The expression of clock genes cry1 and cry2 in human colorectal cancer and tumor adjacent tissues correlates differently dependent on tumor location.

Colorectal cancer (CRC) exhibits differences in its features depending on the location of the tumor. The role of the circadian system in carcinogenesis is accepted, and many studies report different clock gene expression in tumors compared to healthy tissue. However, little attention is given to the changes in clock genes in tumors arising from various locations across the colon and rectum. The aim of our study was to investigate the expression of the clock genes cry1 and cry2 in human CRC tissue and tissue adjacent to colorectal tumors in a cohort of 64 patients by real time PCR. Expression of cry1 in the entire patient cohort was higher in tumors compared to adjacent tissues in the right-sided colon but not in the left-sided colorectum. Difference in cry1 expression between tumor and adjacent tissue in the right-sided colon was preserved in women and a trend was observed in men. Higher expression of cry1 in the right-sided colon tumor tissue was associated with worse survival in women and the expression of cry1 in the left-sided colorectum was significantly higher in the adjacent tissue compared to tumor in men but not in women. Expression of cry2 was lower in the tumor than in adjacent tissue in both the right and left-sided colorectum. This trend was generally preserved, but the difference reached significance level only in the male left-sided colon, and cry2 expression in the tumor tissue significantly correlated with location of the tumor in men with grade 2 cancer. Finally, we detected significant correlation between tumor location and cry1 expression in the adjacent tissue and the combined results establish that tumor influence on adjacent tissue is dependent on tumor location. Changed clock gene expression should therefore be considered in specific CRC patient sub-groups.

Downregulation of miR-30c-5p expression in colorectal cancer tissue is sex-dependent.

We report that decreased expression of miR-30c in tumor compared to adjacent tissue is sex-dependent in colorectal cancer (CRC) patients. High expression of miR-30c was associated with better survival in the whole cohort. When the cohort was split into male and female subcohorts, decreased miR-30c expression in tumor compared to adjacent tissue was observed only in males. Expression of miR-30c was decreased in CRC tumor tissue in male patients with nodes involvement compared to those without metastases in nodes and this difference was not observe in females. Next dependency of miR-30c expression on oestrogen receptor beta (ERbeta) mRNA levels in tumor was tested. In males with low expression of ERbeta, we observed a significant decrease in miR-30c levels in patients with nodes involvement compared to those without nodes involvement. This difference was not observed in males with high ERbeta mRNA levels and in females. Accordingly, males with low expression of ERbeta and high expression of miR-30c showed a better survival that those with low expression ERbeta and low expression of miR-30c. It is possible to conclude that whole cohort survival dependence on miR-30c is mostly generated by a subcohort of males with low expression of ERbeta mRNA in tumor tissue.

Sex-dependent regulation of estrogen receptor beta in human colorectal cancer tissue and its relationship with clock genes and VEGF-A expression.

The incidence of colorectal cancer (CRC) shows a sex-dependent difference in humans. The aim of this study was to analyze estrogen receptor beta mRNA (ERbeta) expression in patients with CRC with respect to their gender and clinicopathological features. Since cancer progression is accompanied by tumor vascularization, VEGF-A (vascular endothelial growth factor A) transcription was analyzed along with ERbeta mRNA. ERbeta mRNA was also correlated with the expression of clock genes, which are known to influence the cell cycle. ERbeta mRNA expression in females with CRC showed an inverse association with increasing tumor staging that was not observed in males. Lower levels of ERbeta mRNA were observed in females with a higher clinical stage compared with those with earlier-stage tumors. ERbeta mRNA expression showed a significant positive correlation with mRNA of clock genes period 2 and cryptochrome 2 in healthy but not in cancerous tissue in males. Expression of VEGF-A mRNA showed a negative correlation with ERbeta mRNA after splitting of the cohort according to gender and nodus involvement. We propose that gender differences in ERbeta mRNA expression in tumors during the early stages of CRC can partially explain the lower occurrence of CRC in females compared with males.

Prefrontal cortex and dorsomedial hypothalamus mediate food reward-induced effects via npas2 and egr1 expression in rat.

The effects of food reward on circadian system function were investigated in the hypothalamic nuclei, prefrontal cortex and liver. Food rewards of small hedonic and caloric value were provided for 16 days 3 h after light phase onset to male Wistar rats. The daily pattern of locomotor activity was monitored. Gene expression profiling performed in the dorsomedial hypothalamus (DMH) and liver at the time of reward delivery indicated transcriptional factors egr1 and npas2 as possible mediators of food reward effects. Candidate genes were measured in the suprachiasmatic nuclei (SCN), DMH, arcuate nucleus (ARC), prefrontal cortex (PFC) and liver along with per2 expression. A daily pattern in glycemia and per2 expression in the SCN was emphasized by food reward. The expression of egr1 was rhythmic in the SCN, DMH, PFC and liver and food reward weakened or diminished this rhythm. The expression of npas2 was rhythmic in all tissues except for the PFC where food reward induced rhythm in npas2 expression. Food reward induced npas2 and egr1 expression in the DMH at the time of reward delivery. We suppose that the DMH and PFC participate in the adjustment of the circadian system to utilize food reward-induced input via egr1 and npas2 expression.

Gender-dependent expression of leading and passenger strand of miR-21 and miR-16 in human colorectal cancer and adjacent colonic tissues.

miRNAs are small regulatory RNA molecules involved in posttranscriptional gene silencing. Their biosynthesis results in the formation of duplex consisting of a leading and a passenger strand of mature miRNA. The leading strand exhibits the main activity but recent findings indicate a certain role of the passenger strand as well. Deregulated levels of miRNA were found in many types of cancers including colorectal cancer. miR-21 and miR-16 were indicated as possible markers of colorectal cancer, however, small attention to gender differences in their expression was paid so far. Therefore, the aim of our study was to investigate the expression of miR-21-5p, miR-21-3p, miR-16-5p and miR-16-3p in human colorectal cancer tissue and compare it to the adjacent tissues taken during surgery in men and women separately. Our results showed an up-regulation of all measured miRNAs in tumor tissue compared to adjacent tissues. As expected, tumors and adjacent tissues exhibited a significantly higher expression of leading miRNAs compared to passenger strand of miR-21 and miR-16. The expression of leading and passenger strand of miR-21 and miR-16 positively correlated exhibiting the highest correlation coefficient in the distal tissue. The expression pattern showed gender-dependent differences, with higher levels of miRNA in men than in women. Our findings indicate a gender-related expression pattern of miRNA, which should be considered as an important factor in generating new prognostic or diagnostic biomarkers.