Colorectal cancer (CRC) is the third leading cause of cancer related deaths in the
United States. The nuclear factor κB (NF-κB) is an important family of
transcription factors whose aberrant activation has been found in many types of
cancer, including CRC. Therefore, understanding the regulation of NF-κB is of
ultimate importance for cancer therapy. Using a novel validation-based
insertional mutagenesis (VBIM) strategy, our lab has identified the novel
adenomatous polyposis coli (APC) like protein (ALP) gene as a negative
regulator of NF-κB. Preliminary studies from our lab demonstrated that
overexpression of ALP led to decreased NF-κB activity by κB reporter assay and
electrophoresis mobility gel shift assay (EMSA). The current project aims to
further evaluate the role of ALP in the regulation of NF-κB signaling in CRC cells.
We found that overexpression of ALP in human CRC HT29 cells greatly reduced
both the number and the size of colonies that were formed in a soft agar assay.
ALP overexpression also decreased the cell growth rate and cell migration ability,
while shRNA mediated knockdown of ALP showed opposite effects, confirming
that ALP is a tumor suppressor in CRC HT29 cells. Overexpression of ALP led to
decreased NF-κB activity by κB reporter assay and condition media assay in
CRC HT29 cells. Furthermore, immunohistochemical analysis with human colon vii
tissues revealed that there is a gradual loss of ALP protein with tumor
progression. We also found that ALP predominantly localizes in the cytoplasm,
and binds to the p65 subunit of NF-κB, and might be functioning downstream of
IκB kinase (IKK). In summary, in this study, we provide evidence regarding the
tumor suppressor role of ALP in CRC by functioning as novel negative regulator
of NF-κB. This discovery could lead to the establishment of ALP as a potential
biomarker and therapeutic target in CRC.
| Identifer | oai:union.ndltd.org:IUPUI/oai:scholarworks.iupui.edu:1805/6591 |
| Date | 01 1900 |
| Creators | Mundade, Rasika S. |
| Contributors | Lu, Tao, Sullivan Jr., William J., Safa, Ahmad R. |
| Source Sets | Indiana University-Purdue University Indianapolis |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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