Suitability of circulating miRNAs as potential prognostic markers in colorectal cancer

miRNAs are crucial in cellular processes and have been shown to be abnormally expressed in cancer tissue and the circulation. Circulating miRNAs may serve as a novel class of minimally invasive biomarkers for prognosis. Within a first methodologic study, we evaluated the miRNA profile kinetics in the plasma of patients with colorectal cancer after surgical tumor removal to identify potential suitability as prognostic biomarkers. This pilot study is based on the ColoCare Study, a cohort study of newly diagnosed patients with stage I-IV colorectal cancer. Colorectal cancer pre- and postsurgical blood (2-7 days after surgery) and 6 months follow-up blood from 35 patients were examined and candidate miRNAs were investigated in the plasma. miRNA levels were measured by two-step qRT-PCR. Statistical analysis was performed using log-transformed normalized CT values using SAS 9.3. Comparing pre- and postsurgical miRNA levels revealed a statistically significant decrease of nine circulating miRNAs after surgery (miR92a, miR18a, miR320a, miR106a, miR16-2, miR20a, miR223, miR17, and miR143). Analyses of plasma levels over all three time points demonstrated a statistically significant decrease from presurgery to postsurgery and re-increase from postsurgery to the six months follow-up time point of four circulating miRNAs (miR92a, miR320a, miR106a, and miR18a). We were able to show for the first time that in plasma miRNA profiles change within days after colorectal cancer surgery. Our results underscore the role of the investigated miRNAs in colorectal cancer and their potential utility as prognostic biomarkers. See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."

Changes in urinary metabolic profiles of colorectal cancer patients enrolled in a prospective cohort study (ColoCare)

INTRODUCTION

Metabolomics is a valuable tool for biomarker screening of colorectal cancer (CRC). In this study, we profiled the urinary metabolomes of patients enrolled in a prospective patient cohort (ColoCare). We aimed to describe changes in the metabolome in the longer clinical follow-up and describe initial predictors as candidate markers with possibly prognostic significance.

METHODS

In total, 199 urine samples from CRC patients pre-surgery (n=97), 1-8 days post-surgery (n=12) and then after 6 and 12 months (n=52 and 38, respectively) were analyzed using both GC-MS and ¹H-NMR. Both datasets were analyzed separately with built in uni- and multivariate analyses of Metaboanalyst 2.0. Furthermore, adjusted linear mixed effects regression models were constructed.

RESULTS

Many concentrations of the metabolites derived from the gut microbiome were affected by CRC surgery, presumably indicating a tumor-induced shift in bacterial species. Associations of the microbial metabolites with disease stage indicate an important role of the gut microbiome in CRC.We were able to differentiate the metabolite profiles of CRC patients prior to surgery from those at any post-surgery timepoint using a multivariate model containing 20 marker metabolites (AUCROC=0.89; 95% CI:0.84-0.95).

CONCLUSION

To the best of our knowledge, this is one of the first metabolomic studies to follow CRC patients in a prospective setting with repeated urine sampling over time. We were able to confirm markers initially identified in case-control studies and pin point metabolites which may serve as candidates for prognostic biomarkers of CRC.

Tumor-infiltrating lymphocytes in colorectal tumors display a diversity of T cell receptor sequences that differ from the T cells in adjacent mucosal tissue

Tumors from colorectal cancer (CRC) are generally immunogenic and commonly infiltrated with T lymphocytes. However, the details of the adaptive immune reaction to these tumors are poorly understood. We have accrued both colon tumor samples and adjacent healthy mucosal samples from 15 CRC patients to study lymphocytes infiltrating these tissues. We apply a method for detailed sequencing of T-cell receptor (TCR) sequences from tumor-infiltrating lymphocytes (TILs) in CRC tumors at high throughput to probe T-cell clones in comparison with the TCRs from adjacent healthy mucosal tissue. In parallel, we captured TIL counts using standard immunohistochemistry. The variation in diversity of the TIL repertoire was far wider than the variation of T-cell clones in the healthy mucosa, and the oligoclonality was higher on average in the tumors. However, the diversity of the T-cell repertoire in both CRC tumors and healthy mucosa was on average 100-fold lower than in peripheral blood. Using the TCR sequences to identify and track clones between mucosal and tumor samples, we determined that the immune response in the tumor is different than in the adjacent mucosal tissue, and the number of shared clones is not dependent on distance between the samples. Together, these data imply that CRC tumors induce a specific adaptive immune response, but that this response differs widely in strength and breadth between patients.

Abstract B11: Level of circulating miRNAs in patients before and after surgical removal of colorectal tumors: A pilot study

Introduction: MicroRNAs (miRNAs) are small, noncoding RNAs that function as regulators of many critical cellular processes, are known to be abnormally expressed in cancer, and play a role either by oncogenic or tumor-suppressor function. miRNA expression differs between normal and tumor tissue and varies among tissue types. Upregulated miRNAs in tumor tissue can also be detected in the blood circulation and are emerging as promising biomarkers. So far, little is known about how rapid changes, i.e. surgical removal of a colorectal tumor, will be reflected by changing miRNA level in the circulation. Thus, within this pilot study we aim to characterize the level of circulating miRNA prior to and after surgical removal of a colorectal tumor.

Methods: The investigations are based on the ColoCare Study, an ongoing cohort study of colorectal cancer patients (stage I-IV). Newly-diagnosed colorectal cancer patients are recruited at the ColoCare study site in Heidelberg, Germany prior to surgery for tumor resection. For this pilot study, pre- and post-surgical blood (4.1 (2-9) days after surgery) from n=31 patients was examined. Plasma was obtained by centrifugation (2,500 x g) and stored at -80°C upon isolation of miRNA using the Qiagen miRNeasy Mini Kit. We selected 17 candidate miRNAs which have been previously noted to be altered in the circulation of colorectal cancer patients. miRNA levels (n=17) were measured by qRT-PCR using Taqman miRNA reverse transcription kits with miRNA-specific stem-loop primers and Taqman MicroRNA Assays. Data were normalized by subtracting the CT value of the spike-in control (cel-miR-39) from the target miRNA's CT value and miRNA expression is presented as 2−ΔCT transformed values. Statistical analysis was performed using log-transformed normalized CT values using PROC GLM (SAS 9.2).

Results: Study participants were on average 61 years old (35-79), 10 of the participants were diagnosed with colon and 21 with rectal cancer. Ten patients had later stage disease (stages III or IV).

Comparing pre- and post-surgical miRNA levels, revealed a statistically significant decrease of 7 circulating miRNAs (miR-106a: p=0.002, miR-16: p=0.02, miR-18a: p=0.004, miR20a: p=0.01, miR223: p=0.04, miR-320: p=0.006, miR-92: p=0.0008). The remaining candidate miRNAs did not change significantly between the time points.

Conclusion: Although the sample size of this pilot study is small, we observed a substantial decrease of 7 target miRNAs approximately one week after surgical tumor removal. Our results underscore the role of these miRNAs in colorectal carcinogenesis. As next steps, we will continue characterizing the changes in plasma level of the described miRNAs for subsequent post-surgical follow-up time points.

Citation Format: Nina Habermann, Jonas Ristau, Katharina Buck, Jürgen Staffa, Petra Schrotz-King, Dominique Scherer, Stephanie Tosic, Verena Widmer, Clare Abbenhardt, Karen W. Makar, Barbara Burwinkel, Cornelia M. Ulrich. Level of circulating miRNAs in patients before and after surgical removal of colorectal tumors: A pilot study. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr B11.

Abstract 79: The relationship between abdominal fat distribution, vitamin D levels, and physical activity in colorectal cancer patients: A pilot study

Introduction: Abdominal obesity, low physical activity and low levels of Vitamin D (Vit D) are associated with an increased risk for colorectal cancer (CRC). Physical inactivity contributes to obesity – an emerging global health burden. Individuals with the same body mass index (BMI) may vary in the distribution of subcutaneous and visceral abdominal fat. Subcutaneous and visceral fat differ in their metabolic functions. Moreover, Vit D is metabolized in adipose tissue; however, it is unclear if Vit D levels are influenced by the amount and the distribution of adipose tissue. Decreased levels of Vit D are found in obese subjects and a positive association between physical activity and Vit D levels is currently discussed. It is still unknown how this triangle relationship is displayed in CRC patients and how it might influence the course of disease. Thus, within this pilot study we explored the relationship between abdominal fat distribution, plasma levels of Vit D, and metabolic equivalent of task (MET) level as a marker for intensity and energy expenditure of physical activity in CRC patients.

Methods: This pilot study was conducted on 194 CRC patients from the ColoCare Study, a cohort of newly-diagnosed stage I-IV CRC patients (age>18). Plasma 25(OH)VitD3 levels were measured by LC/MSD. BMI was calculated (kg/m2) and the absolute abdominal fat and the distribution of subcutaneous and visceral abdominal fat was assessed by abdominal computed tomography (CT) scans. The total (TFA), subcutaneous (SFA) and visceral fat area (VFA) is presented as an area (cm2) on level L3/L4. To assess physical activity we calculated the individual MET h/week from questionnaire data (based on the VITAL study questionnaire, FHCRC, Seattle). Spearman correlation analysis was used to assess the relationship between abdominal fat distribution, Vit D levels (adjusted for season), and METs. Moreover, subgroup analyses in male subjects were performed whereas sample size was too small for further subgrouping.

Results: Study participants were on average 62 years old and diagnosed with either colon (44%), rectal (50%) or rectosigmoid (6%) primary cancer. Data were available on n=186 (BMI), n=118 (CT scans), n=133 (Vit D) and n=96 (MET) subjects based on sequential implementation of assessments. Only correlations with at least 40 individuals are reported. Our evaluation suggests a negative association between Vit D and VFA (r=-0.14, p=0.20). However, no association was found for BMI with Vit D and MET levels, respectively. MET levels were negatively correlated with VFA/SFA ratio (r=-0.22, p=0.13). In male patients MET levels were positively correlated with SFA (r=0.27, p=0.08) and negatively correlated with VFA/SFA ratio (r=-0.41, p<0.01).

Conclusion: Our pilot data suggest that an increased portion of visceral but not subcutaneous fat may be linked to lower levels of Vit D. Furthermore, higher MET levels may be associated with a higher visceral/subcutaneous fat ratio and might influence Vit D levels by changes in abdominal fat distribution. Additional data collection is underway and will be presented.

Citation Format: Jürgen Staffa, Johanna Welzel, Katharina Buck, Hanna Högenauer, Petra Schrotz-King, Nina Habermann, Dominique Scherer, Stephanie Tosic, Verena Widmer, Clare Abbenhardt, Gerd Würtele, Robert Owen, Michael Hoffmeister, Hermann Brenner, Jenny Chang-Claude, Hans-U. Kauczor, Cornelia M. Ulrich. The relationship between abdominal fat distribution, vitamin D levels, and physical activity in colorectal cancer patients: A pilot study. [abstract]. In: Proceedings of the AACR Special Conference on Post-GWAS Horizons in Molecular Epidemiology: Digging Deeper into the Environment; 2012 Nov 11-14; Hollywood, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(11 Suppl):Abstract nr 79.

Abstract 81: Dietary supplement use among German colorectal cancer patients: The ColoCare Study

Introduction: Colorectal cancer (CRC) is the second most common type of cancer in the United States and Europe and a leading cause of cancer death in the Western world. Except for age and inherited syndromes, risk factors are mainly lifestyle-related, including diets high in red meat, lack of physical activity, obesity, or smoking. These factors may also affect clinical outcomes among colorectal cancer patients. One potentially relevant health behavior is use of nutritional supplements. The effects of supplement use after diagnosis, and particularly during chemotherapy are unknown, while their use, particularly in the United States, is high.

Objective: To analyze preliminary trends of supplement use over time in CRC patients enrolled at the German study site (Heidelberg) of the international ColoCare Consortium.

Methods: The intake of dietary supplements was assessed among 83 patients recruited from 2010-2012 in the ongoing prospective patient cohort study ColoCare. Data on supplement use, including frequency, duration, dose per day, and type, was obtained by questionnaire. At diagnosis we assessed information regarding supplement use two years prior to diagnosis (TP1) and one month prior to diagnosis (TP2); six months later, we assessed use between TP2 and the six month timepoint (TP3) and at six months (TP4). Demographic and clinical data were obtained by questionnaires and clinical chart abstraction. The distributions of supplement users and non-users with respect to demographic, clinical, and lifestyle factors were assessed using frequency tables and Fisher's exact tests.

Results: In total 33 different supplements were reported, most commonly vitamin use. A tendency towards increased supplement intake after diagnosis was observed. The intake was highest after diagnosis (TP3: 36.1%) compared to prior to diagnosis (TP1: 26.5%) and at six months (TP4:27.7%). Investigation of potential predictors of supplement use, including demographic (sex, age), clinical (tumor stage), and lifestyle characteristics (smoking, income, education) did not show any difference; when supplement use status was categorized by BMI a significant difference was observed at TP2 (p<0.01).

Conclusion: Among German CRC patients, supplement use was highest shortly after diagnosis, and potentially BMI dependent. This increase in supplement use may be important with respect to cancer therapy and potential drug interactions. Continued surveillance through the ColoCare study will investigate the role of supplements in recurrence of disease, and thus support the development of clinical guidelines for supplement use among cancer patients.

Citation Format: Petra Schrotz-King, Kira Dölp, Michael Paskow, Katharina Buck, Clare Abbenhardt, Jürgen Staffa, Stephanie Tosic, Verena Widmer, Dominique Scherer, Nina Habermann, Kathy Vickers, Rachel E. Wilbur, Michael Hoffmeister, Jenny Chang-Claude, Hermann Brenner, Cornelia M. Ulrich. Dietary supplement use among German colorectal cancer patients: The ColoCare Study. [abstract]. In: Proceedings of the AACR Special Conference on Post-GWAS Horizons in Molecular Epidemiology: Digging Deeper into the Environment; 2012 Nov 11-14; Hollywood, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(11 Suppl):Abstract nr 81.

Familial risk of migraine: a population-based study

Estimates of familial aggregation of migraine have varied considerably due, in part, to methodological differences among studies. We concluded a population-based study of 73 clinically confirmed probands with migraine, 72 matched control probands, and 511 of their first-degree relatives, all of whom were directly interviewed. The risk of migraine was 50% more likely in relatives of migraine probands than in relatives of controls. Migraine risk was considerably higher among relatives of probands with disabling migraine compared with relatives of probands with minimal disability. Moreover, for probands with minimal disability, no excess risk of migraine in female relatives was observed. Finally, in relatives of male migraine probands, there appears to be an excess risk of migraine with aura. A borderline significant relative risk of 4.04 was observed. No excess risk was observed among relatives of male probands who had migraine without aura. This study suggests that familial factors (environment related to the family or genetic factors) account for less than one-half of all migraine cases in the population. Degree of disability in the proband appears to influence familial risk. These results suggest that the development of migraine is determined by complex genetic as well as environmental factors.

Sensitivity study in vivo: glass-ionomer versus zinc-phosphate bases beneath amalgam restorations

This study in vivo evaluated the sensitivity of class 1 and 2 amalgam restorations which had bases of either zinc phosphate or an admix, silver-reinforced glass ionomer. The evaluation of sensitivity was done by providing the patient with five postcard questionnaires to be mailed to the clinic over a period of time from one to 28 days. Teeth restored with amalgam and silver-reinforced glass ionomer were significantly less sensitive to cold than those restored with amalgam and zinc phosphate.