Novel insights into the roles and therapeutic implications of MUC1 oncoprotein via regulating proteins and non-coding RNAs in cancer

Mucin 1 (MUC1) is a heterodimeric transmembrane glycoprotein that protects epithelial cells in mammals. The transmembrane C-terminal subunit (MUC1-C) plays a crucial role in oncogenesis. As an oncoprotein, MUC1-C regulates a number of proteins that are associated with tumorigenesis by interacting with oncoproteins, transcription factors, coactivators, etc., inducing proliferation, epithelial-mesenchymal transition (EMT), invasion, stemness, immune evasion, and drug resistance. Moreover, MUC1-C modulates the expression of non-coding RNAs (ncRNAs), which further regulate carcinogenesis by directly binding to specific proteins. ncRNAs can also affect MUC1 protein expression by targeting the MUC1 mRNA 3′ untranslated region (UTR). A series of ncRNAs can modulate cancer development by regulating MUC1-C. This review focuses on the interaction of MUC1-C with proteins and ncRNAs in cancer progression. We also summarize the recent advances in immunotherapy with a focus on therapeutic approaches based on MUC1-C and nanocarrier complexes for cancer treatment.