Clinical application of genetics in management of colorectal cancer

Expression of Apurinic/Apyrimidinic Endonuclease 1 in Colorectal Cancer and its Relation to Tumor Progression and Prognosis

BACKGROUND/AIM

Over-expression of apurinic/apyrimidinic endonuclease 1 (APE1) has been demonstrated to be associated with cancer progression, chemo- and radioresistance in various cancers. This study examined the expression of APE1 and its relation to tumor progression and prognosis in patients with colorectal cancer (CRC).

MATERIALS AND METHODS

We investigated 193 patients with CRC who received curative surgery for whom formalin-fixed and paraffin-embedded blocks were available, and long-term tumor-specific survival rate analysis was possible. The expression of APE1 was investigated by reverse transcription-polymerase chain reaction, western blotting, and immunohistochemistry in CRC and lymph node tissues. The apoptosis, proliferation, and angiogenesis of CRC cells were determined using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay, and immunohistochemical staining for Ki-67 and CD34 antibodies.

RESULTS

APE1 was over-expressed in CRC and metastatic lymph node tissues compared with normal colorectal mucosa and non-metastatic lymph node tissues. Over-expression of APE1 was significantly associated with advanced stage, lymphovascular invasion, perineural invasion, deeper tumor invasion, lymph node metastasis, distant metastasis, and poor survival. Multivariate analysis demonstrated that APE1, perineural invasion, and lymph node metastasis were the independent prognostic factors associated with overall survival. The mean Ki-67 labeling index value of APE1-positive tumors was significantly higher than that of APE1-negative tumors. However, there was no significant association between APE1 expression and the apoptotic index or microvessel density.

CONCLUSION

Over-expression of APE1 is significantly associated with tumor progression and poor survival in patients with CRC. Therefore, APE1 may be a novel biomarker and present a potential prognostic factor for CRC.

Survival of colorectal cancer patients in Brunei Darussalam: comparison between 2002-09 and 2010-17

Background

Colorectal cancer (CRC) is a major cause of cancer-related mortality worldwide. It is the second leading cause of cancer death in men and women in Brunei Darussalam in 2017, posing a major burden on society.

Methods

This retrospective cohort study (n = 1035 patients diagnosed with CRC in Brunei Darussalam from 1st January 2002 until 31st December 2017) aims to compare the overall survival rates of CRC patients (2002–2017), to compare survival rates between two study periods (2002–2009 and 2010–2017) and to identify prognostic factors of CRC. Kaplan-Meier estimator and log-rank tests were performed to analyse the overall survival rates of CRC patients. Multiple Cox regression was performed to determine the prognostic factors of CRC with adjusted hazard ratios (Adj. HRs) reported.

Results

The 1-, 3- and 5-year survival rates of CRC patients are 78.6, 62.5, and 56.0% respectively from 2002 to 2017. The 1-, 3-, and 5-year survival rates of CRC patients for 2002–2009 are 82.2, 69.6, and 64.7%; 77.0, 59.1, and 51.3% for 2010–2017 respectively. A significant difference in CRC patients’ survival rate was observed between the two study periods, age groups, ethnic groups, cancer stages, and sites of cancer (p < 0.05). The Adjusted Hazard Ratios (Adj. HRs) were significantly higher in the 2010–17 period (Adj. HR = 1.78, p < 0.001), older age group ( ≥ 60 years) (Adj. HR = 1.93, p = 0.005), distant cancer (Adj. HR = 4.69, p < 0.010), tumor at transverse colon and splenic flexure of colon (Adj. HR = 2.44, p = 0.009), and lower in the Chinese(Adj. HR = 0.63, p = 0.003).

Conclusion

This study highlights the lower survival rates of CRC patients in 2010–2017, Malays, older patients, distant cancer, and tumors located at the latter half of the proximal colon (transverse colon), and predominantly LCRC (splenic flexure, descending colon, sigmoid colon, overlapping lesion colon and colon (NOS), as well as the rectosigmoid junction and rectum (NOS)). Age, ethnicity, cancer stage, and tumor location are significant prognostic factors for CRC. These findings underscore the importance of public health policies and programmes to enhance awareness on CRC from screening to developing strategies for early detection and management, to reduce CRC-associated mortality.

Effect of KRAS mutational status on disease behavior and treatment outcome in patients with metastatic colorectal cancer: intratumor heterogeneity and mutational status

Background

Nowadays, the outcomes of metastatic colorectal cancer (mCRC) have considerably improved. Genetic studies evaluating KRAS mutational status are important in the personalized therapy era to understand disease heterogeneity, disease behaviors, and treatment outcomes.

Methods

This multicenter retrospective study evaluated 360 patients with mCRC treated at three oncology centers in Saudi Arabia and Egypt between February 2011 and December 2015. Patients were treated with bevacizumab and cetuximab according to guidelines. Therapy outcome, time to progression, and disease-associated death were assessed. KRAS mutational status was evaluated by testing exons 12 and 13.

Results

Approximately 220 (61.1%) cases were of wild-type KRAS, whereas KRAS mutation was noted in 38.9%. KRAS mutation was common in the descending colon, whereas a low incidence of the KRAS mutation was observed in the ascending colon (P<0.001). Among patients with KRAS mutation, 64.3% initially presented as emergency cases with obstruction/perforation (P=0.002), and 62.9% had hepatic or pulmonary metastasis. The progression-free survival (PFS) was 10.7 months. Cases without KRAS mutation showed a higher PFS than did those with KRAS mutation (mean PFS: 11.5 vs. 9.6 months, P=0.001). The overall survival was 23.2 months. The survival varied considerably according to KRAS type: patients without mutation survived for 25.0 months and those with mutation survived for 19.6 months (P<0.001). Disease-related death occurred in 132 (36.7%) cases, approximately 57.1% of them (80 cases) had KRAS mutations (P=0.001).

Conclusions

A major association between KRAS mutational status and both disease behavior and treatment outcomes was found in this study. Patients with KRAS mutation show advanced disease presentation, with lower PFS and overall survival.

Genetic and epigenetic alterations of colorectal cancer

Colorectal cancer (CRC) arise from multi-step carcinogenesis due to genetic mutations and epigenetic modifications of human genome. Genetic mutations and epigenetic modifications were originally established as 2 independent mechanisms contributing to colorectal carcinogenesis. However, recent evidences demonstrate that there are interactions between these 2 mechanisms. Genetic mutations enable disruption of epigenetic controls while epigenetic modifications can initiate genomic instability and carcinogenesis. This review summarized genetic mutations and epigenetic modifications in colorectal carcinogenesis and molecular classification of CRC subtype based on genetic or epigenetic biomarkers for treatment response and prognosis. Molecular subtypes of CRC will permit the implementation of precision medicine with better outcome of management for CRC.

Hepatitis B Virus Infection Is Independently Associated With Advanced Colorectal Adenoma

BACKGROUND

Studies on the association of chronic hepatitis B virus (HBV) infection with colonic neoplasm are rare. We aimed to investigate the association between chronic HBV infection and the development of colonic adenoma.

MATERIALS AND METHODS

One hundred thirty-three patients with chronic HBV infection who underwent colonoscopic examination, were enrolled. A healthy HBV-uninfected group was matched with the HBV group. Those with a previous history of colorectal cancer, inflammatory bowel diseases or colorectal surgery were excluded from both HBV and HBV-uninfected groups. Clinical information and data on age, sex, body mass index, smoking, alcohol consumption and comorbidities were obtained. Advanced adenoma was defined as tubular adenoma ≥10mm, or adenoma with a villous component or high-grade dysplasia.

RESULTS

The HBV group had a higher rate of colorectal adenoma and advanced adenoma than the HBV-uninfected group. Patients in the HBV group had larger colorectal polyps than those in the HBV-uninfected group. In the chi square test, HBV DNA positivity was significantly associated with colorectal adenoma (P < 0.001) and advanced adenoma (P = 0.007). HBV infection (odds ratio [OR] = 23.961, 95% CI: 9.400-61.076), diabetes mellitus (OR = 2.633, 95% CI: 1.071-6.473) and age (OR = 1.057, 95% CI: 1.020-1.095) were significantly associated with advanced adenoma in the multivariable logistic regression analysis. Multivariable logistic regression analysis within the HBV group revealed that HBV DNA (OR = 1.236, 95% CI: 1.029-1.485) was associated with advanced adenoma.

CONCLUSIONS

HBV DNA in patients with HBV infection and HBV infection are independently associated with advanced colorectal adenoma development.

Filamin A interacting protein 1-like expression inhibits progression in colorectal cancer

Filamin A interacting protein 1-like (FILIP1L) expression, which is decreased in various cancers, may inhibit carcinogenesis. In this study, we evaluated the effects of FILIP1L on oncogenic behavior and prognosis in colorectal cancer. siRNA-mediated FILIP1L knockdown enhanced tumor cell migration and invasion and inhibited apoptosis and cell cycle arrest in COLO205 cells. pcDNA-myc vector-mediated FILIP1L overexpression suppressed tumor cell migration and invasion and induced apoptosis and cell cycle arrest in HCT116 cells. FILIP1L knockdown enhanced angiogenesis by increasing VEGF-A and HIF-1α levels and decreasing angiostatin level. FILIP1L overexpression suppressed angiogenesis by decreasing VEGF-A and -D l level and increasing angiostatin and endostatin levels. Phosphorylated β-catenin levels decreased and phosphorylated Akt and GSK-3β levels increased following FILIP1L knockdown. FILIP1L overexpression had the opposite effects. FILIP1L expression was associated with reductions in tumor size, cell differentiation, lymphovascular invasion, stage, invasion depth and lymph node metastasis, and with longer overall survival. Mean Ki-67 labeling indexes and microvessel density values were lower in FILIP1L-positive tumors than in FILIP1L-negative tumors. These results indicate that FILIP1L suppresses tumor progression by inhibiting cell proliferation and angiogenesis in colorectal cancer.

Characterisation of the oxysterol metabolising enzyme pathway in mismatch repair proficient and deficient colorectal cancer

Oxysterols are oxidised derivatives of cholesterol, formed by the enzymatic activity of several cytochrome P450 enzymes and tumour-derived oxysterols have been implicated in tumour growth and survival. The aim of this study was to profile the expression of oxysterol metabolising enzymes in primary colorectal cancer and assess the association between expression and prognosis.

Immunohistochemistry was performed on a colorectal cancer tissue microarray containing 650 primary colorectal cancers using monoclonal antibodies to CYP2R1, CYP7B1, CYP8B1, CYP27A1, CYP39A1, CYP46A1 and CYP51A1, which we have developed. Unsupervised hierarchical cluster analysis was used to examine the overall relationship of oxysterol metabolising enzyme expression with outcome and based on this identify an oxysterol metabolising enzyme signature associated with prognosis.

Cluster analysis of the whole patient cohort identified a good prognosis group (mean survival=146 months 95% CI 127-165 months) that had a significantly better survival (δ²=12.984, p<0.001, HR=1.983, 95% CI 1.341-2.799) than the poor prognosis group (mean survival=107 months, 95% CI 98-123 months). For the mismatch repair proficient cohort, the good prognosis group had a significantly better survival (δ²=8.985, p=0.003, HR=1.845, 95% CI 1.227-2.774) than the poor prognosis group. Multi-variate analysis showed that cluster group was independently prognostically significant in both the whole patient cohort (p=0.02, HR=1.554, 95% CI 1.072-2.252) and the mismatch repair proficient group (p=0.04, HR=1.530, 95% CI 1.014-2.310).

Individual oxysterol metabolising enzymes are overexpressed in colorectal cancer and an oxysterol metabolising enzyme expression profile associated with prognosis has been identified in the whole patient cohort and in mismatch repair proficient colorectal cancers.

Three-year colonoscopy surveillance after polypectomy in Korea: a Korean Association for the Study of Intestinal Diseases (KASID) multicenter prospective study

Background/Aims

Colonoscopic surveillance is currently recommended after polypectomy owing to the risk of newly developed colonic neoplasia. However, few studies have investigated colonoscopy surveillance in Asia. This multicenter and prospective study was undertaken to assess the incidence of advanced adenoma based on baseline adenoma findings at 3 years after colonoscopic polypectomy.

Methods

A total of 1,323 patients undergoing colonoscopic polypectomy were prospectively assigned to 3-year colonoscopy surveillance at 11 tertiary endoscopic centers. Relative risks for advanced adenoma after 3 years were calculated according to baseline adenoma characteristics.

Results

Among 1,323 patients enrolled, 387 patients (29.3%) were followed up, and the mean follow-up interval was 31.0±9.8 months. The percentage of patients with advanced adenoma on baseline colonoscopy was higher in the surveillance group compared to the non-surveillance group (34.4% vs. 25.7%). Advanced adenoma recurrence was observed in 17 patients (4.4%) at follow-up. The risk of advanced adenoma recurrence was 2 times greater in patients with baseline advanced adenoma than in those with baseline non-advanced adenoma, though the difference was not statistically significant (6.8% [9/133] vs. 3.1% [8/254], P=0.09). Advanced adenoma recurrence was observed only in males and in subjects aged ≥50 years. In contrast, adenoma recurrence was observed in 187 patients (48.3%) at follow-up. Male sex, older age (≥50 years), and multiple adenomas (≥3) at baseline were independent risk factors for adenoma recurrence.

Conclusions

A colonoscopy surveillance interval of 3 years in patients with baseline advanced adenoma can be considered appropriate.

Obesity-related parameters and colorectal adenoma development

BACKGROUND

Obesity increases the risk of colorectal adenoma and colorectal cancer. However, the obesity-related parameters that are best for assessing the risk of colorectal adenoma development remain unclear. We analyzed the parameters that may best describe the association between obesity and colorectal adenoma development.

METHODS

In this retrospective cohort study, 3405 individuals underwent screening colonoscopy during routine health examinations. We measured body mass index; waist circumference; and metabolic parameters such as high-density lipoprotein-cholesterol, glucose, triglyceride, and systolic blood pressure. We analyzed the risk of developing colorectal adenoma, relative to obesity-related parameters, over a mean interval of 5.8 years from baseline colonoscopy.

RESULTS

In a multivariate analysis, waist circumference was the only obesity-related marker associated with an increased risk of metachronous colorectal adenoma. Men with waist circumferences ≥85 cm and women with waist circumference ≥82 cm had a 31% increased risk of metachronous colorectal adenoma compared to those with smaller waist circumferences [odds ratio (OR) 1.31; 95% confidence interval (CI, 1.09-1.57)]. Other factors associated with metachronous colorectal adenoma were age (OR, 1.03; 95% CI 1.02-1.04), male sex (OR 1.49; 95% CI 1.17-1.88), alcohol consumption ≥3/week (OR 1.33; 95% CI 1.10-1.62), the number of adenoma at baseline (OR 1.21; 95% CI 1.10-1.33), and the presence of advanced adenoma at baseline (OR 1.60; 95% CI 1.24-2.06).

CONCLUSIONS

Our findings suggest that central obesity, represented by waist circumference, is a significant predictor of metachronous colorectal adenoma, independent of body mass index and other metabolic variables.

Is methylation analysis of SFRP2, TFPI2, NDRG4, and BMP3 promoters suitable for colorectal cancer screening in the Korean population?

Background/Aims

Colorectal cancer (CRC) screening using stool DNA was recently found to yield good detection rates. A multi-target stool DNA test (Cologuard®, Exact Sciences), including methylated genes has been recently approved by the U.S. Food and Drug Administration. The aim of this study was to validate these aberrantly methylated genes as stool-based DNA markers for detecting CRC and colorectal advanced adenoma (AA) in the Korean population.

Methods

A single-center study was conducted in 36 patients with AA; 35 patients with CRC; and 40 endoscopically diagnosed healthy controls using CRC screening colonoscopy. The methylation status of the SFRP2, TFPI2, NDRG4, and BMP3 promoters was investigated blindly using bisulfate-modified stool DNA obtained from 111 participants. Methylation status was investigated by methylation-specific polymerase chain reaction.

Results

Methylated SFRP2, TFPI2, NDRG4, and BMP3 promoters were detected in 60.0%, 31.4%, 68.8%, and 40.0% of CRC samples and in 27.8%, 27.8%, 27.8%, and 33.3% of AA samples, respectively. The sensitivities obtained using 4 markers to detect CRC and AA were 94.3% and 72.2%, respectively. The specificity was 55.0%.

Conclusions

Our results demonstrate that the SFRP2, TFPI2, NDRG4, and BMP3 promoter methylation analysis of stool sample DNA showed high sensitivity but low specificity for detecting CRC and AA. Because of the low specificity, 4 methylated markers might not be sufficient for CRC screening in the Korean population. Further large-scale studies are required to validate the methylation of these markers in the Asian population and to find new markers for the Asian population.

Field Cancerization in Sporadic Colon Cancer

BACKGROUND/AIMS

Aberrant DNA methylation has a specific role in field cancerization. Certain molecular markers, including secreted frizzled-related protein 2 (SFRP2), tissue factor pathway inhibitor 2 (TFPI2 ), N-Myc downstream-regulated gene 4 (NDRG4) and bone morphogenic protein 3 (BMP3), have previously been shown to be hypermethylated in colorectal cancer (CRC). We aim to examine field cancerization in CRC based on the presence of aberrant DNA methylation in normal-appearing tissue from CRC patients.

METHODS

We investigated promoter methylation in 34 CRC patients and five individuals with normal colonoscopy results. CRC patients were divided into three tissue groups: tumor tissue, adjacent and nonadjacent normal-appearing tissue. The methylation status (positive: methylation level >20%) of SFRP2 , TFPI2 , NDRG4 , and BMP3 promoters was investigated using methylation-specific PCR.

RESULTS

The methylation frequencies of the SFRP2 , TFPI2 , NDRG4 and BMP3 promoters in tumor/adjacent/nonadjacent normal-appearing tissue were 79.4%/63.0%/70.4%, 82.4%/53.6%/60.7%, 76.5%/61.5%/69.2%, 41.2%/35.7%/50.0%, respectively. The methylation levels of the SFRP, TFPI2, NDRG4 and BMP3 promoters in tumor tissues were significantly higher than those in normal-appearing tissue (SFRP2, p=0.013; TFPI2, p<0.001; NDRG4, p=0.003; BMP3, p=0.001). No significant correlation was observed between the methylation levels of the promoters and the clinicopathological variables.

CONCLUSIONS

The field effect is present in CRC and affects both the adjacent and nonadjacent normal-appearing mucosa.

Malformin A1 treatment alters invasive and oncogenic phenotypes of human colorectal cancer cells through stimulation of the p38 signaling pathway

Malformin A1 (MA1), a cyclic pentapeptide isolated from Aspergillus niger, has been found to possess a range of bioactive properties including antibacterial activity. However, it is unclear whether MA1 exerts an anticancer effect or not. In this study, we conducted in vitro experiments to investigate its anticancer properties in human colorectal cancer cells. The effect of MA1 on human colorectal cancer cells, SW480 and DKO1, was examined by the WST-1 cell viability assay, inverted microscopy, 5-bromo-2-deoxyuridine (BrdU) incorporation, flow cytometry, DNA fragmentation, wound healing, Transwell assays, and western blotting. MA1 treatment showed potent cytotoxic activities on human colorectal cancer cells. MA1 treatment induced apoptosis by activating the poly(ADP-ribose) polymerase (PARP), caspase‑3, -7, and -9. MA1 treatment led to the increase in p53 upregulated modulator of apoptosis (PUMA) and the decrease in X-linked inhibitor of apoptosis protein (XIAP) and Survivin. In addition, MA1 treatment induced cell cycle arrest in the sub-G1 phase. The pan-caspase inhibitor, Z‑VAD‑FMK, attenuated these MA1-induced apoptotic effects on human colorectal cancer cells. Moreover, MA1 treatment suppressed tumor cell migration and invasion. The phosphorylation level of p38 was upregulated by MA1 treatment, and the inhibitor of p38, SB203580, attenuated the MA1-induced p38 phosphorylation as well as caspase‑3 and PARP activation. These results indicate that MA1 treatment alters invasive and oncogenic phenotypes of human colorectal cancer cells through the stimulation of the p38 signaling pathway.

The differential expression of omega-3 and omega-6 fatty acid metabolising enzymes in colorectal cancer and its prognostic significance

Background:

Colorectal cancer is a common malignancy and one of the leading causes of cancer-related deaths. The metabolism of omega fatty acids has been implicated in tumour growth and metastasis.

Methods:

This study has characterised the expression of omega fatty acid metabolising enzymes CYP4A11, CYP4F11, CYP4V2 and CYP4Z1 using monoclonal antibodies we have developed. Immunohistochemistry was performed on a tissue microarray containing 650 primary colorectal cancers, 285 lymph node metastasis and 50 normal colonic mucosa.

Results:

The differential expression of CYP4A11 and CYP4F11 showed a strong association with survival in both the whole patient cohort (hazard ratio (HR)=1.203, 95% CI=1.092–1.324, χ²=14.968, P=0.001) and in mismatch repair-proficient tumours (HR=1.276, 95% CI=1.095–1.488, χ²=9.988, P=0.007). Multivariate analysis revealed that the differential expression of CYP4A11 and CYP4F11 was independently prognostic in both the whole patient cohort (P=0.019) and in mismatch repair proficient tumours (P=0.046).

Conclusions:

A significant and independent association has been identified between overall survival and the differential expression of CYP4A11 and CYP4F11 in the whole patient cohort and in mismatch repair-proficient tumours.

Expression of inositol-requiring enzyme 1β is downregulated in colorectal cancer

The endoplasmic reticulum stress inositol-requiring enzyme (IRE) 1α/X-box binding protein (XBP) 1 signaling pathway is involved in the tumorigenesis of breast and prostate cancer. Mucin 2 (MUC2) protects colon tissues from the formation of tumors. In human colorectal cancer (CRC) the role of IRE1α, and its analogue, IRE1β, has yet to be elucidated. In the present study, the expression levels of IRE1α, IRE1β, un-spliced XBP1u, spliced XBP1s and MUC2 in surgically resected cancerous and adjacent non-cancerous tissues from patients with CRC were investigated. The IRE1α, IRE1β, XBP1u, XBP1s and MUC2 mRNA expression levels were determined using reverse transcription-quantitative polymerase chain reaction, and the protein expression levels were detected using immunohistochemistry and western blotting. The association between the expression levels of IRE1α, IRE1β and MUC2 and the clinicopathological features of patients with CRC was subsequently analyzed. The mRNA expression levels of IRE1β and MUC2 were decreased by ~2.1 and ~4.5-fold in CRC tissues, respectively, as compared with the adjacent normal tissues. The protein expression levels of IRE1β and MUC2 were decreased by ~8.0 and ~2.0-fold in the CRC tissues, respectively. IRE1β mRNA expression levels were positively correlated with MUC2 mRNA expression levels. IRE1β expression levels were revealed to be significantly associated with lymph node metastasis, tumor stage and histological differentiation. However, IRE1α, XBP1u and XBP1s mRNA and IRE1α protein expression levels were not observed to significantly differ between cancerous tissues and the adjacent normal tissues. The results indicated that the expression of IRE1β, but not IRE1α, may protect colon tissue from developing CRC by inducing MUC2 expression. Therefore, decreased IRE1β expression levels may be associated with the development of CRC through the inhibition of MUC2 expression.

Statin use and the risk of colorectal adenoma: A meta-analysis

BACKGROUND

Although statin use has been reported to reduce the risk of colorectal cancer beyond its cholesterol-lowering effects, the benefit of statins against colorectal adenoma has not been fully clarified. We aimed to investigate the association between statin use and the risk of colorectal adenoma.

METHODS

We conducted a systematic literature search on MEDLINE, EMBASE, and the Cochrane Library using the primary keywords "adenoma," "polyp," "colorectal," "colon," "rectal," "rectum," "neoplasia," "neoplasm," "statin," "3-hydroxy-3-methylglutaryl-coenzyme A," and "HMG-CoA." Studies were included if they evaluated the association between statin use and adenoma and reported relative risks (RRs) or odds ratios or provided data for estimation. Pooled estimates were calculated using the random-effects model.

RESULTS

Six studies including 13 239 patients were analyzed. The median proportion of patients with any adenoma was 29.7% (range, 20.9-38.4%) in patients taking statins and 31.2% (range, 19.6-63.4%) in patients not taking statins across included studies. The median proportion of patients with advanced adenoma in those taking statins was 7.7% (range, 3.1-27.2%), whereas that in patients not taking statins was 11.3% (range, 3.5-32.4%). On meta-analysis, statin use did not significantly affect the risk of any adenoma (pooled RR = 0.901; 95% confidence interval [CI], 0.735-1.104); however, it was associated with a lower risk of advanced adenoma (pooled RR = 0.833; 95% CI, 0.750-0.925).

CONCLUSIONS

Statin use seems to be associated with a reduced risk of advanced adenoma, but not any adenoma. Statins may prevent neoplastic progression of adenomas rather than the development of adenomas.

Does Low Threshold Value Use Improve Proximal Neoplasia Detection by Fecal Immunochemical Test?

BACKGROUND

Several studies have reported that the fecal immunochemical test (FIT) less sensitively detects proximal advanced neoplasia (AN) compared to distal AN. Low threshold value use may improve proximal AN detection.

AIM

To investigate whether FIT diagnostic accuracy for AN is different according to AN location and to compare FIT accuracy in proximal AN detection using different threshold values.

METHODS

This retrospective study was conducted in a university hospital in Korea from June 2013 to May 2015. Out of 34,547 participants who underwent FITs, 3990 subjects aged ≥50 years who also underwent colonoscopies were analyzed. The FIT diagnostic accuracy for AN with differing locations (proximal vs. distal) and threshold values (20, 15, and 10 mcg Hb/g feces) were assessed.

RESULTS

The sensitivity, specificity, positive predictive value, and negative predictive value of FIT in AN detection were 42.2, 84.3, 24.1, and 92.5 %, respectively. The FIT sensitivity for proximal AN detection was significantly lower than that for distal AN detection (32.7 and 49.0 %, respectively; P = 0.001). Lowering FIT threshold values tended to increase the sensitivity for proximal AN, whereas it significantly decreased the specificity for proximal AN. As a result, there was no significant difference in the accuracy for proximal AN detection (80.1, 79.3, and 78.1 % for 20, 15, and 10 mcg Hb/g feces, respectively; P = 0.107).

CONCLUSIONS

FIT was less sensitive in proximal AN detection than distal AN detection. Lowering the FIT cutoff threshold did not increase the accuracy for proximal AN detection. New biomarker development for colorectal cancer screening is required to improve proximal ACRN diagnostic accuracy.

Myofibroblasts of the muscle layer stimulate the malignant potential of colorectal cancer

Myofibroblasts of colorectal cancer (CRC) have been associated with histopathological factors such as lymph node metastasis, liver metastasis and local recurrence. However, few studies have assessed the association between these malignant potentials and the myofibroblast distribution in CRC. We aimed to evaluate the relationship between clinical factors and myofibroblast distribution around CRC invasive lesions. The study included 121 cases of pT3 CRC that were diagnosed at stage II or III. Myofibroblast density of the following three histological layers was measured: the submucosa (SM), muscularis propria (MP) and subserosa (SS). We analyzed the relationship between the clinicopathological factors and myofibroblast density by studying the histopathological features of the three layers. The myofibroblast density of the MP layer was significantly higher in the groups with high-frequency lymphatic and venous invasion than the groups with low-frequency lymphatic (P<0.001) and venous (P<0.01) invasion, respectively. In the positive lymph node metastasis group, the myofibroblast density at the MP layer was significantly higher than that in the negative lymph node metastasis group (P<0.001). The high myofibroblast density group at the MP layer was significantly associated with poor overall survival (P<0.003). Our study indicated that myofibroblasts are a type of cancer-associated fibroblasts and that the myofibroblast distribution contributes to the malignant potential of CRC. Furthermore, we demonstrated that myofibroblasts present at the MP layer play an important role in the malignant potential and poor prognosis of patients with CRC.

Does Stenting as a Bridge to Surgery in Left-Sided Colorectal Cancer Obstruction Really Worsen Oncological Outcomes?

BACKGROUND

Although self-expandable metal stents are used as a bridge to surgery in patients with colorectal cancer obstruction, their long-term oncological outcomes are unclear.

OBJECTIVE

The aim of this study was to investigate long-term oncological outcomes of self-expandable metal stents as a bridge to surgery (stent group) compared with direct surgery (direct operation group) in patients with left-sided colorectal cancer obstruction.

DESIGN

This was a retrospective chart review.

SETTINGS

This study was conducted at a single tertiary academic center.

PATIENTS

Of 113 patients who underwent curative surgery for left-sided colorectal cancer obstruction at Asan Medical Center between 2005 and 2011, 42 underwent direct surgery and 71 underwent self-expandable metal stent insertion followed by elective surgery. After 1:1 propensity-score matching, 42 patients were enrolled in both groups, and their postsurgical outcomes were compared.

MAIN OUTCOME MEASURES

The primary outcomes of this study were long-term oncological outcomes, including overall survival and recurrence-free survival of patients in both groups.

RESULTS

Three- and 5-year overall survival rates were similar in the stent (87.0% and 71.0%) and direct operation (76.4% and 76.4%) groups (p = 0.931). Three- and 5-year recurrence-free survival rates were also similar in the stent (91.9% and 66.4%) and direct operation (81.2% and 71.2%) groups (p = 0.581), as were postsurgical complication rates (9.5% and 16.7%; p = 0.344). No patient in either group experienced a permanent stoma.

LIMITATIONS

This study was limited by its small patient numbers and retrospective nature.

CONCLUSIONS

The long-term oncological outcomes of self-expandable metal stents as a bridge to surgery may not be inferior to those of direct surgery for left-sided colorectal cancer obstruction.

Fecal hemoglobin concentration is useful for risk stratification of advanced colorectal neoplasia

BACKGROUND

Although a fecal immunochemical test (FIT) allows quantitation of fecal hemoglobin (f-Hb), it is typically used as a binary result to identify subjects above a predetermined cut-off concentration.

AIMS

To investigate whether f-Hb concentration is useful for risk stratification of advanced colorectal neoplasia (CRN).

METHODS

This was a retrospective study conducted in a university hospital in Korea. Of 34,547 participants who underwent FIT from June 2013 to May 2015, 1532 (4.4%) showed positive results (≥100ng Hb/ml). Of participants with positive results, 738 subjects aged ≥50 years who underwent colonoscopy were analyzed.

RESULTS

Increasing quartile of f-Hb concentration (Q4 vs. Q1; odds ratio, 3.87; 95% confidence interval, 2.36-6.34), as well as older age, male sex, smoking, and metabolic syndrome (MetS), was significantly associated with a higher prevalence of advanced CRN. Risk for advanced CRN increased 5.13-, 4.27-, 5.12-, and 7.15-fold, respectively, among individuals with f-Hb in the fourth quartile who had risk factors such as age ≥70 years, male sex, smoking, and MetS compared with individuals with first quartile levels of f-Hb who did not have those risk factors.

CONCLUSION

In addition to age, sex, smoking status, and MetS, f-Hb concentration in individuals with positive results from FIT can be used to stratify the probability of detection of advanced CRN.

Risk of Advanced Colorectal Neoplasia According to the Number of High-Risk Findings at Index Colonoscopy: A Korean Association for the Study of Intestinal Disease (KASID) Study

BACKGROUND

Data regarding outcomes for patients with multiple findings for high-risk adenomas are scarce.

AIM

To compare the risk for colorectal neoplasm (CRN) recurrence according to the number of high-risk findings.

METHODS

This was a retrospective and multicenter study. Patients who had one or more high-risk adenomas at the index colonoscopy and underwent follow-up colonoscopy 2.5 or more years after the index colonoscopy were included. The number of high-risk findings was defined as follows: number of adenomas larger than 1 cm + number of adenomas with HGD + number of adenomas with a villous component + existence (counted as 1) or nonexistence (counted as 0) of three or more adenomas.

RESULTS

A total of 1646 patients were included, and the mean duration between index and follow-up colonoscopy was approximately 4 years. The cumulative incidence rate of recurrent advanced CRN in patients with three or more high-risk findings was higher than that in patients with one or two high-risk findings (p < 0.001). However, the difference in 3-year cumulative incidence rates of recurrent advanced CRN between the two groups was not great, although it was statistically significant (4.8 vs. 2.3 %, p = 0.039).

CONCLUSIONS

A 3-year surveillance interval for patients with multiple high-risk findings, regardless of the number of high-risk findings, appears reasonable.

Long-Term Outcome and Prognostic Factors of Sporadic Colorectal Cancer in Young Patients: A Large Institutional-Based Retrospective Study

The prognosis of early-onset sporadic colorectal cancer (CRC) patients remains controversial. The objective of this study was to assess the long-term outcome and prognostic factors of sporadic CRC in young patients.From 2006 to 2011, 8207 patients underwent curative or palliative surgery for CRCs in our institution. A total of 693 patients who were ≤45 years old with sporadic CRC were enrolled as the young group. A total of 1823 patients aged between 56 and 65 years were identified as middle-aged control group for this study. Survival outcome and prognostic factors were compared between the two groups.Young patients had higher recurrence rate than older patients in stages I and II (8.8% vs 2.7%, P <0.001). There was no significant difference of recurrence rate in stage III and IV cancers (27.5% vs 27.9%, P = 0.325). Metachronous cancers were developed more frequently in young patients (1.4% vs 0.6%, P = 0.038). Advanced stage CRC was diagnosed significantly more common in the young group (55.6% vs 47.9%, P = 0.001). High microsatellite instability (MSI) tumors are less likely to have advanced stage cancers (odds ratio (OR) 0.23, 95% confidence interval (CI) = 0.07-0.70) or cancer recurrence (OR 0.11, 95% CI = 0.01-0.85) in young patients. Cancer-specific survival was worse in young patients than that in older patients (81.2% vs 87.8%, P <0.001). However, there was no significant difference in cancer-specific survival for each stage between the two groups. Independent prognostic factors for survival in young patients were undifferentiated cancer (hazard ratio (HR) 2.30, 95% CI = 1.23-4.31) and 3 months or longer duration of symptom (HR 2.57, 95% CI = 1.34-4.94). Young women had better survival compared with young men (HR 0.55, 95% CI = 0.33-0.90).Prognosis of sporadic CRC in young patients is poorer than older patients, because of poorer histologic differentiation and delay in diagnosis. Early detection of CRC confers survival benefit to young patients. Because of higher recurrence rate and metachronous cancer risk, post-operative surveillance is also important in young patients.

Associations between amount of smoking and alcohol intake and risk of colorectal neoplasm

BACKGROUND AND AIM

Although smoking and alcohol has been linked to an increased risk of colorectal neoplasm (CRN), large-scale studies to identify dose-dependent relationship between amount of smoking and alcohol consumption and risk of CRN are rare. We aimed to investigate the risk for CRN according to the amount of smoking and alcohol intake in a large sample of Korean adults.

METHODS

A cross-sectional study was performed on 31,714 examinees aged ≥30 years undergoing their first colonoscopy as part of routine preventive health care between 2010 and 2011. Never smokers were compared with six groups of smokers according to smoking amount, and individuals with alcohol intake of ≤ 6.25 g ethanol per day were compared with three groups according to alcohol amount.

RESULTS

In adjusted models, the risk of overall CRN increased with increasing amount of smoking (P for trend < 0.001). The adjusted odds ratios for overall CRN comparing never smokers with six smoker groups according to smoking amount (≤2.50, 2.51-5.60, 5.61-9.00, 9.01-13.00, 13.01-19.50, and ≥19.51 pack-years) were 1.02, 1.19, 1.35, 1.53, 1.63, and 2.03, respectively. In addition, the risk of both non-advanced and advanced CRN increased with increasing amount of smoking (both P for trend < 0.001). However, the amount of alcohol consumption was not correlated with the risk of CRN.

CONCLUSIONS

The prevalence of CRN was associated with increasing amount of smoking in a dose-response manner, whereas it was not associated with the amount of alcohol consumption. Our study suggests that smoking amount as well as smoking status should be considered for CRN risk stratification.

Risk Factors Such as Male Sex, Smoking, Metabolic Syndrome, Obesity, and Fatty Liver Do Not Justify Screening Colonoscopies Before Age 45

BACKGROUND

Recently, many studies have reported that male sex, smoking, fatty liver, metabolic syndrome (MetS), and obesity are risk factors for colorectal neoplasia (CRN). However, current guidelines recommend that persons at average risk of colorectal cancer begin screening colonoscopy at age 50 years without consideration of those risk factors.

AIM

To investigate an appropriate time to start screening colonoscopies in persons with risk factors for CRN.

METHODS

We performed a cross-sectional study on 27,894 Korean aged ≥30 years who underwent a first colonoscopy as part of a health screening program. To compare the efficacy of colonoscopic screening for the detection of advanced CRN among age groups with risk factors, we calculated the number needed to screen (NNS) to identify 1 patient with advanced CRN.

RESULTS

The NNS for those 30-39 years old with all risk factors, male gender, smoking (≥10 pack-years), MetS, obesity, and fatty liver, was higher than that for ≥50-year-old female subjects (55.4 vs. 26.4). The NNS for those 40-44 years old with all risk factors (37.1) was also higher than that for ≥50-year-old female subjects. However, the NNS for those 45-49 years old with risk factors (16.9-22.9) was lower than that for ≥50-year-old women.

CONCLUSIONS

The efficacy of colonoscopic screening in people 30-44 years old with multiple risk factors is lower than that in ≥50-year-old women. Risk factors such as male sex, smoking, MetS, obesity, and fatty liver do not justify starting screening colonoscopies before age 45.

Effect of Recepteur d'Origine Nantais expression on chemosensitivity and tumor cell behavior in colorectal cancer

Recepteur d'Origine Nantais (RON) expression is known to induce oncogenic properties including tumor cell growth, survival, motility, angiogenesis and chemoresistance. In the present study, we evaluated whether RON affects chemosensitivity and oncogenic behavior of colorectal cancer cells and investigated its prognostic value in colorectal cancer. To evaluate the impact of RON on chemosensitivity and tumor cell behavior, we treated colorectal cancer cells with small interfering RNAs specific to RON. This was followed by flow cytometric analyses and migration, Matrigel invasion and endothelial tube formation assays. The expression of RON was investigated by immunohistochemistry in colorectal cancer tissues. TUNEL assay and immunohistochemical staining for CD34 and D2-40 were deployed to determine apoptosis, angiogenesis and lymphangiogenesis. RON knockdown enhanced 5-fluorouracil (FU)-induced apoptosis by upregulating the activities of caspases and expression of proapoptotic genes. Moreover, it enhanced 5-FU-induced cell cycle arrest by decreasing the expression of cyclins and cyclin‑dependent kinases and inducing that of p21. Furthermore, RON knockdown augmented the 5-FU-induced inhibition of invasion and migration of colorectal cancer cells. The β-catenin signaling cascade was blocked by RON knockdown upon 5-FU treatment. RON knockdown also decreased endothelial tube formation and expression of VEGF-A and HIF-1α and increased angiostatin expression. Furthermore, it inhibited lymphatic endothelial cell tube formation and the expression of VEGF-C and COX-2. RON expression was observed to be associated with age, tumor size, lymphovascular and perineural invasion, tumor stage, lymph node and distant metastasis, and poor survival rate. The mean microvessel density value of RON-positive tumors was significantly higher than that of RON-negative ones. These results indicate that RON is associated with tumor progression by inhibiting chemosensitivity and enhancing angiogenesis in colorectal cancer.

Risk of Colorectal Neoplasia According to Fatty Liver Severity and Presence of Gall Bladder Polyps

BACKGROUND

Fatty liver is the hepatic manifestation of metabolic syndrome (MetS) and is a known risk factor for colorectal neoplasia (CRN). Gallbladder (GB) polyps share many common risk factors with CRN. However, studies evaluating CRN risk according to fatty liver severity and the presence of GB polyps are rare.

AIM

To investigate CRN risk according to the fatty liver severity and the presence of GB polyps.

METHODS

A retrospective cross-sectional study was performed on 44,220 participants undergoing colonoscopy and abdominal ultrasonography (US) as part of a health-screening program.

RESULTS

Of the participants, fatty liver was diagnosed as mild in 27.7 %, moderate in 5.1 %, and severe in 0.4 % and 13.4 % were diagnosed with GB polyps. Mean age of participants was 42.7 years. In adjusted models, risk of overall CRN and non-advanced CRN increased with worsening fatty liver severity (P for trend = 0.007 and 0.020, respectively). Adjusted odd ratios for overall CRN and non-advanced CRN comparing participants with mild, moderate, and severe fatty liver to participants without fatty liver were 1.13 and 1.12 for mild, 1.12 and 1.10 for moderate, and 1.56 and 1.65 for severe. The presence of GB polyps did not correlate with CRN risk after adjusting for confounders.

CONCLUSIONS

CRN risk increased with worsening fatty liver severity. However the association between GB polyp and CRN was not significant in the presence of other variables. Considering that many people undergo noninvasive abdominal US as a health screen, our study will contribute to colonoscopy screening strategies in people undergoing abdominal US.

Impact of KITENIN on tumor angiogenesis and lymphangiogenesis in colorectal cancer

Angiogenesis and lymphangiogenesis are involved in the dissemination of tumor cells from solid tumors to regional lymph nodes and various distant sites. KAI1 COOH-terminal interacting tetraspanin (KITENIN) contributes to tumor progression and poor clinical outcomes in various cancers including colorectal cancer. The aim of the present study was to evaluate whether KITENIN affects tumor angiogenesis and lymphangiogenesis in colorectal cancer. A KITENIN small interfering RNA vector was used to silence KITENIN expression in colorectal cancer cell lines including DLD1 and SW480 cells. To evaluate the ability of KITENIN to induce angiogenesis and lymphangiogenesis in human umbilical vein endothelial cells (HUVECs) and lymphatic endothelial cells (HLECs), we performed Matrigel invasion and tube formation assays. Immunohistochemistry was used to determine the expression of KITENIN in colorectal cancer tissues. Angiogenesis and lymphangiogenesis were evaluated by immunostaining with CD34 and D2-40 antibodies. KITENIN silencing inhibited both HUVEC invasion and tube formation in the DLD1 and SW480 cells. KITENIN silencing led to decreased expression of the angiogenic inducers vascular endothelial growth factor (VEGF)-A and hypoxia-inducible factor-1α and increased expression of the angiogenic inhibitor angiostatin. KITENIN silencing did not inhibit either HLEC invasion or tube formation in all tested cells, but it resulted in decreased expression of the lymphangiogenic inducer VEGF-C. KITENIN expression was significantly associated with tumor stage, depth of invasion, lymph node and distant metastases and poor survival. The mean microvessel density was significantly higher in the KITENIN-positive tumors than that in the KITENIN-negative tumors. However, the mean lymphatic vessel density of KITENIN-positive tumors was not significantly higher than that of the KITENIN-negative tumors. These results suggest that KITENIN promotes tumor progression by enhancing angiogenesis in colorectal cancer.

Clinical Features and Prognosis of Resectable Primary Colorectal Signet-Ring Cell Carcinoma

BACKGROUND/AIMS

We attempted to investigate the prognosis of signet-ring cell carcinoma (SRC) patients who underwent curative surgery by comparing them with age-, sex-, and stage-matched non-mucinous adenocarcinoma (NMAC) patients.

METHODS

Between January 2003 and December 2011, 19 patients with primary SRC of the colorectum underwent curative surgery. Four SRC patients under the age of 40 were excluded, and the clinicopathological data of 15 patients (7 men; median age, 56 years) were reviewed and compared with the data of 75 NMAC patients matched by age, sex, and pathologic stage.

RESULTS

The median follow-up duration was 30.1 months for the SRC group and 43.7 months for the NMAC group (P=0.141). Involvement of the left side of the colon (73.3% vs. 26.7%, P=0.003) and infiltrative lesions such as Borrmann types 3 and 4 (85.7% vs. 24.0%, P=0.001) were more common in the SRC group than in the NMAC group. The five-year overall survival rate was significantly lower for patients with SRC than for those with NMAC (46.0% vs. 88.7%, hazard ratio, 6.99; 95% confidence interval, 2.33-20.95, P=0.001).

CONCLUSIONS

Patients with even resectable primary colorectal SRC had a poorer prognosis than age-, sex-, and stage-matched colorectal NMAC patients.

Impact of prospero homeobox-1 on tumor cell behavior and prognosis in colorectal cancer

Prospero homeobox 1 (PROX1) is up-regulated in colorectal cancer and plays an oncogenic role. In the present study, we sought to investigate the impact of PROX1 on oncogenic processes and to assess the prognostic value of PROX1 expression in colorectal cancer. A small interfering RNA or pcDNA6-myc vector was used to control PROX1 gene expression in colorectal cancer DLD1 and SW480 cell lines. The expression of PROX1 in colorectal cancer tissues was investigated by immunohistochemistry. Angiogenesis, lymphangiogenesis, and tumor cell proliferation were assessed by analyzing the expression of respective markers of these phenomena, CD34, D2-40, and Ki-67 after immunohistochemical staining. PROX1 knockdown decreased both umbilical vein endothelial cell invasion and tube formation, down-regulated the expression of VEGF-A and HIF-1α, and up-regulated the expression of angiostatin. Lymphatic endothelial cell invasion and tube formation as well as the expression of VEGF-C were also suppressed by PROX1 knockdown. PROX1 knockdown suppressed tumor cell proliferation, migration, invasion, and epithelial-mesenchymal transition. In contrast, PROX1 overexpression enhanced tumor cell angiogenesis, lymphangiogenesis, proliferation, migration, invasion, and epithelial-mesenchymal transition. Levels of phosphorylated Akt, GSK3β, and MAPK were decreased by PROX1 knockdown and increased by PROX1 overexpression. PROX1 expression positively correlated with tumor size, extent of differentiation, lymphovascular invasion, depth of invasion, lymph node metastasis, stage, and poor survival. The mean microvessel density and Ki-67 labeling index values of PROX1-positive tumors were significantly higher than those of PROX1-negative tumors. However, there was no significant correlation between PROX1 expression and lymphatic vessel density. These results indicate that PROX1 influences tumor progression in colorectal cancer by regulating angiogenesis and tumor cell proliferation.

Associations Between Parameters of Glucose and Lipid Metabolism and Risk of Colorectal Neoplasm

BACKGROUND

Diabetes and dyslipidemia have been linked to an increased risk of colorectal neoplasm (CRN). However, previous studies evaluating these associations have shown inconsistent results, and large-scale studies are few in number.

AIM

To investigate the associations between the parameters of glucose and lipid metabolism and the presence of CRN.

METHODS

A cross-sectional study was performed on 38,490 Korean adults aged ≥30 years undergoing their first colonoscopy as part of routine preventive health care between 2010 and 2011.

RESULTS

The prevalence of overall CRN increased with increasing levels of glucose, hemoglobin A1c (HbA1c), insulin, homeostasis model assessment of insulin resistance (HOMA-IR), triglycerides, total cholesterol, low-density lipoprotein cholesterol (LDL-C), and apolipoprotein B (ApoB) and with decreasing level of apolipoprotein A1 (ApoA1). The adjusted prevalence ratios for overall CRN comparing the fourth with the first quartiles of fasting glucose, HbA1c, insulin, HOMA-IR, triglycerides, total cholesterol, LDL-C, ApoB, and ApoA-1 were 1.83 (95% CI 1.62-2.06), 1.17 (95% CI 1.03-1.33), 1.09 (95% CI 0.97-1.23), 1.22 (95% CI 1.08-1.37), 1.31 (95% CI 1.16-1.48), 1.19 (95 % CI 1.07-1.33), 1.38 (95% CI 1.23-1.54), 1.30 (95% CI 1.14-1.47), and 0.85 (95% CI 0.76-0.95), respectively. There was also a significant association between higher levels of glucose, LDL-C, and ApoB with a higher prevalence of advanced CRN. Moreover, the risk of CRN increased further in cases in which the parameters of glucose metabolism and lipid metabolism worsened simultaneously.

CONCLUSIONS

The levels of parameters of glucose and lipid metabolism are significantly associated with the prevalence of CRN. Altered glucose and lipid metabolism may contribute to the development of CRN.

Initial Results of Multigene Panel Testing for Hereditary Breast and Ovarian Cancer and Lynch Syndrome

Multigene panel testing for hereditary cancer risk has recently become commercially available; however, the impact of its use on patient care is undefined. We sought to evaluate results from implementation of panel testing in a multidisciplinary cancer center. We performed a retrospective review of consecutive patients undergoing genetic testing after initiating use of multigene panel testing at Loma Linda University Medical Center. From February 13 to August 25, 2014, 92 patients were referred for genetic testing based on National Comprehensive Cancer Network guidelines. Testing was completed in 90 patients. Overall, nine (10%) pathogenic mutations were identified: five BRCA1/2, and four in non-BRCA loci. Single-site testing identified one BRCA1 and one BRCA2 mutation. The remaining mutations were identified by use of panel testing for hereditary breast and ovarian cancer. There were 40 variants of uncertain significance identified in 34 patients. The use of panel testing more than doubled the identification rate of clinically significant pathogenic mutations that would have been missed with BRCA testing alone. The large number of variants of uncertain significance identified will require long-term follow-up for potential reclassification. Multigene panel testing provides additional information that may improve patient outcomes.

Glycoprotein A33 deficiency: a new mouse model of impaired intestinal epithelial barrier function and inflammatory disease

The cells of the intestinal epithelium provide a selectively permeable barrier between the external environment and internal tissues. The integrity of this barrier is maintained by tight junctions, specialised cell-cell contacts that permit the absorption of water and nutrients while excluding microbes, toxins and dietary antigens. Impairment of intestinal barrier function contributes to multiple gastrointestinal disorders, including food hypersensitivity, inflammatory bowel disease (IBD) and colitis-associated cancer (CAC). Glycoprotein A33 (GPA33) is an intestinal epithelium-specific cell surface marker and member of the CTX group of transmembrane proteins. Roles in cell-cell adhesion have been demonstrated for multiple CTX family members, suggesting a similar function for GPA33 within the gastrointestinal tract. To test a potential requirement for GPA33 in intestinal barrier function, we generated Gpa33^−/− mice and subjected them to experimental regimens designed to produce food hypersensitivity, colitis and CAC. Gpa33^−/− mice exhibited impaired intestinal barrier function. This was shown by elevated steady-state immunosurveillance in the colonic mucosa and leakiness to oral TRITC-labelled dextran after short-term exposure to dextran sodium sulphate (DSS) to injure the intestinal epithelium. Gpa33^−/− mice also exhibited rapid onset and reduced resolution of DSS-induced colitis, and a striking increase in the number of colitis-associated tumours produced by treatment with the colon-specific mutagen azoxymethane (AOM) followed by two cycles of DSS. In contrast, Gpa33^−/− mice treated with AOM alone showed no increase in sporadic tumour formation, indicating that their increased tumour susceptibility is dependent on inflammatory stimuli. Finally, Gpa33^−/− mice displayed hypersensitivity to food allergens, a common co-morbidity in humans with IBD. We propose that Gpa33^−/− mice provide a valuable model to study the mechanisms linking intestinal permeability and multiple inflammatory pathologies. Moreover, this model could facilitate preclinical studies aimed at identifying drugs that restore barrier function.

Highlighted Article: We show that GPA33, an intestine-specific cell surface protein, plays a role in the maintenance of intestinal barrier function and the prevention of intestinal pathologies such as food hypersensitivity, inflammatory bowel disease and colitis-associated cancer.

Long non-coding RNA LINC01296 is a potential prognostic biomarker in patients with colorectal cancer

Colorectal cancer (CRC), one of the most malignant cancers, is currently the fourth leading cause of cancer deaths worldwide. Recent studies indicated that long non-coding RNAs (lncRNAs) could be robust molecular prognostic biomarkers that can refine the conventional tumor-node-metastasis staging system to predict the outcomes of CRC patients. In this study, the lncRNA expression profiles were analyzed in five datasets (GSE24549, GSE24550, GSE35834, GSE50421, and GSE31737) by probe set reannotation and an lncRNA classification pipeline. Twenty-five lncRNAs were differentially expressed between CRC tissue and tumor-adjacent normal tissue samples. In these 25 lncRNAs, patients with higher expression of LINC01296, LINC00152, and FIRRE showed significantly better overall survival than those with lower expression (P < 0.05), suggesting that these lncRNAs might be associated with prognosis. Multivariate analysis indicated that LINC01296 overexpression was an independent predictor for patients' prognosis in the test datasets (GSE24549, GSE24550) (P = 0.001) and an independent validation series (GSE39582) (P = 0.027). Our results suggest that LINC01296 could be a novel prognosis biomarker for the diagnosis of CRC.

Serrated polyps and their alternative pathway to the colorectal cancer: a systematic review

Colorectal cancer (CRC) is the third most frequently diagnosed cancer in the world. For a long time, only one pathway of colorectal carcinogenesis was known. In recent years, a new “alternative” pathway through serrated adenoma was described. Recent meta-analysis estimated these cancers as about 10% to 30% of all CRCs. Serrated polyps are the second most popular groups of polyps (after conventional adenomas) found during colonoscopy. Serrated polyps of the colon are clinically and molecularly diverse changes that have common feature as crypt luminal morphology characterized by glandular serration. Evidence suggests that subtypes of serrated polyps, particularly TSA and SSA/P, can lead to adenocarcinoma through the serrated pathway. Moreover, the data indicate that the SSA/P are the precursors of colorectal carcinoma by MSI and may be subject to rapid progression to malignancy. An important step to reduce the incidence of CRC initiated by the serrated pathway is to improve the detection of serrated polyps and to ensure their complete removal during endoscopy. Understanding of the so-called serrated carcinogenesis pathway is an important step forward in expanding possibilities in the prevention of CRC.

Global impact of KRAS mutation patterns in FOLFOX treated metastatic colorectal cancer

Background: Colorectal cancer (CRC) is one of the most frequent events in oncology. Advances in molecular understanding of the processes of carcinogenesis have shed light on the fundamental mechanisms of tumorigenesis. Currently, knowledge of the molecular basis of its pathogenesis is being used to improve patient care and devise more rational therapeutics. Still, the role played by the mutation patterns of mutated genes in the clinical outcomes that patients on pharmacological treatment receive remains unclear. In this study, we propose to analyze the different clinical outcomes and disease prognosis of patients with stage IV CRC treated with FOLFOX chemotherapy (fluorouracil, leucovorin, oxaliplatin) based on different Kirsten ras (KRAS) mutation patterns.

Methods: In this cohort study, 148 patients diagnosed with stage IV CRC and treated with FOLFOX were studied between 2008 and 2013. Mutational status of KRAS was determined. Progression-free survival (PFS) and overall survival (OS) were measured, and all deaths were verified. Survival analysis was performed using Kaplan–Meier analysis, comparison among groups was analyzed using the log-rank test, and multivariate analysis was conducted using Cox proportional-hazards regression.

Results: Among a total of 148 patients, 48 (32%) had mutated KRAS, 77% at codon 12 and 23% at codon 13. The PFS was significantly worse in the mutant KRAS patients in comparison to wild type KRAS patients (p < 0.05). The OS did not show significant differences between the two groups. Multivariate analysis showed KRAS mutation as an independent negative prognostic factor for PFS. Among the various subtypes of KRAS mutation, G12D was significantly associated with a poor prognosis in PFS (p = 0.02).

Conclusion: In our population, the KRAS mutation had an adverse impact on the prognosis for stage IV CRC patients treated with the FOLFOX regimen.

Myeloid cell leukemia-1 is associated with tumor progression by inhibiting apoptosis and enhancing angiogenesis in colorectal cancer

Myeloid cell leukemia-1 (Mcl-1) is a highly expressed anti-apoptotic Bcl-2 protein in cancer. Therefore, inhibition of its expression induces apoptosis in cancer cells and enhances sensitivity to cancer treatment. The aims of this study were to evaluate whether Mcl-1 affects the oncogenic behaviors of colorectal cancer cells, and to document the relationship of its expression with various clinicopathological parameters in colorectal cancer. Mcl-1 knockdown induced apoptosis by activating cleaved caspase-3 and -9, and increasing the expression of the pro-apoptotic protein, PUMA. Mcl-1 knockdown induced cell cycle arrest by decreasing cyclin D1, CDK4 and 6, and by increasing p27 expression. Mcl-1 knockdown decreased both endothelial cell invasion and tube formation, and decreased the expression of VEGF. The phosphorylation level of STAT3 was decreased by Mcl-1 knockdown. The mean apoptotic index value of Mcl-1 positive tumors was significantly lower than that of Mcl-1 negative tumors. The mean microvessel density value of Mcl-1 positive tumors was significantly higher than that of negative tumors. Mcl-1 expression was significantly increased in colorectal cancer, also associated with tumor stage, lymph node metastasis, and poor survival. These results indicate Mcl-1 is associated with tumor progression through its inhibition of apoptosis and enhancement of angiogenesis in colorectal cancer.