Accumulated clonal genetic alterations in familial and sporadic colorectal carcinomas with widespread instability in microsatellite sequences

Microsatellite Instability in Sporadic Colorectal Malignancy: A Pilot Study from Northern India

BACKGROUND

Three molecular pathways are described as the genetic basis of colorectal tumorigenesis. Among these, microsatellite instability (MSI) has shown greatest promise in serving as a biomarker to determine disease aggression by tumour biology, recurrence, and response to chemotherapy.

METHODOLOGY

This prospective observational pilot study included patients of colorectal cancers, in a population subset coming to a tertiary care hospital in northern India, who were operated with curative or palliative intent over a period of one year and followed up for a maximum of 55 months. The post-operative pathological assessment was done for MSI status using PCR technique, and an attempt was made to evaluate its correlation with conventional clinical and histological parameters, early recurrences, disease-free survival and overall survival in comparison to MSS type tumours in sporadic cases of colorectal malignancies.

RESULTS

Out of 38 patients of colorectal cancer, 26 were included in the study. Male to female ratio was 7:6 (n=14:12). Mean age of presentation was 48±14.2 years. Incidence of MSI was n=4 (15.4%). On subgroup analysis, age of presentation (p=0.044) and evidence of perineural invasion (p=0.017) was found to have significant statistical association with MSI tumour biology. Recurrence was seen in seven of the seventeen patients who previously had no synchronous or metastatic disease (41.2%). The mean disease-free survival for MSS was 21.32 months and was 25.25 months for MSI group which was statistically insignificant (p = 0.277). Out of four MSI tumour biology patients one was alive and without recurrence at 47 months. While the other two were alive and without recurrence till 27 months of follow-up.   Conclusion: Age and perineural invasion showed statistically significant association with MSI tumour biology. Due to the small sample size statistical significance was not established with site, recurrence rate, DFS and OS.

A Case of Muir-Torre Syndrome

Muir-Torre syndrome (MTS) is an autosomal dominant condition characterized by dermatological tumors along with visceral malignancies. The dermatological manifestations include recurrent sebaceous adenomas and keratoacanthomas. The commonly seen visceral malignancies are colorectal, gynecological, and urological. It is a variant of hereditary non-polyposis colorectal carcinoma syndrome (HNPCC). The underlying genetic mechanism is germline mutations in the DNA mismatch repair (MMR) genes leading to microsatellite instability (MSI), conferring an increased risk of developing malignancies. This is a case of a 57-year-old male patient with a history of colon cancer diagnosed at age 32 and multiple sebaceous adenomas. The patient also has a strong family history of cancer. They were referred to oncology after the immunohistochemical staining of a sebaceous adenoma showed loss of expression for MSH2 and MSH6. Next-generation sequencing identified a mutation in the MSH2 gene. These patients require genetic testing, counseling, and close follow-up with regular screening for cancer.

Microsatellite Instability (MSI) as an Independent Predictor of Pathologic Complete Response (PCR) in Locally Advanced Rectal Cancer: A National Cancer Database (NCDB) Analysis

OBJECTIVE

The relationship between microsatellite instability (MSI) and response to neoadjuvant chemoradiation in rectal cancer is not well understood.

BACKGROUND

We utilized the National Cancer Database (NCDB) to investigate the association between MSI and pathologic complete response (pCR) in this patient population.

METHODS

We analyzed 5086 patients between 2010 and 2015 with locally advanced rectal cancer who were tested for MSI and treated definitively with chemoradiation followed by surgery. Primary comparison groups were between 4450 MSI-negative(-) and 636 MSI-positive(+) patients. Multivariable regression analysis was conducted to identify demographic, therapeutic, and clinical characteristics predictive of pCR. Cox proportional-hazard ratios were used for survival.

RESULTS

All patients were treated with definitive chemoradiation (median dose 50.4 Gy) followed by resection within 4 months. MSI(+) patients were associated with earlier year of diagnosis and higher-grade tumors (P < 0.05).The overall pCR rate was 8.6%, including 8.9% for MSI(-) and 5.9% for MSI(+) tumors (P = 0.01). Along with lower T stage, MSI(+) cases were significantly associated with a reduced pCR rate (odds ratio 0.65, 95% confidence interval 0.43-0.96) with multivariable analysis. The 5-year survival for patients with pCR was 93% compared with 73% without it (<0.001).

CONCLUSION

Microsatellite instability was independently associated with a reduction in pCR for locally advanced rectal cancer after neoadjuvant chemoradiation in this NCDB-based analysis.

Microsatellite instability and response to neoadjuvant chemoradiotherapy in rectal cancer: A systematic review and meta-analysis

BACKGROUND

Response to neoadjuvant chemoradiotherapy (CRT) in locally advanced rectal cancer is variable. Identification of biomarkers to predict response is desirable in order to provide prognostic information and targeted therapy. Several studies have investigated microsatellite instability (MSI) as a predictor of response to CRT with contradictory results. This study aims to clarify the effect of MSI status on response to CRT in locally advanced rectal cancer through systematic review and meta-analysis.

METHODS

A systematic search of PubMed, Embase and Cochrane databases was performed for all studies relating to MSI and response to CRT in rectal cancer using the search algorithm (Microsatellite Instability) AND (Chemoradiotherapy) AND (Rectal Cancer). From each included study the number of patients with MSI tumors and Microsatellite Stable (MSS) tumors and the numbers achieving pathological complete response (pCR) were recorded. Pooled outcome measures were determined using a random effects model and the odds ratio estimated with variance and 95% confidence interval.

RESULTS

Nine published studies were identified reporting data on MSI and its effect on outcome after CRT for locally advanced rectal cancer. Five studies describing 5,877 patients included data on MSI and the number of patients achieving pCR. There was no significant association between MSI and pCR (MSI Vs MSS: 10.1% Vs 6.6%, OR 1.38, 95% CI: 0.7-2.72, p = 0.35).

CONCLUSION

This meta-analysis concludes that there appears to be no significant difference in pCR rate following CRT in patients with MSI versus MSS rectal tumors.

Microsatellite Instability (MSI) as an Independent Predictor of Pathologic Complete Response (PCR) in Locally Advanced Rectal Cancer: A National Cancer Database (NCDB) Analysis

OBJECTIVE

The relationship between microsatellite instability (MSI) and response to neoadjuvant chemoradiation in rectal cancer is not well understood.

BACKGROUND

We utilized the National Cancer Database (NCDB) to investigate the association between MSI and pathologic complete response (pCR) in this patient population.

METHODS

We analyzed 5086 patients between 2010 and 2015 with locally advanced rectal cancer who were tested for MSI and treated definitively with chemoradiation followed by surgery. Primary comparison groups were between 4450 MSI-negative(-) and 636 MSI-positive(+) patients. Multivariable regression analysis was conducted to identify demographic, therapeutic, and clinical characteristics predictive of pCR. Cox proportional-hazard ratios were used for survival.

RESULTS

All patients were treated with definitive chemoradiation (median dose 50.4 Gy) followed by resection within 4 months. MSI(+) patients were associated with earlier year of diagnosis and higher-grade tumors (P < 0.05).The overall pCR rate was 8.6%, including 8.9% for MSI(-) and 5.9% for MSI(+) tumors (P = 0.01). Along with lower T stage, MSI(+) cases were significantly associated with a reduced pCR rate (odds ratio 0.65, 95% confidence interval 0.43-0.96) with multivariable analysis. The 5-year survival for patients with pCR was 93% compared with 73% without it (<0.001).

CONCLUSION

Microsatellite instability was independently associated with a reduction in pCR for locally advanced rectal cancer after neoadjuvant chemoradiation in this NCDB-based analysis.

Microsatellite instability detection using a large next-generation sequencing cancer panel across diverse tumour types

Aim

Microsatellite instability (MSI), a hallmark of DNA mismatch repair deficiency, is a key molecular biomarker with multiple clinical implications including the selection of patients for immunotherapy, identifying patients who may have Lynch syndrome and predicting prognosis in patients with colorectal tumours. Next-generation sequencing (NGS) provides the opportunity to interrogate large numbers of microsatellite loci concurrently with genomic variants. We sought to develop a method to detect MSI that would not require paired normal tissue and would leverage the sequence data obtained from a broad range of tumours tested using our 467-gene NGS Columbia Combined Cancer Panel (CCCP).

Methods

Altered mononucleotide and dinucleotide microsatellite loci across the CCCP region of interest were evaluated in clinical samples encompassing a diverse range of tumour types. The number of altered loci was used to develop a decision tree classifier model trained on the retrospectively collected cohort of 107 clinical cases sequenced by the CCCP assay.

Results

The classifier was able to correctly classify all cases and was then used to analyse a test set of clinical cases (n=112) and was able to correctly predict their MSI status with 100% sensitivity and specificity. Analysis of recurrently altered loci identified alterations in genes involved in DNA repair, signalling and transcriptional regulation pathways, many of which have been implicated in MSI tumours.

Conclusion

This study highlights the utility of this approach, which should be applicable to laboratories performing similar testing.

Sessile Serrated Adenomas: How to Detect, Characterize and Resect

Serrated polyps are important contributors to the burden of colorectal cancers (CRC). These lesions were once considered to have no malignant potential, but currently up to 30% of all CRC are recognized to arise from the serrated neoplasia pathway. The primary premalignant lesions are sessile serrated adenomas/polyps (SSA/Ps), although traditional serrated adenomas are relatively uncommon. Compared to conventional adenomas, SSA/Ps are morphologically subtle with indistinct borders, may be difficult to detect endoscopically, are more prevalent than previously thought, are associated with synchronous and metachronous advanced neoplasia, and have a higher risk of incomplete resection. Although many lesions remain “dormant,” progressive disease is associated with the development of dysplasia and more rapid progression to CRC. As a result, SSA/Ps are strongly implicated in the development of interval cancers. These factors represent unique challenges that require a meticulous approach to their management. In this review, we summarize the contemporary literature on the characterization, detection and resection of SSA/Ps.

Mismatch repair deficient hematopoietic stem cells are preleukemic stem cells

Whereas transformation events in hematopoietic malignancies may occur at different developmental stages, the initial mutation originates in hematopoietic stem cells (HSCs), creating a preleukemic stem cell (PLSC). Subsequent mutations at either stem cell or progenitor cell levels transform the PLSC into lymphoma/leukemia initiating cells (LIC). Thymic lymphomas have been thought to develop from developing thymocytes. T cell progenitors are generated from HSCs in the bone marrow (BM), but maturation and proliferation of T cells as well as T-lymphomagenesis depends on both regulatory mechanisms and microenvironment within the thymus. We studied PLSC linked to thymic lymphomas. In this study, we use MSH2-/- mice as a model to investigate the existence of PLSC and the evolution of PLSC to LIC. Following BM transplantation, we found that MSH2-/- BM cells from young mice are able to fully reconstitute multiple hematopoietic lineages of lethally irradiated wild-type recipients. However, all recipients developed thymic lymphomas within three and four months post transplantation. Transplantation of different fractions of BM cells or thymocytes from young health MSH2-/- mice showed that an HSC enriched fraction always reconstituted hematopoiesis followed by lymphoma development. In addition, lymphomas did not occur in thymectomized recipients of MSH2-/- BM. These results suggest that HSCs with DNA repair defects such as MSH2-/- are PLSCs because they retain hematopoietic function, but also carry an obligate lymphomagenic potential within their T-cell progeny that is dependent on the thymic microenvironment.

Obesity and colorectal cancer: molecular features of adipose tissue

The huge part of population in developed countries is overweight or obese. Obesity is often determined by body mass index (BMI) but new accurate methods and ratios have recently appeared to measure body fat or fat located in the intestines. Early diagnosis of obesity is crucial since it is considered an increasing colorectal cancer risk factor. On the one hand, colorectal cancer has been strongly associated with lifestyle factors. A diet rich in red and processed meats may increase colorectal cancer risk; however, high-fiber diets (grains, cereals and fruits) have been associated with a decreased risk of colorectal cancer. Other life-style factors associated with obesity that also increase colorectal cancer risk are physical inactivity, smoking and high alcohol intake. Cutting-edge studies reported that high-risk transformation ability of adipose tissue is due to production of different pro-inflammatory cytokines like IL-8, IL-6 or IL-2 and other enzymes like lactate dehydrogenase (LDH) and tumour necrosis factor alpha (TNFα). Furthermore, oxidative stress produces fatty-acid peroxidation whose metabolites possess very high toxicities and mutagenic properties. 4-hydroxy-2-nonenal (4-HNE) is an active compounds that upregulates prostaglandin E2 which is directly associated with high proliferative colorectal cancer. Moreover, 4-HNE deregulates cell proliferation, cell survival, differentiation, autophagy, senescence, apoptosis and necrosis via mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PIK3CA)—AKT and protein kinase C pathways. Other product of lipid peroxidation is malondialdehyde (MDA) being able to regulate insulin through WNT-pathway as well as having demonstrated its mutagenic capability. Accumulation of point mutation enables genomic evolution of colorectal cancer described in the model of Fearon and Vogelstein. In this review, we will summarize different determination methods and techniques to assess a truthfully diagnosis and we will explain some of the capabilities that performs adipocytes as the largest endocrine organ.

Target gene mutational pattern in Lynch syndrome colorectal carcinomas according to tumour location and germline mutation

BACKGROUND

We previously reported that the target genes in sporadic mismatch repair (MMR)-deficient colorectal carcinomas (CRCs) in the distal colon differ from those occurring elsewhere in the colon. This study aimed to compare the target gene mutational pattern in microsatellite instability (MSI) CRC from Lynch syndrome patients stratified by tumour location and germline mutation, as well as with that of sporadic disease.

METHODS

A series of CRC from Lynch syndrome patients was analysed for MSI in genes predicted to be selective MSI targets and known to be involved in several pathways of colorectal carcinogenesis.

RESULTS

The most frequently mutated genes belong to the TGF-β superfamily pathway, namely ACVR2A and TGFBR2. A significantly higher frequency of target gene mutations was observed in CRC from patients with germline mutations in MLH1 or MSH2 when compared with MSH6. Mutations in microsatellite sequences (A)7 of BMPR2 and (A)8 of MSH3 were significantly more frequent in the distal CRC. Additionally, we observed differences in MSH3 and TGFBR2 mutational frequency between Lynch syndrome and sporadic MSI CRC regarding tumour location.

CONCLUSIONS

Our results indicate that the pattern of genetic changes differs in CRC depending on tumour location and between Lynch syndrome and sporadic MSI CRC, suggesting that carcinogenesis can occur by different pathways even if driven by generalised MSI.

BRAF vs RAS oncogenes: are mutations of the same pathway equal? Differential signalling and therapeutic implications

As the increased knowledge of tumour heterogeneity and genetic alterations progresses, it exemplifies the need for further personalized medicine in modern cancer management. Here, the similarities but also the differential effects of RAS and BRAF oncogenic signalling are examined and further implications in personalized cancer diagnosis and therapy are discussed. Redundant mechanisms mediated by the two oncogenes as well as differential regulation of signalling pathways and gene expression by RAS as compared to BRAF are addressed. The implications of RAS vs BRAF differential functions, in relevant tumour types including colorectal cancer, melanoma, lung cancer are discussed. Current therapeutic findings and future viewpoints concerning the exploitation of RAS-BRAF-pathway alterations for the development of novel therapeutics and efficient rational combinations, as well as companion tests for relevant markers of response will be evaluated. The concept that drug-resistant cells may also display drug dependency, such that altered dosing may prevent the emergence of lethal drug resistance posed a major therapy hindrance.

KRAS mutational status in Japanese patients with colorectal cancer: results from a nationwide, multicenter, cross-sectional study

OBJECTIVE

KRAS gene mutations are a useful predictive factor for the efficacy of anti-epidermal growth factor receptor therapeutics. Since there were no large-scale studies among Asian populations, we designed an observational nationwide study in Japan.

METHODS

Formalin-fixed paraffin-embedded tissue blocks or sections from primary or metastatic lesions were obtained from patients registered between 2009 and 2010 for genomic DNA extraction. KRAS gene was analyzed by direct sequencing or Luminex assay. The primary endpoint was the frequency of KRAS gene mutations and the secondary endpoints were differences in KRAS mutation rates by various stratification factors. Univariate and multivariate analyses were performed to investigate relationships between KRAS mutation rates and patient background factors.

RESULTS

We analyzed 5790 eligible samples out of 5887 registered. The overall KRAS mutation rate was 37.6%, with 29.9% in codon 12 and 7.7% in codon 13, and wild type was 62.4%. A significant relationship with the KRAS mutation rate was found for gender, age, the year that the sample was prepared and the site of the primary lesion.

CONCLUSION

The KRAS mutation rate of Japanese colorectal cancer patients was 37.6%. Gender, age, the site of the primary lesion and the year that the sample was prepared were independent risk factors for KRAS mutations.

A systems approach defining constraints of the genome architecture on lineage selection and evolvability during somatic cancer evolution

Most clinically distinguishable malignant tumors are characterized by specific mutations, specific patterns of chromosomal rearrangements and a predominant mechanism of genetic instability but it remains unsolved whether modifications of cancer genomes can be explained solely by mutations and selection through the cancer microenvironment.

It has been suggested that internal dynamics of genomic modifications as opposed to the external evolutionary forces have a significant and complex impact on Darwinian species evolution. A similar situation can be expected for somatic cancer evolution as molecular key mechanisms encountered in species evolution also constitute prevalent mutation mechanisms in human cancers. This assumption is developed into a systems approach of carcinogenesis which focuses on possible inner constraints of the genome architecture on lineage selection during somatic cancer evolution. The proposed systems approach can be considered an analogy to the concept of evolvability in species evolution.

The principal hypothesis is that permissive or restrictive effects of the genome architecture on lineage selection during somatic cancer evolution exist and have a measurable impact. The systems approach postulates three classes of lineage selection effects of the genome architecture on somatic cancer evolution: i) effects mediated by changes of fitness of cells of cancer lineage, ii) effects mediated by changes of mutation probabilities and iii) effects mediated by changes of gene designation and physical and functional genome redundancy. Physical genome redundancy is the copy number of identical genetic sequences. Functional genome redundancy of a gene or a regulatory element is defined as the number of different genetic elements, regardless of copy number, coding for the same specific biological function within a cancer cell. Complex interactions of the genome architecture on lineage selection may be expected when modifications of the genome architecture have multiple and possibly opposed effects which manifest themselves at disparate times and progression stages.

Dissection of putative mechanisms mediating constraints exerted by the genome architecture on somatic cancer evolution may provide an algorithm for understanding and predicting as well as modifying somatic cancer evolution in individual patients.

Chromosomal instability (CIN) phenotype, CIN high or CIN low, predicts survival for colorectal cancer

PURPOSE

To examine whether chromosomal instability (CIN) phenotype, determined by the severity of CIN, can predict survival for stages II and III colorectal cancer (CRC).

PATIENTS AND METHODS

We determined microsatellite instability (MSI) and loss of heterozygosity (LOH) status in 1,103 patients (training [n = 845] and validation [n = 258] sets with stages II and III CRC). The LOH ratio was defined as the frequency of LOH in chromosomes 2p, 5q, 17p, and 18q. According to the LOH ratio, non-MSI high tumors were classified as CIN high (LOH ratio ≥ 33%) or CIN low (LOH ratio < 33%). CIN-high tumors were subclassified as CIN high (mild type; LOH ratio < 75%) or CIN high (severe type; LOH ratio ≥ 75%). We used microarrays to identify a gene signature that could classify the CIN phenotype and evaluated its ability to predict prognosis.

RESULTS

CIN high showed the worst survival (P < .001), whereas there was no significant difference between CIN low and MSI high. CIN high (severe type) showed poorer survival than CIN high (mild type; P < .001). Multivariate analysis revealed that CIN phenotype was an independent risk factor for disease-free and overall survival, respectively, in both the training (P < .001 and P = .0155) and validation sets (P < .001 and P = .0076). Microarray analysis also revealed that survival was significantly poorer in those with the CIN-high than in the CIN-low gene signature (P = .0203). In a validation of 290 independent CRCs (GSE14333), the CIN-high gene signature showed significantly poorer survival than the CIN-low signature (P = .0047).

CONCLUSION

The CIN phenotype is a predictive marker for survival and may be used to select high-risk patients with stages II and III CRC.

Serrated polyposis syndrome and the role of serrated polyps in colorectal cancer development

SUMMARY Serrated polyposis syndrome is characterized by the presence of multiple colorectal serrated polyps and is associated with an increased colorectal cancer risk. The mixture of distinct precursor lesion types and malignancies in serrated polyposis syndrome provides a unique model to study the recently proposed serrated neoplasia pathway. This pathway involves the progression of serrated polyps, that is, hyperplastic polyps, sessile serrated adenoma/polyps and/or traditional serrated adenomas, to colorectal cancer. The early genetic events of this route, as currently identified, are BRAF or KRAS mutations and an enhanced CPG island methylation status of multiple genes. There is evidence to suggest that a proportion of sporadic colorectal cancers originate from serrated polyps, which encompass molecular sequences of events such as hypermethylation of different genes and BRAF mutations. This review discusses the characteristics and clinical relevance of serrated polyps and provides an overview of the clinical aspects and treatment of serrated polyposis syndrome.

Molecular profile of colorectal cancer in Indonesia: is there another pathway?

Colorectal cancer is an emerging public health problem in Indonesia and currently ranks among the three highest cancers. Lack of a colonoscopy screening and lifestyle changes might contribute to it. In the last few decades, there is an increasing interest towards the contribution of genetic-environment interaction in colorectal carcinogenesis. Some studies have indicated that CRC might develop through several different pathways; the three major routes are chromosomal instability (CIN), microsatellite instability (MSI), and inflammatory pathways. An earlier study on clinical epidemiology of CRC in Indonesia showed that the majority of patients were diagnosed between 45 and 50 years old, with a mean age around 47 years old. Further studies showed that most young Indonesian cases of CRC do not have hereditary characteristics; however, the CRC did not follow the conventional pathways of sporadic CRC (the CIN) pathway. Rather, it is a mixed of MSI and inflammatory pathways. Immunohistochemical studies showed that the proportion of patients with negative mismatch repair proteins was 43.5% for MSH2 and 83.5% for MLH1. Along the sporadic colorectal carcinogenesis pathway, there was a specific role of cyclooxygenase-2 (COX-2) enzyme during the polyp formation. COX-2 expression was reported in about 80% CRC cases worldwide. However, our study found only 49% of COX-2 expression among the CRC patients. Interestingly, an inflammatory marker, the nucleus factor κB (NF-κB), was expressed in about 73.5% cases, in line with a previous study. More recently, KRAS has been used as a potential tumor marker to select treatment and its expression was reported to be as high as 30%-40% worldwide. However, we found that KRAS gene expression was only 16.3%. Our findings support that CRC patients in Indonesian might follow a distinct pathway, a hypothesis that deserves further exploration.

Relation between transforming growth factor-β1 expression, its receptor and clinicopathological factors and survival in HER2-negative gastric cancers

BACKGROUND

Gastric cancer is still the most prevalent neoplasia in many countries. Therefore, besides the clinicopathological factors known to be prognostic markers, new independent parameters are being investigated. This study was to investigate the expression of transforming growth factor - β1 (TGF-β1) and transforming growth factor - β1 receptor II (TGF-β1RII) in HER2/neu negative gastric carcinomas and to explore the correlations, the clinicopathological characteristics and prognosis of gastric carcinoma.

PATIENTS AND METHODS

Surgical specimens from 42 patients with gastric cancer were examined for the presence of HER2/neu, TGF-β1 and TGF-β1RII by immunohistochemistry. The correlation between expression of the proteins and patient clinicopathological parameters was evaluated and the prognostic significance of TGF-β1 and of receptor expression was assessed.

RESULTS

All specimens demonstrated HER2/neu-negative status. TGF-β1 analyses exhibited predominantly cytoplasmic and membranous immunostaining. We found that 80% of intestinal gastric cancer specimens have TGF-β1 expression, while in the diffuse type they are 43%. Also the tumors with low and moderate differentiation were positive for TGF-βRII (p = 0.041). Finally we found that median survival period of the patients was 37.03 months and the patients with TGF-β1 expression had worse prognosis after surgical therapy compared to those without expression of TGF-β1 (p = 0.034).

CONCLUSIONS

We have shown that TGF-β1 expression in gastric tumor tissue with HER2/neu-negative status is of prognostic relevance in gastric cancer. The data for TGF-β1 and TGF-βRII expression showed association with clinicopathological parameters, and more precisely with the differentiation and histology type and TGF-β1-positive patient had a shorter overall survival compared with TGF-β1-negative patients.

Pharmacological inhibition of Mdm2 triggers growth arrest and promotes DNA breakage in mouse colon tumors and human colon cancer cells

The p53 tumor suppressor protein performs a number of cellular functions, ranging from the induction of cell cycle arrest and apoptosis to effects on DNA repair. Modulating p53 activity with Mdm2 inhibitors is a promising approach for treating cancer; however, it is presently unclear how the in vivo application of Mdm2 inhibitors impact the myriad processes orchestrated by p53. Since approximately half of all colon cancers (predominately cancers with microsatellite instability) are p53-normal, we assessed the anticancer activity of the Mdm2 inhibitor Nutlin-3 in the mouse azoxymethane (AOM) colon cancer model, in which p53 remains wild type. Using a cell line derived from an AOM-induced tumor, we found that four daily exposures to Nutlin-3 induced persistent p53 stabilization and cell cycle arrest without significant apoptosis. A 4-day dosing schedule in vivo generated a similar response in colon tumors; growth arrest without significantly increased apoptosis. In adjacent normal colon tissue, Nutlin-3 treatment reduced both cell proliferation and apoptosis. Surprisingly, Nutlin-3 induced a transient DNA damage response in tumors but not in adjacent normal tissue. Nutlin-3 likewise induced a transient DNA damage response in human colon cancer cells in a p53-dependent manner, and enhanced DNA strand breakage and cell death induced by doxorubicin. Our findings indicate that Mdm2 inhibitors not only trigger growth arrest, but may also stimulate p53's reported ability to slow homologous recombination repair. The potential impact of Nutlin-3 on DNA repair in tumors suggests that Mdm2 inhibitors may significantly accentuate the tumoricidal actions of certain therapeutic modalities.

Microsatellite instability of the colorectal carcinoma can be predicted in the conventional pathologic examination. A prospective multicentric study and the statistical analysis of 615 cases consolidate our previously proposed logistic regression model

High microsatellite instability (MSI-H) allows the identification of a subset of colorectal carcinomas associated with good prognosis and a higher incidence of Lynch syndrome. The aim of this work was to assess the interobserver variability and optimize our MSI-H prediction model previously published based on phenotypic features.The validation series collected from five different hospitals included 265 primary colorectal carcinomas from the same number of patients. The eight clinicopathological parameters that integrate our original model were evaluated in the corresponding centers. Homogeneity assessment revealed significant differences between hospitals in the estimation of the growth pattern, presence of Crohn-like reaction, percentage of cribriform structures, and Ki-67 positivity. Despite this observation, our model was globally able to predict MSI-H with a negative predictive value of 97.0%. The optimization studies were carried out with 615 cases and resulted in a new prediction model RERtest8, which includes the presence of tumor infiltrating lymphocytes at the expense of the percentage of cribriform structures. This refined model achieves a negative predictive value of 97.9% that is maintained even when the immunohistochemical parameters are left out, RERtest6. The high negative predictive value achieved by our models allows the reduction of the cases to be tested for MSI to less than 10%. Furthermore, the easy evaluation of the parameters included in the model renders it a useful tool for the routine practice and can reinforce other published models and the current clinical protocols to detect the subset of colorectal cancer patients bearing hereditary nonpolyposis colorectal cancers risk and/or MSI-H phenotype.

Tumor infiltrating lymphocytes: an intriguing player in the survival of colorectal cancer patients

Background

There is growing evidence that both local and systemic inflammatory responses play an important role in the progression of a variety of solid tumors. Colorectal cancer results from the cumulative effect of sequential genetic alterations, leading to the expression of tumor associated antigens possibly inducing a cellular anti-tumor immune response. It is well recognized that cytotoxic lymphocytes constitute one of the most important effector mechanisms of anti-tumor-immunity. However, their potential prognostic influence in colorectal cancer remains controversial. Aim of the study was to examine infiltration of CD3⁺ and CD8⁺ lymphocytes in colorectal cancer and their prognostic potential.

Two-hundred-fifteen colorectal cancer cases, previously analyzed for microsatellite instability (MSI), were selected for immunohistochemical detection of CD3⁺, CD8⁺ infiltration and the expression of granzyme B. Prognostic relevance was assessed by survival analysis.

Results

Strong correlations were found between the infiltration of lymphocytes and several clinicopathological variables. Survival analysis revealed that intra-epithelial infiltration of CD3⁺ and CD8⁺ T lymphocytes and stromal infiltration of CD3⁺ lymphocytes had a major impact on the patients' overall survival in the univariate analysis, however independent of their association with MSI-status. In addition, it was also demonstrated that there was an important disease specific survival advantage for patients with microsatellite stable (MSS) tumors containing intraepithelial CD8⁺ tumor infiltrating lymphocytes. When samples were analyzed for colon cancer and rectal cancer separately, the results of the overall population were confirmed in colon cancer only. When entered into a multiple Cox regression analysis adjusting for other possible important confounding factors, the strong impact of lymphocyte infiltration on overall survival was not maintained. Only early stage and young age (borderline significant for overall population only) were associated with a better overall survival (early disease with disease-free survival also).

Conclusions

In conclusion our results suggest a role for infiltrating CD3⁺ and CD8⁺ T lymphocytes in colorectal cancer whereby tumor infiltration could reflect a general principle of antitumor immunity, irrespective of the MSI-status.

Differential colorectal carcinogenesis: Molecular basis and clinical relevance

Colorectal cancer (CCR) is one of the most frequent cancers in developed countries. It poses a major public health problem and there is renewed interest in understanding the basic principles of the molecular biology of colorectal cancer. It has been established that sporadic CCRs can arise from at least two different carcinogenic pathways. The traditional pathway, also called the suppressor or chromosomal instability pathway, follows the Fearon and Vogelstein model and shows mutation in classical oncogenes and tumour suppressor genes, such as K-ras, adenomatous polyposis coli, deleted in colorectal cancer, or p53. Alterations in the Wnt pathway are also very common in this type of tumour. The second main colorectal carcinogenesis pathway is the mutator pathway. This pathway is present in nearly 15% of all cases of sporadic colorectal cancer. It is characterized by the presence of mutations in the microsatellite sequences caused by a defect in the DNA mismatch repair genes, mostly in hMLH1 or hMSH2. These two pathways have clear molecular differences, which will be reviewed in this article, but they also present distinct histopathological features. More strikingly, their clinical behaviours are completely different, having the “mutator” tumours a better outcome than the “suppressor” tumours.

A translational approach to lung cancer research: From EGFRs to Wnt and cancer stem cells

Lung cancer remains the main cause of all cancer deaths in the United States. The prognosis for non-small cell lung cancer, despite advances in current therapies, is disappointing. Fortunately, we are steadily gaining significant insights into the heterogeneous molecular pathogenesis of lung cancer, which seems to occur in a stepwise manner, mainly secondary to tobacco smoking. With the emerging power of gene expression signatures for individual lung tumors and with the advancing field of stem cell biology and the paradigm of cancer stem cells, we are most certainly paving the way to developing novel tools for the early detection, chemoprevention, and treatment of these vastly morbid pathologies with enormous global burden. We will explore some of these issues and highlight how we are starting to translate them into clinically relevant tools for lung cancer patients.

Deficient DNA mismatch repair is common in Lynch syndrome-associated colorectal adenomas

Lynch syndrome is caused by germline mutations in DNA mismatch repair (MMR) genes. Both microsatellite instability (MSI) testing and immunohistochemical analyses (IHC) of colon cancers are valuable diagnostic strategies for Lynch syndrome. We sought to determine whether these markers of MMR deficiency were also detectable in pre-cancerous colorectal adenomas. Fifteen subjects with a germline MMR gene mutation who had 44 adenomas removed during surveillance colonoscopy were identified. MSI testing and IHC for MLH1, MSH2, and MSH6 were performed. MSI was detected in 23 adenomas. There was a significant association between MSI and high-grade dysplasia (P = 0.006) and distal location (P = 0.0008). Loss of MMR protein by IHC was detected in 31 adenomas. A significant association was observed between loss of staining by IHC and high-grade dysplasia (P = 0.04). Among the 40 adenomas in which both MSI tests and IHC were performed, the presence of a germline mutation correlated with an abnormal MSI result in 58% of cases, an abnormal IHC result in 70% of cases, and either an abnormal MSI or IHC result in 73% of cases. The combination of MSI and IHC testing in colorectal adenomas is a sensitive screen for the detection of Lynch syndrome and may be particularly useful when Lynch syndrome is suspected and adenomatous polyps are the only tissues available for analysis.

Molecular analysis: microsatellity instability and loss of heterozygosity of tumor suppressor gene in hereditary non-polyposis colorectal cancers (HNPCC)

HNPCC (Hereditary non-polyposis colorectal cancers) development is caused by mutation of genes included in system of mismatch repair genes. The mutation exists at 60% of patients in hMSH2 gene, 30% in hMLH1 and 10% both in hPMS1and hPMS2 genes. RER+ exists in about 90% in hereditary non-polyposis colorectal cancer and about 15-28% in sporadic cancers. The purpose of the study was to determine highly sensitive microsatellite markers which can be fast and efficient way of microsatellite screening for detection of HNPCC patients. Moreover, we have analysed the loss of heterozygosity of tumour suppressor genes which could have the diagnostic value in detection of HPNCC patients.

Clinical relevance of EGFR- and KRAS-status in colorectal cancer patients treated with monoclonal antibodies directed against the EGFR

The epidermal growth factor receptor (EGFR) plays an important role in tumorigenesis and tumor progression of colorectal cancer (CRC). As a result, the EGFR has evolved as a relevant target in the treatment of metastatic CRC. KRAS serves as a mediator between extracellular ligand binding and intracellular transduction of signals from the EGFR to the nucleus. The presence of activating KRAS mutations has been identified as a potent predictor of resistance to EGFR-directed antibodies such as cetuximab or panitumumab. These agents should therefore be applied only in tumors with a wild-type status of the KRAS gene. Further parameters of resistance are lack of EGFR amplification, PTEN loss or BRAF mutation. However, they are less well studied or associated with less consistent data and therefore require prospective analyses before integration into clinical decision making. Future studies need to identify patterns of single or multiple mutations to further increase the power of patient selection for anti-EGFR therapy. While molecular parameters help to predict treatment efficacy upfront, skin toxicity has been accepted as an independent predictor of response during exposure to anti-EGFR therapy.

Gene expression profiling: Canonical molecular changes and clinicopathological features in sporadic colorectal cancers

AIM: To investigate alternative or subordinate pathways involved in colorectal tumorigenesis and tumor growth, possibly determining at-risk populations and predicting responses to treatment.

METHODS: Using microarray gene-expression analysis, we analyzed patterns of gene expression relative to canonical molecular changes and clinicopathological features in 84 sporadic colorectal cancer patients, standardized by tumor location. Subsets of differentially expressed genes were confirmed by real-time reverse-transcript polymerase chain reaction (RT-PCR).

RESULTS: The largest number of genes identified as being differentially expressed was by tumor location, and the next largest number by lymphovascular or neural invasion of tumor cells and by mismatch repair (MMR) defects. Amongst biological processes, the immune response was significantly implicated in entire molecular changes observed during colorectal tumorigenesis (P < 0.001). Amongst 47 differentially expressed genes, seven (PISD, NIBP, BAI2, STOML1, MRPL21, MRPL16, and MKKS) were newly found to correlate with tumorigenesis and tumor growth. Most location-associated molecular changes had distinct effects on gene expression, but the effects of the latter were sometimes contradictory.

CONCLUSION: We show that several differentially expressed genes were associated with canonical molecular changes in sporadic colorectal cancers, possibly constituting alternative or subordinate pathways of tumorigenesis. As tumor location was the dominant factor influencing differential gene expression, location-specific analysis may identify location-associated pathways and enhance the accuracy of class prediction.

Expression of mismatch repair proteins, hMLH1/hMSH2, in non-small cell lung cancer tissues and its clinical significance

BACKGROUND

hMLH1 and hMSH2 have been implicated to be involved in the DNA mismatch repair (MMR) system. The purpose of this study is to investigate the expression of hMLH1 and hMSH2 DNA MMR proteins in non-small cell lung cancer (NSCLC) tissue and to elucidate their clinical significance.

METHODS

The hMLH1 and hMSH2 protein expression was evaluated by immunohistochemistry for a consecutive series of 113 NSCLC patients. The expressions of each protein were examined for an association with the clinicopathological variables, including genetic alterations analyzed by high resolution fluorescent microsatellite analysis.

RESULTS

Regarding the hMLH1 expression, the MSI-positive patients showed significantly lower scores than the MSI-negative patients. For hMSH2 expression, the patients with a 20 or higher pack-year index (PYI) showed significantly higher scores than the patients with a PYI less than 20. The expression status of proteins did not affect both the disease free and overall survival of the patients. No significant correlation was observed among the scores for the proteins.

CONCLUSIONS

The expressions of hMLH1 and hMSH2 are independently regulated and play different roles in NSCLC. The genetic instability is possibly due to the reduced expression of hMLH1 protein, and hMSH2 expression is associated with smoking status.

Differential cancer predisposition in Lynch syndrome: insights from molecular analysis of brain and urinary tract tumors

Hereditary non-polyposis colorectal carcinoma (Lynch syndrome) is among the most common hereditary cancers in man and a model of cancers arising through deficient DNA mismatch repair (MMR). Lynch syndrome patients are predisposed to different cancers in a non-random fashion, the basis of which is poorly understood. We addressed this issue by determining the molecular profiles for different tumors from a nationwide cohort of Lynch syndrome families (approximately 150 tumors in total). We focused on some less prevalent cancers, affecting the brain (n = 7) and urinary tract (five bladder and five ureter uroepithelial cancers and four kidney adenocarcinomas), and compared their molecular characteristics to those of the most common cancers, colorectal, gastric and endometrial adenocarcinomas, from the same families. Despite origin from verified MMR gene mutation carriers, the frequency of high-level microsatellite instability in tumors varied between high (100-96% for ureter, stomach and colon), intermediate (63-60% for endometrium and bladder) and low (25-0% for kidney and brain). In contrast to gastrointestinal and endometrial carcinomas, active (nuclear) beta-catenin was rare and KRAS mutations were absent in brain and urological tumors. Compared with other tumors, frequent stabilization of p53 protein characterized urinary tract cancers. Promoter methylation of tumor suppressor genes discriminated the tumors in an organ-specific manner. Our findings suggest that different Lynch syndrome tumors develop along different routes. Uroepithelial cancers of the ureter (and bladder to lesser extent) share many characteristics of MMR deficiency-driven tumorigenesis, whereas brain tumors and kidney adenocarcinomas follow separate pathways.

Molecular prognostic markers in locally advanced colon cancer

For patients who undergo successful surgery for colon cancer, additional chemotherapy is recommended in high-risk stage II and stage III disease. Colorectal cancer prognosis is stage and grade dependent, and many tumors with similar histopathologic features show significantly different clinical outcomes. Therefore, tumor recurrence after curative resection continues to be a significant problem in the management of colon cancer, and approximately 50% of patients will develop recurrent disease. There are a few clinical and potential molecular markers that can predict clinical outcome in locally advanced colon cancer. Accordingly, the development of molecular markers of prognosis is critical in making a tailored adjuvant treatment with molecular stratification possible. Many new biomarkers have been investigated; however, none of them have yet been validated in large prospective clinical trials. To date, the two most promising and most studied mechanisms of genomic instability are chromosomal instability with deletion of chromosome 18q and 17p and microsatellite instability (MSI). Eastern Cooperative Oncology Group 5202 is a prospective clinical trial which is randomizing patients with stage II disease based on their MSI and 18q status to observation versus adjuvant chemotherapy with the intention of prospectively determining their prognostic value as molecular markers. This review will discuss the most promising molecular prognostic markers and provide an update on the most recent developments.

Mechanisms of colorectal and lung cancer prevention by vegetables: a genomic approach

Colorectal cancer (CRC) and lung cancer (LC) occur at high incidence, and both can be effectively prevented by dietary vegetable consumption. This makes these two types of cancer highly suitable for elucidating the underlying molecular mechanisms of cancer chemoprevention. Numerous studies have shown that vegetables exert their beneficial effects through various different mechanisms, but effects on the genome level remain mostly unclear. This review evaluates current knowledge on the mechanisms of CRC and LC prevention by vegetables, thereby focusing on the modulation of gene and protein expressions. The majority of the effects found in the colon are changes in the expression of genes and proteins involved in apoptosis, cell cycle, cell proliferation and intracellular defense, in favor of reduced CRC risk. Furthermore, vegetables and vegetable components changed the expression of many more genes and proteins involved in other pathways for which biologic meaning is less clear. The number of studies investigating gene and protein expression changes in the lungs is limited to only a few in vitro and animal studies. Data from these studies show that mostly genes involved in biotransformation, apoptosis and cell cycle regulation are affected. In both colon and lungs, genomewide analyses of gene and protein expression changes by new genomics and proteomics technologies, as well as the investigation of whole vegetables, are few in number. Further studies applying these 'omics' approaches are needed to provide more insights on affected genetic/biologic pathways and, thus, in molecular mechanisms by which different chemopreventive compounds can protect against carcinogenesis. Particularly studies with combinations of phytochemicals and whole vegetables are needed to establish gene expression changes in the colon, but especially in the lungs.

Patterns of K-ras mutation in colorectal carcinomas from Iran and Italy (a Gruppo Oncologico dell'Italia Meridionale study): influence of microsatellite instability status and country of origin

BACKGROUND

K-ras mutations are a key step in colorectal cancer progression. Such mutations have been widely studied in case series from Western countries but there are few data on the rate and spectrum of mutations in tumors from countries where the epidemiological features of the disease are different.

PATIENTS AND METHODS

Tumor samples from 182 Iranian colorectal cancer patients (170 sporadic cases and 12 HNPCC cases) were screened for K-ras mutations at codons 12, 13 and 61 by sequencing analysis. The cases were also characterized for microsatellite instability at mononucleotide repeats by PCR and fragment analysis, and classified according to microsatellite instability status. The frequency and the spectrum of K-ras mutations were compared with those observed in a series of colorectal cancer patients from Italy.

RESULTS

K-ras mutations were observed in 68/182 (37.4%) cases. Mutation frequencies were similar in HNPCC-associated, sporadic MSI-H and sporadic microsatellite-stable (MSS) tumors. However, the G13D substitution was more frequent in HNPCC (3/4, 75%) and sporadic MSI-H (7/11, 63.6%) tumors compared to sporadic MSS tumors (11/53, 20.4%) (P <0.01). Comparison of mutations in the two series from Iran and Italy showed a significantly higher frequency of G13D among Italian patients.

CONCLUSIONS

While the frequency of K-ras mutations could be similar, the mutational spectrum could be differentially influenced by genetic and environmental factors.

Frequency of constitutional MSH6 mutations in a consecutive series of families with clinical suspicion of HNPCC

A large majority of constitutional mutations in hereditary non-polyposis colorectal cancer (HNPCC) are because of the MHL 1 or MSH 2 genes. In a lower fraction of cases, another gene of the mismatch repair (MMR) machinery, MSH6, may be responsible. Families with MSH6 mutations are difficult to recognize, as microsatellite instability (MSI) may not be detectable and immunohistochemistry (IHC) may give ambiguous results. In the present study, we proposed (i) to determine the frequency of MSH6 mutations in a selected population of colorectal cancer patients obtained from a tumor registry, (ii) to assess whether IHC is a suitable tool for selecting and identifying MSH6 mutation carriers. One hundred neoplasms of the large bowel from suspected HNPCC families were analyzed for MSI (BAT 25 and BAT 26 markers) and immunohistochemical expression of the MSH6 protein. We found on 12 tumors (from different families) showing instability or lack of MSH6 expression. Among these, four potentially pathogenic MSH6 mutations were detected (del A at 2984; del TT at 3119; del AGG cod 385; and del CGT cod 1242) by direct gene sequencing. These represented 12.9% of all families with constitutional mutations of the DNA MMR genes. Thus, some 5% of all HNPCC families are featured by constitutional mutation of the MSH6 gene. This appears, however, as a minimum estimate; routine use of IHC and the study of large numbers of individuals and families with little or no evidence of Lynch syndrome might reveal that mutation of this gene account for a large fraction of HNPCC.

p53 and mdm2 expression in colorectal carcinoma: a correlative analysis with clinical staging and histological parameters

Colorectal carcinoma (CRC) is rare in the Indian subcontinent. The two-hit carcinogenic theory has been well established from the turn of this century, in which p53 is described as a late marker in colorectal carcinogenesis, and murine double minute 2 (mdm2) has not yet been correlated with colorectal carcinoma. With the recent introduction of anti-mdm2 oligonucleotides, it is apparent that if its role can be established in colorectal carcinogenesis, the DNA conservation of the wild p53 strain would be achieved therapeutically because mdm2 conserves the wild p53 strain. We studied 32 cases with adequate number of controls and found a positive correlation (P = .001) between these proteins. These proteins were expressed in tumor adjacent to the hyperplastic mucosa, dysplastic mucosa, and aberrant crypt foci, unlike in studies in the West. The expression of these proteins was correlated with aggressive tumor behavior. All these indicate significant diagnostic, therapeutic, and prognostic roles for these proteins.

Molecular Analysis of Colorectal Cancer Tumors from Patients with Mismatch Repair–Proficient Hereditary Nonpolyposis Colorectal Cancer Suggests Novel Carcinogenic Pathways

PURPOSE

A subset of colorectal cancers (CRC) arises in families that, despite fulfilling clinical criteria for hereditary nonpolyposis colorectal cancer (HNPCC), do not show evidence of a mismatch repair (MMR) deficiency. The main objective of this study was to characterize these tumors at the molecular level.

EXPERIMENTAL DESIGN

After comprehensive germ line mutation scanning, microsatellite analysis, and MMR protein expressions, we selected a well-defined cohort of 57 colorectal tumors with no evidence of MMR defects. In this group of tumors, we analyzed KRAS, BRAF, and APC somatic mutations, as well as methylguanine methyltransferase (MGMT) and beta-catenin expression. We correlated these alterations with clinicopathologic data and explored the relationship between KRAS G > A transitions and lack of MGMT expression.

RESULTS

The mutation profile at the RAS/RAF/MAPK pathway mimics sporadic microsatellite-stable CRCs. We found an average age of diagnosis 10 years older in KRAS-mutated patients (P = 0.001). In addition, we show that KRAS G > A transitions are actively selected by tumors, regardless of MGMT status. Similarities with HNPCC high-microsatellite instability tumors are observed when APC data are analyzed. The APC mutation rate was low and small insertions/deletions accounted for 70% of the alterations. In addition, we found a low frequency of beta-catenin nuclear staining. Finally, we did not find evidence of tumors arising in individuals from the same family sharing molecular features.

CONCLUSIONS

We show evidence that CRC tumors arising in HNPCC families without MMR alterations have distinctive molecular features. Overall, our work shows that systematic analysis of somatic alterations in a well-defined subset of CRCs is a good approach to provide new insights into the mechanisms of colorectal carcinogenesis.

Clinical relevance of E2F family members in ovarian cancer--an evaluation in a training set of 77 patients

PURPOSE

The major obstacle in treating ovarian cancer is the rapid development of platinum resistance during therapy. Deregulation of members of the E2F family of transcription factors is crucially involved in carcinogenesis and probably in mechanisms underlying platinum resistance. We therefore investigated the relevance of the whole set of E2F family members in predicting clinical outcome and their significance in predicting platinum resistance.

EXPERIMENTAL DESIGN

Real-time PCR of all E2F family members was done from 77 ovarian carcinomas, defined as our training set, and 8 healthy control samples. The correlation with clinicopathologic characteristics, platinum resistance, and survival was investigated. Furthermore, the cross-talk of E2F family members was assessed for its value in predicting survival and platinum resistance.

RESULTS

The proliferation-promoting E2F1 and E2F2 were associated with grade 3 tumors and residual disease >2 cm in diameter after initial surgery. Survival analyses showed low expression of E2F1 or E2F2 to be significantly associated with favorable disease-free and overall survival (E2F1, P = 0.039 and 0.047, respectively; E2F2, P = 0.009 and 0.006, respectively). In contrast, high expression of inhibiting E2F4 or E2F7 predicted favorable disease-free and overall survival (E2F4, P = 0.047 and 0.042, respectively; E2F7, P = 0.048 and 0.042, respectively). A high E2F2 to E2F4 ratio was the most valuable prognostic variable for disease-free survival in multivariate analysis (hazard ratio, 6.494; P = 0.002). Tumors considered platinum resistant were associated with lower E2F4 and E2F7 expression (P = 0.012 and 0.009, respectively) compared with platinum-sensitive tumors. Again, ratios of E2F1 or E2F2 to E2F7 were the most favorable variables in predicting platinum resistance.

CONCLUSIONS

We here show that deregulation of both proliferation-promoting and proliferation-inhibiting E2F transcription factors and their cross-talk is crucially involved in the tumor biology of ovarian cancer and influences clinical outcome. Furthermore, down-regulation of E2F7 may contribute to mechanisms underlying platinum resistance, and calculation of ratios of proliferation-promoting E2F1 to E2F7 could serve as a putative predictor of platinum resistance.

Mismatch repair polymorphisms and the risk of colorectal cancer

Rare germline variants in mismatch repair genes have been linked to hereditary nonpolyposis colorectal cancer; however, it is unknown whether common polymorphisms in these genes alter the risk of colorectal cancer. To examine the association between common variants in mismatch repair genes and colorectal cancer, we conducted a case-cohort study within the CLUE II cohort. Four single nucleotide polymorphisms in 3 mismatch repair genes (MSH3 R940Q, MSH3 T1036A, MSH6 G39E and MLH1 I219V) were genotyped in 237 colorectal cancer cases and a subcohort of 2,189 participants. Incidence rate ratios (RRs) and 95% confidence intervals (95% CIs) for each polymorphism were estimated. The MSH3 1036A variant was found to be associated with an increased risk of colorectal cancer (RR=1.28, 95% CI: 0.94-1.74 and RR=1.65, 95% CI: 1.01-2.70 for the AT and TT genotypes, respectively, with p(trend)=0.02), particularly proximal colon cancer. Although the MSH3 940Q variant was only weakly associated with colorectal cancer overall (p(trend)=0.07), it was associated with a significant increased risk of proximal colon cancer (RR=1.69, 95% CI: 1.10-2.61 and RR=2.68, 95% CI: 0.96-7.47 for the RQ and QQ genotypes, respectively with p(trend)=0.005). Processed meat intake appeared to modify the association between the MSH3 polymorphisms and colorectal cancer (p(interaction) < 0.10 for both). No association was observed with the MSH6 and MLH1 polymorphisms overall. This study suggests that common polymorphisms in the mismatch repair gene, MSH3, may increase the risk of colorectal cancer, especially proximal colon cancer.

Novel therapies targeting signaling pathways in lung cancer

Despite advances in chemotherapy, the prognosis for advanced non-small-cell lung cancer (NSCLC) remains dismal. Increasing understanding of the biological processes responsible for lung carcinogenesis has led to development of new therapeutic strategies targeting this disease at a molecular level. This article examines the molecular events believed to lead to cellular changes in lung cancer, and how knowledge of these is used to develop new agents used individually or in combination with available cytotoxic drugs to improve survival. Finally, it explores how a deeper understanding of the embryonic signaling pathways responsible for airway epithelial repair and tumorogenesis, such as Hedgehog (Hh), Notch, and Wingless (Wnt), can lead to the development of newer and more specific therapies for lung cancer.

Tumour budding in colorectal carcinoma

The term tumour budding denotes that at the invasion front of colorectal adenocarcinomas tumour cells, singly or in small aggregates, become detached from the neoplastic glands. This morphological feature is increasingly being recognized as a strong and robust adverse prognostic factor. Biologically, tumour budding is closely related to the epithelial-mesenchymal transition. In this review the morphological features of tumour budding are discussed, as observed by the surgical pathologist reporting colorectal carcinoma resection specimens. The morphological features are put into context with the rapidly expanding knowledge of the epithelial-mesenchymal transition in general, and the molecular pathology of colorectal carcinoma in particular. Finally, a systematic analysis of the relevant published clinicopathological studies emphasizes the potential of tumour budding as a prognostic factor for routine surgical pathology.

Tumour budding in colorectal carcinoma

The term tumour budding denotes that at the invasion front of colorectal adenocarcinomas tumour cells, singly or in small aggregates, become detached from the neoplastic glands. This morphological feature is increasingly being recognized as a strong and robust adverse prognostic factor. Biologically, tumour budding is closely related to the epithelial-mesenchymal transition. In this review the morphological features of tumour budding are discussed, as observed by the surgical pathologist reporting colorectal carcinoma resection specimens. The morphological features are put into context with the rapidly expanding knowledge of the epithelial-mesenchymal transition in general, and the molecular pathology of colorectal carcinoma in particular. Finally, a systematic analysis of the relevant published clinicopathological studies emphasizes the potential of tumour budding as a prognostic factor for routine surgical pathology.

Classification of colorectal cancer based on correlation of clinical, morphological and molecular features

Over the last 20 years it has become clear that colorectal cancer (CRC) evolves through multiple pathways. These pathways may be defined on the basis of two molecular features: (i) DNA microsatellite instability (MSI) status stratified as MSI-high (MSI-H), MSI-low (MSI-L) and MS stable (MSS), and (ii) CpG island methylator phenotype (CIMP) stratified as CIMP-high, CIMP-low and CIMP-negative (CIMP-neg). In this review the morphological correlates of five molecular subtypes are outlined: Type 1 (CIMP-high/MSI-H/BRAF mutation), Type 2 (CIMP-high/MSI-L or MSS/BRAF mutation), Type 3 (CIMP-low/MSS or MSI-L/KRAS mutation), Type 4 (CIMP-neg/MSS) and Type 5 or Lynch syndrome (CIMP-neg/MSI-H). The molecular pathways are determined at an early evolutionary stage and are fully established within precancerous lesions. Serrated polyps are the precursors of Types 1 and 2 CRC, whereas Types 4 and 5 evolve through the adenoma-carcinoma sequence. Type 3 CRC may arise within either type of polyp. Types 1 and 4 are conceived as having few, if any, molecular overlaps with each other, whereas Types 2, 3 and 5 combine the molecular features of Types 1 and 4 in different ways. This approach to the classification of CRC should accelerate understanding of causation and will impact on clinical management in the areas of both prevention and treatment.

Genetic alterations in sporadic and hereditary colorectal cancer: implementations for screening and follow-up

The genetics underlying an inherited predisposition to cancer are rapidly being uncovered. This fact may ultimately lead to the routine use of molecular tools to diagnose these disorders, and establish interventions to prevent the development of cancer. Among the multiple cancer family syndromes, several are known to be associated with the development of colon cancer. These disorders may be diagnosed during evaluation of the index patient or during screening of family members who are at risk. Although the effectiveness of screening and surveillance strategies is unproven in controlled clinical trials for any of these syndromes, the high cancer risk warrants screening, and reasonable recommendations can be made. Several other genetic syndromes are associated with gastrointestinal polyposis. The risk of colon cancer in these diseases is uncertain, and may not be increased and they are not mentioned in this review. Examples include Cowden disease, intestinal ganglioneuromatosis, Ruvalcaba-Myhre-Smith syndrome, Devon family syndrome, and Cronkite-Canada syndrome.

Chemotherapeutic agents for colorectal cancer with a defective mismatch repair system: The state of the art

Mismatch repair (MMR) proteins are capable of recognizing and processing not only single base-pair mismatches and insertion-deletion loops that occur during DNA replication, but also adducts in DNA resulting from treatment with cancer chemotherapy agents. MMR deficiency leads to microsatellite instability (MSI) and results in resistance to antimetabolites, alkylating and platinating agents, DNA minor groove binders, and inhibitors of topoisomerases. Therefore, anticancer agents that can be recommended for use in MMR deficient colorectal cancers are those that exert their cytotoxicity regardless of the MMR status. These include some alkylating drugs, brostacillin, gemcytabine, photodynamic therapy, taxanes. An approach that is currently receiving much attention is the use of agents such as 5-azacytidine, an inhibitor of the DNA methyltransferases, in combination with inhibitors of histone de-acetylation, to restore the MMR function. A strong anti-proliferative efficacy with a relatively low direct cytotoxicity, obtainable with oloumicine and roscovitine (selective cyclin-dependent kinases inhibitors) can represent a new expedient for the therapeutic treatment of MMR deficient colorectal cancers. The question of how MMR defects modulate the response to chemotherapeutics deserves further investigation, to enable a more aware choice of cancer treatment.

Increased risk for abnormalities on perioperative colon screening in patients with microsatellite instability–positive endometrial carcinoma

Microsatellite instability (MSI) is a feature of certain hereditary and sporadic endometrial and colon cancers. We set out to determine whether molecular stratification of endometrial cancers based on tumor MSI status could help identify patients at increased risk for abnormalities found on perioperative colon screening. From a prospectively accrued series of 413 patients, medical records were reviewed from 94 patients with MSI positive (MSI+) and 94 patients with MSI negative (MSI−) endometrial cancers, matched by year of diagnosis. We reviewed clinicopathologic data and results of perioperative colon screening. Differences were analyzed using Fisher exact test and logistic regression analysis. There were no significant clinicopathologic differences between the two cohorts. Sixty-five percent of patients in each group underwent perioperative colon screening. However, patients with MSI+ cancers had a twofold increase in the frequency of colonic abnormalities (30% versus 14.8%, P= 0.044) over those with MSI− cancers. Furthermore, the only primary colon cancers (N= 2) were found in women with MSI+ endometrial cancers that were unmethylated at the MLH1 promoter. Our data suggest that patients with MSI+ endometrial cancers are at increased risk for abnormalities on perioperative colon screening. Those with MSI+MLH1 unmethylated cancers appear to be at highest risk.

Overexpression of the receptor for hyaluronic acid mediated motility is an independent adverse prognostic factor in colorectal cancer

RHAMM, a member of the microtubule-associated protein family that interacts with the mitogen-activated protein kinase pathway, is associated with tumor progression, aggressive disease and shortened survival in several tumor types. This study aimed to determine the prognostic value of RHAMM in colorectal cancer (CRC). A series of 1420 unselected, nonconsecutive CRC resections were subdivided into three groups: (1) DNA mismatch repair (MMR)-proficient, (2) MLH1 negative and (3) presumed Lynch syndrome. Immunohistochemical analysis of RHAMM expression (0 vs >0%), increasing expression (increasing percentage positivity) and complete expression (100 vs <100%) was performed using tissue microarray technique and the results were correlated with clinicopathological parameters. Fifty-seven tissue samples of normal colonic mucosa were included as a control group. In a univariate analysis increasing and complete expression of RHAMM were associated with higher N stage (P=0.023 and 0.021) and worse survival (P<0.0001) in MMR-proficient CRC. Complete expression of RHAMM was associated with worse survival in presumed Lynch syndrome (P=0.016). In MLH1-negative CRC there was no association between RHAMM expression and the clinicopathological features. In a multivariate analysis, increasing RHAMM expression was an independent adverse prognostic factor in MMR-proficient CRC (P<0.0001) and complete expression in MMR-proficient CRC and presumed Lynch syndrome (P<0.0001 and P=0.031, respectively). Nuclear pERK expression was associated with increasing RHAMM expression in MMR-proficient CRC (P=0.012) and with complete RHAMM expression in presumed HNPCC (P=0.03). Increasing and complete RHAMM expressions are independent adverse prognostic factors in MMR-proficient CRC and presumed Lynch syndrome.

Bronchioloalveolar carcinoma: a review

Bronchioloalveolar carcinoma (BAC) is classified as a subset of lung adenocarcinoma but has a distinct clinical presentation, tumor biology, response to therapy, and prognosis compared with other subtypes of non-small-cell lung carcinoma (NSCLC). Bronchioloalveolar carcinoma disproportionately affects women, never-smokers, and Asians and is characterized by growth along alveolar septae without evidence of stromal, vascular, or pleural invasion. Although pure BAC accounts for approximately 4% of lung cancers, tumors with histologically mixed BAC and adenocarcinoma account for > 20% of all NSCLCs, and the incidence of BAC might be increasing. Bronchioloalveolar carcinoma histology is most commonly found in small lesions identified incidentally on chest radiographs or computed tomography scans and might represent a precursor lesion to invasive adenocarcinoma. As with other subsets of NSCLC, surgical resection is the only potentially curative treatment. Patients with unresectable BAC are more likely to respond to the epidermal growth factor receptor tyrosine kinase inhibitors gefitinib and erlotinib than patients with other subtypes of NSCLC. Stage for stage, patients with BAC have a higher rate of long-term survival but might have an increased rate of intrathoracic recurrence than patients with other subtypes of NSCLC.