TLR2 and TLR4 in colorectal cancer: relationship to tumor necrosis and markers of systemic inflammation.

In colorectal cancer (CRC), systemic inflammation is associated with poor prognosis, but the underlying mechanisms are not fully characterized. Tumor necrosis may contribute to systemic inflammation by inducing interleukin (IL)-6 signaling, and proinflammatory cytokines such as IL-6 and IL-8, and matrix metalloproteinase (MMP)-8 also are linked to adverse CRC outcomes. Because Toll-like receptors (TLRs) are important mediators of inflammatory responses, we investigated the roles of TLR2 and TLR4 in CRC-associated systemic inflammatory responses, especially tumor necrosis. In 118 patients with CRC, extensive tumor necrosis was associated with low TLR4 expression in tumor cells. Tumor cell TLR4 expression was inversely correlated with serum IL-6 and MMP-8 levels, blood total leukocyte and neutrophil counts, and serum C-reactive protein levels. Tumor cell TLR2 expression was not significantly associated with necrosis or systemic inflammation, but low expression in normal mucosa was linked to high serum MMP-8 and IL-8. These findings indicate that tumor necrosis is associated with low TLR4 expression in cancer cells and that low TLR4 expression correlates with a strong systemic inflammatory response. The low TLR2 expression in normal mucosa and its association with systemic inflammation suggest that the normal mucosa may reflect or contribute to the systemic inflammatory response.

Decreased preoperative serum 25-Hydroxyvitamin D levels in colorectal cancer are associated with systemic inflammation and serrated morphology.

Deficiency of vitamin D is associated with increased risk of several types of cancer including colorectal cancer (CRC). However, factors contributing to low levels of 25-hydroxyvitamin D [25(OH)D] in CRC are not clear. Therefore, in this study serum 25(OH)D levels in 117 CRC patients and 86 controls were analyzed and correlated with the clinicopathological data including morphological subtype (serrated or conventional), quantity of tumor infiltrating immune cells, levels of systemic inflammatory markers, and disease outcome. We found that the patients had lower serum 25(OH)D levels compared to the controls. Interestingly, among the patients mismatch repair deficiency, serrated morphology, and high body mass index associated with lowest serum 25(OH)D levels. In addition, patients operated in summer or autumn had higher serum 25(OH)D levels. Furthermore, serum 25(OH)D levels inversely correlated with several systemic inflammatory markers, e.g. serum C reactive protein, but did not associate with prognosis. Mechanism leading to vitamin D deficiency in these patients are not clear but could be related to the effects of systemic inflammation. Longitudinal studies are warranted to assess vitamin D deficiency as a potential risk factor for serrated colorectal polyps and adenocarcinoma.

The relationships between serum cytokine levels and tumor infiltrating immune cells and their clinical significance in colorectal cancer.

Increased inflammatory cell infiltration correlates to improved survival in colorectal cancer (CRC). Development and progression of CRC is associated with alterations in serum cytokine levels but their significance is not well defined. In this study, we investigated the relationships between the serum levels of 13 cytokines and the densities of eight types of tumor infiltrating inflammatory cells and their impact on disease-free survival (DFS), cancer-specific survival (CSS) and overall survival (OS) in a prospectively recruited group of 147 CRC patients. There were strong positive correlations between the serum concentrations of different cytokines, as well as between the different types of tumor infiltrating immune cells, whereas the associations between serum cytokines and tumor infiltrating immune cells were generally weak. High serum IL-12 levels associated with increased densities of peritumoral CD8(+) T cells, intraepithelial CD3(+) T cells and intratumoral neutrophils, while high serum CCL4 levels associated with increased densities of peritumoral CD68(+) cells. In multivariate survival models, increased infiltration of intraepithelial CD3(+) T cells and increased serum CCL4 associated with improved DFS, whereas higher intratumoral CD83(+) dendritic cell density and increased serum interferon gamma levels associated with improved CSS and OS. Also high density of peritumoral CD3(+) T cells associated with improved CSS. In conclusion, serum cytokines and tumor infiltrating immune cells in CRC represent entities with high intragroup correlations but relatively weak intergroup correlations. The results suggest that tumor infiltrating CD3(+) T cells, CD83(+) dendritic cells, serum CCL4 and serum interferon gamma represent relevant markers of disease outcome.

Frequent mutations of KRAS in addition to BRAF in colorectal serrated adenocarcinoma.

AIMS: To define the occurrence of KRAS and BRAF mutations, microsatellite instability (MSI), and MGMT and hMLH1 methylation and expression in colorectal serrated adenocarcinoma. METHODS AND RESULTS: KRAS codon 12/13 and 59/61 and BRAF V600E mutations, MSI, and MGMT and hMLH1 methylation and expression in 42 serrated adenocarcinomas and 17 serrated adenomas were compared with those in 59 non-serrated colorectal carcinomas (CRCs) and nine adenomas. KRAS and BRAF mutations were observed in 45% and 33% of serrated adenocarcinomas and in 27% and 0% of non-serrated CRCs (P < 0.001). The KRAS c12G→A transition was the predominant type of mutation in serrated adenocarcinomas. Forty-two per cent of BRAF-mutated serrated adenocarcinomas showed high-level MSI (MSI-H) (P = 0.075), 100% showed hMLH1 methylation (P = 0.001) and 90.9% showed MGMT methylation (P = 0.019). Fifty-six per cent of serrated adenocarcinomas with microsatellite stability/low-level microsatellite instability harboured KRAS mutations. In non-serrated cancers, KRAS mutations were not associated with MSI status. CONCLUSIONS: A high combined mutation rate (79-82%) of KRAS and BRAF in serrated adenomas and adenocarcinomas indicates that mitogen-activated protein kinase activation is a crucial part of the serrated pathway. BRAF mutations are specific for serrated adenocarcinoma and identify a subset of serrated adenocarcinomas with gene methylation and a tendency for MSI-H. A high frequency of KRAS mutations in serrated adenocarcinomas suggests that a significant proportion of KRAS-mutated CRCs originate from serrated precursors, thus challenging the traditional model of Vogelstein.

Downregulation of the hedgehog receptor PTCH1 in colorectal serrated adenocarcinomas is not caused by PTCH1 mutations.

Colorectal serrated adenocarcinoma forms about 15-20% of colorectal carcinomas. We have previously shown that downregulation of PTCH1 is distinctive for this type of colorectal cancer. In several other tumor types, somatic inactivating PTCH1 mutations have been shown to lead to aberrant Hedgehog signaling, but in colorectal cancer the role of PTCH1 mutations has not been thoroughly studied. Here, we have analyzed the mutation status of PTCH1 in a series of 33 colorectal serrated adenocarcinomas by sequencing all 23 coding exons. We detected 11 previously known SNPs and eight new alterations. The latter included five synonymous changes and two previously unknown missense variations, somatic M319V, and germline V1231A. V1231A was also present in population controls and likely represents polymorphism. The somatic M319V variant does not appear to be an attractive candidate for a disease-associated mutation because in silico analyses did not support the pathogenic nature of the change. A somatic, intronic 1-bp deletion was detected in a short poly(T) stretch in two microsatellite unstable tumors. None of the three changes had predicted effect on splicing when analyzed in silico. Our results did not reveal any clearly deleterious inactivating PTCH1 mutations in our collection of colorectal serrated adenocarcinomas. This suggests that other mechanisms are involved in the observed downregulation of the PTCH1 gene. These might include, e.g., constantly active MAPK signaling by KRAS or BRAF mutations or silencing of PTCH1 by hypermethylation, and further studies are needed to reveal these mechanisms.