Abstract LB-214: Identification of patients with adenomas or early- and late-stage colon carcinomas using nanoporous silica chips for protein profiling
Authors: Tasciotti Ennio , Agostini Marco , Bouamrani Ali , Bedin Chiara , Paredes Yadira , Pucciarelli Salvatore , Nitti Donato , Ferrari Mauro 
Published: February 2011

With more than 600,000 deaths worldwide per year, Colorectal cancer (CRC) is the fifth most common form of cancer in the United States and the third leading cause of cancer-related death in the Western world. The survival rate in CRC patients is mainly influenced by the stage of the disease at the moment of diagnosis, with 5-year survival rates dropping from 95% in stage I to &lt;5% in stage IV. It is widely accepted that the large majority of CRCs develop from adenomatous polyps. The so called “poly dwell time“, the average time required for the transformation of adenomatous polyps to localized cancer, is estimated to be about 10 years. These considerations point at the importance of and at the urgent need for new effective tests for the screening and monitoring of CRC onset and development. Unfortunately, the many progresses in the understanding of the malignant transformations and of the patho-genetic pathways leading to CRC onset did not result in the generation of reliable non-invasive tools for the better and earlier detection of CRC in the clinical practice. The Low Molecular Weight (LMW) region of the blood proteome provides an unprecedented opportunity for clinical diagnosis or prognosis, and for monitoring response to therapy. Proteins and peptides are degraded by proteases in the tumor stromal environment and shed into the circulation from leaky vessels. The LMW peptidome presents an attractive opportunity to capture pathological changes occurring in the tumor tissue and microenvironment. Thus far, the successful translation of this technology to routine clinical application has been limited due to: a) the large dynamic range of blood proteins limiting the detection of LMW, low abundance biomarkers; b) the rapid enzymatic alteration of the specimens due to endogenous and exogenous proteases. We developed a high-throughput, cheap, fast and reliable size-exclusion strategy based on nanoporous silica chips (NSC) for the isolation of LMW species from complex biological samples. In the NSC, pore sizes/structure and surface chemistries act as “processors” for the isolation, enrichment and stabilization of LMW species. In this work we demonstrated the identification of several circulating biomarkers able to significantly and specifically discriminate the patients according to the progression of the malignancy. This pilot study was conducted on the plasma obtained from 2 groups of patients. 1- 80 subjects (48 males and 32 females) with a median age of 68 years (range 38-85) presenting an adenocarcinoma (right colon, n=21; left colon, n=42; rectum, n=17) classified following the TNM staging system (stage IV, n=3; stage III, n=37; stage II, n=26 and stage I, n=14). 2- 29 subjects (14 males and 14 females) with median age of 66 years (range 41-80) presenting adenomatous polyps. Blood samples were obtained before any treatment. The Control group comprised 40 clean-colon healthy subjects. Unsupervised clustering showed a discriminative peptide signature that differentiates the adenoma and the carcinoma patients. We further used supervised PCA to identify specific patterns for early and late stages patients developing colorectal cancer. The surgical specimens, assessed in a standardized way, were reviewed by an independent pathologist, who was unaware of the patient's diagnosis and outcome. The histopathology findings were reported following the American Joint Committee on Cancer TNM (2002) as a confirmation of the diagnostic robustness of the NSCs. In conclusion, the analysis of the NSCs generated MALDI-MS plasma protein profiles showed a distinct pattern in late onset CRC patients with respect to early onset, adenomas and healthy subjects. Significant biomarkers for the early detection and for the assessment of cancer staging have been sequenced and identified using MALDI-MS/MS and LC-MS/MS.

We envision that screenings based on the NSC technology may serve as a complement to histopathology, molecular imaging and other state of the art diagnostic techniques. In the future this approach may allow for the molecular stratification of patients, help in the selection of individualized therapeutic combinations that target the entire cancer-specific protein network, in the real-time assessment of therapeutic efficacy and toxicity, and in the rational modulation of therapy based on changes in the cancer protein network associated with prognosis and drug resistance.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-214.