Antitumorigenic Effect of Tramadol and Synergistic Effect With Doxorubicin in Human Breast Cancer Cells

BACKGROUND: Breast cancer in women is one of the leading causes of cancer mortality worldwide, and curative therapy is the main focus of clinical treatment. Anesthetic-analgesic techniques might alter stress responses and immunity and thereby influence outcomes in cancer patients. This study investigated the effect of tramadol on breast cancer progression and metastasis. METHODS: The effects of tramadol on two different subtypes of human breast adenocarcinoma cell lines, MDA-MB-231 and MCF-7, were studied with regard to cell growth, migration, colony formation and invasion and normoxic or hypoxic microenvironment for the expression of hypoxia-inducible factor-1α, reactive oxygen species, epithelial-mesenchymal transition related and cyclin-related proteins. The co-administration of tramadol and doxorubicin was studied to determine whether the effective doxorubicin dose might be reduced in combination with tramadol. RESULTS: The results showed that tramadol inhibited cell growth at concentrations more than 0.5 and more than 1.0 mg/mL in MDA-MB-231 and MCF-7 cells, respectively. Additionally, cell migration, colony formation and invasion were inhibited in a dose-dependent manner by tramadol in both cell lines. The combination of tramadol and doxorubicin induced synergistic effects in MDA-MD-231 cells and, with specific dosage combinations in MCF-7 cells. CONCLUSIONS: Tramadol may regulate epithelial-mesenchymal transition and possess cytotoxic effects in breast cancer cells. Tramadol inhibits the progression of breast cancer cells and might be a candidate for combination therapy, especially for triple-negative breast cancer, and is a promising treatment strategy for breast cancer.