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A study was conducted to analyze a novel synthesis of trans-1,2-diiodoalkenes and their stereospecific and highly regioselective trifluoromethylation. The iodination of alkynes were carried out by adding a mixture of acetonitrile, alkyne and CuI in a flask. Results indicated the possibility of replacing the iodo substituent at the terminal position during the substitution of diiodoalkene by an aryl or carboethoxy group.

Molecular dynamics simulations are carried out investigate the influence of [Zn.sup.2+] on the p53 DNA recognition and the stability of the DNA-binding domain (DBD). The results suggest that loop L2 may be a frustrated and highly flexible element and play an important role in aggregation of Zn-free p53, and [Zn.sup.2+] keeps the L2 structured and probably prevents aggregation.

Zinc ions are frequently found in DNA-binding proteins. p53 is a cancer-related transcriptional factor, and its DNA-binding domain (DBD) contains a Zn2+, which has been shown to be important for aggregation and sequence-specific DNA binding. We have carried out molecular dynamics simulations to investigate the influence of Zn2+ on the p53 DNA recognition and the stability of the DBD. In the simulation with Zn2+ present, the protein attracted to the DNA phosphate backbone, allowing for Arg248 on loop L3 to be inserted into the minor groove for specific contact with the DNA base. The insertion of Arg248 between the backbone phosphate groups in the minor groove caused a narrowing of the minor groove, which is not seen in the simulation without Zn2+. Structurally, the zinc ion coordinated the motions among the different protein structural elements, which could also be important for optimal binding and core packing. The influence of Zn2+ on protein stability was mainly localized to the L2 loop. Our results suggest that L2 may be a frustrated and highly flexible element and play an important role in aggregation of Zn-free p53. Zn2+ keeps the L2 structured and probably prevents aggregation. [ABSTRACT FROM AUTHOR]

AST-3424 is a novel and highly tumor-selective prodrug. AST-3424 is activated by AKR1C3 to release a toxic bis-alkylating moiety, AST 2660. In this study, we have investigated the essential role of DNA repair in AST-3424 mediated pharmacological activities in vitro and in vivo. We show here that AST-3424 is effective as a single therapeutic agent against cancer cells to induce cytotoxicity, DNA damage, apoptosis and cell cycle arrest at G2 phase in a dose- and AKR1C3-dependent manner in both p53-proficient H460 (RRID:CVCL_0459) and p53-deficient HT-29 cells (RRID:CVCL_0320). The combination of abrogators of G2 checkpoint with AST-3424 was only synergistic in HT-29 but not in H460 cells. The enhanced activity of AST-3424 in HT-29 cells was due to impaired DNA repair ability via the attenuation of cell cycle G2 arrest and reduced RAD51 expression. Furthermore, we utilized a BRCA2 deficient cell line and two PDX models with BRCA deleterious mutations to study the increased activity of AST-3424. The results showed that AST-3424 exhibited enhanced in vitro cytotoxicity and superior and durable in vivo anti-tumor effects in cells deficient of DNA repair protein BRCA2. In summary, we report here that when DNA repair capacity is reduced, the in vitro and in vivo activity of AST-3424 can be further enhanced, thus providing supporting evidence for the further evaluation of AST-3424 in the clinic., (© 2024 The Author(s). International Journal of Cancer published by John Wiley & Sons Ltd on behalf of UICC.)

AST-3424/OBI-3424 (denoted by 3424) is a novel prodrug bis-alkylating agent activated by AKR1C3. AKR1C3 is overexpressed in many types of cancer, particularly in liver, non-small cell lung, gastric, renal and CRPC cancer. Currently 3424 is being studied in phase 1/2 clinical trials for the treatment of solid and hematologic cancers, and it represents potentially a novel, selective anti-cancer agent for multiple indications. In this study, AKR1C3-dependent activation of 3424 was investigated in vitro using recombinant human AKR1C3. AKR1C3-dependent cytotoxicity of 3424 was determined in a wide range of human cancer cell lines with different AKR1C3 expression levels. In addition, anti-tumor activity of 3424 was also investigated in a broad panel of CDX and PDX models. AKR1C3-dependent activation of prodrug 3424 was evident by monitoring the decrease of 3424 and generation of the active form, 2660. Kinetic analysis indicated that AKR1C3 exhibited higher catalytic efficiency towards 3424 compared to the physiological substrates. There was a strong correlation between 3424 cytotoxic potency and AKR1C3 expression. The racemic mixture induced DNA cross-linking in a concentration dependent manner. Tumor growth inhibition of 3424 was shown to be better than or comparable to the standard of care chemotherapy at clinically achievable doses as a single agent in various CDX models with high expression of AKR1C3, including liver HepG2, lung H460, castration-resistant prostate VCaP, gastric SNU-16, and kidney A498 cancer cell lines. The excellent anti-tumor efficacy of 3424 was further demonstrated in PDX models which have high level of AKR1C3 expression, but not in a model with low level of AKR1C3 expression. In the combination therapy, we showed that 3424 could enhance the efficacy of the standard care of chemotherapy in the CDX models. The results described here highlight that 3424 exhibits AKR1C3-dependent cytotoxicity in vitro and anti-tumor activity in vivo in a wide range of human cancer types, which support further development of 3424 as an anti-cancer agent for treating different types of cancers and the use of AKR1C3 as a biomarker to profile cancer patients and further guide patient selection for therapy with 3424., Competing Interests: All authors are current employees paid by either Ascentawits Pharmaceuticals, LTD or OBI Pharma, Inc., (AJCR Copyright © 2021.)