Survival-associated heterogeneity of marker-defined perivascular cells in colorectal cancer

Abstract

Perivascular cells (PC) were recently implied as regulators of metastasis and immune cell activity. Perivascular heterogeneity in clinical samples, and associations with other tumor features and outcome, remain largely unknown. Here we report a novel method for digital quantitative analyses of vessel characteristics and PC, which was applied to two collections of human metastatic colorectal cancer (mCRC). Initial analyses identified marker-defined subsets of PC, including cells expressing PDGFR-beta or alpha-SMA or both markers. PC subsets were largely independently expressed in a manner unrelated to vessel density and size. Association studies implied specific oncogenic mutations in malignant cells as determinants of PC status. Semi-quantitative and digital-image-analyses-based scoring of the NORDIC-VII cohort identified significant associations between low expression of perivascular PDGFR-alpha and -beta and shorter overall survival. Analyses of the SPCRC cohort confirmed these findings. Perivascular PDGFR-alpha and -beta remained independent factors for survival in multivariate analyses. Overall, our study identified host vasculature and oncogenic status as determinants of tumor perivascular features. Perivascular PDGFR-alpha and -beta were identified as novel independent markers predicting survival in mCRC. The novel methodology should be suitable for similar analyses in other tumor collections.