Cytotoxicity, tyrosine kinase inhibition of novel pyran, pyridine, thiophene, and imidazole derivatives

Revisiting VEGF/VEGFR-2 signalling as an anticancer target and its inhibitor discovery: where are we and where should we go?

Angiogenesis plays an important role in tumour growth and metastasis. Targeting tumour vascular endothelial cells to inhibit tumour angiogenesis and thus block tumour blood and nutrition supply is the current research focus on anti-tumour growth and metastasis. Vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor 2 (VEGFR-2) signal pathway regulates the proliferation, migration, survival and angiogenesis of vascular endothelial cells, which is abnormally activated in different tumours. Studies have confirmed that inhibiting VEGF/VEGFR-2 signalling pathway can produce anti-tumour effect. Nowadays, anti-angiogenesis therapy targeting VEGF/VEGFR-2 inhibition has become the most effective clinical strategy for cancer treatment. Therefore, a variety of VEGF/VEGFR-2 inhibitors with different structures have been developed. A few selectively inhibit VEGF to block the activation of VEGFR-2 pathway, while the majority selectively inhibit VEGFR-2 as multi-target inhibitors. Based on the classification of dominant skeletons, this paper briefly analyzes the biological activity, clinical research process and structure-activity relationship of the representative small molecule inhibitors of VEGF/VEGFR-2.

Synthesis and Biological Evaluation of Novel 2-imino-4-thiazolidinones as Potential Antitumor Agents for Glioblastoma

AIMS

The purpose of our study was to explore the molecular hybridization between 2-imino-4-thizolidione and piridinic scaffolds and its potential antitumor activity.

BACKGROUND

Glioblastoma is the most aggressive glioma tumor clinically diagnosed malignant and highly recurrent primary brain tumor type. The standard of treatment for a glioblastoma is surgery, followed by radiation and chemotherapy using temozolomide. However, the chemoresistance has become the main barrier to treatment success. 2-imino-4-thiazolidinones are an important class of heterocyclic compounds that feature anticancer activity; however the antiglioblastoma activity is yet to be explored.

OBJECTIVE

To synthesize and characterize a series of novel 2-imino-4-thiazolidinones and evaluate their antiglioblastoma activity.

METHOD

The 2-imino-4-thiazolidinone (5a-p) was synthesized according to the literature with modifications. Compounds were identified and characterized using spectroscopic analysis and X-ray diffraction. The antitumor activity was analyzed by 3-(4,5- dimethyl)-2,5-diphenyltetrazolium bromide (MTT) assay both in primary astrocyte and glioma (C6). Apoptosis and cell cycle phase were determined by flow cytometry analysis. The expression of caspase-3/7 was measured by luminescence assay. Oxidative stress parameters as: determination of reactive oxygen species (ROS), superoxide dismutase (SOD) activity, catalase (CAT) activity and total sulfhydryl content quantification were analyzed by colorimetric assays according to literature.

RESULTS

Among sixteen synthesized compounds, three displayed potent antitumor activities against tested glioblastoma cell line showed IC50 values well below the standard drug temozolomide. Therefore, compounds 5a, 5l and 5p were evaluated using cell cycle and death analysis, due to potent toxicity (2.17±1.17, 6.24±0.59, 2.93±1.12µM, respectively) in C6 cell line. The mechanism of action studies demonstrated that 5a and 5l induced apoptosis significantly increase the percentage of cells in Sub-G1 phase in the absence of necrosis. Consistent with these results, caspase-3/7 assay revealed that 5l presents pro-apoptotic activity due to the significant stimulation of caspases-3/7. Moreover, 5a, 5l and 5p increased antioxidant defense and decreased reactive oxygen species (ROS) production.

CONCLUSION

The compounds were synthesized with good yield and three of these presented (5a, 5l and 5p) good cytotoxicity against C6 cell line. Both affected cell cycle distribution via arresting more C6 cell line at Sub-G1 phase promoting apoptosis. Furthermore, 5a, 5l and 5p modulated redox status. These findings suggest that these compounds can be considered as promising lead molecules for further development of potential antitumor agents.