Analysis of Specific Transcriptional Regulators as Early Predictors of Independent Prognostic Relevance in Resected Colorectal Cancer

Abstract

Purpose: Prognostic studies on transcription factors acting at specific promoter elements have never been done so far. However, in tumors with long necessary follow-up, such as colorectal cancer, early-risk predictors would be needed. The invasion-related gene u-PAR is regulated via an activator protein 2 (AP-2)/Sp1 (À152/À135) and an AP-1binding promoter motif (À190/ À171), mediating u-PAR induction by K-Ras and Src. The present study was done to give first evidence for early prognostic relevance of transcription factors differentially bound to the u-PAR promoter, and their molecular inducers, in colorectal cancer. Experimental Design: Tumor/normal tissues of 92 prospectively followed (median = 26.3 months) patients were analyzed for Src activity/protein, K-ras mutations, and transcription factor binding to both u-PAR promoter motifs (in vivo gel shift, kinase assay, and PCR). Results: Kaplan-Meier/Mantel-Cox analysis showed a significant correlation among elevated Sp1/Sp3 binding to region À152/À135 (P = 0.002 and P = 0.006), the combinations of Sp1/ AP-2 and Sp1/AP-1binding to both motifs (P = 0.010 and P = 0.005), and Sp1binding/high Src protein in tumors (P < 0.001), with poor survival. Survival decreased with the number of bound transcription factors to both motifs, with binding of three factors defining a high-risk group (P = 0.021). In multivariate analysis, elevated Sp1 binding, combinations of Sp1/AP-2 binding and Sp1/AP-1 binding, or Sp1 binding/high Src were independent prognostic variables; u-PAR expression itself being not yet prognostic. A first molecular staging model (CART) was defined, providing novel early high-risk groups (mean survival time as low as for non-curatively resected patients) from these variables. Conclusions: This study defines transcription factors acting at specific promoter elements of an invasion-related gene, mediating specific signaling, as novel, independent, early predictors of prognosis in colorectal cancer.

Src Induces Urokinase Receptor Gene Expression and Invasion/Intravasation via Activator Protein-1/p-c-Jun in Colorectal Cancer

“…Together with our previously published report that Src activity and also cooperation of transcription factors and Src regulating u-PAR are indicators of poor prognosis in colorectal cancer patients (15,31), these results corroborate the notion that Src inhibition and, specifically, an inhibition of Srcinduced u-PAR gene expression mediated by phospho -c-Jun bound to AP-1 motif À190/À171 might be promising strategies to prevent tumor progression and metastasis in colorectal cancer, specifically by inhibiting the decisive initial metastatic steps of invasion and intravasation into the systemic circulation.…”

“…However, because in another recent publication we see a significant correlation of Src activity, AP-1 binding, and u-PAR protein in a larger patient series (n = 92; ref. 31), the most likely explanation for the lack of significance in the present paper is the small case number. Still, the significant correlation between Src and AP-1 and between u-PAR, Src, AP-1 and pN stage supports the in vivo relevance of our present work for colorectal cancer patients.…”

Increased Expression of Colonic Wnt9A through Sp1-mediated Transcriptional Effects involving Arylsulfatase B, Chondroitin 4-Sulfate, and Galectin-3

“…Sp1 was present in 74.8% of colon cancer tissues examined in one series, compared with presence in 42.2% of the normal colonic mucosa examined, and was overexpressed in colonic cancer stem cells (16). Sp1 has also been identified as a prognostic indicator in colorectal cancers (17,18). Many established interactions of Sp1 with other proteins and enzymes involve post-translational modifications and include interactions with histone deacetylases (19).…”

Inhibition of STAT5 induces G1 cell cycle arrest and reduces tumor cell invasion in human colorectal cancer cells

“…In general, the molecular mechanisms that control CRC progression are related to the altered expression of different proto-oncogenes, tumor suppressor genes, cytokines and their receptors, including Ras, Src, p27 kip1 , p16 ink4a , interleukin (IL) and the epidermal growth factor receptor (EGFR). [1][2][3][4][5][6][7] Notably, these abnormalities involve the signal transducers and activators of transcription (STAT) signaling pathway, specifically STAT3 and STAT5 signaling, although very few studies have reported the abnormal expression or activation of STAT proteins in colorectal cancer. 8 Understanding the molecular mechanisms of STATs may further the development of novel therapies targeted in CRC treatment.…”