Dysregulation of microRNAs in colonic field carcinogenesis: implications for screening

Aloperine inhibits colorectal cancer cell proliferation and metastasis progress via regulating miR-296-5p/STAT3 axis

Anti-tumorous effect of Aloperine (ALO) has been previously found. This study examined the role and the underlying mechanism of ALO in colorectal cancer (CRC). CRC cells were processed by different concentrations of ALO, and subsequently the cell proliferation was detected by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and miR-296-5p expression was determined by quantitative real-time polymerase chain reaction (qRT-PCR). Moreover, the target gene of miR-296-5p was predicted by TargetScan and confirmed by dual-luciferase reporter assay. The expressions of signal transducer and activator of transcription 3 (STAT3), apoptosis-related proteins and epithelial-mesenchymal transition (EMT)-related markers were measured by Western blot. Clone formation assay, flow cytometry, wound-healing and Transwell assays were respectively employed to detect cell proliferation, apoptosis, migration and invasion. ALO inhibited CRC cell proliferation in a dose-dependent manner. MiR-296-5p was low-expressed in CRC tissues and cells, and ALO promoted miR-296-5p expression. STAT3 was targeted by miR-296-5p. Up-regulation of miR-296-5p and ALO treatment both suppressed STAT3 expression, inhibited CRC cell proliferation, migration, invasion as well as the expressions of Bcl-2 and N-cadherin, but promoted apoptosis and expressions of Bax and E-cadherin, which were all reversed by overexpressed STAT3. ALO inhibited CRC cell proliferation, metastasis and EMT but promoted apoptosis via regulating miR-296-5p/STAT3 axis.

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.

Diagnostic Value of Combining miRNAs, CEA Measurement and the FOBT in Colorectal Cancer Screening

Introduction

Colorectal cancer (CRC) is one of the most common illnesses that seriously threatens human health; many papers have reported that microRNAs (miRNAs) are promising biomarkers for cancer detection. However, miRNAs have not been used in clinical practice even though they are superior to the currently used screening tools, such as the fecal occult blood test (FOBT) and carcinoembryonic antigen (CEA) measurement.

Methods

In this study, we focused on the usefulness of a panel of miRNAs and the combination of miRNAs with the FOBT and CEA measurement, the currently used general diagnosis methods, to improve the accuracy of CRC diagnosis.

Results

The results showed that the miRNA panel has great potential value as a diagnostic biomarker with high specificity and sensitivity, and further analysis demonstrated that the miRNA panel had higher sensitivity and specificity than the FOBT and CEA measurement, even when these methods were combined. More importantly, although the miRNA panel is superior to the FOBT and CEA measurement, it cannot replace them.

Conclusions

In this research, we investigated whether complementarity exists between the miRNA panel and the FOBT and CEA measurement for CRC diagnosis. Interestingly, the results indicated that the FOBT and CEA measurement could improve the positivity rate of the miRNA panel as a biomarker and vice versa.

Biomimicking Fiber Scaffold as an Effective In Vitro and In Vivo MicroRNA Screening Platform for Directing Tissue Regeneration

MicroRNAs effectively modulate protein expression and cellular response. Unfortunately, the lack of robust nonviral delivery platforms has limited the therapeutic application of microRNAs. Additionally, there is a shortage of drug-screening platforms that are directly translatable from in vitro to in vivo. Here, a fiber substrate that provides nonviral delivery of microRNAs for in vitro and in vivo microRNA screening is introduced. As a proof of concept, difficult-to-transfect primary neurons are targeted and the efficacy of this system is evaluated in a rat spinal cord injury model. With this platform, enhanced gene-silencing is achieved in neurons as compared to conventional bolus delivery (p < 0.05). Thereafter, four well-recognized microRNAs (miR-21, miR-222, miR-132, and miR-431) and their cocktails are screened systematically. Regardless of age and origin of the neurons, similar trends are observed. Next, this fiber substrate is translated into a 3D system for direct in vivo microRNA screening. Robust nerve ingrowth is observed as early as two weeks after scaffold implantation. Nerve regeneration in response to the microRNA cocktails is similar to in vitro experiments. Altogether, the potential of the fiber platform is demonstrated in providing effective microRNA screening and direct translation into in vivo applications.

High-Amylose Maize, Potato, and Butyrylated Starch Modulate Large Intestinal Fermentation, Microbial Composition, and Oncogenic miRNA Expression in Rats Fed A High-Protein Meat Diet

High red meat intake is associated with the risk of colorectal cancer (CRC), whereas dietary fibers, such as resistant starch (RS) seemed to protect against CRC. The aim of this study was to determine whether high-amylose potato starch (HAPS), high-amylose maize starch (HAMS), and butyrylated high-amylose maize starch (HAMSB)—produced by an organocatalytic route—could oppose the negative effects of a high-protein meat diet (HPM), in terms of fermentation pattern, cecal microbial composition, and colonic biomarkers of CRC. Rats were fed a HPM diet or an HPM diet where 10% of the maize starch was substituted with either HAPS, HAMS, or HAMSB, for 4 weeks. Feces, cecum digesta, and colonic tissue were obtained for biochemical, microbial, gene expression (oncogenic microRNA), and immuno-histochemical (O⁶-methyl-2-deoxyguanosine (O⁶MeG) adduct) analysis. The HAMS and HAMSB diets shifted the fecal fermentation pattern from protein towards carbohydrate metabolism. The HAMSB diet also substantially increased fecal butyrate concentration and the pool, compared with the other diets. All three RS treatments altered the cecal microbial composition in a diet specific manner. HAPS and HAMSB showed CRC preventive effects, based on the reduced colonic oncogenic miR17-92 cluster miRNA expression, but there was no significant diet-induced differences in the colonic O⁶MeG adduct levels. Overall, HAMSB consumption showed the most potential for limiting the negative effects of a high-meat diet.

Up-regulation of microRNA-19b is associated with metastasis and predicts poor prognosis in patients with colorectal cancer

Recent evidence has demonstrated that microRNA-19b (miR-19b) is elevated and functions as a prognosis predictor in hepatocellular carcinoma and melanoma. However, its expression and clinical significance in colorectal cancer (CRC) remain unclear. The study aimed to identify the correlation between miR-19b expression and the clinicopathological features and prognosis of patients with CRC. In this study, we found that the levels of miR-19b were significantly up-regulated in CRC tissues and cell lines compared with matched adjacent non-cancerous tissues and human colon mucosal epithelial cell lines, and its expression was also increased in patients with lymph node metastasis compared with those patients with no lymph node metastasis. Meanwhile, the patients with distal metastasis have a higher miR-19b expression than those patients with no distal metastasis. The high expression of miR-19b in patients with CRC was associated with lymph node metastasis and distant metastasis. miR-19b expression was an independent prognostic indicator for overall survival of CRC patients. Moreover, patients with a high miR-19b expression have shorter overall survival times than those patients with a low miR-19b expression. In addition, an in vitro functional assay showed that miR-19b knockdown restrained the migration and invasion of HCT116 and SW480 cells. In summary, the study provides the first convincing statistical and experimental evidence that the up-regulation of miR-19b is associated with metastasis and predicts unfavorable prognosis in patients with CRC, suggesting that miR-19b may serve as a novel and promising prognostic biomarker in CRC.

Single Nucleotide Polymorphism Facilitated Down-Regulation of the Cohesin Stromal Antigen-1: Implications for Colorectal Cancer Racial Disparities

The biological underpinnings for racial disparities in colorectal cancer (CRC) incidence remain to be elucidated. We have previously reported that the cohesin SA-1 down-regulation is an early event in colon carcinogenesis which is dramatically accentuated in African-Americans. In order to investigate the mechanism, we evaluated single nucleotide polymorphisms (SNPs) for association with SA-1-related outcomes followed by gene editing of candidate SNP. We observed that rs34149860 SNP was significantly associated with a lower colonic mucosal SA-1 expression and evaluation of public databases showed striking racial discordance. Given that the predicted SNP would alter miR-29b binding site, we used CRISPR knock-in in CRC cells and demonstrated that the SNP but not wild-type had profound alterations in SA-1 expression with miR-29b inhibitor. This is the first demonstration of high-order chromatin regulators as a modulator of racial differences, risk alteration with SNPs and finally specific modulation by microRNAs.

SuperQuant-assisted comparative proteome analysis of glioblastoma subpopulations allows for identification of potential novel therapeutic targets and cell markers

Glioblastoma (GBM) is a highly aggressive brain cancer with poor prognosis and low survival rate. Invasive cancer stem-like cells (CSCs) are responsible for tumor recurrence because they escape current treatments. Our main goal was to study the proteome of three GBM subpopulations to identify key molecules behind GBM cell phenotypes and potential cell markers for migrating cells. We used SuperQuant-an enhanced quantitative proteome approach-to increase proteome coverage. We found 148 proteins differentially regulated in migrating CSCs and 199 proteins differentially regulated in differentiated cells. We used Ingenuity Pathway Analysis (IPA) to predict upstream regulators, downstream effects and canonical pathways associated with regulated proteins. IPA analysis predicted activation of integrin-linked kinase (ILK) signaling, actin cytoskeleton signaling, and lysine demethylase 5B (KDM5B) in CSC migration. Moreover, our data suggested that microRNA-122 (miR-122) is a potential upstream regulator of GBM phenotypes as miR-122 activation was predicted for differentiated cells while its inhibition was predicted for migrating CSCs. Finally, we validated transferrin (TF) and procollagen-lysine 2-oxoglutarate 5-dioxygenase 2 (PLOD2) as potential markers for migrating cells.

A Highly Predictive Model for Diagnosis of Colorectal Neoplasms Using Plasma MicroRNA: Improving Specificity and Sensitivity

OBJECTIVE

To develop a plasma-based microRNA (miRNA) diagnostic assay specific for colorectal neoplasms, building upon our prior work.

BACKGROUND

Colorectal neoplasms [colorectal cancer (CRC) and colorectal advanced adenoma (CAA)] frequently develop in individuals at ages when other common cancers also occur. Current screening methods lack sensitivity, specificity, and have poor patient compliance.

METHODS

Plasma was screened for 380 miRNAs using microfluidic array technology from a "Training" cohort of 60 patients, (10 each) control, CRC, CAA, breast cancer, pancreatic cancer, and lung cancer. We identified uniquely dysregulated miRNAs specific for colorectal neoplasia (P < 0.05, false discovery rate: 5%, adjusted α = 0.0038). These miRNAs were evaluated using single assays in a "Test" cohort of 120 patients. A mathematical model was developed to predict blinded sample identity in a 150 patient "Validation" cohort using repeat-sub-sampling validation of the testing dataset with 1000 iterations each to assess model detection accuracy.

RESULTS

Seven miRNAs (miR-21, miR-29c, miR-122, miR-192, miR-346, miR-372, and miR-374a) were selected based upon P value, area under the curve (AUC), fold change, and biological plausibility. Area under the curve (±95% confidence interval) for "Test" cohort comparisons were 0.91 (0.85-0.96) between all neoplasia and controls, 0.79 (0.70-0.88) between colorectal neoplasia and other cancers, and 0.98 (0.96-1.0) between CRC and colorectal adenomas. In our "Validation" cohort, our mathematical model predicted blinded sample identity with 69% to 77% accuracy, 67% to 76% accuracy, and 86% to 90% accuracy for each comparison, respectively.

CONCLUSIONS

Our plasma miRNA assay and prediction model differentiate colorectal neoplasia from patients with other neoplasms and from controls with higher sensitivity and specificity compared with current clinical standards.

Combined miRNA profiling and proteomics demonstrates that different miRNAs target a common set of proteins to promote colorectal cancer metastasis

The process of liver colonization in colorectal cancer remains poorly characterized. Here, we addressed the role of microRNA (miRNA) dysregulation in metastasis. We first compared miRNA expression profiles between colorectal cancer cell lines with different metastatic properties and then identified target proteins of the dysregulated miRNAs to establish their functions and prognostic value. We found that 38 miRNAs were differentially expressed between highly metastatic (KM12SM/SW620) and poorly metastatic (KM12C/SW480) cancer cell lines. After initial validation, we determined that three miRNAs (miR-424-3p, -503, and -1292) were overexpressed in metastatic colorectal cancer cell lines and human samples. Stable transduction of non-metastatic cells with each of the three miRNAs promoted metastatic properties in culture and increased liver colonization in vivo. Moreover, miR-424-3p and miR-1292 were associated with poor prognosis in human patients. A quantitative proteomic analysis of colorectal cancer cells transfected with miR-424-3p, miR-503, or miR-1292 identified alterations in 149, 129, or 121 proteins, respectively, with an extensive overlap of the target proteins of the three miRNAs. Importantly, down-regulation of two of these shared target proteins, CKB and UBA2, increased cell adhesion and proliferation in colorectal cancer cells. The capacity of distinct miRNAs to regulate the same mRNAs boosts the capacity of miRNAs to regulate cancer metastasis and underscores the necessity of targeting multiple miRNAs for effective cancer therapy. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

miR-296 inhibits the metastasis and epithelial-mesenchymal transition of colorectal cancer by targeting S100A4

Background

Dysregulation of microRNAs (miRNAs) is actively involved in the pathogenesis and tumorigenicity of colorectal cancer (CRC). miR-296 was found to play either oncogenic or tumor suppressive role in human cancers. However, the status of miR-296 and its function in CRC remain unknown.

Methods

The expression of miR-296 was confirmed by qRT-PCR in CRC tissues and cells, and its level was altered by corresponding miRNA vectors. Wound healing and Transwall assays were performed to detect the migration and invasion of CRC cells. The levels of proteins were measured using immunoblotting, immunohistochemistry and immunofluorescence.

Results

Underexpression of miR-296 was disclosed in CRC tissues and cells. Its decreased level was evidently correlated with adverse clinical parameters and poor prognosis of CRC patients. In vitro experiments indicated that miR-296 inhibited CRC cell migration and invasion. Mechanically, miR-296 inhibited the epithelial-mesenchymal transition (EMT) of CRC cells. A negative correlation between miR-296 and S100A4 expression was observed in CRC tissues. Luciferase reporter assays indicated that miR-296 inversely regulated the luciferase activity of 3’-UTR of S100A4. Herein, S100A4 was found to be a downstream molecule of miR-296 in CRC. Furthermore, S100A4 mediated the anti-metastatic effects of miR-296 on EMT, migration and invasion of CRC cells.

Conclusions

miR-296 functions as an anti-metastatic factor mainly by suppressing S100A4 in CRC. It potentially acts as a prognostic predictor and a drug-target for CRC patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3121-z) contains supplementary material, which is available to authorized users.

Spectral biomarkers for chemoprevention of colonic neoplasia: a placebo-controlled double-blinded trial with aspirin

OBJECTIVE

A major impediment to translating chemoprevention to clinical practice has been lack of intermediate biomarkers. We previously reported that rectal interrogation with low-coherence enhanced backscattering spectroscopy (LEBS) detected microarchitectural manifestations of field carcinogenesis. We now wanted to ascertain if reversion of two LEBS markers spectral slope (SPEC) and fractal dimension (FRAC) could serve as a marker for chemopreventive efficacy.

DESIGN

We conducted a multicentre, prospective, randomised, double-blind placebo-controlled, clinical trial in subjects with a history of colonic neoplasia who manifested altered SPEC/FRAC in histologically normal colonic mucosa. Subjects (n=79) were randomised to 325 mg aspirin or placebo. The primary endpoint changed in FRAC and SPEC spectral markers after 3 months. Mucosal levels of prostaglandin E2 (PGE2) and UDP-glucuronosyltransferase (UGT)1A6 genotypes were planned secondary endpoints.

RESULTS

At 3 months, the aspirin group manifested alterations in SPEC (48.9%, p=0.055) and FRAC (55.4%, p=0.200) with the direction towards non-neoplastic status. As a measure of aspirin's pharmacological efficacy, we assessed changes in rectal PGE2 levels and noted that it correlated with SPEC and FRAC alterations (R=-0.55, p=0.01 and R=0.57, p=0.009, respectively) whereas there was no significant correlation in placebo specimens. While UGT1A6 subgroup analysis did not achieve statistical significance, the changes in SPEC and FRAC to a less neoplastic direction occurred only in the variant consonant with epidemiological evidence of chemoprevention.

CONCLUSIONS

We provide the first proof of concept, albeit somewhat underpowered, that spectral markers reversion mirrors antineoplastic efficacy providing a potential modality for titration of agent type/dose to optimise chemopreventive strategies in clinical practice.

TRIAL NUMBER

NCT00468910.

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.

The Role of Epigenomics in the Study of Cancer Biomarkers and in the Development of Diagnostic Tools

Epigenetics plays a key role in cancer development. Genetics alone cannot explain sporadic cancer and cancer development in individuals with no family history or a weak family history of cancer. Epigenetics provides a mechanism to explain the development of cancer in such situations. Alterations in epigenetic profiling may provide important insights into the etiology and natural history of cancer. Because several epigenetic changes occur before histopathological changes, they can serve as biomarkers for cancer diagnosis and risk assessment. Many cancers may remain asymptomatic until relatively late stages; in managing the disease, efforts should be focused on early detection, accurate prediction of disease progression, and frequent monitoring. This chapter describes epigenetic biomarkers as they are expressed during cancer development and their potential use in cancer diagnosis and prognosis. Based on epigenomic information, biomarkers have been identified that may serve as diagnostic tools; some such biomarkers also may be useful in identifying individuals who will respond to therapy and survive longer. The importance of analytical and clinical validation of biomarkers is discussed, along with challenges and opportunities in this field.

Expression and clinical significance of microRNA-376a in colorectal cancer

The incidence of colorectal cancer (CRC) is increasing in many Asian countries and microRNAs have already been proven to be associated with tumorigenesis. Currently, microRNA-376a (miR-376a) expression and association with clinical factors in CRC remains unclear. In this study, real-time quantitative reverse transcriptase- polymerase chain reaction (qRT-PCR) was carried out on 53 matched pairs of CRC and adjacent normal mucosa to investigate the expression levels of miR-376a. According to the high or low expression of miR-376a, patients were divided into two groups. The relationship between miR-376a expression and clinicopathological factors of 53 patients was evaluated. Survival analysis of 53 CRC patients was performed with clinical follow- up information and survival curves were assessed by the Kaplan-Meier method. Immunohistochemistry (IHC) staining was performed on sections of paraffin-embedded tissue to investigate the vascular endothelial growth factor (VEGF) expression. MiR-376a showed low expression in cancer tissues compared to the adjacent normal tissues and altered high miR-376a expression tended to be positively correlated with advanced lymph node metastasis and shorter patient survival. VEGF IHC positivity was significantly more common in patients with high expression levels of miR-376a.Those results demonstrated that miR-376a may be a meaningful prognostic biomarker and potential therapeutic target in colorectal cancer.

Identification and validation of potential biomarkers for the detection of dysregulated microRNA by qPCR in patients with colorectal adenocarcinoma

Colorectal cancer represents a lethal disease that has raised concern and has attracted significant attention. Adenocarcinoma is the most common type of colorectal cancer (CRC). MicroRNAs are thought to be potential biomarkers of CRC. Many researchers have focused on the expression pattern of miRNAs in CRC. However, previous studies did not pay particular attention to the effects of the degree of differentiation of the cancer with respect to the miRNA expression profile. First, this study compared the expression level of 1547 miRNAs by qRT-PCR in Colorectal adenocarcinoma tissues to that in paired normal tissues. In all, 93 miRNAs were identified that were significantly dysregulated in Colorectal adenocarcinoma relative to normal tissues (P<0.05). Then, we analyzed their potential as cancer biomarkers by ROC analysis, and the result revealed that three miRNAs with high sensitivity and specificity are suitable as biomarkers for the diagnosis of CRC (the value of the AUC was greater than 0.7). Interestingly, previous reports of 23 of these miRNAs have been scarce. Furthermore, we wanted to analyze the difference between well- and moderately differentiated cancers, and as expected, 58 miRNAs showed significant dysregulation. Importantly, 32 miRNAs were able to not only distinguish cancer tissues from normal tissues, but they were also able to identify well- and moderately differentiated cancers. In conclusion, the degree of differentiation has an important influence on the miRNA expression pattern. To avoid misdiagnoses and missed diagnoses, tumors of different degrees of differentiation should be treated differently when miRNAs are used as cancer biomarkers.

Etiologic field effect: reappraisal of the field effect concept in cancer predisposition and progression

The term 'field effect' (also known as field defect, field cancerization, or field carcinogenesis) has been used to describe a field of cellular and molecular alteration, which predisposes to the development of neoplasms within that territory. We explore an expanded, integrative concept, 'etiologic field effect', which asserts that various etiologic factors (the exposome including dietary, lifestyle, environmental, microbial, hormonal, and genetic factors) and their interactions (the interactome) contribute to a tissue microenvironmental milieu that constitutes a 'field of susceptibility' to neoplasia initiation, evolution, and progression. Importantly, etiological fields predate the acquisition of molecular aberrations commonly considered to indicate presence of filed effect. Inspired by molecular pathological epidemiology (MPE) research, which examines the influence of etiologic factors on cellular and molecular alterations during disease course, an etiologically focused approach to field effect can: (1) broaden the horizons of our inquiry into cancer susceptibility and progression at molecular, cellular, and environmental levels, during all stages of tumor evolution; (2) embrace host-environment-tumor interactions (including gene-environment interactions) occurring in the tumor microenvironment; and, (3) help explain intriguing observations, such as shared molecular features between bilateral primary breast carcinomas, and between synchronous colorectal cancers, where similar molecular changes are absent from intervening normal colon. MPE research has identified a number of endogenous and environmental exposures which can influence not only molecular signatures in the genome, epigenome, transcriptome, proteome, metabolome and interactome, but also host immunity and tumor behavior. We anticipate that future technological advances will allow the development of in vivo biosensors capable of detecting and quantifying 'etiologic field effect' as abnormal network pathology patterns of cellular and microenvironmental responses to endogenous and exogenous exposures. Through an 'etiologic field effect' paradigm, and holistic systems pathology (systems biology) approaches to cancer biology, we can improve personalized prevention and treatment strategies for precision medicine.

MicroRNA-410 suppresses migration and invasion by targeting MDM2 in gastric cancer

Gastric cancer is one of the most frequent malignancies in tumors in the East Asian countries. Identifying precise prognostic markers and effective therapeutic targets is important in the treatment of gastric cancer. microRNAs (miRNAs) play important roles in tumorigenesis. However, the mechanisms by which miRNAs regulate gastric cancer metastasis remain poorly understood. In this study, we found that the levels of miR-410 in gastric cancer and cell lines were much lower than that in the normal control, respectively, and the lower level of miR-410 was significantly associated with lymph-node metastasis. Transfection of miR-410 mimics could significantly inhibit the cell proliferation, migration and invasion in the HGC-27 gastric cancer cell lines. In contrast, knockdown of miR-410 had the opposite effect on the cell proliferation, migration and invasion. Moreover, we also found that MDM2 was negatively regulated by miR-410 at the post-transcriptional level, via a specific target site with the 3′UTR by luciferase reporter assay. The expression of MDM2 was inversely correlated with miR-410 expression in gastric cancer tissues, and overexpression of MDM2 in miR-410-transfected gastric cancer cells effectively rescued the inhibition of cell proliferation and invasion caused by miR-410. Thus, our findings suggested that miR-410 acted as a new tumor suppressor by targeting the MDM2 gene and inhibiting gastric cancer cells proliferation, migration and invasion. The findings of this study contributed to the current understanding of these functions of miR-410 in gastric cancer.

Buccal microRNA dysregulation in lung field carcinogenesis: gender-specific implications

MicroRNAs (miRNAs) have been shown to be reliable early biomarkers in a variety of cancers including that of lung. We ascertained whether the biomarker potential of miRNAs could be validated in microscopically normal and easily accessible buccal epithelial brushings from cigarette smokers as a consequence of lung cancer linked ‘field carcinogenesis’. We found that compared to neoplasia-free subjects, a panel of 68 miRNAs were upregulated and 3 downregulated in the normal appearing buccal mucosal cells collected from patients harboring lung cancer (n=76). The performance characteristics of selected miRNAs (with ≥1-fold change) were excellent with an average under the receiver operator characteristic curve (AUROC) of >0.80. Several miRNAs also displayed gender specificity between the groups. These results provide the first proof-of-concept scenario in which minimally intrusive cheek brushings could provide an initial screening tool in a large at-risk population.

miRNA as markers for the diagnostic screening of colon cancer

Early screening for colon cancer (CC) allows for early stage diagnosis of the malignancy and potentially reduces disease mortality as the cancer is most likely curable at its earliest stages. Early detection would be desirable if accurate, practical and cost-effective diagnostic measures for this cancer were available. Mortality and morbidity from CC represent a major health problem involving a malignant disease that is theoretically preventable through screening. Current screening methods (e.g., the convenient and inexpensive immunological fecal occult blood test, FOBTi, obtained from patients' medical records) either lack sensitivity and require dietary restriction, which impedes compliance and use; are costly (e.g., colonoscopy), which decreases compliance; or could result in mortality. In comparison with the FOBT test, a non-invasive sensitive screen for which there is no requirement for dietary restriction would be a more convenient test. Colorectal cancer is the only cancer for which colonoscopy is recommended as a screening method. Although colonoscopy is a reliable screening tool, the invasive nature, abdominal pain, potential complications and high cost have hampered the application of this procedure worldwide. A screening approach using the stable miRNA molecules, which are relatively non-degradable when extracted from non-invasive stool and semi-invasive blood samples by commercially available kits and manipulated thereafter, would be preferable to a transcriptomic mRNA-, a mutation DNA-, an epigenetic- or a proteomic-based test. The approach uses reverse transcriptase, modified real-time quantitative PCR. Although exosomal RNA would be missed, using a restricted extraction of total RNA from stool or blood, a parallel test could also be carried out on RNA obtained from stool or plasma samples, and appropriate corrections for exsosomal loss can be made for accurate and quantitative test result. Eventually, a chip can be developed to facilitate diagnosis, as has been done for the quantification of genetically modified organisms in foods. The gold standard to which the molecular miRNA test is compared is colonoscopy, which can be obtained from patients' medical records. If performance criteria are met, as detailed herein, a miRNA test in human stool or blood samples based on high-throughput automated technologies and quantitative expression measurements commonly used in the diagnostic clinical laboratory should be advanced to the clinical setting, which will make a significant impact on CC prevention.

Overexpression of arginine transporter CAT-1 is associated with accumulation of L-arginine and cell growth in human colorectal cancer tissue

We previously showed that L-arginine (Arg) accumulates in colorectal cancer tissues. The aim of this study was to investigate the mechanism by which Arg accumulates and determine its biological significance. The concentration of Arg and Citrulline (Cit) in sera and tumor tissues from colorectal cancer (CRC) patients was analyzed by high-performance liquid chromatography (HPLC). The expression of Arg transporters was analyzed by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and immunohistochemical analysis of tissue microarray. We also transfected the colon cancer cell line HCT-116 with siRNA specific for the Arg transporter CAT-1 and measured the induction of apoptosis by flow cytometry and cell proliferation by MTT assay. Consistent with our previous results, serum Arg and Cit concentrations in colorectal cancer patients were significantly lower than those in normal volunteers, while Arg and Cit concentrations in colorectal cancer tissues were significantly higher than in matched adjacent normal colon tissues. Quantitative RT-PCR showed that the CAT-1 gene was highly overexpressed in 70.5% of colorectal cancer tissue samples relative to adjacent normal colon tissues in all 122 patients with colorectal cancer. Immunohistochemical analysis of tissue microarray confirmed that the expression of CAT-1 was higher in all 25 colorectal cancer tissues tested. CAT-1 siRNA significantly induced apoptosis of HCT-116 cells and subsequently inhibited cell growth by 20–50%. Our findings indicate that accumulation of L-Arg and Cit and cell growth in colorectal cancer tissues is associated with over-expression of the Arg transporter gene CAT-1. Our results may be useful for the development of molecular diagnostic tools and targeted therapy for colorectal cancer.

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.