A novel quantitative method of pten expression assessment in tumor tissue.

Phosphatase and Tensin Homolog deleted on chromosome 10 (PTEN) gene is one of the most important tumor suppressor genes which is involved in the regulation of many signaling cascades (AKT/PKB and MAPK). Subtle changes in its activity lead to cancer susceptibility or aggressive tumor behaviour. Despite the diversity of mechanisms leading to PTEN inactivation, it is frequently associated with a decreased or complete loss of protein expression. About 20% decrease in PTEN expression could lead to the development of cancer. There have been no objective, quantitative methods of PTEN expression assessment that allow to measure the subtle variations of the protein concentration in a tissue-contextual manner. A new quantitative algorithm of immunostaining evaluation based on combination of color deconvolution and relative chromogen signal intensity was used in the study. The proposed algorithm was implemented in the popular ImageJ image analysis software and positively verified in cancer cell lines and tissue models as well as in the tissue samples of colorectal cancer (CRC) patients. The proposed quantitative method of PTEN expression assessment creates an alternative to currently available subjective methods and forms the basis for inter-case and inter-tissue comparisons. Using the algorithm it would be possible to identify three groups of patients with advanced colorectal cancer which could significantly differ in the overall survival. The research should be continued.

Does human papilloma virus participate in colorectal carcinogenesis?

Colorectal cancer is one of the most commonly diagnosed neoplasms still associated with relatively high mortality. Viral infections are often mentioned among the neoplasm transformation risk factors. Incidence of human papilloma virus (HPV), associated with high oncogenic risk, in the large intestine and the meaning of its presence in the colorectal carcinogenesis are still not clear. The aim of the study was to show a presence of HPV in specimens of adenomatous polyps and colorectal cancer using the Q-PCR method. Fifty patients (32 M/18W, mean age 62.8 years) were enrolled in the study, for whom tissue samples were obtained. Study material involved paraffin blocks derived from samples collected by flexible sigmoidoscopy from 10 polyps and 10 large intestine adenocarcinomas and 30 paraffin blocks with specimens of surgically removed large intestine adenocarcinomas. Presence of HPV genome was confirmed by quantitative PCR method using commercially available Abbott RealTime High Risk HPV test. The test is able to detect 14 most prevalent high oncogenic risk subtypes of human papilloma virus. Status of HPV DNA was successfully assessed in all 50 samples. No HPV DNA was discovered in any of the tested samples. Presence of high oncogenic risk HPV subtypes in large intestine adenoma and adenocarcinoma seems to be very rare, and its dominating role in the pathogenesis of colorectal cancer, even if possible, is unlikely.