Pilot study on quantifying the epithelial/mesenchymal hybrid state in the non-muscle invasive and muscle invasive bladder tumors: A promising marker of diagnosis and prognosis

Background

Manifestation of epithelial-to-mesenchymal transition (EMT) program in tumor cells is associated with the occurrence of multiple intermediate phenotypic states namely epithelial (E), mesenchymal (M) and hybrid E/M across the epithelial-mesenchymal spectrum and these states exhibit different invasive properties. Understanding the cellular and molecular mechanisms defining the E/M hybrid state of the cells during bladder tumor development may significantly aid in the identification of novel diagnostic and prognostic markers.

Materials and methods

The present study is taken up to identify hybrid E/M score based on the immunohistochemical localization and surface expressions of epithelial proteins [E-cadherin and Beta-catenin] and mesenchymal marker proteins [N-cadherin and Vimentin] on formalin fixed paraffin embedded tumor sections of the prospective series of 99 non-muscle invasive bladder cancer (NMIBC) and 87 muscle invasive bladder cancer (MIBC) patients. E/M score was then statistically examined with patients’ demographics to assess its potential in the diagnosis and prognosis of UCB patients.

Results

Among the E (E-cadherin^high, β-catenin^high), hybrid E/M (E-cadherin^low, β-catenin^low, N- cadherin^high and Vimentin^high) and M (N-cadherin^high and Vimentin^high) phenotypes, E/M phenotype was observed to be more prevalent in MIBC compared to E phenotype in NMIBC subtype. The current study reports the statistical association of tumor stage and tumor grade with the hybrid E/M state of urothelial tumor cells across both the subtypes. Hybrid E/M phenotype in MIBC patients was significantly shown to lower the overall survival time period compared to NMIBC patients. This supports the contribution of hybrid E/M state of tumor cells to the.

aggressiveness of the disease.

Conclusions

Characterizing the hybrid E/M state instead of all or none phenotype becomes an imperative to understand the dynamics of EMT and MET in the tumor pathophysiology of NMIBC and MIBC subtypes, and could contribute to better patient stratification and therapeutic strategies.