Evaluation of REG4 for early diagnosis and prognosis of gastric cancer

REG4 promotes the proliferation and anti-apoptosis of cancer

Regenerating islet-derived 4 (REG4) gene was discovered by high-throughput sequencing of ulcerative colitis cDNA libraries. REG4 is involved in infection and inflammation by enhancing macrophage polarization to M2, via activation of epidermal growth factor receptor (EGFR)/Akt/cAMP-responsive element binding and the killing inflammatory Escherichia coli, and closely linked to tumorigenesis. Its expression was transcriptionally activated by caudal type homeobox 2, GATA binding protein 6, GLI family zinc finger 1, SRY-box transcription factor 9, CD44 intracytoplasmic domain, activating transcription factor 2, and specificity protein 1, and translationally activated by miR-24. REG4 can interact with transmembrane CD44, G protein-coupled receptor 37, mannan and heparin on cancer cells. Its overexpression was observed in gastric, colorectal, pancreatic, gallbladder, ovarian and urothelial cancers, and is closely linked to their aggressive behaviors and a poor prognosis. Additionally, REG4 expression and recombinant REG4 aggravated such cellular phenotypes as tumorigenesis, proliferation, anti-apoptosis, chemoradioresistance, migration, invasion, peritoneal dissemination, tumor growth, and cancer stemness via EGFR/Akt/activator protein-1 and Akt/glycogen synthase kinase three β/β-catenin/transcription factor 4 pathways. Sorted REG4-positive deep crypt secretory cells promote organoid formation of single Lgr5 (+) colon stem cells by Notch inhibition and Wnt activation. Histologically, REG4 protein is specifically expressed in neuroendocrine tumors and signet ring cell carcinomas of the gastrointestinal tract, pancreas, ovary, and lung. It might support the histogenesis of gastric intestinal–metaplasia–globoid dysplasia–signet ring cell carcinoma. In this review, we summarized the structure, biological functions, and effects of REG4 on inflammation and cancer. We conclude that REG4 may be employed as a biomarker of tumorigenesis, subsequent progression and poor prognosis of cancer, and may be a useful target for gene therapy.

A lncRNA signature of tumor-infiltrating macrophages is associated with prognosis and tumor immunity in lung adenocarcinoma

Accumulating evidence suggests that long noncoding RNAs (lncRNAs) play a critical role in regulating cancer immunity and the tumor microenvironment. Tumor-infiltrating macrophages are one of the most abundant constituents of many tumors. However, the functions and clinical significance of lncRNAs in tumor-associated macrophages have not been systematically elucidated. In this study, we analyzed the tumor immune microenvironment and lncRNA expression level differences based on The Cancer Genome Atlas (TCGA) and immune cell transcriptome profiles using lung adenocarcinoma microarray datasets GSE3141, GSE51210, GSE37745, and the RNA sequencing data of GSE81089. We then identified a macrophage infiltration-related lncRNA signature (MILnc) including LINC00240, MCF2L-AS1, SFTA3, MIR497HG, FAM215A, UCA1, MIR155HG, and TLRB-AS1 from a list of 147 macrophage-specific lncRNAs. The MILnc was capable of predicting overall survival differences in TCGA and several external validation datasets with a favorable performance. Functional analysis revealed that MILnc was associated with tumor progression and negatively correlated with immune checkpoints. Additionally, MILnc was positively correlated with tumor mutational burden and could predict the immunotherapy response of patients receiving anti-PD-1 or anti-CTLA4 therapy. In summary, our study highlighted the value of MILnc, which revealed the immune environment status and immunotherapy response of lung adenocarcinoma. A robust and powerful MILnc risk model could aid exploration of treatment decisions and mechanisms of macrophage-infiltrating lncRNAs.

Reg4 Interacts with CD44 to Regulate Proliferation and Stemness of Colorectal and Pancreatic Cancer Cells

Regenerating Gene 4 (Reg4) is highly upregulated in gastrointestinal (GI) malignancies including colorectal and pancreatic cancers. Numerous studies demonstrated an association between higher Reg4 expression and tumor aggressiveness, intrinsic resistance to apoptotic death, and poor outcomes from GI malignancies. However, the precise receptor and underlying signaling mechanism have remained unknown. Although we previously reported a Reg4-mediated induction of EGFR activity in colorectal cancer cells, a direct interaction between Reg4 and EGFR was not observed. This study is focused on identifying the cell surface binding partner of Reg4 and dissecting its role in colorectal cancer and pancreatic cancer growth and stem cell survival. In vitro models of human colorectal cancer and pancreatic cancer were used to evaluate the results. Results of this study find: (i) Reg4 interacts with CD44, a transmembrane protein expressed by a population of colorectal cancer and pancreatic cancer cells; (ii) Reg4 activates regulated intramembrane proteolysis of CD44 resulting in γ-secretase-mediated cleavage and release of the CD44 intracytoplasmic domain (CD44ICD) that functions as a transcriptional activator of D-type cyclins involved in the regulation of cancer cell proliferation and Klf4 and Sox2 expression involved in regulating pluripotency of cancer stem cells; and (iii) Reg4 significantly increases colorectal cancer and pancreatic cancer cell proliferation and their clonogenic potential in stem cell assays.

IMPLICATIONS

These results suggest that pro-proliferative and pro-stemness effects of Reg4 are mediated through γ-secretase-mediated CD44/CD44ICD signaling, hence strategies to disrupt Reg4-CD44-γ-secretase-CD44ICD signaling axis may increase cancer cell susceptibility to chemo- and radiotherapeutics.

The Potential Role of REG Family Proteins in Inflammatory and Inflammation-Associated Diseases of the Gastrointestinal Tract

Regenerating gene (REG) family proteins serve as multifunctional secretory molecules with trophic, antiapoptotic, anti-inflammatory, antimicrobial and probably immuno-regulatory effects. Since their discovery, accumulating evidence has clarified the potential roles of the REG family in the occurrence, progression and development of a wide range of inflammatory and inflammation-associated diseases of the gastrointestinal (GI) tract. However, significant gaps still exist due to the undefined nature of certain receptors, regulatory signaling pathways and possible interactions among distinct Reg members. In this narrative review, we first describe the structural features, distribution pattern and purported regulatory mechanisms of REG family proteins. Furthermore, we summarize the established and proposed roles of REG proteins in the pathogenesis of various inflammation-associated pathologies of the GI tract and the body as a whole, focusing particularly on carcinogenesis in the ulcerative colitis—colitic cancer sequence and gastric cancer. Finally, the clinical relevance of REG products in the context of diagnosis, treatment and prognostication are also discussed in detail. The current evidence suggests a need to better understanding the versatile roles of Reg family proteins in the pathogenesis of inflammatory-associated diseases, and their broadened future usage as therapeutic targets and prognostic biomarkers is anticipated.

CDX2 and Reg IV expression and correlation in gastric cancer

Background

Ectopic expression of CDX2 is associated with the development and progression of gastric cancer. Previous studies showed that CDX2 may be an upstream regulator of Reg IV expression in gastric cancer, and our previous report showed that Reg IV upregulated SOX9 expression and enhanced cell migration and invasion in gastric cancer cells. However, the regulatory roles of CDX2 have not been clarified in gastric cancer, and the correlation between CDX2 and Reg IV requires further study.

Methods

CDX2 and Reg IV were examined in gastric cancer specimens and paired adjacent tissues via real-time PCR and immunohistochemistry (IHC). The association between CDX2 and Reg IV was assessed using the χ²-test and Spearman’s rank correlation. To verify their relationship, knockdown and exogenous expression of CDX2 or Reg IV were performed in AGS and MKN-45 gastric cancer cells, and their expression was subsequently analyzed via a real-time PCR and western blotting. Wound-healing and Transwell assays were used to examine migration and invasion in AGS and MKN-45 cells following CDX2 silencing or overexpression.

Results

A positive correlation was observed between CDX2 and Reg IV expression at the mRNA and protein levels in gastric cancer tissues. CDX2 silencing significantly downregulated Reg IV expression, and CDX2 overexpression significantly upregulated Reg IV expression in AGS and MKN-45 cells. Neither Reg IV silencing nor overexpression had any effect on CDX2 protein expression in AGS or MKN-45 cells, even though both affected the expression of CDX2 mRNA. Functionally, CDX2 silencing significantly inhibited cell migration and invasion, and CDX2 overexpression significantly promoted cell migration and invasion in AGS and MKN-45 cells.

Conclusions

Our findings demonstrate that CDX2 expression was positively correlated with that of Reg IV in gastric cancer, and CDX2 promoted cell migration and invasion through upregulation of Reg IV expression in AGS and MKN-45 cells.

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.

Single-chain Antibody Against Reg4 Suppresses Gastric Cancer Cell Growth and Enhances 5-FU-induced Cell Death in vitro

BACKGROUND

Regenerating islet-derived gene family member 4 (Reg4), a well-investigated growth factor in the regenerative pancreas, has recently been reported to be highly associated with a majority of gastrointestinal cancers. Pathological hyper-expression or artificial over-expression of Reg4 causes acceleration of tumor growth, migration, and resistance to chemotherapeutic 5-Fluorouracil (5-FU). Until now, no method has been successfully established for eliminating the effects of Reg4 protein.

METHODS

This study reports the production of an engineered immunoglobin, a single-chain variable fragment (scFv-Reg4), to specifically bind Reg4 and block the bioactivity. The complementary-determining regions (CDRs) against Reg4 were assigned using MOE and ZDOCK servers. The binding affinity (KD) was determined by bio-layer interferometry (BLI). MKN45 and AGS cell proliferation was determined by Thiazolyl blue tetrazolium bromide (MTT) method and the cell apoptosis was detected by flow cytometry assay.

RESULTS

The KD of scFv-Reg4 to Reg4 was determined to be 1.91×10-8. In MKN45 and AGS cell lines, scFv- Reg4 depressed Reg4-stimulated cell proliferation and the inhibitory rates were 27.7±1.5% and 17.3±2.6%, respectively. Furthermore, scFv significantly enhanced 5-FU-induced cell death, from 23.0±1.0% to 28.4±1.2% in MKN45 and 28.2±0.7% to 36.6±0.6% in AGS cells. Treatment with scFv alone could lyse cancer cells to a certain extent, but no significance has been observed.

CONCLUSION

The single-chain antibody (scFv-Reg4) significantly inhibited gastric cancer cell proliferation and synergistically enhanced the lethal effect of 5-FU. Thus, traditional chemo-/radio- therapeutics supplemented with scFv-Reg4 may provide advances in the strategy for gastrointestinal cancer treatment.

Four Decades After the Discovery of Regenerating Islet-Derived (Reg) Proteins: Current Understanding and Challenges

Regenerating islet-derived (Reg) proteins have emerged as multifunctional agents with pro-proliferative, anti-apoptotic, differentiation-inducing and bactericidal properties. Over the last 40 years since first discovered, Reg proteins have been implicated in a gamut of maladies including diabetes, various types of cancer of the digestive tract, and Alzheimer disease. Surprisingly though, a consensus is still absent on the regulation of their expression, and molecular underpinning of their function. Here, we provide a critical appraisal of recent findings in the field of Reg protein biology. Specifically, the structural characteristics are reviewed particularly in connection with established or purported functions of different members of the Reg family. Moreover, Reg expression patterns in different tissues both under normal and pathophysiological conditions are summarized. Putative receptors and cascades reported to relay Reg signaling inciting cellular responses are presented aiming at a better appreciation of the biological activities of the distinct Reg moieties. Challenges are also discussed that have hampered thus far the rapid progress in this field such as the use of non-standard nomenclature for Reg molecules among various research groups, the existence of multiple Reg members with significant degree of homology and possibly compensatory modes of action, and the need for common assays with robust readouts of Reg activity. Coordinated research is warranted going forward, given that several research groups have independently linked Reg proteins to diseased states and raised the possibility that these biomolecules can serve as therapeutic targets and biomarkers.

The correlation of NLRC3 expression with the progression and prognosis of hepatocellular carcinoma

NLRC3 is a member of the nucleotide-binding domain and leucine-rich repeat (NLR) family protein that plays a role in inflammation and immunity. Although chronic inflammation has been identified as a hallmark of cancer, NLRC3 expression correlation with the development and prognosis of hepatocellular carcinoma (HCC) is unclear. In the present study, we first used Oncomine and OncoLnc database to determine the clinical significance of NLRC3 in HCC. Then we performed quantitative real-time polymerase chain reaction, Western blot, and immunohistochemical staining (IHC) and analyzed the correlation between NLRC3 expression and clinicopathological features of HCC in a Chinese population. We found that high levels of NLRC3 messenger RNA (mRNA) correlated with a favorable clinical outcome; furthermore, expression of NLRC3 was significantly reduced in the cancer tissue in patients compared with noncancerous hepatic tissues. NLRC3 reduction was correlated with Edmondson grade and metastasis. Kaplan-Meier survival analysis revealed that HCC patients with high expression of NLRC3 have a more favorable prognosis compared with those with low expression of NLRC3. We then used short hairpin RNA to knock down NLRC3 expression in HCC cell lines and evaluated its effect on cell proliferation and apoptosis. Suppression of NLRC3 expression promoted cell proliferation and inhibited apoptosis in vitro. Genomic analysis of the OncoLnc database also showed that NLRC3 mRNA level was directly correlated with mRNA levels of inflammasome components caspase-1, IL-1β, and IL-18. Based on our present study, down-regulated expression of NLRC3 may play an important role in cancer progression and prognosis of HCC by acting as a tumor suppressor.

Prognostic and diagnostic value of REG4 serum and tissue expression in pancreatic ductal adenocarcinoma

Expression of regenerating islet-derived protein 4 (REG4), a secretory protein involved in cell differentiation and proliferation, is upregulated in inflammatory bowel diseases and in many gastrointestinal malignancies. The prognostic significance of its expression in pancreatic ductal adenocarcinoma is unknown. Our aim was to investigate tumor tissue and serum REG4 expression in pancreatic ductal adenocarcinoma patients. We also evaluated as a control the diagnostic value of serum REG4 level in patients with chronic pancreatitis. Immunohistochemical expression of REG4 was evaluated in 154 surgical specimens and serum REG4 level in 130 samples from pancreatic ductal adenocarcinoma patients treated at Helsinki University Hospital, Finland, in 2000-2011. REG4 tissue and serum expression was assessed in relation to clinicopathological parameters and patient survival. A chronic pancreatitis control group comprised 34 patients who underwent pancreatic resection because of suspicion of malignancy. Significant survival differences were detectable in subgroups: in tumor stages IA-IIA, high serum REG4 level predicted worse survival (p=0.046). In patients with grade I tumor, positive tissue REG4 expression predicted better survival (p=0.006). In multivariate analysis, neither tissue nor serum REG4 expression was independent prognostic factors. Serum REG4 levels were higher in pancreatic ductal adenocarcinoma than in chronic pancreatitis (p=0.002), with diagnostic sensitivity of 45% and specificity of 91%. In logistic regression analysis, a multivariate model with REG4, CA19-9, and age provided sensitivity of 82% and specificity of 79%. REG4 tissue expression is a prognostic marker in subgroups of pancreatic ductal adenocarcinoma patients. Serum REG4 level might be useful in differential diagnosis between pancreatic ductal adenocarcinoma and chronic pancreatitis.

CEACAM6 is a prognostic biomarker and potential therapeutic target for gastric carcinoma

This study aims to investigate the prognostic power of carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) in gastric cancer (GC) and its potential role in cancer development and progression. Data mining results show that CEACAM6 is overexpressed in gastric cancer and is correlated with lymph node metastasis. Subsequently, immunohistochemical staining was performed to determine CEACAM6 protein levels in paraffin gastric tumor specimens. Real-time reverse-transcription-polymerase chain reaction (RT-PCR) was conducted to detect CEACAM6 mRNA levels in fresh GC samples. CEACAM6 protein and mRNA levels were significantly up regulated in GC compared with paired normal mucosa. The IHC staining intensity of CEACAM6 was positively correlated with tumor size, Lauren's classification, vascular invasion, lymph node metastasis, distant metastasis, and TNM stage. CEACAM6 expression was inversely correlated with the five-year survival rate of GC patients. Cox multivariate analysis results demonstrated that the overall survival was independently correlated with CEACAM6 expression. A significant association was observed between CEACAM6 and distant metastases. Network analysis of downstream gene signatures revealed several hub genes such as SRC and DNM1L etc. which may mediating tumor promoting functions of CEACAM6. Further data mining discovered that Tamoxifen etc. could be therapeutic alternatives for gastric patients with CEACAM6 overexpression. Collectively, CEACAM6 overexpression is a common characteristic of GC and is associated with poor 5 year survival rate in GC. Besides, potential molecular mechanisms and treatment options were also provided.

Recombinant Reg3β protein protects against streptozotocin-induced β-cell damage and diabetes

Regenerating genes (Reg) have been found during the search for factors involved in pancreatic islet regeneration. Our recent study discovered that pancreatic β-cell-specific overexpression of Reg3β protects against streptozotocin (Stz) -induced diabetes in mice. To investigate its potential roles in the treatment of diabetes, we produced a recombinant Reg3β protein and provided evidence that it is active in promoting islet β-cell survival against Stz- triggered cell death. Though ineffective in alleviating preexisting diabetes, pretreatment of recombinant Reg3β was capable of minimizing the Stz-induced hyperglycemia and weight loss, by preserving serum and pancreatic insulin levels, and islet β-cell mass. No obvious changes were observed in the rate of cell proliferation and hypertrophy in α- or acinar-cells after treatment with recombinant Reg3β. The underlying mechanism of Reg3β-mediated protection seems to involve Akt activation which upregulates Bcl-2 and Bcl-xL levels and consequently promotes cell survival.

miR-203 is a predictive biomarker for colorectal cancer and its expression is associated with BIRC5

The purpose of this study was to explore the role of miR-203 in colorectal cancer (CRC) and evaluate the correlation between miR-203 and BIRC5. The expressions of miR-203 in the tissues of 122 CRC patients (with non-tumor tissues as controls) and those from 30 healthy donors were detected by TaqMan® MicroRNA assay. BIRC5s expressions in CRC and non-tumor tissues were detected by immunohistochemistry. Significantly less miR-203 was expressed in CRC tissues (P < 0.05) than in non-tumor tissues. Furthermore, low expression level of miR-203 was correlated with distant metastasis (DM), lymph node metastasis (LNM), and TNM stage (P < 0.05), but there were no significant differences between tumor size or gender. The positive expression rates of BIRC5 in CRC and non-tumor tissues were 73.77 % (90/122) and 30.32 % (37/122), respectively. The expression intensity of BIRC5 in CRC was significantly higher than that of non-tumor tissues (P < 0.05). It was significantly correlated with DM, LNM, and TNM stage (P < 0.05). Finally, miR-203 expression was negatively associated with that of BIRC5 (r = -0.8150, P < 0.05). In conclusion, miR-203 was down-regulated in CRC tissues and involved in the onset and progression of CRC. The expressions of miR-203 and BIRC5 in CRC were significantly negatively correlated, suggesting that BIRC5 may be regulated by miR-203. miR-203 is a potential suppressor and predictive biomarker for CRC.

REG4 promotes peritoneal metastasis of gastric cancer through GPR37

Being the major reason of recurrence and death after surgery, peritoneal metastasis of gastric cancer dooms the prognosis of advanced gastric cancer patients. Regenerating islet-derived family, member 4 (REG4) is believed to promote peritoneal metastasis, however, its mechanism is still a moot point at present. In the present study, we show that high expression of REG4 correlates with advanced stage and poor survival prognosis for gastric cancer patients. REG4 overexpression significantly enhances peritoneal metastasis by increasing adhesion ability. Moreover, SP1 is proved to be a transcription factor of REG4 and induce REG4 expression upon TGF-alpha stimulation. Also, G protein-coupled receptor 37 (GPR37) is identified to be in the same complex of REG4, which mediates REG4's signal transduction and promotes peritoneal metastasis of gastric cancer cell. Interestingly, we also discover a positive feedback loop triggered by REG4, amplifying itself through EGFR transactivation, consisting of GPR37, ADAM17, TGF-alpha, EGFR, SP1 and REG4. In conclusion, REG4 promotes peritoneal metastasis of gastric cancer through GPR37 and triggers a positive feedback loop.

The pancreatic cancer secreted REG4 promotes macrophage polarization to M2 through EGFR/AKT/CREB pathway

In the periphery of pancreatic ductal adenocarcinoma (PDAC), high accumulation of tumor-associated macrophages (TAMs), which exhibit M2 phenotype, has been shown to be correlated with extra-pancreatic invasion, lymph vessel invasion, lymph node involvement and shortened survival time. However, mechanisms by which tumor cells educate and reprogram TAMs remain largely unclear. The phenotype of TAMs in PDAC tissues was confirmed by immunofluoresence and confocal microscopy. Human CD14+ monocytes were incubated with recombinant human REG4 (rREG4) before being stimulated with LPS and IL-10 and IL-6 were measured with ELISA. A panel of M1 and M2 genes were measured by quantitative real-time PCR. Panc1, AsPC1 and BxPC3 cells were cultured in the conditioned medium (CM) and treated with REG4. The macrophages were infected with CREB shRNA or cultured by the CM of Panc1 cells infected with REG4 shRNA. The expression of CD163, CD206 and REG4 and the phosphorylation levels of epidermal growth factor receptor (EGFR), AKT and cAMP response element-binding protein (CREB) in cells were assessed with western blotting. Cell proliferation and invasiveness were also assessed. The rREG4 or the conditioned medium of Panc1 cells which secreted REG4 induced the polarization macrophages to M2 phenotype. Treatment of human macrophages with REG4 resulted in phosphorylation of EGFR, AKT and CREB. The latter was responsible for REG4-mediated macrophage polarization to M2. The conditioned medium of macrophages treated with rREG4 promoted the proliferation and invasion of pancreatic cancer cell lines. REG4, overexpressed in PDAC and secreted by cancer cells, promoted macrophage polarization to M2, through at least in part, activation of ERK1/2 and CREB and changed the microenvironment to facilitate cancer growth and metastasis.

Identification of peptide regions of SERPINA1 and ENOSF1 and their protein expression as potential serum biomarkers for gastric cancer

This study aimed to detect potential serum biomarkers for gastric cancer. In the present study, we used magnetic bead-based purification and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry to detect potential serum markers in 70 gastric cancer (GC) patients compared with 72 healthy controls. On average, up to 81 peaks, of which 11 were significantly different m/z peaks (fold change >1.5; P < 0.001, Wilcoxon rank sum test) between GC group and healthy controls were detected. Two potential gastric serum biomarkers (m/z values of 1546.02 and 5335.08), with higher and specific expression in GC patients were further identified as peptide regions of SERPINA1 and ENOSF1. Enzyme-linked immunosorbent assays (ELISAs) were used to analyze 210 additional serum samples obtained from 36 healthy volunteers, 36 GC patients, 30 GU patients, 36 nonsmall-cell lung cancer (NSCLC) patients, 36 clear-cell renal cell carcinoma (CCRCC) patients, and 36 pancreatic cancer patients to verify the expression of SERPINA1 and ENOSF1 in GC sera. The suitability of the present method for gastric serum proteomic analysis was demonstrated and led to the identification of two peptide regions and their corresponding proteins as potential serum biomarkers for the serum detection of GC.

The clinical significance of DC-SIGN and DC-SIGNR, which are novel markers expressed in human colon cancer

Background

Colon cancer has always been diagnosed at a late stage, which is associated with poor prognosis. The currently used serum tumor markers CEA and CA19-9 display low sensitivity and specificity and may not have diagnostic value in early stage colon cancer. Thus, there is an urgent need to identify novel serum biomarkers for use in the early detection of colon cancer.

Methods

In this study, the expression of DC-SIGN and DC-SIGNR in serum was detected by enzyme-linked immunosorbent assay (ELISA). DC-SIGN and DC-SIGNR expression was detected in cancer tissues by immunohistochemistry (IHC).

Results

The level of sDC-SIGN was lower in patients than in the healthy controls, while the level of sDC-SIGNR in patients was higher than in the healthy controls. Both sDC-SIGN and sDC-SIGNR had diagnostic significances for cancer patients, and the combined diagnosis of these two markers was higher than both of them alone. Furthermore, there were significant differences between both sDC-SIGN and sDC-SIGNR in stage I/II patients and the healthy controls. Moreover, high sDC-SIGN level was accompanied with the long survival time. Additionally, DC-SIGNR was negative in the cancer foci and matched normal colon tissues but was weakly positive between the cancer foci. DC-SIGN staining was faint in matched normal colon tissues, strong in the tumor stroma and the invasive margin of colon cancer tissues, and negatively correlated with the sDC-SIGN level in serum from the same patient. Interestingly, the percent survival of patients with a DC-SIGN mean density of>0.001219 (the upper 95% confidence interval of matched normal colon tissues) was higher than for all other patients.

Conclusion

DC-SIGN and DC-SIGNR are blood-based molecular markers that can potentially be used for the diagnosis of early stage patients. Moreover, expression of DC-SIGN in serum and cancer tissues may affect the survival time for colon cancer patients.

REG4 independently predicts better prognosis in non-mucinous colorectal cancer

Introduction

Colorectal cancer (CRC) is one of the world’s three most common cancers and its incidence is rising. To identify patients who benefit from adjuvant therapy requires novel biomarkers. The regenerating islet-derived gene (REG) 4 belongs to a group of small secretory proteins involved in cell proliferation and regeneration. Its up-regulated expression occurs in inflammatory bowel diseases also in gastrointestinal cancers. Reports on the association of REG4 expression with CRC prognosis have been mixed. Our aim was to investigate tumor REG4 expression in CRC patients and its coexpression with other intestinal markers.

Methods

Tumor expression of REG4 was evaluated by immunohistochemistry in 840 consecutive surgically treated CRC patients at Helsinki University Central Hospital. Expression of MUC1, MUC2, MUC5AC, synapthophysin, and chromogranin was evaluated in a subgroup of 220 consecutively operated CRC patients. REG4 expression with clinicopathological parameters, other intestinal markers, and the impact of REG4 expression on survival were assessed.

Results

REG4 expression associated with favorable clinicopathological parameters and with higher overall survival from non-mucinous CRC (p = 0.019). For such patients under 65, its expression was an independent marker of lower risk of death within 5 years that cancer; univariable hazard ratio (HR) = 0.57; 95% confidence interval (CI) (0.34–0.94); multivariable HR = 0.55; 95% CI (0.33–0.92). In non-mucinous CRC, REG4 associated with positive MUC2, MUC4, and MUC5AC expression.

Conclusion

We show, to our knowledge for the first time, that REG4 IHC expression to be an independent marker of favorable prognosis in non-mucinous CRC. Our results contradict those from studies based on quantification of REG4 mRNA levels, a discrepancy warranting further studies.

Serum protein and genetic tumor markers of gastric carcinoma

The high incidence of gastric cancer and consequent mortality pose severe threats to human health. Early screening, diagnosis and treatment are the key to improve the prognosis of the patients with gastric cancer. Gastroscopy with biopsy is an efficient method for the diagnosis of early gastric cancer, but the associated discomfort and high cost make it difficult to be a routine method for screening gastric cancer. Serum tumor marker assay is a simple and practical method for detection of gastric cancer, but it is limited by poor sensitivity and specificity. Therefore, people have been looking for novel serum markers of gastric cancer in recent years. Here we review the novel serum tumor markers of gastric cancer and their diagnostic significance, focusing on the discoveries from serum proteomics analyses and epigenetics researches.

REG4 contributes to the invasiveness of pancreatic cancer by upregulating MMP-7 and MMP-9

Recent studies have shown that overexpression of regenerating gene family member 4 (REG4) is associated with the initiation and progression of pancreatic cancer. In our study, we explored the role of REG4 in the invasion of pancreatic cancer. Real-time PCR and Western blot analysis were used to determine REG4 expression in pancreatic cancer cell lines. An MTT assay was carried out to test the effect of REG4 on the growth of pancreatic cancer cells. The involvement of REG4 in cancer cell invasion was examined by Transwell invasion assay. Two MMPs, MMP-7 and MMP-9, were identified from a pool of candidate genes as being related to REG4-induced cell invasion by PCR and Western blotting. Immunohistochemistry was used to confirm the correlation between REG4 and the two MMPs. High expression of REG4 was found in BXPC-3 cells and its culture media. But in PANC-1 and ASPC-1 cell lines, REG4 expression levels were very low, and no detectable protein was found in the culture medium. The MTT and Transwell invasion assays showed that recombinant REG4 protein and BXPC-3 conditioned media significantly promoted the proliferation and invasiveness of pancreatic cancer cells. It was also shown that MMP-7 and MMP-9 are upregulated by REG4 induction using real-time PCR and Western blotting analysis. Immunohistochemical study further verified this result. In conclusion, REG4 promotes not only growth but also in vitro invasiveness of pancreatic cancer cells by upregulating MMP-7 and MMP-9.

Significance of regenerating islet-derived type IV gene expression in gastroenterological cancers

The regenerating islet-derived members (Reg), a group of small secretory proteins, which are involved in cell proliferation or differentiation in digestive organs, are upregulated in several gastrointestinal cancers, functioning as trophic or antiapoptotic factors. Regenerating islet-derived type IV (RegIV), a member of the Reg gene family, has been reported to be overexpressed in gastroenterological cancers. RegIV overexpression in tumor cells has been associated with carcinogenesis, cell growth, survival and resistance to apoptosis. Cancer tissue expressing RegIV is generally associated with more malignant characteristics than that without such expression, and RegIV is considered a novel prognostic factor as well as diagnostic marker in some gastroenterological cancers. We previously investigated the expression levels of RegIV mRNA of 202 surgical colorectal cancer specimens with quantitative real-time reverse-transcriptase polymerase chain reaction and reported that a higher level of RegIV gene expression was a significant independent predictor of colorectal cancer. The biologic functions of RegIV protein in cancer tissue, associated with carcinogenesis, anti-apoptosis and invasiveness, are being elucidated by molecular investigations using transfection techniques or neutralizing antibodies of RegIV, and the feasibility of antibody therapy targeting RegIV is being assessed. These studies may lead to novel therapeutic strategies for gastroenterological cancers expressing RegIV. This review article summarizes the current information related to biological functions as well as clinical importance of RegIV gene to clarify the significance of RegIV expression in gastroenterological cancers.

Coordinated expression of REG4 and aldehyde dehydrogenase 1 regulating tumourigenic capacity of diffuse-type gastric carcinoma-initiating cells is inhibited by TGF-β

Aldehyde dehydrogenase 1 (ALDH1) has been shown to serve as a marker for cancer-initiating cells (CICs), but little is known about the regulation of the CIC functions of ALDH1+ cancer cells. We isolated ALDH1+ cells from human diffuse-type gastric carcinoma cells and characterized these cells using an Aldefluor assay. ALDH1+ cells constituted 5-8% of the human diffuse-type gastric carcinoma cells, OCUM-2MLN and HSC-39; were more tumourigenic than ALDH1- cells; and were able to self-renew and generate heterogeneous cell populations. Using gene expression microarray analyses, we identified REG4 (regenerating islet-derived family, member 4) as one of the genes up-regulated in ALDH1+ cells, and thus as a novel marker for ALDH1+ tumour cells. Induced expression of REG4 enhanced the colony-forming ability of OCUM-2MLN cells, while knockdown of REG4 inhibited the tumourigenic potential of ALDH1+ cells. We further found that TGF-β signalling reduces the expression of ALDH1 and REG4, and the size of the ALDH1+ cell population. In human diffuse-type gastric carcinoma tissues, the expression of ALDH1 and REG4 correlated with each other, as assessed by immunohistochemistry, and ALDH1 expression correlated inversely with Smad3 phosphorylation as a measure of TGF-β signalling. These findings illustrate that, in diffuse-type gastric carcinoma, REG4 is up-regulated in ALDH1+ CICs, and that the increased tumourigenic ability of ALDH1+ cells depends on REG4. Moreover, TGF-β down-regulates ALDH1 and REG4 expression, which correlates with a reduction in CIC population size and tumourigenicity. Targeting REG4 in ALDH1+ CICs may provide a novel strategy in the treatment of diffuse-type gastric carcinoma.

Advances in research and diagnosis of early gastric cancer

The overall prognosis of gastric cancer is generally poor due to late presentation and diagnosis. When detected early, the prognosis of gastric cancer is excellent, and curative endoscopic resection may be possible, without the need for surgery. Careful endoscopic examination is important so as to avoid missed lesions. Besides the endoscopic screening for gastric cancer, other screening methods are also used in different countries and areas. This also provides us different avenues for the diagnosis of early gastric cancer.