INTRODUCTION
Cancer-associated fibroblasts (CAF) are non-epithelial non-immune cells with mesenchymal properties located in the stroma of the tumor or along its margin.CAFs are described for most solid tumors, including colorectal cancer, as well as their role in tumor progression.
MATERIALS AND METHODS
An immunohistochemical study with 5 antibodies (αSMA, POD, FAP, PDGFRα, PDGFRβ) was performed in 21 cases of colon adenocarcinoma in order to detect CAF in three tumor zones: apical, central and invasive region. Double staining immunohistochemical technology was used — in parallel with each marker a reaction with antibodies to αSMA was performed on one section. The color-separation method in the LAS X program was used to extract and calculate the area of each mark. Statistica 10 software was used for statistical analysis.
RESULTS
The study revealed a higher level of POD expression in the apical part and αSMA in the invasive region. Expression of PDGFRb issignificant andsimilar in all zones. Correlation analysis revealed a strong inverse correlation between the level of αSMA and FAP in the central zone (r=0.79, p=0.034), that indicates different biological roles of FAP and αSMA in the context of CAFs. Also it indicates that these markers are unlikely to reveal the same CAF subpopulations. Two strong trends of direct correlationare detected in the central zone in pairs αSMA/PDGFRa and POD/PDGFRa (p=0.06 and p=0.07, respectively) and a weak trend of direct correlation is found in a pairPDGFRb/PDGFRa (r=0.62, p=0,054). For the first time, differences in the location of markers relative to tumor (epithelial) complexes were revealed: in some cases the closest layer was αSMA, and in some others — POD or FAP. Mixed cases were also noted — the inner layer was represented by two markers at once.
CONCLUSION
The obtained data encourage to pursue more researches of CAF and their features on a larger seriesto increase the understanding of the molecular and biological characteristics of colorectal cancer.
