Statistical strategies to improve the efficiency of molecular studies of colorectal cancer prognosis

The evaluation of tumour molecular markers may be beneficial in prognosis and predictive in therapy. We develop a stopping rule approach to assist in the efficient utilisation of resources and samples involved in such evaluations. This approach has application in determining whether a specific molecular marker has sufficient variability to yield meaningful results after the evaluation of molecular markers in the first n patients in a study of sample size N (n⩽N). We evaluated colorectal tumours for mutations (microsatellite instability, K-ras, B-raf, PI3 kinase, and TGFβR-II) by PCR and protein markers (Bcl2, cyclin D1, E-cadherin, hMLH1, ki67, MDM2, and P53) by immunohistochemistry. Using this method, we identified and abandoned potentially uninformative molecular markers in favour of more promising candidates. This approach conserves tissue resources, time, and money, and may be applicable to other studies

In vivo activation of mitogen-activated protein kinases in rat intestinal neoplasia

AbstractBACKGROUND & AIMS: To investigate whether mitogen-activated protein kinase (MAPK) cascades might play a role in the progression of colon cancer, c-Jun N-terminal kinase (JNK) and extracellular signal regulating kinase (ERK) activity during colonic tumorigenesis were examined.METHODS: The 1,2-dimethylhydrazine (DMH)-induced colon carcinoma model was used to study the activation of these kinases during intestinal carcinogenesis. Male Sprague-Dawley rats were injected with DMH for 24 weeks. Normal-appearing intestinal mucosa from control and treated animals and DMH-induced intestinal tumors were assayed for JNK and ERK activity using solid phase in vitro kinase assays. Tumors were typed for mutations in the K-ras gene.RESULTS: There was little or no difference in JNK and ERK activity in hyperproliferative mucosa from DMH-treated animals compared with normal mucosa from control animals. However, in 16 colonic neoplasms, an average of 23-fold and 29-fold increases in JNK and ERK activities were observed, respectively, over control levels. In addition, activating protein-1 binding was strongly induced in the colonic tumors. Activation did not correlate with the presence of mutations in K-ras.CONCLUSIONS: Both the JNK and ERK MAPKs are highly activated during late progression of colorectal carcinoma. This change is dependent on the tumorigenic state rather than changes in proliferation.(Gastroenterology 1997 Nov;113(5):1589-98

Markers of tyrosine kinase activity in eosinophilic esophagitis: a pilot study of the FIP1L1-PDGFRα fusion gene, pERK 1/2, and pSTAT5: Tyrosine kinase markers in EoE

The pathogenesis of eosinophilic esophagitis (EoE) is incompletely understood. In certain eosinophilic diseases, activation of tyrosine kinase after fusion of the Fip1-like-1 and platelet-derived growth factor receptor-α genes (F-P fusion gene) mediates eosinophilia via downstream effectors such as extracellular-regulated kinase (ERK1/2) and signal transducers and activators of transcription (STAT5). This mechanism has not been examined in EoE. Our aim was to detect the F-P fusion gene, pERK1/2, and pSTAT5 in esophageal tissue from patients with EoE, gastroesophageal reflux disease (GERD), and normal controls

KRAS/BRAF mutation status and ERK1/2 activation as biomarkers for MEK1/2 inhibitor therapy in colorectal cancer

Phase II clinical trials of MEK inhibitors are ongoing and ERK1/2 activation is frequently used as a biomarker. In light of the mutational activation of BRAF and KRAS in colorectal cancer (CRC), inhibitors of the Raf-MEK-ERK mitogen-activated protein kinase are anticipated to be promising. Previous studies in pancreatic cancer have found little correlation between BRAF/KRAS mutation status and ERK1/2 activation, suggesting that identifying biomarkers of MEK inhibitor response may be more challenging than previously thought. The purpose of this study was to evaluate the effectiveness of MEK inhibitor therapy for CRC and BRAF/KRAS mutation status and ERK1/2 activation as biomarkers for MEK inhibitor therapy. First, we found that MEK inhibitor treatment impaired the anchorage-independent growth of nearly all KRAS/BRAF mutant, but not wild-type, CRC cells. There was a correlation between BRAF, but not KRAS, mutation status and ERK1/2 activation. Second, neither elevated ERK1/2 activation nor reduction of ERK1/2 activity correlated with MEK inhibition of anchorage-independent growth. Finally, we validated our cell line observations and found that ERK1/2 activation correlated with BRAF, but not KRAS, mutation status in 190 patient CRC tissues. Surprisingly, we also found that ERK activation was elevated in normal colonic epithelium, suggesting that normal cell toxicity may be a complication for CRC treatment. Our results suggest that although MEK inhibitors show promise in CRC, KRAS/BRAF mutation status, but not ERK activation as previously thought, may be useful biomarkers for MEK inhibitor sensitivity

Circulating Levels of Inflammatory Cytokines and Risk of Colorectal Adenomas

The association between obesity and colorectal neoplasia may be mediated by inflammation. Circulating levels of C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) are elevated in the obese. Adipose tissue can produce and release the inflammatory cytokines that are potentially procarcinogenic. We examined circulating levels of CRP, IL-6, and TNF-α in relation to risk factors and the prevalence of colorectal adenomas. Plasma levels of CRP, IL-6, and TNF-α were quantified in 873 participants (242 colorectal adenoma cases and 631 controls) in a colonoscopy-based cross-sectional study conducted between 1998 and 2002. Multivariable logistic regression was used to estimate associations between levels of inflammatory cytokines, colorectal adenomas, and known risk factors. Several known risk factors for colorectal neoplasia were associated with higher levels of inflammatory cytokines such as older age, current smoking, and increasing adiposity. The prevalence of colorectal adenomas was associated with higher concentrations of IL-6 and TNF-α, and to a lesser degree, with CRP. For IL-6, adjusted odds ratios for colorectal adenomas were 1.78 (95% confidence interval [CI]: 1.18–2.68) for the second highest plasma level, and 1.84 (95% CI: 1.24– 2.74) for the highest level compared with the reference level. A similar association was found with TNF-α, with adjusted odds ratios of 1.54 (95% CI: 1.02–2.33) and 1.65 (95% CI: 1.09–2.50), respectively. Our findings indicate that inflammation might be involved in the early development of colorectal neoplasia, and suggest that systemic inflammatory cytokines might be an indicator of obesity and other risk factors for colorectal neoplasia

Nonsteroidal anti-inflammatory drugs, apoptosis, and colorectal adenomas

AbstractBackground & Aims: Observational studies indicate that nonsteroidal anti-inflammatory drugs (NSAIDs) reduce the risk of colorectal neoplasia. The mechanism of this effect could be via modification of apoptotic activity in colonic mucosa. We examined grossly normal rectal mucosa in patients with adenomas and adenoma-free controls to assess the associations between NSAID use, adenomatous polyps, and apoptosis. Methods: Study participants were drawn from consecutive patients who underwent colonoscopy between August, 1998, and February, 2000. Biopsy specimens were taken from normal-appearing rectal mucosa 10 cm from the anal verge. Apoptosis was scored from coded, H&E-stained sections using morphologic methods. Proliferation was scored using whole crypt mitotic counts. Univariate and multivariate regression analyses were conducted to estimate crude and adjusted odds ratios (ORs). Results: There were 226 patients with adenomas and 493 adenoma-free controls. After adjusting for sex, age, race, and body mass index (BMI), individuals in the highest tertile of regular NSAID use were substantially less likely to have adenomas (OR 0.4; 95% CI: 0.2–0.7) compared with occasional or nonusers. Similarly, compared with the lowest tertile, persons in the highest tertile of rectal mucosal apoptotic activity were much less likely to have adenomas (OR 0.12; 95% CI: 0.07–0.20). NSAID use and apoptotic activity were not correlated (r = 0.10). Mucosal proliferation was not related to adenomas or NSAID use. Conclusions: Our observations suggest that NSAID use and higher levels of mucosal apoptosis are independently associated with a lower prevalence of adenomas. The study shows a strong field effect for apoptosis.GASTROENTEROLOGY 2002;123:1770-177

Intestinal Inflammation Targets Cancer-Inducing Activity of the Microbiota

Inflammation alters host physiology to promote cancer, as seen in colitis-associated colorectal cancer (CRC). Here we identify the intestinal microbiota as a target of inflammation that impacts the progression of CRC. High-throughput sequencing revealed that inflammation modifies gut microbial composition in colitis-susceptible interleukin-10-deficient (Il10−/−) mice. Monocolonization with the commensal Escherichia coli NC101 promoted invasive carcinoma in azoxymethane (AOM)-treated Il10−/− mice. Deletion of the polyketide synthase (pks) genotoxic island from E. coli NC101 decreased tumor multiplicity and invasion in AOM/Il10−/− mice, without altering intestinal inflammation. Mucosa-associated pks+ E. coli were found in a significantly high percentage of inflammatory bowel disease (IBD) and CRC patients. This suggests that in mice, colitis can promote tumorigenesis by altering microbial composition and inducing the expansion of microorganisms with genotoxic capabilities

Nongenetic Determinants of Risk for Early-Onset Colorectal Cancer

Background: Incidence of early-onset (younger than 50 years of age) colorectal cancer (CRC) is increasing in many countries. Thus, elucidating the role of traditional CRC risk factors in early-onset CRC is a high priority. We sought to determine whether risk factors associated with late-onset CRC were also linked to early-onset CRC and whether association patterns differed by anatomic subsite. Methods: Using data pooled from 13 population-based studies, we studied 3767 CRC cases and 4049 controls aged younger than 50 years and 23 437 CRC cases and 35 311 controls aged 50 years and older. Using multivariable and multinomial logistic regression, we estimated odds ratios (ORs) and 95% confidence intervals (CIs) to assess the association between risk factors and early-onset CRC and by anatomic subsite. Results: Early-onset CRC was associated with not regularly using nonsteroidal anti-inflammatory drugs (OR = 1.43, 95% CI = 1.21 to 1.68), greater red meat intake (OR = 1.10, 95% CI = 1.04 to 1.16), lower educational attainment (OR = 1.10, 95% CI = 1.04 to 1.16), alcohol abstinence (OR = 1.23, 95% CI = 1.08 to 1.39), and heavier alcohol use (OR = 1.25, 95% CI = 1.04 to 1.50). No factors exhibited a greater excess in early-onset compared with late-onset CRC. Evaluating risks by anatomic subsite, we found that lower total fiber intake was linked more strongly to rectal (OR = 1.30, 95% CI = 1.14 to 1.48) than colon cancer (OR = 1.14, 95% CI = 1.02 to 1.27; P = .04). Conclusion: In this large study, we identified several nongenetic risk factors associated with early-onset CRC, providing a basis for targeted identification of those most at risk, which is imperative in mitigating the rising burden of this disease

Influence of Race on Microsatellite Instability and CD8+ T Cell Infiltration in Colon Cancer

African American patients with colorectal cancer show higher mortality than their Caucasian counterparts. Biology might play a partial role, and prior studies suggest a higher prevalence for microsatellite instability (MSI) among cancers from African Americans, albeit patients with MSI cancers have improved survival over patients with non-MSI cancers, counter to the outcome observed for African American patients. CD8+ T cell infiltration of colon cancer is postively correlated with MSI tumors, and is also related to improved outcome. Here, we utilized a 503-person, population-based colon cancer cohort comprising 45% African Americans to determine, under blinded conditions from all epidemiological data, the prevalence of MSI and associated CD8+ T cell infiltration within the cancers. Among Caucasian cancers, 14% were MSI, whereas African American cancers demonstrated 7% MSI (P = 0.009). Clinically, MSI cancers between races were similar; among microsatellite stable cancers, African American patients were younger, female, and with proximal cancers. CD8+ T cells were higher in MSI cancers (88.0 vs 30.4/hpf, P<0.0001), but was not different between races. Utilizing this population-based cohort, African American cancers show half the MSI prevalence of Caucasians without change in CD8+ T cell infiltration which may contribute towards their higher mortality from colon cancer

Genetic Associations in the Vitamin D Receptor and Colorectal Cancer in African Americans and Caucasians

Low vitamin D levels are associated with an increased incidence of colorectal cancer (CRC) and higher mortality from the disease. In the US, African Americans (AAs) have the highest CRC incidence and mortality and the lowest levels of vitamin D. Single nucleotide polymorphisms (SNPs) in the vitamin D receptor (VDR) gene have been previously associated with CRC, but few studies have included AAs. We studied 795 AA CRC cases and 985 AA controls from Chicago and North Carolina as well as 1324 Caucasian cases and 990 Caucasian controls from Chicago and Spain. We genotyped 54 tagSNPs in VDR (46586959 to 46521297 Mb) and tested for association adjusting for West African ancestry, age, gender, and multiple testing. Untyped markers were imputed using MACH1.0. We analyzed associations by gender and anatomic location in the whole study group as well as by vitamin D intake in the North Carolina AA group. In the joint analysis, none of the SNPs tested was significantly associated with CRC. For four previously tested restriction fragment length polymorphisms, only one (referred to as ApaI), tagged by the SNP rs79628898, had a nominally significant p-value in AAs; none of these polymorphisms were associated with CRC in Caucasians. In the North Carolina AAs, for whom we had vitamin D intake data, we found a significant association between an intronic SNP rs11574041 and vitamin D intake, which is evidence for a VDR gene-environment interaction in AAs. In summary, using a systematic tagSNP approach, we have not found evidence for significant associations between VDR and CRC in AAs or Caucasians