A new study recently presented at the annual American Association for Cancer Research (AACR) Meeting in Washington, D.C. has reported a mechanism by which the garlic compound diallyl trisulfide can suppress breast cancer cell invasion and metastasis. Poor prognosis of breast cancer is associated with cancer cell invasion and metastasis. Epithelial-mesenchymal transition is a crucial event in the tumor invasion process. The authors recently demonstrated that signal transducers and activators of transcription 5a (Stat5a) and its Janus tyrosine kinase, (Jak2), suppress invasion and promote human breast cancer cell differentiation by means of inhibition of epithelial-to-mesenchymal differentiation.

In the present study, the authors used a combination of Jak2/Stat5a overexpression and histone deacetylase (HDAC) inhibitors (which inhibit proliferation and induce differentiation ), Mistletoe plant extract, and/or diallyl trisulfide (a component of garlic) as a way to inhibit breast cancer invasion and restore differentiation in breast cancer cell cultures and in tumors implanted in mice. The investigation included a variety of human breast cancer cell lines that display different hormone receptor and differentiation patterns (ranging from poor to high differentiation). The cells were pretreated with or without HDAC inhibitors, as well as with mistletoe plant extract and/or diallyl trisulfide, and then either mock infected or actually infected with adenovirus carrying Wild type (Wt-Jak2), Wt-Stat5a, Dominant negative (Dn-Stat5), or a combination of Wt-Jak2 and Wt-Stat5a. Pretreatment with HDAC inhibitors, mistletoe plant extract, and /or diallyl trisulfide was found to act synergistically with co-expression of Wt-Jak2/Stat5a to promote differentiation. The combination induced reduced cell motility and invasiveness.

In further experimentation, human breast cancer tumors were implanted in nude mice. After four weeks, the growth of both estrogen receptor positive (ER+) and estrogen receptor negative (ER-) tumors that co-expressed Wt-Jak2/Stat5a were found to be inhibited by 45.4% and 51.12%, respectively, compared to the untreated control group and by 48.3% and 54.33%, respectively, compared to the group with tumors expressing Dn-Stat5. The authors comment that the findings suggest that a combination of Jak2/Stat5a overexpression and nontoxic agents derived from garlic or mistletoe can delay the onset or progression of breast cancer by restoring lost differentiation of breast cancer through epithelial-mesenchymal transition inhibition. This offers a potential new therapeutic strategy to inhibit human breast cancer progression.

Please see our article on how to optimize your breast cancer diet for information on what to eat during all stages of treatment and recovery.