9-Ethynyl noscapine induces G2/M arrest and apoptosis by disrupting tubulin polymerization in cervical cancer

Synthesis and biological evaluation of novel 5-substituted/unsubstituted triazolothiadiazines as tubulin depolymerizing and vascular disrupting agents with promising antitumor activity

A novel series of 5-substituted/unsubstituted [1,2,4]triazolo[3,4-b][1,3,4] thiadiazine compounds has been achieved successfully through chemoselective reduction of the C = N bond, based on our prior work. Initial biological evaluation illustrated that the most active derivative 7j exhibited significant cell growth inhibitory activity toward MCF-7, A549, HCT116, and A2780 with the IC50 values of 0.75, 0.94, 2.90, and 4.15 μM, respectively. Most importantly, all the representative analogs did not demonstrate obvious cytotoxic activity against the non-tumoural cell line HEK-293 (IC50  > 100 μM). The mechanism study revealed that 7j caused the G2 /M phase arrest, induced cell apoptosis in HeLa cells in a concentration-dependent manner, and also showed potent tubulin polymerization inhibitory effect. Meanwhile, 7j exerted significant antivascular activity in the wound-healing and tube formation assays. These observations indicate that 5-unsubstituted 6,7-dihydro-5H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine scaffold might be considered as a potential lead for antitubulin inhibitors to develop highly efficient anticancer agents with potent selectivity over normal human cells.

Development of 9-(N-arylmethylamino) congeners of noscapine: the microtubule targeting drugs for the management of breast cancer

Noscapine is a natural lead molecule with anticancer activity at a higher concentrations. So, there is an urge for the development of more potent derivatives of noscapine. In this study, we have approached for development of 9-N-arylmethylamino derivatives of noscapine that kills cancer cells without affecting the normal cells. They were designed by substituting N-aryl methyl pharmacophore at the C-9 position and screened out top-ranked three derivatives 13a-c using molecular docking. Further, their theoretical free energy of binding with tubulin was calculated followed by chemical synthesis and experimental validation. In vitro antiproliferative activity of noscapine and its 9-N-arylmethylamino derivatives (13a-c) was carried out using MCF-7 (a triple receptors positive) and MDA-MB-231 (a triple receptor negative) breast cancer cell lines. Further, cytotoxicity to normal cells was examined using human embryonic kidney cells (HEK cells). Inhibition to cell cycle progression and induction of apoptosis was monitored using FACS. The binding of noscapine and 13a-c with tubulin was examined using fluorescence quenching assay. The 9-N-arylmethylamino derivatives of noscapine (13a-c) were found to inhibit the proliferation of cancer cells at a much lower concentration (IC50 values range between 9.1 to 47.3 µM) compared to noscapine (IC50 value is 45.8-59.3 µM). Surprisingly, the proliferation of HEK cells was not inhibited even at a concentration of 100 µM (cytotoxicity is < 5%). These derivatives induced apoptosis by arresting cells at G2/M-phase and also bind to tubulin. The 9-(N-arylmethylamino) noscapinoids have the potential to be a novel therapeutic agent for the treatment of breast cancer.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03445-3.

Noscapine-Amino Acid Conjugates Suppress the Progression of Cancer Cells

Lung cancer is the leading cause of cancer deaths globally; 1 in 16 people are diagnosed with lung cancer in their lifetime. Microtubules, a critical cytoskeletal assembly, have an essential role in cell division. Interference with the microtubule assembly leads to genetic instability during mitosis and cancer cell death. Currently, available antimitotic drugs such as vincas and taxanes are limited due to side effects such as alopecia, myelosuppression, and drug resistance. Noscapine, an opium alkaloid, is a tubulin-binding agent and can alter the microtubule assembly, causing cancer cell death. Amino acids are fundamental building blocks for protein synthesis, making them essential for the biosynthesis of cancer cells. However, the ability of amino acids in drug transportation has yet to be exploited in developing noscapine analogues as a potential drug candidate for cancer. Hence, in the present study, we have explored the ninth position of noscapine by introducing a hydroxymethylene group using the Blanc reaction and further coupled it with a series of amino acids to construct five target conjugates in good yields. The synthesized amino acid conjugate molecules were biologically evaluated against the A549 lung cancer cell line, among which the noscapine-tryptophan conjugate showed IC50 = 32 μM, as compared to noscapine alone (IC50 = 73 μM). Morphological changes in cancer cells, cell cycle arrest in the G1 phase, and ethidium bromide/acridine orange staining indicated promising anticancer properties. Molecular docking confirmed strong binding to tubulin, with a score of -41.47 kJ/mol with all 3D coordinates and significant involvement of molecular forces, including the hydrogen bonds and hydrophobic interactions. Molecular dynamics simulations demonstrated a stable binding of noscapine-tryptophan conjugate for a prolonged time (100 ns) with the involvement of free energy through the reaction coordinates analyses, solving the bioavailability of parent noscapine to the body.

Cytotoxic effect of disulfiram/copper on human cervical cancer cell lines and LGR5-positive cancer stem-like cells

BACKGROUND

Tumor resistance is a global challenge for tumor treatment. Cancer stem cells (CSCs) are the main population of tumor cells for drug resistance. We have reported that high aldehyde dehydrogenase (ALDH) activity represents a functional marker for cervical CSCs. Here, we aimed at disulfiram (DSF), an ALDH inhibitor, that has the potential to be used for cervical cancer treatment.

METHODS

MTT assay, western blot, vector construction and transfection, cell sorting and in vivo anti-tumor assays were performed using cervical cancer cell lines SiHa and HeLa. Cell cycle distribution and cell apoptosis were carried out by flow cytometry. The cytotoxicity of DSF was detected by MTT assay and cervical cancer xenograft models.

RESULTS

DSF was cytotoxic to cervical cancer cell lines in a copper (Cu)-dependent manner. Disulfiram/copper (DSF/Cu) complex induced deregulation of S-phase and inhibited the expression of stemness markers in cervical cancer cells. Furthermore, DSF/Cu could also reduce the cancer stem cell-like LGR5⁺ cells which lead to cisplatin resistance in cervical cancer cells. DSF/Cu complex had the greater antitumor efficacy on cervical cancer than cisplatin in vitro and in vivo.

CONCLUSION

Our findings indicate that the cytotoxicity of DSF/Cu complex may be superior to cisplatin because of targeting LGR5-positive cervical cancer stem-like cells in cervical cancer. Thus, the DSF/Cu complex may represent a potential therapeutic strategy for cervical cancer patients.