The presented work focuses on hypoxia-inducible factor 1a (HIF-1a) and carbonic anhydrase IX (CA IX) in colorectal cancer (CRC). The HIF-1a protein shows increased expression due to hypoxia, resulting in up-regulation of CA IX, which is involved in the survival of hypoxic cancer cells in the tumour microenvironment, with overexpression in various types of carcinomas.

HIF-1a and CA IX immunohistochemical analysis was performed on 111 CRC samples. The primary goal was to determine the correlation of expression of proteins with clinical-morphological parameters and mutual correlation of the proteins in question.

The HIF-1a expression was detected in 72.1% of CRC samples with exclusive nuclear localisation. The immunoreaction intensity was predominantly strong. Carbonic anhydrase IX protein was expressed in 75.7% of cases. The membrane positivity and strong immunoreaction intensity were mainly noticed. No statistically significant correlation between the expression of studied proteins and clinical-morphological parameters was confirmed. However, the results proved a statistically significant correlation in mutual co-localisation of given proteins.

Despite contradictory scientific data, our findings suggest a mutual correlation between HIF-1a and CA IX in CRC. The presented hypothesis that their overexpression may represent a potential new therapeutic target in colorectal carcinogenesis might unveil novel strategies in disease development.