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.

Compelling evidence ties heparanase, an endoglycosidase that cleaves heparan sulfate side (HS) chains of proteoglycans, with all steps of tumor development, including tumor initiation, angiogenesis, growth, metastasis, and chemoresistance. Moreover, heparanase levels correlate with shorter postoperative survival of cancer patients, encouraging the development of heparanase inhibitors as anti-cancer drugs. Heparanase-inhibiting heparin/heparan sulfate-mimicking compounds and neutralizing antibodies are highly effective in animal models of cancer progression, yet none of the compounds reached the stage of approval for clinical use. The present study focused on newly synthesized triazolo–thiadiazoles, of which compound 4-iodo-2-(3-(p-tolyl)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazol-6-yl)phenol (4-MMI) was identified as a potent inhibitor of heparanase enzymatic activity, cell invasion, experimental metastasis, and tumor growth in mouse models. To the best of our knowledge, this is the first report showing a marked decrease in primary tumor growth in mice treated with small molecules that inhibit heparanase enzymatic activity. This result encourages the optimization of 4-MMI for preclinical and clinical studies primarily in cancer but also other indications (i.e., colitis, pancreatitis, diabetic nephropathy, tissue fibrosis) involving heparanase, including viral infection and COVID-19.

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.

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.

Novel PARP inhibitors with selective mode-of-action have been approved for clinical use. Herein, oxadiazole based ligands that are predicted to target PARP-1 have been synthesized and screened for the loss of cell viability in mammary carcinoma cells, wherein seven compounds were observed to possess significant IC₅₀ values in the range of 1.4 to 25 µM. Furthermore, compound 5u, inhibited the viability of MCF-7 cells with an IC₅₀ value of 1.4µM, when compared to Olaparib (IC₅₀ = 3.2 µM). Compound 5s also decreased cell viability in MCF-7 and MDA-MB-231 cells with IC₅₀ values of 15.3 and 19.2 µM, respectively. Treatment of MCF-7 cells with compounds 5u and 5s produced PARP cleavage, H2AX phosphorylation and CASPASE-3 activation comparable to that observed with Olaparib. Compounds 5u and 5s also decreased foci-formation and 3D Matrigel growth of MCF-7 cells equivalent to or greater than that observed with Olaparib. Finally, in silico analysis demonstrated binding of compound 5s towardsthe catalytic site of PARP-1, indicating that these novel oxadiazoles synthesized herein may serve as exemplars for the development of new therapeutics in cancer.

Nuclear factor kappa B (NF–κB) is a potential therapeutic target in breast cancer. In the current study, a new class of oxazine– and piperazine–linked pyrimidines was developed as inhibitors of NF–κB, overcoming the complexity of the oxazine structure found in nature and enabling synthesis under laboratory conditions. Among the series of synthesized and tested oxazine–pyrimidine and piperazine–pyrimidine derivatives, compounds 3a and 5b inhibited breast cancer cell (MCF–7) viability with an IC₅₀ value of 9.17 and 6.29 µM, respectively. In silico docking studies showed that the pyrimidine ring of 3a and the 4–methoxybenzyl thiol group of 5b could strongly bind the p65 subunit of NF–κB, with the binding energies −9.32 and −7.32 kcal mol⁻¹. Furthermore, compounds 3a and 5b inhibited NF–κB in MCF–7 breast cancer cells. In conclusion, we herein report newer structures that target NF–κB in BC cells.