Discovery of a pyrrole-pyridinimidazole derivative as novel SIRT6 inhibitor for sensitizing pancreatic cancer to gemcitabine.

Pancreatic cancer is a highly aggressive cancer, and is primarily treated with gemcitabine, with increasing resistance. SIRT6 as a member of sirtuin family plays important roles in lifespan and diverse diseases, such as cancer, diabetes, inflammation and neurodegenerative diseases. Considering the role of SIRT6 in the cytoprotective effect, it might be a potential anticancer drug target, and is associated with resistance to anticancer therapy. However, very few SIRT6 inhibitors have been reported. Here, we reported the discovery of a pyrrole-pyridinimidazole derivative, 8a, as a new non-competitive SIRT6 inhibitor, and studied its roles and mechanisms in the antitumor activity and sensitization of pancreatic cancer to gemcitabine. Firstly, we found a potent SIRT6 inhibitor compound 8a by virtual screening and identified by molecular and cellular SIRT6 activity assays. 8a could effectively inhibit SIRT6 deacetylation activity with IC50 values of 7.46 ± 0.79 µM in FLUOR DE LYS assay, and 8a significantly increased the acetylation levels of H3 in cells. Then, we found that 8a could inhibit the cell proliferation and induce cell apoptosis in pancreatic cancer cells. We further demonstrate that 8a sensitize pancreatic cancer cells to gemcitabine via reversing the activation of PI3K/AKT/mTOR and ERK signaling pathways induced by gemcitabine and blocking the DNA damage repair pathway. Moreover, combination of 8a and gemcitabine induces cooperative antitumor activity in pancreatic cancer xenograft model in vivo. Overall, we demonstrate that 8a, a novel SIRT6 inhibitor, could be a promising potential drug candidate for pancreatic cancer treatment.

New brefeldin A-cinnamic acid ester derivatives as potential antitumor agents: Design, synthesis and biological evaluation.

Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and ranks third in mortality rate worldwide. Brefeldin A (BFA, 1), a natural Arf1 inhibitor, qualifies extremely superior antitumor activity against HCC while its low aqueous solubility, poor bioavailability, and high toxicity have greatly hindered its translation to the clinic. Herein, a series of BFA-cinnamic acid ester derivatives was rationally designed and synthesized via introducing active cinnamic acid and its analogues into the structure of 1. Their in vitro cytotoxic activities on five cancer cell lines, including HepG2, BEL-7402, HeLa, Eca-109 and PANC-1, were evaluated using MTT assay. As expected, favorable cytotoxic activity was observed on majority of the mono-substituted derivatives. Especially, the most potent brefeldin A 4-O-(4)-dimethylaminocinnamate (CHNQD-01269, 33) with improved aqueous solubility, demonstrated the strong cytotoxic activity against HepG2 and BEL-7402 cell lines with IC50 values of 0.29 and 0.84 µM, respectively. More importantly, 33 performed low toxicity on normal liver cell line L-02 with the selectivity index (SI) of 9.69, which was more than 17-fold higher than that of 1. Results from mechanistic studies represented that 33 blocked the cell cycle in the G1 phase, and induced apoptosis via elevating reactive oxygen species (ROS) production and increasing expression of apoptosis-related proteins of HepG2 cells. Docking experiment also suggested 33 a promising Arf1 inhibitor, which was confirmed by the cellular thermal shift assay that 33 displayed a significant effect on the stability of Arf1 protein. Furthermore, 33 possessed high safety profile (MTD >100 mg/kg, ip) and favorable pharmacokinetic properties. Notably, the superior antiproliferative activity was verified in HepG2 tumor-bearing xenograft model in which 33 markedly suppressed the tumor growth (TGI = 46.17%) in nude mice at a dose of 10 mg/kg once a day for 16 d. The present study provided evidence of exploiting this series of highly efficacious derivatives, especially 33, for the treatment of HCC.

Aquaporin 5 Facilitates Corneal Epithelial Wound Healing and Nerve Regeneration by Reactivating Akt Signaling Pathway.

Aquaporins (AQPs) are a highly conserved group of membrane proteins that play critical roles in water and small solute transport across epithelial and endothelial barriers. The aim of this study was to determine whether AQP5, a well-known water channel protein, also plays a role in corneal epithelial wound healing. AQP5 knockout (AQP5-/-) mice were generated using CRISPR/Cas9. A corneal wound healing model was established using epithelial debridement of corneas. The time to corneal epithelial and nerve regeneration was significantly delayed in the AQP5-/- mice. Reduction in Ki-67-positive cells and nerve growth factor (NGF) expression was confirmed in the AQP5-/- mice during healing. Epithelial and nerve regeneration rates were significantly increased in the AQP5-/- mice after treatment with NGF, which was accompanied by recovered levels of phosphorylated Akt. NGF treatment also improved the recovery of corneal nerve fiber density and sensitivity in the AQP5-/- mice. While the promotion of NGF induced corneal epithelial and nerve regeneration, Akt inhibitor reversed Akt reactivation. A significant impairment of corneal wound healing in the AQP5-/- mice resulted from distinct defects in corneal epithelial cell proliferation and nerve regeneration. These results provide evidence for the involvement of aquaporin in cell proliferation and suggest that AQP5 induction could be a potential therapy for accelerating the resurfacing of corneal defects.

The transcription factor RUNX2 fuels YAP1 signaling and gastric cancer tumorigenesis.

Despite considerable efforts in the detection and treatment of gastric cancer (GC), the underlying mechanism of the progression of GC remains unknown. Our previous work has demonstrated the remarkable role of Runt-related transcription factor 2 (RUNX2), in fueling the invasion and metastasis of GC. The present study aimed to elucidate the role of RUNX2 in tumorigenesis of GC. We assessed Runx2 expression and its clinical significance via bioinformatic analysis of the Cancer Genome Atlas and Gene Expression Omnibus databases. Roles for Runx2 in self-renewal and tumorigenesis were examined in vitro and in vivo. Further bioinformatic analysis was applied to study the mechanism of GC progression. We found that Runx2 was highly expressed in the early stage of GC and positively correlated with a poor clinical outcome of patients. Runx2 was also significantly correlated with clinicopathological features, such as Hp infection, new neoplastic events, primary therapeutic outcome, ethnicity, race, and tumor stage. Multivariate analysis revealed that together with Runx2, age, cancer status, M stage, and T stage were independent prognostic factors for the outcome of GC patients. RUNX2 overexpression induced increased anchorage-independent colony formation, sphere formation, and tumorigenesis in GC cells in vitro and in vivo. Mechanistically, bioinformatic analysis indicated that yes1 associated transcriptional regulator (YAP1) might be a downstream target of RUNX2. Specific knockdown of YAP1 reduced the tumor-initiating ability of GC cells induced by ectopic Runx2 expression. Our findings support the hypothesis that RUNX2 exerts oncogenic properties via YAP1 regulation, highlighting essential roles for RUNX2 and YAP1 in gastric carcinogenesis and suggesting potential therapeutic targets.

Elevated LOXL2 expression by LINC01347/miR-328-5p axis contributes to 5-FU chemotherapy resistance of colorectal cancer.

Chemotherapy resistance after curative surgery is a major contributor to the mortality of colorectal cancer (CRC). Detailed mechanism studies of specific molecular alterations are critical to improving the available therapies for long-term disease administration. We explored the functional role of LINC01347 in chemotherapy resistance of CRC. Elevated LINC01347 expression was correlated with CRC disease progression during chemotherapy treatment. However, the functional role of LINC01347 and mechanism remained undefined. In this study, we demonstrated that elevated LINC01347 expression was correlated with late clinical stage and poor prognosis in CRC tumor tissues with TCGA data. Exogenous LINC01347 expression promoted cell proliferation and 5-FU resistance of CRC cells, while LINC01347 knockdown attenuated cell growth and 5-FU resistance in vitro and in vivo. Molecular analysis indicated that LINC01347 participated in the transcriptional regulation of LOXL2 by sponging miR-328-5p. LOXL2 knockdown impaired the LINC01347 overexpression induced 5-FU resistance in CRC cells. The clinical analysis supported miR-328-5p/LOXL2 as a candidate biomarker for chemotherapy resistance of CRC patients. Our study provided a molecular basis for the development of 5-FU based chemotherapy resistance in CRC by LINC01347/miR-328/LOXL2 axis. We identified LINC01347 as a prognostic biomarker and potential therapeutic target against 5-FU based chemotherapy resistance of CRC.