Uncoupling protein 2 deficiency of non-cancerous tissues inhibits the progression of pancreatic cancer in mice

Background: Pancreatic ductal adenocarcinoma(PDAC) is a disease of the elderly mostly because its development from preneoplastic lesions depends on the accumulation of gene mutations and epigenetic alterations over time. How aging of non-cancerous tissues of the host affects tumor progression, however, remains largely unknown. Methods: We took advantage of a model of accelerated aging, uncoupling protein 2-deficient( Ucp2 knockout, Ucp2 KO) mice, to investigate the growth of orthotopically transplanted Ucp2 wild-type(WT) PDAC cells(cell lines Panc02 and 6606PDA) in vivo and to study strain-dependent differences of the PDAC microenvironment. Results: Measurements of tumor weights and quantification of proliferating cells indicated a significant growth advantage of Panc02 and 6606PDA cells in WT mice compared to Ucp2 KO mice. In tumors in the knockout strain, higher levels of interferon-γ m RNA despite similar numbers of tumor-infiltrating T cells were observed. 6606PDA cells triggered a stronger stromal reaction in Ucp2 KO mice than in WT animals. Accordingly, pancreatic stellate cells from Ucp2 KO mice proliferated at a higher rate than cells of the WT strain when they were incubated with conditioned media from PDAC cells. Conclusions: Ucp2 modulates PDAC microenvironment in a way that favors tumor progression and implicates an altered stromal response as one of the underlying mechanisms.

Impact of hyperglycemia on autoimmune pancreatitis and regulatory T-cells

AIM To evaluate the influence of hyperglycemia on the progression of autoimmune pancreatitis.METHODS We induced hyperglycemia by repetitive intraperitoneal(ip) injection of 50 mg/kg streptozotocin in MRL/Mp J mice, which develop autoimmune pancreatitis due to a genetic predisposition. We compared the extent of inflammation(histological score, CD3^+ lymphocytes, CD8^+ T-cells, CD4^+ T-cells, Foxp3^+ T-helper cells) in the pancreas of hyperglycemic and normoglycemic mice. We also analyzed the number of leukocytes, lymphocytes, granulocytes and monocytes in the blood. In addition, we determined the percentage of CD3^+ lymphocytes, CD8^+ T-cells, CD4^+ T-cells, Foxp3^+ T-helper cells, Foxp3^+ CD25^+ T-helper and Foxp3^+T-helper cells in the spleen by flow cytometry.RESULTS Treatment with streptozotocin caused a strong induction of hyperglycemia and a reduction in body weight(P < 0.001). Severe hyperglycemia did not, however, lead to an aggravation, but rather to a slight attenuation of autoimmune pancreatitis. In the pancreas, both the histological score of the pancreas as well as the number of CD3+ lymphocytes(P < 0.053) were decreased by hyperglycemia. No major changes in the percentage of CD8^+ T-cells, CD4^+ T-cells, Foxp3^+ T-helper cells were observed between hyperglycemic and normoglycemic mice. Hyperglycemia increased the numbers of leukocytes(P < 0.001), lymphocytes(P = 0.016), granulocytes and monocytes(P = 0.001) in the blood. Hyperglycemia also moderately reduced the percentage of CD3^+ lymphocytes(P = 0.057), significantly increased the percentage of Foxp3^+ T-helper cells(P = 0.018) and Foxp3^+ CD25^+ T-helper cells(P = 0.021) and reduced the percentage of Foxp3^+T-helper cells(P = 0.034) in the spleen. CONCLUSION Hyperglycemia does not aggravate but moderately attenuates autoimmune pancreatitis, possibly by increasing the percentage of regulatory T-cells in the spleen.