Suppressor PAQR3 Overexpression Associated With The Clinical Signifcance And Prognosis In Esophageal Squamous Cell Carcinoma Via Inhibition Of ERK Signaling

Objective: Progestin and adipoQ receptor family member 3(PAQR3)has exhibited anticancer activity in multiple malignancies.However,its expression and function in esophageal squamous cell carcinoma(ESCC)is still elusive.PAQR3 is a newly discovered tumor suppressor,its function in esophageal cancer has not been well verified.This study will explore the relationship between PAQR3 and survival and clinical phenotype in patients with esophageal squamous cell carcinoma.Methods: In this work,we examined the expression of PAQR3 in 80 surgically resected ESCC specimens and their adjacent normal tissues.The expression of PAQR3 in ESCC cell lines was measured after treatment with the demethylating agent 5-aza-2'-deoxycytidine(5-Aza-CdR).The effects of overexpression of PAQR3 on cell proliferation,colony formation,invasion,and tumorigenesis were investigated.Results: It was found that the PAQR3 mRNA level was significantly lower in ESCC than that in adjacent normal tissues(P=0.001).Low PAQR3 expression was significantly associated with more advanced T stage(P=0.019)and absent lymph node involvement(P=0.011).Compared to normal esophageal epithelial cells,ESCC cells had significantly lower levels of PAQR3.5-Aza-CdR treatment led to an induction of PAQR3 in ESCC cells.Enforced expression of PAQR3 significantly inhibited ESCC cell proliferation,colony formation and invasion.Moreover,PAQR3 overexpression blocked cell cycle transition from G1 to S phase,which was associated with induction of p27 and p21 and reduction of cyclin D1,CDK4,and CDK2.Mechanistically,overexpression of PAQR3 suppressed the phosphorylation of ERK1/2 in ESCC cells.In vivo tumorigenic studies confirmed that PAQR3 overexpression retarded the growth of ECA-109 xenograft tumors and inhibited the activation of ERK signaling.Conclusions: Taken together,PAQR3 is epigenetically silenced in ESCC and restoration of PAQR3 suppresses the aggressive phenotype of ESCC cells.Therefore,PAQR3 may represent a potential target for the treatment of ESCC.