Piperine, which gives black pepper (Piper nigrum) its spiciness, has been shown to reduce the growth of various types of breast cancer cells without harming normal breast cells. Piperine has also been shown to enhance breast cancer stem cell sensitivity to curcumin, a component of the spice turmeric.
Piperine may enhance the effectiveness of chemotherapy—in fact, piperine appears capable of reversing multidrug resistance. Piperine has also been shown to inhibit mammary tumor growth and metastasis in a mouse model of breast cancer.
Now a new study has reported that piperine reduces triple negative (ER-/PR-/HER2-) breast cancer growth and motility (the ability to move, which is required for metastasis).

Black pepper potentiates some chemotherapy drugs

Piperine has been shown to increase the effectiveness of chemotherapy drugs in cancer cells with multidrug resistance (which reduces the effectiveness of chemotherapy immediately in a few patients or over time in most others). For example, piperine has been found to potentiate the cytotoxicity of Adriamycin in drug resistant hormone receptor positive (ER+/PR+) breast cancer cells.
Piperine has also been shown to increase the therapeutic efficacy of Taxotere (docetaxel). Another black pepper compound, piplartine, led to a higher tumor growth inhibition in combination with 5-fluorouracil (5-FU) in one study.

Latest research finds piperine inhibits triple negative cell growth

The study referenced at the beginning of this news story was designed to investigate the effect of piperine on the growth and motility of triple negative breast cancer cells. Cancer cell motility refers to the ability of tumor cells to move actively, a first step in cell migration, which potentially leads to metastasis. The authors first demonstrated that piperine inhibited the growth of triple negative breast cancer cells, as well as hormone receptor positive breast cancer cells, without affecting normal mammary cell growth.
The authors then determined that exposure of triple negative cells to piperine interfered with progression of the cell cycle, as well as reducing cell survival and promoting apoptosis (programmed cell death). Furthermore, combined treatment with piperine and radiation was found to be more deadly for triple negative breast cancer cells than radiation alone.
Treatment of triple negative cells with piperine reduced migration and lowered expression of matrix metalloproteinase-2 and -9 mRNA (which is associated with tumor progression), suggesting that piperine might inhibit metastasis. Finally, the authors demonstrated piperine inhibited the growth of tumors in mice bearing triple negative tumor grafts. The authors conclude that piperine may be useful in the treatment of triple negative breast cancer.
Please see our articles on black pepper and what triple negative patients and survivors should eat for more information.