Blockade of CaV3 calcium channels and induction of G0/G1 cell cycle arrest in colon cancer cells by gossypol.

BACKGROUND AND PURPOSE: Gastrointestinal tumours overexpress voltage-gated calcium (CaV3) channels (CaV3.1, 3.2 and 3.3). CaV3 channels regulate cell growth and apoptosis colorectal cancer. Gossypol, a polyphenolic aldehyde found in the cotton plant, has anti-tumour properties and inhibits CaV3 currents. A systematic study was performed on gossypol blocking mechanism on CaV3 channels and its potential anticancer effects in colon cancer cells, which express CaV3 isoforms. EXPERIMENTAL APPROACH: Transcripts for CaV3 proteins were analysed in gastrointestinal cancers using public repositories and in human colorectal cancer cell lines HCT116, SW480 and SW620. The gossypol blocking mechanism on CaV3 channels was investigated by combining heterologous expression systems and patch-clamp experiments. The anti-tumoural properties of gossypol were estimated by cell proliferation, viability and cell cycle assays. Ca2+ dynamics were evaluated with cytosolic and endoplasmic reticulum (ER) Ca2+ indicators. KEY RESULTS: High levels of CaV3 transcripts correlate with poor prognosis in gastrointestinal cancers. Gossypol blockade of CaV3 isoforms is concentration- and use-dependent interacting with the closed, activated and inactivated conformations of CaV3 channels. Gossypol and CaV3 channels down-regulation inhibit colorectal cancer cell proliferation by arresting cell cycles at the G0/G1 and G2/M phases, respectively. CaV3 channels underlie the vectorial Ca2+ uptake by endoplasmic reticulum in colorectal cancer cells. CONCLUSION AND IMPLICATIONS: Gossypol differentially blocked CaV3 channel and its anticancer activity was correlated with high levels of CaV3.1 and CaV3.2 in colorectal cancer cells. The CaV3 regulates cell proliferation and Ca2+ dynamics in colorectal cancer cells. Understanding this blocking mechanism maybe improve cancer therapies.

Influence of gossypol acetic acid on the growth of human adenoid cystic carcinoma ACC-M cells and the expression of DNA methyltransferase 1.

We investigated the effects of gossypol acetic acid (GAA) on the proliferation, apoptosis, and expression of DNA methyltransferase 1 (DNMT1) mRNA in human adenoid cystic carcinoma (ACC-M) cells in vitro. The proliferation and apoptosis of ACC-M cells after treatment with different concentrations of GAA were detected using Cell Counting Kit-8 and flow cytometry, respectively. DNMT1 mRNA expression was measured by real-time fluorescence quantitative polymerase chain reaction. The growth of ACC-M cells was inhibited after treatment with GAA for 24, 48, and 72 h. The apoptotic rates of ACC-M cells after treatment with GAA for 72 h were higher than those of control cells (without treatment) (P < 0.05). DNMT1 mRNA expression in ACC-M after treatment with GAA for 72 h was lower than that in control cells (P < 0.05). GAA had inhibitory effects on the proliferation and induced apoptosis of human ACC-M cells, while GAA also reduced the expression level of DNMT1 mRNA in ACC-M cells.

Small-molecule BH3 mimetic and pan-Bcl-2 inhibitor AT-101 enhances the antitumor efficacy of cisplatin through inhibition of APE1 repair and redox activity in non-small-cell lung cancer.

AT-101 is a BH3 mimetic and pan-Bcl-2 inhibitor that has shown potent anticancer activity in non-small-cell lung cancer (NSCLC) in murine models, but failed to show clinical efficacy when used in combination with docetaxel in NSCLC patients. Our recent study has demonstrated that AT-101 enhanced the antitumor effect of cisplatin (CDDP) in a murine model of NSCLC via inhibition of the interleukin-6/signal transducer and activator of transcription 3 (STAT3) pathway. This study explored the underlying mechanisms for the enhanced anticancer activity of CDDP by AT-101. Our results show that, when compared with monotherapy, AT-101 significantly enhanced the inhibitory effects of CDDP on proliferation and migration of A549 cells and on tube formation and migration in human umbilical vein endothelial cells. AT-101 promoted the proapoptotic activity of CDDP in A549 cells. AT-101 also enhanced the inhibitory effect of CDDP on DNA repair and redox activities of apurinic/apyrimidinic endonuclease 1 (APE1) in A549 cells. In tumor tissues from nude mice treated with AT-101 plus CDDP or monotherapy, the combination therapy resulted in greater inhibition of angiogenesis and tumor cell proliferation than the monotherapy. These results suggest that AT-101 can enhance the antitumor activity of CDDP in NSCLC via inhibition of APE1 DNA repair and redox activities and by angiogenesis and induction of apoptosis, but other mechanisms cannot be excluded. We are now conducting a Phase II trial to examine the clinical efficacy and safety profile of combined use of AT-101 plus CDDP in advanced NSCLC patients.

Effects of gossypol on mice infected with Trypanosoma cruzi

Ratones albinos suizos adultos, inoculados intraperitonealmente con 1 000 ó 5 000 tripomastigotes (Trypanosoma cruzi, cepa Tulahuén), fueron tratados con gossypol-ácido acético diariamente, por vía oral, con dosis de 10 mg/kg/día, comenzando el día de la inoculación o 10 días antes y continuando hasta la muerte de los animales. Los niveles de parasitemia y el tiempo de sobrevida no fueron modificados por el tratamiento. Ratones inoculados con 100 tripomastigotes recibieron, por vía oral, 10 mg/kg/día de gossypolácido acético desde el día de la infección (grupo 1), o desde 30 días antes (grupo 2), hasta el 100§ día post-inoculación. Los animales de ambos grupos tratados mostraron niveles de parasitemia más bajos que los controles. La mortalidad, a los 24 días post-infección, fue significativamente más baja en ratones del grupo 2 que en los controles. En la casi totalidad de los animales tratados se observaban tripomastigotes circulantes al final del tratamiento. Se concluye que el glossypol, a la dosis de 10 mg/kg/día, tiene cierta acción favorable en ratones infectados con 100 tripomastigotes, disminuyendo la parasitemia y la tasa de mortalidad, pero no los cura ni previene la infección. Sangre total de ratones infectados fue adicionada con gossypol-ácido acético a concentraciones finales 5 micronM y 10 micronM y conservada durante 5 días en las condiciones habituales en bancos de sangre. Hubo reducción del número de tripomastigotes, per los parásitos remanentes conservaban su...

Effects of gossypol on mice infected with Trypanosoma cruzi

Ratones albinos suizos adultos, inoculados intraperitonealmente con 1 000 ó 5 000 tripomastigotes (Trypanosoma cruzi, cepa Tulahuén), fueron tratados con gossypol-ácido acético diariamente, por vía oral, con dosis de 10 mg/kg/día, comenzando el día de la inoculación o 10 días antes y continuando hasta la muerte de los animales. Los niveles de parasitemia y el tiempo de sobrevida no fueron modificados por el tratamiento. Ratones inoculados con 100 tripomastigotes recibieron, por vía oral, 10 mg/kg/día de gossypolácido acético desde el día de la infección (grupo 1), o desde 30 días antes (grupo 2), hasta el 100º día post-inoculación. Los animales de ambos grupos tratados mostraron niveles de parasitemia más bajos que los controles. La mortalidad, a los 24 días post-infección, fue significativamente más baja en ratones del grupo 2 que en los controles. En la casi totalidad de los animales tratados se observaban tripomastigotes circulantes al final del tratamiento. Se concluye que el glossypol, a la dosis de 10 mg/kg/día, tiene cierta acción favorable en ratones infectados con 100 tripomastigotes, disminuyendo la parasitemia y la tasa de mortalidad, pero no los cura ni previene la infección. Sangre total de ratones infectados fue adicionada con gossypol-ácido acético a concentraciones finales 5 micronM y 10 micronM y conservada durante 5 días en las condiciones habituales en bancos de sangre. Hubo reducción del número de tripomastigotes, per los parásitos remanentes conservaban su... (AU)