miR-210 regulates the interaction between pancreatic cancer cells and stellate cells

Downregulation of microRNA-210 inhibits osteosarcoma growth in vitro and in vivo

MicroRNA‑210 (miR‑210), the master hypoxamir, has various roles in the development of certain cancer types. It has been reported that miR‑210 expression was upregulated in patients with osteosarcoma (OS). However, little is known regarding its role in the development of human OS. In the present study, to explore the feasibility of miR‑210 as an effective therapeutic target, miR‑210 inhibitor was transfected into the osteosarcoma cell line MG‑63 cells, and cell proliferation, colony formation, cycle, apoptosis, migration and invasion were assessed. It was found that miR‑210 downregulation significantly suppressed clonogenicity, migration and invasion, as well as induced cell apoptosis, increased the percentage of cells in G1 phrase and decreased the percentage of cells in S phase in vitro. In addition, the effect of miR‑210 on tumor growth was evaluated in vivo. The results indicated that miR‑210 downregulation significantly suppressed tumor growth in nude mouse models. In conclusion, the findings of the present study suggested that miR‑210 is a potential therapeutic agent for the treatment of OS.

What are the macrophages and stellate cells doing in pancreatic adenocarcinoma?

Pancreatic ductal adenocarcinoma is a devastating disease characterized by a dense desmoplastic stroma. Chemo- and radio-therapeutic strategies based on targeting cancer cells have failed in improving the outcome of this cancer suggesting important roles for stroma in therapy resistance. Cells in the tumor stroma have been shown to regulate proliferation, resistance to apoptosis and treatments, epithelial to mesenchymal transition (EMT) and stemness of cancer cells. Stellate cells in their activated state have been thought over the past decade to only have tumor promoting roles. However, recent findings suggest that stellate cells may have protective roles as well. The present review highlights the latest findings on the role of two major components of tumor stroma, pancreatic stellate cells and macrophages, in promoting or inhibiting pancreatic cancer, focused on their effects on EMT and cancer stemness.

PLC-beta 1 regulates the expression of miR-210 during mithramycin-mediated erythroid differentiation in K562 cells

PLC-beta 1 (PLCβ1) inhibits in human K562 cells erythroid differentiation induced by mithramycin (MTH) by targeting miR-210 expression. Inhibition of miR-210 affects the erythroid differentiation pathway and it occurs to a greater extent in MTH-treated cells. Overexpression of PLCβ1 suppresses the differentiation of K562 elicited by MTH as demonstrated by the absence of γ-globin expression. Inhibition of PLCβ1 expression is capable to promote the differentiation process leading to a recovery of γ-globin gene even in the absence of MTH. Our experimental evidences suggest that PLCβ1 signaling regulates erythropoiesis through miR-210. Indeed overexpression of PLCβ1 leads to a decrease of miR-210 expression after MTH treatment. Moreover miR-210 is up-regulated when PLCβ1 expression is down-regulated. When we silenced PKCα by RNAi technique, we found a decrease in miR-210 and γ-globin expression levels, which led to a severe slowdown of cell differentiation in K562 cells and these effects were the same encountered in cells overexpressing PLCβ1. Therefore we suggest a novel role for PLCβ1 in regulating miR-210 and our data hint at the fact that, in human K562 erythroleukemia cells, the modulation of PLCβ1 expression is able to exert an impairment of normal erythropoiesis as assessed by γ-globin expression.

Serum microRNA-210 as a potential noninvasive biomarker for the diagnosis and prognosis of glioma

BACKGROUND

MicroRNA-210 (miR-210) is an oncogenic miRNA previously associated with prognosis in human gliomas, an incurable tumour type of the central nervous system. Here miR-210 was investigated as a potential serum biomarker in the diagnosis and prognosis of glioma.

METHODS

Serum was immediately prepared from blood samples collected from patients with glioma grades I-IV at primary diagnosis (n=136) and healthy controls (n=50) from February 2007 to March 2014 in the Department of Neurosurgery of the First Affiliated Hospital of Wannan Medical College (Wuhu, China). Total RNA was isolated from serum. cDNA was synthesised with primers specific for miR-210 and miR-16-1 (internal control), and quantitative real-time RT-PCR was performed. Results were statistically analysed to determine the role of miR-210 in the diagnosis and prognosis of human glioma patients.

RESULTS

An approximately seven-fold increase in miR-210 expression was detected in serum samples from glioblastoma patients relative to healthy controls. A threshold expression value (2.259) was chosen from receiver operator characteristic curves (ROC), and the low and high miR-210 expression groups were analysed by multivariate Cox proportional hazard regression and Kaplan-Meier analyses. Results revealed an association of high serum miR-210 expression with tumour grade and poor patient outcome (P-values <0.001).

CONCLUSIONS

Serum miR-210 is a promising diagnostic and prognostic biomarker that can be detected in the peripheral blood of patients with glioma.

MIR210 as a potential molecular target to block invasion and metastasis of gastric cancer

The epithelial-mesenchymal transition (EMT) is a process driving invasion, recurrence, and metastasis of gastric cancer, and EMT is triggered by specific physiological factors that arise during tumorigenesis, such as hypoxia. Identifying the molecular mechanisms underlying EMT will potentially yield insight into the pathways fueling cancer recurrence and metastasis and thus, lead to novel molecular targets that will improve treatment of the disease. The microRNA210 (MIR210) is such a candidate molecule mediating EMT in gastric cancer based on a number of observations. First, MIR210 is often highly overexpressed in gastric cancer. Second, MIR210 is a hypoxia-specific miRNA, and its expression is significantly increased in hypoxic environments where EMT develops. Third, MIR210 is regulated by hypoxia inducible factor 1α (HIF-1α), a key transcription factor mediating important tumor associated processes such as EMT and angiogenesis in response to hypoxia during tumorigenesis. Finally, MIR210 has been intriguingly associated with Helicobacterpylori infection, which typically develops in an anaerobic environment and is known to have a causal role in the development of gastric cancer. Although studies have shown that MIR210 is often highly expressed in gastric cancer and associated with specific pathological conditions, functional experiments have not yet been performed to determine the role of MIR210 and downstream mediators in the development and progression of gastric cancer. Here, MIR210 is proposed as a viable molecular target in the treatment of gastric cancer, specifically for the inhibition of invasion and metastasis.

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.

MiR-210 expression reverses radioresistance of stem-like cells of oesophageal squamous cell carcinoma

AIM: To investigate the expression of miR-210 and the role it plays in the cell cycle to regulate radioresistance in oesophageal squamous cell carcinoma (ESCC).

METHODS: MiR-210 expression was evaluated in 37 pairs of ESCC tissues and matched para-tumorous normal oesophageal tissues from surgical patients who had not received neoadjuvant therapy, and in the cells of two novel radioresistant cell lines, TE-1R and Eca-109R, using quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The transient up-regulation of miR-210 expression in TE-1R and Eca-109R cells was studied using liposomes and was confirmed using qRT-PCR. The rate of cell survival after a series of radio-treatment doses was evaluated using the clone formation assay. Flow cytometry was used to detect the changes to the cell cycle patterns due to radiation treatment. RT-PCR and Western blot were used to detect the expression of ataxia telangiectasia mutated (ATM) and DNA dependent protein kinase (DNA-PKcs) after irradiation, and the cell sphere formation assay was used to evaluate the proliferative ability of the cancer stem-like cells.

RESULTS: The level of miR-210 expression was significantly decreased, by 21.3% to 97.2%, with the average being 39.2% ± 16.1%, in the ESCC tissues of most patients (81.1%, 30 of 37 vs patients with high miR-210 expression, P < 0.05). A low level of expression of miR-210 was correlated with a poorly differentiated pathological type (P < 0.01) but was not correlated with the T-stage or lymph node infiltration (both P > 0.05). Early local recurrences (< 18 mo, n = 19) after radiotherapy were significantly related with low miR-210 expression (n = 13, P < 0.05). The level of miR-210 was decreased by approximately 73% (vs TE-1, 0.27 ± 0.10, P < 0.01) in the established radioresistant TE-IR cell line and by 52% (vs Eca-109, 0.48 ± 0.17, P < 0.05) in the corresponding Eca-109R line. Transient transfection with a miR-210 precursor increased the level of miR-210 expression, leading to a significant increase in cell survival after radiotherapy (P < 0.05). Twenty-four hours after radiation, the proportion of pmiR-210 cells in S phase was increased (vs control cells, 30.4% ± 0.4%, and vs untreated TE-1R cells, 23.3% ± 0.7%, P < 0.05 for both). The levels of DNA-PKcs (0.21 ± 0.07) and ATM (0.12 ± 0.03, P < 0.05) proteins were significantly lower in the PmiR-210 cells than in control cells, but no differences were found in the levels of the corresponding mRNAs in the two cell types (P > 0.05 for all). Exogenous miR-210 expression decreased the diameter of pmiR-210 cell spheres (vs control cells, 0.60 ± 0.14, P < 0.05).

CONCLUSION: MiR-210 expression is negatively correlated with the pathological type and the local survival rate after radiotherapy, and high expression of miR-210 may reverse the radioresistance of ESCC stem-like cells.

High-frequency aberrantly methylated targets in pancreatic adenocarcinoma identified via global DNA methylation analysis using methylCap-seq

BACKGROUND

Extensive reprogramming and dysregulation of DNA methylation is an important characteristic of pancreatic cancer (PC). Our study aimed to characterize the genomic methylation patterns in various genomic contexts of PC. The methyl capture sequencing (methylCap-seq) method was used to map differently methylated regions (DMRs) in pooled samples from ten PC tissues and ten adjacent non-tumor (PN) tissues. A selection of DMRs was validated in an independent set of PC and PN samples using methylation-specific PCR (MSP), bisulfite sequencing PCR (BSP), and methylation sensitive restriction enzyme-based qPCR (MSRE-qPCR). The mRNA and expressed sequence tag (EST) expression of the corresponding genes was investigated using RT-qPCR.

RESULTS

A total of 1,131 PC-specific and 727 PN-specific hypermethylated DMRs were identified in association with CpG islands (CGIs), including gene-associated CGIs and orphan CGIs; 2,955 PC-specific and 2,386 PN-specific hypermethylated DMRs were associated with gene promoters, including promoters containing or lacking CGIs. Moreover, 1,744 PC-specific and 1,488 PN-specific hypermethylated DMRs were found to be associated with CGIs or CGI shores. These results suggested that aberrant hypermethylation in PC typically occurs in regions surrounding the transcription start site (TSS). The BSP, MSP, MSRE-qPCR, and RT-qPCR data indicated that the aberrant DNA methylation in PC tissue and in PC cell lines was associated with gene (or corresponding EST) expression.

CONCLUSIONS

Our study characterized the genome-wide DNA methylation patterns in PC and identified DMRs that were distributed among various genomic contexts that might influence the expression of corresponding genes or transcripts to promote PC. These DMRs might serve as diagnostic biomarkers or therapeutic targets for PC.

Molecular mechanisms underlying the role of microRNAs in the chemoresistance of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is an extremely severe disease where the mortality and incidence rates are almost identical. This is mainly due to late diagnosis and limited response to current treatments. The tumor macroenvironment/microenvironment have been frequently reported as the major contributors to chemoresistance in PDAC, preventing the drugs from reaching their intended site of action (i.e., the malignant duct cells). However, the recent discovery of microRNAs (miRNAs) has provided new directions for research on mechanisms underlying response to chemotherapy. Due to their tissue-/disease-specific expression and high stability in tissues and biofluids, miRNAs represent new promising diagnostic and prognostic/predictive biomarkers and therapeutic targets. Furthermore, several studies have documented that selected miRNAs, such as miR-21 and miR-34a, may influence response to chemotherapy in several tumor types, including PDAC. In this review, we summarize the current knowledge on the role of miRNAs in PDAC and recent advances in understanding their role in chemoresistance through multiple molecular mechanisms.

Epigenetics and pancreatic cancer: pathophysiology and novel treatment aspects

An improvement in pancreatic cancer treatment represents an urgent medical goal. Late diagnosis and high intrinsic resistance to conventional chemotherapy has led to a dismal overall prognosis that has remained unchanged during the past decades. Increasing knowledge about the molecular pathogenesis of the disease has shown that genetic alterations, such as mutations of K-ras, and especially epigenetic dysregulation of tumor-associated genes, such as silencing of the tumor suppressor p16(ink4a), are hallmarks of pancreatic cancer. Here, we describe genes that are commonly affected by epigenetic dysregulation in pancreatic cancer via DNA methylation, histone acetylation or miRNA (microRNA) expression, and review the implications on pancreatic cancer biology such as epithelial-mesenchymal transition, morphological pattern formation, or cancer stem cell regulation during carcinogenesis from PanIN (pancreatic intraepithelial lesions) to invasive cancer and resistance development. Epigenetic drugs, such as DNA methyltransferases or histone deactylase inhibitors, have shown promising preclinical results in pancreatic cancer and are currently in early phases of clinical development. Combinations of epigenetic drugs with established cytotoxic drugs or targeted therapies are promising approaches to improve the poor response and survival rate of pancreatic cancer patients.

Multiple functions of hypoxia-regulated miR-210 in cancer

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression post-transcriptionally. miRNAs can be induced by a variety of stresses such as hypoxia, and are involved in diverse biological processes including differentiation, cell proliferation, cell death, and tumorigenesis. Hypoxia, a common feature of tumor microenvironment, can induce a number of miRNAs expression. miRNA-210 (miR-210) is one of the hypoxia-regulated-miRNAs, which has been investigated extensively in cancer. However, paradoxically opposing results were documented regarding whether it is an oncogene or a tumor suppressor, and whether it is a positive or negative prognostic biomarker. In the present review, we focus on the following investigations of miR-210: 1) its functions of as an oncogene, 2) its functions as a tumor suppressor, 3) its functions in mitochondrial metabolism, and finally, the diagnostic and prognostic value of miR-210 in cancer researches.

Aberrant MicroRNAs in Pancreatic Cancer: Researches and Clinical Implications

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with a high rate of mortality and poor prognosis. Numerous studies have proved that microRNA (miRNA) may play a vital role in a wide range of malignancies, including PDAC, and dysregulated miRNAs, including circulating miRNAs, are associated with PDAC proliferation, invasion, chemosensitivity, and radiosensitivity, as well as prognosis. Greater understanding of the roles of miRNAs in PDAC could provide insights into this disease and identify potential diagnostic markers and therapeutic targets. The current review focuses on recent advances with respect to the roles of miRNAs in PDAC and their practical value.

Inflammation and pancreatic cancer: disease promoter and new therapeutic target

Chronic inflammation has a certain impact on the carcinogenesis of the digestive organs. The characteristic tissue structure of pancreatic cancer, desmoplasia, results from inflammatory processes induced by cancer cells and stromal cells. Concerning the progression of pancreatic cancer, recent research has clarified the pivotal role of tumor-stromal interaction, which promotes the development of an invasive phenotype of cancer and provides survival advantages against chemotherapeutic agents or immune surveillance. Tumor stromal cells such as pancreatic stellate cells and immune cells establish a microenvironment that protects cancer cells through complex interactions. The microenvironment of pancreatic cancer acts as a niche for pancreatic cancer stem cells from which therapy-resistance and disease recurrence develop. Inhibition of the stromal functions or restoration of the immune reaction against cancer cells has therapeutic benefits that enhance the efficacy of conventional therapies. Some of the recent advances in this field are now under evaluation in clinical settings, but many problems must be overcome to establish a radical therapy for pancreatic cancer. This review summarizes current knowledge about the tumor-promoting stromal functions, immune system modulation and therapeutic strategies targeting tumor-stromal interactions in pancreatic cancer.

Alteration of the microRNA expression profile during the activation of pancreatic stellate cells

OBJECTIVE. Pancreatic stellate cells (PSCs) play a pivotal role in the pancreatic fibrosis associated with chronic pancreatitis and pancreatic cancer. In response to pancreatic injury or inflammation, PSCs are activated to myofibroblast-like cells. MicroRNA (miRNA) is a small RNA, consisting of 17-25 nucleotides, which targets 3'-untranslated region sequences of mRNA. miRNAs regulate a variety of cell functions such as cell proliferation, differentiation, and carcinogenesis. We examined here whether the miRNA expression profiles are altered during the activation of PSCs. MATERIALS AND METHODS. Rat PSCs were isolated from the pancreas tissue of male Wistar rats. PSCs were activated in vitro by culture in serum-containing medium. miRNAs were prepared from quiescent (day 1) PSCs and culture-activated (day 14) PSCs. Agilent's miRNA microarray containing probes for 680 miRNAs was used to identify differentially expressed miRNAs. Ingenuity Pathway Analysis (IPA) was used for the integrated analysis of altered miRNAs. RESULTS. Upon activation, 42 miRNAs were upregulated (>2.0-fold) and 42 miRNAs were downregulated (<0.5-fold). Upregulated miRNAs included miR-31, miR-143, and miR-221. Downregulated miRNAs included miR-126, miR-146a, and miR-150. IPA revealed the most impacted biological processes including cellular development, cellular growth, and cell movement. Interestingly, IPA identified 22 miRNAs affected both in pancreatic cancer and PSC activation. The top network generated by IPA revealed the interactions of altered miRNAs with signaling pathways such as p38 mitogen-activated protein kinase, extracellular-signal-regulated kinase, and Smad2/3. CONCLUSIONS. Our results suggest a novel role of miRNAs in the activation of PSCs.

Emerging roles of miR-210 and other non-coding RNAs in the hypoxic response

Hypoxia is a key component of the tumor microenvironment and represents a well-documented source of therapeutic failure in clinical oncology. Recent work has provided support for the idea that non-coding RNAs, and in particular, microRNAs, may play important roles in the adaptive response to low oxygen in tumors. Specifically, all published studies agree that the induction of microRNA-210 (miR-210) is a consistent feature of the hypoxic response in both normal and malignant cells. miR-210 is a robust target of hypoxia-inducible factors, and its overexpression has been detected in a variety of diseases with a hypoxic component, including most solid tumors. High levels of miR-210 have been linked to an in vivo hypoxic signature and to adverse prognosis in breast and pancreatic cancer patients. A wide variety of miR-210 targets have been identified, pointing to roles in mitochondrial metabolism, angiogenesis, DNA damage response, apoptosis, and cell survival. Such targets are suspected to affect the development of tumors in multiple ways; therefore, an increased knowledge about miR-210's functions may lead to novel diagnostic and therapeutic approaches in cancer.

MicroRNAs in pancreatic malignancy: progress and promises

Despite progress in recent years, pancreatic cancer still remains a major clinical challenge. Its incidence and mortality rates have been on consistent rise underscoring the critical need for novel diagnostic, prognostic and therapeutic tools for its effective management. Recent studies have demonstrated that microRNAs (miRNAs/miRs) are deregulated in a variety of malignancies, including pancreatic cancer, and play a significant role in the initiation, progression and metastasis. Furthermore, their vital involvement in the therapeutic resistance of cancer has also been established. Hence, there has been enormous interest worldwide in investigating the roles of miRNAs in pancreatic cancer pathogenesis and exploiting their utility for clinical benefit. In this review, we summarize current knowledge on the role of miRNAs in pancreatic cancer and discuss their potential use as diagnostic and prognostic biomarkers, and as novel targets for development of effective therapeutic strategies.

The zinc transporter LIV-1 is a novel regulator of stemness in pancreatic cancer cells

OBJECTIVE

Recent studies have identified the existence a portion of cancer cells, called "cancer stem cells", within the entire cancer tissue. Cancer stem cells harbor highly tumorigenic and chemo-resistant phenotypes, which lead to recurrence or re-growth of the tumor after surgery. The mechanisms that regulate the stemness of cancer cells remain largely unknown. We hypothesized that LIV-1, a zinc transporter, regulates the stemness in pancreatic cancer cells.

MATERIAL AND METHODS

We established two stable Panc-1 pancreatic cancer cell lines in which LIV-1 expression was knocked down by the introduction of siRNA against LIV-1. Expression of cancer stem cell-related molecules was examined by quantitative real-time PCR. Expression of ATP-binding cassette sub-family G member 2 was also determined by flow cytometry. Spheroid culture was performed in low-adhesion coated plates. Cell migration was determined by using a modified 2-chamber migration assay. In vivo tumor formation was assessed in nude mice after the subcutaneous injection of cancer cells. The Agilent's miRNA microarray was used to identify differentially expressed miRNAs.

RESULTS

Knockdown of LIV-1 expression resulted in (i) decreased expression of cancer stem cell-related molecules such as LIN28 and ATP-binding cassette sub-family G member 2, (ii) decreased spheroid-forming ability, (iii) decreased migration, (iv) decreased incidence of tumor formation in nude mice, and (v) upregulation of miR-7 expression.

CONCLUSIONS

Our results suggest that LIV-1 might act as a novel regulator of stemness in pancreatic cancer cells.

Novel therapeutic strategies targeting tumor-stromal interactions in pancreatic cancer

Therapy-resistance and postoperative recurrence are causes of the poor prognosis in pancreatic cancer. Conventional therapies have a limited impact on the control of pancreatic cancer, resulting in the rapid re-growth of the tumor. The indispensable role of tumor-stromal interaction, which acts as a defender of cancer cells and enhances malignant potential, is being uncovered now. For example, specific signaling pathways for desmoplasia induction have been identified, such as sonic hedgehog (Shh) or connective tissue growth factor (CTGF), whose inhibition causes desmoplasia depletion and therapeutic advantages at least in in vivo mouse models of pancreatic cancer. Revolutions in drug delivery methods have led to the establishment of novel chemotherapeutic regimens, with better patient survival. Furthermore, mechanisms of immunosuppression in the pancreatic cancer-bearing host were clarified by the identification of myeloid-derived suppressor cells (MDSCs), which also promote disease progression. Strategies to target these components of the tumor stroma revealed certain anticancer effects in vitro and in vivo, suggesting the possibility of stroma-targeting therapy. Suppression of the stromal cell function increases the sensitivity of pancreatic cancer cells to therapeutic intervention. Further study will clarify the complex nature of the tumor microenvironment, the targeting of which has the potential to improve clinical outcome.

Alteration of pancreatic cancer cell functions by tumor-stromal cell interaction

Pancreatic cancer shows a characteristic tissue structure called desmoplasia, which consists of dense fibrotic stroma surrounding cancer cells. Interactions between pancreatic cancer cells and stromal cells promote invasive growth of cancer cells and establish a specific microenvironment such as hypoxia which further aggravates the malignant behavior of cancer cells. Pancreatic stellate cells (PSCs) play a pivotal role in the development of fibrosis within the pancreatic cancer tissue, and also affect cancer cell function. PSCs induce epithelial-mesenchymal transition and cancer stem cell (CSC)-related phenotypes in pancreatic cancer cells by activating multiple signaling pathways. In addition, pancreatic cancer cells and PSCs recruit myeloid-derived suppressor cells which attenuate the immune reaction against pancreatic cancer cells. As a result, pancreatic cancer cells become refractory against conventional therapies. The formation of the CSC-niche by stromal cells facilitates postoperative recurrence, re-growth of therapy-resistant tumors and distant metastasis. Conventional therapies targeting cancer cells alone have failed to conquer pancreatic cancer, but targeting the stromal cells and immune cells in animal experiments has provided evidence of improved therapeutic responses. A combination of novel strategies altering stromal cell functions could contribute to improving the pancreatic cancer prognosis.