RETRACTED: Increased Ras GTPase activity is regulated by miRNAs that can be attenuated by CDF treatment in pancreatic cancer cells

Indoloquinoline-Mediated Targeted Downregulation of KRAS through Selective Stabilization of the Mid-Promoter G-Quadruplex Structure

KRAS is a well-validated anti-cancer therapeutic target, whose transcriptional downregulation has been demonstrated to be lethal to tumor cells with aberrant KRAS signaling. G-quadruplexes (G4s) are non-canonical nucleic acid structures that mediate central dogmatic events, such as DNA repair, telomere elongation, transcription and splicing events. G4s are attractive drug targets, as they are more globular than B-DNA, enabling more selective gene interactions. Moreover, their genomic prevalence is increased in oncogenic promoters, their formation is increased in human cancers, and they can be modulated with small molecules or targeted nucleic acids. The putative formation of multiple G4s has been described in the literature, but compounds with selectivity among these structures have not yet been able to distinguish between the biological contribution of the predominant structures. Using cell free screening techniques, synthesis of novel indoloquinoline compounds and cellular models of KRAS-dependent cancer cells, we describe compounds that choose between KRAS promoter G4_near and G4_mid, correlate compound cytotoxic activity with KRAS regulation, and highlight G4_mid as the lead molecular non-canonical structure for further targeting efforts.

Targeting KRAS Regulation with PolyPurine Reverse Hoogsteen Oligonucleotides

KRAS is a GTPase involved in the proliferation signaling of several growth factors. The KRAS gene is GC-rich, containing regions with known and putative G-quadruplex (G4) forming regions. Within the middle of the G-rich proximal promoter, stabilization of the physiologically active G4_mid structure downregulates transcription of KRAS; the function and formation of other G4s within the gene are unknown. Herein we identify three putative G4-forming sequences (G4FS) within the KRAS gene, explore their G4 formation, and develop oligonucleotides targeting these three regions and the G4_mid forming sequence. We tested Polypurine Reverse Hoogsteen hairpins (PPRHs) for their effects on KRAS regulation via enhancing G4 formation or displacing G-rich DNA strands, downregulating KRAS transcription and mediating an anti-proliferative effect. Five PPRH were designed, two against the KRAS promoter G4_mid and three others against putative G4FS in the distal promoter, intron 1 and exon 5. PPRH binding was confirmed by gel electrophoresis. The effect on KRAS transcription was examined by luciferase, FRET Melt², qRT-PCR. Cytotoxicity was evaluated in pancreatic and ovarian cancer cells. PPRHs decreased activity of a luciferase construct driven by the KRAS promoter. PPRH selectively suppressed proliferation in KRAS dependent cancer cells. PPRH demonstrated synergistic activity with a KRAS promoter selective G4-stabilizing compound, NSC 317605, in KRAS-dependent pancreatic cells. PPRHs selectively stabilize G4 formation within the KRAS mid promoter region and represent an innovative approach to both G4-stabilization and to KRAS modulation with potential for development into novel therapeutics.

Nano Metal based Herbal theranostics for Cancer management: coalescing nature's boon with nanotechnological advancement

Cancer is amongst the leading public health problems globally with continuously increasing prevalence rate that demands for extensive and expensive treatment. Despite availability of number of potential cancer therapies, inadequate success has been achieved due to complexity and heterogeneity of tumors. Moreover, late/ terminal stage cancer leads to multidrug resistance, excruciating side effects, recurrence, etc. This is because of low penetrability and deleterious effects of drug on non-target cells/ tissues. This requires for cost effective, efficacious, alternative/ adjunct, complementary medicines with targeted drug delivery approach. A potential strategy to resolve this difficulty is to use theranostics i.e., formulations having both a therapeutic element and an imaging agent. Phytotherapeutics have been extensively used since times immemorial, having wide acceptability, easy availability, minimal side effects and comparatively inexpensive. These herbal formulations are mostly orally administered and thus subjected to adverse pH, enzymatic degradation, poor gut absorption, low bioavailability and non-targeted delivery that ultimately lead to their poor effectiveness. Constraints associated with conventional phyto-pharmaceuticals can be improved by designing and using "Nano Delivery Systems" (NDS). The foremost aim of metal based NDS is to provide sustained drug release, site-specific action, improved patient's compliance and enhanced efficacy. Metal Nanocarriers carrying herbal drugs will avoid these obstructions, so the drug can circulate into the blood for a longer period of time and provide optimal amount of the drug to the site of action. Besides, Herbal drugs with NDS thus would be efficacious as alternative/ complementary cancer theranostics. Present review describes about novel theranostic systems employing metal nanocarriers with diagnostic and therapeutic properties as are an effective strategy for cancer treatment. These systems when conjugated with herbal drugs provide an efficient management strategy for cancer.

Gold/alpha-lactalbumin nanoprobes for the imaging and treatment of breast cancer

Theranostic agents should ideally be renally cleared and biodegradable. Here, we report the synthesis, characterization and theranostic applications of fluorescent ultrasmall gold quantum clusters that are stabilized by the milk metalloprotein alpha-lactalbumin. We synthesized three types of these nanoprobes that together display fluorescence across the visible and near-infrared spectra when excited at a single wavelength through optical colour coding. In live tumour-bearing mice, the near-infrared nanoprobe generates contrast for fluorescence, X-ray computed tomography and magnetic resonance imaging, and exhibits long circulation times, low accumulation in the reticuloendothelial system, sustained tumour retention, insignificant toxicity and renal clearance. An intravenously administrated near-infrared nanoprobe with a large Stokes shift facilitated the detection and image-guided resection of breast tumours in vivo using a smartphone with modified optics. Moreover, the partially unfolded structure of alpha-lactalbumin in the nanoprobe helps with the formation of an anti-cancer lipoprotein complex with oleic acid that triggers the inhibition of the MAPK and PI3K-AKT pathways, immunogenic cell death and the recruitment of infiltrating macrophages. The biodegradability and safety profile of the nanoprobes make them suitable for the systemic detection and localized treatment of cancer.

Curcumin: From a controversial "panacea" to effective antineoplastic products

BACKGROUND

Curcumin, a controversial "panacea," has been broadly studied. Its bioactivities including antioxidant, anti-inflammatory, and especially antineoplastic activities have been documented. However, due to its extensive bioactivities, some scientists hold a skeptical point of view toward curcumin and described curcumin as a "deceiver" to chemists. The objective of this study was to explore curcumin's another possibility as a potential supplementary leading compound to cancer treatments.

METHODS

Literature searches were conducted using electronic databases. Search terms such as "curcumin," "curcumin analogues," and so on were used. The literatures were collected and summarized. In this article, reported targets of curcumin are reviewed. The limitations of a curcumin as a therapeutic anticancer product including low bioavailability and poor targeting are mentioned. Furthermore, modified curcumin analogues and antitumor mechanisms are listed and discussed in the aspects of cell death and tumor microenvironment including angiogenesis, tissue hypoxia status, and energy metabolism.

RESULTS

Several possible modification strategies were presented by analyzing the relationships between the antitumor activity of curcumin analogues and their structural characteristics, including the introduction of hydrophilic group, shortening of redundant hydrocarbon chain, the introduction of extra chemical group, and so on.

CONCLUSIONS

From our perspective, after structural modification curcumin could be more effective complementary product for cancer therapies by the enhancement of targeting abilities and the improvement of bioavailability.

Clinical Implication of MicroRNAs in Molecular Pathology: An Update for 2018

MicroRNAs (miRNAs) are poised to provide diagnostic, prognostic, and therapeutic targets for several diseases including malignancies for precision medicine applications. The miRNAs have immense potential in the clinical arena because they can be detected in the blood, serum, tissues (fresh and formalin-fixed paraffin-embedded), and fine-needle aspirate specimens. The most attractive feature of miRNA-based therapy is that a single miRNA could be useful for targeting multiple genes that are deregulated in cancers, which can be further investigated through systems biology and network analysis that may provide cancer-specific personalized therapy.

Chemopreventive and therapeutic potential of curcumin in esophageal cancer: Current and future status

Esophageal cancer is a common malignant tumor with an increasing trend during the past three decades. Currently, esophagectomy, often in combination with neoadjuvant chemo- and radiotherapy, is the cornerstone of curative treatment for esophageal cancer. However, esophagostomy is related to significant risks of perioperative mortality and morbidity, as well as lengthy recovery. Moreover, the adjuvant therapies including chemotherapy and radiotherapy are associated with numerous side effects, limiting compliance and outcome. The dietary agent curcumin has been extensively studied over the past few decades and is known to have many biological activities especially in regard to the prevention and potential treatment of cancer. This review summarizes the chemo-preventive and chemotherapeutic potential of curcumin in esophageal cancer in both preclinical and clinical settings.

Recent progress on the effects of microRNAs and natural products on tumor epithelial-mesenchymal transition

Epithelial–mesenchymal transition (EMT) is a biological process of phenotypic transition of epithelial cells that can promote physiological development as well as tissue healing and repair. In recent years, cancer researchers have noted that EMT is closely related to the occurrence and development of tumors. When tumor cells undergo EMT, they can develop enhanced migration and local tissue invasion abilities, which can lead to metastatic growth. Nevertheless, two researches in NATURE deny its necessity in specific tumors and that is discussed in this review. The degree of EMT and the detection of EMT-associated marker molecules can also be used to judge the risk of metastasis and to evaluate patients’ prognosis. MicroRNAs (miRNAs) are noncoding small RNAs, which can inhibit gene expression and protein translation through specific binding with the 3′ untranslated region of mRNA. In this review, we summarize the miRNAs that are reported to influence EMT through transcription factors such as ZEB, SNAIL, and TWIST, as well as some natural products that regulate EMT in tumors. Moreover, mutual inhibition occurs between some transcription factors and miRNAs, and these effects appear to occur in a complex regulatory network. Thus, understanding the role of miRNAs in EMT and tumor growth may lead to new treatments for malignancies. Natural products can also be combined with conventional chemotherapy to enhance curative effects.

Curcumin induces G2/M arrest, apoptosis, NF-κB inhibition, and expression of differentiation genes in thyroid carcinoma cells

PURPOSE

The therapy of unresectable advanced thyroid carcinomas shows unfavorable outcome. Constitutive nuclear factor-κB (NF-κB) activation in thyroid carcinomas frequently contributes to therapeutic resistance; the radioiodine therapy often fails due to the loss of differentiated functions in advanced thyroid carcinomas. Curcumin is known for its anticancer properties in a series of cancers, but only few studies have focused on thyroid cancer. Our aim was to evaluate curcumin's molecular mechanisms and to estimate if curcumin could be a new therapeutic option in advanced thyroid cancer.

METHODS

Human thyroid cancer cell lines TPC-1 (papillary), FTC-133 (follicular), and BHT-101 (anaplastic) were treated with curcumin. Using real-time PCR analysis, we investigated microRNA (miRNA) and mRNA expression levels. Cell cycle, Annexin V/PI staining, and caspase-3 activity analysis were performed to detect apoptosis. NF-κB p65 activity and cell proliferation were analyzed using appropriate ELISA-based colorimetric assay kits.

RESULTS

Treatment with 50 μM curcumin significantly increased the mRNA expression of the differentiation genes thyroglobulin (TG) and sodium iodide symporter (NIS) in all three cell lines and induced inhibition of cell proliferation, apoptosis, and decrease of NF-κB p65 activity. The miRNA expression analyses showed a significant deregulation of miRNA-200c, -21, -let7c, -26a, and -125b, known to regulate cell differentiation and tumor progression. Curcumin arrested cell growth at the G2/M phase.

CONCLUSIONS

Curcumin increases the expression of redifferentiation markers and induces G2/M arrest, apoptosis, and downregulation of NF-κB activity in thyroid carcinoma cells. Thus, curcumin appears to be a promising agent to overcome resistance to the conventional cancer therapy.

Targeting miRNAs by polyphenols: Novel therapeutic strategy for cancer

In the recent years, polyphenols have gained significant attention in scientific community owing to their potential anticancer effects against a wide range of human malignancies. Epidemiological, clinical and preclinical studies have supported that daily intake of polyphenol-rich dietary fruits have a strong co-relationship in the prevention of different types of cancer. In addition to direct antioxidant mechanisms, they also regulate several therapeutically important oncogenic signaling and transcription factors. However, after the discovery of microRNA (miRNA), numerous studies have identified that polyphenols, including epigallocatechin-3-gallate, genistein, resveratrol and curcumin exert their anticancer effects by regulating different miRNAs which are implicated in all the stages of cancer. MiRNAs are short, non-coding endogenous RNA, which silence the gene functions by targeting messenger RNA (mRNA) through degradation or translation repression. However, cancer associated miRNAs has emerged only in recent years to support its applications in cancer therapy. Preclinical experiments have suggested that deregulation of single miRNA is sufficient for neoplastic transformation of cells. Indeed, the widespread deregulation of several miRNA profiles of tumor and healthy tissue samples revealed the involvement of many types of miRNA in the development of numerous cancers. Hence, targeting the miRNAs using polyphenols will be a novel and promising strategy in anticancer chemotherapy. Herein, we have critically reviewed the potential applications of polyphenols on various human miRNAs, especially which are involved in oncogenic and tumor suppressor pathways.

KRAS-related noncoding RNAs in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease with a poor overall prognosis. However, curative resection during the early stages of the disease can greatly improve survival rates, highlighting the importance of early screening and detection. Studies of noncoding RNAs, primarily microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), provide important insights into strategies for the early detection of KRAS-driven PDAC. Here, we summarize our studies and review current reports on research investigating KRAS-related miRNAs and lncRNAs, emphasizing their aberrant expression, mechanisms, carcinogenic effects, and prognostic and predictive capacities in PDAC.

Current state of phenolic and terpenoidal dietary factors and natural products as non-coding RNA/microRNA modulators for improved cancer therapy and prevention

The epigenetic regulation of cancer cells by small non-coding RNA molecules, the microRNAs (miRNAs), has raised particular interest in the field of oncology. These miRNAs play crucial roles concerning pathogenic properties of cancer cells and the sensitivity of cancer cells towards anticancer drugs. Certain miRNAs are responsible for an enhanced activity of drugs, while others lead to the formation of tumor resistance. In addition, miRNAs regulate survival and proliferation of cancer cells, in particular of cancer stem-like cells (CSCs), that are especially drug-resistant and, thus, cause tumor relapse in many cases. Various small molecule compounds were discovered that target miRNAs that are known to modulate tumor aggressiveness and drug resistance. This review comprises the effects of naturally occurring small molecules (phenolic compounds and terpenoids) on miRNAs involved in cancer diseases.

Cancer Stem Cells: The Potential Targets of Chinese Medicines and Their Active Compounds

The pivotal role of cancer stem cells (CSCs) in the initiation and progression of malignancies has been rigorously validated, and the specific methods for identifying and isolating the CSCs from the parental cancer population have also been rapidly developed in recent years. This review aims to provide an overview of recent research progress of Chinese medicines (CMs) and their active compounds in inhibiting tumor progression by targeting CSCs. A great deal of CMs and their active compounds, such as Antrodia camphorate, berberine, resveratrol, and curcumin have been shown to regress CSCs, in terms of reversing drug resistance, inducing cell death and inhibiting cell proliferation as well as metastasis. Furthermore, one of the active compounds in coptis, berbamine may inhibit tumor progression by modulating microRNAs to regulate CSCs. The underlying molecular mechanisms and related signaling pathways involved in these processes were also discussed and concluded in this paper. Overall, the use of CMs and their active compounds may be a promising therapeutic strategy to eradicate cancer by targeting CSCs. However, further studies are needed to clarify the potential of clinical application of CMs and their active compounds as complementary and alternative therapy in this field.

miR-98 functions as a tumor suppressor in salivary adenoid cystic carcinomas

Purpose

miR-98, a member of the let-7 family of microRNAs, is downregulated in many malignant tumors and has been correlated with tumor progression. However, the roles of miR-98 in salivary adenoid cystic carcinomas (SACCs) are still unclear. Thus, we explored the role of miR-98 in the pathogenesis of SACCs.

Methods

Reverse transcription-polymerase chain reaction was used to quantify miR-98 expression in SACC cell lines as well as in the primary tumors and adjacent tissues. Target gene prediction was carried out using softwares such as miRanda, PicTar, and TargetScan, and the neuroblastoma RAS viral oncogene homologue (N-RAS) was chosen as a potential target gene. Subsequently, the regulatory role of miR-98 on N-RAS expression was examined by Western blotting and immunofluorescence assays. N-RAS expression was detected in SACC tissues and SACC cell lines using immunohistochemistry and Western blot, respectively. Furthermore, the associations between N-RAS expression and clinicopathological features were analyzed. Finally, the effects of miR-98 on the proliferation and metastasis of SACC cell lines were determined.

Results

miR-98 was downregulated in primary tissues and ACC-M cells. Meanwhile, N-RAS expression was significantly higher in SACC tissues than that in the adjacent tissues, and its overexpression was significantly associated with the clinical stage and tumor size. In addition, the overexpression of miR-98 in ACC-M cells inhibited cell proliferation, invasion, and migration in vitro. It also significantly decreased the expression of N-RAS and inhibited signaling through the PI3K/AKT and MAPK/ERK pathways.

Conclusion

These results indicate that miR-98 possibly acts as a tumor suppressor in SACC by negatively regulating the oncogene N-RAS.

Overexpression of microRNA-5100 decreases the aggressive phenotype of pancreatic cancer cells by targeting PODXL

Metastasis is the main cause of cancer-associated death, and metastasis of pancreatic cancer remains difficult to treat because of its aggressiveness. MicroRNAs (miRNAs) play crucial roles in the regulation of various human transcripts, and many miRNAs have been reported to correlate with cancer metastasis. We identified an anti-metastatic miRNA, miR-5100, by investigating differences in miRNA profiling between highly metastatic pancreatic cancer cells and their parental cells. Overexpression of miR-5100 inhibited colony formation (P<0.05), cell migration (P<0.0001) and invasion (P<0.0001) of pancreatic cancer cells. In addition, we identified a possible target of miR-5100, podocalyxin-like 1 (PODXL), and demonstrated miR-5100 directly binds to the 3' untranslated region of PODXL and post-transcriptionally regulates its expression in pancreatic cancer cells. Silencing PODXL resulted in diminished cell migration (P<0.0001) and invasion (P<0.05). We also clarified the close relationship between expression of PODXL in human pancreatic cancer specimens and liver metastasis (P=0.0003), and determined that post-operative survival was longer in the low-PODXL expression group than in the high-PODXL expression group (P<0.05). These results indicate that miR-5100 and PODXL have considerable therapeutic potential for anti-metastatic therapy and could be potential indicators for cancer metastases in patients with pancreatic cancer.

Abrogating the interplay between IGF2BP1, 2 and 3 and IGF1R by let-7i arrests hepatocellular carcinoma growth

IGF2BP 1, 2 and 3 control the fate of many transcripts. Immunoprecipitation studies demonstrated the IGF2BPs to bind to IGF1R mRNA, and our laboratory has recently shown them to post-transcriptionally regulate IGF1R. This study sought to identify a microRNA regulating the IGF2BPs and consequently IGF1R. All three IGF2BPs were among the top-ranked predicted targets of let-7i. Let-7i was downregulated in HCC tissues, and transfection of HuH-7 with let-7i inhibited malignant cell behaviors and decreased IGF2BPs transcripts. Direct binding of let-7i to IGF2BP2 and IGF2BP3 3'UTRs was confirmed, and the effect of let-7i caused a decrease in the IGF2BPs' target gene, the IGF1R. IGF1R mRNA was inversely correlated with let-7i in HCC tissues and was reduced upon let-7i transfection into HuH-7. Reporter assays validated IGF1R as a target of let-7i. Therefore, let-7i may control HCC tumorigenesis by regulating IGF1R directly and indirectly by interrupting the interplay between IGF1R and the IGF2BPs.

Biological and therapeutic activities, and anticancer properties of curcumin

Curcumin (diferuloylmethane) is a polyphenol derived from the Curcuma longa plant. Curcumin has been used extensively in Ayurvedic medicine, as it is nontoxic and exhibits a variety of therapeutic properties, including antioxidant, analgesic, anti-inflammatory and antiseptic activities. Recently, certain studies have indicated that curcumin may exert anticancer effects in a variety of biological pathways involved in mutagenesis, apoptosis, tumorigenesis, cell cycle regulation and metastasis. The present study reviewed previous studies in the literature, which support the therapeutic activity of curcumin in cancer. In addition, the present study elucidated a number of the challenges concerning the use of curcumin as an adjuvant chemotherapeutic agent. All the studies reviewed herein suggest that curcumin is able to exert anti-inflammatory, antiplatelet, antioxidative, hepatoprotective and antitumor activities, particularly against cancers of the liver, skin, pancreas, prostate, ovary, lung and head neck, as well as having a positive effect in the treatment of arthritis.

MiR-181a-5p inhibits cell proliferation and migration by targeting Kras in non-small cell lung cancer A549 cells

MicroRNAs play important roles in carcinogenesis and tumor progress. Lung cancer is the leading cause of cancer mortality worldwide. In this study, the function of miR-181a-5p was investigated in non-small-cell lung cancer (NSCLC). Results showed that miR-181a-5p was significantly decreased in NSCLC tissues and cell lines. The proliferation and migration of A549 cells transfected with miR-181a-5p mimic was significantly inhibited. Luciferase activity assay results demonstrated that two binding sites of Kras could be directly targeted by miR-181a-5p. Furthermore, Kras was down-regulated by miR-181a-5p at both transcriptional and translational levels. SiRNA-mediated Kras down-regulation could mimic the effects of miR-181a-5p mimic in A549 cells. Our findings suggest that miR-181a-5p plays a potential role in tumor suppression by partially targeting Kras and has the potential therapeutic application in NSCLC patients.

Impact of Nutrition on Non-Coding RNA Epigenetics in Breast and Gynecological Cancer

Cancer is the second leading cause of death in females. According to the American Cancer Society, there are 327,660 new cases in breast and gynecological cancers estimated in 2014, placing emphasis on the need for cancer prevention and new cancer treatment strategies. One important approach to cancer prevention involves phytochemicals, biologically active compounds derived from plants. A variety of studies on the impact of dietary compounds found in cruciferous vegetables, green tea, and spices like curry and black pepper have revealed epigenetic changes in female cancers. Thus, an important emerging topic comprises epigenetic changes due to the modulation of non-coding RNA levels. Since it has been shown that non-coding RNAs such as microRNAs and long non-coding RNAs are aberrantly expressed in cancer, and furthermore are linked to distinct cancer phenotypes, understanding the effects of dietary compounds and supplements on the epigenetic modulator non-coding RNA is of great interest. This article reviews the current findings on nutrition-induced changes in breast and gynecological cancers at the non-coding RNA level.

The emerging role of microRNAs and nutrition in modulating health and disease

Understanding the molecular mechanisms that inform how diet and dietary supplements influence health and disease is an active research area. One such mechanism concerns the role of diet in modulating the activity and function of microRNAs (miRNAs). miRNAs are small noncoding RNA molecules that are involved in posttranscriptional gene silencing and have been shown to control gene expression in diverse biological processes including development, differentiation, cell proliferation, metabolism, and inflammation as well as in human diseases. Recent evidence described in this review highlights how dietary factors may influence cancer, cardiovascular disease, type 2 diabetes mellitus, obesity, and nonalcoholic fatty liver disease through modulation of miRNA expression. Additionally, circulating miRNAs are emerging as putative biomarkers of disease, susceptibility, and perhaps dietary exposure. Research needs to move beyond associations in cells and animals to understanding the direct effects of diet and dietary supplements on miRNA expression and function in human health and disease.

Molecular targets of naturopathy in cancer research: bridge to modern medicine

The relevance of naturopathy (defined as the practice of medicine for the treatment of human diseases with natural agents) in human cancer is beginning to be appreciated, as documented by renewed interest in nutraceutical research, the natural anticancer agents of dietary origin. Because of their pleiotropic effects and the ability to modulate multiple signaling pathways, which is a good attribute of natural agents, nutraceuticals have frequently been demonstrated to re-sensitize drug-resistant cancers. The effectiveness of nutraceuticals can be further enhanced if the tools for the relative assessment of their molecular targets are readily available. Such information can be critical for determining their most effective uses. Here, we discuss the anticancer potential of nutraceuticals and the associated challenges that have interfered with their translational potential as a naturopathic approach for the management of cancers. In the years to come, an efficient screening and assessment of molecular targets will be the key to make rapid progress in the area of drug design and discovery, especially focusing on evidence-based development of naturopathy for the treatment of human malignancies.

Curcumin: a potential candidate in prevention of cancer via modulation of molecular pathways

Cancer is the most dreadful disease worldwide in terms of morbidity and mortality. The exact cause of cancer development and progression is not fully known. But it is thought that cancer occurs due to the structural and functional changes in the genes. The current approach to cancer treatment based on allopathic is expensive, exhibits side effects; and may also alter the normal functioning of genes. Thus, a safe and effective mode of treatment is needed to control the cancer development and progression. Some medicinal plants provide a safe, effective and affordable remedy to control the progression of malignant cells. The importance of medicinal plants and their constituents has been documented in Ayurveda, Unani medicine, and various religious books. Curcumin, a vital constituent of the spice turmeric, is an alternative approach in the prevention of cancer. Earlier studies have shown the effect of curcumin as an antioxidant, antibacterial, antitumor and it also has a noteworthy role in the control of different diseases. In this review, we summarize the understanding of chemopreventive effects of curcumin in the prevention of cancer via the regulation of various cell signaling and genetic pathways.

Differentially expressed miRNAs in cancer-stem-like cells: markers for tumor cell aggressiveness of pancreatic cancer

Pancreatic cancer (PC) is one of the most deadly cancers. The higher mortality is in part due to treatment resistance and early onset of metastasis. The existence of cancer-stem-like cells (CSLCs) has been widely accepted to be responsible for tumor aggressiveness in PC. Emerging evidence suggests that CSLCs have the capacity for increased cell growth, cell migration/invasion, metastasis, and treatment resistance, which leads to poor clinical outcome. However, the molecular role of CSLCs in tumor development and progression is poorly understood. Therefore, mechanistic understanding, and targeted killing of CSLCs may provide a newer therapeutic strategy for the treatment of PC. It has been well accepted that microRNAs (miRNAs) play critical roles during tumor development and progression through deregulation of multiple genes. Moreover, deregulated expression of miRNAs may also play a key role in the regulation of CSLC characteristics and functions. Here we show that isolated CD44(+)/CD133(+)/EpCAM(+) cells (triple-marker-positive cells) from human PC cell lines, MiaPaCa-2 and L3.6pl cells, display aggressive characteristics, such as increased cell growth, clonogenicity, cell migration, and self-renewal capacity, which is consistent with overexpression of CSLC signatures/markers. We also found deregulated expression of over 400 miRNAs, including let-7, miR-30, miR-125b, and miR-335, in CSLCs. As a proof-of-concept, knockdown of miR-125b resulted in the inhibition of tumor cell aggressiveness of CSLCs (triple-marker-positive cells), consistent with the downregulation of CD44, EpCAM, EZH2, and snail. These results clearly suggest the importance of miRNAs in the regulation of CSLC characteristics, and may serve as novel targets for therapy.

Deregulation of miR-146a expression in a mouse model of pancreatic cancer affecting EGFR signaling

Aberrant expression of microRNAs (miRNAs) plays important roles in the development and progression of pancreatic cancer (PC). Expression analysis of miR-146a in human PC tissues showed decreased expression in about 80% of samples compared to corresponding non-cancerous tissue. Moreover, expression of miR-146a in eight PC cell lines, and in pancreatic tissues obtained from transgenic mouse models of K-Ras (K), Pdx1-Cre (C), K-Ras;Pdx1-Cre (KC) and K-Ras;Pdx1-Cre;INK4a/Arf (KCI), showed down-regulation of miR-146a expression in KCI mice which was in part led to over-expression of its target gene, epidermal growth factor receptor (EGFR). Treatment of PC cells with CDF, a novel synthetic compound, led to re-expression of miR-146a, resulting in the down-regulation of EGFR expression. Moreover, re-expression of miR-146a by stable transfection or treatment with CDF in vivo (xenograft animal model) resulted in decreased tumor growth which was consistent with reduced EGFR, ERK1, ERK2, and K-Ras expression. Further knock-down of miR-146a in AsPC-1 cells led to the up-regulation of EGFR expression and showed increased clonogenic growth. In addition, knock-down of EGFR by EGFR siRNA transfection of parental AsPC-1 cells and AsPC-1 cells stably transfected with pre-miR-146a resulted in decreased invasive capacity, which was further confirmed by reduced luciferase activity in cells transfected with pMIR-Luc reporter vector containing miR-146a binding site. Collectively, these results suggest that the loss of expression of miR-146a is a fundamental mechanism for over-expression of EGFR signaling and that re-expression of miR-146a by CDF treatment could be useful in designing personalized strategy for the treatment of human PC.

MicroRNA143 and tumors of the digestive system

Recent studies have found that microRNAs have functions analogous to oncogenes or tumor suppressor genes and are important molecules in tumor occurrence and development. In particular, downregulation of microRNA-143 expression in tumors of the digestive system can inhibit tumor proliferation, infiltration and metastasis via regulation of its target genes. In this paper, we review the latest research progress in understanding the role of microRNA-143 in the digestive system.

Epigenetic regulation of miRNA-cancer stem cells nexus by nutraceuticals

Nutraceuticals, the bioactive food components represented by many naturally occurring dietary compounds, have been investigated for a few decades for their numerous beneficial effects, including their anticancer properties. The initial interest in the cancer-preventing/therapeutic ability of these agents was based on their ability to affect multiple signaling pathways that are deregulated in cancer cells. With a shift in the focus of cancer research to the emerging areas such as epigenetic regulation, microRNAs (miRNAs) and the cancer stem cells (CSCs), nutraceuticals initially appeared out of place. However, research investigations over the last several years have slowly but firmly presented evidence that supports a relevance of these agents in modern day research. While nutraceuticals are increasingly being realized to alter miRNA/CSCs expression and function, the molecular mechanism(s) are not very clearly understood. Epigenetic regulation is one mechanism by which these agents exert their anticancer effects. In this focused mini review, we summarize our current understanding of epigenetic regulation of miRNAs and CSCs by nutraceuticals. We discuss both direct and indirect evidences that support such an activity of these compounds.

Fulvestrant increases gefitinib sensitivity in non-small cell lung cancer cells by upregulating let-7c expression

Patients with non-small cell lung cancer (NSCLC) who have activating epidermal growth factor receptor (EGFR) mutations benefit from treatment with EGFR-tyrosine kinase inhibitors (EGFR-TKIs), namely, gefitinib and erlotinib. However, these patients eventually develop resistance to EGFR-TKIs. About 50% of this acquired resistance may be the result of a secondary mutation in the EGFR gene, such as the one corresponding to T790M. In our previous study, we found that combined treatment with fulvestrant and gefitinib decreases the proliferation of H1975 NSCLC cells, compared to treatment with either fulvestrant or gefitinib alone; however, the molecular mechanism for the improved effects of the combination treatment are still unknown. In this study, we confirmed that fulvestrant increases the gefitinib sensitivity of H1975 cells and found that let-7c was most upregulated in the fulvestrant-treated cells. Our data revealed that let-7c increases gefitinib sensitivity by repressing RAS and inactivating the phosphoinositide 3-kinase (PI3K)/AKT and mitogen-activated extracellular signal-regulated kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling pathways. Taken together, our findings suggest that let-7c plays an important role in fulvestrant-induced upregulation of gefitinib sensitivity in H1975 cells.

Targeting CSC-related miRNAs for cancer therapy by natural agents

The theory of cancer stem cells (CSCs) has provided evidence on fundamental clinical implications because of the involvement of CSCs in cell migration, invasion, metastasis, and treatment resistance, which leads to the poor clinical outcome of cancer patients. Therefore, targeting CSCs will provide a novel therapeutic strategy for the treatment and/or prevention of tumors. However, the regulation of CSCs and its signaling pathways during tumorigenesis are not well understood. MicroRNAs (miRNAs) have been proved to act as key regulators of the post-transcriptional regulation of genes, which involve in a wide array of biological processes including tumorigenesis. The altered expressions of miRNAs are associated with poor clinical outcome of patients diagnosed with a variety of tumors. Therefore, emerging evidence strongly suggest that miRMAs play critical roles in tumor development and progression. Emerging evidence also suggest that miRNAs participate in the regulation of tumor cell growth, migration, invasion, angiogenesis, drug resistance, and metastasis. Moreover, miRNAs such as let-7, miR-21, miR-22, miR-34, miR-101, miR-146a, and miR-200 have been found to be associated with CSC phenotype and function mediated through targeting oncogenic signaling pathways. In this article, we will discuss the role of miRNAs in the regulation of CSC phenotype and function during tumor development and progression. We will also discuss the potential role of naturally occurring agents (nutraceuticals) as potent anti-tumor agents that are believed to function by targeting CSC-related miRNAs.

Effects of dietary phytophenols on the expression of microRNAs involved in mammalian cell homeostasis

Besides synthesizing nutritive substances (proteins, fats and carbohydrates) for energy and growth, plants produce numerous non-energetic so-called secondary metabolites (mainly polyphenols) that allow them to protect themselves against infections and other types of hostile environments. Interestingly, these polyphenols often provide cells with valuable bioactive properties for the maintenance of their functions and homeostasis (signaling, gene regulation, protection against acquired or infectious diseases, etc.) both in humans and animals. Namely, from a nutritional point of view, and based on epidemiological data, it is now well accepted that the regular consumption of green vegetables, fruits and fibers has protective effects against the onset of cancer as well as of inflammatory, neurodegenerative, metabolic and cardiovascular diseases, and consequently increases the overall longevity. In particular, grapevine plants produce large amounts of a wide variety of polyphenols. The most prominent of those-resveratrol-has been shown to impair or delay cardiovascular alterations, cancer, inflammation, aging, etc. Until recently, the molecular bases of the pleiotropic effects of resveratrol remained largely unclear despite numerous studies on a variety of signaling pathways and the transcriptional networks that they control. However, it has been recently proposed that the protective properties of resveratrol may arise from its modulation of small non-coding regulatory RNAs, namely microRNAs. The aim of this review is to present up-to-date data on the control of microRNA expression by dietary phytophenols in different types of human cells, and their impact on cell differentiation, cancer development and the regulation of the inflammatory response.

Perspectives on new synthetic curcumin analogs and their potential anticancer properties

Curcumin is the active component of dried rhizome of Curcuma longa, a perennial herb belonging to ginger family, cultivated extensively in south and southeastern tropical Asia. It is widely consumed in the Indian subcontinent, south Asia and Japan in traditional food recipes. Extensive research over last few decades has shown that curcumin is a potent anti-inflammatory agent with powerful therapeutic potential against a variety of cancers. It suppresses proliferation and metastasis of human tumors through regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases and other enzymes. It induces apoptotic cell death and also inhibits proliferation of cancer cells by cell cycle arrest. Pharmacokinetic data has shown that curcumin undergoes rapid metabolism leading to glucuronidation and sulfation in the liver and excretion in the feces, which accounts for its poor systemic bioavailability. The compound has, therefore, been formulated and administered using different drug delivery systems such as liposomes, micelles, polysaccharides, phospholipid complexes and nanoparticles that can overcome the limitation of bioavailability to some extent. Attempts to avoid rapid metabolism of curcumin until now have been met with limited success. This has prompted researchers to look for new synthetic curcumin analogs in order to overcome the drawbacks of limited bioavailability and rapid metabolism, and gain efficacy with reduced toxicity. In this review we provide a summarized account of novel synthetic curcumin formulations and analogs, and the recent progress in the field of cancer prevention and treatment.

Perspectives on new synthetic curcumin analogs and their potential anticancer properties

Curcumin is the active component of dried rhizome of Curcuma longa, a perennial herb belonging to ginger family, cultivated extensively in south and southeastern tropical Asia. It is widely consumed in the Indian subcontinent, south Asia and Japan in traditional food recipes. Extensive research over last few decades has shown that curcumin is a potent anti-inflammatory agent with powerful therapeutic potential against a variety of cancers. It suppresses proliferation and metastasis of human tumors through regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases and other enzymes. It induces apoptotic cell death and also inhibits proliferation of cancer cells by cell cycle arrest. Pharmacokinetic data has shown that curcumin undergoes rapid metabolism leading to glucuronidation and sulfation in the liver and excretion in the feces, which accounts for its poor systemic bioavailability. The compound has, therefore, been formulated and administered using different drug delivery systems such as liposomes, micelles, polysaccharides, phospholipid complexes and nanoparticles that can overcome the limitation of bioavailability to some extent. Attempts to avoid rapid metabolism of curcumin until now have been met with limited success. This has prompted researchers to look for new synthetic curcumin analogs in order to overcome the drawbacks of limited bioavailability and rapid metabolism, and gain efficacy with reduced toxicity. In this review we provide a summarized account of novel synthetic curcumin formulations and analogs, and the recent progress in the field of cancer prevention and treatment.

Difluorinated-curcumin (CDF) restores PTEN expression in colon cancer cells by down-regulating miR-21

Despite recent advancement in medicine, nearly 50% of patients with colorectal cancer show recurrence of the disease. Although the reasons for the high relapse are not fully understood, the presence of chemo- and radiotherapy-resistant cancer stem/stem-like cells, where many oncomirs like microRNA-21 (miR-21) are upregulated, could be one of the underlying causes. miR-21 regulates the processes of invasion and metastasis by downregulating multiple tumor/metastatic suppressor genes including PTEN (phosphatase and tensin homolog). Tumor suppressor protein PTEN controls self-renewal of stem cells. Indeed, our current data demonstrate a marked downregulation of PTEN in SCID mice xenografts of miR-21 over-expressing colon cancer HCT116 cells. Colonospheres that are highly enriched in cancer stem/stem like cells reveal increased miR-21 expression and decreased PTEN. Difluorinated curcumin (CDF), a novel analog of the dietary ingredient curcumin, which has been shown to inhibit the growth of 5-Flurouracil + Oxaliplatin resistant colon cancer cells, downregulated miR-21 in chemo-resistant colon cancer HCT116 and HT-29 cells and restored PTEN levels with subsequent reduction in Akt phosphorylation. Similar results were also observed in metastatic colon cancer SW620 cells. Since PTEN-Akt confers drug resistance to different malignancies including colorectal cancer, our observation of normalization of miR-21-PTEN-Akt pathway by CDF suggests that the compound could be a potential therapeutic agent for chemotherapy-resistant colorectal cancer.

Clinical advances in molecular biomarkers for cancer diagnosis and therapy

Cancer diagnosis is currently undergoing a paradigm shift with the incorporation of molecular biomarkers as part of routine diagnostic panel. The molecular alteration ranges from those involving the DNA, RNA, microRNAs (miRNAs) and proteins. The miRNAs are recently discovered small non-coding endogenous single-stranded RNAs that critically regulates the development, invasion and metastasis of cancers. They are altered in cancers and have the potential to serve as diagnostic markers for cancer. Moreover, deregulating their activity offers novel cancer therapeutic approaches. The availability of high throughput techniques for the identification of altered cellular molecules allowed their use in cancer diagnosis. Their application to a variety of body specimens from blood to tissues has been helpful for appreciating their use in the clinical context. The development of innovative antibodies for immunohistochemical detection of proteins also assists in diagnosis and risk stratification. Overall, the novel cancer diagnostic tools have extended their application as prognostic risk factors and can be used as targets for personalized medicine.

miR145 targets the SOX9/ADAM17 axis to inhibit tumor-initiating cells and IL-6-mediated paracrine effects in head and neck cancer

ALDH1(+)CD44(+) cells are putative tumor-initiating cells (TIC) in head and neck squamous cell carcinomas (HNC). miR-145 regulates tumorigenicity in various cancers but the breadth of its mechanistic contributions and potential therapeutic applications are not completely known. Here, we report that ALDH1(+)CD44(+)-HNC cells express reduced levels of miR145. SPONGE-mediated inhibition of miR-145 (Spg-miR145) was sufficient to drive tumor-initiating characteristics in non-TICs/ALDH1(-)CD44-negative HNC cells. Mechanistic analyses identified SOX9 and ADAM17 as two novel miR145 targets relevant to this process. miR-145 expression repressed TICs in HNC in a manner associated with SOX9 interaction with the ADAM17 promoter, thereby activating ADAM17 expression. Notably, the SOX9/ADAM17 axis dominated the TIC-inducing activity of miR-145. Either miR-145 suppression or ADAM17 overexpression in non-TICs/ALDH1(-)CD44(-)-HNC cells increased expression and secretion of interleukin (IL)-6 and soluble-IL-6 receptor (sIL-6R). Conversely, conditioned medium from Spg-miR145-transfected non-TICs/ALDH1(-)CD44(-)-HNC cells was sufficient to confer tumor-initiating properties in non-TICs/ALDH1(-)CD44(-)-HNC and this effect could be abrogated by an IL-6-neutralizing antibody. We found that curcumin administration increased miR-145 promoter activity, thereby decreasing SOX9/ADAM17 expression and eliminating TICs in HNC cell populations. Delivery of lentivral-miR145 or orally administered curcumin blocked tumor progression in HNC-TICs in murine xenotransplant assays. Finally, immunohistochemical analyses of patient specimens confirmed that an miR-145(low)/SOX9(high)/ADAM17(high) phenotype correlated with poor survival. Collectively, our results show how miR-145 targets the SOX9/ADAM17 axis to regulate TIC properties in HNC, and how altering this pathway may partly explain the anticancer effects of curcumin. By inhibiting IL-6 and sIL-6R as downstream effector cytokines in this pathway, miR-145 seems to suppress a paracrine signaling pathway in the tumor microenvironment that is vital to maintain TICs in HNC.

Systems and Network Pharmacology Approaches to Cancer Stem Cells Research and Therapy

The cancer stem cell (CSC) hypothesis is increasingly being accepted as a model to explain for the functional heterogeneity that is commonly observed in solid tumors. According to this hypothesis, there exists a hierarchical organization of cells within the tumor, in which a differential subpopulation of stem-like cells is responsible for sustaining and recurrence of tumor growth. CSCs have been shown to exist in a variety of solid tumors especially those with known resistant phenotypes such as breast, prostate and pancreatic adenocarcinoma (PDAC). In all these models, the commonality of deregulation of three crucial pathways; Wnt, notch and hedgehog that maintain CSC self-renewal capacity is emerging. Collectively these major pathways and have been linked to the observed resistance of CSC to chemotherapy and radiotherapy. The existing lack of knowledge and our incomplete understanding of the molecular signatures associated with CSCs highlight the need for better approaches in both isolation and identification of unique pathways associated with these cells. In this direction, computational biology, especially systems and network approaches, have proven to be of great utility in unraveling pathway complexities such as those associated with CSCs. With highlights on the most up-to-date molecular, network, cellular, clinical, and therapeutic cancer research findings, this article tends to provide a wealth of insights on systems and network biology approaches to CSC marker identification, the mechanism through which they evade treatment as well as therapeutic approaches that will help in conquering these elusive cells in incurable and refractory malignancies.

Curcumin, a component of turmeric: from farm to pharmacy

Curcumin, an active polyphenol of the golden spice turmeric, is a highly pleiotropic molecule with the potential to modulate the biological activity of a number of signaling molecules. Traditionally, this polyphenol has been used in Asian countries to treat such human ailments as acne, psoriasis, dermatitis, and rash. Recent studies have indicated that curcumin can target newly identified signaling pathways including those associated with microRNA, cancer stem cells, and autophagy. Extensive research from preclinical and clinical studies has delineated the molecular basis for the pharmaceutical uses of this polyphenol against cancer, pulmonary diseases, neurological diseases, liver diseases, metabolic diseases, autoimmune diseases, cardiovascular diseases, and numerous other chronic diseases. Multiple studies have indicated the safety and efficacy of curcumin in numerous animals including rodents, monkeys, horses, rabbits, and cats and have provided a solid basis for evaluating its safety and efficacy in humans. To date, more than 65 human clinical trials of curcumin, which included more than 1000 patients, have been completed, and as many as 35 clinical trials are underway. Curcumin is now used as a supplement in several countries including the United States, India, Japan, Korea, Thailand, China, Turkey, South Africa, Nepal, and Pakistan. In this review, we provide evidence for the pharmaceutical uses of curcumin for various diseases.

The role of cancer stem cells and miRNAs in defining the complexities of brain metastasis

Researchers and clinicians have been challenged with the development of therapies for the treatment of cancer patients whose tumors metastasized to the brain. Among the most lethal weapons known today, current management of brain metastases involves multiple therapeutic modalities that provide little, if any, for improving the quality of life and overall survival. Recently the role of cancer stem cells (CSCs) in the development of cancer has been studied extensively, and thus its role in the prognosis, diagnosis, and treatment is now being investigated even in the realm of brain metastasis (BM). Recognizing the molecular make-up of CSCs as well as understanding the role of these cells in resistance to treatment modalities is expected to benefit cancer patients. Additionally, past decade has witnessed an increase in awareness and understanding of the role of microRNAs (miRNAs) in various cancer types, and the deregulation miRNAs are critically important for the regulation of genes during the development and progression of human malignancies. The role miRNAs in BM is being investigated, and has also shown tremendous promise for future research. In this review, we discuss the problem and lethality of brain metastases and the current state of management, and further provide insight into novel avenues that are worth considering including the biological complexities of CSCs and miRNAs for designing novel therapies.

Developing microRNA therapeutics: approaching the unique complexities

MicroRNAs are endogenous small non-coding RNAs that regulate gene expression by interfering with translation or stability of target transcripts. The importance of microRNAs for maintaining biological functions is illustrated by the fact that microRNAs are exploited in nature to regulate phenotypes, and by the diverse disease phenotypes that result when microRNAs are mutated or improperly expressed. Disease-associated microRNAs might therefore represent a new class of therapeutic targets. With the recent demonstration that inhibition of miR-122 reduces viral load in hepatitis C patients, microRNA modulators are no longer merely theoretical, but rather, have become strong candidate therapeutics. The complexity of microRNA biology offers a novel mechanism of action for therapeutic intervention but also poses unique challenges for the development of therapeutic modulators as drugs.

The biological kinship of hypoxia with CSC and EMT and their relationship with deregulated expression of miRNAs and tumor aggressiveness

Hypoxia is one of the fundamental biological phenomena that are intricately associated with the development and aggressiveness of a variety of solid tumors. Hypoxia-inducible factors (HIF) function as a master transcription factor, which regulates hypoxia responsive genes and has been recognized to play critical roles in tumor invasion, metastasis, and chemo-radiation resistance, and contributes to increased cell proliferation, survival, angiogenesis and metastasis. Therefore, tumor hypoxia with deregulated expression of HIF and its biological consequence lead to poor prognosis of patients diagnosed with solid tumors, resulting in higher mortality, suggesting that understanding of the molecular relationship of hypoxia with other cellular features of tumor aggressiveness would be invaluable for developing newer targeted therapy for solid tumors. It has been well recognized that cancer stem cells (CSCs) and epithelial-to-mesenchymal transition (EMT) phenotypic cells are associated with therapeutic resistance and contribute to aggressive tumor growth, invasion, metastasis and believed to be the cause of tumor recurrence. Interestingly, hypoxia and HIF signaling pathway are known to play an important role in the regulation and sustenance of CSCs and EMT phenotype. However, the molecular relationship between HIF signaling pathway with the biology of CSCs and EMT remains unclear although NF-κB, PI3K/Akt/mTOR, Notch, Wnt/β-catenin, and Hedgehog signaling pathways have been recognized as important regulators of CSCs and EMT. In this article, we will discuss the state of our knowledge on the role of HIF-hypoxia signaling pathway and its kinship with CSCs and EMT within the tumor microenvironment. We will also discuss the potential role of hypoxia-induced microRNAs (miRNAs) in tumor development and aggressiveness, and finally discuss the potential effects of nutraceuticals on the biology of CSCs and EMT in the context of tumor hypoxia.

Pancreatic cancer chemoprevention by phytochemicals

Pancreatic cancer is fourth leading cause of cancer-related deaths in the United States of America. In spite of recent advances in the current therapeutic modalities such as surgery, radiation and chemotherapy patients, the average five year survival rate remains still less than 5%. Recently, compounds from natural sources receive ample of attention as anti-cancer agents. Many epidemiological studies published over the past few decades provide a strong correlation between consumption of vegetables, fruits or plant derived products and reduced incidence of cancer. The present review focuses on the potential antitumor effects of various natural products.

miR-143 inhibits the metastasis of pancreatic cancer and an associated signaling pathway

Pancreatic cancer is characterized by early metastasis and high mortality. In this study, the role of miR-143 in invasion and metastasis was investigated in pancreatic cancer cells. miR-143 expression was established by an adenovirus-carried miR-143 expression cassette. mRNA and protein levels of gene expression were examined by RT-PCR and Western blot assay, respectively. Rho GTPases activity was measured by the pull down assay. The role of miR-143 in migration and invasion of Panc-1 cells was tested in vitro. The antimetastatic effect of miR-143 was tested in a liver metastasis model, while its antitumor growth effect was tested in a xenograft Panc-1 tumor model. Results demonstrated that ARHGEF1 (GEF1), ARHGEF2 (GEF2), and K-RAS genes are the targets of miR-143. miR-143 expression significantly decreased mRNA and protein levels of GEF1, GEF2, and K-RAS genes; lowered the constitutive activities of RhoA, Rac1, and Cdc42 GTPases; decreased the protein levels of MMP-2 and MMP-9; but significantly increased the protein level of E-cadherin. miR-143 expression also significantly inhibited the migration and invasion of Panc-1 cells in vitro, liver metastasis, and xenograft tumor growth in vivo. Our study suggested that miR-143 plays a central role in the invasion and metastasis of pancreatic cancer and miR-143 is a potential target for pancreatic cancer therapy.

Expression of miR-34 is lost in colon cancer which can be re-expressed by a novel agent CDF

Background

Colorectal Cancer (CRC) is one of the leading causes of death worldwide. Numerous cellular events, including deregulated expression of microRNAs (miRNAs), specifically the family of miR-34 consisting of miR-34a, b and c, is known to regulate the processes of growth and metastasis.

Methods

We evaluated the expression of miR-34 in formalin-fixed paraffin-embedded (FFPE) human colon cancer tissue specimens compared to normal colonic mucosa. Moreover, we also assessed the expression of miR-34 in colon cancer cell lines treated with our newly developed synthetic analogue of curcumin referred as difluorinated curcumin (CDF) compared to well known inhibitor of methyl transferase.

Results

We found that the expression of miR-34a and miR-34c was down-regulated in colon cancer specimens compared to normal colonic mucosa and the loss of expression was also consistent with data from colon cancer cell lines. This down-regulation was attributed to promoter hypermethylation, because we found that the treatment of colon cancer cells with 5-aza-2´-deoxycytidine, a methyltransferase inhibitor, markedly induced the levels of miR-34a and miR-34c expression. Likewise, CDF was very effective in the re-expression of miR-34a and miR-34c, which was consistent with inhibition of cell growth of both chemo-sensitive and chemo-resistant colon cancer cells. The re-expression of miR-34 led to a marked reduction in the expression of its target gene, Notch-1.

Conclusion

The loss of expression of miR-34 in colon cancer is in part due to promoter hypermethylation of miR-34, which can be re-expressed with our novel agent CDF, suggesting that CDF could be a novel demethylating agent for restoring the expression of miR-34 family, and thus CDF could become a newer therapeutic agent for the treatment of colon cancer.

Hypoxia induced aggressiveness of prostate cancer cells is linked with deregulated expression of VEGF, IL-6 and miRNAs that are attenuated by CDF

Tumor hypoxia with deregulated expression of hypoxia inducing factor (HIF) and its biological consequence leads to poor prognosis of patients diagnosed with solid tumors, resulting in higher mortality, suggesting that understanding of the molecular relationship of hypoxia with other cellular features of tumor aggressiveness would be invaluable for developing newer targeted therapy for solid tumors. Emerging evidence also suggest that hypoxia and HIF signaling pathways contributes to the acquisition of epithelial-to-mesenchymal transition (EMT), maintenance of cancer stem cell (CSC) functions, and also maintains the vicious cycle of inflammation, all of which contribute to radiation therapy and chemotherapy resistance. However, the detailed mechanisms by which hypoxia/HIF drive these events are not fully understood. Here, we have shown that hypoxia leads to increased expression of VEGF, IL-6, and CSC marker genes such as Nanog, Oct4 and EZH2, and also increased the expression of miR-21, an oncogenic miRNA, in prostate cancer (PCa) cells (PC-3 and LNCaP). The treatment of PCa cells with CDF, a novel Curcumin-derived synthetic analogue previously showed anti-tumor activity in vivo, inhibited the productions of VEGF and IL-6, and down-regulated the expression of Nanog, Oct4, EZH2 mRNAs, as well as miR-21 under hypoxic condition. Moreover, CDF treatment of PCa cells led to decreased cell migration under hypoxic condition. Taken together, these results suggest that the anti-tumor effect of CDF is in part mediated through deregulation of tumor hypoxic pathways, and thus CDF could become useful for cancer therapy.

Re-expression of miR-200 by novel approaches regulates the expression of PTEN and MT1-MMP in pancreatic cancer

Membrane type-1 matrix metalloproteinase (MT1-MMP) is often activated and expressed in tumor cells with significant invasive properties, and is associated with poor prognosis of patients. This could partly be due to deregulated expression of microRNAs (miRNAs) which regulates the expression of MT1-MMP and PTEN (phosphatase and tensin homolog) contributing to tumor invasion and metastasis. We initially compared the expression profile of miR-200 family, PTEN and MT1-MMP expression in six pancreatic cancer (PC) cell lines by qRT-PCR and western blot analysis. We found loss of expression of miR-200a, b and c in chemo-resistant PC cell lines, which was correlated with loss of PTEN and over-expression of MT1-MMP. Based on our initial findings, we chose BxPC-3, MIAPaCa-2 and MIAPaCa-2-GR cells for further mechanistic studies We assessed the effect of two separate novel agents CDF (a synthetic analog of curcumin) and BR-DIM (a natural agent) on PC cells. The expression of miR-200 family and PTEN was significantly re-expressed whereas the expression of MT1-MMP was down-regulated by CDF and BR-DIM treatment. Forced over-expression or silencing of miR-200c, followed by either CDF or BR-DIM treatment of MIAPaCa-2 cells, altered the morphology of cells, wound-healing capacity, colony formation and the expression of MT1-MMP and PTEN. These results provide strong experimental evidence showing that the loss of miR-200 family and PTEN expression and increased level of MT1-MMP leads to aggressive behavior of PC cells, which could be attenuated through re-expression of miR-200c by CDF and/or BR-DIM treatment, suggesting that these agents could be useful for PC treatment.