OBJECTIVES: Numerous studies have demonstrated that fasting serum glucose (FSG) levels and certain single-nucleotide polymorphisms (SNPs) are related to an increased risk of colorectal cancer (CRC); however, their combined effects are still unclear. METHODS: Of a total of 144,527 men and women free of cancer at baseline, 317 developed CRC during 5.3 years of follow-up. A case-cohort study (n=1,691) was used, consisting of participants with a DNA sample available. Three well-known SNPs (rs3802842, rs6983267, rs10795668) were genotyped. Hazard ratios (HR) and 95% confidence intervals (CI) of CRC, colon and rectal cancer were calculated, with the Cox proportional hazard models. RESULTS: The crude incidence rates per 100,000 person-years were 41.1 overall, 48.4 for men, and 29.3 for women. Among participants with dysglycemia, SNPs rs3802842 and rs6983267 were both associated with an increased risk of CRC (HR, 3.2; 95% CI, 1.9 to 5.5 and HR, 1.8; 95% CI, 1.1 to 3.1, respectively) and rectal cancer (HR, 3.4; 95% CI, 1.8 to 6.6 and HR, 3.3; 95% CI, 1.6 to 7.1, respectively). The interaction effect of dysglycemia and SNPs was positive, that is, resulted in an elevated risk of CRC, but was not statistically significant. CONCLUSIONS: This study demonstrates that both high FSG and certain SNPs are major risk factors for CRC and rectal cancer but that they did not interact synergistically. The difference in effect size of the SNPs according to CRC subtype (i.e., colon or rectal cancer) and presence of dysglycemia merits further research.
Blood Glucose ; Colon ; Colorectal Neoplasms* ; DNA ; Fasting* ; Female ; Follow-Up Studies ; Glucose* ; Humans ; Incidence ; Male ; Polymorphism, Single Nucleotide ; Proportional Hazards Models ; Rectal Neoplasms ; Risk Factors

It has been reported that a change in the cellular redox state may be involved in the regulation of vascular tone, but the underlying mechanism is not fully understood. The present study was designed to investigate the cellular effect of sulfhydryl modifying agents in the coronary artery of rabbit using the tension measurement and whole cell clamping method. The application of diamide, a sulfhydryl oxidizing agent, relaxed the endothelium denuded coronary arteries in a dose dependent manner. The fact that this diamide-induced relaxation was significantly attenuated by a pretreatment of 4-AP, and the coronary arteries precontracted with 100 mM K+ instead of histamine, suggests the involvement of 4-AP sensitive K+ channels in the diamide-induced relaxation of coronary arteries. Whole cell patch clamp studies revealed that the 4-AP sensitive IdK was significantly enhanced by the membrane permeant oxidizing agents, diamide and DTDP, and were reversed by subsequent exposure to the reducing agent, DTT. Neither the membrane impermeant oxidizing or reducing agents, GSSG or GSH, had any effect on the activity of IdK, indicating that intracellular sulfhydryl modification is critical for modulating IdK activity. The Diamide failed to significantly alter the voltage dependence of the activation and inactivation parameters, and did not change the inactivation process, suggesting that diamide increases the number of functional channels without altering their gating properties. Since IdK has been believed to play an important role in regulating membrane potential and arterial tone, our results about the effect of sulfhydryl modifying agents on coronary arterial tone and IdK activity should help understand the pathophysiology of the diseases, where oxidative damage has been implicated.
Animal ; Arteries/physiology ; Arteries/drug effects ; Arteries/cytology ; Coronary Vessels/physiology ; Coronary Vessels/drug effects* ; Coronary Vessels/cytology ; Female ; Male ; Oxidants/pharmacology* ; Potassium Channels/physiology ; Rabbits ; Reducing Agents/pharmacology* ; Sulfhydryl Compounds/metabolism*