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Small molecule-driven JNK activation has been found to induce apoptosis and paraptosis in cancer cells. Herein pharmacological effects of synthetic oxazine (4aS, 7aS)-3-((4-(4‑chloro-2-fluorophenyl)piperazin-1-yl)methyl)-4-phenyl-4, 4a, 5, 6, 7, 7a-hexahydrocyclopenta[e] [1,2]oxazine (FPPO; BSO-07) on JNK-driven apoptosis and paraptosis has been demonstrated in human breast cancer (BC) MDA-MB231 and MCF-7 cells respectively. BSO-07 imparted significant cytotoxicity in BC cells, induced activation of JNK, and increased intracellular reactive oxygen species (ROS) levels. It also enhanced the expression of apoptosis-associated proteins like PARP, Bax, and phosphorylated p53, while decreasing the levels of Bcl-2, Bcl-xL, and Survivin. Furthermore, the drug altered the expression of proteins linked to paraptosis, such as ATF4 and CHOP. Treatment with N-acetyl-cysteine (antioxidant) or SP600125 (JNK inhibitor) partly reversed the effects of BSO-07 on apoptosis and paraptosis. Advanced in silico bioinformatics, cheminformatics, density Fourier transform and molecular electrostatic potential analysis further demonstrated that BSO-07 induced apoptosis and paraptosis via the ROS/JNK pathway in human BC cells.

Abstract Aberrant activation of the PI3K/AKT signaling axis along with the sustained phosphorylation of downstream BAD is associated with a poor outcome of TNBC. Herein, the phosphorylated to non-phosphorylated ratio of BAD, an effector of PI3K/AKT promoting cell survival, was observed to be correlated with worse clinicopathologic indicators of outcome, including higher grade, higher proliferative index and lymph node metastasis. The structural optimization of a previously reported inhibitor of BAD-Ser99 phosphorylation was therefore achieved to generate a small molecule inhibiting the phosphorylation of BAD at Ser99 with enhanced potency and improved oral bioavailability. The molecule 2-((4-(2,3-dichlorophenyl)piperazin-1-yl)(pyridin-3-yl)methyl) phenol (NCK) displayed no toxicity at supra-therapeutic doses and was therefore assessed for utility in TNBC. NCK promoted apoptosis and G0/G1 cell cycle arrest of TNBC cell lines in vitro, concordant with gene expression analyses, and reduced in vivo xenograft growth and metastatic burden, demonstrating efficacy as a single agent. Additionally, combinatorial oncology compound library screening demonstrated that NCK synergized with tyrosine kinase inhibitors (TKIs), specifically OSI-930 or Crizotinib in reducing cell viability and promoting apoptosis of TNBC cells. The synergistic effects of NCK and TKIs were also observed in vivo with complete regression of a percentage of TNBC cell line derived xenografts and prevention of metastatic spread. In patient-derived TNBC xenograft models, NCK prolonged survival times of host animals, and in combination with TKIs generated superior survival outcomes to single agent treatment. Hence, this study provides proof of concept to further develop rational and mechanistic based therapeutic strategies to ameliorate the outcome of TNBC.

Metastasis, the dissemination of tumor cells, stands as the second most prominent contributor to mortality arising from breast cancer. To counteract this phenomenon, the molecular markers associated with angiogenesis, particularly vascular endothelial growth factor (VEGF) and its receptor (VEGFR), have emerged as promising strategies for impeding the progression of tumor cells. Compounds like pyrimidines, coumarins, oxadiazoles, and triazoles have undergone comprehensive investigations due to their notable anticancer potential, highlighting their encouraging capacities in inhibiting VEGFR-2, an essential mediator of angiogenesis signaling. Herein, we have synthesized pyrimidine–triazoles and oxadiazole–triazoles using electrochemical and conventional methods. The newly synthesized compounds were evaluated for anticancer activity against MCF-7 breast cancer cells, and it was found that the compounds 8a and 8b showed IC50 values of 5.29 and 15.54 μM, respectively. Our in silico mode of action revealed that these compounds could target VEGFR-2, which was further evidenced by our in silico structure-based bioinformatic analysis. In conclusion, we reported an electrochemical method to prepare novel drug-like compounds, based on triazole and other heterocyclic hybrids, that could be used to design VGFR-targeting drugs.

The development of environment-friendly new Poly-adenosine diphosphate (ADP)-ribose Polymerase (PARP) inhibitors are highly essential because of their involvement in the survival of cancer cells. Therefore, a library of indazolyl-substituted-1,3,4-oxadiazoles known to inhibit PARP in cancer cells was synthesized by a green protocol. Furthermore, the cytotoxic effects of these compounds were evaluated in human MCF-7 breast cancer (BC) cells, which revealed that the compound 2-(3-bromo-4-nitrophenyl)-5-(1-methyl-1H-indazol-3-yl)-1,3,4-oxadiazole (8) inhibited viability with an IC50 value of 1.57 µM. Since the oxadiazole structure was extensively used in medicinal chemistry applications, the reported environment-friendly protocol was superior to the conventional method. Further, computational mechanistic studies revealed that the oxadiazole ring formation occurred spontaneously when compared to the conventional method. Additionally, the in silico bioinformatic studies of oxadiazole binding towards PARP1 showed that compound 8 could bind to PARP1 with higher binding energy (BE) of −7.29 kcal/mol when compound to compound 5s (BE = −7.17 kcal/mol), a known PARP cleavage oxadiazole structure (2-(3,4-Dimethoxybenzyl)-5-(3-(2-fluoro-3-methylpyridin-4-yl)phenyl)-1,3,4-oxadiazole) indicative of the improvement in the optimization process. In conclusion, a newer indazolyl-oxadiazole compound is reported, which could serve as a lead in developing PARP inhibitors in BC cells.

Histone deacetylases (HDACs) are an attractive drug target for the treatment of human breast cancer (BC), and therefore, HDAC inhibitors (HDACis) are being used in preclinical and clinical studies. The need to understand the scope of the mode of action of HDACis, as well as the report of the co-crystal structure of HDAC6/SS-208 at the catalytic site, provoked us to develop an isoxazole-based lead structure called 4-(2-(((1-(3,4-dichlorophenyl)-1H-1,2,3-triazol-4-yl)methyl)thio) pyrimidin-4-yl) morpholine (5h) and 1-(2-(((3-(p-tolyl) isoxazol-5-yl)methyl)thio) pyrimidin-4-yl) piperidin-4-one (6l) that targets HDACs in human BC cells. We found that the compound 5h or 6l could inhibit the proliferation of BC cells with an IC50 value of 8.754 and 11.71 µM, respectively. Our detailed in silico analysis showed that 5h or 6l compounds could target HDAC in MCF-7 cells. In conclusion, we identified a new structure bearing triazole, isoxazole, and thiouracil moiety, which could target HDAC in MCF-7 cells and serve as a base to make new drugs against cancer.

Human epidermal growth factor receptor 2 (HER2)-positive breast cancer exhibits early relapses, poor prognoses, and high recurrence rates. Herein, a JNK-targeting compound has been developed that may be of utility in HER2-positive mammary carcinoma. The design of a pyrimidine-and coumarin-linked structure targeting JNK was explored and the lead structure PC-12 [4-(3-((2-((4-chlorobenzyl)thio) pyrimidin-4-yl)oxy)propoxy)-6-fluoro-2H-chromen-2-one (5d)] was observed to selectively inhibit the proliferation of HER2-positive BC cells. The compound PC-12 exerted DNA damage and induced apoptosis in HER-2 positive BC cells more significantly compared to HER-2 negative BC cells. PC-12 induced PARP cleavage and down-regulated the expression of IAP-1, BCL-2, SURVIVIN, and CYCLIN D1 in BC cells. In silico and theoretical calculations showed that PC-12 could interact with JNK, and in vitro studies demonstrated that it enhanced JNK phosphorylation through ROS generation. Overall, these findings will assist the discovery of new compounds targeting JNK for use in HER2-positive BC cells.