Chemotherapy and TRAIL-mediated colon cancer cell death: the roles of p53, TRAIL receptors, and c-FLIP.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has recently attracted attention as a potential therapeutic agent in the treatment of cancer. We assessed the roles of p53, TRAIL receptors, and cellular Fas-associated death domain-like interleukin-1beta-converting enzyme inhibitory protein (c-FLIP) in regulating the cytotoxic effects of recombinant TRAIL (rTRAIL) alone and in combination with chemotherapy [5-fluorouracil (5-FU), oxaliplatin, and irinotecan] in a panel of colon cancer cell lines. Using clonogenic survival and flow cytometric analyses, we showed that chemotherapy sensitized p53 wild-type, mutant, and null cell lines to TRAIL-mediated apoptosis. Although chemotherapy treatment did not modulate mRNA or cell surface expression of the TRAIL receptors death receptor 4, death receptor 5, decoy receptor 1, or decoy receptor 2, it was found to down-regulate expression of the caspase-8 inhibitor, c-FLIP. Stable overexpression of the long c-FLIP splice form but not the short form was found to inhibit chemotherapy/rTRAIL-induced apoptosis. Furthermore, siRNA-mediated down-regulation of c-FLIP, particularly the long form, was found to sensitize colon cancer cells to rTRAIL-induced apoptosis. In addition, treatment of a 5-FU-resistant cell line with 5-FU down-regulated c-FLIP expression and sensitized the chemotherapy-resistant cell line to rTRAIL. We conclude that TRAIL-targeted therapies may be used to enhance conventional chemotherapy regimens in colon cancer regardless of tumor p53 status. Furthermore, inhibition of c-FLIP may be a vital accessory strategy for the optimal use of TRAIL-targeted therapies.

Family communication, genetic testing and colonoscopy screening in hereditary non-polyposis colon cancer: a qualitative study

Objective: Genetic testing and colonoscopy is recommended for people with a strong history of colorectal cancer (CRC). However, families must communicate so that all members are aware of the risk. The study aimed to explore the factors influencing family communication about genetic risk and colonoscopy among people with a strong family history of CRC who attended a genetic clinic with a view to having a genetic test for hereditary non-polyposis colon cancer (HNPCC).

Prognostic and Predictive Biomarkers in Resected Colon Cancer: Current Status and Future Perspectives for Integrating Genomics into Biomarker Discovery

The number of agents that are potentially effective in the adjuvant treatment of locally advanced resectable colon cancer is increasing. Consequently, it is important to ascertain which subgroups of patients will benefit from a specific treatment. Despite more than two decades of research into the molecular genetics of colon cancer, there is a lack of prognostic and predictive molecular biomarkers with proven utility in this setting. A secondary objective of the Pan European Trials in Adjuvant Colon Cancer-3 trial, which compared irinotecan in combination with 5-fluorouracil and leucovorin in the postoperative treatment of stage III and stage II colon cancer patients, was to undertake a translational research study to assess a panel of putative prognostic and predictive markers in a large colon cancer patient cohort. The Cancer and Leukemia Group B 89803 trial, in a similar design, also investigated the use of prognostic and predictive biomarkers in this setting. In this article, the authors, who are coinvestigators from these trials and performed similar investigations of biomarker discovery in the adjuvant treatment of colon cancer, review the current status of biomarker research in this field, drawing on their experiences and considering future strategies for biomarker discovery in the postgenomic era. The Oncologist 2010; 15: 390-404

Tissue biomarker development in a multicentre trial context: a feasibility study on the PETACC3 stage II and III colon cancer adjuvant treatment trial.

Purpose: We evaluated the feasibility of biomarker development in the context of multicenter clinical trials.

Experimental Design: Formalin-fixed, paraffin-embedded (FFPE) tissue samples were collected from a prospective adjuvant colon cancer trial (PETACC3). DNA was isolated from tumor as well as normal tissue and used for analysis of microsatellite instability, KRAS and BRAF genotyping, UGT1A1 genotyping, and loss of heterozygosity of 18 q loci. Immunohistochemistry was used to test expression of TERT, SMAD4, p53, and TYMS. Messenger RNA was retrieved and tested for use in expression profiling experiments.

Results: Of the 3,278 patients entered in the study, FFPE blocks were obtained from 1,564 patients coming from 368 different centers in 31 countries. In over 95% of the samples, genomic DNA tests yielded a reliable result. Of the immmunohistochemical tests, p53 and SMAD4 staining did best with reliable results in over 85% of the cases. TERT was the most problematic test with 46% of failures, mostly due to insufficient tissue processing quality. Good quality mRNA was obtained, usable in expression profiling experiments.

Conclusions: Prospective clinical trials can be used as framework for biomarker development using routinely processed FFPE tissues. Our results support the notion that as a rule, translational studies based on FFPE should be included in prospective clinical trials.

Development and independent validation of a prognostic assay for stage ii colon cancer using formalin-fixed paraffin-embedded tissue

Purpose: Current prognostic factors are poor at identifying patients at risk of disease recurrence after surgery for stage II colon cancer. Here we describe a DNA microarray-based prognostic assay using clinically relevant formalin-fixed paraffin-embedded (FFPE) samples. Patients and Methods: A gene signature was developed from a balanced set of 73 patients with recurrent disease (high risk) and 142 patients with no recurrence (low risk) within 5 years of surgery. Results: The 634-probe set signature identified high-risk patients with a hazard ratio (HR) of 2.62 (P <.001) during cross validation of the training set. In an independent validation set of 144 samples, the signature identified high-risk patients with an HR of 2.53 (P <.001) for recurrence and an HR of 2.21 (P = .0084) for cancer-related death. Additionally, the signature was shown to perform independently from known prognostic factors (P <.001). Conclusion: This gene signature represents a novel prognostic biomarker for patients with stage II colon cancer that can be applied to FFPE tumor samples. © 2011 by American Society of Clinical Oncology.