The Therapeutic Potentials And Mechanism Of PI3Kγ Inhibitor AS605240 On Mice Pancreatic Cancer

Background and purpose: In recent years, the incidence of pancreatic cancer increases year by year, as a kind of tumor with a very poor prognosis and neither sensitive to radiotherapy nor chemotherapy. There is an urgent need for more effective therapy treatment. Pancreatic cancer has several obvious features at the genetic level. One of these is K-Ras gene mutation which to be detected during the occurrence and progress of 75%-90% pancreatic cancers. The key downstream target of Ras family is PI3K(phosphoinositide 3-kinase). PI3 K is in a position to activate protease Akt, thereby activating the pancreatic cancer invasiveness. Recent studies have found novel thiazolidinediones ketones AS605240 is a highly selective inhibitor of PI3Kγ. AS605240 can strongly inhibit tumor angiogenesis in human umbilical vein endothelial cells(HUVECs) or the growth of mouse neuroblastoma, also effectively induce apoptosis in a variety of neuroblastoma tumor cells, and shows outstanding anti-inflammatory effect in pancreatitis, ulcerative colitis, autoimmune hepatitis and pulmonary fibrosis without apparent toxicity in mouse model. Because angiogenesis, evasion of apoptosis, chronic inflammation are important steps during tumor incidence, while p110γ is highly expressed in pancreatic cancer cell lines and pancreatic tumor tissue we assume AS605240 could be an efficiently medication without obvious side effects. Currently, research of AS605240 treatment for pancreatic cancer has not been reported neither domestically nor abroad. Therefore, we use mice to build pancreatic cancer xenograft model, first studied AS605240 therapeutic effect in vivo model of pancreatic cancer and to explore the possible molecular mechanism for the AS605240. In order to lay a solid foundation for developing AS605240 into a good pancreatic cancer chemopreventive medication.Methods: First, we use MTT to test the inhibitory effect on the growth of human pancreatic cancer cell line PANC1 by AS605240 in vitro. Then, we start the animal experiment. Pancreatic cancer xenograft mice were randomly divided into four groups after established:Vehicle-treated control group, AS605240-treated group, AS605240 and 5-FU-combine treated group, 5-FU-treated group. Tumor volume is measured every 2 days after the beginning of the experiment. Tumor growth curve is drawn simultaneously. Mice are sacrificed on the 30 th day. We strip out the tumor tissue and weighed to calculate the inhibition rate. Mice visceral organs are taken out and saved. HE staining is used to detect organs and tumor histopathological changes in mice. Immunohistochemical staining serves to detect Cyclin D1, Ki-67, β-catenin, expression levels. TUNEL kits and caspase-3 immunofluorescence staining are used to detect the apoptosis of tumor tissue. CD11 b immunofluorescence staining serves to observe the changes of myeloid derived suppressor cells in the tumor tissue. F4/80 immunofluorescence staining serves to observe the changes of macrophages cells in the tumor tissue. And then double immunofluorescence staining is used to detect changes in M1 type macrophages, M2 type macrophages and tumor-associated cytokines(IFN-γ, IL-10, MMP-9, VEGF) in tumor microenvironment. Meanwhile CD31 immunofluorescence is given to observe angiogenesis in tumor tissue. Finally, RT-PCR is served to detect the mRNA expression of iNOS, IFN-γ, MR, IL-10, VEGF, MMP-9 in tumor tissue.Results: In the experiment, the tumor volume is significantly reduced in AS605240 treatment group and combined treatment group. The survival time of mice has been extended. Neither HE staining nor immunohistochemical staining shows no difference between AS605240 treatment group and control group. Tunel and caspase-3 immunofluorescence show no significant effect on apoptosis of tumor tissue during AS605240 treatment. AS605240 treatment can significantly reduce the number of CD11b-positive and F4/80-positive cells in tumor tissue, especially reducing the number of M2 type of tumor associated macrophages without affecting the number of M1 tumor associated macrophages cell. IL-10-positive cells, MMP-9-positived cells have a significant reduction, while IFN-γ-positive cells changed slightly. PCR demonstrates that IL-10, MMP-9, VEGF mRNA expression reduced without affecting IFN-γ mRNA expression during AS605240 treatment. Simultaneously, AS605240 treatment significantly reduced the number of CD31-positive cells in the tumor tissue.Conclusions:1. AS605240 can suppress tumor growth in mice and prolong the survival time of mice to a certain extent.2. AS605240 has no significant side effects in mice.3. AS605240 has no significant effect on the growth of tumor cells in vitro4. AS605240 has no significant effect on Ki-67, Cyclin D1, β-catenin protein expression in tumor tissue.5. AS605240 has no significant effect on tumor apoptosis.6. AS605240 can significantly reduce the number of myeloid derived suppressor cells and M2 type tumor associated macrophages in tumor tissue. without affecting M1 type tumor associated macrophages in tumor tissue.7. AS605240 can reduce the expression of tumor-promoting cytokines IL-10, MMP-9, VEGF mRNA, without affecting tumor suppression pathway cytokines IFNγ mRNA expression.8. AS605240 can significantly inhibit tumor angiogenesis.9. The experiment provides a new way of pancreatic cancer treatment.