3-(2-4-dichloro-5-methoxyphenyl)-2-sulfanyl-4(3h)-quinazolinone and Kidney-Neoplasms

Mitochondrial fragmentation occurs during the apoptosis. Dynamin-related protein 1 (Drp1) acts as an important component in mitochondrial fission machinery and can regulate various biological processes including apoptosis, cell cycle, and proliferation. The present study demonstrates that dysfunction of mitochondrial dynamics plays a pivotal role in cisplatin-induced apoptosis. Inhibiting the mitochondrial fission with the specific inhibitor (Mdivi-1) did not affect apoptotic cell death in low concentrations (<10 μM). Interestingly, mdivi-1 enhanced cisplatin-induced apoptosis in cancer cells, but not in normal cells. Particularly in the presence of mdivi-1, several human cancer cell lines, including renal carcinoma cell line Caki-1, became vulnerable to cisplatin by demonstrating the traits of caspase 3-dependent apoptosis. Combined treatment induced downregulation of c-FLIP expression transcriptionally, and ectopic expression of c-FLIP attenuated combined treatment-induced apoptotic cell death with mdivi-1 plus cisplatin. Collectively, our data provide evidence that mdivi-1 might be a cisplatin sensitizer.

Topics: Antineoplastic Agents; Apoptosis; CASP8 and FADD-Like Apoptosis Regulating Protein; Caspases; Cell Line, Tumor; Cisplatin; Drug Resistance, Neoplasm; Humans; Kidney Neoplasms; Quinazolinones; Transcription, Genetic

We previously reported that renal clear cell carcinoma cells (RCC) express both tumor necrosis factor receptor (TNFR)-1 and -2, but that, in organ culture, a TNF mutein that only engages TNFR1, but not TNFR2, causes extensive cell death. Some RCC died by apoptosis based on detection of cleaved caspase 3 in a minority TUNEL-positive cells but the mechanism of death in the remaining cells was unexplained. Here, we underpin the mechanism of TNFR1-induced cell death in the majority of TUNEL-positive RCC cells, and show that they die by necroptosis. Malignant cells in high-grade tumors displayed threefold to four fold higher expression of both receptor-interacting protein kinase (RIPK)1 and RIPK3 compared with non-tumor kidney tubular epithelium and low-grade tumors, but expression of both enzymes was induced in lower grade tumors in organ culture in response to TNFR1 stimulation. Furthermore, TNFR1 activation induced significant MLKL(Ser358) and Drp1(Ser616) phosphorylation, physical interactions in RCC between RIPK1-RIPK3 and RIPK3-phospho-MLKL(Ser358), and coincidence of phospho-MLKL(ser358) and phospho-Drp1(Ser616) at mitochondria in TUNEL-positive RCC. A caspase inhibitor only partially reduced the extent of cell death following TNFR1 engagement in RCC cells, whereas three inhibitors, each targeting a different step in the necroptotic pathway, were much more protective. Combined inhibition of caspases and necroptosis provided additive protection, implying that different subsets of cells respond differently to TNF-α, the majority dying by necroptosis. We conclude that most high-grade RCC cells express increased amounts of RIPK1 and RIPK3 and are poised to undergo necroptosis in response to TNFR1 signaling.

Topics: Acrylamides; Apoptosis; Carcinoma, Renal Cell; Epithelial Cells; Gene Expression Regulation, Neoplastic; Humans; In Situ Nick-End Labeling; Kidney Neoplasms; Kidney Tubules; Necrosis; Organ Culture Techniques; Quinazolinones; Receptor-Interacting Protein Serine-Threonine Kinases; Receptors, Tumor Necrosis Factor, Type I; RNA, Messenger; Signal Transduction; Sulfonamides; Tumor Necrosis Factor-alpha; Up-Regulation