Sequence variation in mature microRNA-608 and benefit from neo-adjuvant treatment in locally advanced rectal cancer patients

Biological Functions and Molecular Mechanisms of MiR-608 in Cancer

In recent years, microRNAs (miRNAs) have attracted much attention because of their prominent role in cancer. An increasing number of studies have shown that miRNAs play an important role in a variety of tumors. miR-608 has been reported to be decreased in cancers, especially in solid tumors. miR-608 is regarded as a tumor suppressor, which has been verified through a large number of experiments both in vivo and in vitro. miR-608 participates in many biological processes, including cell proliferation, invasion, migration, and apoptosis, by inhibiting transmembrane proteins and many signaling pathways. Here, we summarize the expression profile and biological functions and mechanism of miR-608, suggesting that miR-608 is an ideal diagnostic and prognostic biomarker and a treatment target for cancer.

Single Nucleotide Polymorphisms in microRNA Genes and Colorectal Cancer Risk and Prognosis

There is growing interest in single nucleotide polymorphisms (SNPs) in the genes of microRNAs (miRNAs), which could be associated with susceptibility to colorectal cancer (CRC) and therefore for prognosis of the disease and/or treatment response. Moreover, these miRNAs-SNPs could serve as new, low-invasive biomarkers for early detection of CRC. In the present article, we performed a thorough review of different SNPs, which were investigated for a correlation with the CRC risk, prognosis, and treatment response. We also analyzed the results from different meta-analyses and the possible reasons for reported contradictory findings, especially when different research groups investigated the same SNP in a gene for a particular miRNA. This illustrates the need for more case-control studies involving participants with different ethnic backgrounds. According to our review, three miRNAs-SNPs-miR-146a rs2910164, miR-27a rs895819 and miR-608 rs4919510-appear as promising prognostic, diagnostic and predictive biomarkers for CRC, respectively.

Complete pathological response in rectal cancer utilising novel treatment strategies for neo-adjuvant therapy: A systematic review

BACKGROUND

Locally advanced rectal cancer is routinely treated with neo-adjuvant long course chemoradiotherapy or short course radiotherapy, followed by total mesorectal excision. Not all patients respond to this treatment and there has been an emergence of novel treatment strategies designed to improve outcomes for these patients. This systematic review aims to assess the current novel neo-adjuvant treatment strategies being utilised in the treatment of patients with rectal cancer and how these impact pathological complete response (pCR) rates.

METHODS

A systematic review of the literature was performed to evaluate pathological response in patients with rectal cancer receiving novel neo-adjuvant therapy. EMBASE and Medline electronic databases were searched for relevant articles. Articles published between January 2008 and February 2019 were retrieved. Included studies underwent critical appraisal and complete pathological response rates were recorded.

RESULTS

Of the initial 1074 articles identified, 217 articles fulfilled the inclusion criteria, of these 60 articles (4359 patients) were included. Neo-adjuvant therapy delivered included novel long course chemoradiation therapy, neoadjuvant chemotherapy alone, addition of a biological agent, total neo-adjuvant therapy, novel short course radiation therapy and studies utilising biomarkers to select patients for therapy. Complete pathological response rates ranged from 0 to 60%.

CONCLUSION

A validated novel neo-adjuvant therapy that significantly increases pCR rates in patients with rectal cancer has not been identified.

miR-608 rs4919510 Polymorphism May Affect Susceptibility to Colorectal Cancer by Upregulating MRPL43 Expression

There are many studies on the association between miR-608 rs4919510 polymorphism and susceptibility to colorectal cancer (CRC). However, the role of rs4919510 in CRC development and its underlying mechanism remain unclear. We first evaluated the gene that may be regulated by the variation of rs4919510 through a two-stage expression quantitative trait loci analysis and then compared the expression of that identified gene in CRC tissues and adjacent nontumor tissues. Next, methyl thiazolyl tetrazolium (MTT) assay, transwell assay, and flow cytometry analyses were performed to investigate the in vitro capacity of cell proliferation, migration, invasion, apoptosis, and cell cycle of CRC cells, respectively. Finally, through bioinformatics prediction, we contrasted the regulatory network and identified microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) that could regulate the obtained gene. We found that the variant G allele of rs4919510 located in miR-608 was associated with a potentially increased expression of MRPL43 in colon tissues (p = 0.065). Moreover, the results of functional experiments suggested that knockdown of the MRPL43 gene could inhibit the growth of the CRC HCT-116 cell line and promote apoptosis. Additionally, the cell cycle of CRC HCT-116 cell line was significantly arrested at the G2 phase. Next, we obtained a competing endogenous RNA regulatory network of MRPL43 with 17 pairs of miRNAs-lncRNAs by bioinformatics prediction, out of which, survival analysis indicated that different expression levels of miR-193b-3p (p = 0.0269) and miR-194-3p (p = 0.0113) were associated with overall survival in CRC patients. The rs4919510 variant G allele in miR-608 may increase the proliferation, invasion, and migration ability and decrease the apoptosis of CRC HCT-116 cell line by upregulating the expression of MRPL43, ultimately may affect the risk of CRC. Moreover, miR-193b-3p and miR-194-3p that target MRPL43 may serve as potential predictive biomarkers of CRC survival.

The Role of Micro-RNAs and Circulating Tumor Markers as Predictors of Response to Neoadjuvant Therapy in Locally Advanced Rectal Cancer

The response to neoadjuvant chemoradiation (nCRT) is a critical step in the management of locally advanced rectal cancer (LARC) patients. Only a minority of LARC patients responds completely to neoadjuvant treatments, thus avoiding invasive radical surgical resection. Moreover, toxic side effects can adversely affect patients' survival. The difficulty in separating in advances responder from non-responder patients affected by LARC highlights the need for valid biomarkers that guide clinical decision-making. In this context, microRNAs (miRNAs) seem to be promising candidates for predicting LARC prognosis and/or therapy response, particularly due to their stability, facile detection, and disease-specific expression in human tissues, blood, serum, or urine. Although a considerable number of studies involving potential miRNA predictors to nCRT have been conducted over the years, to date, the identification of the perfect miRNA signatures or single miRNA, as well as their use in the clinical practice, is still representing a challenge for the management of LARC patients. In this review, we will first introduce LARC and its difficult management. Then, we will trace the scientific history and the key obstacles for the identification of specific miRNAs that predict responsiveness to nCRT. There is a high potential to identify non-invasive biomarkers that circulate in the human bloodstream and that might indicate the LARC patients who benefit from the watch-and-wait approach. For this, we will critically evaluate recent advances dealing with cell-free nucleic acids including miRNAs and circulating tumor cells as prognostic or predictive biomarkers.

Germline and Somatic Pharmacogenomics to Refine Rectal Cancer Patients Selection for Neo-Adjuvant Chemoradiotherapy

Neoadjuvant chemoradiotherapy (nCRT) followed by radical surgery is the standard of care for patients with Locally Advanced Rectal Cancer (LARC). Current selection for nCRT is based on clinical criteria regardless of any molecular marker. Pharmacogenomics may be a useful strategy to personalize and optimize nCRT in LARC. This review aims to summarize the most recent and relevant findings about the role of germline and somatic pharmacogenomics in the prediction of nCRT outcome in patients with LARC, discussing the state of the art of their application in the clinical practice. A systematic literature search of the PubMed database was completed to identify relevant English-language papers published up to January 2020. The chemotherapeutic backbone of nCRT is represented by fluoropyrimidines, mainly metabolized by DPD (Dihydro-Pyrimidine Dehydrogenase, DPYD). The clinical impact of testing DPYD*2A, DPYD*13, c.2846A > T and c.1236G > A-HapB3 before a fluoropyrimidines administration to increase treatment safety is widely acknowledged. Other relevant target genes are TYMS (Thymidylate Synthase) and MTHFR (Methylene-Tetrahydro-Folate Reductase), whose polymorphisms were mainly studied as potential markers of treatment efficacy in LARC. A pivotal role of a TYMS polymorphism in the gene promoter region (rs34743033) was reported and was pioneeringly used to guide nCRT treatment in a phase II study. The pharmacogenomic analysis of other pathways mostly involved in the cellular response to radiation damage, as the DNA repair and the activation of the inflammatory cascade, provided less consistent results. A high rate of somatic mutation in genes belonging to PI3K (Phosphatidyl-Inositol 3-Kinase) and MAPK (Mitogen-Activated Protein Kinase) pathways, as BRAF (V-raf murine sarcoma viral oncogene homolog B1), KRAS (Kirsten Rat Sarcoma viral oncogene homolog), NRAS (Neuroblastoma RAS viral (v-ras) oncogene homolog), PIK3CA (Phosphatidyl-Inositol-4,5-bisphosphate 3-Kinase, Catalytic Subunit Alpha), as well as TP53 (Tumor Protein 53) was reported in LARC. Their pharmacogenomic role, already defined in colorectal cancer, is under investigation in LARC with promising results concerning specific somatic mutations in KRAS and TP53, as predictors of tumor response and prognosis. The availability of circulating tumor DNA in plasma may also represent an opportunity to monitor somatic mutations in course of therapy.

MicroRNAs (miRNAs) and Long Non-Coding RNAs (lncRNAs) as New Tools for Cancer Therapy: First Steps from Bench to Bedside

Non-coding RNAs represent a significant proportion of the human genome. After having been considered as 'junk' for a long time, non-coding RNAs are now well established as playing important roles in maintaining cellular homeostasis and functions. Some non-coding RNAs show cell- and tissue-specific expression patterns and are specifically deregulated under pathological conditions (e.g. cancer). Therefore, non-coding RNAs have been extensively studied as potential biomarkers in the context of different diseases with a focus on microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) for several years. Since their discovery, miRNAs have attracted more attention than lncRNAs in research studies; however, both families of non-coding RNAs have been established to play an important role in gene expression control, either as transcriptional or post-transcriptional regulators. Both miRNAs and lncRNAs can regulate key genes involved in the development of cancer, thus influencing tumour growth, invasion, and metastasis by increasing the activation of oncogenic pathways and limiting the expression of tumour suppressors. Furthermore, miRNAs and lncRNAs are also emerging as important mediators in drug-sensitivity and drug-resistance mechanisms. In the light of these premises, a number of pre-clinical and early clinical studies are exploring the potential of non-coding RNAs as new therapeutics. The aim of this review is to summarise the latest knowledge of the use of miRNAs and lncRNAs as therapeutic tools for cancer treatment.

miR-608 and miR-4513 significantly contribute to the prognosis of lung adenocarcinoma treated with EGFR-TKIs

Tyrosine kinase inhibitors (TKIs) targeting epidermal growth factor receptors (EGFR) significantly prolong the survival of lung adenocarcinoma patients with sensitizing EGFR mutations. Unfortunately, 10-30% patients do not show objective responses to EGFR-TKIs, and undergo rapid disease progression during the EGFR-TKIs therapy. Single nucleotide polymorphisms (SNPs) in mature microRNA (miRNA) sequences may influence target site interactions and modulate downstream pathways, such as the EGFR pathway. For this reason, we hypothesized that miRNA SNPs may impact the prognosis of lung adenocarcinoma patients after EGFR-TKI treatment. By systematically screening of the miRbase and the 1000 genomes project databases, we successfully identified five mature miRNA SNPs. Genotypes were determined in two independent cohorts (Hubei and Shandong cohorts) that include 319 EGFR-TKI treated stage IIIB/IV patients. The impact of miR-608 and miR-4513 on the drug sensitivity of gefitinib was examined in lung adenocarcinoma cells. miR-608 rs4919510 or miR-4513 rs2168518 significantly contributed to the progression-free survival (PFS) in the Hubei cohort (hazard ratio [HR] = 0.63, confidence interval [CI] = 0.49-0.81, P = 3.0 × 10^-4 or HR = 0.46, 95% CI = 0.31-0.67, P = 8.0 × 10^-5). These observations were further validated in the Shandong cohort (P = 0.005 or P = 0.001). Similarly, the miR-608 rs4919510 CC genotype or the miR-4513 rs2168518 GA genotype was significantly associated with decreased death risk after gefitinib treatment, compared with the rs4919510 GG genotype (Hubei cohort: P = 5.0 × 10^-4; Shandong cohort: P = 0.004) or the rs2168518 GG genotype (P = 4.9 × 10^-5; P = 0.002). Consistently, miR-608 significantly increased the anti-proliferation effect of gefitinib in both lung adenocarcinoma PC9 and H1299 cells, whereas miR-4513 increased cells' resistance to gefitinib. Our findings suggest that miR-608 and miR-4513 SNPs are independent candidate biomarkers to predict lung adenocarcinoma patients' survival after EGFR-TKIs treatment. These miRNAs and polymorphisms provide clinical potential in patient-tailored treatment decision-making.

The Association of rs2114358 in the miR-1206 Polymorphism to Chronic Myeloid Leukemia

INTRODUCTION

Association studies with factor candidates have advised that single nucleotide polymorphisms (SNPs) could also be related to CML progression and to the response to medical care. Genetic variation in miR-1206 of both derived and neighborhood SNPs process genes will contribute to the predisposition to cancer. The role of those with the risk of CML has not been extensively studied. Therefore, the aim of this study was to evaluate whether polymorphisms in rs2114358 in pre-miRNAs process genes contribute to the risk of CML.

METHODS

A cross-sectional study was conducted during the period of March 2016 to October 2017 in Khartoum state teaching hospitals. The study population included a total of 420 patients who were previously diagnosed of having CML and 220 cancer-free controls of both gender and were of the same age range. Peripheral blood and bone marrow aspiration samples were collected from patients (254 males, 166 females; median age 58.5 years, range from less than 50 and above 50 years old) and investigated after written informed consent was obtained. Patients were in chronic phase (n=212), accelerated phase (n=125), and blast (n=83). All the patients were under treatment using chemotherapy regiments. The rs2114358 SNP in pre-miRNA was selected for genotyping.

RESULTS

The genotyping success rate was 98.3%. Genotype frequencies of the derived SNP and the neighborhood rs2114358 of miR-1206 compared to the controls were significantly different under Hardy-Weinberg Equilibrium (P=0.0001 and 0.0001 respectively). Significant differences were found in allele distributions of this SNP (P<0.01 and P<0.01). In total, the derived variant C allele of rs2114358 (OR=0.168, 95% CI=0.13-0.22) and G allele of neighborhood rs2114358 (OR=0.561, 95% CI=0.44-0.72) in patients' group were associated with an increased risk of CML compared to a control group. Patients with rs2114358 CC genotype (P = 0.0001) or TC (P = 0.0001) and the neighborhood rs2114358 GA genotype (P = 0.0460) or GG (P = 0.0093) were obviously much higher than that of the TT and AA genotype's patients.

CONCLUSION

In conclusion, we discovered the association of SNP rs2114358 in miR-1206 with the risk of CML patients, though more investigations are still required to understand the regulative mechanisms of this miR SNP with the target genes resulting in its dysregulation.

Non-Coding RNAs and Resistance to Anticancer Drugs in Gastrointestinal Tumors

Non-coding RNAs are important regulators of gene expression and transcription. It is well established that impaired non-coding RNA expression especially the one of long non-coding RNAs and microRNAs is involved in a number of pathological conditions including cancer. Non-coding RNAs are responsible for the development of resistance to anticancer treatments as they regulate drug resistance-related genes, affect intracellular drug concentrations, induce alternative signaling pathways, alter drug efficiency via blocking cell cycle regulation, and DNA damage response. Furthermore, they can prevent therapeutic-induced cell death and promote epithelial-mesenchymal transition (EMT) and elicit non-cell autonomous mechanisms of resistance. In this review, we summarize the role of non-coding RNAs for different mechanisms resulting in drug resistance (e.g., drug transport, drug metabolism, cell cycle regulation, regulation of apoptotic pathways, cancer stem cells, and EMT) in the context of gastrointestinal cancers.

The SNPs in pre-miRNA are related to the response of capecitabine-based therapy in advanced colon cancer patients

The single nucleotide polymorphisms (SNPs) in the microRNA precursor (pre-miRNA) may modulate the posttranscriptional regulation of gene expression and explain individual sensitivity to chemotherapy. Here we investigated the correlation between 23 SNPs in the pre-miRNA and the efficacy of capecitabine-based chemotherapy in 274 advanced colon cancer patients. Statistical analysis indicated that much more patients with rs744591 A/C(48.03%), C/C (53.45%) or C allele (49.73%) responded to the chemotherapy than those with the A/A genotype (33.71%). The response rates of rs745666 G/C heterozygous patients (35.25%) and C allele carriers (39.69%) were apparently less than that of the G/G homozygous patients (56.25%). Moreover, three SNPs rs2114358, rs35770269, and rs73239138 were significantly associated with the occurrence of side effects of chemotherapy. The patients with rs2114358 C allele (OR = 2.016) or rs35770269 T allele (OR = 2.299) were much more prone to endure adverse events. However, the incidence of side effect was lower in the patients carrying rs73239138 A allele than those with G/G genotype (OR = 0.500). Our findings demonstrate that genetic variations in pre-miRNA may influence the efficacy of capecitabine-based chemotherapy in advanced colon cancer patients.

Functional genetic variants of XRCC4 and ERCC1 predict survival of gastric cancer patients treated with chemotherapy by regulating the gene expression

DNA repair protects genomic integrity and may modulate chemotherapy efficacy. Few large-scale studies have evaluated predictive roles of genetic variants of DNA repair genes in survival of Chinese gastric cancer (GCa) patients treated with chemotherapy. Here, we assessed the roles of 35 single nucleotide polymorphisms (SNPs) in DNA repair genes in survival of 1002 GCa patients, of whom 694 received chemotherapy and 308 did not. Among patients receiving chemotherapy, the ERCC1 rs2298881A allele was associated with a better survival [hazards ratio (HR) = 0.82, 95% confidence interval (CI) = 0.69-0.98; P = 0.03], whereas two XRCC4 SNPs were associated with a worse survival (HR = 1.26, 95% CI = 1.03-1.54 for the rs10040363G allele, P = 0.02; and HR = 1.30, 95% CI = 1.06-1.59 for the rs2075685T allele, P = 0.01). These three SNPs were unique survival predictors for patients treated with chemotherapy (P < 0.05 for all) but not for patients without chemotherapy (P > 0.05 for all), suggesting that they modulated chemotherapy efficacy. Patients who received chemotherapy and had haplotypes with at least one death-risk allele in XRCC4 had a poor survival, and the trend for an increase in the number of death-risk alleles adversely affecting the survival was also observed in an allelic dose-dependent manner (P_trend  = 0.001). Further functional analysis revealed that the death-risk alleles up-regulated the gene expression, leading to a worse survival as suggested by our meta-analysis pooling both mRNA microarray data from the GEO database and published data (ERCC1: HR = 1.31 [1.08-1.58]; P = 0.006). These functional genetic variants may independently or jointly affect survival in chemotherapy-treated GCa patients by modulating the gene expression in the tumors.