MiR-21 upregulation induced by promoter zone histone acetylation is associated with chemoresistance to gemcitabine and enhanced malignancy of pancreatic cancer cells

Mechanistic and therapeutic perspectives of miRNA-PTEN signaling axis in cancer therapy resistance

Cancer, being one of the most lethal illnesses, presents an escalating clinical dilemma on a global scale. Despite significant efforts and advancements in cancer treatment over recent decades, the persistent challenge of resistance to traditional chemotherapeutic agents and/or emerging targeted drugs remains a prominent issue in the field of cancer therapies. Among the frequently inactivated tumor suppressor genes in cancer, phosphatase and Tensin Homolog (PTEN) stands out, and its decreased expression may contribute to the emergence of therapeutic resistance. MicroRNAs (miRNAs), characterized by their short length of 22 nucleotides, exert regulatory control over target mRNA expression by binding to complementary sequences. Recent findings indicate that microRNAs play varied regulatory roles, encompassing promotion, suppression, and dual functions on PTEN, and their aberration is implicated in heightened resistance to anticancer therapies. Significantly, recent research has revealed that competitive endogenous RNAs (ceRNAs) play a pivotal role in influencing PTEN expression, and the regulatory network involving circRNA/lncRNA-miRNA-PTEN is intricately linked to resistance in various cancer types to anticancer therapies. Finally, our findings showcase that diverse approaches, such as herbal medicine, small molecule inhibitors, low-intensity ultrasound, and engineered exosomes, can effectively overcome drug resistance in cancer by modulating the miRNA-PTEN axis.

The Multifaceted Role of miR-21 in Pancreatic Cancers

With the lack of specific signs and symptoms, pancreatic ductal adenocarcinoma (PDAC) is often diagnosed at late metastatic stages, resulting in poor survival outcomes. Among various biomarkers, microRNA-21 (miR-21), a small non-coding RNA, is highly expressed in PDAC. By inhibiting regulatory proteins at the 3' untranslated regions (UTR), miR-21 holds significant roles in PDAC cell proliferation, epithelial-mesenchymal transition, angiogenesis, as well as cancer invasion, metastasis, and resistance therapy. We conducted a systematic search across major databases for articles on miR-21 and pancreatic cancer mainly published within the last decade, focusing on their diagnostic, prognostic, therapeutic, and biological roles. This rigorous approach ensured a comprehensive review of miR-21's multifaceted role in pancreatic cancers. In this review, we explore the current understandings and future directions regarding the regulation, diagnostic, prognostic, and therapeutic potential of targeting miR-21 in PDAC. This exhaustive review discusses the involvement of miR-21 in proliferation, epithelial-mesenchymal transition (EMT), apoptosis modulation, angiogenesis, and its role in therapy resistance. Also discussed in the review is the interplay between various molecular pathways that contribute to tumor progression, with specific reference to pancreatic ductal adenocarcinoma.

Emerging role of pancreatic stellate cell-derived extracellular vesicles in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer that is characterised by a prominent collagenous stromal reaction/desmoplasia surrounding tumour cells. Pancreatic stellate cells (PSCs) are responsible for the production of this stroma and have been shown to facilitate PDAC progression. Recently, extracellular vesicles (EVs), in particular, small extracellular vesicles (exosomes) have been a topic of interest in the field of cancer research for their emerging roles in cancer progression and diagnosis. EVs act as a form of intercellular communication by carrying their molecular cargo from one cell to another, regulating functions of the recipient cells. Although the knowledge of the bi-directional interactions between the PSCs and cancer cells that promote disease progression has advanced significantly over the past decade, studies on PSC-derived EVs in PDAC are currently rather limited. This review provides an overview of PDAC, pancreatic stellate cells and their interactions with cancer cells, as well as the currently known role of extracellular vesicles derived from PSCs in PDAC progression.

Tumor-derived miRNAs as tumor microenvironment regulators for synergistic therapeutic options

MicroRNAs (miRNAs) are a class of non-coding RNAs that perform post-transcriptional gene regulation. This review focuses on the role of tumor cell-derived miRNAs in the regulation of the tumor microenvironment (TME) via receptor cell recoding, including angiogenesis, expression of immunosuppressive molecules, formation of radiation resistance, and chemoresistance. Furthermore, we discuss the potential of these molecules as adjuvant therapies in combination with chemotherapy, radiotherapy, or immunotherapy, as well as their advantages as efficacy predictors for personalized therapy. MiRNA-based therapeutic agents for tumors are currently in clinical trials, and while challenges remain, additional research on tumor-derived miRNAs is warranted, which may provide significant clinical benefits to cancer patients.

Emerging roles of long noncoding RNAs in chemoresistance of pancreatic cancer

Pancreatic cancer is one of the most common causes of cancer death in the world due to the lack of early symptoms, metastasis occurrence and chemoresistance. Therefore, early diagnosis by detection of biomarkers, blockade of metastasis, and overcoming chemoresistance are the effective strategies to improve the survival of pancreatic cancer patients. Accumulating evidence has revealed that long noncoding RNA (lncRNA) and circular RNAs (circRNAs) play essential roles in modulating chemosensitivity in pancreatic cancer. In this review article, we will summarize the role of lncRNAs in drug resistance of pancreatic cancer cells, including HOTTIP, HOTAIR, PVT1, linc-ROR, GAS5, UCA1, DYNC2H1-4, MEG3, TUG1, HOST2, HCP5, SLC7A11-AS1 and CASC2. We also highlight the function of circRNAs, such as circHIPK3 and circ_0000284, in regulation of drug sensitivity of pancreatic cancer cells. Moreover, we describe a number of compounds, including curcumin, genistein, resveratrol, quercetin, and salinomycin, which may modulate the expression of lncRNAs and enhance chemosensitivity in pancreatic cancers. Therefore, targeting specific lncRNAs and cicrRNAs could contribute to reverse chemoresistance of pancreatic cancer cells. We hope this review might stimulate the studies of lncRNAs and cicrRNAs, and develop the new therapeutic strategy via modulating these noncoding RNAs to promote chemosensitivity of pancreatic cancer cells.

Potential Role of Exosomes in the Chemoresistance to Gemcitabine and Nab-Paclitaxel in Pancreatic Cancer

In recent years, a growing number of studies have evaluated the role of exosomes in pancreatic ductal adenocarcinoma cancer (PDAC) demonstrating their involvement in a multitude of pathways, including the induction of chemoresistance. The aim of this review is to present an overview of the current knowledge on the role of exosomes in the resistance to gemcitabine and nab-paclitaxel, which are two of the most commonly used drugs for the treatment of PDAC patients. Exosomes are vesicular cargos that transport multiple miRNAs, mRNAs and proteins from one cell to another cell and some of these factors can influence specific determinants of gemcitabine activity, such as the nucleoside transporter hENT1, or multidrug resistance proteins involved in the resistance to paclitaxel. Additional mechanisms underlying exosome-mediated resistance include the modulation of apoptotic pathways, cellular metabolism, or the modulation of oncogenic miRNA, such as miR-21 and miR-155. The current status of studies on circulating exosomal miRNA and their possible role as biomarkers are also discussed. Finally, we integrated the preclinical data with emerging clinical evidence, showing how the study of exosomes could help to predict the resistance of individual tumors, and guide the clinicians in the selection of innovative therapeutic strategies to overcome drug resistance.

Epigenetic Regulation Towards Acquired Drug Resistance in Cancer

Therapy resistance remains the most challenging obstacle in cancer treatment. Substantial efforts and evidences have accumulated over decades suggesting not only genetic but non-genomic mechanisms underlying this adaptation of tumor cells. Alterations in epigenome can have a fundamental effect on cellular functions and response to stresses like anticancer therapy. This chapter discusses the principal mechanisms by which epigenetic modifications in the genome and transcriptome aid tumor cells toward acquisition of resistance to chemotherapy.

Challenges for Better Diagnosis and Management of Pancreatic and Biliary Tract Cancers Focusing on Blood Biomarkers: A Systematic Review

Simple Summary

Pancreatic and biliary tract cancers are malignant tumors that have a very poor prognosis and are resistant to chemotherapy. The later a cancer is detected, the worse the prognosis becomes; therefore, early detection is important. Biomarkers are physiological indices that serve as a guide to indicate the presence or absence of a certain disease, or its progression. The purpose of our research is to summarize previously reported biomarkers for the diagnosis and prognosis of pancreatic and biliary tract cancers.

Abstract

Background: pancreatic cancer (PCa) and biliary tract cancer (BTC) are cancers with a poor prognosis and few effective treatments. One of the reasons for this is late detection. Many researchers are tackling to develop non-invasive biomarkers for cancer, but few are specific for PCa or BTC. In addition, genetic abnormalities occur in cancer tissues, which ultimately affect the expression of various molecules. Therefore, it is important to identify molecules that are altered in PCa and BTC. For this systematic review, a systematic review of Medline and Embase to select biomarker studies of PCa and BTC patients was conducted. Results: after reviewing 72 studies, 79 biomarker candidates were identified, including 22 nucleic acids, 43 proteins, and 14 immune cell types. Of the 72 studies, 61 examined PCa, and 11 examined BTC. Conclusion: PCa and BTC are characterized by nucleic acid, protein, and immune cell profiles that are markedly different from those of healthy subjects. These altered molecules and cell subsets may serve as cancer-specific biomarkers, particularly in blood. Further studies are needed to better understand the diagnosis and prognosis of PCa and BTC.

Role of epithelial-mesenchymal transition in chemoresistance in pancreatic ductal adenocarcinoma

Pancreatic cancer (PC) is the seventh leading cause of cancer death worldwide. The vast majority of patients who have PC develop metastases, resulting in poor treatment effects. Although great progress in therapeutic approaches has been achieved in recent decades, extensive drug resistance still persists, representing a major hurdle to effective anticancer therapy for pancreatic ductal adenocarcinoma (PDAC). Therefore, there is an urgent need to better understand the drug resistance mechanisms and develop novel treatment strategies to improve patient outcomes. Numerous studies suggest that chemoresistance is closely related to epithelial-mesenchymal transition (EMT) of PDAC cells. Thus, this article summarizes the impact of EMT on PDAC from the perspective of chemotherapy resistance and discusses the possible novel applications of EMT inhibition to develop more effective drugs against PDAC.

Non-coding RNAs in pancreatic ductal adenocarcinoma: New approaches for better diagnosis and therapy

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies with a 5-year survival rate less than 8%, which has remained unchanged over the last 50 years. Early detection is particularly difficult due to the lack of disease-specific symptoms and a reliable biomarker. Multimodality treatment including chemotherapy, radiotherapy (used sparingly) and surgery has become the standard of care for patients with PDAC. Carbohydrate antigen 19-9 (CA 19-9) is the most common diagnostic biomarker; however, it is not specific enough especially for asymptomatic patients. Non-coding RNAs are often deregulated in human malignancies and shown to be involved in cancer-related mechanisms such as cell growth, differentiation, and cell death. Several micro, long non-coding and circular RNAs have been reported to date which are involved in PDAC. Aim of this review is to discuss the roles and functions of non-coding RNAs in diagnosis and treatments of PDAC.

MicroRNAs: potential biomarkers for diagnosis and prognosis of different cancers

A thorough understanding of the tumor environment and underlying genetic factors helps in the better formulation of cancer management strategies. Availability of efficient diagnostic and prognostic biomarkers facilitates early detection and progression of the disease. MicroRNAs affect different biological processes participating in tumorigenesis through regulation of their target genes. An expanding list of unique RNAs and understanding of their regulatory role has opened up a new field in cancer research. Based on a comprehensive literature search, we identified 728 miRNAs dysregulated in sixteen cancer types namely bladder cancer (BC), breast cancer (BrC), cervical cancer (CC), colorectal cancer (CRC), esophageal cancer (EC), endometrial cancer (EnC), gastric cancer (GC), hepatocellular cancer (HCC), head and neck squamous cell cancer (HNSCC), lung cancer (LC), ovarian cancer (OC), pancreatic cancer (PC), prostate cancer (PrC), renal cell cancer (RCC), skin cancer (SC), and thyroid cancer (TC). Expression of 43 miRNAs was either upregulated or downregulated in six or more of these cancers. Finally, seven miRNAs namely mir-18a, mir-21, mir-143/145, mir-210, mir-218, mir-221, showing maximum dysregulation, either up- or down-regulation in the majority of cancers, were selected for a detailed presentation of their expression and evaluation of their potential as biomarkers in the diagnosis and prognosis of different cancers.

Prognostic and predictive factors in pancreatic cancer

Pancreatic cancer is one of the leading causes of cancer death worldwide. Its high mortality rate has remained unchanged for years. Radiotherapy and surgery are considered standard treatments in early and locally advanced stages. Chemotherapy is the only option for metastatic patients. Two treatment regimens, i. e. the association of 5-fluorouracil- irinotecan-oxaliplatin (FOLFIRINOX) and the association of nab-paclitaxel with gemcitabine, have been shown to improve outcomes for metastatic pancreatic adenocarcinoma patients. However, there are not standardized predictive biomarkers able to identify patients who benefit most from treatments. CA19-9 is the most studied prognostic biomarker, its predictive role remains unclear. Other clinical, histological and molecular biomarkers are emerging in prognostic and predictive settings. The aim of this review is to provide an overview of prognostic and predictive markers used in clinical practice and to explore the most promising fields of research in terms of treatment selection and tailored therapy in pancreatic cancer.

miRNA and Gene Expression in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains a challenging disease that is mostly diagnosed late in the course of the illness. Unlike other cancers in which measurable successes have been achieved with traditional chemotherapy, targeted therapy, and, recently, immunotherapy, PDAC has proved to be poorly responsive to these treatments, with only marginal to modest incremental benefits using conventional cytotoxic therapy. There is, therefore, a great unmet need to develop better therapies based on improved understanding of biology and identification of predictive and prognostic biomarkers that would guide therapy. miRNAs are small noncoding RNAs that regulate the expression of some key genes by targeting their 3'-untranslated mRNA region. Aberrant expression of miRNAs has been linked to the development of various malignancies, including PDAC. A series of miRNAs have been identified as potential tools for early diagnosis, prediction of treatment response, and prognosis of patients with PDAC. In this review, we present a summary of the miRNAs that have been studied in PDAC in the context of disease biology.

Exposure to ultrafine particulate matter induces NF-κβ mediated epigenetic modifications

Exposure to ultrafine particulate matter (PM0.1) is positively associated with the etiology of different acute and chronic disorders; however, the in-depth biological imprints that link these submicron particles with the disturbances in the epigenomic machinery are not well defined. Earlier, we showed that exposure to these particles causes significant disturbances in the mitochondrial machinery and triggers PI-3-kinase mediated DNA damage responses. In the present study, we aimed to further understand the epigenomic insights of the ultrafine PM exposure. The higher levels of intracellular reactive oxygen species and depleted Nrf-2 in ultrafine PM exposed cells reconfirmed its potential to induce oxidative stress. Importantly, the observed increase in the levels of NF-κβ and associated cytokines among exposed cells suggested the activation of NF-κβ mediated inflammatory loop which potentially serves as a platform for initiating epigenetic insinuations. This fact was strongly supported by the altered miRNA expression profile of the ultrafine PM exposed cells. These NF-κβ induced miRNA alterations were also found to be associated with other epigenetic targets as the exposed cells showed higher expression levels of DNA methyltransferases which positively corresponded with the global changes in DNA methylation levels. Upon further analysis, significant alterations in histone code were also reported in ultrafine PM exposed cells. Conclusively our results suggested that NF-κβ acts as an inflammatory switch that possesses the potential to induce genome-wide epigenetic modification upon ultrafine PM exposure.

miRNA Predictors of Pancreatic Cancer Chemotherapeutic Response: A Systematic Review and Meta-Analysis

BACKGROUND

pancreatic cancer (PC) has increasing incidence and mortality in developing countries, and drug resistance is a significant hindrance to the efficacy of successful treatment. The objective of this systematic review and meta-analysis was to evaluate the association between miRNAs and response to chemotherapy in pancreatic cancer patients.

METHODS

the systematic review and meta-analysis was based on articles collected from a thorough search of PubMed and Science Direct databases for publications spanning from January 2008 to December 2018. The articles were screened via a set of inclusion and exclusion criteria based on the preferred reporting items for systematic review and meta-analysis (PRISMA) guidelines. Data was extracted, collated and tabulated in MS Excel for further synthesis. Hazard ratio (HR) was selected as the effect size metric to be pooled across studies for the meta-analysis, with the random effects model being applied. Subgroup analysis was also conducted, and the presence of publication bias in the selected studies was assessed. Publication bias of the included studies was quantified.

FINDINGS

of the 169 articles screened, 43 studies were included in our systematic review and 13 articles were included in the meta-analysis. Gemcitabine was observed to be the principal drug used in a majority of the studies. A total of 48 miRNAs have been studied, and 18 were observed to have possible contributions to chemoresistance, while 15 were observed to have possible contributions to chemosensitivity. 41 drug-related genetic pathways have been identified, through which the highlighted miRNA may be affecting chemosensitivity/resistance. The pooled HR value for overall survival was 1.603; (95% Confidence Interval (CI) 1.2-2.143; p-value: 0.01), with the subgroup analysis for miR-21 showing HR for resistance of 2.061; 95% CI 1.195-3.556; p-value: 0.09.

INTERPRETATION

our results highlight multiple miRNAs that have possible associations with modulation of chemotherapy response in pancreatic cancer patients. Further studies are needed to discover the molecular mechanisms underlying these associations before they can be suggested for use as biomarkers of response to chemotherapeutic interventions in pancreatic cancer.

Analysis of promoter methylation and epigenetic regulation of miR-32 in colorectal cancer cells

MicroRNA-32 (miR-32) is upregulated in colorectal cancer (CRC) tissues; its overexpression leads to increased cell proliferation, migration and invasion, as well as reduced apoptosis of CRC cells, at least partly by inhibiting the target gene phosphatase and tensin homolog. However, the mechanisms of its upregulation have remained elusive. In the present study, the effects of methylation and acetylation on the expression of miR-32 were investigated. The promoter methylation status of miR-32 in the CRC cell lines HT-29 and HCT-116 and the normal colonic epithelial cell line NCM460 was investigated by bisulfate sequencing polymerase chain reaction (BSP). The potential role of methylation and histone acetylation in the regulation of miR-32 expression in CRC cells was investigated using the demethylation reagent 5-aza-2'-deoxycytidine (5-Aza-dC), the histone deacetylase inhibitor trichostatin A (TSA) and transfection of DNA methyltransferase 1 (DNMT1) overexpression plasmid. BSP revealed that CpG sites in the miR-32 promoter region of CRC and normal colonic epithelial cells were all hypomethylated, with methylation rates of 0.12, 1.14 and 0.64% in HCT-116, HT-29 and NCM460 cells, respectively. Treatment with 5-Aza-dC and/or TSA and transfection with DNMT1 plasmid did not significantly alter the expression of miR-32. Therefore, the present results suggest that methylation and histone acetylation do not affect miR-32 expression in CRC cells.

The role and mechanisms of action of microRNAs in cancer drug resistance

MicroRNAs (miRNAs) are small non-coding RNAs with a length of about 19–25 nt, which can regulate various target genes and are thus involved in the regulation of a variety of biological and pathological processes, including the formation and development of cancer. Drug resistance in cancer chemotherapy is one of the main obstacles to curing this malignant disease. Statistical data indicate that over 90% of the mortality of patients with cancer is related to drug resistance. Drug resistance of cancer chemotherapy can be caused by many mechanisms, such as decreased antitumor drug uptake, modified drug targets, altered cell cycle checkpoints, or increased DNA damage repair, among others. In recent years, many studies have shown that miRNAs are involved in the drug resistance of tumor cells by targeting drug-resistance-related genes or influencing genes related to cell proliferation, cell cycle, and apoptosis. A single miRNA often targets a number of genes, and its regulatory effect is tissue-specific. In this review, we emphasize the miRNAs that are involved in the regulation of drug resistance among different cancers and probe the mechanisms of the deregulated expression of miRNAs. The molecular targets of miRNAs and their underlying signaling pathways are also explored comprehensively. A holistic understanding of the functions of miRNAs in drug resistance will help us develop better strategies to regulate them efficiently and will finally pave the way toward better translation of miRNAs into clinics, developing them into a promising approach in cancer therapy.

Dysregulation of key microRNAs in pancreatic cancer development

Pancreatic cancer (PC) is mentioned as one of the fourth major cause of cancer-related deaths and also is considered as one of the most malignancies worldwide. Sadly, widely metastasis is frequently observed at the time of PC detection and there are, thereby, almost poor prognosis and ineffective treatment in PC patients. microRNAs (miRNAs), a group of short non-coding RNAs, regulate various cellular and developmental mechanisms, such as cell growth, proliferation, apoptosis, differentiation and angiogenesis. Also, they have essential roles even on the progression of different human and animal diseases. In recent years, extensive studies confirmed the important role of miRNAs in various steps of PC developments, including; tumor initiation, invasion and metastasis, which can use valuably for cancer detection, prognosis and therapy. Therefore, the present study reviewed the new recent investigations in miRNAs involvement in the biology of PC associated with their clinical implications.

miR-125a-3p is responsible for chemosensitivity in PDAC by inhibiting epithelial-mesenchymal transition via Fyn

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers and resistance to cytotoxic chemotherapy is the major cause of mortality in PDAC patients. miR-125a-3p was found to be down-regulated in PDAC cells; however, the function of miR-125a-3p in PDAC has been elusive. Here, we explored the role of miR-125a-3p in chemosensitivity in PDAC cells.

METHODS

We used qRT-PCR to detect miR-125a-3p expression in two PDAC cell lines. And we measured cell viability and apoptosis by MTT assay and flow cytometry, respectively. Scratch wound healing assay and transwell invasion assay were used to test the effects of miR-125a-3p and Fyn on cell EMT process. In addition, we validated the interaction of miR-125a-3p and Fyn by dual luciferase reporter assay. qRT-PCR and western blot were used to detect the mRNA and protein expressions of E-cadhrein, N-cadhrein, Snail and Fyn.

RESULTS

We found that miR-125a-3p was down-regulated in a time-dependent manner following treatment with gemcitabine in PDAC cells. Meanwhile, we found that overexpression of miR-125a-3p significantly increased chemosensitivity to gemcitabine and suppressed epithelial-mesenchymal transition (EMT) of PDAC cells. Mechanistically, miR-125a-3p directly targeted Fyn and decreased the expression of Fyn that functions to promote EMT process in PDAC. Furthermore, overexpression of Fyn could partially reverse the effects of miR-125a-3p on chemosensitivity to gemcitabine.

CONCLUSION

Our study is the first to show that miR-125a-3p is responsible for chemosensitivity in PDAC and could inhibit epithelial-mesenchymal transition by directly targeting Fyn. This provides a novel potential therapeutic strategy to overcome chemoresistance in PDAC.

miR-21 Is Overexpressed in Hydatidiform Mole Tissues and Promotes Proliferation, Migration, and Invasion in Choriocarcinoma Cells

OBJECTIVE

The aims of this study were to make clear whether miR-21 was dysregulated in hydatidiform mole (HM) tissues and choriocarcinoma (CCA) cells, to elucidate whether aberrant miR-21 expression would affect the function of CCA cells, and to find out whether there was a relationship between miR-21 and AKT, PDCD4, and PTEN in CCA cells.

METHODS

Fresh and formalin-fixed, paraffin-embedded trophoblastic tissues (normal first trimester placentas and HMs) were retrieved from the biobank in the International Peace Maternity and Child Health Hospital, Shanghai Jiao Tong University. Choriocarcinoma JAR and JEG-3 cells were cultured. Expression of miR-21 in trophoblast cells and tissues was examined by quantitative real-time polymerase chain reaction. Location and distribution of miR-21 in trophoblast tissues were determinated by in situ hybridization and fluorescent in situ hybridization. The effect of miR-21 on JAR and JEG-3 cells was tested by miR-21 mimics and inhibitor transfection, followed by cell viability assay, flow cytometric analysis, and Transwell analysis. Interaction between miR-21 and its target genes in CCA cells was verified by quantitative real-time polymerase chain reaction, Western blot, and luciferase report system.

RESULTS

We originally found miR-21 was markedly upregulated in HM tissues compared with normal first trimester placentas. The expression of miR-21 was exclusively confined in trophoblastic layers. Furthermore, we discovered miR-21 was significantly increased in JAR and JEG-3 cells compared with normal primary human trophoblastic cells. Moreover, we demonstrated miR-21 could promote proliferation, migration, and invasion of CCA cells. We furthermore proved miR-21 negatively regulated PDCD4 and PTEN in CCA cells and targeted to PDCD4 3'UTR directly. In addition, we confirmed that miR-21 could activate Akt pathway by phosphorylating Akt at Ser 473.

CONCLUSIONS

Our results suggested miR-21 was responsible for aggressive phenotype of gestational trophoblastic disease and had the potential diagnostic and therapeutic values for gestational trophoblastic neoplasm.

miRNA-21 enhances chemoresistance to cisplatin in epithelial ovarian cancer by negatively regulating PTEN

MicroRNAs (miRNAs) are small non-coding RNAs, 8-23 nucleotides in length, which regulate gene expression at the post-transcriptional level. The present study was performed to analyze the association between microRNA-21 and cisplatin resistance in epithelial ovarian cancer (EOC) SKOV3 and SKOV3/DDP cells. In this experiment, the resistance of SKOV3 and SKOV3/DDP cells to cisplatin was evaluated using the MTT assay. Reverse transcription-quantitative polymerase chain reaction analysis was used to assess miRNA-21 levels and phosphatase and tensin homolog (PTEN) mRNA levels. Western blotting was used to assess PTEN protein levels. miRNA-21 mimics or inhibitors were transfected into SKOV3 and SKOV3/DDP cells. Prior to transfection, higher expression levels of miRNA-21 were observed in SKOV3/DDP cells compared with SKOV3 cells. Following transfection with miRNA-21 mimics, SKOV3 cells demonstrated increased sensitivity to cisplatin compared with negative control cells. Following transfection with the miRNA-21 inhibitor, SKOV3/DDP cells demonstrated decreased sensitivity to cisplatin compared with negative control cells. Furthermore, PTEN mRNA expression levels in SKOV3 cells transfected with miRNA-21 mimics was significantly lower compared with negative control cells. These results suggested that miRNA-21 may regulate cisplatin resistance by negatively targeting PTEN in EOC.

MicroRNA-21 as a prognostic biomarker in patients with pancreatic cancer - A systematic review and meta-analysis

OBJECTIVES

The aim of this systematic review and meta-analysis is to summarize the current knowledge regarding microRNA-21 and to evaluate its prognostic impact in patients with pancreatic cancer.

METHODS

We conducted an electronic literature search to identify all published studies in PubMed/MEDLINE, Scopus and Google Scholar databases from 2000 until August 2016.

RESULTS

A total of 17 studies involving 1471 patients met the inclusion criteria for the quantitative synthesis. The microRNA-21 upregulation was significantly associated with poorer overall survival, disease-free survival, and progression-free survival. The subgroup analysis revealed that microRNA-21 overexpression has a significant higher prognostic value for patients who receive adjuvant chemotherapy. Increased microRNA-21 was associated with a statistically significant higher rate of metastatic lymph nodes and poorly differentiated tumors.

CONCLUSIONS

MicroRNA-21 upregulation in pancreatic cancer is associated with a significantly poorer overall survival, disease-free survival, and progression-free survival. MicroRNA-21 may be a useful prognostic biomarker, allowing stratification for chemotherapy administration, and being a component of precision medicine in patients with pancreatic cancer.

Critical role of HMGA proteins in cancer cell chemoresistance

The high-mobility group A (HMGA) proteins are frequently overexpressed in human malignancies and correlate with the presence of metastases and reduced patient survival. Here, we highlight the main studies evidencing a critical role of HMGA in chemoresistance, mainly by activating Akt signaling, impairing p53 activity, and regulating the expression of microRNAs that target genes involved in the susceptibility of cancer cells to antineoplastic agents. Therefore, these studies account for the association of HMGA overexpression with patient poor outcome, indicating the impairment of HMGA as a fascinating perspective for effectively improving cancer therapy.

Gemcitabine Enhances Kras-MEK-Induced Matrix Metalloproteinase-10 Expression Via Histone Acetylation in Gemcitabine-Resistant Pancreatic Tumor-initiating Cells

OBJECTIVES

Advanced pancreatic ductal adenocarcinoma is resistant to systemic chemotherapy, resulting in a poor prognosis. We previously isolated a human pancreatic tumor-initiating cell line, KMC07, from a patient with acquired resistance to gemcitabine chemotherapy. To improve the anticancer effects of gemcitabine, we investigated the molecular mechanism of KMC07 cells' resistance to gemcitabine.

METHODS

KMC07 cells were treated with gemcitabine, then gene expression and functional analyses performed using microarray, the quantitative polymerase chain reaction, immunoblotting, immunohistochemistry, chromatin immunoprecipitation, and cell transplantation into nude mice.

RESULTS

KMC07 cells, but not BxPC-3, PANC-1, MIA PaCa-2, or AsPC-1 cells, expressed matrix metalloproteinase-10 mRNA, the expression level of which was enhanced by gemcitabine. KMC07 cells were shown to carry a constitutively active Kras mutation, and a MEK inhibitor suppressed matrix metalloproteinase-10 mRNA expression. Gemcitabine enhanced histone H3 acetylation at the matrix metalloproteinase-10 promoter, and a histone acetyltransferase inhibitor reduced gemcitabine-enhanced matrix metalloproteinase-10 mRNA expression. Gemcitabine induced expression of matrix metalloproteinase-10 protein in KMC07-derived pancreatic tumors in vivo.

CONCLUSIONS

We demonstrated constitutive activation of the Kras-MEK matrix metalloproteinase-10 signaling pathway in KMC07 cells that was enhanced by gemcitabine through histone acetylation. Our results may provide novel insights into gemcitabine-based treatment for gemcitabine-resistant pancreatic ductal adenocarcinoma.

MicroRNA Targeted Therapeutic Approach for Pancreatic Cancer

Pancreatic cancer remains the fourth leading cause of cancer-related death in the US and is expected to be the second leading cause of cancer-related death by 2030. Therefore, it is important to better understand the molecular pathogenesis, phenotypes and features of pancreatic cancer in order to design novel molecularly targeted therapies for achieving better therapeutic outcome of patients with pancreatic cancer. Recently, the roles of microRNAs (miRNAs) in the development and progression of pancreatic cancer became a hot topic in the scientific community of pancreatic cancer research. By conducting miRNA expression profiling, the aberrant expression of miRNAs was revealed in the serum and in cancer tissues from patients with pancreatic cancer. These aberrantly expressed miRNAs are critically correlated with the disease stage, drug resistance, and survival of pancreatic cancer patients. Hence, targeting these tiny molecules, the specific miRNAs, could provide an efficient and optimal approach in the therapy of pancreatic cancer. Indeed, the pre-clinical and in vivo experiments showed that nanoparticle delivery of synthetic oligonucleotides or treatment with natural agents could be useful to modulate the expression of miRNAs and thereby inhibit pancreatic cancer growth and progression, suggesting that targeting miRNAs combined with conventional anti-cancer therapeutics could be a novel therapeutic strategy for increasing drug sensitivity and achieving better therapeutic outcome of patients diagnosed with pancreatic cancer.

Circulating Blood-Borne microRNAs as Biomarkers in Solid Tumors

One of the major challenges in cancer research is the identification of stable biomarkers that could be routinely measured in easily accessible samples. Human blood and other body fluids represent rich sources for the identification of novel biomarkers. It is apparent that the availability of these biomarkers would improve an early detection of asymptomatic disease and the clinical management of cancer. MicroRNAs have been described to be present in various types of body fluids including cell-free serum and plasma. These days, the involvement of microRNAs in molecular pathology of cancer is well established. Moreover, it seems that these molecules could be optimal noninvasive biomarkers owing to their high stability under storage and handling conditions and high sensitivity and specificity in various diseases. To date, more than 100 circulating microRNAs with the potential to serve as novel diagnostic, prognostic, or predictive biomarkers for different types of cancers have been identified, and this number is still increasing. However, there are major discrepancies in the findings by different research groups, and few commonly altered microRNAs have been reported in these studies. Further studies on large cohorts using uniform methodology are warranted to establish the clinical applicability of circulating microRNAs for solid tumors. Here, we summarize the tumor-specific profiles of blood-borne microRNAs and discuss their potential utility for personalized medicine of solid tumors.

MicroRNAs as promising biomarkers for tumor-staging: evaluation of MiR21 MiR155 MiR29a and MiR92a in predicting tumor stage of rectal cancer

OBJECTIVE

In this study, tumor-stage predictive abilities of miR21, miR155, miR29a and miR92a were evaluated in rectal cancer (RC).

METHODS

Expression of miR21, miR155, miR29a and miR92a was detected and quantitated in tumor tissue and in adjacent normal tissue from 40 patients by TaqMan MicroRNA assay.

RESULTS

Significant overexpression of miR21, miR155, miR29a and miR92a was observed in RC tissues. While high expression of miR21, miR155 and miR29a in N1-2 and C-D stages presented a potential correlation with N and Duke stages, partial correlation analysis suggested that only miR155 rather than miR21 and miR29a played a greater influencing role. Receiver operating characteristics (ROC) curve analysis showed that miR155 could discriminate N0 from N1-2 with 85.0% sensitivity and 85.0% specificity, N2 from N0-1 with 90.0% sensitivity and 96.7% specificity, and C-D stage from A-B stage with 81.0% sensitivity and 84.2% specificity.

CONCLUSIONS

Increase in expression of miR155 might represent a novel predictor for RC N and Dukes staging.

Associations between single nucleotide polymorphisms of COX-2 and MMP-2 genes and colorectal cancer susceptibility in the Saudi population

BACKGROUND

It has been reported that COX-2 expression is associated with MMP-2 expression in thyroid and breast cancers, suggesting that MMPs are linked to COX-2-mediated carcinogenesis. Several polymorphisms within the MMP2 promoter region have been reported in cases with oncogenesis and tumor progression, especially in colorectal carcinogenesis.

MATERIALS AND METHODS

This research evaluated risk of association of the SNPs, including genes for COX-2 (A/G transition at +202) and MMP-2 (C/T transition at-1306), with colorectal cancer in 125 patients and 125 healthy controls.

RESULTS AND CONCLUSIONS

Our data confirmed that MMP2 C-1306 T mutations were significantly more common in colon cancer patients than in our control Saudi population; p=0.0121. On the other hand in our study, there was no significant association between genotype distribution of the COX2 polymorphism and colorectal cancer; p=0.847. An elevated frequency of the mutated genotype in the control group as compared to the patients subjects indeed suggested that this polymorphism could decrease risk in the Saudi population. Our study confirmed that the polymorphisms that could affect the expressions of MMP-2 and COX-2 the colon cancer patients were significantly higher than that in the COX-2 negative group. The frequency of individuals with MMP2 polymorphisms in colon cancer patients was higher than individuals with combination of COX2 and MMP2 polymorphisms. Our study confirmed that individuals who carried the polymorphisms that could affect the expressions of COX2 are more susceptible to colon cancer. MMP2 regulatory polymorphisms could be considered as protective; further studies need to confirm the results with more samples and healthy subjects.

miRNAs in pancreatic cancer: therapeutic potential, delivery challenges and strategies

Pancreatic ductal adenocarcinoma (PDAC) is a severe pancreatic malignancy and is predicted to victimize 1.5% of men and women during their lifetime (Cancer statistics: SEER stat fact sheet, National Cancer Institute, 2014). miRNAs have emerged as a promising prognostic, diagnostic and therapeutic tool to fight against pancreatic cancer. miRNAs could modulate gene expression by imperfect base-pairing with target mRNA and hence provide means to fine-tune multiple genes simultaneously and alter various signaling pathways associated with the disease. This exceptional miRNA feature has provided a paradigm shift from the conventional one drug one target concept to one drug multiple target theory. However, in vivo miRNA delivery is not fully realized due to challenges posed by this special class of therapeutic molecules, which involves thorough understanding of the biogenesis and physicochemical properties of miRNA and delivery carriers along with the pathophysiology of the PDAC. This review highlights the delivery strategies of miRNA modulators (mimic/inhibitor) in cancer with special emphasis on PDAC since successful delivery of miRNA in vivo constitutes the major challenge in clinical translation of this promising class of therapeutics.