Inhibition of NF-kB mediated inflammatory response by parthenolide in breast cancer cells

Triple Negative Breast Cancer (TNBC), indicated by the absence of estrogen, progesterone and human epidermal growth factor receptor 2 (HER2), is the most aggressive form of breast cancer characterized by high rates of metastasis and low survival. Among those diagnosed with TNBC, 34% contain Inhibitor of Growth 4 (ING4) deletion that is associated with poor patient outcomes. We previously showed that ING4 negatively regulates NF-B in breast cancer. Previous studies show parthenolide, a compound found in feverfew (Tanacetum parthenium) to inhibit NF-B in cervical and gastric cancer. We hypothesized that parthenolide inhibits cytokine-induced activation of NF-B in ING4 deficient TNBC cells. To test the hypothesis, previously established vectors, v2, ING4 wildtype and v2h1, ING4-deleted were synthesized in MDA-MB 231, a TNBC cell line, using a CRISPR/Cas9 system. Inflammatory cytokines, IL-1 and TNF, were tested in ING4 wildtype or ING4 deleted cells for elicited phosphorylation of NF-B, proliferation, and migration in the presence or absence of parthenolide. The results showed that TNF or IL-1 induced translocation phosphorylation of NF-B regardless of ING4 deletion. ING4 inhibited proinflammatory cytokine induced pp65, consistent with previous studies demonstrating the negative regulation of NF-B in ING4-sufficent cell lines. We found the optimal working dose of parthenolide, 100nM, had no effect on cell proliferation in the presence or absence of IL-1. Parthenolide inhibited IL-1induced phosphorylation of NF-B regardless of ING4 deletion. Parthenolide inhibited TNF-induced phosphorylation of NF-B in ING4-deleted cell lines. Moreover, parthenolide induced migration of TNBC cells regardless of ING4 presence of absence. TNF and parthenolide treated samples in ING4-deleted cell lines were found to inhibit cell migration to basal level. These results demonstrate the difference in inhibitory mechanism of parthenolide in induced phosphorylation of NF-B through proinflammatory cytokines TNF or IL-1This is demonstrated by the exclusivity of parthenolide inhibition of TNF induced phosphorylation of NF-B in ING4-deleted TNBC cell line. In contrast, parthenolide inhibition of IL-1 induced phosphorylation of NF-B occurred regardless of ING4 deletion. These results may inhibit parthenolide as an alternative to those with ING4-deleted TNBC due to its role in inducing cancer phenotype cell migration.