Diallyl trisulfide (DATS) is an attractive anti-cancer phytochemical with in vitro and in vivo growth inhibitory effects against different solid tumors including breast cancer. We have shown previously that an immortalized mammary epithelial cell line (MCF-10A) is resistant to growth inhibition by DATS. In this study, we performed RNA-seq analysis using a breast cancer cell line (SK-BR-3) and MCF-10A cells to gain insights into cancer selective effects of DATS. The Gene Ontology analysis revealed upregulation of genes associated with actin cytoskeleton but downregulation of mitochondria-related genes in the SK-BR-3 human breast cancer cell line but not in the non-oncogenic MCF-10A cell line upon treatment with DATS. Quantitative real-time reverse transcription polymerase chain reaction confirmed DATS-mediated upregulation of several actin cytoskeleton-related genes in the SK-BR-3 cell line. The DATS treatment dose-dependently disrupted actin cytoskeleton in the SK-BR-3 cell line, whereas the MCF-10A cell line was more resistant to this effect. The DATS treatment caused a marked increase in phosphorylation of dynamin-1-like (DRP1) protein in the SK-BR-3 cell line. However, the DATS-mediated apoptosis was not affected by genetic deletion of DRP1 protein. The Reactome pathway analysis showed downregulation of genes associated with citric acid cycle in the SK-BR-3 cell line but not in the MCF-10A cells. However, expression of aconitase 2 or dihydrolipoamide S-succinyltransferase was not affected by DATS treatment. In conclusion, this study reveals that actin cytoskeleton is a novel target of DATS in the SK-BR-3 cell line, which may explain its inhibitory effect on breast cancer cell migration.

Diallyl trisulfide (DATS), a metabolic by-product of processed garlic, is highly effective in inhibiting growth of human breast cancer cells in vitro and in vivo, but the underlying mechanisms are still not fully understood. In this study, we performed RNA-seq analyses using luminal-type (MCF-7) and basal-like (MDA-MB-231) human breast cancer cells to identify mechanistic targets of DATS. The Reactome Pathway Analysis revealed upregulation of genes associated with SLIT/ROBO tumor suppressor signaling following DATS treatment in both MCF-7 and MDA-MB-231 cells. However, the expression of SLIT2 and ROBO1 proteins or their downstream target C-X-C motif chemokine receptor 4 was not affected by DATS treatment in both cell lines. The Reactome as well as the Gene Ontology Pathways Analyses of the RNA-seq data from DATS-treated cells indicated downregulation of genes associated with G2 /M phase cell cycle arrest in comparison with vehicle-treated control cells. Consistent with the RNA-seq data, DATS treatment caused a significant increase in the fraction of the G2 /M population in both cell lines when compared to corresponding control cells. In addition, Ser10 phosphorylation of histone H3, a mitotic marker, was also increased significantly following DATS treatment in MCF-7 and MDA-MB-231 cells. These results indicate that while SLIT/ROBO signaling is not affected by DATS treatment, cell cycle arrest likely contributes to the antitumor effect of this phytochemical.

Diallyl trisulfide (DATS), a metabolic by-product of processed garlic, is highly effective in inhibiting growth of human breast cancer cells in vitro and in vivo, but the underlying mechanisms are still not fully understood. In this study, we performed RNA-seq analyses using luminal-type (MCF-7) and basal-like (MDA-MB-231) human breast cancer cells to identify mechanistic targets of DATS. The Reactome Pathway Analysis revealed upregulation of genes associated with SLIT/ROBO tumor suppressor signaling following DATS treatment in both MCF-7 and MDA-MB-231 cells. However, the expression of SLIT2 and ROBO1 proteins or their downstream target C-X-C motif chemokine receptor 4 was not affected by DATS treatment in both cell lines. The Reactome as well as the Gene Ontology Pathways Analyses of the RNA-seq data from DATS-treated cells indicated downregulation of genes associated with G2 /M phase cell cycle arrest in comparison with vehicle-treated control cells. Consistent with the RNA-seq data, DATS treatment caused a significant increase in the fraction of the G2 /M population in both cell lines when compared to corresponding control cells. In addition, Ser10 phosphorylation of histone H3, a mitotic marker, was also increased significantly following DATS treatment in MCF-7 and MDA-MB-231 cells. These results indicate that while SLIT/ROBO signaling is not affected by DATS treatment, cell cycle arrest likely contributes to the antitumor effect of this phytochemical.