Reciprocal regulation of microRNA-99a and insulin-like growth factor I receptor signaling in oral squamous cell carcinoma cells

Insulin-like growth factor-independent insulin-like growth factor binding protein 3 promotes cell migration and lymph node metastasis of oral squamous cell carcinoma cells by requirement of integrin β1

Frequent metastasis to the cervical lymph nodes leads to poor survival of patients with oral squamous cell carcinoma (OSCC). To understand the underlying mechanisms of lymph node metastasis, two sublines were successfully isolated from cervical lymph nodes of nude mice through in vivo selection, and identified as originating from poorly metastatic parental cells. These two sublines specifically metastasized to cervical lymph nodes in 83% of mice, whereas OEC-M1 cells did not metastasize after injection into the oral cavity. After gene expression analysis, we identified insulin-like growth factor binding protein 3 (IGFBP3) as one of the significantly up-regulated genes in the sublines in comparison with their parental cells. Consistently, meta-analysis of the public microarray datasets and IGFBP3 immunohistochemical analysis revealed increased both levels of IGFBP3 mRNA and protein in human OSCC tissues when compared to normal oral or adjacent nontumorous tissues. Interestingly, the up-regulated IGFBP3 mRNA expression was significantly associated with OSCC patients with lymph node metastasis. IGFBP3 knockdown in the sublines impaired and ectopic IGFBP3 expression in the parental cells promoted migration, transendothelial migration and lymph node metastasis of orthotopic transplantation. Additionally, ectopic expression of IGFBP3 with an IGF-binding defect sustained the IGFBP3-enhanced biological functions. Results indicated that IGFBP3 regulates metastasis-related functions of OSCC cells through an IGF-independent mechanism. Furthermore, exogenous IGFBP3 was sufficient to induce cell motility and extracellular signal-regulated kinase (ERK) activation. The silencing of integrin β1 was able to impair exogenous IGFBP3-mediated migration and ERK phosphorylation, suggesting a critical role of integrin β1 in IGFBP3-enchanced functions.

Down Regulation of miR-34a and miR-143 May Indirectly Inhibit p53 in Oral Squamous Cell Carcinoma: a Pilot Study

BACKGROUND

Aberrant microRNA expression has been associated with the pathogenesis of a variety of human malignancies including oral squamous cell carcinoma (SCC). In this study, we examined primary oral SCCs for the expression of 6 candidate miRNAs, of which five (miR-34a, miR-143, miR-373, miR-380-5p, and miR- 504) regulate the tumor suppressor TP53 and one (miR-99a) is involved in AKT/mTOR signaling.

MATERIALS AND METHODS

Tumor tissues (punch biopsies) were collected from 52 oral cancer patients and as a control, 8 independent adjacent normal tissue samples were also obtained. After RNA isolation, we assessed the mature miRNA levels of the 6 selected candidates against RNU44 and RNU48 as endogenous controls, using specific TaqMan miRNA assays.

RESULTS

miR-34a, miR-99a, miR-143 and miR-380-5p were significantly down-regulated in tumors compared to controls. Moreover, high levels of miR-34a were associated with alcohol consumption while those of miR-99a and miR-143 were associated with advanced tumor size. No significant difference was observed in the levels of miR-504 between the tumors and controls whereas miR-373 was below the detection level in all but two tumor samples.

CONCLUSIONS

Low levels of miR-380-5p and miR-504 that directly target the 3'UTR of TP53 suggest that p53 may not be repressed by these two miRNAs in OSCC. On the other hand, low levels of miR-34a or miR-143 may relieve MDM4 and SIRT1 or MDM2 respectively, which will sequester p53 indicating an indirect mode of p53 suppression in oral tumors.

Tumour cell-derived WNT5B modulates in vitro lymphangiogenesis via induction of partial endothelial-mesenchymal transition of lymphatic endothelial cells

Metastasis of the cervical lymph nodes frequently leads to poor survival of patients with oral squamous cell carcinoma (OSCC). The underlying mechanisms of lymph node metastasis are unclear. Wingless-type MMTV integration site family, member 5B (WNT5B), one component of the WNT signal pathway, was markedly up-regulated in OSCC sublines with high potential of lymphatic metastasis compared to that in OSCC cells with low nodal metastasis. Increased WNT5B mRNA was demonstrated in human OSCC tissues in comparison with adjacent non-tumorous tissues. Interestingly, the high level of WNT5B protein in serum was associated with lymph node metastasis in OSCC patients. Knockdown of WNT5B expression in OSCC sublines did not affect tumour growth but impaired lymph node metastasis and tumour lymphangiogenesis of orthotopic transplantation. Conditioned medium from WNT5B knockdown cells reduced the tube formation of lymphatic endothelial cells (LECs). In contrast, recombinant WNT5B enhanced the tube formation, permeability and migration of LECs. In LECs stained with phalloidin, the morphology of those treated with recombinant WNT5B changed from flat to spindle-like. Recombinant WNT5B also increased α-smooth muscle actin and inhibited the expression of vascular endothelial-cadherin but retained characteristics of endothelial cells. The results suggest that WNT5B functions in the partial endothelial-mesenchymal transition (EndoMT). Furthermore, WNT5B-induced tube formation was impaired in the LECs following the knockdown of EndoMT-related transcription factor, SNAIL or SLUG. The WNT5B-induced expression of Snail or Slug was abolished by IWR-1-endo and Rac1 inhibitors, which are involved in the WNT/β-catenin and planar cell polarity pathways, respectively. Collectively, the data suggest that WNT5B induces tube formation by regulating the expression of Snail and Slug proteins through activation of canonical and non-canonical WNT signalling pathways.

miR-448 downregulates MPPED2 to promote cancer proliferation and inhibit apoptosis in oral squamous cell carcinoma

The incidence of oral squamous cell carcinoma (OSCC) is continuously increasing while its survival rate has not notably improved. There is a pressing need for improved understanding of the genetic regulation of OSCC tumorigenesis and progression. In this study, the function of miR-448 in the regulation of OSCC growth and its putative target were thoroughly analyzed in vitro. The expression of miR-448 was detected in human OSCC specimens and OSCC cell lines (Cal-27 and Scc-9) by reverse transcription-quantitative polymerase chain reaction. The function of miR-448 was investigated in Cal-27 cells transfected with miR-448 inhibitor, and its putative target determined using a luciferase reporter assay. MTT and wound healing assays and flow cytometry were used to evaluate the effects of miR-448 on OSCC proliferation, metastasis and apoptosis. The level of miR-448 was significantly elevated in human OSCC tissues and the Cal-27 cell line. Suppression of miR-448 expression attenuated cell proliferation and migration, and induced apoptosis of Cal-27 cells. Furthermore, miR-448 bound with the 3'-untranslated region of metallophosphoesterase domain containing 2 (MPPED2) mRNA, thereby reducing the MPPED2 protein level. Thus, it appears that miR-448 acts as a tumor inducer, causing OSCC growth by inhibiting the expression of its target MPPED2. These results demonstrate that miR-448 plays a critical role in OSCC tumorigenesis, and is a potential therapeutic target.

IL-8 induces miR-424-5p expression and modulates SOCS2/STAT5 signaling pathway in oral squamous cell carcinoma

Suppressor of cytokine signaling (SOCS) proteins are negative feedback regulators of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway. Dysregulation of SOCS protein expression in cancers can be one of the mechanisms that maintain STAT activation, but this mechanism is still poorly understood in oral squamous cell carcinoma (OSCC). Here, we report that SOCS2 protein is significantly downregulated in OSCC patients and its levels are inversely correlated with miR‐424‐5p expression. We identified the SOCS2 protein, which modulates STAT5 activity, as a direct target of miR‐424‐5p. The miR‐424‐5p‐induced STAT5 phosphorylation, matrix metalloproteinases (MMPs) expression, and cell migration and invasion were blocked by SOCS2 restoration, suggesting that miR‐424‐5p exhibits its oncogenic activity through negatively regulating SOCS2 levels. Furthermore, miR‐424‐5p expression could be induced by the cytokine IL‐8 primarily through enhancing STAT5 transcriptional activity rather than NF‐κB signaling. Antagomir‐mediated inactivation of miR‐424‐5p prevented the IL‐8‐induced cell migration and invasion, indicating that miR‐424‐5p is required for IL‐8‐induced cellular invasiveness. Taken together, these data indicate that STAT5‐dependent expression of miR‐424‐5p plays an important role in mediating IL‐8/STAT5/SOCS2 feedback loop, and scavenging miR‐424‐5p function using antagomir may have therapeutic potential for the treatment of OSCC.

miR‐424‐5p is overexpressed in OSCC.

miR‐424‐5p directly targets SOCS2, leading to increased cell migration and invasion.

STAT5 activation is required for IL‐8‐mediated miR‐424‐5p transcription.

miR‐424‐5p plays an important role in mediating IL‐8/STAT5/SOCS2 feedback loop.

Claudin 1 Expression Levels Affect miRNA Dynamics in Human Basal-Like Breast Cancer Cells

Deemed a putative tumor suppressor in breast cancer, the tight junction protein claudin 1 has now been shown to be highly expressed in the basal-like molecular subtype. Moreover, recent in vitro studies show that claudin 1 can regulate breast cancer cell motility and proliferation. Herein, we investigated whether microRNA (miRNA) dysregulation is associated with alterations in the level of claudin 1. Using next-generation sequencing (NGS), we identified seven miRNAs (miR-9-5p, miR-9-3p, let-7c, miR-127-3p, miR-99a-5p, miR-129-5p, and miR-146a-5p) that were deregulated as a consequence of claudin 1 overexpression in the MDA-MB231 human breast cancer (HBC) cell line. Most of these miRNAs have been associated with tumor suppression in a variety of cancers, including breast cancer. Moreover, through gene expression profiling analysis, we identified epithelial-mesenchymal transition-related genes, including platelet-derived growth factor receptor-beta (PDGFRB) and cadherin 1 (CDH1, E cadherin), whose downregulation correlated with claudin 1 overexpression. Collectively, we show for the first time that in HBC, claudin 1 can alter the dynamics of a number of miRNAs involved in tumor progression. Our data suggest that the dysregulated expression of these miRNAs, in conjunction with the high claudin 1 levels, could serve as a useful biomarker that identifies a subset of tumors within the poorly characterized basal-like subtype of breast cancer. Further studies are warranted to determine the role of these miRNAs in facilitating the function of claudin 1 in breast cancer.

Could the PI3K canonical pathway be a common link between chronic inflammatory conditions and oral carcinogenesis?

The association between chronic inflammatory disorders and oral carcinogenesis has been both a source of interest and contention. Based upon its central importance in oral carcinogenesis, the finding that the PI3k/Akt/mTOR pathway is activated in oral lichen planus, chronic graft-versus-host disease, and chronic oral candidiasis suggests that it may provide a link between benign and malignant oral conditions. Here, we discuss a possible mechanistic rationale that addresses the activation of this important signaling pathway and its downstream events, while correlating it with the carcinogenic potential of chronic oral disorders.

MicroRNAs as Important Players and Biomarkers in Oral Carcinogenesis

Oral cancer, represented mainly by oral squamous cell carcinoma (OSCC), is the eighth most common type of human cancer worldwide. The number of new OSCC cases is increasing worldwide, especially in the low-income countries, and the prognosis remains poor in spite of recent advances in the diagnostic and therapeutic modalities. MicroRNAs (miRNAs), 18–25 nucleotides long noncoding RNA molecules, have recently gained significant attention as potential regulators and biomarkers for carcinogenesis. Recent data show that several miRNAs are deregulated in OSCC, and they have either a tumor suppressive or an oncogenic role in oral carcinogenesis. This review summarizes current knowledge on the role of miRNAs as tumor promotors or tumor suppressors in OSCC development and discusses their potential value as diagnostic and prognostic markers in OSCC.

Recurrent FGFR3-TACC3 fusion gene in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is one of the most common head and neck malignancies and exhibits regional differences in incidence. Because many fusion genes have been discovered in different types of tumors over the past few years, we aimed to investigate the existence of a fusion gene in primary NPC patients using RNA-seq. In this study, for the first time, we found that fibroblast growth factor receptor 3-transforming acidic coiled-coil-containing protein 3 (FGFR3-TACC3) fusion transcripts are recurrently detected in NPC. The presence of this fusion gene was also detected in head and neck cancer, esophageal squamous cell carcinoma (ESCC), and lung cancer. Furthermore, we found certain new isoforms of the FGFR3-TACC3 fusion transcripts, such as a gene fusion between exon 18 of FGFR3 and exon 6 or exon 14 of TACC3 and agene fusion between exon 19 of FGFR3 and exon 11 of TACC3. In addition, we showed that the FGFR3-TACC3 fusion gene promotes cell proliferation, colony formation, and transforming ability in vitro, whereas the FGFR3-TACC3 K508M mutant or treatment with the FGFR inhibitor PD173074 abrogates these effects, suggesting that FGFR3-TACC3 most likely exerts its effects through activation of FGFR kinase activity. This activation likely leads to the development of NPC. Additionally, FGFR3-TACC3 could trigger activation of the ERK and Akt signaling pathways, whereas FGFR3-TACC3 K508M mutant could not, suggesting that these 2 signaling pathways might be involved in the function of FGFR3-TACC3. Taken together, our data demonstrated the oncogenic role of FGFR3-TACC3 in vitro, indicating that FGFR3-TACC3 may be useful as a diagnostic marker and therapeutic target in cancers.

miR-99a suppresses the metastasis of human non-small cell lung cancer cells by targeting AKT1 signaling pathway

MicroRNAs (miRNAs) play an important role in the development and progression of non-small cell lung cancer (NSCLC). Recently, several studies have shown that miR-99a is downregulated in various cancers, which can affect tumor initiation and maintenance. Herein, we found that miR-99a was downregulated in NSCLC tissues and suppressed tumor metastasis of NSCLC cells. Down-regulation of miR-99a is significantly associated with last-stage and tumor metastasis in NSCLC patients. Further functional experiments found that overexpression of miR-99a inhibit cell proliferation, migration, and invasion of NSCLC cells in vitro and tumor metastasis of NSCLC in vivo. In addition, we also found that AKT1 is directly involved in miR-99a-mediated tumor suppression. Restored the expression of AKT1 partially abolished the suppressive effects miR-99a on proliferation and invasion of NSCLC cells. Collectively, our data suggest that miR-99a plays an important role in the tumorigenesis and metastasis of NSCLC and may serve as a therapeutic target to avoid dissemination of NSCLC cells.

Mechanisms of Invasion in Head and Neck Cancer

CONTEXT

The highly invasive properties demonstrated by head and neck squamous cell carcinoma (HNSCC) are often associated with locoregional recurrence and lymph node metastasis in patients and is a key factor leading to an expected 5-year survival rate of approximately 50% for patients with advanced disease. It is important to understand the features and mediators of HNSCC invasion so that new treatment approaches can be developed.

OBJECTIVES

To provide an overview of the characteristics, mediators, and mechanisms of HNSCC invasion.

DATA SOURCES

A literature review of peer-reviewed articles in PubMed on HNSCC invasion.

CONCLUSIONS

Histologic features of HNSCC tumors can help predict prognosis and influence clinical treatment decisions. Cell surface receptors, signaling pathways, proteases, invadopodia function, epithelial-mesenchymal transition, microRNAs, and tumor microenvironment are all involved in the regulation of the invasive behavior of HNSCC cells. Identifying effective HNSCC invasion inhibitors has the potential to improve outcomes for patients by reducing the rate of spread and increasing responsiveness to chemoradiation.

Circulating microRNAs as novel prognosis biomarkers for head and neck squamous cell carcinoma

Circulating microRNAs (miRNAs) are emerging as promising non-invasive biomarkers for human cancer. Head and neck squamous cell carcinoma (HNSCC) is a prevalent malignancy worldwide, but its overall survival has remained unchanged in the past 3 decades. Biomarkers for evaluating efficacy of cancer therapy are urgently needed. To explore circulating miRNAs as cancer therapy biomarkers, we initially identified that 8 miRNAs were distinctly dysregulated in cancerous tissues compared with adjacent non-cancerous counterparts from 16 patients, using microarray and real-time PCR. Based on this discovery, the comparison study was performed between pre- and 6 months post-operative paired plasma samples on 9 patients. MiR-99a, which was down-regulated in cancerous tissues, was significantly increased in plasma after operation. Meanwhile, oncomiR miR-21 and miR-223 that were up-regulated in cancerous tissues, were significantly reduced in post-operative plasma samples. We firstly report the significant changes of miR-99a in plasma of HNSCC patients after surgery. Furthermore, plasma miR-223 was inversely increased in a patient whose cancer relapsed within 6 months after operation. We conclude that these circulating miRNAs may serve as biomarkers to evaluate the efficacy of therapy and the prognosis of HNSCC.

Tumor suppressor role of miR-133a in gastric cancer by repressing IGF1R

AIM: To investigate the function and mechanism of miR-133a in gastric cancer (GC) and its relationship with clinicopathological characteristics of GC.

METHODS: A total of 105 GC patients who underwent surgical resection as primary treatment were selected for this study. Real-time quantitative reverse transcriptase polymerase chain (qRT-PCR) was used to examine the expression levels of miR-133a in human GC and adjacent non-tumor tissues, as well as in GC cell lines (SGC-7901, BGC-823, MGC-803, and AGS) and a human gastric mucosal epithelial cell line (GES-1). The biological role of miRNA (miR)-133a was assessed in the GC cell lines using MTT, apoptosis, migration and invasion, and colony formation assays, and xenograft tumorigenesis. qRT-PCR and western blot analyses were used to evaluate the potential target gene expression of miR-133a. Pearson’s correlation was calculated to evaluate the correlation between miR-133a and insulin-like growth factor 1 receptor (IGF1R) expression. The regulation of IGF1R by miR-133a was verified using the luciferase reporter assay.

RESULTS: In 80% of the 105 GC patients, the mean expression of miR-133a was significantly downregulated in tumor tissues compared with adjacent normal tissues (1.215 ± 0.1477 vs 3.093 ± 0.4104, P < 0.0001). Downregulation of miR-133a was significantly correlated with the degree of differentiation (P = 0.01), local invasion (P = 0.001) and TNM stage (P = 0.02) in GC patients. Compared with a control construct, forced expression of miR-133a in GC cell lines inhibited proliferation (0.4787 ± 0.0219 vs 0.7050 ± 0.0147, P = 0.0013 in SGC-7901 cells; and 0.5448 ± 0.0085 vs 0.7270 ± 0.0084, P = 0.001 in MGC-803 cells); migration (0.6333 ± 0.0233 vs 1.037 ± 0.0584, P = 0.003 in SGC-7901 cells; 0.6126 ± 0.0311 vs 1.024 ± 0.0456, P = 0.0017 in MGC-803 cells); and invasion (0.613 ± 0.0399 vs 1.033 ± 0.0278, P = 0.0013 in SGC-7901 cells; 0.7433 ± 0.0221 vs 1.017 ± 0.0311, P = 0.002 in MGC-803 cells). It also induced apoptosis (18.19% ± 0.2483% vs 5.887% ± 0.3837%, P < 0.0001 in SGC-7901 cells; 22.69% ± 0.7846% vs 9.347% ± 0.3012%, P < 0.0001 in MGC-803 cells). Furthermore, miR-133a inhibited tumor growth and xenograft tumorigenesis of SGC -7901 cells in vivo. In addition, we identified IGF1R as a regulatory target of miR-133a in GC.

CONCLUSION: This study suggests that miR-133a is downregulated in GC and functions as a tumor suppressor in vitro and in vivo partly by repressing IGF1R.

Elevated Lin28B expression is correlated with lymph node metastasis in oral squamous cell carcinomas

BACKGROUND

Lymph node (LN) metastasis is the most common cause of oral squamous cell carcinoma (OSCC)-related death. Searching the detailed molecular mechanisms involved LN metastasis in OSCC is still an open question.

METHODS

Paired tissue samples from tumor (T) and adjacent non-cancerous matched tissues (NCMT) parts, as well as LN metastatic lesions in patient with OSCC tissues were subjected to quantitative real-time PCR analysis for the expression levels of Lin28B. Arecoline, a major areca nut alkaloid, was to explore whether expression of Lin28B could be changed dose dependent in oral epithelial cells. Control and Lin28B-knockdown arecoline-stimulated oral epithelial cells were subjected to migration/invasion/anchorage-independent growth assay.

RESULTS

Compared with NCMT samples from the same OSCC patient, the expression of Lin28B was increased in all of the tumor samples. A similar upregulation of Lin28B was also observed in LN metastatic when compared with local tumors. Arecoline treatment dose dependently induced Lin28B expression in SG and FaDu cells. Lentiviral-mediated silencing Lin28B expression significantly attenuated arecoline-induced oncogenicity including proliferation, migration, invasiveness, and anchorage-independent growth in SG and FaDu cells.

CONCLUSIONS

Lin28B may be a useful biomarker and novel molecular target for LN metastasis OSCC patients' treatment.

MiR-34a inhibits oral cancer progression partially by repression of interleukin-6-receptor

Previous reports revealed that a significant decrease of miR-34a in oral cancer. But the role of miR-34a in oral cancer needs further research. In the present study, we will investigate the effect of miR-34a on oral cancer cell phenotypes. First, it was verified that miR-34a expression was lower in oral cancer tissues compared with their normal controls, so did the oral cancer cells. Next, it was showed that miR-34a overexpression in oral cancer cells could inhibit cell proliferation, G1 phase arrest, metastasis and epithelial mesenchymal transition. It was predicted that interleukin-6-receptor (IL6R) was a potential target gene of miR-34a by bioinformatics analysis and identified by luciferase assay. It was further showed that miR-34a inhibited oral cancer progression via IL6R. Collectively, our findings suggested that miR-34a may function as a tumor suppressor in oral cancer by targeting IL6R.

Type 2 diabetes mellitus and risk of oral cancer and precancerous lesions: a meta-analysis of observational studies

OBJECTIVE

Associations between type 2 diabetes mellitus (type 2 DM) and risk of oral cancer and precancerous lesions have been reported with controversial findings. We performed a meta-analysis to explore these associations.

METHODS

We identified studies by a literature search of MEDLINE and EMBASE through May 31, 2014, and by searching the reference lists of pertinent articles. Summary relative risk (SRR) with 95% confidence interval (CI) was calculated with a random-effects model. Between- study heterogeneity was assessed using the Cochran's Q and I(2) statistics.

RESULTS

A total of 13 studies (4 case-control and 9 cohort studies) on the association between type 2 DM and oral cancer were included. Overall analysis found that compared with non-diabetic individuals, individuals with type 2 DM had a significantly elevated incidence of oral cancer (SRR=1.15, 95% CI: 1.02-1.29; Pheterogeneity=0.277, I(2)=15.4%; 10 studies). Subgroup analyses found that duration of follow-up (⩾11years) significantly altered this positive association. Type 2 DM was associated with increased oral cancer mortality (SRR=1.41, 95% CI: 1.16-1.72; 4 studies). Meta-analysis of the four case-control studies showed a positive association between type 2 DM and risk of oral precancerous lesions (SRR=1.85, 95%CI: 1.23-2.80; Pheterogeneity=0.038, I(2)=57.5%). No significant public bias was found across these studies.

CONCLUSIONS

These findings of this meta-analysis indicate that compared with non-diabetic individuals, individuals with type 2 DM have an elevated risk of oral cancer and precancerous lesions development.

Regulation of IGF -1 signaling by microRNAs

The insulin-like growth factor 1 (IGF-1) signaling pathway regulates critical biological processes including development, homeostasis, and aging. Dysregulation of this pathway has been implicated in a myriad of diseases such as cancers, neurodegenerative diseases, and metabolic disorders, making the IGF-1 signaling pathway a prime target to develop therapeutic and intervention strategies. Recently, small non-coding RNA molecules in ∼22 nucleotide length, microRNAs (miRNAs), have emerged as a new regulator of biological processes in virtually all organ systems and increasing studies are linking altered miRNA function to disease mechanisms. A miRNA binds to 3'UTRs of multiple target genes and coordinately downregulates their expression, thereby exerting a profound influence on gene regulatory networks. Here we review the components of the IGF-1 signaling pathway that are known targets of miRNA regulation, and highlight recent studies that suggest therapeutic potential of these miRNAs against various diseases.

Downregulated miR329 and miR410 promote the proliferation and invasion of oral squamous cell carcinoma by targeting Wnt-7b

microRNA (miRNA) dysregulation contributes widely to human cancer but has not been fully assessed in oral cancers. In this study, we conducted a global microarray analysis of miRNA expression in 40 pairs of betel quid-associated oral squamous cell carcinoma (OSCC) specimens and their matched nontumorous epithelial counterparts. Eighty-four miRNAs were differentially expressed in the OSCC specimens compared with the matched tissue. Among these downregulated miRNAs, 19 miRNAs were found and mapped to the chromosome 14q32.2 miRNA cluster region, which resides within a parentally imprinted region designated as Dlk-Dio3 and known to be important in development and growth. Bioinformatic analysis predicted two miRNAs from the cluster region, miR329 and miR410, which could potentially target Wnt-7b, an activator of the Wnt-β-catenin pathway, thereby attenuating the Wnt-β-catenin signaling pathway in OSCC. Stable ectopic expression of Wnt-7b in OSCC cells overexpressing miR329 or miR410 restored proliferation and invasion capabilities abolished by these miRNA. Combining a demethylation agent and a histone deacetylase inhibitor was sufficient to reexpress miR329, miR410, and Meg3, consistent with epigenetic regulation of these miRNA in human OSCC. Specifically, arecoline, a major betel nut alkaloid, reduced miR329, miR410, and Meg3 gene expression. Overall, our results provide novel molecular insights into how betel quid contributes to oral carcinogenesis through epigenetic silencing of tumor-suppressor miRNA that targets Wnt-β-catenin signaling.

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.

MiR-195 inhibits the growth and metastasis of NSCLC cells by targeting IGF1R

MicroRNAs (miRNAs) are small, non-coding RNAs which act as oncogenes or tumor suppressors in multiple human cancers. Accumulating evidence reveals that aberrant expression of miRNAs contributes to the development and progression of non-small cell lung cancer (NSCLC). Here, we identified miR-195 as a tumor suppressor in NSCLC cells, whose expression level was dramatically decreased in both NSCLC tissues and cell lines. Ectopic expression of miR-195 suppressed NSCLC cell proliferation and metastasis-related traits in vitro. Insulin-like growth factor 1 receptor (IGF1R) was identified as a direct target of miR-195 in NSCLC cells. Furthermore, restoration of IGF1R remarkably attenuated the tumor suppressive effects of miR-195 on NSCLC cells. Our data suggest that miR-195 may be involved in the carcinogenesis of NSCLC partially by targeting IGF1R.