TY - JOUR
T1 - Epigenetic changes and alternate promoter usage by human colon cancers for expressing DCLK1-isoforms
T2 - Clinical Implications
AU - Oconnell, Malaney R.
AU - Sarkar, Shubhashish
AU - Luthra, Gurinder K.
AU - Okugawa, Yoshinaga
AU - Toiyama, Yuji
AU - Gajjar, Aakash H.
AU - Qiu, Suimin
AU - Goel, Ajay
AU - Singh, Pomila
N1 - Funding Information:
The authors acknowledge the help from Cheryl Simmons for preparing the manuscript, and thank Drs. Carla Kantara and Iryna Pinchuk for providing CCD841 and CT26 cells, respectively. These cell lines were purchased by the investigators from ATCC within the past two years. Funding: This work was supported by National Institutes of Health (http://www.nih.gov/) grants CA97959 and CA97959S1 to PS and CA72851 and CA181572 to AG. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
PY - 2015/10/8
Y1 - 2015/10/8
N2 - DCLK1 specifically marks colon/pancreatic cancers in mice, and is expressed by human colon adenocarcinomas (hCRCs). Down-regulation of DCLK1 results in loss of cancer-stem-cells (CSCs), and inhibits spheroidal/xenograft growths from hCRC-cells. The 5′-promoter of DCLK1-gene is reportedly hypermethylated in hCRCs, resulting in loss of expression of DCLK1-transcripts, originating from 5′(α)-promoter (termed DCLK1-L, in here). However, in mouse colon-tumors, 5′-promoter of DCLK1-gene remains unchanged, and DCLK1-L, originating from 5′(α)-promoter, is expressed. We hypothesized that elevated levels of DCLK1-protein in hCRC-cells, may be transcribed/translated from an alternate-promoter. Several in silico and molecular biology approaches were used to test our hypothesis. We report for the first time that majority of hCRCs express short-transcripts of DCLK1 (termed DCLK1-S, in here) from an alternate β-promoter in IntronV of the gene, while normal-colons mainly express DCLK1-L from 5′(α)-promoter. We additionally report an important role of β-catenin and TCF4/LEF binding-sites for activating (α)-promoter, while activated NF-Bp65 (bound to NF-B-cis-element), activates (β)-promoter in cancer-cells. DCLK1-S expression was examined in a cohort of 92 CRC patients; high-expressors had significantly worse overall-survival compared to low-expressors. Our novel findingsregarding usage of alternate (β)-promoter by hCRCs, suggests that DCLK1-S may represent an important target for preventing/inhibiting colon-cancers, and for eliminating colon-CSCs.
AB - DCLK1 specifically marks colon/pancreatic cancers in mice, and is expressed by human colon adenocarcinomas (hCRCs). Down-regulation of DCLK1 results in loss of cancer-stem-cells (CSCs), and inhibits spheroidal/xenograft growths from hCRC-cells. The 5′-promoter of DCLK1-gene is reportedly hypermethylated in hCRCs, resulting in loss of expression of DCLK1-transcripts, originating from 5′(α)-promoter (termed DCLK1-L, in here). However, in mouse colon-tumors, 5′-promoter of DCLK1-gene remains unchanged, and DCLK1-L, originating from 5′(α)-promoter, is expressed. We hypothesized that elevated levels of DCLK1-protein in hCRC-cells, may be transcribed/translated from an alternate-promoter. Several in silico and molecular biology approaches were used to test our hypothesis. We report for the first time that majority of hCRCs express short-transcripts of DCLK1 (termed DCLK1-S, in here) from an alternate β-promoter in IntronV of the gene, while normal-colons mainly express DCLK1-L from 5′(α)-promoter. We additionally report an important role of β-catenin and TCF4/LEF binding-sites for activating (α)-promoter, while activated NF-Bp65 (bound to NF-B-cis-element), activates (β)-promoter in cancer-cells. DCLK1-S expression was examined in a cohort of 92 CRC patients; high-expressors had significantly worse overall-survival compared to low-expressors. Our novel findingsregarding usage of alternate (β)-promoter by hCRCs, suggests that DCLK1-S may represent an important target for preventing/inhibiting colon-cancers, and for eliminating colon-CSCs.
UR - http://www.scopus.com/inward/record.url?scp=84944096224&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84944096224&partnerID=8YFLogxK
U2 - 10.1038/srep14983
DO - 10.1038/srep14983
M3 - Article
C2 - 26447334
AN - SCOPUS:84944096224
SN - 2045-2322
VL - 5
JO - Scientific reports
JF - Scientific reports
M1 - 14983
ER -