Design, synthesis and biological evaluation of new RNF126-based p300/CBP degraders.

Histone acetyltransferase CREB-binding protein (CBP) and its homologous protein p300 are key transcriptional activators that can activate oncogene transcription, which present promising targets for cancer therapy. Here, we designed and synthesized a series of p300/CBP targeted low molecular weight PROTACs by assembling the covalent ligand of RNF126 E3 ubiquitin ligase and the bromodomain ligand of the p300/CBP. The optimal molecule A8 could effectively degrade p300 and CBP through the ubiquitin-proteasome system in time- and concentration-dependent manners, with half-maximal degradation (DC50) concentrations of 208.35/454.35 nM and 82.24/79.45 nM for p300/CBP in MV4-11 and Molm13 cell lines after 72 h of treatment. And the degradation of p300/CBP by A8 is dependent on the ubiquitin-proteasome pathway and its simultaneous interactions with the target proteins and RNF126. A8 exhibits good antiproliferative activity in a series of p300/CBP-dependent cancer cells. It could transcriptionally inhibit the expression of c-Myc, induce cell cycle arrest in the G0/G1 phase and apoptosis in MV4-11 cells. This study thus provided us a new chemotype for the development of drug-like PROTACs targeting p300/CBP, which is expected to be applied in cancer therapy.

Design, synthesis and structure-activity relationship study of piperazinone-containing thieno[3,2-d]pyrimidine derivatives as new PI3Kδ inhibitors.

Two classes of piperazinone-containing thieno[3,2-d]pyrimidines were designed and synthesized as new PI3Kδ inhibitors in this study. Detailed SAR study with respect to the piperazinone substituents at the 6-position of thieno[3,2-d]pyrimidine core demonstrated that piperazinone-containing thieno[3,2-d]pyrimidines would be more potent and selective for PI3Kδ than their piperazine counterparts, which led to the discovery of several potent PI3Kδ inhibitors with comparable or better antiproliferative activity against a panel of non-Hodgkin lymphoma (NHL) cell lines as compared with idelalisib. Our study will promote the development of new PI3Kδ inhibitors based on piperazinone-containing thieno[3,2-d]pyrimidine scaffold.

Identification of a potent and selective phosphatidylinositol 3-kinase δ inhibitor for the treatment of non-Hodgkin's lymphoma.

PI3Kδ has proved to be an effective target for anti-lymphoma drugs. However, the application of current approved PI3Kδ inhibitors has been greatly limited due to their specific immune-mediated toxicity and increased risk of infection, it is necessary to develop more PI3Kδ inhibitors with new scaffold. In this study, SAR study with respect to piperazinone-containing purine derivatives led to the discovery of a potent and selective PI3Kδ inhibitor, 4-(cyclobutanecarbonyl)-1-((2-(2-ethyl-1H-benzo[d]imidazol-1-yl)-9-methyl-6-morpholino-9H-purin-8-yl)methyl)piperazin-2-one (WNY1613). WNY1613 exhibits good antiproliferative activity against a panel of non-Hodgkin's lymphoma (NHL) cell lines by inducing cancer cell apoptosis and inhibiting the phosphorylation of PI3K and MAPK downstream components. In addition, it can also prevent the tumor growth in both SU-DHL-6 and JEKO-1 xenograft models without observable toxicity. WNY1613 thus could be developed as a promising candidate for the treatment of NHL after subsequent extensive pharmacodynamics and pharmacokinetics investigation.

Synthesis and antitubercular evaluation of 4-carbonyl piperazine substituted 1,3-benzothiazin-4-one derivatives.

Tuberculosis (TB) remains a major human health problem. New therapeutic antitubercular agents are urgent needed to control the global tuberculosis pandemic. We synthesized a new series of 4-carbonyl piperazine substituted 1,3-benzothiazin-4-one derivatives and evaluated their anti-mycobacterial activities against Mycobacterium tuberculosis H37Ra as well as their druggabilities. The results showed that most of these derivatives, especially the compounds with simple alkyl side chains, exhibited good antitubercular activities and favorable aqueous solubilities with no obvious cytotoxicity. It suggested that the 4-carbonyl piperazine substituents in benzothiazinone scaffold were well tolerated, in which the compound 8h, with an antitubercular activity of MIC 0.008 µM, exhibited an excellent aqueous solubility of 104 µg/mL, which was 100-fold better than the potent DprE1 inhibitor Comp.1 (BTZ038), also more soluble than PBTZ169.

Reductions in myeloid-derived suppressor cells and lung metastases using AZD4547 treatment of a metastatic murine breast tumor model.

BACKGROUND: AZD4547, a small-molecule inhibitor targeting the tyrosine kinase of Fibroblast Growth Factor Receptors (FGFRs), is currently under phase II clinical study for human subjects having breast cancer, while the underlying mechanism remains elusive. The aim of this study is to explore the potential mechanism by which AZD4547 inhibits breast tumor lung metastases at the level of the tumor microenvironment. METHODS: First, through in vitro experiments, we investigated the efficacy of the FGFRs inhibitor AZD4547 on 4T1 tumor cells for their proliferation, apoptosis, migration, and invasion. Second, by in vivo animal experiments, we evaluated the effects of AZD4547 on tumor growth and lung metastases in 4T1 tumor-bearing mice. Finally, we examined the impact of AZD4547 on the infiltration of myeloid-derived suppressor cells (MDSCs) in lung, spleens, peripheral blood and tumor. RESULTS: Through this study we found that AZD4547 could efficiently suppress tumor 4T1 cells through restraining their proliferation, blocking migration and invasion, and inducing apoptosis in vitro. In animal model we also demonstrated that AZD4547 was able to inhibit tumor growth and lung metastases, consistent with the decreased MDSCs accumulation in the tumor and lung tissues, respectively. Moreover, the reduced number of MDSCs in peripheral blood and spleens were also observed in the AZD4547-treated mice. Importantly, through the AZD4547 treatment, the CD4(+) and CD8(+) T-cells were significantly increased in tumor and spleens. CONCLUSION: Our studies showed that AZD4547 can inhibit breast cancer cell proliferation, induce its apoptosis and block migration and invasion in vitro and suppress tumor growth and lung metastases by modulating the tumor immunologic microenvironment in vivo.

Design, synthesis, and biological evaluation of 4,5-dihydro-[1,2,4]triazolo[4,3-f]pteridine derivatives as novel dual-PLK1/BRD4 inhibitors.

Protein kinase inhibitors and epigenetic regulatory molecules are two main kinds of anticancer drugs developed in recent years. Both kinds of drugs harbor their own advantages and disadvantages in the treatment of cancer, and the development of small molecules which could target at kinases and epigenetic targets simultaneously can avoid the defects of drugs which only targets at kinases or epigenetic proteins. In this study, a series of 4,5-dihydro-[1,2,4]triazolo [4,3-f]pteridine derivatives were designed and synthesized based on the structure of PLK1 inhibitor BI-2536. Subsequent targets affinity screen and antiproliferative activity test led to the discovery of the most potent dual PLK1/BRD4 inhibitor 9b with good potency for both PLK1 (IC50 = 22 nM) and BRD4 (IC50 = 109 nM) as well as favorable antiproliferative activity against a panel of cancer cell lines. 9b could induce cell cycle arrest and apoptosis in acute myeloid leukemia cell line MV 4-11 in a concentration dependent manner. It could also downregulate the transcription of several proliferation-related oncogenes, including c-MYC, MYCN and BCL-2. Finally, in a MV4-11 mouse xenograft model, 9b exhibited favorable in vivo antitumor activity with 66% tumor growth inhibition (TGI) at a dose of 60 mg/kg while without obvious toxicity. This study thus provided us a start point for the development of new dual PLK1/BRD4 inhibitors as anticancer agents.

Correction: Inhibition of Stat3 signaling pathway by nifuroxazide improves antitumor immunity and impairs colorectal carcinoma metastasis.

Since publication of this article, the authors have noticed that there were errors in Fig. 1b (the CT 26 cells colony formation images) and Fig. 7c (the vehicle group images). As a result of the misfiling of the data during preparation of figures, incorrect images were inadvertently inserted in these figures.An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Inhibition of Stat3 signaling pathway by nifuroxazide improves antitumor immunity and impairs colorectal carcinoma metastasis.

Colorectal carcinoma (CRC) is the one of the most common cancers with considerable metastatic potential, explaining the need for new drug candidates that inhibit tumor metastasis. The signal transducers and activators of the transcription 3 (Stat3) signaling pathway has an important role in CRC and has been validated as a promising anticancer target for CRC therapy. In the present study, we report our findings on nifuroxazide, an antidiarrheal agent identified as an inhibitor of Stat3. Our studies showed that nifuroxazide decreased the viability of three CRC cell lines and induced apoptosis of cancer cells in a concentration-dependent manner. Moreover, western blot analysis demonstrated that the occurrence of its apoptosis was correlated with the activation of Bax and cleaved caspase-3, and decreased the expression of Bcl-2. In addition, nifuroxazide markedly impaired CRC cell migration and invasion by downregulating phosphorylated-Stat3Tyr705, and also impaired the expression of matrix metalloproteinases (MMP-2 and MMP-9). Furthermore, our studies showed that nifuroxazide also significantly inhibited the tumor metastasis in lung and abdomen metastasis models of colon cancer. Meanwhile, nifuroxazide functionally reduced the proliferation index, induced tumor apoptosis and impaired metastasis. Notably, nifuroxazide reduced the number of myeloid-derived suppressor cells in the blood, spleens and tumors, accompanied by the increased infiltration of CD8+ T cells in the tumors. Importantly, a marked decrease in the number of M2-type macrophages in tumor in the abdomen metastasis model was also observed. Taken together, our results indicated that nifuroxazide could effectively inhibit tumor metastasis by mediating Stat3 pathway and it might have a therapeutic potential for the treatment of CRC.