Altered gene expression in normal colonic mucosa of individuals with polyps of the colon

A Four-Gene Panel in Rectal Swab Samples as a Biomarker for Colorectal Cancer Screening

BACKGROUND

The dysregulation of gene expression is one of the key molecular features of colorectal cancer (CRC) development. This study aimed to investigate whether such dysregulation is reflected in rectal swab specimens of CRC patients and to evaluate its potential as a non-invasive approach for screening.

METHODS

We compared the expression level of 14 CRC-associated genes in tumor and adjacent non-tumor tissue of CRC patients and examined the correlation of their levels in tissue with paired rectal swab specimens. The level of these 14 genes in rectal swab specimens was compared among patients with CRC or polyp and control subjects, and the diagnostic potential of each dysregulated gene and the gene panel were evaluated.

RESULTS

The expression of CXCR2, SAA, COX1, PPARδ, PPARγ, Groγ, IL8, p21, c-myc, CD44 and CSF1 was significantly higher in CRC, and there was a significant correlation in the levels of most of them between the CRC and rectal swab specimens. In the training study, we showed that CD44, IL8, CXCR2 and c-myc levels were significantly higher in the rectal swab specimens of the CRC patients. Such result was confirmed in the validation study. A panel of these four genes was developed, and ROC analysis showed that this four-gene panel could identify CRC patients with an AUC value of 0.83 and identify overall polyp and precancerous adenoma patients with AUC values of 0.6522 and 0.7322, respectively. Finally, the predictive study showed that the four-gene panel demonstrated sensitivities of 63.6%, 76.9% and 88.9% in identifying overall polyp, precancerous adenoma and CRC patients, respectively, whereas the specificity for normal subjects was 72.2%.

CONCLUSION

The expression of CRC-associated genes in rectal swab specimens reflects the dysregulation status in colorectal tissue, and the four-gene panel is a potential non-invasive biomarker for early precancerous adenoma and CRC screening.

Differential profile of protumor immunological factors between the tumor site and the tumor-free site - predictive potential of IL-8 and COX2 for colorectal cancer and metastasis

To study the role of host immune surveillance in the initiation and progression of colorectal cancer (CRC), a set of protumor immunological factors was determined by quantitative real-time PCR (q-PCR) between the primary tumor and the adjacent tumor-free site tissues in 63 patients with colorectal neoplasms. Results showed that expression levels of interleukin (IL)-1β, IL-6, IL-8, IL-17A, IL-23, and cyclooxygenase 2 (COX2) mRNAs, except transforming growth factor beta (TGFβ), in adenoma tissues were significantly higher than that in relative adjacent tissues. Difference of immunological factor levels between adenoma and adjacent tissues (Δ values) was in an order of ΔIL-8 > ΔIL-6 > ΔIL-17A > ΔIL-1β > ΔCOX2 > ΔIL-23; Analysis showed that the value of ΔCOX2 correlated to the grade of dysplastic degree in patients with adenoma. Notably, levels of all these immunological factors in CRC tissues were continuously increased, the order of values of Δ immunological factors was ΔIL-8 > ΔCOX2 > ΔIL-6 > ΔIL-1β > ΔIL-17A > ΔIL-23 > ΔTGFβ. Further analysis revealed that increased value of Δ IL-1β was associated with advanced TNM stage, a higher value of Δ COX2 tended to predicate a deeper degree of tumor invasion; and higher values of Δ IL-1β, IL-6 and COX2 closely correlated to lymph node metastasis in patients with CRC. In addition, the ratio of ΔIL-8/ΔTGFβ was most obvious changed factor and associated with node metastasis in patients with CRC. Therefore, we concluded that the difference of protumor immunological factor levels between the primary tumor site and tumor-free site along the adenoma-carcinoma sequence reflects the change of protumor/antitumor force balance, which is associated with CRC initiation and invasion.

Cancer-Associated Mutations in Normal Colorectal Mucosa Adjacent to Sporadic Neoplasia

INTRODUCTION:

Colorectal cancer arises in a multistep process of carcinogenesis from normal mucosa. The earliest precursor might be a morphologically inconspicuous precancerous field, harboring cancer-associated mutations.

METHODS:

We systematically analyzed genetic alterations in 77 tissue samples from 30 patients with sporadic colorectal neoplasms (18 large adenomas and 12 adenocarcinomas) and matched adjacent normal mucosa (N = 30), as well as normal rectal tissue (N = 17). We profiled mutations associated with colorectal cancer by targeted sequencing of 46 genetic loci using 157 custom amplicons and a median depth of 42,655 reads per loci.

RESULTS:

Multiple mutations were found in colorectal neoplasms, most frequently in APC, KRAS, and TP53. In a subgroup of 11 of 30 patients, alterations were also detected in non-neoplastic mucosa. These mutations were divergent from those in matched neoplasms. The total alteration count and the allele frequency of mutations were higher in neoplasms compared with those in adjacent tissues. We found that younger patients (≤70 years) are less likely affected by mutations in non-neoplastic mucosa than older patients (>70 years, P = 0.013), although no association was found for other variables, including type, location and differentiation of neoplasia, and previous history of polyps.

DISCUSSION:

Our data show that cancer-associated mutations can be found in non-neoplastic tissues in a subgroup of patients with colorectal neoplasms. Further studies are needed to specify the risk of occurrence and recurrence of neoplasia in this patient population.

Field carcinogenesis for risk stratification of colorectal cancer

Colorectal cancer (CRC) is characterized by genetic-environmental interplay leading to diffuse changes in the entire colonic mucosa (field carcinogenesis or field of injury) and to a pro-neoplastic genetic/epigenetic/physiological milieu. The clinical consequences are increased risk of synchronous and metachronous neoplasia. Factors such as genetics, race, ethnicity, age, and socioeconomic status are thought to influence neoplasia development. Here, we explore the potential improvement to CRC screening through exploiting field carcinogenesis, with particular focus on racial disparities and chemoprevention strategies. Also, we discuss future directions for field carcinogenesis/risk stratification using molecular and novel biophotonic techniques for personalized CRC screening.

Correlating colorectal cancer risk with field carcinogenesis progression using partial wave spectroscopic microscopy

Prior to the development of a localized cancerous tumor, diffuse molecular, and structural alterations occur throughout an organ due to genetic, environmental, and lifestyle factors. This process is known as field carcinogenesis. In this study, we used partial wave spectroscopic (PWS) microscopy to explore the progression of field carcinogenesis by measuring samples collected from 190 patients with a range of colonic history (no history, low-risk history, and high-risk history) and current colon health (healthy, nondiminutive adenomas (NDA; ≥5 mm and <10 mm), and advanced adenoma [AA; ≥10 mm, HGD, or >25% villous features]). The low-risk history groups include patients with a history of NDA. The high-risk history groups include patients with either a history of AA or colorectal cancer (CRC). PWS is a nanoscale-sensitive imaging technique which measures the organization of intracellular structure. Previous studies have shown that PWS is sensitive to changes in the higher-order (20-200 nm) chromatin topology that occur due to field carcinogenesis within histologically normal cells. The results of this study show that these nanoscale structural alterations are correlated with a patient's colonic history, which suggests that PWS can detect altered field carcinogenic signatures even in patients with negative colonoscopies. Furthermore, we developed a model to calculate the 5-year risk of developing CRC for each patient group. We found that our data fit this model remarkably well (R²  = 0.946). This correlation suggests that PWS could potentially be used to monitor CRC progression less invasively and in patients without adenomas, which opens PWS to many potential cancer care applications.

The genetics and molecular biology of colonic neoplasia: practical implications for the clinician

PURPOSE OF REVIEW

Despite the large investment of resources from screening, the fact that colorectal cancer remains the second leading cause of cancer deaths among Americans underscores the need for alternative strategies. Thus, a major clinical and research imperative is personalize clinical care, while focusing on risk stratification for screening, surveillance, chemoprevention, and therapeutic intervention.

RECENT FINDINGS

A complicating factor that colorectal cancer is biologically heterogeneous for at least four consensus molecular subtypes presents clear challenges for developing robust molecular biomarkers.

SUMMARY

The purpose of the review is to discuss the genetics and molecular biology of colonic neoplasia, high and low penetrance, and racial disparities in colonic neoplasia. Finally, we put forth the emerging concept of greater genomic landscape and the idea of chromatin protection therapy as a novel adjuvant to chemotherapy.

Field cancerisation in colorectal cancer: A new frontier or pastures past?

Despite considerable advances in our understanding of cancer biology, early diagnosis of colorectal cancer remains elusive. Based on the adenoma-carcinoma sequence, cancer develops through the progressive accumulation of mutations in key genes that regulate cell growth. However, recent mathematical modelling suggests that some of these genetic events occur prior to the development of any discernible histological abnormality. Cells acquire pro-tumourigenic mutations that are not able to produce morphological change but predispose to cancer formation. These cells can grow to form large patches of mucosa from which a cancer arises. This process has been termed “field cancerisation”. It has received little attention in the scientific literature until recently. Several studies have now demonstrated cellular, genetic and epigenetic alterations in the macroscopically normal mucosa of colorectal cancer patients. In some reports, these changes were effectively utilised to identify patients with a neoplastic lesion suggesting potential application in the clinical setting. In this article, we present the scientific evidence to support field cancerisation in colorectal cancer and discuss important limitations that require further investigation. Characterisation of the field defect is necessary to enable early diagnosis of colorectal cancer and identify molecular targets for chemoprevention. Field cancerisation offers a promising prospect for experimental cancer research and has potential to improve patient outcomes in the clinical setting.

Spatially resolved optical and ultrastructural properties of colorectal and pancreatic field carcinogenesis observed by inverse spectroscopic optical coherence tomography

Field carcinogenesis is the initial stage of cancer progression. Understanding field carcinogenesis is valuable for both cancer biology and clinical medicine. Here, we used inverse spectroscopic optical coherence tomography to study colorectal cancer (CRC) and pancreatic cancer (PC) field carcinogenesis. Depth-resolved optical and ultrastructural properties of the mucosa were quantified from histologically normal rectal biopsies from patients with and without colon adenomas (n=85) as well as from histologically normal peri-ampullary duodenal biopsies from patients with and without PC (n=22). Changes in the epithelium and stroma in CRC field carcinogenesis were separately quantified. In both compartments, optical and ultra-structural alterations were consistent. Optical alterations included lower backscattering (μb) and reduced scattering (μs') coefficients and higher anisotropy factor g. Ultrastructurally pronounced alterations were observed at length scales up to ∼450  nm, with the shape of the mass density correlation function having a higher shape factor D, thus implying a shift to larger length scales. Similar alterations were found in the PC field carcinogenesis despite the difference in genetic pathways and etiologies. We further verified that the chromatin clumping in epithelial cells and collagen cross-linking caused D to increase in vitro and could be among the mechanisms responsible for the observed changes in epithelium and stroma, respectively.

Nano-architectural alterations in mucus layer fecal colonocytes in field carcinogenesis: potential for screening

Current fecal tests (occult blood, methylation, DNA mutations) target minute amounts of tumor products among a large amount of fecal material and thus have suboptimal performance. Our group has focused on exploiting field carcinogenesis as a modality to amplify the neoplastic signal. Specifically, we have shown that endoscopically normal rectal brushings have striking nano-architectural alterations which are detectable using a novel optical technique, partial wave spectroscopic microscopy (PWS). We therefore wished to translate this approach to a fecal assay. We examined mucus layer fecal colonocytes (MLFC) at preneoplastic and neoplastic time points (confirmed with rat colonoscopy) in the azoxymethane (AOM)-treated rat model and conducted PWS analysis to derive the nano-architectural parameter, disorder strength (Ld). We confirmed these results with studies in a genetic model (the Pirc rat). We showed that MLFC appeared microscopically normal, consistent with field carcinogenesis. Ld was elevated at an early time point (5 weeks post-AOM injection, effect size = 0.40, P = 0.024) and plateaued before adenoma formation (10 weeks post-AOM, effect size = 0.66, P = 0.001), with no dramatic increase once tumors developed. We replicated these data in the preneoplastic Pirc rat with an effect size in the MLFC that replicated the rectal brushings (increase vs. age-matched controls of 62% vs. 74%, respectively). We provide the first demonstration of a biophotonics approach to fecal assay. Furthermore, targeting the nano-architectural changes of field carcinogenesis rather than the detection of tumor products may provide a novel paradigm for colorectal cancer screening.

Insights into the field carcinogenesis of ovarian cancer based on the nanocytology of endocervical and endometrial epithelial cells

Ovarian cancer ranks fifth in cancer fatalities among American women. Although curable at early stages with surgery, most women are diagnosed with symptoms of late-stage metastatic disease. Moreover, none of the current diagnostic techniques are clinically recommended for at-risk women as they preferentially target low-grade tumors (which do not affect longevity) and fail to capture early signatures of more lethal serous tumors which originate in the fimbrae region of the fallopian tubes. Hence, the early detection of ovarian cancer is challenging given the current strategy. Recently, our group has developed a novel optical imaging technique, partial wave spectroscopic (PWS) microscopy, that can quantify the nanoscale macromolecular density fluctuations within biological cells via a biomarker, disorder strength (Ld ). Using the concept of field carcinogenesis, we propose a method of detecting ovarian cancer by PWS assessment of endometrial and endocervical columnar cells. The study includes 26 patients (controls = 15, cancer = 11) for endometrium and 23 (controls = 13, cancer = 10) for endocervix. Our results highlight a significant increase in Ld (% fold-increase > 50%, p-value < 0.05) for columnar epithelial cells obtained from cancer patients compared to controls for both endocervix and endometrium. Overall, the quantification of field carcinogenic events in the endometrium and the novel observation of its extension to the cervix are unique findings in the understanding of ovarian field carcinogenesis. We further show independent validation of the presence of cervical field carcinogenesis with micro-RNA expression data.

Advances in biophotonics detection of field carcinogenesis for colon cancer risk stratification

The process of neoplastic transformation of the colon involves a progression through hyperproliferative epithelium through the aberrant crypt foci→small adenoma→large adenoma→invasive cancer→metastatic disease. These are orchestrated by sequential genetic and epigenetic events which provide the underpinnings of cellular alterations such as early induction in proliferation/suppression of apoptosis, along with the late stage increase in invasiveness. Colorectal cancer (CRC) averages 49-111 mutations per tumor encompassing 10-15 critical signaling pathways[1]. Accumulating such a high number of mutations requires a fertile mutational field, which is the hallmark of colon carcinogenesis.

While genetic susceptibility to colorectal cancer is well-known, at least half of the risk is believed to be due to exogeneous factors (e.g., obesity, diet, exercise). Understanding these risk factors represents a promising mode of tailoring screening modality and intensity. However, previous attempts using these factors (i.e., NCI risk calculator) have only been modestly successful with an area under receiver operating characteristics (ROC) curve (AUC) of just 0.61. One of the most important concepts is that risk is the interaction between these genetic and environmental components and is driven by the variety of polymorphisms. Thus, predicting risk is difficult given the complexity. On the other hand, the colonic mucosa represents the end product of the complex interplay between these multiple factors. The power of field carcinogenesis is that it reflects this interplay between genetics and environment.

Systemic folate status, rectal mucosal folate concentration and dietary intake in patients at differential risk of bowel cancer (The FAB2 Study)

BACKGROUND/OBJECTIVES

Folate has been strongly implicated in the aetiology of colorectal cancer. However, the relationship between dietary folate intake, rectal mucosal folate status and colorectal cancer risk is uncertain. The study aimed to estimate nutrient intakes and measure systemic folate status and rectal mucosal folate concentration in people at differential risk of developing colorectal cancer.

METHODS

Two hundred and twenty-eight individuals were recruited from gastroenterology clinics and subdivided into three patient groups: untreated colorectal cancer (n = 43), adenomatous polyps (n = 90) or normal bowel (n = 95). Biopsies from macroscopically normal rectal mucosa and blood were collected and used for the measurement of rectal mucosal 5-methyltetrahydrofolate (5-MeTHF) and systemic markers of folate status, respectively. Nutrient intake was estimated using a validated food frequency questionnaire.

RESULTS

Dietary intake variables, plasma 5-MeTHF and red cell folate and plasma homocysteine concentrations were similar in all three subject groups and 95% CI fell within normal range for each variable. Rectal mucosal 5-MeTHF concentration was higher in the normal mucosa of adenomatous polyp patients than in normal subjects (P = 0.055). Rectal mucosal 5-MeTHF was associated significantly with plasma folate (P < 0.001, r = 0.294), red cell folate (P = 0.014, r = 0.305), plasma homocysteine (P = 0.017, r = -0.163) and dietary folate intake (P = 0.036, r = 0.152).

CONCLUSIONS

This study demonstrates adequate folate status of patients attending gastroenterology clinics for the investigation of bowel symptoms, with no significant difference in dietary intakes or systemic folate status indices according to diagnosis. Rectal mucosal 5-MeTHF concentrations were elevated in adenomatous polyp patients, but failed to reach significance. Further studies are required to determine the biological significance of this observation.

Towards universal screening for colon cancer: a cheap, reliable, noninvasive test using gene expression analysis of rectal swabs

Though colon cancer is the second leading cause of cancer deaths in the US, it is entirely preventable through early screening to detect and remove adenomatous polyps. Colonoscopy has long been regarded as the "gold standard" but is expensive, invasive, and uncomfortable, and only about half those considered at risk for colon cancer currently submit to colonoscopy or to less reliable alternatives such as fecal occult blood test. Here we describe the use of gene expression analysis to detect altered expression of certain genes associated with not only colon cancer but also polyps. The analysis can be performed on rectal swabs, with specimens provided in a routine doctor's office visit. The existence of this cheap and simple test, together with an active program to encourage individuals to submit to screening, could help eradicate colon cancer.

Neo-angiogenesis and the premalignant micro-circulatory augmentation of early colon carcinogenesis

Spectroscopic techniques have demonstrated that in the microscopically normal mucosa, there is an increase in mucosal micro-circulation in patients harboring neoplasia elsewhere in the colon (i.e. marker of field carcinogenesis). However, the physiological and molecular basis of this early increase in blood supply (EIBS) has not been elucidated. We, therefore, investigated the microvessel density (MVD) and angiogenic gene expression in the premalignant colonic mucosa from the well-validated azoxymethane (AOM)-treated rat experimental model of colon carcinogenesis. Fisher 344 rats were treated with AOM (15 mg/kg i.p.) or saline and euthanized 14 weeks later (a time-point that precedes carcinoma development). Colon sections were studied for MVD via immunohistochemical assessment for CD31 and location was compared with optical assessment of mucosal hemoglobin with low-coherence enhanced backscattering spectroscopy (LEBS). Finally, we performed a pilot real-time PCR angiogenesis microarray (84 genes) from the microscopically normal colonic mucosa of AOM and age-matched saline treated rats. AOM treatment increased MVD in both the mucosa and submucosa of the rats (125% increase in mucosa; p<0.007, and 96% increase in submucosa; p<0.02) but the increase was most pronounced at the cryptal base consistent with the LEBS data showing maximal hemoglobin augmentation at 200-225 μm depth. Microarray analysis showed striking dysregulation of angiogenic and anti-angiogenic factors. We demonstrate, for the first time, that neo-angiogenesis occurs in the microscopically normal colonic mucosa and was accentuated at the bottom of the crypt. This finding has potential implications as a biomarker for risk-stratification and target for chemoprevention.

Light-scattering technologies for field carcinogenesis detection: a modality for endoscopic prescreening

Colonoscopy has revolutionized colorectal cancer (CRC) screening resulting in a decrease in both CRC mortality and incidence. Despite this, CRC still ranks as the second leading cause of cancer deaths among Americans underscoring the need to both increase availability and accuracy of colonoscopy. The latter considerations provide the impetus for much of the current research into adjunctive imaging technologies. Recent advances in improving detection of dysplasia that have translated into clinical practice include high-definition scopes, narrow-band imaging, and chromo-endoscopy. Another major direction of research into improving endoscopy is determining histology of lesions in situ (“optical biopsy”) with confocal endomicroscopy, fluorescence and elastic scattering spectroscopy. All these techniques are of great promise in improving delivery of endoscopy but, to date, have not addressed the potentially more important hurdle associated with logistic challenges of providing accurate CRC screening for the entire at-risk population.

Role of cytoskeleton in controlling the disorder strength of cellular nanoscale architecture

Cytoskeleton is ubiquitous throughout the cell and is involved in important cellular processes such as cellular transport, signal transduction, gene transcription, cell-division, etc. Partial wave spectroscopic microscopy is a novel optical technique that measures the statistical properties of cell nanoscale organization in terms of the disorder strength. It has been found previously that the increase in the disorder strength of cell nanoarchitecture is one of the earliest events in carcinogenesis. In this study, we investigate the cellular components responsible for the differential disorder strength between two morphologically (and hence microscopically) similar but genetically altered human colon cancer cell lines, HT29 cells and Csk shRNA-transfected HT29 cells that exhibit different degrees of neoplastic aggressiveness. To understand the role of cytoskeleton in nanoarchitectural alterations, we performed selective drug treatment on the specific cytoskeletal components of these cell types and studied the effects of cytoskeletal organization on disorder strength differences. We report that altering the cell nanoarchitecture by disrupting cytoskeletal organization leads to the attenuation of the disorder strength differences between microscopically indistinguishable HT29 and CSK constructs. We therefore demonstrate that cytoskeleton plays a role in the control of cellular nanoscale disorder.

Nanoscale cellular changes in field carcinogenesis detected by partial wave spectroscopy

Understanding alteration of cell morphology in disease has been hampered by the diffraction-limited resolution of optical microscopy (>200 nm). We recently developed an optical microscopy technique, partial wave spectroscopy (PWS), which is capable of quantifying statistical properties of cell structure at the nanoscale. Here we use PWS to show for the first time the increase in the disorder strength of the nanoscale architecture not only in tumor cells but also in the microscopically normal-appearing cells outside of the tumor. Although genetic and epigenetic alterations have been previously observed in the field of carcinogenesis, these cells were considered morphologically normal. Our data show organ-wide alteration in cell nanoarchitecture. This seems to be a general event in carcinogenesis, which is supported by our data in three types of cancer: colon, pancreatic, and lung. These results have important implications in that PWS can be used as a new method to identify patients harboring malignant or premalignant tumors by interrogating easily accessible tissue sites distant from the location of the lesion.

Rectal mucosal microvascular blood supply increase is associated with colonic neoplasia

PURPOSE

Endoscopic examination has proven effective in both detecting and preventing colorectal cancer; however, only about a quarter of eligible patients undergo screening. Even if the compliance rate increased, limited endoscopic capacity and cost would be prohibitive. There is a need for an accurate method to target colonoscopy to those most at risk of harboring colonic neoplasia. Exploiting field carcinogenesis seems to be a promising avenue. Our group recently reported that an early increase in blood supply (EIBS) is a reliable marker of field carcinogenesis in experimental models. We now investigate whether in situ detection of EIBS in the rectum can predict neoplasia elsewhere in the colon.

EXPERIMENTAL DESIGN

We developed a novel polarization-gated spectroscopy fiber-optic probe that allows depth-selective interrogation of microvascular blood content. Using the probe, we examined the blood content in vivo from the rectal mucosa of 216 patients undergoing screening colonoscopy.

RESULTS

Microvascular blood content was increased by approximately 50% in the endoscopically normal rectal mucosa of patients harboring advanced adenomas when compared with neoplasia-free patients irrespective of lesion location. Demographic factors and nonneoplastic lesions did not confound this observation. Logistic regression using mucosal oxyhemoglobin concentration and patient age resulted in a sensitivity of 83%, a specificity of 82%, and an area under the receiver operating characteristic curve of 0.88 for the detection of advanced adenomas.

CONCLUSIONS

Increased microvascular blood supply in the normal rectal mucosa is associated with the presence of clinically significant neoplasia elsewhere in the colon, supporting the development of rectal EIBS as a colon cancer risk-stratification tool.

Biomarkers correlate with colon cancer and risks: a preliminary study

PURPOSE

We previously reported that gene expression analysis of biopsies of normal-appearing large intestinal mucosa can distinguish individuals with colonic cancer and many individuals at risk for colon cancer from controls. The purpose of this study was to determine whether noninvasively removed rectal swabs can identify individuals with colon cancer or risk of colon cancer as effectively as we previously demonstrated using biopsies.

METHODS

Rectal mucosa cells were removed by rectal swabs, and their gene expression profiles were compared with those of biopsies removed by colonoscopy. Expression of 16 genes in the rectal mucosa of 12 individuals with colon cancer, 25 with polyps, 37 with family or self-reported cancer history, and 23 controls was measured by real-time reverse transcription-polymerase chain reaction.

RESULTS

We found similar results using rectal swabs and biopsies. Groups of individuals with or at risk for cancer showed an altered gene expression profile compared with controls. Moreover, each of the 12 cancer patients showed altered expression relative to the mean of controls.

CONCLUSIONS

Gene expression analysis using rectal swabs may provide a convenient way to screen for colon cancer.

TGF-alpha expression as a potential biomarker of risk within the normal-appearing colorectal mucosa of patients with and without incident sporadic adenoma

BACKGROUND

Transforming growth factor-alpha (TGF-alpha), a stimulatory growth factor and member of the epidermal growth factor family, is a mediator of oncogenesis and malignant progression in colorectal carcinogenesis. Limited evidence suggests its utility as a growth-related biomarker of risk for colorectal cancer.

METHODS

We measured expression of TGF-alpha in biopsies of normal-appearing colorectal mucosa using automated immunohistochemistry and quantitative image analysis in a subsample of 29 cases and 31 controls from a colonoscopy-based case-control study (n = 203) of biomarkers of risk for incident sporadic colorectal adenoma. Diet, lifestyle, and medical history were assessed with validated questionnaires.

RESULTS

TGF-alpha expression in the rectum was 51% higher in cases compared with controls (P = 0.05) and statistically significantly associated with accepted risk factors for colorectal neoplasms (36% lower among nonsteroidal anti-inflammatory drug users, 49% lower among women using hormone replacement therapy, 79% higher among persons with a family history of colorectal cancer).

CONCLUSIONS

TGF-alpha expression in the normal-appearing rectal mucosa shows promise as an early, potentially modifiable biomarker of risk for colorectal cancer.

Distinct changes of dendritic cell number and IL-12 mRNA level in adjacent mucosa throughout the colorectal adenoma-carcinoma sequence

Adjacent mucosa may reflect the conflicting of host factors in response to the establishment or invasion of cancers. Characterization of anti-tumor immunity in this region may add help in understanding the immune-related mechanisms of colorectal carcinoma (CRC). In this study, adjacent non-tumor mucosa from 36 patients with colorectal adenoma (CRA), 26 with CRC and normal mucosa from 15 health controls were included, immune cell populations of dendritic cell, lymphocyte and macrophage were characterized with immunohistochemistry (IHC) and tissue messenger RNA (mRNA) levels of Th1 cytokines interferon (IFN)-gamma and its upstream inducers interleukin (IL)-12 and IL-18 were quantified with real-time PCR; In addition, dendritic cell differentiation and function inhibitors cyclooxygenase-2 (COX-2) and IL-6 mRNA levels were also quantified. By IHC, a significant decreased dendritic cell density in the non-tumor mucosa adjacent to CRC was detected (P < 0.05) as compared to the normal controls or adjacent mucosa of CRA. The grading scores for lymphocyte number in the adjacent mucosa of CRA and CRC were gradually non-statistically increased, while the grading scores for macrophages number was not changed. By quantitative real-time PCR, distinct local cytokine gene expression profile was demonstrated. In which, the Th1 cytokines, particularly IL-12, were increased in adjacent mucosa of CRA, but all significantly decreased in adjacent mucosa of CRC. In addition, the mRNA levels of IL-6 and COX-2 were significantly higher in adjacent mucosa of CRC than that in adjacent mucosa of CRA (both P < 0.05). Therefore, dendritic cell functional changes could be one of the important mechanisms for altered anti-tumour immunity in the adjacent non-tumor mucosa throughout adenoma-carcinoma sequence. The increased COX-2 and IL-6 might contribute to dendritic cell functional defect in adjacent mucosa of CRC.