Prostate cancer (PCa) is one of the main causes of death in men all over the world. To date, the emerging issue is the search for new diagnostic and prognostic biomarkers to distinguish patients with different risk types. Recent studies of PCa biomarkers have drawn attention to the remarkable heterogeneity of this tumor. Tumor heterogeneity (TH) is the main limitation of the ability to use biomarkers’ gene panels in clinics because of different cell subclones within one tumor.
Here we describe the relationship between tumor cells in a model of heterogeneous prostate cancer. Our model was based on direct and indirect co-cultivation of 2 prostate cell lines with aggressive (PC3-GFP) and indolent (22Rv1) phenotypes. To evaluate the tumor aggressiveness, we described the surface phenotype of adhesion molecules, measured the expression of genes related to metastasis in prostate cancer (Ai et al., 2017; Fan et al., 2018) and performed the motility tests.
In experiments with direct co-cultivation of PC3 (aggressive) and 22Rv1 (indolent) cancer cells, we found a decrease of CD29 (integrin beta 1) on PC3 cells within 3 days, while the expression of other surface adhesion molecules (CD54, CD38, CD24 and CD44) was not altered, the surface phenotype of 22Rv1 did not change. Next, we assessed the expression of genes related to metastasis and showed that after 3 days of direct co-cultivation the expression of FLNC, AMACR, SNCG, HPN genes increases at least 2.5 times in 22Rv1, while HPN and FASN are upregulated in PC3 cells (for all measurements p<0.05, Mann-Whitney test). However, during indirect co-cultivation we did not detect the change in expression of metastasis-related genes neither in PC3 nor in 22Rv1. In experiments with a scratch assay, we showed that wound healing rate decreased by 8 times for PC3 and by 6 times for 22Rv1 compared to controls (p<0.05, Mann-Whitney test, n=3).
Thus, we conclude that the induction of an aggressive tumor phenotype is possible during only direct co-cultivation of cells with an indolent and aggressive tumor phenotype and is manifested in an increase in the expression of PCa biomarker genes associated with migration and metastasis, and describe the model of tumor phenotype induction for prostate cancer.
The authors.
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All authors have declared no conflicts of interest.