Predictive and prognostic factors in colorectal cancer: a personalized approach

Improved Accuracy of Lymph Node Staging and Long-Term Survival Benefit in Colorectal Cancer With Ex Vivo Arterial Methylene Blue Infiltration

Introduction:Ex vivo methylene blue (MB) injection into the main supplying arteries of the colorectal specimen after surgical removal is an uncomplicated technique to support lymph node harvest during pathological evaluation. The primary aim of this randomized, interventional, bicentric trial was to evaluate the impact of MB injection on lymph node yield, with secondary aims assessing the accuracy of lymph node staging and the effect on 5-year overall survival for patients undergoing resection of colorectal cancer.

Methods: In the study period between December 2013 and August 2015, 200 colorectal resections were performed at two independent onco-surgery centers of Hungary. Following surgical resection, each specimen was randomly assigned either to the control (standard pathological work-up) or to the MB staining group before formaldehyde fixation. Patient-level surgical and clinical data were retrieved from routinely collected clinical datasets. Survival status data were obtained from the National Health Insurance Fund of Hungary.

Results: A total of 162 specimens, 82 in the control and 80 in the MB groups, were included for analysis. Baseline characteristics were equally distributed among study groups, except for specimen length. Both the median of total number of lymph nodes retrieved (control 11 ± 8 [0–33] nodes vs. MB 14 ± 6 [0–42] nodes; p < 0.01), and the ratio of cases with at least 12 removed lymph nodes (36/82, 43.9% vs. 53/80, 66.3%; p < 0.01) were higher in the MB group. The rate of accurate lymph node staging was non-significantly improved. As for rectal cancer, nodal staging accuracy (16/31, 51.6% vs. 23/30, 76.7%; p = 0.04) and the proportion with minimum 12 lymph node retrieval (7/31, 22.6%, vs. 18/30, 60%; p < 0.01) was improved by MB injection. In Mantel–Cox regression, a statistically significant survival benefit with methylene blue injection at 5 years post-surgery was proven (51.2% vs. 68.8%; p = 0.04).

Conclusion: In our experience, postoperative ex vivo arterial methylene blue injection appears to be an uncomplicated technique, improving lymph node yield and decreasing the chance of insufficient nodal staging. The technique might also associate with a 5-year overall survival benefit.

The role of the PTEN/mTOR axis in clinical response of rectal cancer patients

BACKGROUND

Preoperative chemoradiotherapy has long been accepted as a method to improve survival and lifetime quality of rectal cancer patients. However, physiologic effects of these therapies largely depend on the resistance of cells to the radiation, type of chemotherapeutic agents and individual responses. As one of the signaling cascades involved in chemo- or radiation- resistance, the present study focused on several proteins involved in pTEN/Akt/mTOR pathway to explore their prognostic significance.

MATERIALS AND METHODS

Samples from advanced stage rectal cancer patients were analyzed to detect expression levels of pTEN/Akt/mTOR pathway related proteins pTEN, mLST8, REDD1, BNIP3, SAG and NOXA, together with p53, by RT-qPCR. Kaplan-Meier analysis was used to assess expression-survival relation and correlations among all proteins and clinicopathological features were statistically analyzed.

RESULTS

Except p53, none of the proteins showed prognostic significance. High p53 expression presented clear impact on overall survival and disease free survival. It was also significantly related to pathologic complete response. p53 showed high correlation to local recurrence as well. On the other hand, strong correlation was observed with PTEN expression and tumor response, but not with survival. High associations were also observed between mLST8/REDD1, PTEN and NOXA, confirming their role in the same cascade.

CONCLUSION

The contentious role of p53 as a prognostic biomarker in colorectal cancer was further affirmed, while PTEN and REDD1 could be suggested as potential candidates. Additionally, NOXA emerges as a conjunctive element for different signaling pathways.

Biomarkers (mRNAs and Non-Coding RNAs) for the Diagnosis and Prognosis of Colorectal Cancer - From the Body Fluid to Tissue Level

In recent years, the diagnosis and treatment of colorectal cancer (CRC) have been continuously improved, but the mortality rate continues to be high, especially in advanced patients. CRC patients usually have no obvious symptoms in the early stage and are already in the advanced stage when they are diagnosed. The 5-year survival rate is only 10%. The blood markers currently used to screen for CRC, such as carcinoembryonic antigen and carbohydrate antigen 19-9, have low sensitivity and specificity, whereas other methods are invasive or too expensive. As a result, recent research has shifted to the development of minimally invasive or noninvasive biomarkers in the form of body fluid biopsies. Non-coding RNA molecules are composed of microRNAs, long non-coding RNAs, small nucleolar RNAs, and circular RNAs, which have important roles in the occurrence and development of diseases and can be utilized for the early diagnosis and prognosis of tumors. In this review, we focus on the latest findings of mRNA-ncRNA as biomarkers for the diagnosis and prognosis of CRC, from fluid to tissue level.

Low expression of Talin1 is associated with advanced pathological features in colorectal cancer patients

To explore the proper prognostic markers for the likelihood of metastasis in CRC patients. Seventy-seven fresh CRC samples were collected to evaluate the mRNA level of the selected marker using Real-time PCR. Moreover, 648 formalin-fixed paraffin-embedded CRC tissues were gathered to evaluate protein expression by immunohistochemistry (IHC) on tissue microarrays. The results of Real-Time PCR showed that low expression of Talin1 was significantly associated with advanced TNM stage (p = 0.034) as well as gender (p = 0.029) in mRNA levels. Similarly, IHC results indicated that a low level of cytoplasmic expression of Talin1 was significantly associated with advanced TNM stage (p = 0.028) as well as gender (p = 0.009) in CRC patients. Moreover, decreased expression of cytoplasmic Talin1 protein was found to be a significant predictor of worse disease-specific survival (DSS) (p = 0.011) in the univariate analysis. In addition, a significant difference was achieved (p = 0.039) in 5-year survival rates of DSS: 65% for low, 72% for moderate, and 88% for high Talin1 protein expression. Observations showed that lower expression of Talin1 at both the gene and protein level may drive the disparity of CRC patients’ outcomes via worse DSS and provide new insights into the development of progression indicators because of its correlation with increased tumor aggressiveness.

Clinical value evaluation of serum markers for early diagnosis of colorectal cancer

BACKGROUND

Early screening for colorectal cancer (CRC) is important in clinical practice. However, the currently methods are inadequate because of high cost and low diagnostic value.

AIM

To develop a new examination method based on the serum biomarker panel for the early detection of CRC.

METHODS

Three hundred and fifty cases of CRC, 300 cases of colorectal polyps and 360 cases of normal controls. Combined with the results of area under curve (AUC) and correlation analysis, the binary Logistic regression analysis of the remaining indexes which is in accordance with the requirements was carried out, and discriminant analysis, classification tree and artificial neural network analysis were used to analyze the remaining indexes at the same time.

RESULTS

By comparison of these methods, we obtained the ability to distinguish CRC from healthy control group, malignant disease group and benign disease group. Artificial neural network had the best diagnostic value when compared with binary logistic regression, discriminant analysis, and classification tree. The AUC of CRC and the control group was 0.992 (0.987, 0.997), sensitivity and specificity were 98.9% and 95.6%. The AUC of the malignant disease group and benign group was 0.996 (0.992, 0.999), sensitivity and specificity were 97.4% and 96.7%.

CONCLUSION

Artificial neural network diagnosis method can improve the sensitivity and specificity of the diagnosis of CRC, and a novel assistant diagnostic method was built for the early detection of CRC.

Silencing of synaptotagmin 13 inhibits tumor growth through suppressing proliferation and promoting apoptosis of colorectal cancer cells

The treatment of colorectal cancer is currently hampered by the lack of early detection technology. The identification of molecular biomarkers for colorectal cancer is crucial for improving prognosis. Synaptotagmin (SYT) 13 has been reported to be associated with several human tumors, but its role in colorectal cancer remains elusive. In the present study, immunohistochemistry was utilized to detect the expression of SYT13 in colorectal cancer tissues and cells. MTT, colony formation, wound healing and Transwell assays were conducted to evaluate the effect of SYT13 knockdown on the biological behavior of RKO and HCT116 cells. Cell apoptosis and cell cycle profiles were detected by FACS. A mouse xenograft model was constructed to investigate the effect of SYT13 on colorectal cancer in vivo. The results indicated that SYT13 was upregulated in colorectal tumor tissues compared with paracancerous tissues. Silencing of SYT13 inhibited the proliferation, colony formation, migration and invasion ability of RKO and HCT116 cells. Moreover, SYT13 knockdown arrested the cell cycle in the G2 phase, thus inducing cell apoptosis. The in vivo experiments also demonstrated the inhibitory effect of SYT13 on tumor growth. In conclusion, the present study demonstrated that SYT13 may act as a promoter in the development and progression of colorectal cancer and, therefore, may be of value as a target for the development of novel treatment strategies.

Tumor budding in colorectal carcinoma: An institutional interobserver reliability and prognostic study of colorectal adenocarcinoma cases

BACKGROUND

Colorectal carcinomas are one of the most commonly diagnosed malignancies. There are many prognostic factors relating to clinical course and disease progression, including tumor stage, metastasis, and tumor budding. In 2016, the International Tumor Budding Consensus Conference (ITBCC) created a system to uniformly assess tumor budding. This system includes a 3-tier system for the grading of tumor budding. In the past, there lacked uniform consensus, however the general grading practice was based on a 2-tiered system. Given that tumor budding is considered to have prognostic value, the accuracy and reproducibility of its assessment is vital. Our study aims to look at interobserver agreement in the scoring of tumor budding.

DESIGN

A total of 233 cases of colorectal carcinoma diagnosed in our health system were retrospectively analyzed and routine H&E stained slides of these cases were collected. A representative slide for tumor budding was selected per case. Four investigators with different levels of experience and expertise evaluated the selected slide of each case for tumor budding. Scoring was based on the ITBCC protocol. Clinico-pathological data was collected for each case and analyzed with tumor budding scores. Tumor budding scores per individual investigator and consensus tumor budding score were compared to patient and tumor characteristics including patient survival, tumor grade, tumor stage, and lymph node status.

RESULTS

Inter-observer agreement was calculated using Gwet's Agreement Coefficient (AC₁) and associated 95% confidence intervals was used to compare the ratings made by 4 pathologists. Overall, there was variation among pathologists in tumor budding score (Gwet's agreement coefficient = 0.25 and 0.326 for 3-tier and 2-tier grading system, respectively). Results show higher reliability with the 2-tier system compared to the 3-tier system. Tumor stage was significantly associated with budding score for all individual investigators and the consensus value (p value < 0.001).

CONCLUSION

There is low inter-observer agreement in the assessment of tumor budding in colorectal carcinoma. This suggests that it is difficult to uniformly grade tumor budding and that our classification system needs improvement. We found that the older 2-tier system (Hase et al.) results in slightly higher inter-observer agreement than the recently proposed 3-tier grading system (ITBCC, 2016), though both systems lead to suboptimal agreement. Worth noting is that observers with subspecialty GI training and more work experience had higher inter-observer agreement. Our results showed that subspecialty training tends to increase agreement more than overall work experience. In addition, our exploratory results showed that there is an association of tumor budding score to tumor stage. While increasing refinement in classification, the 3-tiered system resulted in decreased agreement in tumor budding assessment. Clearly, there is more work to be done in the identification and quantification of tumor buds.

Tumor Budding in Colorectal Carcinoma Showing a Paradoxical Mitotic Index (Via PHH3) With Possible Association to the Tumor Stromal Microenvironment

BACKGROUND

Colorectal carcinomas (CC) are one of the most commonly diagnosed malignancies. Tumor budding (the histologic process of dissociation that occurs at the invasive margin of colorectal cancer), has significant prognostic implications, in that higher tumor budding is associated with adverse histopathologic and clinical outcomes. Because of this prognostic significance, more research is needed to further understand the pathologic and immunohistochemical (IHC) associations pertaining to this important prognostic variable. In this study, we will further evaluate selective clinopathologic and IHC variables with possible association to tumor budding.

DESIGN

A total of 234 cases of CC diagnosed in our health system were retrospectively reviewed and routine hematoxylin and eosin-stained slides of these cases were collected. A representative slide for tumor budding was selected per case and selective IHC staining was performed. Clinicopathologic data were collected for each case and analyzed in relation to tumor budding scores. In exploratory analyses, tumor budding scores per individual investigator and consensus tumor budding scores were compared with selected IHC stains (MLH1, PMS2, and PHH3) as well as numerous clinicopathologic variables.

RESULTS

We found a paradoxical association between tumor budding and mitosis score using PHH3 immunostaining in univariate and multivariable analysis. Furthermore, patients with intact nuclear expression for MLH1 and/or PMS2 are more likely to have higher tumor budding compared with patients with lost expression. For multivariable analysis, the following covariates were significantly associated with higher tumor budding: the presence of lymphovascular invasion, higher pathologic tumor stage, and finally infiltrating border was more likely to be associated with higher tumor budding compared with cases with a pushing border. Regarding nonmucinous versus mucinous CC, nonmucinous adenocarcinoma (MCA) was more likely to be associated with higher tumor budding compared with MCA.

CONCLUSION

Numerous clinicopathologic variables were found to be associated with tumor budding including lymphovascular invasion, tumor stage, infiltrating tumor border, non-MCA was more likely to be associated with higher tumor budding compared with MCA, possibly related to MUC-2 and MSI. Furthermore, regarding the paradoxical association between tumor budding and mitosis score using a PHH3 immunostaining (high tumor budding having lower mitosis), this is possibly related to the tumoral stomal microenvironment and cancer associated fibroblasts. An idea for a future study would be to look at the maturity of cancer-associated fibroblasts (immature vs. mature) and the tumoral stroma microenvironment, with regards to markers of tumor aggressiveness such as mitosis. In addition, we found that patients with intact nuclear expression for MLH1 and/or PMS2 were more likely to have higher tumor budding compared with patients with lost expression, possibly related to mismatch repair CC's not being as reliant on tumor budding. Future research will hopefully concede further insight into the variables that affect tumor budding, especially regarding the tumoral microenvironment and variations between different patient populations, inclusive of patients lacking activity of the mismatch repair. Ultimately, this will allow for better prognostic information, and more precise treatment modalities.

n-6 Linoleic Acid Induces Epigenetics Alterations Associated with Colonic Inflammation and Cancer

The farnesoid-X-receptor (FXR) protects against inflammation and cancer of the colon through maintenance of intestinal bile acid (BA) homeostasis. Conversely, higher levels of BA and cyclooxygenase-2 (COX-2) are risk factors for inflammation and cancer of the colon. In the United States, n-6 linoleic acid (LA) is the most commonly used dietary vegetable fat. Metabolism of n-6 fatty acids has been linked to a higher risk of intestinal cancer. The objectives of this study were to investigate in colonic mucosa the effects of a high-fat diet rich in LA (n-6HFD) on CpG methylation of Fxr and prostaglandin-endoperoxide synthase-2 (Ptsg-2) genes, and the impact on the expression of tumor suppressor adenomatous polyposis Coli (Apc) and proliferative cyclin D1 (Ccnd1) genes. Weaned C57BL/6J male mice were fed for 6 weeks either an n-6HFD containing 44% energy (44%E) from 22% safflower oil (SO, 76% LA by weight) or a 13% energy (13%E) control diet (Control) from SO (5% by weight). Mice fed the n-6HFD had reduced (60%) Fxr promoter CpG methylation and increased (~50%) Fxr mRNA. The expression of FXR-target ileal bile acid-binding protein (Ibabp), small heterodimer protein (Shp), and anti-inflammatory peroxisome proliferator-activated-γ1 genes was increased. The n-6HFD reduced Ptgs-2 CpG methylation, increased the expression of Cox-2, and increased Apc CpG methylation in colonic mucosa. Accordingly, reduced expression of Apc was coupled to accumulation of c-JUN and Ccnd1, respectively cofactor and gene targets for the β-catenin/Wnt signaling pathway. Finally, the n-6HFD reduced the expression of histone deacetylase-1 while favoring the accumulation of acetylated histone 3. We conclude that an n-6HFD epigenetically modifies Fxr, leading to the activation of downstream factors that participate in BA homeostasis. However, epigenetic activation of Ptsg-2 coupled with silencing of Apc and accumulation of C-JUN and Ccnd1 may increase the risk of inflammation and cancer of the colon.

PIWI-interacting RNA-54265 is oncogenic and a potential therapeutic target in colorectal adenocarcinoma

Although PIWI-interacting RNAs (piRNAs) have recently been linked to human diseases, their roles and functions in malignancies remain unclear. This study aimed to investigate the significance of some piRNAs in colorectal cancer (CRC). Methods: We first analyzed the expression profile of piRNAs in CRC using the TCGA and GEO databases. The top 20 highly expressed piRNAs were selected and tested in our CRC tumor and non-tumor tissue samples. We then examined the relevance of the significantly differentially expressed piRNA to the CRC outcomes in 218 patients receiving postoperative chemotherapy and 317 patients receiving neoadjuvant chemotherapy. A series of biochemical and molecular biological assays were conducted to elucidate the functional mechanism of a piRNA of interest in CRC. Furthermore, experiments with mice xenografts were performed to evaluate the therapeutic effect of an inhibitor specific to the piRNA. Results: We found that among the examined 20 piRNAs, only piRNA-54265 was overexpressed in CRC compared with non-tumor tissues and higher levels in tumor or in serum were significantly associated with poor survival in patients. Functional assays demonstrated that piRNA-54265 binds PIWIL2 protein and this is necessary for the formation of PIWIL2/STAT3/phosphorylated-SRC (p-SRC) complex, which activates STAT3 signaling and promotes proliferation, metastasis and chemoresistance of CRC cells. Treatment with a piRNA-54265 inhibitor significantly suppressed the growth and metastasis of implanted tumors in mice. Conclusion: These results indicate that piRNA-54265 is an oncogenic RNA in CRC and thus might be a therapeutic target.

High expression of GPR116 indicates poor survival outcome and promotes tumor progression in colorectal carcinoma

Previous studies have found that G-protein-coupled receptor 116 (GPR116) is a regulator of breast cancer metastasis. However, the role of GPR116 in colorectal carcinoma (CRC) carcinogenesis and progression is unknown. In this study, We found GPR116 expression was significantly up-regulated in CRC specimens compared with corresponding non-cancerous tissues. Increased GPR116 expression in CRC was correlated with histological differentiation and distant metastasis. In addition, high expression of GPR116 was significantly associated with poor overall survival of CRC patients, which was also confirmed by GSE14333, GSE17536 and GSE33113 datasets from the Gene Expression Omnibus (GEO). Furthermore, we demonstrated that the ability of proliferation and invasion of CRC cell lines HCT116 and LOVO was markedly reduced after transfected with siRNA-GPR116. Meanwhile, GPR116 may drive EMT in CRC cells through AKT/EKR signaling pathway, resulting in metastasis. Thus, GPR116 may be a novel reliable prognostic indicator and a risk factor in CRC progression.

Solute carrier family 34 member 2 overexpression contributes to tumor growth and poor patient survival in colorectal cancer

Solute carrier family 34 member 2 (SLC34A2) is a well-known sodium-dependent phosphate transporter that has recently been linked to cancer development. However, its specific oncogenic role remains controversial in numerous human malignancies, and is currently unknown in colorectal cancer (CRC). Therefore, in this study we firstly used Oncomine database to determine its expression in cancer tissues and found it is overexpressed in thyroid, ovarian and renal cancer, while it is opposite in lung, breast and pancreas cancer. Using qRT-PCR and western blot, we then demonstrated its overexpression in CRC tissues as compared with adjacent normal tissues (n = 20). In a retrospective cohort enrolling 190 CRC patients, we proved its expression was significantly correlated with N stage. Furthermore, high SLC34A2 expression is associated with higher postoperative metastasis rate and serves as an independent adverse factor affecting patient prognosis. In subgroup analysis, SLC34A2 expression could stratify the patient prognosis in stage II and III CRC, but failed in stage IV CRC. In cellular assays in vitro, knockdown of SLC34A2 dramatically inhibited the proliferation and colony formation, induced the apoptosis and arrests the cell cycle progression of HCT-116 CRC cells. In cellular assays in vivo, knockdown of SLC34A2 significantly inhibited the growth of xenografts, decreasing Ki-67 and proliferating cell nuclear antigen (PCNA) expression and increasing apoptosis rate. Taken together, our study indicates SLC34A2 plays a crucial promoting role in CRC development and therefore has great potential to be further developed as a reliable biomarker for CRC diagnosis and treatment.

Comparison of Basic and Ensemble Data Mining Methods in Predicting 5-Year Survival of Colorectal Cancer Patients

INTRODUCTION

Colorectal cancer (CRC) is one of the most common malignancies and cause of cancer mortality worldwide. Given the importance of predicting the survival of CRC patients and the growing use of data mining methods, this study aims to compare the performance of models for predicting 5-year survival of CRC patients using variety of basic and ensemble data mining methods.

METHODS

The CRC dataset from The Shahid Beheshti University of Medical Sciences Research Center for Gastroenterology and Liver Diseases were used for prediction and comparative study of the base and ensemble data mining techniques. Feature selection methods were used to select predictor attributes for classification. The WEKA toolkit and MedCalc software were respectively utilized for creating and comparing the models.

RESULTS

The obtained results showed that the predictive performance of developed models was altogether high (all greater than 90%). Overall, the performance of ensemble models was higher than that of basic classifiers and the best result achieved by ensemble voting model in terms of area under the ROC curve (AUC= 0.96).

CONCLUSION

AUC Comparison of models showed that the ensemble voting method significantly outperformed all models except for two methods of Random Forest (RF) and Bayesian Network (BN) considered the overlapping 95% confidence intervals. This result may indicate high predictive power of these two methods along with ensemble voting for predicting 5-year survival of CRC patients.

Low-grade slightly elevated and polypoid colorectal adenomas display differential β-catenin-TCF/LEF activity, c-Myc, and cyclin D1 expression

AIM

To comparatively investigate the cellular and molecular characteristics of low-grade slightly elevated adenomas and polypoid adenomas.

METHODS

Colorectal tumors were collected from 24 patients with slightly elevated adenomas and 23 patients with polypoid adenomas. Five commonly mutated genes (APC, BRAF, KRAS, NRAS, and PIK3CA) were selected for mutational analysis. Paraffin-embedded tumor sections were used to calculate the apoptotic index (AI) and Ki-67 labeling index (KLI). Two pure colorectal epithelial cell lines were created by pooling the slightly elevated and polypoid tumors. Western blots, luciferase assays for β-catenin-T-cell factor protein/β-catenin-lymphoid enhancer factor (β-catenin-TCF/LEF)-driven transcriptional activity, and caspase activity assays were conducted on the two cell lines.

RESULTS

Slightly elevated lesions showed a significantly lower APC mutational frequency and a significantly higher KRAS mutational frequency (both P < 0.05). Slightly elevated lesions showed a significantly lower AI (P < 0.05). β-catenin and β-catenin-TCF/LEF-driven transcriptional activity was significantly upregulated in slightly elevated lesions (both P < 0.05). In slightly elevated lesions, c-Myc was significantly downregulated, while cyclin D1 was significantly upregulated (both P < 0.05). β-catenin-TCF/LEF-driven transcriptional activity was negatively correlated with c-Myc (ρ = -0.78). Slightly elevated lesions displayed significant Bcl-2 and Bcl-xL upregulation (both P < 0.05) along with significant decreases in caspase-9 and caspase-3 activity (both P < 0.05). c-Myc was negatively correlated with Bcl-2 and Bcl-xL (ρ = -0.74 and -0.78, respectively).

CONCLUSION

The lower apoptotic activity of low-grade slightly elevated adenomas can be partly attributed to upregulated β-catenin pathway activity and downregulated c-Myc expression.

Prognostic Significance of Mucinous Histologic Subtype on Oncologic Outcomes in Patients With Colorectal Cancer

Purpose

Mucinous adenocarcinomas account for about 10% of all colorectal cancers. This study aimed to investigate the prognostic impact of mucinous histologic subtype on oncologic outcomes in patients with colorectal cancer.

Methods

This retrospective study was performed at two large tertiary university hospitals. We analyzed the characteristics, prognostic factors, and survival of patients with colorectal cancer who were treated and followed up between 2000 and 2013.

Results

Totally, 144 of 1,268 patients with a colorectal adenocarcinoma (11.4%) had mucinous histologic subtype. Statistically significant results found in this research are as follows: Mucinous histologic subtype tended to present in younger patients and to have larger tumor size, higher histologic grade, higher node stage, larger number of positive nodes, and higher rate of perineural invasion compared to nonmucinous histologic subtype. On the univariate analysis, mucinous subtype was a prognostic factor for disease-free and overall survival. On the multivariate analysis, primary tumor location, node stage and lymphatic-vascular invasion were independent prognostic factors for the local control rate. Rectal tumor location, higher disease stage, tumor grade II, and presence of lymphatic-vascular invasion had negative influences on disease-free survival, as did rectal tumor location, higher disease stage and presence of lymphatic-vascular invasion on overall survival.

Conclusion

Mucinous histologic subtype was associated with some adverse pathologic features in patients with colorectal cancer; however, it was not an independent prognostic factor for oncologic outcome.

Predictive and prognostic biomarkers in colorectal cancer: A systematic review of recent advances and challenges

BACKGROUND

Colorectal cancer (CRC) is one of the leading cause of cancer deaths worldwide. Since CRC is largely asymptomatic until alarm features develop to advanced stages, the implementation of the screening programme is very much essential to reduce cancer incidence and mortality rates. CRC occurs predominantly from accumulation of genetic and epigenetic changes in colon epithelial cells, which later gets transformed into adenocarcinomas.

SCOPE OF REVIEW

The current challenges of screening paradigm and diagnostic ranges are from semi-invasive methods like colonoscopy to non-invasive stool-based test, have resulted in over-diagnosis and over-treatment of CRC. Hence, new screening initiatives and deep studies are required for early diagnosis of CRC. In this regard, we not only summarise current predictive and prognostic biomarkers with their potential for diagnostic and therapeutic applications, but also describe current limitations, future perspectives and challenges associated with the progression of CRC.

MAJOR CONCLUSIONS

Currently many potential biomarkers have already been successfully translated into clinical practice eg. Fecal haemoglobin, Carcinoembryonic antigen (CEA) and CA19.9, although these are not highly promising diagnostic target for personalized medicine. So there is a critical need for reliable, minimally invasive, highly sensitive and specific genetic markers of an individualised and optimised patient treatment at the earliest disease stage possible.

GENERAL SIGNIFICANCE

Identification of a new biomarker, or a set of biomarkers to the development of a valid, and clinical sensible assay that can be served as an alternative tool for early diagnosis of CRC and open up promising new targets in therapeutic intervention strategies.

Apoptotic pathways as a therapeutic target for colorectal cancer treatment

Colorectal cancer is the second leading cause of death from cancer among adults. The disease begins as a benign adenomatous polyp, which develops into an advanced adenoma with high-grade dysplasia and then progresses to an invasive cancer. Appropriate apoptotic signaling is fundamentally important to preserve a healthy balance between cell death and cell survival and in maintaining genome integrity. Evasion of apoptotic pathway has been established as a prominent hallmark of several cancers. During colorectal cancer development, the balance between the rates of cell growth and apoptosis that maintains intestinal epithelial cell homeostasis gets progressively disturbed. Evidences are increasingly available to support the hypothesis that failure of apoptosis may be an important factor in the evolution of colorectal cancer and its poor response to chemotherapy and radiation. The other reason for targeting apoptotic pathway in the treatment of cancer is based on the observation that this process is deregulated in cancer cells but not in normal cells. As a result, colorectal cancer therapies designed to stimulate apoptosis in target cells would play a critical role in controlling its development and progression. A better understanding of the apoptotic signaling pathways, and the mechanisms by which cancer cells evade apoptotic death might lead to effective therapeutic strategies to inhibit cancer cell proliferation with minimal toxicity and high responses to chemotherapy. In this review, we analyzed the current understanding and future promises of apoptotic pathways as a therapeutic target in colorectal cancer treatment.

The chemokine CXCL9 expression is associated with better prognosis for colorectal carcinoma patients

The chemokine CXCL9 has been demonstrated to play an important role in the development of human malignancies. However, its prognostic significance in cancer patients remains unclear and less is known about its role in colonrectal carcinoma (CRC) patients. In this study, we found that the relative mRNA expression level of CXCL9 in primary colorectal tumor tissues was significantly higher than that in corresponding normal colon tissues. CXCL9 protein expression was also detected in 102 of 130 primary CRC patients by immunochemistry. Thus, CXCL9 might play a vital role in the progression of colorectal cancer. By analyzing the correlation between clinicopathological factors of patients and expression of CXCL9 protein, we showed that the expression of CXCL9 was significantly associated with tumor differentiation, tumor invasion, lymph node metastasis, distant metastasis, and vascular invasion, but not with other factors of CRC patients including age, gender, tumor location and tumor size. Furthermore, by performing Kaplan-Meier method as well as Cox's univariate and multivariate hazard regression model, we found that the higher the CXCL9 expression, the higher overall survival rate was observed, and CXCL9 expression was a significant independent prognostic factor for CRC patients. Therefore, CXCL9 is a useful predictor of better clinical outcome in CRC patients.

An EGFR targeted PET imaging probe for the detection of colonic adenocarcinomas in the setting of colitis

Colorectal cancer is a serious complication associated with inflammatory bowel disease, often indistinguishable by screening with conventional FDG PET probes. We have developed an alternative EGFR-targeted PET imaging probe that may be used to overcome this difficulty, and successfully assessed its utility for neoplastic lesion detection in preclinical models. Cetuximab F(ab′)2 fragments were enzymatically generated, purified, and DOTA-conjugated. Radiolabeling was performed with ⁶⁷Ga for cell based studies and ⁶⁴Cu for in vivo imaging. Competitive binding studies were performed on CT26 cells to assess affinity (K_D) and receptors per cell (B_max). In vivo imaging using the EGFR targeted PET probe and ¹⁸F FDG was performed on CT26 tumor bearing mice in both control and dextran sodium sulfate (DSS) induced colitis settings. Spontaneous adenomas in genetically engineered mouse (GEM) models of colon cancer were additionally imaged. The EGFR imaging agent was generated with high purity (> 98%), with a labeling efficiency of 60 ± 5% and ≥99% radiochemical purity. The K_D was 6.6 ± 0.7 nM and the B_max for CT26 cells was 3.3 ± 0.1 × 10⁶ receptors/cell. Target to background ratios (TBR) for CT26 tumors compared to colonic uptake demonstrated high values for both ¹⁸F-FDG (3.95 ± 0.13) and the developed ⁶⁴Cu-DOTA-cetuximab-F(ab′)2 probe (4.42 ± 0.11) in control mice. The TBR for the EGFR targeted probe remained high (3.78 ± 0.06) in the setting of colitis, while for ¹⁸F FDG, this was markedly reduced (1.54 ± 0.08). Assessment of the EGFR targeted probe in the GEM models demonstrated a correlation between radiotracer uptake in spontaneous colonic lesions and the EGFR staining level ex vivo. A clinically translatable PET imaging probe was successfully developed to assess EGFR. The imaging agent can detect colonic tumors with a high TBR for detection of in situ lesions in the setting of colitis, and opens the possibility for a new approach for screening high-risk patients.

Zinc-finger protein X-linked is a novel predictor of prognosis in patients with colorectal cancer

Zinc-finger protein X-linked (ZFX) has been demonstrated to play an important role in the development of human malignancies. However, its prognostic significance in cancer patients remains unclear and less is known about its role in colorectal cancer (CRC). In this study, we found that the expression of ZFX in CRC tissues was significantly higher than that in corresponding normal tissues by quantitative real-time polymerase chain reaction and Western blot. Using immunohistochemistry, we explored the associations between protein expression of ZFX and clinicopathological parameters in 120 CRC cases. The results showed that ZFX expression was significantly associated with tumor differentiation (P = 0.022), tumor size (P = 0.037), tumor invasion (P = 0.027), lymph node metastasis (P = 0.042), distant metastasis (P = 0.011), and Dukes' classification (P = 0.028). Moreover, according to Kaplan-Meier model, patients with high expression of ZFX had a significantly poorer prognosis compared to those with low expression of ZFX. Multivariate analysis suggested that high expression of ZFX was an independent prognostic factor for CRC patients. In conclusion, our findings for the first time demonstrated that ZFX expression may be associated with the progress of CRC and suggested that ZFX has the potential value to be an effective prognostic predictor for CRC patients.

Clinical significance of serum ADP-ribosylation and NAD glycohydrolase activity in patients with colorectal cancer

The objective of this study was to evaluate the clinical significance of serum ADP-ribosylation and NAD glycohydrolase activity in patients with colorectal cancer (CRC). A total of 108 patients with CRC who underwent curative surgery and 20 healthy volunteers were enrolled in this study. ADP-ribosylation and NAD glycohydrolase activity levels were determined. The association of ADP-ribosylation and NAD glycohydrolase with clinical and laboratory factors and their impact on overall survival (OS) and disease free survival (DFS) were shown. The preoperative ADP-ribosylation and NAD glycohydrolase activity levels were significantly higher in patients with CRC than in the control group (p<0.001). ADP-ribosylation and NAD glycohydrolase activity levels were correlated with tumor stage (p=0.05, p=0.001), stage of disease (p<0.001, p<0.001), serum CEA level (p<0.001, p<0.001), and site of lesion (p<0.001, p<0.001), respectively. Patients with high ADP-ribosylation had significantly unfavorable OS and DFS compared with those with lower levels (p<0.001, p<0.001), respectively. Moreover, the patients with high NAD glycohydrolase activity showed significantly worse OS and DFS rates, similar to ADP-ribosylation. Serum levels of ADP-ribosylation and NAD glycohydrolase activity correlate well with tumor stage, stage of disease, serum CEA level, and site of lesion. In conclusion, elevated levels of preoperative ADP-ribosylation and NAD glycohydrolase levels in serum are associated with poor prognosis in patients with CRC.

Mechanistic aspects of COX-2 expression in colorectal neoplasia

The cyclooxygenase-2 (COX-2) enzyme catalyzes the rate-limiting step of prostaglandin formation in pathogenic states and a large amount of evidence has demonstrated constitutive COX-2 expression to be a contributing factor promoting colorectal cancer (CRC). Various genetic, epigenetic, and inflammatory pathways have been identified to be involved in the etiology and development of CRC. Alteration in these pathways can influence COX-2 expression at multiple stages of colon carcinogenesis allowing for elevated prostanoid biosynthesis to occur in the tumor microenvironment. In normal cells, COX-2 expression levels are potently regulated at the post-transcriptional level through various RNA sequence elements present within the mRNA 3' untranslated region (3'UTR). A conserved AU-rich element (ARE) functions to target COX-2 mRNA for rapid decay and translational inhibition through association with various RNA-binding proteins to influence the fate of COX-2 mRNA. Specific microRNAs (miRNAs) bind regions within the COX-2 3'UTR and control COX-2 expression. In this chapter, we discuss novel insights in the mechanisms of altered post-transcriptional regulation of COX-2 in CRC and how this knowledge may be used to develop novel strategies for cancer prevention and treatment.

Generation and external validation of a tumor-derived 5-gene prognostic signature for recurrence of lymph node-negative, invasive colorectal carcinoma

BACKGROUND: One in 4 patients with lymph node-negative, invasive colorectal carcinoma (CRC) develops recurrent disease after undergoing curative surgery, and most die of advanced disease. Predicting which patients will develop a recurrence is a significantly growing, unmet medical need. METHODS: Archival formalin-fixed, paraffin-embedded (FFPE) primary adenocarcinoma tissues obtained at surgery were retrieved from 74 patients with CRC (15 with stage I disease and 59 with stage II disease) for Training/Test Sets. In addition, FFPE tissues were retrieved from 49 patients with stage I CRC and 215 patients with stage II colon cancer for an External Validation (EV) Set (n = 264) from 18 hospitals in 4 countries. No patients had received neoadjuvant/adjuvant therapy. Proprietary genetic programming analysis of expression profiles for 225 prespecified tumor genes was used to create a 36-month recurrence risk signature. RESULTS: Using reverse transcriptase-polymerase chain reaction, a 5-gene rule correctly classified 62 of 92 recurrent patients and 87 of 172 nonrecurrent patients in the EV Set (sensitivity, 0.67; specificity, 0.51). “High-risk” patients had a greater probability of 36-month recurrence (42%) than “low-risk” patients (26%; hazard ratio, 1.80; 95% confidence interval, 1.19-2.71; P = .007; Cox regression) independent of T-classification, the number of lymph nodes examined, histologic grade/subtype, anatomic location, age, sex, or race. The rule outperformed (P = .021) current National Comprehensive Cancer Network Guidelines (hazard ratio, 0.897). The same rule also differentiated the risk of recurrence (hazard ratio, 1.63; P = .031) in a subset of patients from the EV Set who had stage I/II colon cancer only (n = 251). CONCLUSIONS: To the authors' knowledge, the 5-gene rule (OncoDefender-CRC) is the first molecular prognostic that has been validated in both stage I CRC and stage II colon cancer. It outperforms standard clinicopathologic prognostic criteria and obviates the need to retrieve ≥12 lymph nodes for accurate prognostication. It identifies those patients most likely to develop recurrent disease within 3 years after curative surgery and, thus, those most likely to benefit from adjuvant treatment. Cancer 2012. © 2012 American Cancer Society.