Oncology Commons^™

Tgfβ/Smad3 Regulates Proliferation And Apoptosis Through Irs-1 Inhibition In Colon Cancer Cells., Katie L. Bailey, Ekta Agarwal, Sanjib Chowdhury, Jiangtao Luo, Michael G. Brattain, Jennifer D. Black, J. Wang

Journal Articles: Eppley Institute

In this study, we have uncovered a novel crosstalk between TGFβ and IGF-1R signaling pathways. We show for the first time that expression and activation of IRS-1, an IGF-1R adaptor protein, is decreased by TGFβ/Smad3 signaling. Loss or attenuation of TGFβ activation leads to elevated expression and phosphorylation of IRS-1 in colon cancer cells, resulting in enhanced cell proliferation, decreased apoptosis and increased tumor growth in vitro and in vivo. Downregulation of IRS-1 expression reversed Smad3 knockdown-mediated oncogenic phenotypes, indicating that TGFβ/Smad3 signaling inhibits cell proliferation and increases apoptosis at least partially through the inhibition of IRS-1 expression and activation. …

Intra-Tumoral Heterogeneity In Metastatic Potential And Survival Signaling Between Iso-Clonal Hct116 And Hct116b Human Colon Carcinoma Cell Lines., Sanjib Chowdhury, Melanie Ongchin, Elizabeth Sharratt, Ivan Dominguez, J. Wang, Michael G. Brattain, Ashwani Rajput

Journal Articles: Eppley Institute

BACKGROUND: Colorectal cancer (CRC) metastasis is a leading cause of cancer-related deaths in the United States. The molecular mechanisms underlying this complex, multi-step pathway are yet to be completely elucidated. Recent reports have stressed the importance of intra-tumoral heterogeneity in the development of a metastatic phenotype. The purpose of this study was to characterize the intra-tumoral phenotypic heterogeneity between two iso-clonal human colon cancer sublines HCT116 and HCT116b on their ability to undergo metastatic colonization and survive under growth factor deprivation stress (GFDS).

MATERIALS AND METHODS: HCT116 and HCT116b cells were transfected with green fluorescence protein and subcutaneously injected into …

Tgf-Beta Suppresses Vegfa-Mediated Angiogenesis In Colon Cancer Metastasis., Liying Geng, Anathbandhu Chaudhuri, G. Talmon, James L. Wisecarver, J. Wang

Journal Articles: Eppley Institute

The FET cell line, derived from an early stage colon carcinoma, is non-tumorigenic in athymic nude mice. Engineered FET cells that express TGF-α (FETα) display constitutively active EGFR/ErbB signaling. These cells readily formed xenograft tumors in athymic nude mice. Importantly, FETα cells retained their response to TGF-beta-mediated growth inhibition, and, like the parental FET cells, expression of a dominant negative TGF-beta type II receptor (DNRII) in FETα cells (FETα/DNRII) abrogated responsiveness to TGF-beta-induced growth inhibition and apoptosis under stress conditions in vitro and increased metastatic potential in an orthotopic model in vivo, which indicates metastasis suppressor activity of TGF-beta signaling …

Transforming Growth Factor-Β Suppresses Metastasis In A Subset Of Human Colon Carcinoma Cells., Neka A.K. Simms, Ashwani Rajput, Elizabeth A. Sharratt, Melanie Ongchin, Carol A. Teggart, J. Wang, Michael G. Brattain

Journal Articles: Eppley Institute

BACKGROUND: TGFβ signaling has typically been associated with suppression of tumor initiation while the role it plays in metastasis is generally associated with progression of malignancy. However, we present evidence here for an anti-metastatic role of TGFβ signaling.

METHODS: To test the importance of TGFβ signaling to cell survival and metastasis we compared human colon carcinoma cell lines that are either non-tumorigenic with TGFβ response (FET), or tumorigenic with TGFβ response (FETα) or tumorigenic with abrogated TGFβ response via introduction of dominant negative TGFβRII (FETα/DN) and their ability to metastasize. Metastatic competency was assessed by orthotopic transplantation. Metastatic colony formation …

Colon Carcinoma Cells Harboring Pik3ca Mutations Display Resistance To Growth Factor Deprivation Induced Apoptosis., J. Wang, Karen Kuropatwinski, Jennie Hauser, Michael R. Rossi, Yunfei Zhou, Alexis Conway, Julie L.C. Kan, Neil W. Gibson, James K.V. Willson, John K. Cowell, Michael G. Brattain

Journal Articles: Eppley Institute

PIK3CA, encoding the p110alpha catalytic subunit of phosphatidylinositol 3-kinase (PI3K), is mutated in a variety of human cancers. We screened the colon cancer cell lines previously established in our laboratory for PIK3CA mutations and found that four of them harbored gain of function mutations. We have now compared a panel of mutant and wild-type cell lines for cell proliferation and survival in response to stress. There was little difference in PI3K activity between mutant PIK3CA-bearing cells (mutant cells) and wild-type PIK3CA-bearing cells (wild-type cells) under optimal growth conditions. However, the mutant cells showed constitutive PI3K activity during growth factor deprivation …