MicroRNAs (miRNAs) are short non-coding RNA molecules playing regulatory roles by repressing translation or cleaving RNA transcripts. Although the number of verified human miRNA is still expanding, only few have been functionally described. However, emerging evidences suggest the potential involvement of altered regulation of miRNA in pathogenesis of cancers and these genes are thought to function as both tumours suppressor and oncogenes.

Background: Methods: Results: Conclusion:

Recent advances in the field of RNA research have provided compelling evidence implicating microRNA (miRNA) and long non-coding RNA molecules in many diverse and substantial biological processes, including transcriptional and post-transcriptional regulation of gene expression, genomic imprinting, and modulation of protein activity. Thus, studies of non-coding RNA (ncRNA) may contribute to the discovery of possible biomarkers in human cancers. Considering that the response to chemotherapy can differ amongst individuals, researchers have begun to isolate and identify the genes responsible. Identification of targets of this ncRNA associated with cancer can suggest that networks of these linked to oncogenes or tumor suppressors play pivotal roles in cancer development. Moreover, these ncRNA are attractive drug targets since they may be differentially expressed in malignant versus normal cells and regulate expression of critical proteins in the cell. This review focuses on ncRNAs that are differently expressed in malignant tissue, and discusses some of challenges derived from their use as potential biomarkers of tumor properties.

AIM: To evaluate the potential association of xeroderma pigmentosum group D (XPD) codon 751 variant with outcome after chemo-radiotherapy in patients with resected gastric cancer. METHODS: We used PCR-RFLP to evaluate the genetic XPD Lys751Gln polymorphisms in 44 patients with stage III (48%) and IV (20%) gastric cancer treated with surgery following radiation therapy plus 5-fluorouracil/leucovorin based chemotherapy. RESULTS: Statistical analysis showed that 75% (12 of 16) of relapse patients showed Lys/Lys genotype more frequently (P = 0.042). The Lys polymorphism was an independent predictor of high-risk relapse-free survival from Cox analysis (HR: 3.07, 95% CI: 1.07-8.78, P = 0.036) and Kaplan-Meir test (P = 0.027, log-rank test). CONCLUSION: XPD Lys751Gln polymorphism may be an important marker in the prediction of clinical outcome to chemo-radiotherapy in resected gastric cancer patients.

We have analyzed several members of drug-metabolizing enzymes (DMEs) and other polymorphisms in genes implicated in tumor aggressivity regarding possible links between specific genetic variability in systemic drug bioavailability and toxicity in breast cancer patients treated with adjuvant anthracycline-based treatment. PCR-RFLP and sequencing analyses technique were used for evaluating fourteen previously identified polymorphisms in 94 patients. GSTP1A > G and MTHFR 1298A > C genotypes remained as significant predictors in a multivariate logistic regression analysis. GSTP1 polymorphism was linked to haematological GIII-IV toxicity (P = 0.044, HR= 6.4, 95% CI = 1.05 to 39. Increased and significant HR was obtained for MTHFR-1298 AC+CC group when non-haematological toxicities GIII-IV toxicities were evaluated (HR = 24; 95% CI = 2.3 to 254), P = 0.008. Our results suggest that GSTP1 and MTHFR genotypes may be consider relevant and independent factors of toxicity in adjuvant anthracycline- based treatment of breast cancer.

Our aim was to evaluate the role of C-69T in GSTA1, Ile105Val in GSTP1, null allele in GSTT1 and GSTM1 in the prediction of toxicity in patients treated with 5-Fu/CPT-11/Lv regimens in metastatic CRC patients. Fifty-one patients with CRC metastatic disease were analysed. All patients had bidimensionally measurable disease according to WHO criteria. The gender distribution was 37 (74%) males and 13 (26%) females; age ranged from 41 to 71 years; performance status was in all patients > or = 80 (Karnofsky index). The analysis of gene polymorphism was performed in lymphocytes by using PCR-RFLP (GSTA1, GSTP1), PCR (GSTT1, GSTM1) and sequencing analysis (UGT1A1 *28). An appreciable significant association was observed between the GSTT1-null and toxicity: 57% developed gastrointestinal toxicity grade III versus 23% of patients with GSTT1-present genotype (p = 0.053). The other polymorphisms analysed did not show any significant relation with toxicity. Our data suggest that GSTT1-null is associated with a greater probability of developing toxicity to 5-Fu/CPT-11/Lv treatments, indicating a potential application of this genetic analysis in predicting adverse effects of this regimen.