Small molecular CD73 inhibitors: Recent progress and future perspectives.

The occurrence and development of the tumor are very complex biological processes. In recent years, a large number of research data shows that CD73 is closely related to tumor growth and metastasis. It has been confirmed that the cascade hydrolysis of extracellular ATP to adenosine is one of the most important immunosuppressive regulatory pathways in the tumor microenvironment. The metabolite adenosine can mediate immunosuppression by activating adenosine receptor (such as A2A) on effector Immune cells and enable tumor cells to achieve immune escape. Therefore, attenuating or completely removing adenosine-mediated immunosuppression in the tumor microenvironment by inhibiting CD73 is a promising approach in the treatment of solid tumors. This paper focuses on the research progress of CD73 enzyme and CD73 small molecule inhibitors, and is expected to provide some insights into the development of small-molecule antitumor drugs targeting CD73.

Discovery of (quinazolin-6-yl)benzamide derivatives containing a 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline moiety as potent reversal agents against P-glycoprotein-mediated multidrug resistance.

P-glycoprotein (P-gp) is an important factor leading to multidrug resistance (MDR) in cancer treatment. The co-administration of anticancer drugs and P-gp inhibitors has been a treatment strategy to overcome MDR. In recent years, tyrosine kinase inhibitor Lapatinib has been reported to reverse MDR through directly interacting with ABC transporters. In this work, a series of P-gp inhibitors (1-26) was designed and synthesized by integrating the quinazoline core of Lapatinib into the molecule framework of the third-generation P-gp inhibitor Tariquidar. Among them, compound 14 exhibited better MDR reversal activity than Tariquidar. The docking results showed compound 14 displayed the L-shaped molecular conformation. Importantly, compound 14 increased the accumulation of Adriamycin (ADM) and rhodamine 123 (Rh123) in MCF7/ADM cells. Besides, compound 14 significantly increased ADM-induced apoptosis and inhibited the proliferation, migration and invasion of MCF7/ADM cells. It was also demonstrated that compound 14 significantly inhibited the growth of MCF7/ADM xenograft tumors by increasing the sensitivity of ADM. In summary, compound 14 has the potential to overcome MDR caused by P-gp.

A possible covalent xanthine oxidase inhibitor TS10: Inhibition mechanism, metabolites identification and PDPK assessment.

Xanthine oxidase (XO) inhibitors are widely used in the control of serum uric acid levels in the clinical management of gout. Our continuous efforts in searching novel amide-based XO inhibitors culminated in the identification of N-(4-((3-cyanobenzyl)oxy)-3-(1H-tetrazol-1-yl)phenyl)isonicotinamide (TS10), which exhibited comparable in vitro inhibition to that of topiroxostat (TS10, IC50 = 0.031 µM; topiroxostat, IC50 = 0.020 µM). According to the molecular modeling, we speculated that, as well as topiroxostat, TS10 would be biotransformed by XO to yield TS10-2-OH. In this work, TS10-2-OH was successfully identified in XO targeted metabolism study, demonstrated that TS10 underwent a covalent binding with XO via a TS10-O-Mo intermediate after anchoring in the XO molybdenum cofactor pocket. Furthermore, TS10-2-OH is a weak active metabolite, and its potency was explained by the molecular docking. In metabolites identification, TS10 could be oxidized by CYP2C9, CYP3A4 and CYP3A5 to generate two mono-hydroxylated metabolites (not TS10-2-OH); and could occur degradation in plasma to mainly generate a hydrolytic metabolite (TS10-hydrolysate). In pharmacokinetic assessment, the low oral system exposure was observed (Cmax = 14.73 ± 2.66 ng/mL and AUClast = 9.17 ± 1.42 h⋅ng/mL), which could be explained by the poor oral absorption property found in excretion studies. Nonetheless, in pharmacodynamic evaluation, TS10 exhibited significant uric acid-lowering effect after oral administration in a dose-dependent manner. Briefly, in addition to allopurinol and topiroxostat, TS10 is possibly another explicitly mechanism-based XO inhibitor with powerful covalent inhibition.

Novel 4,5-dihydrospiro[benzo[c]azepine-1,1'-cyclohexan]-3(2H)-one derivatives as PARP-1 inhibitors: Design, synthesis and biological evaluation.

To further explore the research of novel PARP-1 inhibitors, we designed and synthesized a series of novel amide PARP-1 inhibitors based on our previous research. Most compounds displayed certain antitumor activities against four tumor cell lines (A549, HepG2, HCT-116, and MCF-7). Specifically, the candidate compound R8e possessed strong anti-proliferative potency toward A549 cells with the IC50 value of 2.01 µM. Compound R8e had low toxicity to lung cancer cell line. And the in vitro enzyme inhibitory activity of compound R8e was better than rucaparib. Molecular docking studies provided a rational binding model of compound R8e in complex with rucaparib. The following cell cycle and apoptosis assays revealed that compound R8e could arrest cell cycle in the S phase and induce cell apoptosis. Western blot analysis further showed that compound R8e could effectively inhibit the PAR's biosynthesis and was more effective than rucaparib. Overall, based on the biological activity evaluation, compound R8e could be a potential lead compound for further developing novel amide PARP-1 inhibitors.

2-((1-Phenyl-1H-1,2,3-triazol-4-yl)methyl)-2-azabicyclo[3.2.1]octan-3-one derivatives: Simplification and modification of aconitine scaffold for the discovery of novel anticancer agents.

The molecular chaperone heat shock protein 90 (Hsp90) is a promising target for cancer therapy. Natural product aconitine is a potential Hsp90 inhibitor reported in our previous work. In this study, we designed and synthesized a series of 2-((1-phenyl-1H-1,2,3-triazol-4-yl)methyl)-2-azabicyclo[3.2.1]octan-3-one derivatives as potent Hsp90 inhibitors by simplifying and modifying aconitine scaffold. Among these compounds, 14t exhibited an excellent antiproliferative activity against LoVo cells with an IC50 value of 0.02 µM and a significant Hsp90α inhibitory activity with an IC50 value of 0.71 nM. Molecular docking studies provided a rational binding model of 14t in complex with Hsp90α. The following cell cycle and apoptosis assays revealed that compound 14t could arrest cell cycle at G1/S phase and induce cell apoptosis via up-regulation of bax and cleaved-caspase 3 protein expressions while inhibiting the expressions of bcl-2. Moreover, 14t could inhibit cell migration in LoVo and SW620 cell lines. Consistent with in vitro results, 14t significantly repressed tumor growth in the SW620 xenograft mouse model.

Development of a novel thymidylate synthase (TS) inhibitor capable of up-regulating P53 expression and inhibiting angiogenesis in NSCLC.

INTRODUCTION: The development of a new type of Thymidylate synthase (TS) inhibitor that could inhibit cancer cells' proliferation and anti-angiogenesis is of great significance for cancer's clinical treatment. OBJECTIVES: Our research hopes to develop a TS inhibitor that is more effective than the current first-line clinical treatment of pemetrexed (PTX) and provide a new reference for the clinical treatment of non-small cell lung cancer (NSCLC). METHODS: We obtained a series of novel TS inhibitors by chemical synthesis. Moreover, TS assay and molecular docking to verify the target compound's inhibitory mode. Use MTT assay, colony-forming assay, flow cytometry, and western blot to verify the compound's inhibitory effect on cancer cell proliferation and its mechanism; and explore the compound's effect on angiogenesis in vitro and in vivo. Further, explore the hit compound's anti-cancer ability through the xenograft tumor model and the orthotopic cancer murine model. RESULTS: A series of N-(3-(5-phenyl-1,3,4-oxadiazole-2-yl) phenyl)-2,4-dihydroxypyrimidine-5-sulfamide derivatives were synthesized as TS inhibitors for the first time. All target compounds significantly inhibited hTS enzyme activity and demonstrated significant antitumor activity against five cancer cell lines. Notably, 7f had a high selectivity index (SI) and unique inhibitory effects on eight NSCLC cells. In-depth research indicated that 7f could induce apoptosis by the mitochondrial pathway in A549 and PC-9 cells through the upregulation of wild-type P53 protein expression. Additionally, 7f was shown to inhibit angiogenesis in vitro and in vivo. In vivo studies, compared to PTX, 7f significantly inhibited tumor growth in A549 cell xenografts and had a higher therapeutic index (TGI). Moreover, 7f could prolong the survival of the orthotopic lung cancer murine model more effectively than PTX. CONCLUSION: The anti-angiogenic effect of 7f provides a new reference for the development of TS inhibitors and the clinical treatment of NSCLC.

Identification of Novel Src Inhibitors: Pharmacophore-Based Virtual Screening, Molecular Docking and Molecular Dynamics Simulations.

Src plays a crucial role in many signaling pathways and contributes to a variety of cancers. Therefore, Src has long been considered an attractive drug target in oncology. However, the development of Src inhibitors with selectivity and novelty has been challenging. In the present study, pharmacophore-based virtual screening and molecular docking were carried out to identify potential Src inhibitors. A total of 891 molecules were obtained after pharmacophore-based virtual screening, and 10 molecules with high docking scores and strong interactions were selected as potential active molecules for further study. Absorption, distribution, metabolism, elimination and toxicity (ADMET) property evaluation was used to ascertain the drug-like properties of the obtained molecules. The proposed inhibitor-protein complexes were further subjected to molecular dynamics (MD) simulations involving root-mean-square deviation and root-mean-square fluctuation to explore the binding mode stability inside active pockets. Finally, two molecules (ZINC3214460 and ZINC1380384) were obtained as potential lead compounds against Src kinase. All these analyses provide a reference for the further development of novel Src inhibitors.

Design, synthesis and biological evaluation of erythrina derivatives bearing a 1,2,3-triazole moiety as PARP-1 inhibitors.

Inhibitors of poly (ADP-ribose) polymerase-1 (PARP-1) have shown to be promising in clinical trials against cancer, and many researchers are interested in the development of new PARP-1 inhibitors. Herein, we designed and synthesized 44 novel erythrina derivatives bearing a 1,2,3-triazole moiety as PARP-1 inhibitors. MTT assay results indicated that compound 10b had the most potent anti-proliferative activity against A549 cells among five cancer cells. The enzyme inhibitory activity in vitro of compound 10b was also significantly better than rucaparib. Furthermore, the selectivity index of compound 10b was higher than rucaparib for lung cancer cells. Flow cytometry analysis showed that compound 10b induced apoptosis of A549 cells by the mitochondrial pathway. Western blot analysis indicated that compound 10b was able to inhibit the biosynthesis of PAR effectively, and it was more potent than rucaparib. Also, compound 10b was able to up-regulate the ratio of bax/bcl-2, activate caspase-3, and ultimately induced apoptosis of A549 cells. The combined results revealed that the discovery of novel non-amide based PARP-1 inhibitors have great research significance and provide a better choice for the future development of drugs.

Design, synthesis and biological evaluation of homoerythrina alkaloid derivatives bearing a triazole moiety as PARP-1 inhibitors and as potential antitumor drugs.

A series of homoerythrina alkaloid derivatives containing a 1,2,3-triazole moiety as PARP-1 inhibitors were designed and synthesized. And their anti-proliferative activity was further evaluated. Compound 10n had excellent activity to inhibit proliferation of A549 cells (IC50 = 1.89 µM), which was higher than harringtonine (IC50 = 10.55 µM), pemetrexed (IC50 = 3.39 µM), and rucaparib (IC50 = 4.91 µM). Furthermore, the selectivity index of compound 10n was higher than rucaparib and pemetrexed for lung cancer cells. Flow cytometry analysis showed that compound 10n significantly arrested the cell cycle in the S phase, then induced apoptosis of A549 cells (apoptosis rate is 46%), which effectively inhibited cell proliferation. Simultaneously, western blot analysis revealed that compound 10n could prevent the biosynthesis of PAR. Further analysis results revealed that compound 10n could inhibit the expression of cyclin A, down-regulate the expression of bcl-2/bax, activate caspase-3, and ultimately induce apoptosis of A549 cells. All the results indicated that compound 10n had potential research value as a novel PARP-1 inhibitor in antitumor, and it provided a new reference for further development of PARP-1 inhibitors.

Discovery of N-phenyl-(2,4-dihydroxypyrimidine-5-sulfonamido) phenylurea-based thymidylate synthase (TS) inhibitor as a novel multi-effects antitumor drugs with minimal toxicity.

Thymidylate synthase (TS) is a hot target for tumor chemotherapy, and its inhibitors are an essential direction for anti-tumor drug research. To our knowledge, currently, there are no reported thymidylate synthase inhibitors that could inhibit cancer cell migration. Therefore, for optimal therapeutic purposes, combines our previous reports and findings, we hope to obtain a multi-effects inhibitor. This study according to the principle of flattening we designed and synthesized 18 of N-phenyl-(2,4-dihydroxypyrimidine-5-sulfonamido)phenyl urea derivatives as multi-effects inhibitors. The biological evaluation results showed that target compounds could significantly inhibit the hTS enzyme, BRaf kinase and EGFR kinase activity in vitro, and most of the compounds had excellent anti-cell viability for six cancer cell lines. Notably, the candidate compound L14e (IC50 = 0.67 µM) had the superior anti-cell viability and safety to A549 and H460 cells compared with pemetrexed. Further studies had shown that L14e could cause G1/S phase arrest then induce intrinsic apoptosis. Transwell, western blot, and tube formation results proved that L14e could inhibit the activation of the EGFR signaling pathway, then ultimately achieve the purpose of inhibiting cancer cell migration and angiogenesis in cancer tissues. Furthermore, in vivo pharmacology evaluations of L14e showed significant antitumor activity in A549 cells xenografts with minimal toxicity. All of these results demonstrated that the L14e has the potential for drug discovery as a multi-effects inhibitor and provides a new reference for clinical treatment of non-small cell lung cancer.

Design, synthesis and biological evaluation of N-phenyl-(2,4-dihydroxypyrimidine-5-sulfonamido)benzoyl hydrazide derivatives as thymidylate synthase (TS) inhibitors and as potential antitumor drugs.

The Inhibition of cellular nucleotide metabolism to promote apoptosis is a key principle of cancer therapy. Thymidylate synthase (TS) is a key rate-limiting enzyme in the initiation of DNA synthesis in cell. Here, we presented two types of thymidylate synthase inhibitors, and, the key pharmacological properties of these two types of thymidylate synthase inhibitor were extracted and combined to design new compounds with inhibitory activity. Therefore, two series of 42 new compounds with the common biological effect of promoting apoptosis are designed and synthesized by combination principle. Most of the compounds had good anti-proliferative activity on A549, OVCAR-3, SGC7901 and MDA-MB-231 cells. The IC50 of compound 10l on A549 cells was 1.26 µM, which was better than that of pemetrexed (PTX, IC50 = 3.31 µM), furthermore, the selection index of compound 10l was higher than PTX. Flow cytometry analysis showed that compound 10l (the apoptosis rate is 39.4%) could induce A549 cell apoptosis and effectively inhibit tumor cell proliferation. Further western blot analysis showed that compound 10l could induce intrinsic apoptosis by activating caspase-3, increasing expression of cleaved caspase-3 and reducing the ratio of bcl-2/bax. All of this makes compound 10l to be a promising compound in future animal tumor models.

Design, synthesis and anticancer activities evaluation of novel 5H-dibenzo[b,e]azepine-6,11-dione derivatives containing 1,3,4-oxadiazole units.

Rucaparib and PJ34 were used as the structural model for the design of novel 5H-dibenzo[b,e]azepine-6,11-dione derivatives containing 1,3,4-oxadiazole units. And target compounds were successfully synthesized through a 3-step synthetic strategy. All target compounds were screened for their anti-proliferative effects against OVCAR-3 cell line. Preliminary biological study of these compounds provided potent compounds d21 and d22 with better activities than Rucaparib.