MicroRNAs are aberrantly expressed and correlate with tumourigenesis and the progression of solid tumours. The miR-200 family determines the epithelial phenotype of cancer cells and regulates invasiveness and migration. Thus, we hypothesised that the quantitative detection of the miR-200 family as epithelial-specific microRNAs in the blood could be a useful clinical biomarker for gastric cancer (GC).

The deregulation of microRNAs in both tumours and blood has led to the search for microRNAs to indicate the presence of cancer and predict prognosis. We hypothesize the deregulation of miR-200c/miR-141 in the whole blood can identify breast cancer (BC), and could be developed into a prognostic signature. The expression of miR-200c and miR-141 were examined in bloods (57 stage I-IV BC patients and 20 age-matched controls) by quantitative reverse-transcription PCR. The associations of circulating microRNAs with clinic and pathological characteristics were analysed. Their effects on survival were analysed by the Kaplan-Meier method and Cox regressions. MiR-200c was down regulated (P < 0.0001) in the blood of BC patients, yielded an area under the ROC curve of 0.79 (90% sensitivity, 70.2% specificity) in discriminating BC from controls. Circulating miR-141 was not discriminating. MiR-200c and miR-141 in the blood of BC patients were inversely correlated (P = 0.019). The miR-200c levels were numerically higher in stage IV and tumours with lower MIB-1. MiR-141 was significantly higher in the blood of patients with stage I-III, lymph node metastasis, and HER2 negative tumours. High blood expression of miR-200c and/or low expression of miR-141 was associated with unfavourable overall survival (hazard ratio, 3.89; [95% CI: 1.28-11.85]) and progression-free survival (3.79 [1.41–10.16]) independent of age, stage and hormonal receptors. Circulating miR-200c and miR-141 were deregulated in BC comparing with controls. Furthermore, miR-200c and miR-141 were independent prognostic factors and associated with distinct outcomes of BC patients.

Colorectal cancer is a heterogeneous disease that manifests through diverse clinical scenarios. During many years, our knowledge about the variability of colorectal tumors was limited to the histopathological analysis from which generic classifications associated with different clinical expectations are derived. However, currently we are beginning to understand that under the intense pathological and clinical variability of these tumors there underlies strong genetic and biological heterogeneity. Thus, with the increasing available information of inter-tumor and intra-tumor heterogeneity, the classical pathological approach is being displaced in favor of novel molecular classifications. In the present article, we summarize the most relevant proposals of molecular classifications obtained from the analysis of colorectal tumors using powerful high throughput techniques and devices. We also discuss the role that cancer systems biology may play in the integration and interpretation of the high amount of data generated and the challenges to be addressed in the future development of precision oncology. In addition, we review the current state of implementation of these novel tools in the pathological laboratory and in clinical practice.

We aim to estimate the diagnostic performances of anterior gradient homolog-2 (AGR2) and Leucine-rich repeat-containing-G-protein-coupled receptor 5 (LGR5) in peripheral blood (PB) as mRNA biomarkers in colorectal cancer (CRC) and to explore their prognostic significance. Real-time PCR was used to analyze AGR2 and LGR5 in 54 stages I-IV CRC patients and 19 controls. Both mRNAs were significantly increased in PB from CRC patients compared to controls. The area under the receiver-operating characteristic curves were 0.722 (p = 0.006), 0.376 (p = 0.123) and 0.767 (p = 0.001) for AGR2, LGR5 and combined AGR2/LGR5, respectively. The AGR2/LGR5 assay resulted in 67.4% sensitivity and 94.7% specificity. AGR2 correlated with pT3–pT4 and high-grade tumors. LGR5 correlated with metastasis, R2 resections and high-grade. The progression-free survival (PFS) of patients with high AGR2 was reduced (p = 0.037; HR, 2.32), also in the stage I-III subgroup (p = 0.046). LGR5 indicated a poor prognosis regarding both PFS (p = 0.007; HR, 1.013) and overall survival (p = 0.045; HR, 1.01). High AGR2/LGR5 was associated with poor PFS (p = 0.014; HR, 2.8) by multivariate analysis. Our findings indicate that the assessment of AGR2 and LGR5 in PB might reflect the presence of circulating tumor cells (CTC) and stem cell like CTC in CRC. Increased AGR2 and LGR5 are associated with poor outcomes.

The presence of tumor cells in the bone marrow (BM) could be relevant to identifying high risk of disease progression and death in gastrointestinal cancer. However, the molecular profile associated with disseminated tumor cells (DTCs) homing to the BM has yet to be defined. MicroRNAs (miRNA) play key roles in cellular processes implicated in cancer. Thus, we investigated in 38 patients with colorectal, gastric or pancreatic cancer whether the presence of BM-DTCs is associated with a specific miRNA tumor profile and analyzed their potential prognostic impact. DTCs were detected by immunocytochemistry and anti-cytokeratin antibodies in 42.1% of the patients. miRNAs were isolated from formalin-fixed, paraffin-embedded tumors. qRT-PCR was used for miRNA profiling. No significant associations were found among DTC detection and miRNA deregulation. Kaplan-Meier curves demonstrated significantly reduced progression-free survival (PFS) and overall survival (OS) in the DTC-positive patients. Although miR-21 was upregulated in 90.6% of the tumors, no associations with outcomes were found. miR-17 and miR-20a (miRNA-17-92 cluster) were upregulated in 33.3 and 42.4%, respectively. Upregulation of both was correlated and found in 30.3%. Univariate analysis shows that increasing values for miR-20a were significantly associated with reduced PFS (HR 1.022; p=0.016) and OS (HR 1.027; p=0.003). In multivariate Cox models, DTC positivity (HR 4.07; p=0.005) and miR-17 overexpression (HR 2.11; p=0.003) were significantly associated with a higher risk of disease progression. The presence of DTCs in the BM (HR 3.98; p=0.010) and a miR-17 overexpression (HR 2.62; p<0.001) were also associated with a risk of death. Our study suggests that the presence of BM-DTCs and the upregulation of the miR-17-92 cluster in tumors are both significant but independent prognostic markers in gastrointestinal cancer patients.

Background: The dynamic regulation of cell-cell adhesions is crucial for developmental processes, including tissue formation, differentiation and motility. Adherens junctions are important components of the junctional complex between cells and are necessary for maintaining cell homeostasis and normal tissue architecture. E-cadherin is the prototype and best-characterized protein member of adherens junctions in mammalian epithelial cells. Regarded as a tumour suppressor, E-cadherin loss is associated with poor prognosis in carcinoma. The E3 ubiquitin-ligase Hakai was the first reported posttranslational regulator of the E-cadherin complex. Hakai specifically targetted E-cadherin for internalization and degradation and thereby lowered epithelial cell-cell contact. Hakai was also implicated in controlling proliferation, and promoted cancer-related gene expression by increasing the binding of RNA-binding protein PSF to RNAs encoding oncogenic proteins. We sought to investigate the possible implication of Hakai in cell-substratum adhesions and invasion in epithelial cells. Methods: Parental MDCK cells and MDCK cells stably overexpressing Hakai were used to analyse cell-substratum adhesion and invasion capabilities. Western blot and immunofluoresecence analyses were performed to assess the roles of Paxillin, FAK and Vinculin in cell-substratum adhesion. The role of the proteasome in controlling cell-substratum adhesion was studied using two proteasome inhibitors, lactacystin and MG132. To study the molecular mechanisms controlling Paxillin expression, MDCK cells expressing E-cadherin shRNA in a tetracycline-inducible manner was employed. Results: Here, we present evidence that implicate Hakai in reducing cell-substratum adhesion and increasing epithelial cell invasion, two hallmark features of cancer progression and metastasis. Paxillin, an important protein component of the cell-matrix adhesion, was completely absent from focal adhesions and focal contacts in Hakai-overexpressing MDCK cells. The expression of Paxillin was found to be regulated by a proteasome-independent mechanism, possibly due to the decreased abundance of E-cadherin. Conclusions: Taken together, these results suggest that Hakai may be involved in two hallmark aspects of tumour progression, the lowering cell-substratum adhesion and the enhancement of cell invasion.