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Triple-negative breast cancer (TNBC) is defined by the lack of three receptors (estrogen, progesterone, and HER2 receptors) and accounts for 12-17% of breast cancers. TNBC is an aggressive form of the disease associated with high rates of recurrence and mortality within five years. Inhibitor of Growth 4 (ING4)

Triple-negative breast cancer (TNBC) is defined by the lack of three receptors (estrogen, progesterone, and HER2 receptors) and accounts for 12-17% of breast cancers. TNBC is an aggressive form of the disease associated with high rates of recurrence and mortality within five years. Inhibitor of Growth 4 (ING4) is a gene deleted in 16.5% and downregulated in 34% of breast tumors. The correlation between ING4 deficiencies and advanced tumors and poor patient survival implicates its tumor suppressive function in breast cancer. Low ING4 expression has been correlated with NFκB activation in metastatic breast tumors. Moreover, ING4 has been shown to inhibit NFkB-mediated gene transcription in various cancers, suggesting that ING4 may suppress cancer by inhibiting NFkB activation. However, the contribution of ING4 deficiencies and NFkB activation to aggressive TNBC progression is currently not well understood. We investigated the role of ING4 in the MDAmb231 TNBC cell line by genetically engineering the cells to overexpress or delete ING4. Cell growth and sensitivity to the chemotherapeutic agent doxorubicin were evaluated between the ING4-modified cell lines with or without TNFα to activate NFκB. The results showed that cell growths were comparable between the vector controls and ING4 overexpressing or deleted cell lines. In addition, TNFα treatment did not alter the growths of all cell lines, indicating that ING4 with or without NFkB activation did not play a role in determining the growth rates of TNBC. However, ING4 overexpressing cells were 20-30% more sensitive to 10 μM doxorubicin treatment, whereas ING4-deleted cells were 20-50% more resistant, suggesting that ING4 may determine chemotherapy response in TNBC. These findings suggest that tumors with low levels of ING4 may be more resistant to chemotherapy, thus requiring higher dosage and/or additional chemotherapy in patient treatment. Unexpectedly, TNFα sensitized all cell lines to doxorubicin regardless of ING4 expression levels, suggesting a TNFα function outside of NFκB activation in increasing doxorubicin sensitivity. It implicates that TNFα treatment may increase chemotherapy response in TNBC patients.
ContributorsUngor, Ashley Jordyn (Author) / Capco, David (Thesis director) / Kim, Suwon (Committee member) / Compton, Carolyn (Committee member) / Sanford School of Social and Family Dynamics (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2017-12
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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

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.

ContributorsPedroza, Morgan Arielle (Author) / Kim, Suwon (Thesis director) / Wagner, Carl (Thesis director) / Bussey, Kimberly (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Natural Sciences (Contributor)
Created2021-12
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Inhibitor of growth factor 4 (ING4) is a tumor suppressor of which low expression has been associated with poor patient survival and aggressive tumor progression in breast cancer. ING4 is characterized as a transcription regulator of inflammatory genes. Among the ING4-regulated genes is CXCL10, a chemokine secreted by endothelial cells

Inhibitor of growth factor 4 (ING4) is a tumor suppressor of which low expression has been associated with poor patient survival and aggressive tumor progression in breast cancer. ING4 is characterized as a transcription regulator of inflammatory genes. Among the ING4-regulated genes is CXCL10, a chemokine secreted by endothelial cells during normal inflammation response, which induces chemotactic migration of immune cells to the site. High expression of CXCL10 has been implicated in aggressive breast cancer, but the mechanism is not well understood. A potential signaling molecule downstream of Cxcl10 is Janus Kinase 2 (Jak2), a kinase activated in normal immune response. Deregulation of Jak2 is associated with metastasis, immune evasion, and tumor progression in breast cancer. Thus, we hypothesized that the Ing4/Cxcl10/Jak2 axis plays a key role in breast cancer progression. We first investigated whether Cxcl10 affected breast cancer cell migration. We also investigated whether Cxcl10-mediated migration is dependent on ING4 expression levels. We utilized genetically engineered MDAmb231 breast cancer cells with a CRISPR/Cas9 ING4-knockout construct or a viral ING4 overexpression construct. We performed Western blot analysis to confirm Ing4 expression. Cell migration was assessed using Boyden Chamber assay with or without exogenous Cxcl10 treatment. The results showed that in the presence of Cxcl10, ING4-deficient cells had a two-fold increase in migration as compared to the vector controls, suggesting Ing4 inhibits Cxcl10-induced migration. These findings support our hypothesis that ING4-deficient tumor cells have increased migration when Cxcl10 signaling is present in breast cancer. These results implicate Ing4 is a key regulator of a chemokine-induced tumor migration. Our future plan includes evaluation of Jak2 as an intermediate signaling molecule in Cxcl10/Ing4 pathway. Therapeutic implications of these findings are targeting Cxcl10 and/or Jak2 may be effective in treating ING4-deficient aggressive breast cancer.
ContributorsArnold, Emily (Author) / Kim, Suwon (Thesis director) / Blattman, Joseph (Thesis director) / Mason, Hugh (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05