Garlic has been linked to reduced breast cancer risk in multiple studies, largely due to its organosulfur content. Such compounds have been shown to inhibit DNA synthesis, retard growth, and suppress angiogenesis in triple negative (ER-/PR-/HER2-) and ER+/PR+ cells. Now a new study has reported that diallyl disulfide's influence on the invasiveness of HER2-positive (HER2+) breast cancer cells depends on exposure.
Organosulfur compounds found in garlic include allicin, diallyl sulfide, diallyl disulfide, diallyl trisulfide, diallyltetrasulfide, and dipropyltetrasulfide, among others. Several organosulfur compounds have been shown to inhibit breast cancer cell growth and proliferation by interfering with the cell cycle. Diallyl trisulfide has been shown to suppress breast cancer cell invasion and metastasis, thereby delaying the onset or progression of breast cancer.
Organosulfur compounds are produced upon cutting or chewing garlic. Although some of the anticancer benefits of garlic are retained after cooking or processing it, raw garlic appears to have the most benefits.
Latest research finds variable effects of diallyl disulfide
The study referenced above was designed to investigate how the garlic compound diallyl disulfide can influence the invasiveness of HER2+ breast cancer cells. To conduct the study, the authors assessed the effects of both diallyl disulfide and a garlic extract on two ER-/PR-/HER2+ breast cancer cell lines ( MDA-MB-453 and SKBR3).
After four to 72 hours of administration, cell growth, invasive potential, and Akt-related signaling were assessed. Activation of the Akt gene is frequently observed in human cancer cells. The intracellular localization of β-catenin was also evaluated by the authors. β-catenin is one of the key components of the Wnt signaling pathway. The Wnt signaling pathway sends β-catenin into the cell nucleus to activate the EMT cell transitions that cancer cells undergo in the process of becoming capable of metastasis. Inhibition of β-catenin signaling appears to play a central role in the anticancer activity of certain micronutrients.
The authors report, for the first time, that diallyl disulfide can have a variable effect in HER2+ cells, depending on the duration of treatment. Acute, short-term administration resulted in a significant reduction in invasive potential, whereas prolonged treatment promoted HER2+ cell invasiveness. The latter result was concomitant with observed activation of Akt and nuclear accumulation of β-catenin, both associated with tumor malignancy.
The authors comment that further investigations are needed to establish the exact mechanism of action underlying their results and to assess their reproducibility in animal studies. However, the results highlight the potential for variable responses of complex diseases like cancer to natural compounds.