Regulating miRNA by natural agents as a new strategy for cancer treatment

microRNA-137 functions as a tumor suppressor in human non-small cell lung cancer by targeting SLC22A18

Our previous study demonstrated that the overexpression of solute carrier family 22 member 18 (SLC22A18) in human non-small cell lung cancer (NSCLC) tissues might be associated with tumor progression and patients' prognosis. The aim of this study was to investigate the molecular mechanisms underlying its roles in NSCLC. As a result, bioinformatics analysis and luciferase reporter assay showed that microRNA (miRNA)-137 directly targeted SLC22A18 in NSCLC cells. Then, functional studies indicated that the ectopic expression of miR-137 significantly inhibited NSCLC cell proliferation, invasion and migration by targeting SLC22A18. More importantly, the decreased expression of miR-137 in clinical NSCLC tissues was correlated with advanced TNM stage, positive metastasis and poor prognosis of patients with this malignancy. In conclusion, these findings offer the convincing evidence that the roles of SLC22A18 in NSCLC progression may be partially caused by the regulatory effects of miR-137, which may function as a tumor suppressor. Our clinical data further indicated that miR-137 may be an independent favorable prognostic factor in NSCLC patients.

Curcumin inhibits cell growth and invasion through up-regulation of miR-7 in pancreatic cancer cells

Accumulating evidence has revealed that a natural compound curcumin exerts its anti-tumor activity in pancreatic cancer. However, the underlying molecular mechanism remains elusive. Recently, miRNAs have been demonstrated to play a crucial role in tumorigenesis, suggesting that targeting miRNAs could be a promising approach for the treatment of human cancers. In this study, we explored whether curcumin regulates miR-7, leading to the inhibition of cell growth, migration and invasion in pancreatic cancer cells. We observed that curcumin suppressed cell growth, migration and invasion, and induced cell apoptosis, which is associated with increased expression of miR-7 and subsequently decreased expression of SET8, one of the miR-7 targets. These findings demonstrated that targeting miR-7 by curcumin could be a novel strategy for the treatment of pancreatic cancer.

Ficus carica latex prevents invasion through induction of let-7d expression in GBM cell lines

Glioblastoma multiforme (GBM) is one of the deadliest human malignancies. A cure for GBM remains elusive, and the overall survival time is less than 1 year. Thus, the development of more efficient therapeutic approaches for the treatment of these patients is required. Induction of tumor cell death by certain phytochemicals derived from medicinal herbs and dietary plants has become a new frontier for cancer therapy research. Although the cancer suppressive effect of Ficus carica (fig) latex (FCL) has been determined in a few cancer types, the effect of this latex on GBM tumors has not been investigated. Therefore, in the current study, the anti-proliferative activity of FCL and the effect of the FCL-temozolomide (TMZ) combination were tested in the T98G, U-138 MG, and U-87 MG GBM cell lines using the WST-1 assay. The mechanism of cell death was analyzed using Annexin-V/FITC and TUNEL assays, and the effect of FCL on invasion was tested using the chick chorioallantoic membrane assay. To determine the effect of FCL on GBM progression, the expression levels of 40 GBM associated miRNAs were analyzed in T98G cells using RT-qPCR. According to the obtained data, FCL causes cell death in GBM cells with different responses to TMZ, and this effect is synergistically increased in combination with TMZ. In addition, the current study is the first to demonstrate the effect of FCL on modulation of let-7d expression, which may be an important underlying mechanism of the anti-invasive effect of this extract.

A novel small-molecule compound diaporine A inhibits non-small cell lung cancer growth by regulating miR-99a/mTOR signaling

MicroRNAs (miRNAs) dysregulation is critically involved in lung cancer. Regulating miRNAs by natural agents may be a new strategy for cancer treatment. We previously found that a novel small-molecule compound diaporine A (D261), a natural product of endophytic fungus 3lp-10, had potential anti-cancer activites. In the present study, the inhibitory effect of D261 on non-small cell lung cancer (NSCLC) growth and its possible mechanisms involving miRNA regulation were investigated. By cell viability assay, cell proliferation analysis, and clonal growth assay, we proved that D261 effectively inhibited the proliferation of NSCLC cells (NCI-H460 and A549) in vitro. Administration of D261 (5 mg/kg) to NCI-H460 xenografts bearing mice also inhibited tumor growth and decreased the expression of cell proliferation regulator, midkine. Moreover, D261 induced cell cycle arrest with a reduced expression of various G 1/S transition-related molecules including cyclin D1, cyclin E1, CDK4, and CDK2, but without influencing apoptosis in NSCLC cells. Intriguingly, D261 modified expressions of some miRNAs and especially upregulated miR-99a, whose direct target was mammalian target of rapamycin (mTOR). Furthermore, overexpression of miR-99a antagonized the anti-tumor actions of D261 including the suppression of mTOR pathway activation, cell cycle-related proteins and cell growth. In addition, blocking of miR-99a expression by transfection of miR-99a inhibitors before D261 treatment counteracted the anti-tumor effects of D261. These data suggest that miR-99a/mTOR pathway was involved in D261-induced tumor suppression in NSCLC cells. D261 might be a potent anti-cancer agent by upregulating miR-99a expression.

MicroRNAs in personalized cancer therapy

MicroRNAs (miRNAs) are small endogenous noncoding single-stranded RNAs. They critically regulate the post-transcriptional activity of several key physiological and pathological cell processes including cancer. Through their transcriptional regulatory functions, miRNAs control tumor proliferation, invasion and metastasis. The expression of miRNAs is altered in malignancies. It could be either upregulated or downregulated depending upon the role of a particular miRNA in the pathogenetic development of the tumor. The upregulated miRNAs exert an 'oncogenic' effect leading to tumor proliferation and metastasis. The downregulated miRNAs have 'tumor suppressor' effects. Recent studies have demonstrated that miRNAs have a role in the early diagnosis, prognosis and treatment outcome assessment of cancers. Every tumor has specific miRNA alterations, i.e. some are overexpressed and others are downregulated. These altered miRNAs can be used as a tumor-specific 'signature' for potential clinical use in improving the accuracy of diagnosis, determining prognosis and as therapeutic targets for therapy. Specific miRNAs can be targeted using oligonucleotide sequences corresponding to the altered miRNAs. These are referred to as 'antagomirs'. Depending upon the miRNA alterations in the tumor of an individual patient, one could design targeted therapies for personalized medicine in patients. Hence, miRNAs have an immense role in personalized cancer therapy.

Intravital biobank and personalized cancer therapy: the correlation with omics

Biobanks have played a decisive role in all aspects of the field of cancer, including pathogenesis, diagnosis, prognosis and treatment. The significance of cancer biobanks is epitomized through the appropriate application of various "-omic" techniques (omics). The mutually motivated relationship between biobanks and omics has intensified the development of cancer research. Human cancer tissues that are maintained in intravital biobanks (or living tissue banks) retain native tumor microenvironment, tissue architecture, hormone responsiveness and cell-to-cell signalling properties. Intravital biobanks replicate the structural complexity and heterogeneity of human cancers, making them an ideal platform for preclinical studies. The application of omics with intravital biobanks renders them more active, which makes it possible for the cancer-related evaluations to be dynamically monitored on a real-time basis. Integrating intravital biobank and modern omics will provide a useful tool for the discovery and development of new drugs or novel therapeutic strategies. More importantly, intravital biobanks may play an essential role in the creation of meaningful patient-tailored therapies as for personalized medicine.