Uncoupling protein 2 deficiency reduces proliferative capacity of murine pancreatic stellate cells

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 mRNA 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.

Plant-Derived Anticancer Agents: Lessons from the Pharmacology of Geniposide and Its Aglycone, Genipin

For centuries, plants have been exploited by mankind as sources of numerous cancer chemotherapeutic agents. Good examples of anticancer compounds of clinical significance today include the taxanes (e.g., taxol), vincristine, vinblastine, and the podophyllotoxin analogues that all trace their origin to higher plants. While all these drugs, along with the various other available therapeutic options, brought some relief in cancer management, a real breakthrough or cure has not yet been achieved. This critical review is a reflection on the lessons learnt from decades of research on the iridoid glycoside geniposide and its aglycone, genipin, which are currently used as gold standard reference compounds in cancer studies. Their effects on tumour development (carcinogenesis), cancer cell survival, and death, with particular emphasis on their mechanisms of actions, are discussed. Particular attention is also given to mechanisms related to the dual pro-oxidant and antioxidant effects of these compounds, the mitochondrial mechanism of cancer cell killing through reactive oxygen species (ROS), including that generated through the uncoupling protein-2 (UCP-2), the inflammatory mechanism, and cell cycle regulation. The implications of various studies for the evaluation of glycosidic and aglycone forms of natural products in vitro and in vivo through pharmacokinetic scrutiny are also addressed.

The anti-proliferative effects of oleanolic acid on A7r5 cells-Role of UCP2 and downstream FGF-2/p53/TSP-1

Vascular smooth muscle cell (VSMC) proliferation is a major contributor to atherosclerosis. This study investigated the inhibitory effects of oleanolic acid (OA) against oxidized low-density lipoprotein (ox-LDL)-induced VSMC proliferation in A7r5 cells and explored underlying molecular mechanism. The cell proliferation was quantified with cell counting kit-8 (CCK-8), in which ox-LDL significantly increased A7r5 cells proliferation, while OA pretreatment effectively alleviated such changes without inducing overt cytotoxicity, as indicated by lactate dehydrogenase (LDH) assay. Quantitative real-time RT-PCR (qRT-PCR) and Western blotting revealed increased UCP2 and FGF-2 expression levels as well as decreased p53 and TSP-1 expression levels in A7r5 cells following ox-LDL exposure, while OA pretreatment reversed such changes. Furthermore, inhibiting UCP2 with genipin remarkably reversed the changes in the expression levels of FGF-2, p53, and TSP-1 induced by ox-LDL exposure; silencing FGF-2 with siRNA did not significantly change the expression levels of UCP2 but effectively reversed the changes in the expression levels of p53 and TSP-1, and activation of p53 with PRIMA-1 only significantly affected the changes in the expression levels of TSP-1, but not in UCP2 or FGF-2, suggesting a UCP-2/FGF-2/p53/TSP-1 signaling in A7r5 cells response to ox-LDL exposure. Additionally, co-treatment of OA and genipin exhibited similar effects to the expression levels of UCP2, FGF-2, p53, and TSP-1 as OA or genipin solo treatment in ox-LDL-exposed A7r5 cells, suggesting the involvement of UCP-2/FGF-2/p53/TSP-1 in the mechanism of OA. In conclusion, OA inhibits ox-LDL-induced VSMC proliferation in A7r5 cells, the mechanism involves the changes in UCP-2/FGF-2/p53/TSP-1.