New molecular staging with G-factors (VEGF-C and Reg IV) by supplementing TNM classification in colorectal cancers

Regenerating gene 4 promotes chemoresistance of colorectal cancer by affecting lipid droplet synthesis and assembly

BACKGROUND

Regenerating gene 4 (REG4) has been proved to be carcinogenic in some cancers, but its manifestation and possible carcinogenic mechanisms in colorectal cancer (CRC) have not yet been elucidated. Our previous study found that the drug resistance of CRC cells may be closely linked to their fat metabolism.

AIM

To explore the role of REG4 in CRC and its association with lipid droplet formation and chemoresistance.

METHODS

We conducted a meta-analysis and bioinformatics and pathological analyses of REG4 expression in CRC. The effects of REG4 on the phenotypes and related protein expression were also investigated in CRC cells. We detected the impacts of REG4 on the chemoresistance and lipid droplet formation in CRC cells. Finally, we analyzed how REG4 regulated the transcription and proteasomal degradation of lipogenic enzymes in CRC cells.

RESULTS

Compared to normal mucosa, REG4 mRNA expression was high in CRC (P < 0.05) but protein expression was low. An inverse correlation existed between lymph node and distant metastases, tumor-node-metastasis staging or short overall survival and REG4 mRNA overexpression (P < 0.05), but vice versa for REG4 protein expression. REG4-related genes included: Chemokine activity; taste receptors; protein-DNA and DNA packing complexes; nucleosomes and chromatin; generation of second messenger molecules; programmed cell death signals; epigenetic regulation and DNA methylation; transcription repression and activation by DNA binding; insulin signaling pathway; sugar metabolism and transfer; and neurotransmitter receptors (P < 0.05). REG4 exposure or overexpression promoted proliferation, antiapoptosis, migration, and invasion of DLD-1 cells in an autocrine or paracrine manner by activating the epidermal growth factor receptor-phosphoinositide 3-kinase-Akt-nuclear factor-κB pathway. REG4 was involved in chemoresistance not through de novo lipogenesis, but lipid droplet assembly. REG4 inhibited the transcription of acetyl-CoA carboxylase 1 (ACC1) and ATP-citrate lyase (ACLY) by disassociating the complex formation of anti-acetyl (AC)-acetyl-histone 3-AC-histone 4-inhibitor of growth protein-5-si histone deacetylase;-sterol-regulatory element binding protein 1 in their promoters and induced proteasomal degradation of ACC1 or ACLY.

CONCLUSION

REG4 may be involved in chemoresistance through lipid droplet assembly. REG4 reduces expression of de novo lipid synthesis key enzymes by inhibiting transcription and promoting ubiquitination-mediated proteasomal degradation.

The Clinical Significance and Mechanisms of REG4 in Human Cancers

Regenerating islet-derived type 4 (REG4), a member of the calcium-dependent lectin gene superfamily, is abnormally expressed in various cancers, such as colorectal, gastric, gallbladder, pancreatic, ovarian, prostate, and lung cancer. REG4 is associated with a relatively unfavorable prognosis and clinicopathologic features in cancers, including advanced tumor and nodal stage, histological differentiation, and liver and peritoneal metastasis. Moreover, REG4-positive cancer cells show more frequent resistance to chemoradiotherapy, especially 5-FU-based chemotherapy. REG4 participates in many aspects of carcinogenesis, including cell proliferation, apoptosis, cell cycle, invasion, metastasis, and drug resistance. The underlying mechanisms are complex and involve a series of signaling mediators and multiple pathways. Thus, REG4 may be a potential diagnostic and prognostic biomarker as well as a candidate therapeutic target in cancer patients. In this review, we systematically summarize the advances about the clinical significance, biological functions, and mechanisms underlying REG4 in cancer to provide new directions for future cancer research.

Prognostic Implications of Novel Gene Signatures in Gastric Cancer Microenvironment

Background

Increasing studies have shown the important clinical role of immune and stromal cells in gastric cancer microenvironment. Based on information of immune and stromal cells in The Cancer Genome Atlas, this study aimed to construct a prognostic risk assessment model for gastric cancer.

Material/Methods

Based on the immune/structural scores, differentially expressed genes (DEGs) were filtered and analyzed. Afterwards, DEGs associated with prognosis were screened and the risk assessment model was constructed in the training set. Moreover, the validity of the model was verified both in the testing set and the overall sample.

Results

In this study, patients were divided into high-score and low-score groups based on immune/stromal score, and 919 DEGs were identified. By applying least absolute shrinkage and selection operator (LASSO) and Cox analysis, 10 mRNAs were selected to form a prognostic risk assessment model, risk score=(0.294*SLC17A9) + (−0.477*FERMT3) + (0.866*NRP1) + (0.350*MMRN1) + (0.381*RNASE1) + (0.189*TRIB3) + (0.230*PGAP3) + (0.087*MAGEA3) + (0.182*TACR2) + (0.368*CYP51A1). In the training set, the low-risk group divided by the model was found to have better overall survival, and the prediction efficiency of the model was demonstrated to be good. Multivariate Cox analysis indicated that the model could work as a prognostic factor independently. Similar results were shown in the testing group and overall patients cohort group. Finally, the risk assessment model and other clinical variables were integrated to construct a nomogram.

Conclusions

In general, this study constructs a prognostic risk assessment model for gastric cancer, which could improve the prognosis stratification of patients combined with other clinical indicators.

Prognostic significance of VEGF-C immunohistochemical expression in colorectal cancer: A meta-analysis

BACKGROUND

We sought to comprehensively summarize available evidence for the use of VEGF-C protein to evaluate the clinicopathological and prognostic role of VEGF-C in colorectal cancer.

METHODS

Electronic databases from inception to February 2016 were used to search without language restrictions for original articles. A meta-analysis was undertaken to assess the relationship between VEGF-C expression and overall survival (OS) in colorectal cancer.

RESULTS

Twenty-seven studies were included in the final meta-analysis. We aggregated 13 trials (n=1.428 patients) that evaluated the correlation between OS and VEGF-C overexpression. Statistics were performed for OS (HR=1.95; 95%CI=1.31-2.92, P=0.007). When the studies were stratified by the pathological variables, including T stage (n=383 patients; OR=1.79; 95%CI=1.14-2.81), lymph node metastasis (n=3212 patients; OR=4.21; 95%CI=3.49-5.08), M stage (n=1106 patients; OR=4.46; 95%CI=2.96-6.70), vascular invasion(n=1471 patients; OR=2.18; 95%CI=1.65-2.88), lymph invasion (n=831 patients; OR=3.95; 95%CI=2.80-5.56), histo-differentiation (n=1695 patients; OR=1.34; 95%CI=1.00-1.79) and Duke's stage(n=778 patients; OR=4.90; 95%CI=3.55-6.75), TNM stage (n=808 patients; OR=1.73; 95%CI=1.18-2.54) provided critical and comprehensive prognostic information.

CONCLUSION

Our results demonstrated that VEGF-C overexpression was associated with OS in colorectal cancer.

Olfactomedin-4 is a candidate biomarker of solid gastric, colorectal, pancreatic, head and neck, and prostate cancers

Olfactomedin-4 (OLFM4, OLM4) is a 72 kDa secreted glycoprotein belonging to the olfactomedin family. The OLFM4 gene expression is regulated by the transcription factors NF-kappa B and AP-1, and the OLM4 functions are poorly understood. OLM4 has been described as being able to interact with cell surface proteins such as lectins and concanavalin-A suggesting that one function of OLM4 is to regulate cell adhesion and migration. OLM4 is a marker for intestinal stem cells and is expressed at the bottom of the intestinal crypts. Expression of OLM4 during tumor development showed that OLM4 expression is increased in the early stages of tumor initiation. As OLM4 is a secreted protein, it is a prime candidate for biomarker research for tumor detection or progression. Levels of circulating OLM4 were significantly higher in patients with gastric, colorectal, and pancreatic cancers than in healthy subjects.