Study On The Expression Of Circadian Gene HClock In Human Colorectal Carcinoma

ObjectiveCircadian gene is a system that sets and regulates circadian rhythm in organisms, as an oscillation with an approximate24-hour cycle. Gene hClock is at the core position of the circadian gene family. Colorectal carcinoma is a common malignancy affecting human health worldwide. The molecular mechanism governing the development of colorectal carcinoma is a multiple-factor and multiple-step process. Studies have revealed that the disruption of circadian rhythms is one of the endogenous factors that contributes to the occurrence and development of colorectal carcinoma, but the molecular changes of it are still unexplored. In this study, the expression of circadian gene, hClock, was examined in colorectal carcinoma and paired normal mucosal tissues, and relationship between gene hClock and tumor related genes with tumor metastasis, pathological classes and clinical grades were also explored. According to the investigation, new theory for tumorigenesis and new target for treatment may be provided.SamplesThe30specimens in this study were obtained from the tumor tissue bank, center of pathological research, institutes of biomedical sciences, Fudan University. The specimens were collected from patients who had radical resection of colorectal carcinoma, from the general surgery department, Huashan hospital affiliated to Fudan University, between January2007and September2008. The specimens were collected between10:00-14:00. The cancer tissue was from the cancer mucosa and the paired non-cancer tissue was from the normal parts of the colorectal mucosa of the same patient. All the patients received no pre-operative treatment and no metastasis. All the tumor issues were confirmed colorectal adenocarcinoma. Complete medical records were collected.Methods1. Quantity analysis the expression of protein hCLOCK in cancers and paired non-cancerous tissues by immuno-fluorescence;2. Analysis the expressions of hClock and tumor related genes (Bak, Bax, Bid, HIF-1α, ARNT, TNFR I, TNFR II and VEGF) mRNA in cancers and paired non-cancerous tissues by real-time quantitative reverse transcription-polymerase chain reaction.Results1. Protein hCLOCK were expressed in all the specimens. Higher expressive level of protein hCLOCK in human colorectal carcinoma than paired non-cancerous tissue. Higher expression of hCLOCK in poor differentiated or late stage of TNM grade of tumors was found, also in64.3%of tumor lymph node metastasis cases.2. Gene hClock were expressed in all the specimens. Significant higher expressive level of gene hClock in human colorectal carcinoma than paired non-cancerous tissue. Gene hClock was significantly positively linear correlated with protein hCLOCK in human colorectal carcinoma.3. Higher expressive level of gene ARNT, HIF-1α, TNFR I, Bak and VEGF, and lower expressive level of gene TNFR II in human colorectal carcinoma. No significant difference between Bax and Bid. Higher expression of ARNT, HIF-1α and VEGF in poor differentiated or late stage of TNM grade of tumors was found, and also high expression of VEGF in the total14cases of tumor lymph node metastasis.4. Gene hClock was significantly positively linear correlated with gene ARNT, HIF-1a and VEGF in human colorectal carcinoma. No significant correlation between hClock and Bak, Bax, Bid, TNFR Ⅰ and TNFR Ⅱ.Conclusions1. Circadian gene hClock were expressed in human colorectal mucosa. 2. Significant higher expressive level of circadian gene hClock in human colorectal carcinoma, and related with progression and lymph node metastasis of cancer.3. Circadian gene hClock may be one of the proto-oncogenes.4. Expression level of circadian gene hClock was positively correlated with some tumor related genes such as HIF-1α, ARNT and VEGF in human colorectal carcinoma.