miR-15a enhances the anticancer effects of cisplatin in the resistant non-small cell lung cancer cells

Regulatory miRNAs in cancer cell recovery from therapy exposure and its implications as a novel therapeutic strategy for preventing disease recurrence

The desired outcome of cancer therapies is the eradication of disease. This can be achieved when therapy exposure leads to therapy-induced cancer cell death as the dominant outcome. Theoretically, a permanent therapy-induced growth arrest could also contribute to a complete response, which has the potential to lead to remission. However, preclinical models have shown that therapy-induced growth arrest is not always durable, as recovering cancer cell populations can contribute to the recurrence of cancer. Significant research efforts have been expended to develop strategies focusing on the prevention of recurrence. Recovery of cells from therapy exposure can occur as a result of several cell stress adaptations. These include cytoprotective autophagy, cellular quiescence, a reversable form of senescence, and the suppression of apoptosis and necroptosis. It is well documented that microRNAs regulate the response of cancer cells to anti-cancer therapies, making targeting microRNAs therapeutically a viable strategy to sensitization and the prevention of recovery. We propose that the use of microRNA-targeting therapies in prolonged sequence, that is, a significant period after initial therapy exposure, could reduce toxicity from the standard combination strategy, and could exploit new epigenetic states essential for cancer cells to recover from therapy exposure. In a step toward supporting this strategy, we survey the available scientific literature to identify microRNAs which could be targeted in sequence to eliminate residual cancer cell populations that were arrested as a result of therapy exposure. It is our hope that by successfully identifying microRNAs which could be targeted in sequence we can prevent disease recurrence.

MicroRNAs as the critical regulators of autophagy-mediated cisplatin response in tumor cells

Chemotherapy is one of the most common therapeutic methods in advanced and metastatic tumors. Cisplatin (CDDP) is considered as one of the main first-line chemotherapy drugs in solid tumors. However, there is a high rate of CDDP resistance in cancer patients. Multi-drug resistance (MDR) as one of the main therapeutic challenges in cancer patients is associated with various cellular processes such as drug efflux, DNA repair, and autophagy. Autophagy is a cellular mechanism that protects the tumor cells toward the chemotherapeutic drugs. Therefore, autophagy regulatory factors can increase or decrease the chemotherapy response in tumor cells. MicroRNAs (miRNAs) have a pivotal role in regulation of autophagy in normal and tumor cells. Therefore, in the present review, we discussed the role of miRNAs in CDDP response through the regulation of autophagy. It has been reported that miRNAs mainly increased the CDDP sensitivity in tumor cells by inhibition of autophagy. PI3K/AKT signaling pathway and autophagy-related genes (ATGs) were the main targets of miRNAs in the regulation of autophagy-mediated CDDP response in tumor cells. This review can be an effective step to introduce the miRNAs as efficient therapeutic options to increase autophagy-mediated CDDP sensitivity in tumor cells.

Insight into autophagy in platinum resistance of cancer

Platinum drugs, as a class of widely used chemotherapy agents, frequently appear in the treatment of cancer at different phrases. However, platinum resistance is the major bottleneck of platinum drugs for exerting anti-tumor effect. At present, the mechanism of platinum resistance has been thoroughly explored in terms of drug delivery methods, DNA damage repair function, etc., but it has not yet been translated into an effective weapon for reversing platinum resistance. Recently, autophagy has been proved to be closely related to platinum resistance, and the involved molecular mechanism may provide a new perspective on platinum resistance. The aim of this review is to sort out the studies related to autophagy and platinum resistance, and to focus on summarizing the relevant molecular mechanisms, so as to provide clues for future studies related to autophagy and platinum resistance.

Cell cycle associated miRNAs as target and therapeutics in lung cancer treatment

Lung cancer is the primary cause of cancer related deaths worldwide. Limited therapeutic options and resistance to existing drugs are the major hindrances to the clinical success of this cancer. In the past decade, several studies showed the role of microRNA (miRNA) driven cell cycle regulation in lung cancer progression. Therefore, these small nucleotide molecules could be utilized as promising tools in lung cancer therapy. In this review, we highlighted the recent advancements in lung cancer therapy using cell cycle linked miRNAs. By highlighting the roles of the specific cell cycle core regulators affiliated miRNAs in lung cancer, we further outlined how these miRNAs can be explored in early diagnosis and treatment strategies to prevent lung cancer. With the provided information from our review, more medical efforts can ensure a potential breakthrough in miRNA-based lung cancer therapy.

MicroRNAs as Predictors of Lung-Cancer Resistance and Sensitivity to Cisplatin

BACKGROUND

Platinum-based chemotherapy, cisplatin (DDP) specifically, is the main strategy for treating lung cancer (LC). However, currently, there is a lack of predictive drug-resistance markers, and there is increased interest in the development of a reliable and sensitive panels of markers for DDP chemotherapy-effectiveness prediction. MicroRNAs represent a perspective pool of markers for chemotherapy effectiveness.

OBJECTIVES

Data on miRNAs associated with LC DDP chemotherapy response are summarized and analyzed.

MATERIALS AND METHODS

A comprehensive review of the data in the literature and an analysis of bioinformatics resources were performed. The gene targets of miRNAs, as well as their reciprocal relationships with miRNAs, were studied using several databases.

RESULTS AND DISCUSSION

The complex analysis of bioinformatics resources and the literature indicated that the expressions of 12 miRNAs have a high predictive potential for LC DDP chemotherapy responses. The obtained information was discussed from the point of view of the main mechanisms of LC chemoresistance.

CONCLUSIONS

An overview of the published data and bioinformatics resources, with respect to the predictive microRNA markers of chemotherapy response, is presented in this review. The selected microRNAs and gene panel have a high potential for predicting LC DDP sensitiveness or DDP resistance as well as for the development of a DDP co-therapy.

Inhibition of miR-15a-5p Promotes the Chemoresistance to Pirarubicin in Hepatocellular Carcinoma via Targeting eIF4E

Chemoresistance has become a primary hurdle in the therapeutic outcome of hepatocellular carcinoma. Substantial evidences have demonstrated that microRNAs (miRNAs) are closely associated with the chemoresistance of hepatocellular carcinoma (HCC). Our investigation is aimed at testifying the influence of microRNA-15a-5p (miR-15a-5p)/eukaryotic translation initiation factor 4E (eIF4E) on hepatocellular carcinoma resistance to pirarubicin (THP). In our study, miR-15a-5p expression was increased in THP-treated HepG2 cells. Downregulation of miR-15a-5p blocked cell growth and elevated cell apoptosis of HepG2 cells treated with THP. Moreover, eIF4E was verified as a direct target of miR-15a-5p by binding its 3'-UTR, which was confirmed by luciferase report experiment. Additionally, eIF4E was negatively associated with the miR-15a-5p expression in HepG2 cells. Mechanically, eIF4E was proven as a specific downstream of miR-15a-5p and mediated the effects of miR-15a-5p on cell viability and apoptosis of HepG2 cells treated with THP. These findings supported that miR-15a-5p facilitated THP resistance of hepatocellular carcinoma cells by modulating eIF4E, thus providing an experimental basis that miR-15a-5p might act as a novel diagnostic target in hepatocellular carcinoma resistance to THP.

Circular RNA SLC26A4 regulates the maturation of microRNA-15a in non-small cell lung cancer cells

To the best of our knowledge, the oncogenic role of circular RNA solute carrier family 26 member 4 (circSLC26A4) has only been reported in cervical cancer, while its role in non-small cell lung cancer (NSCLC) is unknown. The present study explored the involvement of circSLC26A4 in NSCLC. NSCLC tissues and paired adjacent non-tumor tissues were collected from 64 patients with NSCLC. The expression levels of circSLC26A4, mature microRNA-15a (miR-15a) and miR-15a precursor in these tissues were determined by reverse transcription-quantitative PCR (RT-qPCR). NSCLC cells were transfected with pcDNA3.1-circSLC26A4 vector to overexpress circSLC26A4, followed by the measurement of the expression levels of mature miR-15a and miR-15a precursor using RT-qPCR. Cell proliferation was analyzed using a Cell Counting Kit-8 assay. circSLC26A4 expression was upregulated in NSCLC tissues, and its high expression was significantly associated with poor survival of patients with NSCLC. The expression levels of circSLC26A4 were correlated with the expression levels of mature miR-15a, but not the expression levels of miR-15a precursor in NSCLC tissues. In NSCLC cells, overexpression of circSLC26A4 was associated with downregulation of mature miR-15a expression, but not miR-15a precursor expression. A cell proliferation assay revealed that overexpression of circSLC26A4 reduced the inhibitory effects of overexpression of miR-15a on cell proliferation. Therefore, circSLC26A4 may suppress the maturation of miR-15a in NSCLC to inhibit cancer cell proliferation.

A Novel Androgen-Induced lncRNA FAM83H-AS1 Promotes Prostate Cancer Progression via the miR-15a/CCNE2 Axis

Prostate cancer (PCa) is one of the most common types of tumors among males worldwide. However, the roles of long noncoding RNAs (lncRNAs) in PCa remain unclear. This study shows that lncRNA FAM83H-AS1 is upregulated in prostate adenocarcinoma, bladder urothelial carcinoma, and kidney renal papillary cell carcinoma samples. Androgen receptor (AR) signaling plays the most important role in PCa tumorigenesis and development. In this study, the results validate that AR signaling is involved in upregulating FAM83H-AS1 expression in PCa cells. Loss-of-function assays demonstrate that FAM83H-AS1 acts as an oncogene in PCa by modulating cell proliferation, cell cycle, and migration. Bioinformatics analysis demonstrates that FAM83H-AS1 is remarkably related to the regulation of the cell cycle and DNA replication through affecting multiple regulators related to these pathways, such as CCNE2. Mechanically, we found that FAM83H-AS1 plays its roles through sponging miR-15a to promote CCNE2 expression. These findings indicate that FAM83H-AS1 is a novel diagnostic and therapeutic marker for PCa.

Lung cancer cells and their sensitivity/resistance to cisplatin chemotherapy: Role of microRNAs and upstream mediators

Cisplatin (CP) is a well-known chemotherapeutic agent with excellent clinical effects. The anti-tumor activity of CP has been demonstrated in different cancers such as breast, cervical, reproductive, lung, brain, and prostate cancers. However, resistance of cancer cells to CP chemotherapy has led to its failure in eradication of cancer cells, and subsequent death of patients with cancer. Fortunately, much effort has been put to identify molecular pathways and mechanisms involved in CP resistance/sensitivity. It seems that microRNAs (miRs) are promising candidates in mediating CP resistance/sensitivity, since they participate in different biological aspects of cells such as proliferation, migration, angiogenesis, and differentiation. In this review, we focus on miRs and their regulation in CP chemotherapy of lung cancer, as the most malignant tumor worldwide. Oncogenic miRs trigger CP resistance in lung cancer cells via targeting various pathways such as Wnt/β-catenin, Rab6, CASP2, PTEN, and Apaf-1. In contrast, onco-suppressor miRs inhibit oncogene pathways such as STAT3 to suppress CP resistance. These topics are discussed to determine the role of miRs in CP resistance/sensitivity. We also describe the upstream modulators of miRs such as lncRNAs, circRNAs, NF-κB, SOX2 and TRIM65 and their association with CP resistance/sensitivity in lung cancer cells. Finally, the effect of anti-tumor plant-derived natural compounds on miR expression during CP sensitivity of lung cancer cells is discussed.

Serum and Glucocorticoid-Inducible Kinase 1 (SGK1) in NSCLC Therapy

Non-small cell lung cancer (NSCLC) remains the most prevalent and one of the deadliest cancers worldwide. Despite recent success, there is still an urgent need for new therapeutic strategies. It is also becoming increasingly evident that combinatorial approaches are more effective than single modality treatments. This review proposes that the serum and glucocorticoid-inducible kinase 1 (SGK1) may represent an attractive target for therapy of NSCLC. Although ubiquitously expressed, SGK1 deletion in mice causes only mild defects of ion physiology. The frequent overexpression of SGK1 in tumors is likely stress-induced and provides a therapeutic window to spare normal tissues. SGK1 appears to promote oncogenic signaling aimed at preserving the survival and fitness of cancer cells. Most importantly, recent investigations have revealed the ability of SGK1 to skew immune-cell differentiation toward pro-tumorigenic phenotypes. Future studies are needed to fully evaluate the potential of SGK1 as a therapeutic target in combinatorial treatments of NSCLC. However, based on what is currently known, SGK1 inactivation can result in anti-oncogenic effects both on tumor cells and on the immune microenvironment. A first generation of small molecules to inactivate SGK1 has already been already produced.

Therapeutic effects of oligo-single-stranded DNA mimicking of hsa-miR-15a-5p on multiple myeloma

Despite the fact that a few novel agents improve the outcome of patients, MM remains incurable. Hence, developing a novel treatment strategy may prove to be promising for the clinical management of MM. Noncoding small RNAs, a cluster of RNAs that do not encode functional proteins, have been underlined that play a pivotal role in the pathogenesis of MM. Our previous study indicated that miR-15a acted as a tumor suppressor, which inhibited the cell proliferation and promoted the apoptosis of MM cells. The level of miR-15a was downregulated in MM cells and correlated with inferior outcome of MM patients. In the present study, we first developed an oligo-single-stranded DNA mimicking the sequence of hsa-miR-15a-5p (OMM-15a) and modified with locked nucleic acid (LNA-15a) to evaluate its anti-MM effects. Our results indicated that the LNA-15a presented an exciting anti-MM effect that showed notable cell growth suppression and apoptosis promotion in MM and other cancer cell lines through downregulating the expression level of target genes BCL-2, VEGF-A, and PHF19. Moreover, LNA-15a treatment significantly improved the anti-MM activity of bortezomib with the synergism effect in OCI-My5 MM cells. In our in vivo study, LNA-15a treatment significantly suppressed the tumor growth, and prolonged the survival of mice compared with the control group. However, our results indicated that the native form of oligo-single-stranded DNA mimic of hsa-miR-15a-5p (OMM-15a) without any modification had no effective inhibition on cell growth, even after increasing the dosage of OMM-15a in the treatment. Altogether, our finding provides the preclinical rationale to support the oligo-single-stranded DNA mimic of hsa-miR-15a with LNA modification, which is a promising tool for the therapy of both MM and other tumors with miR-15a downregulation.

Inhibition mechanism of lung cancer cell metastasis through targeted regulation of Smad3 by miR-15a

Effect of targeted regulation of mothers against decapentaplegic homolog 3 (Smad3) by microRNA-15a (miR-15a) on the proliferation, invasion and metastasis of non-small cell lung cancer (NSCLC) cells and its related mechanisms were investigated. Fifty pairs of NSCLC and para-cancerous tissues were collected to identify the expression level of miR-15a in NSCLC, para-cancerous tissue, and cell lines A549, H1299, H1975 and BEAS-2B by real-time fluorescence quantitative PCR (RT-PCR); A549 cells were transfected with miR-15a mimic; the MTT assay was performed to detect the role of miR-15a transfection in proliferation of A549 cells, the wound healing assay was carried out to identify the role of miR-15a in migration of A549 cells; Transwell invasion assay was conducted to analyze the role of miR-15a in invasion of A549 cells; western blotting was carried out to find the effect of miR-15a on Smad3 expression, and Spearman's rank correlation was used to analyze the correlation between miR-15a and Smad3 expression. NSCLC tissues and cells showed significantly lower miR-15a expression, compared with para-cancerous tissues and normal cell lines (P=0.023). miR-15a was significantly more expressed in A549 cells transfected with miR-15a mimic (P=0.043). Overexpression of miR-15a can significantly inhibit A549 cell proliferation (P=0.038), migration (P=0.033) and invasion (P=0.025), and significantly reduced the expression level of Smad3 (P=0.031) in A549 cells. Spearman's rank correlation showed negative correlation of miR-15a expression with Smad3, which may indicate negative regulation (r=−0.34, P<0.0001). Inhibition of proliferation, migration and invasion of NSCLC cells can be achieved with targeted regulation of Smad3 by miR-15a.

HOXA11-AS regulates JAK-STAT pathway by miR-15a-3p/STAT3 axis to promote the growth and metastasis in liver cancer

BACKGROUND

HOMEOBOX A11 (HOXA11) antisense RNA (HOXA11-AS), a newly identified long noncoding RNAs, is involved in the carcinogenic process of several human tumors. However, the role of HOXA11-AS in liver cancer progression is not well understood.

MATERIALS AND METHODS

This study used liver cancer tissues and cell lines (CSQT-2 and HCCLM3) to explore the potential mechanism of HOXA11-AS. Quantitative real-time polymerase chain reaction and Western blot were applied to evaluate the bio-molecules expression. Bioinformatics analysis, RNA pull down and luciferase report assay were applied to determine the molecules bind. MTT, transwell, and wound healing assay were used to measure the cell growth situation.

RESULTS

HOXA11-AS was highly expressed in liver cancer tissues and cell lines, which was closely related with poor prognosis in patients with liver cancer. HOXA11-AS could act as a competing endogenous RNA for miR-15a-3p. Besides, miR-15a-3p negatively controlled its target molecule signal transducer and activator of transcription 3 (STAT3). Furthermore, a linear regression analysis and biological experiments showed a positive correlation between HOAX11-AS and STAT3. Moreover, HOAX11-AS overexpression activated the Janus kinase (JAK)-STAT pathway and thus promoted the growth, migration, and invasion of liver cancer cells, which might be through regulating miR-15a-3p/STAT3 axis.

CONCLUSION

Our study suggested that HOAX11-AS could regulate the JAK-STAT signaling pathway by miR-15a-3p/STAT3 axis to promote the progression of liver cancer. Thus, HOXA11-AS may be regarded as an effective biomarker with diagnostic, prognostic, and therapeutic potentials for liver cancer.

Long non-coding RNA UCA1 exerts growth modulation by miR-15a in human thyroid cancer TPC-1 cells

Thyroid cancer is widely diagnosed as malignancy in endocrine system. This study attempted to validate UCA1 possessed modulatory function on cell proliferation and epithelial mesenchymal transition (EMT) in human thyroid cancer cell line TPC-1. Ectopic expression of UCA1 was induced in TPC-1 cells by transfection. CCK-8 assays were employed to value cell viability. Cell apoptosis analysis was conducted through flow cytometry. We found that overexpressed UCA1 strongly promoted cell proliferation. However, the knockdown of UCA1 suppressed cell proliferation and induced obvious cell apoptosis. Besides, cell EMT was promoted by overexpressed UCA1 and was inhibited by the knockdown of UCA1. Further study revealed that miR-15a level in TPC-1 cells was suppressed by overexpressed UCA1. Simultaneous overexpression of UCA1 and miR-15a partly alleviated UCA1-induced growth, identifying that miR-15a was a possible target of UCA1. At last, the Hippo and JNK signal pathways were activated by overexpressed UCA1 but were then weakened by the adding of miR-15a. In conclusion, our study revealed UCA1/miR-15a axis implicated in thyroid cancer cells EMT, exposing a novel mechanism of thyroid cancer progression.

miR-15a-3p Suppresses Prostate Cancer Cell Proliferation and Invasion by Targeting SLC39A7 Via Downregulating Wnt/β-Catenin Signaling Pathway

Background: MiR-15a-3p has been reported as a tumor suppressor in several kinds of cancer, including cervical cancer and gastric cancer. However, the precise molecular mechanisms underlying its role in prostate cancer (PCa) remain largely unknown. Methods: The expression of miR-15a-3p was determined in PCa tissues and cell lines using quantitative real time PCR. The biological function of miR-15a-3p in PCa cells was investigated using a MTT assay, Edu staining and transwell assay. Moreover, luciferase reporter assay, quantitative real time PCR and western blotting were used to identify and verify the direct downstream target of miR-15a-3p. Results: We found that the expression of miR-15a-3p was down-regulated in both PCa tissues and cell lines. The in vitro results showed that miR-15a-3p overexpression suppressed cell proliferation, invasion, and epithelial-mesenchymal transition (EMT) via down-regulating Wnt/β-catenin signaling in PCa cells. Moreover, SLC39A7 was a direct downstream target of miR-15a-3p. Furthermore, SLC39A7 overexpression attenuated the effects of miR-15a-3p on cell proliferation, invasion, Wnt/β-catenin pathway and EMT molecules. Conclusions: In summary, our study indicated that miR-15a-3p inhibited the proliferation, invasion, and EMT process of PCa cells via targeting SLC39A7 and suppressing Wnt/β-catenin signaling pathway, which may represent a new therapeutic objective for PCa treatment.

Prediction of microRNA-disease associations based on distance correlation set

BACKGROUND

Recently, numerous laboratory studies have indicated that many microRNAs (miRNAs) are involved in and associated with human diseases and can serve as potential biomarkers and drug targets. Therefore, developing effective computational models for the prediction of novel associations between diseases and miRNAs could be beneficial for achieving an understanding of disease mechanisms at the miRNA level and the interactions between diseases and miRNAs at the disease level. Thus far, only a few miRNA-disease association pairs are known, and models analyzing miRNA-disease associations based on lncRNA are limited.

RESULTS

In this study, a new computational method based on a distance correlation set is developed to predict miRNA-disease associations (DCSMDA) by integrating known lncRNA-disease associations, known miRNA-lncRNA associations, disease semantic similarity, and various lncRNA and disease similarity measures. The novelty of DCSMDA is due to the construction of a miRNA-lncRNA-disease network, which reveals that DCSMDA can be applied to predict potential lncRNA-disease associations without requiring any known miRNA-disease associations. Although the implementation of DCSMDA does not require known disease-miRNA associations, the area under curve is 0.8155 in the leave-one-out cross validation. Furthermore, DCSMDA was implemented in case studies of prostatic neoplasms, lung neoplasms and leukaemia, and of the top 10 predicted associations, 10, 9 and 9 associations, respectively, were separately verified in other independent studies and biological experimental studies. In addition, 10 of the 10 (100%) associations predicted by DCSMDA were supported by recent bioinformatical studies.

CONCLUSIONS

According to the simulation results, DCSMDA can be a great addition to the biomedical research field.

MicroRNA-106b-5p regulates cisplatin chemosensitivity by targeting polycystic kidney disease-2 in non-small-cell lung cancer

Systemic therapy with cytotoxic agents remains one of the main treatment methods for non-small-cell lung cancer (NSCLC). Cisplatin is a commonly used chemotherapeutic agent, that, when combined with other drugs, is an effective treatment for NSCLC. However, effective cancer therapy is hindered by a patient's resistance to cisplatin. Unfortunately, the potential mechanism underlying such resistance remains unclear. In this study, we explored the mechanism of microRNA-106b-5p (miR-106b-5p), which is involved in the resistance to cisplatin in the A549 cell line of NSCLC. Quantitative real-time PCR was used to test the expression of miR-106-5p in the A549 and the A549/DDP cell line of NSCLC. The cell counting kit-8 assay was used to detect cell viability. Flow cytometry was used to measure cell cycle and cell apoptosis. Luciferase reporter assays and western blot were performed to confirm whether polycystic kidney disease-2 (PKD2) is a direct target gene of miR-106b-5p. Immunohistochemistry was performed to examine the distribution of PKD2 expression in patients who are sensitive and resistant to cisplatin. The experiments indicated that the expression of miR-106b-5p was significantly decreased in A549/DDP compared with that in A549. MiR-106b-5p affected the tolerance of cells to cisplatin by negatively regulating PKD2. Upregulation of miR-106b-5p or downregulation of PKD2 expression can cause A549/DDP cells to become considerably more sensitive to cisplatin. The results showed that miR-106b-5p enhanced the sensitivity of A549/DDP cells to cisplatin by targeting the expression of PKD2. These findings suggest that the use of miR-106b-5p may be a promising clinical strategy in the treatment of NSCLC.

Identification of novel diagnostic and prognostic miRNA signatures in endometrial cancer

With the goal of identifying diagnostic and prognostic biomarkers in endometrial cancer, miRNA-profiling was carried out with formalin-fixed paraffin embedded (FFPE) tissue samples from 49 endometrial cancer patients. Results using an 84-cancer specific miRNA panel identified the upregulation of miR-141-3p and miR-96-5p along with a downregulation of miR-26, miR-126-3p, miR-23b, miR-195-5p, miR-374a and let-7 family of miRNAs in endometrial cancer. We validated the dysregulated expression of the identified miRNAs in a panel of endometrial cancer cell-lines. Immunohistochemical analysis of the tissue micro array derived from these patients established the functional correlation between the decreased expression of tumor suppressive miRNAs and their target oncogenes: ERBB2, EGFR, EPHA2, BAX, GNA12, GNA13, and JUN. Comparative analysis of the samples from the patients with extended progression-free survival (PFS) ( > 21 months) versus the patients with the PFS of < 21 months indicated increased expression of tumor suppressive miR-142-3p, miR-142-5p, and miR-15a-5p in samples from extended PFS patients. In addition to defining a specific set of miRNAs and their target genes as potential diagnostic biomarkers, our studies have identified tumor suppressive miR-142 cluster and miR-15a as predictors of favorable prognosis for therapy response in endometrial cancer.

MicroRNA-15a inhibition protects against hypoxia/reoxygenation-induced apoptosis of cardiomyocytes by targeting mothers against decapentaplegic homolog 7

Myocardial ischemia/reperfusion (I/R) injury is a major pathological process in coronary heart disease and cardiac surgery, and is associated with aberrant microRNA (miR) expression. Previous studies have demonstrated that inhibition of miR-15a expression may ameliorate I/R-induced myocardial injury. In the present study, the potential role and underlying mechanism of miR-15a in hypoxia/reoxygenation-induced apoptosis of cardiomyocytes was investigated. Myocardial I/R was simulated in cultured H9c2 cells by 24 h hypoxia followed by 24 h reoxygenation. Using recombinant lentivirus vectors, the inhibition of miR-15a was indicated to significantly reduce cardiomyocyte apoptosis and release of lactate dehydrogenase and malondialdehyde. Conversely, upregulated miR-15a expression was pro-apoptotic. Mothers against decapentaplegic homolog 7 (SMAD7) was identified by bioinformatics analysis as a potential target of miR-15a. Luciferase reporter assays and western blotting for endogenous SMAD7 protein indicated that miR-15a inhibited SMAD7 expression via its 3′-untranslated region. Nuclear levels of nuclear factor-κB (NF-κB) p65 were increased by miR-15a expression and decreased by miR-15a inhibition, which is consistent with the possibility that the inhibition of SMAD7 by miR-15a results in NF-κB activation. These findings suggested that the therapeutic effects of miR-15a inhibition on I/R injury may potentially be explained by its ability to release SMAD-7-dependent NF-κB inhibition. This may provide evidence for miR-15a as a potential therapeutic target for the treatment of cardiac I/R injury.

Interactions between anticancer active platinum complexes and non-coding RNAs/microRNAs

Platinum(II) complexes such as cisplatin, carboplatin and oxaliplatin are clinically approved for the therapy of various solid tumors. Challenging pathogenic properties of cancer cells and the response of cancers towards platinum-based drugs are strongly influenced by non-coding small RNA molecules, the microRNAs (miRNAs). Both increased platinum activity and formation of tumor resistance towards platinum drugs are controlled by miRNAs. This review gives an overview of the interactions between platinum-based drugs and miRNAs, and their influence on platinum activity in various cancer types is discussed.

Autophagy is not uniformly cytoprotective: a personalized medicine approach for autophagy inhibition as a therapeutic strategy in non-small cell lung cancer

BACKGROUND

Lung cancer is the leading cause of cancer-related death worldwide. In addition to surgical resection, which is considered first-line treatment at early stages of the disease, chemotherapy and radiation are widely used when the disease is advanced. Of multiple responses that may occur in the tumor cells in response to cancer therapy, the functional importance of autophagy remains equivocal; this is likely to restrict current efforts to sensitize this malignancy to chemotherapy and/or radiation by pharmacological interference with the autophagic response.

SCOPE OF REVIEW

In this review, we attempt to summarize the current state of knowledge based on studies that evaluated the function of autophagy in non-small cell lung cancer (NSCLC) cells in response to radiation and the most commonly used chemotherapeutic agents.

MAJOR CONCLUSIONS

In addition to the expected prosurvival function of autophagy, where autophagy inhibition enhances the response to therapy, autophagy appears also to have a "non-cytoprotective" function, where autophagy blockade does not affect cell viability, clonogenicity or tumor volume in response to therapy. In other cases, autophagy may actually mediate drug action via expression of its cytotoxic function.

GENERAL SIGNIFICANCE

These observations emphasize the complexity of autophagy function when examined in different tumor cell lines and in response to different chemotherapeutic agents. A more in-depth understanding of the conditions that promote the unique functions of autophagy is required in order to translate preclinical findings of autophagy inhibition to the clinic for the purpose of improving patient response to chemotherapy and radiation.

MicroRNA-15a Inhibits Proliferation and Induces Apoptosis in CNE1 Nasopharyngeal Carcinoma Cells

Nasopharyngeal carcinoma (NPC) is a highly metastatic cancer, frequently occurring in Southeast Asia and Southern China. Several microRNAs (miRNAs) have been shown to have an inhibitive effect on NPC, while the effect of miR-15a on NPC remains unclear. Thus, our study aimed to investigate the potential effect of miR-15a on NPC cell proliferation, apoptosis, and possible functional mechanism. Human NPC CNE1 cells were transfected with miR-15a mimics, miR-15a inhibitors, or a control. Afterward, cell viability and apoptosis were assayed by using CCK-8, BrdU assay, and flow cytometry. Moreover, Western blot was used to detect the expression changes of proliferation and apoptosis of related proteins. As a result, miR-15a overexpression significantly reduced cell proliferation (p < 0.01 or p < 0.001) and induced cell apoptosis (p < 0.001), while miR-15a suppression got the opposite result for cell proliferation and apoptosis. In addition, miR-15a overexpression upregulated the protein levels of p27, GSK-3β, Bax, procaspase 3, and active caspase 3, whereas miR-15a suppression downregulated these proteins. The protein level of p21 was not significantly regulated by miR-15a overexpression or suppression. These results indicated that miR-15a played a role for inhibition of proliferation and induction of apoptosis in CNE1 cells.