Arnab Roy Chowdhury, Manoj Pandre, Debabani Roy Chowdhury, Samrat Roy, Sundarajan Kannan, Rajesh Kumar, John Ellingboe, Ajith Kamath and Amit Sharma.
The role of plasticity ratio (PR) in differentiating between metastatic and tumorigenic properties in cell lines and patient tumor samples, Mestastop Solutions Private Limited, Bangalore, India.
Cancer cell plasticity and its role in primary tumorigenesis and secondary metastasis has been the subject of much research, with a particular focus on epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET). We show that many steps in metastasis biology are dependent on the plasticity ratio (PR), the ratio of mesenchymal markers to epithelial markers in a cell line or patient sample. This dependency can be either directly or inversely proportional and PR can be a critical determinant of the progression of metastasis.
To facilitate our understanding of the complex biology of metastasis, we have broken it into 18 steps and recreated each of them in the form of a phenotypic cellular assay. We have characterized PR by measuring mesenchymal and epithelial markers by flow cytometry and then have correlated PR with stemness markers, cell cycle status, and transcription factor expression to understand the correlation of PR to tumorigenesis and invasiveness. Next, we standardized multiple cellular assays starting from basic migration and invasion to complex intravasation, platelet binding, and exosome secretion. We started with colorectal and triple-negative breast cancer cell lines and genetically engineered some of the non-metastatic cell lines (with low PR) into metastatic cell lines (with high PR). We compared them (same cell lines, but different PR) across the assay platform and characterized their differences in terms of metabolism, response to hypoxia and starvation, expression of immunosuppressive markers, and stemness.
We saw that increase in PR was directly proportional to an increase in invasion and intravasation in vitro and metastasis in vivo, but inversely proportional to tumorigenesis in vivo. A nonmetastatic cell line with a lower PR was significantly different in pattern from a pre-metastatic or metastatic cell line, which had a higher PR. Interestingly, genetic manipulation to increase the PR of a non-metastatic cell line resulted in a pattern very similar to the cell lines with higher PR. The change in PR was also responsible for changes in metabolism, apoptosis, autophagy, response to hypoxia, stemness, and immune microenvironment. Early analysis of patient samples also reaffirmed this pattern.
Our data suggest that metastasis is correlated to plasticity ratio, which can be distinguished by our platform and further exploited for anti-metastasis drug discovery and predictive diagnostics.