Genetic variation rs7930 in the miR-4273-5p target site is associated with a risk of colorectal cancer

An Endosomal Acid-Regulatory Feedback System Rewires Cytosolic cAMP Metabolism and Drives Tumor Progression

Although suppressed cAMP levels have been linked to cancer for nearly five decades, the molecular basis remains uncertain. Here, we identify endosomal pH as a novel regulator of cytosolic cAMP homeostasis and a promoter of transformed phenotypic traits in colorectal cancer. Combining experiments and computational analysis, we show that the Na+/H+ exchanger NHE9 contributes to proton leak and causes luminal alkalinization, which induces resting [Ca2+], and in consequence, represses cAMP levels, creating a feedback loop that echoes nutrient deprivation or hypoxia. Higher NHE9 expression in cancer epithelia is associated with a hybrid epithelial-mesenchymal (E/M) state, poor prognosis, tumor budding, and invasive growth in vitro and in vivo. These findings point to NHE9-mediated cAMP suppression as a pseudostarvation-induced invasion state and potential therapeutic vulnerability in colorectal cancer. Our observations lay the groundwork for future research into the complexities of endosome-driven metabolic reprogramming and phenotype switching and the biology of cancer progression.

IMPLICATIONS

Endosomal pH regulator NHE9 actively controls cytosolic Ca2+ levels to downregulate the adenylate cyclase-cAMP system, enabling colorectal cancer cells to acquire hybrid E/M characteristics and promoting metastatic progression.

Identification of neoplasm-specific signatures of miRNA interactions by employing a systems biology approach

MicroRNAs represent major regulatory components of the disease epigenome and they constitute powerful biomarkers for the accurate diagnosis and prognosis of various diseases, including cancers. The advent of high-throughput technologies facilitated the generation of a vast amount of miRNA-cancer association data. Computational approaches have been utilized widely to effectively analyze and interpret these data towards the identification of miRNA signatures for diverse types of cancers. Herein, a novel computational workflow was applied to discover core sets of miRNA interactions for the major groups of neoplastic diseases by employing network-based methods. To this end, miRNA-cancer association data from four comprehensive publicly available resources were utilized for constructing miRNA-centered networks for each major group of neoplasms. The corresponding miRNA-miRNA interactions were inferred based on shared functionally related target genes. The topological attributes of the generated networks were investigated in order to detect clusters of highly interconnected miRNAs that form core modules in each network. Those modules that exhibited the highest degree of mutual exclusivity were selected from each graph. In this way, neoplasm-specific miRNA modules were identified that could represent potential signatures for the corresponding diseases.

MicroRNAs in Genetic Etiology of Human Diseases

Since their first discovery more than 20 years ago, miRNAs have been subject to deliberate research and analysis for revealing their physiological or pathological involvement. Regulatory roles of miRNAs in signal transduction, gene expression, and cellular processes in development, differentiation, proliferation, apoptosis, and homeostasis also imply their critical role in disease pathogenesis. Their roles in cancer, neurodegenerative diseases, and other systemic diseases have been studied broadly. In these regulatory pathways, their mutations and target sequence variations play critical roles to determine their functional repertoire. In this chapter, we summarize studies that investigated the role of mutations, polymorphisms, and other variations of miRNAs in respect to pathological processes.

Non-Coding Variants in Cancer: Mechanistic Insights and Clinical Potential for Personalized Medicine

The cancer genome is characterized by extensive variability, in the form of Single Nucleotide Polymorphisms (SNPs) or structural variations such as Copy Number Alterations (CNAs) across wider genomic areas. At the molecular level, most SNPs and/or CNAs reside in non-coding sequences, ultimately affecting the regulation of oncogenes and/or tumor-suppressors in a cancer-specific manner. Notably, inherited non-coding variants can predispose for cancer decades prior to disease onset. Furthermore, accumulation of additional non-coding driver mutations during progression of the disease, gives rise to genomic instability, acting as the driving force of neoplastic development and malignant evolution. Therefore, detection and characterization of such mutations can improve risk assessment for healthy carriers and expand the diagnostic and therapeutic toolbox for the patient. This review focuses on functional variants that reside in transcribed or not transcribed non-coding regions of the cancer genome and presents a collection of appropriate state-of-the-art methodologies to study them.

Identifying the Signatures and Rules of Circulating Extracellular MicroRNA for Distinguishing Cancer Subtypes

Cancer is one of the most threatening diseases to humans. It can invade multiple significant organs, including lung, liver, stomach, pancreas, and even brain. The identification of cancer biomarkers is one of the most significant components of cancer studies as the foundation of clinical cancer diagnosis and related drug development. During the large-scale screening for cancer prevention and early diagnosis, obtaining cancer-related tissues is impossible. Thus, the identification of cancer-associated circulating biomarkers from liquid biopsy targeting has been proposed and has become the most important direction for research on clinical cancer diagnosis. Here, we analyzed pan-cancer extracellular microRNA profiles by using multiple machine-learning models. The extracellular microRNA profiles on 11 cancer types and non-cancer were first analyzed by Boruta to extract important microRNAs. Selected microRNAs were then evaluated by the Max-Relevance and Min-Redundancy feature selection method, resulting in a feature list, which were fed into the incremental feature selection method to identify candidate circulating extracellular microRNA for cancer recognition and classification. A series of quantitative classification rules was also established for such cancer classification, thereby providing a solid research foundation for further biomarker exploration and functional analyses of tumorigenesis at the level of circulating extracellular microRNA.

TOMM20 as a potential therapeutic target of colorectal cancer

Translocase of outer mitochondrial membrane 20 (TOMM20) plays an essential role as a receptor for proteins targeted to mitochondria. TOMM20 was shown to be overexpressed in various cancers. However, the oncological function and therapeutic potential for TOMM20 in cancer remains largely unexplored. The purpose of this study was to elucidate the underlying molecular mechanism of TOMM20's contribution to tumorigenesis and to explore the possibility of its therapeutic potential using colorectal cancer as a model. The results show that TOMM20 overexpression resulted in an increase in cell proliferation, migration, and invasion of colorectal cancer (CRC) cells, while siRNA-mediated inhibition of TOMM20 resulted in significant decreases in cell proliferation, migration, and invasion. TOMM20 expression directly impacted the mitochondrial function including ATP production and maintenance of membrane potential, which contributed to tumorigenic cellular activities including regulation of S phase cell cycle and apoptosis. TOMM20 was overexpressed in CRC compared to the normal tissues and increased expression of TOMM20 to be associated with malignant characteristics including a higher number of lymph nodes and perineural invasion in CRC. Notably, knockdown of TOMM20 in the xenograft mouse model resulted in a significant reduction of tumor growth. This is the first report demonstrating a relationship between TOMM20 and tumorigenesis in colorectal cancer and providing promising evidence for the potential for TOMM20 to serve as a new therapeutic target of colorectal cancer. [BMB Reports 2019; 52(12): 712-717].

Allele-specific miRNA-binding analysis identifies candidate target genes for breast cancer risk

Most breast cancer (BC) risk-associated single-nucleotide polymorphisms (raSNPs) identified in genome-wide association studies (GWAS) are believed to cis-regulate the expression of genes. We hypothesise that cis-regulatory variants contributing to disease risk may be affecting microRNA (miRNA) genes and/or miRNA binding. To test this, we adapted two miRNA-binding prediction algorithms-TargetScan and miRanda-to perform allele-specific queries, and integrated differential allelic expression (DAE) and expression quantitative trait loci (eQTL) data, to query 150 genome-wide significant ( P ≤ 5 × 10 - 8 ) raSNPs, plus proxies. We found that no raSNP mapped to a miRNA gene, suggesting that altered miRNA targeting is an unlikely mechanism involved in BC risk. Also, 11.5% (6 out of 52) raSNPs located in 3'-untranslated regions of putative miRNA target genes were predicted to alter miRNA::mRNA (messenger RNA) pair binding stability in five candidate target genes. Of these, we propose RNF115, at locus 1q21.1, as a strong novel target gene associated with BC risk, and reinforce the role of miRNA-mediated cis-regulation at locus 19p13.11. We believe that integrating allele-specific querying in miRNA-binding prediction, and data supporting cis-regulation of expression, improves the identification of candidate target genes in BC risk, as well as in other common cancers and complex diseases.

Mutant ACTB mRNA 3'-UTR promotes hepatocellular carcinoma development by regulating miR-1 and miR-29a

In recent years, studies demonstrate that ACTB has been found to be associated with various tumors. Although ACTB is dysregulated in numerous cancer types, limited data are available on the potential function and mechanism of ACTB in hepatocellular carcinoma (HCC). This study evaluated the expression and biological roles of mutant ACTB mRNA 3'-UTR in HCC. Transcriptome sequence and qRT-PCR analysis determined that mutant ACTB mRNA '-UTR was high expression in tumor tissues. Luciferase reporter assay showed that the ACTB mRNA 3'-UTR mutations made it easier to interact with miR-1 and miR-29a. Moreover, mutant ACTB mRNA '-UTR regulated miR-1 and miR-29a degradation via AGO2. Furthermore, mutant ACTB mRNA 3'-UTR promoted hepatocellular carcinoma cells migration and invasion in vitro and in vivo by up-regulating miR-1 target gene MET and miR-29a target gene MCL1. In a word, our study demonstrates that 3'-UTR of ACTB plays a key role in the development of hepatocellular carcinoma (HCC) and highlights the molecular mechanisms underlying such a complex process.

MicroRNA-binding site polymorphisms and risk of colorectal cancer: A systematic review and meta-analysis

Genetic variations in miRNAs binding site might participate in cancer risk. This study aimed to systematically review the association between miRNA‐binding site polymorphisms and colorectal cancer (CRC). Electronic literature search was carried out on PubMed, Web of Science (WOS), Scopus, and Embase. All types of observational studies till 30 November 2018 were included. Overall 85 studies (21 SNPs) from two systematic searches were included analysis. The results showed that in the Middle East population, the minor allele of rs731236 was associated with decreased risk of CRC (heterozygote model: 0.76 [0.61‐0.95]). The minor allele of rs3025039 was related to increased risk of CRC in East Asian population (allelic model: 1.25 [1.01‐1.54]). Results for rs3212986 were significant in overall and subgroup analysis (P < .05). For rs1801157 in subgroup analysis the association was significant in Asian populations (including allelic model: 2.28 [1.11‐4.69]). For rs712, subgroup analysis revealed a significant (allelic model: 1.41 [1.23‐1.61]) and borderline (allelic model: 0.92 [0.84‐1.00]) association in Chinese and Czech populations, respectively. The minor allele of rs17281995 increased risk of CRC in different genetic models (P < .05). Finally, rs5275, rs4648298, and rs61764370 did not show significant associations. In conclusion, minor allele of rs3025039, rs3212986, and rs712 polymorphisms increases the risk of CRC in the East Asian population, and heterozygote model of rs731236 polymorphism shows protective effect in the Middle East population. In Europeans, the minor allele of rs17281995 may increase the risk of CRC, while rs712 may have a protective effect. Further analysis based on population stratifications should be considered in future studies.

Functional polymorphism within miR-23a∼27a∼24-2 cluster confers clinical outcome of breast cancer in Pakistani cohort

AIM

MicroRNAs (miRNAs) are small regulatory RNA molecules that control gene activity by base pairing with target messenger RNA leading to their cleavage or translational repression. Previous studies show an involvement of miRNAs in various diseases including cancer. Members of the Mir-23a cluster (MIR23A, MIR24-2 and MIR27A) are involved in breast cancer (BC).

METHODS

In the present study, miR-23a/24-2/27a cluster was screened for genetic mutation in BC patients.

RESULTS

Heterozygous (A/G allele) as well as homozygous (G/G allele) variants were found in mir-27a gene in screened BC patients. RNA structural analysis revealed that the single nucleotide polymorphism (SNP) effects the size of the terminal loop in the precursor miRNA (pre-miRNA).

CONCLUSION

The altered (G allele) hairpin structure observed was two bases longer than the reference (A allele) hairpin.

Exploring the Impact of Single-Nucleotide Polymorphisms on Translation

Over the past 15 years, sequencing of the human genome and The Cancer Genome Atlas (TCGA) project have led to comprehensive lists of single-nucleotide polymorphisms (SNPs) and gene mutations across a large number of human samples. However, our ability to predict the functional impact of SNPs and mutations on gene expression is still in its infancy. Here, we provide key examples to help understand how mutations present in genes can affect translational output.

Levels of MicroRNA Heterogeneity in Cancer Biology

MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression, involved in the silencing of messenger RNA (mRNA) translation. The importance of miRNA signatures in disease screening, prognosis, and progression of different tumor types and subtypes is increasing. miRNA expression levels change depending on numerous factors. In this review, we are describing the circumstances under which miRNA levels can change, these are named 'levels' of heterogeneity of miRNAs. miRNAs can have oncogenic, tumor suppressive, or both roles depending on tumor type and target mRNA whose translation they silence. The expression levels of a single miRNA may vary across different cancer types and subtypes, indicating that a miRNA signature may be tissue specific. miRNA levels of expression also vary during disease formation and propagation, indicating the presence of a time profile for their expression. The complexity of the miRNA-mRNA interference network mirrors different genetic and epigenetic changes that influence miRNA and mRNA availability to each other, and hence, their binding ability. The potential role of miRNAs as biomarkers is two-fold; first, for monitoring of the phases of cancer pathogenesis, and second, to characterize the particular type/subtype of cancer. It is important that a particular miRNA should be characterized by examining as many types and subtypes of cancers as are available, as well as being extracted from different types of samples, in order to obtain a complete picture of its behavior and importance in the disease pathology.

Association of two microRNA polymorphisms miR-27 rs895819 and miR-423 rs6505162 with the risk of cancer

Many studies have been conducted to investigate the association between miR-27 rs895819 A > G and miR-423 rs6505162 C > A and cancer risk; however, the results are not consistent. In order to acquire a more precise assessment of the correlation, we performed this meta-analysis. We searched PubMed, EMBASE and Web of Science databases to identify eligible studies. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were applied to evaluate the correlation of these two microRNA polymorphisms with cancer risk. Forty-five eligible studies from thirty-five articles were included in our analysis. The results showed that rs895819 was associated with a decreased cancer risk in Caucasians (AG vs. AA: OR = 0.87, 95% CI = 0.79-0.96; GG+AG vs. AA: OR = 0.89, 95% CI = 0.81-0.98). When grouped by ethnicity, an increased risk was observed in colorectal cancer (G vs. A: OR = 1.19, 95% CI = 1.08-1.32; GG vs. AA: OR = 1.58, 95% CI = 1.28-1.96; GG vs. AG+AA: OR = 1.58, 95% CI = 1.29-1.93), while a decreased risk was found in breast cancer (G vs. A: OR = 0.93, 95% CI = 0.87-0.99; GG+AG vs. AA: OR = 0.91, 95% CI = 0.83-0.99). For rs6505162, a significantly decreased cancer risk was observed in lung cancer under all five genetic models. To summarize, our results indicated that rs895819 was a protective factor for cancer in Caucasians and could increase colorectal cancer risk but decrease breast cancer risk. Moreover, rs6505162 was a protective factor for lung cancer.

Unveiling massive numbers of cancer-related urinary-microRNA candidates via nanowires

Analyzing microRNAs (miRNAs) within urine extracellular vesicles (EVs) is important for realizing miRNA-based, simple, and noninvasive early disease diagnoses and timely medical checkups. However, the inherent difficulty in collecting dilute concentrations of EVs (<0.01 volume %) from urine has hindered the development of these diagnoses and medical checkups. We propose a device composed of nanowires anchored into a microfluidic substrate. This device enables EV collections at high efficiency and in situ extractions of various miRNAs of different sequences (around 1000 types) that significantly exceed the number of species being extracted by the conventional ultracentrifugation method. The mechanical stability of nanowires anchored into substrates during buffer flow and the electrostatic collection of EVs onto the nanowires are the two key mechanisms that ensure the success of the proposed device. In addition, we use our methodology to identify urinary miRNAs that could potentially serve as biomarkers for cancer not only for urologic malignancies (bladder and prostate) but also for nonurologic ones (lung, pancreas, and liver). The present device concept will provide a foundation for work toward the long-term goal of urine-based early diagnoses and medical checkups for cancer.

A new model of the mechanism underlying lead poisoning: SNPs in miRNA target region influence the δ-aminolevulinic acid dehydratase expression level

AIM

To determine if SNPs located within the 3'-UTR of δ-aminolevulinic acid dehydratase (ALAD) can alter the risk of lead poisoning and the ALAD gene expression.

MATERIALS & METHODS

A case-control study was carried out to find the SNPs in miRNA target region. Luciferase reporter gene assay, qRT-PCR and Western blot was used to determine the relationship between miRNA and SNPs.

RESULTS

We found a significant association between rs818708 and the risk of lead poisoning. miR-545-5p was influenced by rs818708 variant and might result in a significant change in ALAD expression.

CONCLUSION

rs818708 T > C can weaken the binding capability between miR-545-5p and 3'-UTR of ALAD and thus may alter the risk of lead poisoning.

Association of miR-21, miR-126 and miR-605 gene polymorphisms with ischemic stroke risk

We investigated whether three common microRNA polymorphisms (miR-21T>C [rs1292037], miR-126G>A [rs4636297] and miR-605T>C [rs2043556]) were associated with ischemic stroke (IS) risk in a Chinese population. The study population comprised 592 ischemic stroke patients and 456 normal controls. The polymorphisms were measured using Snapshot SNP genotyping assays and confirmed by sequencing. Relative expressions of miR-21, miR-126 and miR-605 were measured by quantitative real-time PCR. We found that miR-126 gene rs4636297 polymorphism was associated with decreased ischemic stroke risk (GA vs. GG: AOR=0.64, adjust P=0.025; AA vs. GG: AOR=0.32, adjust P=0.007; dominant model: AOR=0.58, adjust P=0.004). MiR-21 gene rs1292037 and miR-605 gene rs2043556 polymorphisms were not associated with ischemic stroke risk. In addition, compared with normal controls, serum miR-126 level was significantly decreased in ischemic stroke patients, while the miR-21 level was significantly increased. Importantly, patients carrying rs4636297 GA/AA genotypes had higher serum miR-126 level (P<0.05). MiR-126 gene rs4636297 polymorphism and serum miR-126/-21 levels are associated with ischemic stroke risk. Our data indicates that miR-126 and miR-21 play roles in the development of ischemic stroke.

microRNAs Make the Call in Cancer Personalized Medicine

Since their discovery and the advent of RNA interference, microRNAs have drawn enormous attention because of their ubiquitous involvement in cellular pathways from life to death, from metabolism to communication. It is also widely accepted that they possess an undeniable role in cancer both as tumor suppressors and tumor promoters modulating cell proliferation and migration, epithelial-mesenchymal transition and tumor cell invasion and metastasis. Moreover, microRNAs can even affect the tumor surrounding environment influencing angiogenesis and immune system activation and recruitment. The tight association of microRNAs with several cancer-related processes makes them undoubtedly connected to the effect of specific cancer drugs inducing either resistance or sensitization. In this context, personalized medicine through microRNAs arose recently with the discovery of single nucleotide polymorphisms in the target binding sites, in the sequence of the microRNA itself or in microRNA biogenesis related genes, increasing risk, susceptibility and progression of multiple types of cancer in different sets of the population. The depicted scenario implies that the overall variation displayed by these small non-coding RNAs have an impact on patient-specific pharmacokinetics and pharmacodynamics of cancer drugs, pushing on a rising need of personalized treatment. Indeed, microRNAs from either tissues or liquid biopsies are also extensively studied as valuable biomarkers for disease early recognition, progression and prognosis. Despite microRNAs being intensively studied in recent years, a comprehensive review describing these topics all in one is missing. Here we report an up-to-date and critical summary of microRNAs as tools for better understanding personalized cancer biogenesis, evolution, diagnosis and treatment.

Dietary factors and polymorphisms in vitamin D metabolism genes: the risk and prognosis of colorectal cancer in northeast China

CYP24A1 and CYP27B1 are critical genes determining 1α,25(OH)₂D₃ concentration and impacting on carcinogenesis. A case–control study including 528 colorectal cancer (CRC) patients and 605 cancer-free controls and a follow-up study with 317 cases were conducted in northeast China. Genotypes were tested by TaqMan Genotyping Assays. Individuals carrying the GG genotype of CYP27B1 G > T (rs10877012) exhibited decreased CRC risk compared with those with the TT genotype (OR_adjusted (OR_adj) = 0.57, 95% Confidence Interval (CI) = 0.38–0.84). Compared with the TT genotype, a significant association between the CC genotype of CYP27B1 C > T (rs4646536) and a reduced risk of CRC was observed (OR_adj = 0.59, 95% CI = 0.40–0.88). We also observed significant combined effects of the two polymorphisms in CYP27B1 with dietary factors, including the intake of cereals, overnight meal, allium vegetables, pork, canned fruit, and braised fish, on CRC risk. These associations remained significant after Bonferroni correction for multiple comparisons. The Hazard Ration (HR) of patients with the AA genotype (CYP24A1 A > G, rs4809957) was 2.38 (95% CI = 1.30–4.37) when compared with the GG genotype. Thus, our findings suggested that two polymorphisms in CYP27B1 are associated with CRC susceptibility. CYP24A1 A > G (rs4809957) polymorphism may lead to a worse prognosis of CRC.

Interactions between polymorphisms in the 3'untranslated region of the cyclin dependent kinase 6 gene and the human papillomavirus infection, and risk of cervical precancerous lesions

The human papillomavirus (HPV) infection is essential for the development of cervical cancer and its precursor lesions. However, only certain persistently infected individuals develop cervical cancer. Cyclin-dependent kinase 6 (CDK6) is a critical regulatory cancer-associated gene in the cell cycle and in tumorigenesis. Single nucleotide polymorphisms (SNPs) in microRNA sites in the 3′-untranslated region (UTR) of target genes may result in target gene expression level changes and susceptibility to diseases, including cancer. Therefore, the aim of the present study was to determine whether SNPs in the 3′UTR of the CDK6 gene may affect susceptibility to cervical precancerous lesions in a Chinese population. Five polymorphisms in the 3′UTR of the CDK6 gene were evaluated in 164 cervical precancerous lesion cases and 296 control subjects. Differences in environmental factors between cases and controls were evaluated using the χ² test or unpaired t-test. Logistic regression was used to examine the association between the five polymorphisms and cervical precancerous lesions. The model-free multifactor dimensionality reduction (MDR) method was performed to evaluate the interaction effect of environment variables and gene polymorphisms. Interactions on the additive scale are calculated by using the relative excess risk due to interaction (RERI). After controlling for potential confounders, a significantly decreased risk of cervical precancerous lesions for the GA genotype, rs8179, and the AT genotype, rs42033 [GA vs. GA: odds ratio (OR)_adjusted=0.17, 95% confidence interval (CI), 0.05–0.57; AT vs. AA: OR_adjusted=0.18, 95% CI, 0.05–0.59, respectively] was identified. Furthermore, following MDR analysis, a significant three-locus interaction model was identified, which involved the HPV infection, the number of pregnancies and rs8179. Additionally, a significant antagonistic interaction between the HPV infection and rs8179 was identified on an additive scale. Haplotype AGTA was associated with a decreased risk of developing cervical precancerous lesions (OR_adjusted=0.21; 95% CI, 0.06–0.75). Thus, the present results indicated that the rs8179 and rs42033 polymorphisms confer genetic susceptibility to cervical precancerous lesions. Furthermore, the interaction between the rs8179 polymorphism in CDK6 and the HPV infection and haplotype AGTA may be associated with cervical precancerous lesions.