MedicalResearch.com Interview with:
Dr. Xifeng Wu, MD PhD
Department Chair, Department of Epidemiology, Division of OVP, Cancer Prevention and Population Sciences
Director, Center for Translational and Public Health Genomics
Professor, Department of Epidemiology
Division of Cancer Prevention and Population Sciences
The University of Texas MD Anderson Cancer Center, Houston, Texas
Medical Research: What is the background for this study? What are the main findings?
Dr. Wu: Obesity is a well-established risk factor for renal cell carcinoma (RCC), the most common form of kidney cancer. It has been estimated that more than 40% of RCC incident cases in the US may be attributed to excessive body weight. Growing body of evidence suggests that obesity may also influence clinical outcome of RCC; however, the findings are sometimes conflicting. So far, the molecular mechanism linking obesity to RCC risk or prognosis is not well understood. In this study, we evaluated the promoter CpG site methylation of 20 candidate obesity-related genes and their association with RCC risk and recurrence in a two-phase study of 240 newly diagnosed, previously untreated RCC patients. Pyrosequencing was conducted on paired RCC tumor and normal adjacent tissues to measure promoter methylation. Among the 20 markers, we found
NPY,
LEP and
LEPR showed significant differential methylation levels between tumors and normal adjacent tissues, and methylation was significantly higher in tumors in both discovery and validation groups. Consistent with our findings, we also found lower expression of
LEPR in tumor tissues compared to normal adjacent tissues in data obtained from The Cancer Genome Atlas. Additionally, high
LEPR methylation in tumors was associated with more advanced tumor features, such as high pathologic stage, high grade and clear cell RCC histology, and increased risk of recurrence compared to the low methylation group. These results suggest that tissue changes in promoter methylation in obesity-related genes may provide some biological basis for the association between obesity and RCC outcome, and that
LEPR may be an independent prognostic indicator of recurrence in RCC patients. Further research in larger study population and functional studies are warranted to validate our findings and to elucidate the underlying causal mechanisms.
(more…)