Author Interviews, Brigham & Women's - Harvard, Pancreatic, Weight Research / 10.07.2016
Study Identifies Pathway Linking Obesity With Pancreatic Cancer Progression
MedicalResearch.com Interview with;
Dr. Rakesh K. Jain, PhD
A.W.Cook Professor of Radiation Oncology (Tumor Biology)
Director, E.L. Steele Laboratory
Department of Radiation Oncology
Harvard Medical School and
Massachusetts General Hospital
Boston, MA 02114
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer death worldwide, and more than half of patients diagnosed with PDAC are overweight or obese. Among patients with PDAC, obesity more than doubles the already high risk of death, and our work aims to reveal the underlying mechanisms. Specifically, we identified that obesity increases desmoplasia – an accumulation of connective tissue and inflammation – hallmark of Pancreatic ductal adenocarcinoma and discovered underlying mechanisms.
In our report published online in Cancer Discovery, we describe how interactions among fat cells, immune cells and connective tissue cells in obese individuals create a microenvironment that promotes tumor progression while diminishing the response to chemotherapy. We demonstrated the negative impact of obesity on numerous aspects of tumor growth, progression and treatment response in several animal models of pancreatic ductal adenocarcinoma and confirmed some of our findings in samples from cancer patients. Along with finding that tumors from obese mice or patients exhibited elevated levels of adipocytes or fat cells and of desmoplasia, both of which fuel tumor progression and interfere with treatment response, we identified the underlying causes.
The elevated desmoplasia in obese mouse models of PDAC was caused by the activation of pancreatic stellate cells through the angiotensin II type-1 receptor (AT1) signaling pathway. This activation was induced by interleukin-1 beta (IL-1ß) produced by fat cells as well as the immune cells called neutrophils within tumors. Inhibiting AT1 signaling with losartan, which is used clinically to treat hypertension, or the blockade of IL-1ß reduced obesity-associated desmoplasia and tumor growth and increased the response to chemotherapy in the obese mouse model but not in normal weight animals. Analysis of tumors from human PDAC patients revealed increased desmoplasia and fat deposits in samples from obese patients, and data from more than 300 patients showed that excess weight was associated with a reduction in patients.
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