Statins abrogate gemcitabine-induced PD-L1 expression in pancreatic cancer-associated fibroblasts and cancer cells with improved therapeutic outcome.

A combination of chemotherapy with immunotherapy has been proposed to have better clinical outcomes in Pancreatic Ductal Adenocarcinoma (PDAC). On the other hand, chemotherapeutics is known to have certain unwanted effects on the tumor microenvironment that may mask the expected beneficial effects of immunotherapy. Here, we have investigated the effect of gemcitabine (GEM), on two immune checkpoint proteins (PD-L1 and PD-L2) expression in cancer associated fibroblasts (CAFs) and pancreatic cancer cells (PCCs). Findings of in vitro studies conducted by using in-culture activated mouse pancreatic stellate cells (mPSCs) and human PDAC patients derived CAFs demonstrated that GEM significantly induces PD-L1 and PD-L2 expression in these cells. Moreover, GEM induced phosphorylation of STAT1 and production of multiple known PD-L1-inducing secretory proteins including IFN-γ in CAFs. Upregulation of PD-L1 in PSCs/CAFs upon GEM treatment caused T cell inactivation and apoptosis in vitro. Importantly, Statins suppressed GEM-induced PD-L1 expression both in CAFs and PCCs while abrogating the inactivation of T-cells caused by GEM-treated PSCs/CAFs. Finally, in an immunocompetent syngeneic orthotopic mouse pancreatic tumor model, simvastatin and GEM combination therapy significantly reduced intra-tumor PD-L1 expression and noticeably reduced the overall tumor burden and metastasis incidence. Together, the findings of this study have provided experimental evidence that illustrates potential unwanted side effects of GEM that could hamper the effectiveness of this drug as mono and/or combination therapy. At the same time the findings also suggest use of statins along with GEM will help in overcoming these shortcomings and warrant further clinical investigation.

ATAD2 suppression enhances the combinatorial effect of gemcitabine and radiation in pancreatic cancer cells.

Amalgamation of target-based approach along with chemo and/or radiotherapy could be an effective strategy to combat pancreatic cancer (PC). ATAD2 (ATPase family AAA domain containing 2) is a potential oncoprotein and a poor prognostic factor in PC. ATAD2 inhibition sensitizes pancreatic cancer cells (PCCs) to gemcitabine (GEM). ATAD2 silencing also enhances radio-sensitivity in lung cancer cells. We therefore hypothesise that ATAD2 suppression along with application of GEM and radiation could show additive/synergistic response in reducing PC progression. At first, immunofluorescence and western blot analysis are carried out to investigate ATAD2 expression upon irradiation in PCCs (BxPC3, and PANC1). Colony forming assay is performed to analyse the radio-sensitization effect of ATAD2 suppressed PCCs in absence and presence of GEM. To evaluate the consequences of irradiation, expression of markers for DNA damage and repair as well as apoptosis and autophagy are also assessed. Results indicate that ATAD2 is elevated in irradiated PCCs. Silencing ATAD2 sensitizes PCCs to radiation. Survival fraction analysis of PCCs shows that combination treatment of GEM and radiation (with minimal doses) is more effective when ATAD2 is suppressed. Further, when GEM-radiation combination is applied to ATAD2 silenced PCCs, expression of DNA damage marker like γH2AX is induced, whereas DNA damage repair proteins (pChk1, and pChk2) are downregulated. Moreover, ATAD2 suppressed PCCs are more susceptible to apoptosis and autophagy in presence of radiation and GEM. Collectively, these findings support our hypothesis and demonstrate that targeting ATAD2 enhances efficacy of GEM-radiation treatment in PCCs.

MicroRNA-217 modulates pancreatic cancer progression via targeting ATAD2.

AIMS: Pancreatic cancer is a fatal disease across the world with 5 years survival rate less than 10%. ATAD2, a valid cancer drug-target, is overexpressed in pancreatic malignancy with high oncogenic potential. However, the mechanism of the upregulated expression of ATAD2 in pancreatic cancer is unknown. Since microRNAs (miRNAs) could potentially control target mRNA expressions, and are involved in cancer as tumor-suppressors, oncomiR or both, we examine the possibility of miRNA-mediated regulation of ATAD2 in pancreatic cancer cells (PCCs). MAIN METHODS: Our in-silico approach first identifies hsa-miR-217 as a candidate regulator for ATAD2 expression. For further validation, luciferase reporter assay is performed. We overexpress hsa-miRNA-217 and assess cellular viability, migration, apoptosis and cell cycle progression in three different PCCs (BxPC3, PANC1, and MiaPaCa2). KEY FINDINGS: We find hsa-miRNA-217 has potential binding site at the 3'UTR of ATAD2. Luciferase assay confirms that ATAD2 is a direct target of hsa-miR-217. Overexpression of hsa-miR-217 drastically downregulates ATAD2 expression in PCCs, thus, corroborating binding studies. The elevated expression of hsa-miRNA-217 diminishes cell proliferation and migration as well as induces apoptosis and cell cycle arrest in PCCs. Finally, siRNA mediated ATAD2 knockdown or overexpression of hsa-miRNA-217 in PCCs showed inactivation of the AKT signaling pathway. Therefore, hsa-miR-217 abrogates pancreatic cancer progression through inactivation of the AKT signaling pathway and this might be partly due to miR-217 mediated suppression of ATAD2 expression. SIGNIFICANCE: The application of hsa-miR-217 mimic could be a promising therapeutic strategy for the treatment of pancreatic cancer patients in near future.

Emerging oncogene ATAD2: Signaling cascades and therapeutic initiatives.

ATAD2 is a promising oncoprotein with tumor-promoting functions in many cancers. It is a valid cancer drug-target and a potential cancer-biomarker for multiple malignancies. As a cancer/testis antigen (CTA), ATAD2 could also be a probable candidate for immunotherapy. It is a unique CTA that belongs to both AAA+ ATPase and bromodomain family proteins. Since 2007, several research groups have been reported on the pleiotropic oncogenic functions of ATAD2 in diverse signaling pathways, including Rb/E2F-cMyc pathway, steroid hormone signaling pathway, p53 and p38-MAPK-mediated apoptotic pathway, AKT pathway, hedgehog signaling pathway, HIF1α signaling pathway, and Epithelial to Mesenchymal Transition (EMT) pathway in various cancers. In all these pathways, ATAD2 participates in chromatin dynamics, DNA replication, and gene transcription, demonstrating its role as an epigenetic reader and transcription factor or coactivator to promote tumorigenesis. However, despite the progress, an overall mechanism of ATAD2-mediated oncogenesis in diverse origin is elusive. In this review, we summarize the accumulated evidence to envision the overall ATAD2 signaling networks during carcinogenesis and highlight the area where missing links await further research. Besides, the structure-function aspect of ATAD2 is also discussed. Since the efforts have already been initiated to explore targeted drug molecules and RNA-based therapeutic alternatives against ATAD2, their potency and prospects have been elucidated. Together, we believe this is a well-rounded review on ATAD2, facilitating a new drift in ATAD2 research, essential for its clinical implication as a biomarker and/or cancer drug-target.

Crystallization and preliminary X-ray analysis of cyclophilin from Leishmania donovani.

Cyclophilin from the parasite Leishmania donovani is a protein with peptidylprolyl cis-trans isomerase activity, in addition to being a receptor for the drug cyclosporin. Crystals of the enzyme have been obtained in space group P4(3)2(1)2, with unit-cell parameters a = b = 48.73, c = 140.93 A, and diffract to 3.5 A resolution. One molecule per asymmetric unit gives a solvent content and Matthews coefficient of 46% and 2.3 A(3) Da(-1), respectively. Molecular-replacement calculations with human cyclophilin A as the search model give an unambiguous solution in rotation and translation functions.