RNA-Seq transcriptome analysis shows anti-tumor actions of melatonin in a breast cancer xenograft model.

Melatonin is a pleiotropic anti-cancer molecule that controls cancer growth by multiple mechanisms. RNA-Seq can potentially evaluate therapeutic response and its use in xenograft tumor models can differentiate the changes that occur specifically in tumor cells or in the tumor microenvironment (TME). Melatonin actions were evaluated in a xenograft model of triple-negative breast cancer. Balb/c nude mice bearing MDA-MB-231 tumors were treated with melatonin or vehicle. RNA-Seq was performed on the Illumina HiSeq. 2500 and data were mapped against human and mouse genomes separately to differentiate species-specific expression. Differentially expressed (DE) genes were identified and Weighted Gene Co-expression Network Analysis (WGCNA) was used to detect clusters of highly co-expressed genes. Melatonin treatment reduced tumor growth (p < 0.01). 57 DE genes were identified in murine cells, which represented the TME, and were mainly involved in immune response. The WGCNA detected co-expressed genes in tumor cells and TME, which were related to the immune system among other biological processes. The upregulation of two genes (Tnfaip8l2 and Il1f6) by melatonin was validated in the TME, these genes play important roles in the immune system. Taken together, the transcriptomic data suggests that melatonin anti-tumor actions occur through modulation of TME in this xenograft tumor model.

Evaluation of Angiogenesis Process after Metformin and LY294002 Treatment in Mammary Tumor.

BACKGROUND: The angiogenesis process is regulated by many factors, such as Hypoxia-Inducible Factor-1 (HIF-1) and Vascular Endothelial Growth Factor (VEGF). Metformin has demonstrated its ability to inhibit cell growth and the LY294002 is the major inhibitor of PI3K/AKT/mTOR pathway that has antiangiogenic properties. METHODS: Canine mammary tumor cell lines CMT-U229 and CF41 were treated with metformin and LY294002. Cell viability, protein and gene expression of VEGF and HIF-1 were determined in vitro. For the in vivo study, CF41 cells were inoculated in female athymic nude mice treated with either metformin or LY294002. The microvessel density by immunohistochemistry for CD31 as well as the gene and protein expression of HIF-1 and VEGF were evaluated. RESULTS: The treatment with metformin and LY294002 was able to reduce the cellular viability after 24 hours. The protein and gene expression of HIF-1 and VEGF decreased after treatment with metformin and LY294002. In the in vivo study, there was a decrease in tumor size, protein and gene expression of HIF-1 and VEGFA, in addition to the decreasing of CD31 expression after all treatments. CONCLUSION: Our results demonstrate the effectiveness of metformin and LY294002 in controlling the angiogenesis process in mammary tumors by VEGF and HIF-1, the most important angiogenic markers.

Melatonin Differentially Modulates NF-кB Expression in Breast and Liver Cancer Cells.

BACKGROUND: NF-kB (nuclear factor kappa B) is a transcription factor composed of two subunits, p50 and p65, which plays a key role in the inflammatory process. Melatonin has oncostatic, antiangiogenic and antimetastatic properties, and some recent studies have indicated an inhibitory effect of melatonin on NF-kB in some types of cancer. This work aims to investigate the effects of melatonin treatment on the expression of NFkB in breast and liver cancer models. METHOD: The breast cancer xenographic model was performed using female Balb/c nude athymic mice injected with MDA-MB-231 cells. The animals were treated with 40 mg/Kg of melatonin for 21 days. Volume of the tumors was measured with a digital caliper. Hepatocarcinoma model was developed by using the HepG2 cells in vitro, treated with 1 mM melatonin for 24 h. The expression of NF-kB protein was verified by immunohistochemistry and immunocytochemistry and quantified by optical densitometry, in vivo study and in vitro study, respectively. NF-kB gene expression was performed by quantitative RT-PCR. RESULTS: The breast cancer xenografts nude mice treated with melatonin showed reduced tumor size (P=0.0022). There was a decrease in NF-kB protein staining (P=0.0027) and gene expression (P=0.0185) in mice treated with melatonin. The opposite results were observed for the hepatocarcinoma model. HepG2 cells treated with melatonin showed an increase in the NF-kB immunostaining when compared to control cells (P=0.0042). CONCLUSION: Our results indicated that the treatment with melatonin was able to decrease both gene and protein expressions of NF-kB in breast cancer cells and, conversely, increase the transcription factor protein expression in hepatocarcinoma cells. These data highlighted a double role in the expression of NF-kB, depending on the cell type. Further studies are needed to better elucidate the action of melatonin in NF-kB, since this transcription factor acts on different signaling pathways that are fundamental for carcinogenesis.