RESUMO
The Dickkopf family proteins (DKKs) are strong Wnt signaling antagonists that play a significant role in colorectal cancer (CRC) development and progression. Recent work has shown that DKKs, mainly DKK1, are associated with the induction of chemoresistance in CRC and that DKK1 expression in cancer cells correlates with that of protein arginine N-methyltransferase 5 (PRMT5). This points to the presence of a regulatory loop between DKK1 and PRMT5. Herein, we addressed the question of whether PRMT5 contributes to DKK1 expression in CRC and hence CRC chemoresistance. Both in silico and in vitro approaches were used to explore the relationship between PRMT5 and different DKK members. Our data demonstrated that DKK1 expression is significantly upregulated in CRC clinical samples, KRAS-mutated CRC in particular and that the levels of DKK1 positively correlate with PRMT5 activation. Chromatin immunoprecipitation (ChIP) data indicated a possible epigenetic role of PRMT5 in regulating DKK1, possibly through the symmetric dimethylation of H3R8. Knockdown of DKK1 or treatment with the PRMT5 inhibitor CMP5 in combination with doxorubicin yielded a synergistic anti-tumor effect in KRAS mutant, but not KRAS wild-type, CRC cells. These findings suggest that PRMT5 regulates DKK1 expression in CRC and that inhibition of PRMT5 modulates DKK1 expression in such a way that reduces CRC cell growth.
Assuntos
Neoplasias Colorretais , Peptídeos e Proteínas de Sinalização Intercelular , Proteína-Arginina N-Metiltransferases , Humanos , Proteína-Arginina N-Metiltransferases/metabolismo , Proteína-Arginina N-Metiltransferases/genética , Proteína-Arginina N-Metiltransferases/antagonistas & inibidores , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/genética , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Doxorrubicina/farmacologia , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Proteínas Proto-Oncogênicas p21(ras)/genética , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacosRESUMO
Protein arginine N-methyltransferase 5 (PRMT5) enzyme is one of the eight canonical PRMTs, classified as a type II PRMT, induces arginine monomethylation and symmetric dimethylation. PRMT5 is known to be overexpressed in multiple cancer types, including colorectal cancer (CRC), where its overexpression is associated with poor survival. Recent studies have shown that upregulation of PRMT5 induces tumor growth and metastasis in CRC. Moreover, various novel PRMT5 inhibitors tested on CRC cell lines showed promising anticancer effects. Also, it was suggested that PRMT5 could be a valid biomarker for CRC diagnosis and prognosis. Hence, a deeper understanding of PRMT5-mediated CRC carcinogenesis could provide new avenues towards developing a targeted therapy. In this study, we started with in silico analysis correlating PRMT5 expression in CRC patients as a prelude to further our investigation of its role in CRC. We then carried out a comprehensive review of the scientific literature that dealt with the role(s) of PRMT5 in CRC pathogenesis, diagnosis, and prognosis. Also, we have summarized key findings from in vitro research using various therapeutic agents and strategies directly targeting PRMT5 or disrupting its function. In conclusion, PRMT5 seems to play a significant role in the pathogenesis of CRC; therefore, its prognostic and therapeutic potential merits further investigation.