Predictive value of KRAS/NRAS, IL-4 VNTR and HPV alterations in metastases of colorectal cancer.

PURPOSE

The main aim of the study was to evaluate the potential roles of KRAS/NRAS proto-oncogenes, IL-4 VNTR variants and HPV prevalence in colorectal cancer metastasis. As the second aim, the interactions of the analyzed genes and viral sequences with both clinicopathological variables and each other were targeted.

METHODS

DNA was extracted using AmoyDx FFPE DNA Extraction kit from paraffin-embedded colorectal tumor tissue samples (n = 60). NRAS/KRAS mutational profiles were determined with real-time polymerase chain reaction using AmoyDx KRAS/NRAS Mutation Detection Kit. Genotyping of IL-4 VNTR was made with PCR. HPV detection was analyzed by PCR with both GP5+/GP6+ consensus primers and type-specific primers for HPV-16 and HPV-18. SPSS v22 (IBM) statistics software was used for all statistical analyses.

RESULTS

From the demographical/clinicopathological parameters, age and biopsy specimens revealed an association with metastasis. KRAS mutation rate was as high as 65 % in the patients and the most prevalent mutation type was G12D. Metastasis risk was 3.19-fold increased in KRAS-mutated patients compared to KRAS-negative ones. IL-4 VNTR genotypes/alleles were not associated with metastasis in our analysis.  The frequency of HPVs in our colorectal cancer cohort was 36.7 %, but HPV positivity was not found to be associated with metastasis.  A significant association was found between HPV and NRAS mutations; NRAS wild-type status acted as a protective factor by 7.5-fold for HPV negativity.

CONCLUSION

Our study comprehensively and concomitantly evaluated several potential molecular risk factors. Future studies designed in such combined approaches will substantially contribute to better manage colorectal cancer tumorigenesis from molecular biological perspective (Tab. 6, Fig. 2, Ref. 40).