Discovery of novel hydroxyamidine based indoleamine 2,3-dioxygenase 1 (IDO1) and thioredoxin reductase 1 (TrxR1) dual inhibitors.

In order to take advantage of both immunotherapeutic and metabolic antitumor agents, novel dual indoleamine 2,3- dioxygenase 1 (IDO1) and thioredoxin reductase 1 (TrxR1) inhibitors were designed. Thioredoxin reductase 1 (TrxR1) is a main ROS modulator within CRC cells. Indoleamine 2,3-dioxygenase (IDO1) is crucial controller for tryptophan (Trp) metabolism that is also important for CRC immunotherapy. Herein, ten compounds 12a-j containing hydroxyamidine scaffold were designed, synthesized and evaluated for inhibitory activities against IDO1/TrxR1 enzyme and CRC cells. Among these compounds, the most active compound 12d (ZC0109) showed excellent and balanced activity against both IDO1 (IC50 = 0.05 µM) and TrxR1 (IC50 = 3.00 ± 0.25 µM) were selected for further evaluation. Compound ZC0109 exhibited good dual inhibition against IDO1 and TrxR1 both in vitro and in vivo. Further mechanistic studies reveal that, through IDO1 and TrxR1 inhibition by ZC0109 treatment, accumulated ROS effectively induced apoptosis and G1/S cell cycle arrest in cancer cells. In vivo evaluation demonstrated excellent anti-tumor effect of ZC0109 with the notable ability of promoting ROS-induced apoptosis, reducing kynurenine level in plasma and restoring anti-tumor immune response. Thus, ZC0109 represents a potential CRC therapy agent for further development.

Design, synthesis, and biological evaluation of a novel indoleamine 2,3-dioxigenase 1 (IDO1) and thioredoxin reductase (TrxR) dual inhibitor.

Targeting the Trp-Kyn pathway is an attractive approach for cancer immunotherapy. Thioredoxin reductase (TrxR) enzymes are reactive oxygen species (ROS) modulators that are involved in the tumor cell growth and survival processes. The 4-phenylimidazole scaffold is well-established as useful for indoleamine 2,3-dioxygenase 1 (IDO1) inhibition, while piperlongumine (PL) and its derivatives have been reported to be inhibitors of TrxR. To take advantage of both immunotherapy and TrxR inhibition, we designed a first-generation dual IDO1 and TrxR inhibitor (ZC0101) using the structural combination of 4-phenylimidazole and PL scaffolds. ZC0101 exhibited better dual inhibition against IDO1 and TrxR in vitro and in cell enzyme assays than the uncombined forms of 4-phenylimidazole and PL. It also showed antiproliferative activity in various cancer cell lines, and a selective killing effect between normal and cancer cells. Furthermore, ZC0101 effectively induced apoptosis and ROS accumulation in cancer cells. Knockdown of TrxR1 and IDO1 expression induced cellular enzyme inhibition and ROS accumulation effects during ZC0101 treatment, but only reduced TrxR1 expression was able to improve ZC0101's antiproliferation effect. This proof-of-concept study provides a novel strategy for cancer treatment. ZC0101 represents a promising lead compound for the development of novel antitumor agents that can also be used as a valuable probe to clarify the relationships and mechanisms of cancer immunotherapy and ROS modulators.

Piperlongumine Inhibits Akt Phosphorylation to Reverse Resistance to Cisplatin in Human Non-Small Cell Lung Cancer Cells via ROS Regulation.

Resistance is a major concern when administering chemotherapy to patients with non-small cell lung cancer (NSCLC). Chemosensitizer are agents that can reverse resistance to chemotherapeutic drugs, thereby enhancing the chemosensitivity of tumor cells. Thus, their development will improve therapeutic efficacy in cancer. However, few effective chemosensitizer have been identified to date. Piperlongumine (PL) has been shown to effectively reverse resistance to chemotherapeutic drugs in several types of cancers. However, the mechanisms associated with the chemotherapy resistance reversal effect of PL and its regulation of target factors in chemotherapy resistance cells are still unclear. This study investigated the reversal effect of PL both in vitro and in vivo, and provided evidence that PL inhibited the phosphorylation of Akt via the accumulation of reactive oxygen species in chemotherapy resistance cells. Consequently, various Akt activation-dependent genes caused a reduction of drug efflux and induction of apoptosis in cisplatin-resistant A549 NSCLC cells. Our results indicate that Akt phosphorylation may play a functional role in the reversal effect of PL and contribute, at least in part, to the treatment outcomes of patients with chemotherapy resistance.

Shape-based virtual screen for the discovery of novel CDK8 inhibitor chemotypes.

With the aim of discovering novel cyclin-dependent kinase 8 (CDK8) inhibitors, a combined similarity search and molecular docking approach was employed, which led to 32 hits. Biological tests led to the discovery of several novel submicromolar inhibitors. In particular, compound C768-0769 (ZC0201) showed good CDK8 inhibitory activity, and compound ZC0201 effectively suppressed HCT-116 colorectal cancer cell proliferation by inducing G1/S transition arrest. Furthermore, modulation of phosphorylated signal transducer and activator of transcription 1 (Ser 727) (STAT1SER727), a pharmacodynamic biomarker of CDK8 activity, demonstrated that ZC0201 may cause G1/S transition arrest through CDK8 activity inhibition. Due to its good cellular activity, ZC0201 may be an ideal lead compound for further modification as a potential cancer therapeutic agent.

Nrf2 is a key factor in the reversal effect of curcumin on multidrug resistance in the HCT­8/5­Fu human colorectal cancer cell line.

Multidrug resistance (MDR) is a major concern when using chemotherapy for the treatment of patients with colorectal cancer. MDR modulators are agents that can reverse MDR and, thus, enhance the chemosensitivity of tumor cells. The development of MDR modulators can improve the therapeutic efficacies of MDR in cancer. However, few effective MDR modulators have been identified so far. Curcumin has been reported to be an effective compound in the reversal of MDR in colorectal cancer cells. However, the mechanisms associated with the reversal effect of curcumin on MDR and its regulation of target factors in MDR cells remain to be fully elucidated. 3­(4,5­dimethyl­2­thiazol)­2,5­diphenyltetrazolium bromide assays, flow cytometer apoptosis assays as well as mRNA and protein expression assays were performed in the present study, and the results confirmed the reversal effect of curcumin on HCT­8/5­Fu cells and provided evidence that activated nuclear factor erythroid 2­related factor (Nrf2) deficiency induced by the curcumin altered the B­cell lymphoma 2 (Bcl­2) associated X protein/Bcl­2 expression ratio, which led to the induction of apoptosis in HCT­8/5­Fu cells. These results indicated that Nrf2 may have a functional in the reversal effect of curcumin and contribute, at least in part, to the outcomes of chemotherapy in patients with MDR.