Differential expression of colon cancer associated transcript1 (CCAT1) along the colonic adenoma-carcinoma sequence.

BACKGROUND: The transition from normal epithelium to adenoma and, to invasive carcinoma in the human colon is associated with acquired molecular events taking 5-10 years for malignant transformation. We discovered CCAT1, a non-coding RNA over-expressed in colon cancer (CC), but not in normal tissues, thereby making it a potential disease-specific biomarker. We aimed to define and validate CCAT1 as a CC-specific biomarker, and to study CCAT1 expression across the adenoma-carcinoma sequence of CC tumorigenesis. METHODS: Tissue samples were obtained from patients undergoing resection for colonic adenoma(s) or carcinoma. Normal colonic tissue (n = 10), adenomatous polyps (n = 18), primary tumor tissue (n = 22), normal mucosa adjacent to primary tumor (n = 16), and lymph node(s) (n = 20), liver (n = 8), and peritoneal metastases (n = 19) were studied. RNA was extracted from all tissue samples, and CCAT1 expression was analyzed using quantitative real time-PCR (qRT-PCR) with confirmatory in-situ hybridization (ISH). RESULTS: Borderline expression of CCAT1 was identified in normal tissue obtained from patients with benign conditions [mean Relative Quantity (RQ) = 5.9]. Significant relative CCAT1 up-regulation was observed in adenomatous polyps (RQ = 178.6 ± 157.0; p = 0.0012); primary tumor tissue (RQ = 64.9 ± 56.9; p = 0.0048); normal mucosa adjacent to primary tumor (RQ = 17.7 ± 21.5; p = 0.09); lymph node, liver and peritoneal metastases (RQ = 11,414.5 ± 12,672.9; 119.2 ± 138.9; 816.3 ± 2,736.1; p = 0.0001, respectively). qRT-PCR results were confirmed by ISH, demonstrating significant correlation between CCAT1 up-regulation measured using these two methods. CONCLUSION: CCAT1 is up-regulated across the colon adenoma-carcinoma sequence. This up-regulation is evident in pre-malignant conditions and through all disease stages, including advanced metastatic disease suggesting a role in both tumorigenesis and the metastatic process.

Colon cancer associated transcript-1: a novel RNA expressed in malignant and pre-malignant human tissues.

Early detection of colorectal cancer (CRC) is currently based on fecal occult blood testing (FOBT) and colonoscopy, both which can significantly reduce CRC-related mortality. However, FOBT has low-sensitivity and specificity, whereas colonoscopy is labor- and cost-intensive. Therefore, the discovery of novel biomarkers that can be used for improved CRC screening, diagnosis, staging and as targets for novel therapies is of utmost importance. To identify novel CRC biomarkers we utilized representational difference analysis (RDA) and characterized a colon cancer associated transcript (CCAT1), demonstrating consistently strong expression in adenocarcinoma of the colon, while being largely undetectable in normal human tissues (p < 000.1). CCAT1 levels in CRC are on average 235-fold higher than those found in normal mucosa. Importantly, CCAT1 is strongly expressed in tissues representing the early phase of tumorigenesis: in adenomatous polyps and in tumor-proximal colonic epithelium, as well as in later stages of the disease (liver metastasis, for example). In CRC-associated lymph nodes, CCAT1 overexpression is detectable in all H&E positive, and 40.0% of H&E and immunohistochemistry negative lymph nodes, suggesting very high sensitivity. CCAT1 is also overexpressed in 40.0% of peripheral blood samples of patients with CRC but not in healthy controls. CCAT1 is therefore a highly specific and readily detectable marker for CRC and tumor-associated tissues.

Development of a microRNA-based molecular assay for the detection of papillary thyroid carcinoma in aspiration biopsy samples.

BACKGROUND: Although thyroid nodules are common and diagnosed in over 5% of the adult population, only 5% harbor malignancy. Patients with clinically suspicious thyroid nodules need to undergo fine-needle aspiration biopsy (FNAB). The main limitation of FNAB remains indeterminate cytopathology. Only 20%-30% of the indeterminate nodules harbor malignancy, and therefore up to 80% of patients undergo unnecessary thyroidectomy. The aim of this study was to identify and validate a panel of microRNAs (miRNAs) that could serve as a platform for an FNAB-based diagnostic for thyroid neoplasms. METHODS: The study population included 27 consecutive patients undergoing total thyroidectomy for FNAB-based papillary thyroid cancer (n = 20) and benign disorders (n = 7). Aspiration biopsy was performed from the index lesion and from the opposite lobe normal tissue in all study patients at the time of operation. RNA was extracted from all aspiration biopsy samples. Quantitative polymerase chain reaction on a panel of previously selected miRNAs was performed. Polymerase chain reaction results were compared with final histopathology. miRNA from tumor tissues was amplified using the highest value of each miRNA expression in normal tissue as a threshold for malignancy detection. RESULTS: Diagnostic characteristics were most favorable for mir-221 in differentiating benign from malignant thyroid pathology. mir-221 was overexpressed in 19 patients (p < 0.0001) with a sensitive yield of 95%. Specificity, negative and positive predictive value, and accuracy of the miRNA panel were 100%, 96%, 100%, and 98%, respectively. CONCLUSIONS: miRNA quantification for differential diagnosis of thyroid neoplasms within aspiration biopsy samples is feasible and may improve the accuracy of FNAB cytology.