers, according to the immunohistochemical analysis of the expression of MAFB, CD68, and CD204. In addition, we showed that MAFB was expressed in TAMs expressing Programmed cell death protein-1 and/or Programmed cell death ligand 1 (TAM PD-1 + and TAM PD-L1 + ) cells in lung adenocarcinoma and Lewis lung carcinoma (LLC) mouse model. These findings indicate that MAFB can be a potential target for drug development against TAM PD-1 + and TAM PD-L1 + cells. In summary, transcriptional factor MAFB can be used as a specific biomarker, prognostic marker, and a potential target for cancer immunotherapy against TAMs.