The prognostic effect of tumor-associated macrophages in stage I-III colorectal cancer depends on T cell infiltration.

BACKGROUND: Tumor-associated macrophages (TAMs) are associated with unfavorable patient prognosis in many cancer types. However, TAMs are a heterogeneous cell population and subsets have been shown to activate tumor-infiltrating T cells and confer a good patient prognosis. Data on the prognostic value of TAMs in colorectal cancer are conflicting. We investigated the prognostic effect of TAMs in relation to tumor-infiltrating T cells in colorectal cancers. METHODS: The TAM markers CD68 and CD163 were analyzed by multiplex fluorescence immunohistochemistry and digital image analysis on tissue microarrays of 1720 primary colorectal cancers. TAM density in the tumor stroma was scored in relation to T cell density (stromal CD3+ and epithelial CD8+ cells) and analyzed in Cox proportional hazards models of 5-year relapse-free survival. Multivariable survival models included clinicopathological factors, MSI status and BRAFV600E mutation status. RESULTS: High TAM density was associated with a favorable 5-year relapse-free survival in a multivariable model of patients with stage I-III tumors (p = 0.004, hazard ratio 0.94, 95% confidence interval 0.90-0.98). However, the prognostic effect was dependent on tumoral T-cell density. High TAM density was associated with a good prognosis in patients who also had high T-cell levels in their tumors, while high TAM density was associated with poorer prognosis in patients with low T-cell levels (pinteraction = 0.0006). This prognostic heterogeneity was found for microsatellite stable tumors separately. CONCLUSIONS: This study supported a phenotypic heterogeneity of TAMs in colorectal cancer, and showed that combined tumor immunophenotyping of multiple immune cell types improved the prediction of patient prognosis.

Epigenetic disruption of miR-130a promotes prostate cancer by targeting SEC23B and DEPDC1.

MicroRNAs (miRNAs) are small, non-coding RNAs that mediate post-transcriptional gene silencing, fine tuning gene expression. In an initial screen, miRNAs were found to be globally down-regulated in prostate cancer (PCa) cell lines and primary tumours. Exposure of PCa cell lines to a demethylating agent, 5-Aza-CdR resulted in an increase in the expression levels of miRNAs in general. Using stringent filtering criteria miR-130a was identified as the most promising candidate and selected for validation analyses in our patient series. Down-regulation of miR-130a was associated with promoter hypermethylation. MiR-130a methylation levels discriminated PCa from non-malignant tissues (AUC = 0.956), and urine samples revealed high specificity for non-invasive detection of patients with PCa (AUC = 0.89). Additionally, repressive histone marks were also found in the promoter of miR-130a. Over-expression of miR-130a in PCa cells reduced cell viability and invasion capability, and increased apoptosis. Putative targets of miR-130a were assessed by microarray expression profiling and DEPD1C and SEC23B were selected for validation. Silencing of both genes resembled the effect of over-expressing miR-130a in PCa cells. Our data indicate that miR-130a is an epigenetically regulated miRNA involved in regulation of key molecular and phenotypic features of prostate carcinogenesis, acting as a tumour suppressor miRNA.

The novel colorectal cancer biomarkers CDO1, ZSCAN18 and ZNF331 are frequently methylated across gastrointestinal cancers.

We have previously shown that gastrointestinal cancers display similar epigenetic aberrations. In a recent study, we identified frequently methylated genes for cholangiocarcinoma (CDO1, DCLK1, SFRP1 and ZSCAN18), where one of these genes, DCLK1, was also confirmed to be highly methylated in colorectal cancer. The aim of the present study was to determine whether these four genes, in addition to one gene found to be methylated in colon cancer cell lines (ZNF331), are commonly methylated across gastrointestinal malignancies, as well as explore their role as potential biomarkers. Quantitative methylation specific PCR (qMSP) of colorectal cancer (n=164) and normal colorectal mucosa (n=106) samples showed that all genes were frequently methylated in colorectal cancer (71-92%) with little or no methylation in normal mucosa (0-3%). Methylation of minimum two of these five genes identified 95% of the tumors with a specificity of 98%, and an area under the receiver operating characteristics curve (AUC) of 0.98. For gastric (n=25) and pancreatic (n=20) cancer, the same panel detected 92% and 90% of the tumors, respectively. Seventy-four cancer cell lines were further analyzed by qMSP and real time RT-PCR. In addition to the previously reported DCLK1, a high negative correlation between promoter DNA methylation and gene expression was observed for CDO1, ZNF331 and ZSCAN18. In conclusion, the high methylation frequency of these genes in colorectal- as well as in gastric-, pancreatic- and bile duct cancer confirmed an epigenetic similarity between gastrointestinal cancer types, and simultaneously demonstrated their potential as biomarkers, particularly for colorectal cancer detection.