Synthesis and Characterization of Specific Reverse Transcriptase Inhibitors for Mammalian LINE-1 Retrotransposons.

Retrotransposons are a type of transposable element (TE) that have amplified to astonishing numbers in mammalian genomes, comprising more than a third of the human and mouse genomes. Long interspersed element class 1 (LINE-1 or L1) retrotransposons are abundant and currently active retroelements in the human and mouse genomes. Similarly, long terminal repeat (LTR)-containing retrotransposons are abundant in both genomes, although only active in mice. LTR- and LINE-1-retroelements use different mechanisms for retrotransposition, although both involve the reverse transcription of an intermediate retroelement-derived RNA. Retrotransposon activity continues to effect the germline and somatic genomes, generating interindividual variability over evolution and potentially influencing cancer and brain physiology, respectively. However, relatively little is known about the functional consequences of retrotransposition. In this study, we have synthesized and characterized reverse transcriptase inhibitors specific for mammalian LINE-1 retrotransposons, which might help deciphering the functional impact of retrotransposition in vivo.

Circulating tumor cells criteria (CyCAR) versus standard RECIST criteria for treatment response assessment in metastatic colorectal cancer patients.

BACKGROUND: The use of circulating tumor cells (CTCs) as indicators of treatment response in metastatic colorectal cancer (mCRC) needs to be clarified. The objective of this study is to compare the Response Evaluation Criteria in Solid Tumors (RECIST) with the Cytologic Criteria Assessing Response (CyCAR), based on the presence and phenotypic characterization of CTCs, as indicators of FOLFOX-bevacizumab treatment response. METHODS: 77 mCRC blood samples from FOLFOX-bevacizumab treated patients were analyzed to isolate CTCs before and after (12 and 24 weeks) treatment, using an immunomagnetic separation method. VEGFR expression was identified by double immunostaining. RESULTS: We observed a decrease of CTCs (42.8 vs. 18.2%) and VEGFR positivity (69.7% vs. 41.7%) after treatment. According to RECIST, 6.45% of the patients did not show any clinical benefit, whereas 93.55% patients showed a favorable response at 12 weeks. According to CyCAR, 29% had a non-favorable response and 71% patients did not. No significant differences were found between the response assessment by RECIST and CyCAR at 12 or 24 weeks. However, in the multivariate analysis, RECIST at 12 weeks and CyCAR at 24 weeks were independent prognostic factors for OS (HR: 0.1, 95% CI 0.02-0.58 and HR: 0.35, 95% CI 0.12-0.99 respectively). CONCLUSIONS: CyCAR results were comparable to RECIST in evaluating the response in mCRC and can be used as an alternative when the limitation of RECIST requires additional response analysis techniques.

A comprehensive study of circulating tumour cells at the moment of prostate cancer diagnosis: biological and clinical implications of EGFR, AR and SNPs.

Circulating tumor cells (CTCs) have been recently accepted as prognostic markers in metastatic prostate cancer (PCa). However, very few studies have analyzed their role in early-stage PCa. The aim of this research is to study the value of CTCs at the moment of PCa diagnosis and to identify different subpopulations of CTCs. Patients with PSA value > 4 ng/ml and clinical suspicion of PCa were included. Samples were collected immediately before prostatic biopsy. CTCs were isolated by immunomagnetic technique using a multi-CK specific antibody. Molecular expression of EGFR and AR in the tissue was analysed by real-time PCR. Up to eight different SNPs in patients' blood DNA were studied. In a total of 86 patients, the CTC detection rate was 18.6%. The sensitivity, specificity, positive and negative predictive values of CTCs to detect PCa was 14.2%, 78.4%, 31.2% and 57.4%, respectively. Up to 75% of CTC-positive patients were AR-negative. A direct association was found between the expression of AR in the prostatic tissue and the presence of CTCs in blood (p<0.05). We observed an inverse relation between the expression of EGFR in the tissue and the expression of AR in the CTCs. No significant association between SNPs and CTCs was found. The low detection rate of CTCs in early-stage PCa limits their role as a diagnostic marker. Nevertheless, we show that they may hide important prognostic information. Overexpression of AR in the prostate may facilitate cell dissemination.

Prognostic factor analysis of circulating tumor cells in peripheral blood of patients with peritoneal carcinomatosis of colon cancer origin treated with cytoreductive surgery plus an intraoperative hyperthermic intraperitoneal chemotherapy procedure (CRS + HIPEC).

PURPOSE: Complete cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) has changed the therapeutic landscape, improving overall survival in patients with peritoneal carcinomatosis with a colonic origin. The main limitation of this aggressive locoregional procedure, however, is extra-abdominal or distant spread. The objective of this study was to identify the prognostic value of circulating tumor cells (CTCs) in patients with peritoneal carcinomatosis of colonic origin undergoing CRS + HIPEC. PATIENTS AND METHODS: Fourteen patients diagnosed with peritoneal carcinomatosis from colon cancer and suitable for potentially curative treatment with CRS + HIPEC were included in this study. CTCs were isolated from the peripheral blood by immunomagnetic techniques by the use of a multi-cytokeratin-specific antibody and detected via immunocytochemical methods. The phenotypic characterization of EGFR on CTCs was analyzed by immunofluorescence. RESULTS: At baseline, 50% of the patients were positive for CTCs, with a mean value of 5.5 CTCs per 10 mL of peripheral blood. After surgery, 28.57% of the patients presented CTCs, with a mean value of 6.75 CTCs per 10 mL. A positive correlation was found between the presence of CTC-negative, epidermal growth factor receptor-positive at baseline and the patients who had symptoms of intestinal obstruction (21.4%). In addition, the presence of CTCs identified patients with distant dissemination and was also significantly correlated with progression-free survival (P = .0024). CONCLUSION: The detection and characterization of CTCs are good prognostic and predictive markers in patients with peritoneal carcinomatosis resulting from colon cancer. These analyses could be used as a new tool to identify subpopulations of patients who could benefit from CRS + HIPEC treatment.

Dormant Circulating Tumor Cells in Prostate Cancer: Therapeutic, Clinical and Biological Implications.

Circulating Tumor Cells (CTCs) are a valuable prognostic factor in several solid tumors. By understanding the biological characteristics of CTCs we could better understand the biology of metastasis. CTCs usually adopt a dormant state that is believed to be a strategy to survive in extreme conditions. To enter a dormant state, CTCs undergo numerous phenotypic, genetic and functional mutations that significantly affect the efficacy of the therapies used to kill dormant CTCs. Hence, understanding the biological events involved in the dormancy process of CTCs would allow the identification of new therapeutic targets. Some experimental studies or preclinical models have explored these biological events, as well as the molecular factors that contribute to the maintenance of and release from dormancy. However, few studies have assessed the effects of anticancer therapies on dormant cells. This study reviews current the data currently available on cell dormancy mechanisms in prostate cancer, with a special focus on the functional, genetic and phenotypic plasticity of CTCs and their potential implications in the clinical and therapeutic management of prostate cancer.

miRNA in situ hybridization in circulating tumor cells--MishCTC.

Circulating tumor cells (CTCs) must be phenotypically and genetically characterized before they can be utilized in clinical applications. Here, we present the first protocol for the detection of miRNAs in CTCs using in situ hybridization (ISH) combined with immunomagnetic selection based on cytokeratin (CK) expression and immunocytochemistry. Locked-Nucleic Acid (LNA) probes associated with an enzyme-labeled fluorescence (ELF) signal amplification approach were used to detect miRNA-21 in CTCs. This protocol was optimized using both epithelial tumor (MDA-MB468) and epithelial non-tumor (MCF-10A) cell lines, and miRNA-21 was selected as the target miRNA because of its known role as an onco-miRNA. Hematopoietic cells do not express miRNA-21; thus, miRNA-21 is an ideal marker for detecting CTCs. Peripheral blood samples were taken from 25 cancer patients and these samples were analyzed using our developed protocol. Of the 25 samples, 11 contained CTCs. For all 11 CTC-positive samples, the isolated CTCs expressed both CK and miRNA-21. Finally, the protocol was applied to monitor miRNA-21 expression in epithelial to mesenchymal transition (EMT)-induced MCF-7 cells, an epithelial tumor cell line. CK expression was lost in these cells, whereas miRNA-21 was still expressed, suggesting that miRNA-21 might be a good marker for detecting CTCs with an EMT phenotype.

EMT and EGFR in CTCs cytokeratin negative non-metastatic breast cancer.

Circulating tumor cells (CTCs) are frequently associated with epithelial-mesenchymal transition (EMT).The objective of this study was to detect EMT phenotype through Vimentin (VIM) and Slug expression in cytokeratin (CK)-negative CTCs in non-metastatic breast cancer patients and to determine the importance of EGFR in the EMT phenomenon. In CK-negative CTCs samples, both VIM and Slug markers were co-expressed in the most of patients. Among patients EGFR+, half of them were positive for these EMT markers. Furthermore, after a systemic treatment 68% of patients switched from CK- to CK+ CTCs. In our experimental model we found that activation of EGFR signaling by its ligand on MCF-7 cells is sufficient to increase EMT phenotypes, to inhibit apoptotic events and to induce the loss of CK expression. The simultaneous detection of both EGFR and EMT markers in CTCs may improve prognostic or predictive information in patients with operable breast cancer.