Metachronous cancer development in patients with sporadic colorectal adenomas-multivariate risk model with independent and combined value of hTERT and survivin

Overcoming Irinotecan Resistance by Targeting Its Downstream Signaling Pathways in Colon Cancer

Among the most popular chemotherapeutic agents, irinotecan, regarded as a prodrug belonging to the camptothecin family that inhibits topoisomerase I, is widely used to treat metastatic colorectal cancer (CRC). Although immunotherapy is promising for several cancer types, only microsatellite-instable (~7%) and not microsatellite-stable CRCs are responsive to it. Therefore, it is important to investigate the mechanism of irinotecan function to identify cellular proteins and/or pathways that could be targeted for combination therapy. Here, we have determined the effect of irinotecan treatment on the expression/activation of tumor suppressor genes (including p15Ink4b, p21Cip1, p27Kip1, and p53) and oncogenes (including OPN, IL8, PD-L1, NF-κB, ISG15, Cyclin D1, and c-Myc) using qRT-PCR, Western blotting, immunofluorescence (IF), and RNA sequencing of tumor specimens. We employed stable knockdown, neutralizing antibodies (Abs), and inhibitors of OPN, p53, and NF-κB to establish downstream signaling and sensitivity/resistance to the cytotoxic activities of irinotecan. Suppression of secretory OPN and NF-κB sensitized colon cancer cells to irinotecan. p53 inhibition or knockdown was not sufficient to block or potentiate SN38-regulated signaling, suggesting p53-independent effects. Irinotecan treatment inhibited tumor growth in syngeneic mice. Analyses of allograft tumors from irinotecan-treated mice validated the cell culture results. RNA-seq data suggested that irinotecan-mediated activation of NF-κB signaling modulated immune and inflammatory genes in mice, which may compromise drug efficacy and promote resistance. In sum, these results suggest that, for CRCs, targeting OPN, NF-κB, PD-L1, and/or ISG15 signaling may provide a potential strategy to overcome resistance to irinotecan-based chemotherapy.

Mitotic and apoptotic activity in colorectal neoplasia

Background

Colorectal cancer (CRC) is third most commonly diagnosed cancer worldwide. The aim of the prospective study was to evaluate mitosis and apoptosis of epithelial cells at each stage of colorectal neoplasia.

Methods

A total of 61 persons were enrolled into the study: 18 patients with non-advanced colorectal adenoma (non-a-A), 13 patients with advanced colorectal adenoma (a-A), 13 patients with CRC and 17 controls: individuals with normal findings on colonoscopy. Biopsy samples were taken from pathology (patients) and healthy mucosa (patients and healthy controls). Samples were formalin-fixed paraffin-embedded and stained with haematoxylin-eosin. Mitotic and apoptotic activity were evaluated in lower and upper part of the crypts and in the superficial compartment. Apoptotic activity was also assessed using detection of activated caspase-3.

Results

In controls, mitotic activity was present in lower part of crypts, accompanied with low apoptotic activity. Mitotic and apoptotic activity decreased (to almost zero) in upper part of crypts. In superficial compartment, increase in apoptotic activity was observed. Transformation of healthy mucosa into non-a-A was associated with significant increase of mitotic activity in lower and upper part of the crypts and with significant increase of apoptotic activity in all three compartments; p < 0.05. Transformation of non-a-A into a-A did not lead to any further significant increase in apoptotic activity, but was related to significant increase in mitotic activity in upper part of crypts and superficial compartment. A significant decrease in apoptotic activity was detected in all three comparments of CRC samples compared to a-A; p < 0.05. No differences in mitotic and apoptotic activity between biopsies in healthy controls and biopsy samples from healthy mucosa in patients with colorectal neoplasia were observed. Detection of activated caspase-3 confirmed the above findings in apoptotic activity.

Conclusions

Significant dysregulation of mitosis and apoptosis during the progression of colorectal neoplasia, corresponding with histology, was confirmed. In patients with sporadic colorectal neoplasia, healthy mucosa does not display different mitotic and apoptotic activity compared to mucosa in healthy controls and therefore adequate endoscopic/surgical removal of colorectal neoplasia is sufficient.

Risk factors for metachronous colorectal cancer or polyp: A systematic review and meta-analysis

BACKGROUND AND AIM

We conducted a systematic review and meta-analysis to identify personal, lifestyle, and tumor-related risk factors for metachronous colorectal cancer (CRC) and polyp.

METHODS

Relevant studies were identified by searching MEDLINE, Web of Science and Cochrane Central Register through 15 May 2016. Estimates for associations were summarized using random effects models.

RESULTS

Fifty-five studies were included in the review. For individuals who had a CRC resection, having a synchronous polyp was a risk factor for metachronous CRC or polyp (relative risk [RR], 2.04; 95% confidence interval [CI], 1.48-2.82) and having a synchronous CRC (RR, 1.90; 95% CI, 1.25-2.91) and proximally located CRC (RR, 2.12; 95% CI, 1.24-3.64) were risk factors for metachronous CRC. For individuals who had a polypectomy, larger size (RR, 4.26; 95% CI, 2.11-8.57) or severe dysplasia of the initial polyp (RR, 5.15; 95% CI, 2.02-13.14), and having a synchronous polyp (RR, 2.52; 95% CI, 1.35-4.73) were risk factors for metachronous CRC; and a family history of CRC (RR, 1.90; 95% CI, 1.26-2.87), having a synchronous polyp (RR, 2.47; 95% CI, 1.74-3.50) and a larger size (RR, 1.49; 95% CI, 1.03-2.15) and proximal location of the initial polyp (RR, 1.20; 95% CI, 1.02-1.40) were risk factors for metachronous polyp. Meta-regression showed duration of follow-up was not a source of heterogeneity for most associations. There was no evidence that lifestyle factors were associated with metachronous CRC or polyp risk.

CONCLUSION

A comprehensive list of risk factors identified for metachronous CRC or polyp may have important clinical implications.

Tumor size is an independent risk predictor for metachronous colorectal cancer

Non-hereditary colorectal cancer (CRC) patients are at higher risk of developing independent metachronous CRC than cancer-naïve individuals, but the reason is unknown. We studied metachronous CRC risk factors among one thousand five Japanese CRC patients who underwent surgery for CRC. Relative hazard risk of clinical and pathological features was assessed by univariate and multivariate Cox's proportional hazard regression analysis. Observed metachronous CRC incidence was also compared with the expected cancer incidence of the general population in Japan. Twenty-seven metachronous CRCs developed in 24 patients (2.4%) during a follow-up period of 3,676 person-years. Multivariate analysis revealed two factors associated with a high metachronous CRC risk: synchronous CRC (HR = 6.13; p = 1.3x10(-4)) and tumor size ≥ 6.5 cm (HR = 4.34; p = 1x10(-3)). Patients with either synchronous or large solitary tumors exhibited a higher risk for metachronous CRC than patients with solitary small tumors (HR = 7.3; p = 4.3x10(-6)) and that the general Japanese population (SIR = 7.01; p = 3.5x10(-9)), while patients with solitary small tumors did not (SIR = 1.07; p = 0.8). If patients younger than 60 years were excluded, the observations remained unchanged, with tumor size becoming stronger predictor (HR = 5.67; p = 1.7x10(-4)) than the presence of synchronous CRC (HR = 5.34; p = 9.6x10(-4)). Our novel finding that primary tumor size is a strong independent risk factor for metachronous CRC increases the sensitivity of prediction more than twice the presence of synchronous CRC. Our data provides new insights to assess the risk for metachronous lesions that should improve the surveillance regimen for CRC.

Molecular markers of carcinogenesis for risk stratification of individuals with colorectal polyps: a case-control study

Risk stratification using number, size, and histology of colorectal adenomas is currently suboptimal for identifying patients at increased risk for future colorectal cancer. We hypothesized that molecular markers of carcinogenesis in adenomas, measured via immunohistochemistry, may help identify high-risk patients. To test this hypothesis, we conducted a retrospective, 1:1 matched case-control study (n = 216; 46% female) in which cases were patients with colorectal cancer and synchronous adenoma and controls were patients with adenoma but no colorectal cancer at baseline or within 5 years of follow-up. In phase I of analyses, we compared expression of molecular markers of carcinogenesis in case and control adenomas, blind to case status. In phase II of analyses, patients were randomly divided into independent training and validation groups to develop a model for predicting case status. We found that seven markers [p53, p21, Cox-2, β-catenin (BCAT), DNA-dependent protein kinase (DNApkcs), survivin, and O6-methylguanine-DNA methyltransferase (MGMT)] were significantly associated with case status on unadjusted analyses, as well as analyses adjusted for age and advanced adenoma status (P < 0.01 for at least one marker component). When applied to the validation set, a predictive model using these seven markers showed substantial accuracy for identifying cases [area under the receiver operation characteristic curve (AUC), 0.83; 95% confidence interval (CI), 0.74-0.92]. A parsimonious model using three markers performed similarly to the seven-marker model (AUC, 0.84). In summary, we found that molecular markers of carcinogenesis distinguished adenomas from patients with and without colorectal cancer. Furthermore, we speculate that prospective studies using molecular markers to identify individuals with polyps at risk for future neoplasia are warranted.

A highly sensitive telomerase activity assay that eliminates false-negative results caused by PCR inhibitors

An assay for telomerase activity based on asymmetric polymerase chain reaction (A-PCR) on magnetic beads (MBs) and subsequent application of cycling probe technology (CPT) is described. In this assay, the telomerase reaction products are immobilized on MBs, which are then washed to remove PCR inhibitors that are commonly found in clinical samples. The guanine-rich sequences (5'-(TTAGGG)n-3') of the telomerase reaction products are then preferentially amplified by A-PCR, and the amplified products are subsequently detected via CPT, where a probe RNA with a fluorophore at the 5' end and a quencher at the 3' end is hydrolyzed by RNase H in the presence of the target DNA. The catalyst-mediated cleavage of the probe RNA enhances fluorescence from the 5' end of the probe. The assay allowed us to successfully detect HeLa cells selectively over normal human dermal fibroblast (NHDF) cells. Importantly, this selectivity produced identical results with regard to detection of HeLa cells in the absence and presence of excess NHDF cells; therefore, this assay can be used for practical clinical applications. The lower limit of detection for HeLa cells was 50 cells, which is lower than that achieved with a conventional telomeric repeat amplification protocol assay. Our assay also eliminated false-negative results caused by PCR inhibitors. Furthermore, we show that this assay is appropriate for screening among G-quadruplex ligands to find those that inhibit telomerase activity.

TERT's role in colorectal carcinogenesis

Telomerase reverse transcriptase (TERT) is one of the main functional subunits of the telomerase enzyme, which functions to increase telomere length. Studies have suggested that TERT may be important to the etiology of colorectal cancer. In this study we evaluate seven TERT SNPs in 1555 incident colon cancer cases and 1956 matched controls and in 754 incident rectal cancer cases and 959 matched controls. We observed that two TERT SNPs were associated with colon cancer. TERT rs2736118 was associated with increased risk of colon cancer (OR = 1.31, 95% CI 1.02, 1.69) and TERT-CLPTM1L rs2853668 was inversely associated with colon cancer (OR = 0.71, 95% CI 0.55, 0.92). TERT-CLPTM1L rs2853668 also was inversely associated with rectal cancer (OR 0.62, 95% CI 0.43, 0.90). BMI interacted significantly with three TERT SNPs to alter risk of colon cancer. Those with the variant allele and who were obese had the greatest risk of colon cancer. TERT-CLPTM1L rs2853668 interacted significantly with aspirin/NSAID use, where those with the AA genotype had a much lower risk of colon cancer when using aspirin/NSAIDs than those with the other genotypes. Several TERT SNPs were uniquely associated with CIMP+ and MSI tumors. These data confirm earlier reports of the association between TERT-CLPTM1L and colon and rectal cancer. Our detection of a significant interaction with BMI for multiple TERT SNPs and unique associations with CIMP+ tumors enhance our understanding of TERT's role in colon carcinogenesis.

Colorectal Chemoprevention Pilot Study (SWOG-9041), randomized and placebo controlled: the importance of multiple luminal lesions

BACKGROUND

Colorectal cancer is common worldwide and chemoprevention has the potential of reducing the number of individuals who may suffer and perish from this disease.

METHODS

A randomized placebo controlled pilot study in colorectal cancer patients was performed using calcium carbonate as the test agent in a multi-institutional oncology study group.

RESULTS

Two hundred twenty volunteers were randomized in the study. The primary goals of compliance, accrual, and toxicity monitoring are presented. Presence of multiple adenomas at study entry and subsequent development of metachronous adenomas were recorded and found to be associated with synchronous adenomas. The secondary endpoint of recurrent adenomas indicated lower rates of new adenoma in the volunteers randomized to the calcium group.

CONCLUSION

This pilot study indicates the feasibility of enrolling survivors of colorectal cancer as study volunteers in a colorectal neoplasm chemoprevention clinical trial and oral calcium continues to be a potentially effective drug in reducing colorectal adenomas.

Expression of the antiapoptotic protein survivin in colon cancer

BACKGROUND

The antiapoptotic protein survivin has been demonstrated to play an important role in colorectal carcinogenesis. However it is unclear whether the upregulation of survivin is maintained through progressive stages of disease, or if other apoptosis-related genes are coexpressed and/or repressed. We sought to evaluate survivin expression in colonic neoplasia and identify relationships with additional regulators of apoptosis.

PATIENTS AND METHODS

Tissue samples from 168 patients with primary colorectal cancer were profiled using the GeneChip Human Genome U133 Plus 2.0 Array (Affymetrix, Santa Clara, CA) and evaluated for survivin expression. Immunohistochemical staining for survivin and a panel of apoptosis-associated proteins were used in 86 patients with tissue microarray (TMA) blocks; scoring was by stain intensity and percentage of positive cells (range, 0-9).

RESULTS

Survivin mRNA was upregulated (1.8-fold increase) in primary colon cancers- irrespective of American Joint Committee on Cancer (AJCC) stage- and metastases compared with normal colonic tissue (P < .0001). Survivin staining was positive in 93% of adenocarcinomas (median immunohistochemistry [IHC] score: 2 [range, 1-6]), 100% of adenomas (1 [range,1-2]), and 43% of normal colonic mucosa (1, [range 1-2]) (P = .006). Survivin expression increased with worsening tumor grade (P < .05). In colon cancers, survivin expression positively correlated with the coexpression of PUMA (P < .001), TACE (P = .003), and MCL1 (P = .01), and trended toward an inverse correlation with BAX (P = .058).

CONCLUSIONS

Survivin expression increases during the normal mucosa-adenoma-carcinoma sequence and is maintained throughout progression of disease, which strengthens its appeal as a therapeutic target. Furthermore, we have demonstrated co-overexpression of several other apoptosis-related genes, which may in turn serve as additional and potentially synergistic therapeutic targets.

Diagnostic accuracy and receiver-operating characteristics curve analysis in surgical research and decision making

In surgical research, the ability to correctly classify one type of condition or specific outcome from another is of great importance for variables influencing clinical decision making. Receiver-operating characteristic (ROC) curve analysis is a useful tool in assessing the diagnostic accuracy of any variable with a continuous spectrum of results. In order to rule a disease state in or out with a given test, the test results are usually binary, with arbitrarily chosen cut-offs for defining disease versus health, or for grading of disease severity. In the postgenomic era, the translation from bench-to-bedside of biomarkers in various tissues and body fluids requires appropriate tools for analysis. In contrast to predetermining a cut-off value to define disease, the advantages of applying ROC analysis include the ability to test diagnostic accuracy across the entire range of variable scores and test outcomes. In addition, ROC analysis can easily examine visual and statistical comparisons across tests or scores. ROC is also favored because it is thought to be independent from the prevalence of the condition under investigation. ROC analysis is used in various surgical settings and across disciplines, including cancer research, biomarker assessment, imaging evaluation, and assessment of risk scores.With appropriate use, ROC curves may help identify the most appropriate cutoff value for clinical and surgical decision making and avoid confounding effects seen with subjective ratings. ROC curve results should always be put in perspective, because a good classifier does not guarantee the expected clinical outcome. In this review, we discuss the fundamental roles, suggested presentation, potential biases, and interpretation of ROC analysis in surgical research.

Inhibitor of apoptosis protein family as diagnostic markers and therapeutic targets of colorectal cancer

The apoptosis and antiapoptotic signaling pathways are important for regulating carcinogenesis and cancer progression, and for determining prognosis. Molecules involved in apoptosis represent potential cancer diagnostic markers and therapeutic targets. The inhibitor of apoptosis protein (IAP) family includes several important molecules involved in apoptosis that might represent such targets. Increasing evidence has demonstrated that the IAP family of proteins is integral for antiapoptotic and nuclear factor-κB signal transduction, and enhanced expression of IAPs contributes to colon carcinogenesis and its poor prognosis, as well as to drug resistance of tumors. X-linked IAP, cIAP1, cIAP2, and survivin are prognostic markers of colorectal cancer, and survivin and cIAP2 are also utilized to predict the effect of anticancer treatment in colorectal cancer patients. Novel therapies such as YM155 and LY2181308 targeting survivin, AEG35156 and phenoxodiol targeting X-linked IAP, AT-406 as a Smac mimetic, and survivin peptides are currently being evaluated in clinical trials. This report reviews the involvement of the IAP family in colorectal adenocarcinoma in order to summarize the role of the IAP family members as diagnostic and therapeutic targets, and to provide an overview of the future course of research in this area.

PPARgamma ligands inhibit telomerase activity and hTERT expression through modulation of the Myc/Mad/Max network in colon cancer cells

In human cells the length of telomeres depends on telomerase activity. This activity and the expression of the catalytic subunit of human telomerase reverse transcriptase (hTERT) is strongly up-regulated in most human cancers. hTERT expression is regulated by different transcription factors, such as c-Myc, Mad1 and Sp1. In this study, we demonstrated that 15d-PG J2 and rosiglitazone (an endogenous and synthetic peroxisome proliferators activated receptor γ (PPARγ) ligand, respectively) inhibited hTERT expression and telomerase activity in CaCo-2 colon cancer cells. Moreover, both ligands inhibited c-Myc protein expression and its E-box DNA binding activity. Additionally, Mad1 protein expression and its E-box DNA binding activity were strongly increased by 15d-PG J2 and, to a lesser extent, by rosiglitazone. Sp1 transcription factor expression and its GC-box DNA binding activity were not affected by both PPARγ ligands. Results obtained by transient transfection of CaCo-2 cells with pmaxFP-Green-PRL plasmid constructs containing the functional hTERT core promoter (including one E-box and five GC-boxes) and its E-box deleted sequences, cloned upstream of the green fluorescent protein reporter gene, demonstrated that 15d-PG J2, and with minor effectiveness, rosiglitazone, strongly reduced hTERT core promoter activity. E-boxes for Myc/Mad/Max binding showed a higher activity than GC-boxes for Sp1. By using GW9662, an antagonist of PPARγ, we demonstrated that the effects of 15d-PG J2 are completely PPARγ independent, whereas the effects of rosiglitazone on hTERT expression seem to be partially PPARγ independent. The regulation of hTERT expression by 15d-PG J2 and rosiglitazone, through the modulation of the Myc/Max/Mad1 network, may represent a new mechanism of action of these substances in inhibiting cell proliferation.

Characteristics of metachronous colorectal adenomas found during long-term follow-up: analysis of four subsequent generations of adenoma recurrence

OBJECTIVE

Because of the high recurrence rates of colorectal adenomas, regular surveillance by colonoscopy has been recommended, but there is still a dearth of information on the long-term results of follow-up colonoscopy after polypectomy. The aims of this study were to determine the differences between initial adenomas and metachronous lesions, to evaluate the effect of long-term surveillance and to describe the hypothetical origin of the colorectal adenoma-carcinoma sequence.

MATERIAL AND METHODS

Between 1978 and 2003 a total of 1091 patients undergoing periodic surveillance examinations were prospectively documented at the Erlangen Registry of Colorectal Polyps. Differences between initial and metachronous lesions found during long-term follow-up were studied. Statistical analysis using chi(2) testing of adenoma characteristics found in four subsequent recurrence periods was carried out, and the relative risk (RR) for the development of metachronous adenomas of advanced pathology was calculated.

RESULTS

In comparison with the initial findings, metachronous adenomas are generally significantly smaller lesions (p<0.00001), usually tubular in shape (p<0.00001) and bearing high-grade dysplasia less often (p<0.00001) and are usually located in the right colon (p<0.00001). These differences are found between the initial and four subsequent generations of metachronous adenomas. The number of synchronous adenomas is reduced only in the first recurrence (p<0.001); in the further generations equal proportions of multiplicity are found, as in the baseline examination. Patients with adenomas of advanced pathology, i.e. large, tubulovillous or villous adenomas at baseline, have a significantly higher risk for large (RR 2.73; 95% CI 1.77-4.20), tubulovillous or villous (RR 1.55; 95% CI 1.06-2.25) or multiple (RR 2.45; 95% CI 1.83-3.29) metachronous adenomas at the first recurrence.

CONCLUSIONS

Metachronous adenomas show the uniform characteristics of being small tubular lesions rarely bearing high-grade dysplasia, usually located in the right colon. Thus regular follow-up colonoscopy can provide sufficient colorectal carcinoma prevention.

Endoscopy, morphology, morphometry and molecular markers: predicting cancer risk in colorectal adenoma

The evaluation of short- and long-term risk for developing cancer in patients with colorectal adenomas is controversial. Good, reliable predictors of cancer risk in any adenoma are currently lacking and are limited to adenoma size, number and histologic type. In fact, the evaluation of any adenoma or precancer lesion (e.g., hyperplastic polyps, serrated adenoma or aberrant crypt foci) within the colorectum may be assessed by a number of techniques ranging from direct visualization through the endoscope, to microscopic assessment, and to evaluation at the molecular level. Emerging techniques may yield improved methods of adenoma risk-assessment in the near future. For one, newer endoscopy technologies include chromoendoscopy or endocytoscopy, which now render endoscopists able to resolve the surface and subsurface mucosa at cellular resolution in vivo and in real time - thus, bringing the microscope to the patient's bedside. This new era in endoscopic imaging is dubbed 'histoendoscopy'. Further, while traditional views of classifying protruding and sessile lesions include those of Haggitt, the sm-classification, the Japanese and the so-called Vienna classifications to evaluate neoplasia, the development of new molecular techniques may give way to new methods of classifying preneoplasia and precancerous lesions. This review discusses some pros and cons of risk evaluation technologies in the colorectal tract by endoscopy, microscopy, and quantitative and molecular features. The morphometry-based studies performed over the past decades for the quantitative assessment of cellular and nuclear features within adenomas have failed to yield results amenable for clinical translation and are unlikely to improve further and gain widespread use with current technology. Rather, emerging knowledge of pathway-specific markers through the outlining of a molecular classification will likely be the basis for improved detection and diagnosis. The emerging genomic and proteomic technologies allowing for noninvasive tests to detect (asymptomatic) cancer and neoplasia are discussed. Lastly, the importance of recognizing bias and pitfalls and the adherence to guidelines for biomarker research are addressed.