HMGA1 and HMGA2 expression and comparative analyses of HMGA2, Lin28 and let-7 miRNAs in oral squamous cell carcinoma

A review on microRNA detection and expression studies in dogs

MicroRNAs (miRNAs) are small non-coding RNAs that function by post-transcriptional regulation of gene expression. Their stability and abundance in tissue and body fluids makes them promising potential tools for both the diagnosis and prognosis of diseases and attractive therapeutic targets in humans and dogs. Studies of miRNA expression in normal and disease processes in dogs are scarce compared to studies published on miRNA expression in human disease. In this literature review, we identified 461 peer-reviewed papers from database searches using the terms "canine," "dog," "miRNA," and "microRNA"; we screened 244 for inclusion criteria and then included a total of 148 original research peer-reviewed publications relating to specific miRNA expression in canine samples. We found an overlap of miRNA expression changes between the four groups evaluated (normal processes, non-infectious and non-inflammatory conditions, infectious and/or inflammatory conditions, and neoplasia) in 39 miRNAs, 83 miRNAs in three of the four groups, 110 miRNAs in two of the three groups, where 158 miRNAs have only been reported in one of the groups. Additionally, the mechanism of action of these overlapping miRNAs varies depending on the disease process, elucidating a need for characterization of the mechanism of action of each miRNA in each disease process being evaluated. Herein we also draw attention to the lack of standardization of miRNA evaluation, consistency within a single evaluation method, and the need for standardized methods for a direct comparison.

Let-7, Lin28 and Hmga2 Expression in Ciliary Epithelium and Retinal Progenitor Cells

Purpose

Ciliary epithelium (CE) of adult mammalian eyes contains quiescent retinal progenitor/stem cells that generate neurospheres in vitro and differentiate into retinal neurons. This ability doesn't evolve efficiently probably because of regulatory mechanisms, such as microRNAs (miRNAs) that control pluripotent, progenitor, and differentiation genes. Here we investigate the presence of Let-7 miRNAs and its regulator and target, Lin28 and Hmga2, in CE cells from neurospheres, newborns, and adult tissues.

Methods

Newborn and adult rats CE cells were dissected into pigmented and nonpigmented epithelium (PE and NPE). Newborn PE cells were cultured with growth factors to form neurospheres and we analyzed Let-7, Lin28a, and Hmga2 expression. During the neurospheres formation, we added chemically modified single-stranded oligonucleotides designed to bind and inhibit or mimic endogenous mature Let-7b and Let-7c. After seven days in culture, we analyzed neurospheres size, number and expression of Let-7, Lin28, and Hmga2.

Results

Let-7 miRNAs were expressed at low rates in newborn CE cells with significant increase in adult tissues, with higher levels on NPE cells, that does not present the stem cells reprogramming ability. The Lin28a and Hmga2 protein and transcripts were more expressed in newborns than adults cells, opposed to Let-7. Neurospheres presented higher Lin28 and Hmga2 expression than newborn and adult, but similar Let-7 than newborns. Let-7b inhibitor upregulated Hmga2 expression, whereas Let-7c mimics upregulated Lin28 and downregulated Hmga2.

Conclusions

This study shows the dynamic of Lin28-Let-7-Hmga regulatory axis in CE cells. These components may develop different roles during neurospheres formation and postnatal CE cells.

Molecular mechanism of targeted inhibition of HMGA2 via miRNAlet-7a in proliferation and metastasis of laryngeal squamous cell carcinoma

MiRNAlet-7a is associated with the tumorigenesis of laryngeal squamous cell carcinoma (LSCC). Our study was designed to infer whether let-7a targets high-mobility AT-hook 2 (HMGA2) and suppresses laryngeal carcinoma cell proliferation, invasion, and migration. The expression levels of let-7a and HMGA2 were measured in 30 LSCC clinical specimens by qRT-PCR and their correlation was analyzed. Cell model and mice xenograft model with or without let-7a overexpression were constructed to evaluate the effects of let-7a on LSCC. Moreover, luciferase assay was performed to reveal the interaction between let-7a and HMGA2, which was further verified in xenograft. Let-7a was significantly down-regulated and HMGA2 was up-regulated in LSCC tissues compared with normal tissues (P<0.05), both of which were significantly correlated with TNM stage and lymph node metastases of LSCC patients (P<0.05). We also observed a negative correlation between let-7a and HMGA2 expression in LSCC samples (r = -0.642, P<0.05). In vitro and in vivo experiments demonstrated that let-7a overexpression could inhibit cell proliferation and tumor growth of LSCC and simultaneously down-regulate the expression of HMGA2. Moreover, the regulation of HMGA2 by let-7a was also proved by luciferase assay. Our results revealed that let-7a promotes development and progression of LSCC through inhibiting the expression of HMGA2. Therefore, let-7a may thus be a potential diagnostic biomarker and therapeutic target for treating LSCC.

MYC-regulated pseudogene HMGA1P6 promotes ovarian cancer malignancy via augmenting the oncogenic HMGA1/2

Pseudogenes have long been considered as nonfunctional genomic sequences. Recent studies have shown that they can potentially regulate the expression of protein-coding genes and are dysregulated in diseases including cancer. However, the potential roles of pseudogenes in ovarian cancer have not been well studied. Here we characterized the pseudogene expression profile in HGSOC (high-grade serous ovarian carcinoma) by microarray. We identified 577 dysregulated pseudogenes and most of them were up-regulated (538 of 577). HMGA1P6 (High mobility group AT-hook 1 pseudogene 6) was one of the overexpressed pseudogenes and its expression was inversely correlated with patient survival. Mechanistically, HMGA1P6 promoted ovarian cancer cell malignancy by acting as a ceRNA (competitive endogenous RNA) that led to enhanced HMGA1 and HMGA2 expression. Importantly, HMGA1P6 was transcriptionally activated by oncogene MYC in ovarian cancer. Our findings reveal that MYC may contribute to oncogenesis through transcriptional regulation of pseudogene HMGA1P6 in ovarian cancer.

The Prominent Role of HMGA Proteins in the Early Management of Gastrointestinal Cancers

GI tumors represent a heterogeneous group of neoplasms concerning their natural history and molecular alterations harbored. Nevertheless, these tumors share very high incidence and mortality rates worldwide and patients' poor prognosis. Therefore, the identification of specific biomarkers could increase the development of personalized medicine, in order to improve GI cancer management. In this sense, HMGA family members (HMGA1 and HMGA2) comprise an important group of genes involved in the genesis and progression of malignant tumors. Additionally, it has also been reported that HMGA1 and HMGA2 display an important role in the detection and progression of GI tumors. In this way, HMGA family members could be used as reliable biomarkers able to efficiently track not only the tumor per se but also the main risk conditions related with their development of GI cancers in the future. Finally, it shall be a promising option to revert the current scenario, once HMGA genes and proteins could represent a convergence point in the complex landscape of GI tumors.

LIN28: A cancer stem cell promoter for immunotherapy in head and neck squamous cell carcinoma

Lin28, a highly conserved RNA-binding protein, plays an important role in differentiation, metabolism, proliferation, pluripotency, and tumourigenicity. Lin28 overexpression promotes tumour-cell proliferation and metastasis in various human cancers, including head and neck cancer. Multiple studies demonstrate that Lin28 critically contributes to anti-tumour immunity and production of cancer stem cells in head and neck squamous cell carcinoma (HNSCC). Thus, Lin28 has potential application in HNSCC treatment.

HMGA2 Contributes to Distant Metastasis and Poor Prognosis by Promoting Angiogenesis in Oral Squamous Cell Carcinoma

The highly malignant phenotype of oral squamous cell carcinoma (OSCC), including the presence of nodal and distant metastasis, reduces patient survival. High-mobility group A protein 2 (HMGA2) is a non-histone chromatin factor that is involved in advanced malignant phenotypes and poor prognosis in several human cancers. However, its biological role in OSCC remains to be elucidated. The purpose of this study was to determine the clinical significance and role of HMGA2 in the malignant potential of OSCC. We first investigated the expression pattern of HMGA2 and its clinical relevance in 110 OSCC specimens using immunohistochemical staining. In addition, we examined the effects HMGA2 on the regulation of vascular endothelial growth factor (VEGF)-A, VEGF-C, and fibroblast growth factor (FGF)-2, which are related to angiogenesis, in vitro. High expression of HMGA2 was significantly correlated with distant metastasis and poor prognosis. Further, HMGA2 depletion in OSCC cells reduced the expression of angiogenesis genes. In OSCC tissues with high HMGA2 expression, angiogenesis genes were increased and a high proportion of blood vessels was observed. These findings suggest that HMGA2 plays a significant role in the regulation of angiogenesis and might be a potential biomarker to predict distant metastasis and prognosis in OSCC.

Non-murine models to investigate tumor-immune interactions in head and neck cancer

The immune response has important roles in the biology of solid tumors, including oncogenesis, tumor growth, invasion and metastasis, and response to treatment. Improved understanding of tumor-immune system interactions has provided promising therapeutic options that are based on the rescue and enhancement of the anti-tumoral host response. Immune-based treatments have been approved for clinical use in various types of cancer, including head and neck cancer (HNC); other strategies involving combination therapies are currently in development. These novel therapies were developed based on knowledge derived from in vitro, in silico, and in vivo pre-clinical studies. However, clinical trials seldom replicate the efficacy observed in pre-clinical animal studies. This lack of correlation between pre-clinical studies and clinical trials may be related to limitations of the models used; which highlights the relevance of considering immune-related aspects of different pre-clinical models. Murine models are the most frequently used pre-clinical models of HNC and are discussed elsewhere. Non-murine models have characteristics that offer unique opportunities for the study of HNC etiology, therapeutic strategies, and tumor-immune system interactions. The current review focuses on immune-related aspects of non-murine models, including dog, cat, pig, zebrafish, and frog, that could be used to investigate tumor-immune interactions in HNC.

MicroRNA let‑7d‑5p rescues ovarian cancer cell apoptosis and restores chemosensitivity by regulating the p53 signaling pathway via HMGA1

Ovarian cancer (OC) is the gynecological malignancy type with the highest mortality rate in females. The regulatory effect of microRNAs (miRs) on their target genes serves a key role in tumor development. Therefore, in the present study, whether miR let‑7d‑5p targeting high mobility group A1 (HMGA1) regulated biological characteristics and chemosensitivity of OC cells by mediating the p53 signaling pathway was investigated. The let‑7d‑5p level was detected in OC tissues and adjacent normal tissues, followed by detection in OC cell lines SKOV3, A2780, OVCAR‑3 and CaOV3, and human normal ovarian epithelial cell line (IOSE‑80), in order to select the OC cell line for the following experiments. Subsequently, OC cells were treated with the let‑7d‑5p mimic, siHMGA1 and Tenovin‑1. The targeting association between let‑7d‑5p and HMGA1 was then examined, and the OC cell viability, migration, cycle and apoptosis were evaluated. Subsequently, the chemosensitivity of OC cells to cisplatin was verified. Finally, expression levels of let‑7d‑5p, HMGA1, p21, B‑cell lymphoma‑2 (Bcl‑2)‑associated X (Bax), p27, p53 wild‑type (p53wt), p53 mutated (p53mut), proliferating cell nuclear antigen (PCNA), cyclin‑dependent kinase 2 (CDK2), matrix metallopeptidase (MMP)2, MMP9 and Bcl‑2 were determined. As demonstrated in the results, let‑7d‑5p expression was low in OC tissues and had an increased reduction in the OVCAR‑3 cell line. HMGA1 was confirmed as a target of let‑7d‑5p, and its expression was also silenced by let‑7d‑5p. let‑7d‑5p repressed OC cell viability, migration, cell cycle progression and apoptosis, while it promoted the chemosensitivity of OC cells to cisplatin by targeting HMGA1. The expression of let‑7d‑5p, p21, Bax, p27 and p53wt was increased, while that of HMGA1, p53mut, PCNA, CDK2, MMP2, MMP9 and Bcl‑2 was reduced following cell transfection. The results in the present study provided evidence that let‑7d‑5p may suppress proliferation, and facilitate apoptosis and cisplatin chemosensitivity of OC cells by silencing HMGA1 via the p53 signaling pathway.

The expressions of HMGA2 and Thy1 in extrahepatic cholangiocarcinoma and their clinicopathological significances

AIMS

Extrahepatic cholangiocarcinoma is a malignant tumor and poor prognosis with intrinsic resistance to cytotoxic agents. The molecular mechanism associated with high malignancy and resistance to chemotherapy and radiotherapy has not been fully elucidated. This study aims to investigate the clinicopathological significances of HMGA2 and Thy1 expression in extrahepatic cholangiocarcinoma.

METHODS

The expressions of HMGA2 and Thy1 in 100 extrahepatic cholangiocarcinoma, 30 peritumoral tissues, 10 adenoma and 15 normal biliary tract tissues were assayed using EnVision immunohistochemistry.

RESULTS

The HMGA2 and Thy1 proteins were overexpression in extrahepatic cholangiocarcinoma compared to peritumoral tissues, adenoma, and normal biliary tract tissues (P < 0.05 or P < 0.01). Adenoma and pericancerous tissues with positive HMGA2 or/and Thy1 protein expression exhibited atypical hyperplasia. The positive correlation was found between the expression of HMGA2 and Thy1 in extrahepatic cholangiocarcinoma (P < 0.01). The positive rates of HMGA2 and Thy1 expression were significantly higher in cases with poor differentiation, lymph node metastasis, invasion, and TNM stage III or IV and no resection (biopsy only) (P < 0.05 or P < 0.01). Kaplan-Meier survival analysis showed that the survival of extrahepatic cholangiocarcinoma patients with positive HMGA2 and/or Thy1 expression is significantly shorter than patients with negative HMGA2 and/or Thy1 expression (P = 0.000). Cox multivariate analysis revealed that positive HMGA2 and/or Thy1 expressions were independently poor prognosis factors in extrahepatic cholangiocarcinoma patients. We calculated the AUC for HMGA2 (AUC = 0.610, 95%CI: 0.519-0.702), or Thy1 (AUC = 0.675, 95%CI: 0.588-0.762), respectively.

CONCLUSIONS

The present study indicated that positive HMGA2 and Thy1 expression are closely associated with the pathogenesis, clinical, pathological and biological behaviors, and poor prognosis in patients with extrahepatic cholangiocarcinoma.

Proteomic analysis of canine oral tumor tissues using MALDI-TOF mass spectrometry and in-gel digestion coupled with mass spectrometry (GeLC MS/MS) approaches

Oral tumors, including highly invasive and metastatic oral melanoma (OM), non-tonsillar oral squamous cell carcinoma (OSCC) and benign tumors (BN), are common neoplasms in dogs. Although these tumors behave differently, limited data of their protein expression profiles have been exhibited, particularly at the proteome level. The present study aimed to i.) characterize peptide-mass fingerprints (PMFs) and identify potential protein candidates of OM, OSCC, BN and normal control subjects, using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and liquid chromatography tandem mass spectrometry (LC-MS/MS), ii.) identify potential protein candidates associated with the diseases, using in-gel digestion coupled with mass spectrometric analysis (GeLC-MS/MS) and iii.) search for relationships between chemotherapy drugs and disease-perturbed proteins. A distinct cluster of each sample group and unique PMFs with identified protein candidates were revealed. The unique peptide fragment at 2,274 Da of sacsin molecular chaperone (SACS) was observed in early-stage OM whereas the fragment at 1,958 Da of sodium voltage-gated channel alpha subunit 10 (SCN10A) was presented in early- and late-stage OM. The peptide mass at 2,316 Da of Notch1 appeared in early-stage OM and benign oral tumors while the peptide mass at 2,505 Da of glutamate ionotropic receptor N-methyl-D-aspartate type subunit 3A (GRIN3A) was identified in all groups. Markedly expressed proteins from GeLC-MS/MS included Jumonji domain containing 1C (JMJD1C) in benign tumors, inversin (INVS) and rho guanine nucleotide exchange factor 28 (ARHGEF28) in OM, BTB domain-containing 16 (BTBD16) in OSCC, and protein tyrosine phosphatase non-receptor type 1 (PTPN1), BRCA2, DNA repair associated (BRCA2), WW domain binding protein 2 (WBP2), purinergic receptor P2Y1 and proteasome activator subunit 4 (PSME4) in all cancerous groups. The network connections between these proteins and chemotherapy drugs, cisplatin and doxorubicin, were also demonstrated. In conclusion, this study unveiled the unique PMFs and novel candidate protein markers of canine oral tumors.

Expressions of miR-30c and let-7a are inversely correlated with HMGA2 expression in squamous cell carcinoma of the vulva

Malignant tumors of the vulva, most of them squamous cell carcinomas, account for only 5% of cancers of the female genital tract. Though little is known about the genetic features of these tumors, the Fragile Histidine Triad (FHIT) and High Mobility Group AT-hook 2 (HMGA2) genes were found deregulated. We wanted to gain more knowledge about the expression of HMGA2-related miRNAs such as miR-30c and let-7a, and whether a correlation exists between the expression of FHIT and HMGA2, in this tumor type. An inverse correlation was found in-as-much as HMGA2 was highly expressed (mean fold change 8.8) whereas miR30c and let-7a were both downregulated (mean fold change -3.9 and -2.3, respectively). The consistent overexpression of HMGA2 found in all tumors adds to the likelihood that this gene is of importance in SCC pathogenesis. Moreover, we came to the conclusion that miRNAs may be the cause of the deregulation of HMGA2. Our results also show that SCC of the vulva presents a characteristic molecular pattern with FHIT being downregulated whereas HMGA2 is upregulated.

HMGA2 overexpression plays a critical role in the progression of esophageal squamous carcinoma

Esophageal Squamous Cell Carcinoma (ESCC) is the most common esophageal tumor worldwide. However, there is still a lack of deeper knowledge about biological alterations involved in ESCC development. High Mobility Group A (HMGA) protein family has been related with poor outcome and malignant cell transformation in several tumor types. In this way, the aim of this study was to analyze the expression of HMGA1 and HMGA2 expression in ESCC and their role in crucial cellular features. We evaluated HMGA1 and HMGA2 mRNA expression in 52 paired ESCC and normal surrounding tissue samples by qRT-PCR. Here, we show that HMGA2, but not HMGA1, is overexpressed in ESCC samples. This result was further confirmed by the immunohistochemical analysis. Indeed, accordingly to mRNA expression data, HMGA2, but not HMGA1, was overexpressed in approximately 90% of ESCC samples, while it was barely expressed in the respective control. Conversely, HMGA1, but not HMGA2, was overexpressed in esophageal adenocarcinoma samples. Interestingly, HMGA2 abrogation attenuated the malignant phenotype of two ESCC cell lines, suggesting that HMGA2 overexpression is involved in ESCC progression.

MiR-98 inhibits malignant progression via targeting MTDH in squamous cell carcinoma of the head and neck

PURPOSE

MicroRNAs function through regulating specific target mRNA expression and then participate in the development and progression of diverse human cancers. MiR-98 shows aberrant expression and dysfunction in tumors. However, its clinical significance and exact role in squamous cell carcinoma of the head and neck (SCCHN) remain elusive.

METHODS

MiR-98 expression was examined by qRT-PCR and correlated with clinicopathological variables and prognosis in SCCHN patients. Effects of miR-98 on epithelial-mesenchymal transition (EMT) and the malignant phenotypes of SCCHN were studied. Finally, the role of target gene metadherin (MTDH) in miR-98 mediated effects were assayed.

RESULTS

Our results demonstrated that miR-98, as an endogenous inhibitor of MTDH via directly binding to its 3'-untranslated region (UTR) region, decreased significantly in SCCHN tissues. Decreased miR-98 expression was negatively correlated with T classification, clinical stage, lymph node metastasis and a shorter survival status in SCCHN patients. Loss-of-function and gain-of-function analyses confirmed that miR-98 inhibited cell proliferation, migration and invasion of SCCHN cells in vitro. Moreover, miR-98 repression led to increased MTDH expression and induced EMT alteration. Importantly, ectopic expression of MTDH partially reversed the effects caused by miR-98 overexpression.

CONCLUSIONS

Our study identifies that miR-98 serves as a suppressor in SCCHN progression via targeting oncogene MTDH.

Curcumin Inhibits LIN-28A through the Activation of miRNA-98 in the Lung Cancer Cell Line A549

Metastasis is common in lung cancer and is associated with poor clinical outcomes and increased mortality. Curcumin is a natural anti-cancer agent that inhibits the metastasis of various cancers by modulating the expression of micro (mi) RNAs such as miR-98, which acts as a tumor suppressor. This study investigated the effect of curcumin on miR-98 expression and in vitro cell line growth and invasiveness in lung cancer. Curcumin treatment enhanced the expression of miR-98 and reduced that of the miR-98 target gene LIN28A as well as matrix metalloproteinase (MMP) 2 and MMP9 in vitro and in vivo. MiR-98 overexpression suppressed lung cancer cell migration and invasion by inhibiting LIN28A-induced MMP2 and MMP9 expression. Meanwhile, LIN28A level was downregulated by overexpression of miR-98 mimic. Induction of miR-98 by curcumin treatment suppressed MMP2 and MMP9 by targeting LIN28A. These findings provide insight into the mechanisms by which curcumin suppresses lung cancer cell line growth in vitro and in vivo and invasiveness in vitro.

The LIN28/let-7 Pathway in Cancer

Among all tumor suppressor microRNAs, reduced let-7 expression occurs most frequently in cancer and typically correlates with poor prognosis. Activation of either LIN28A or LIN28B, two highly related RNA binding proteins (RBPs) and proto-oncogenes, is responsible for the global post-transcriptional downregulation of the let-7 microRNA family observed in many cancers. Specifically, LIN28A binds the terminal loop of precursor let-7 and recruits the Terminal Uridylyl Transferase (TUTase) ZCCHC11 that polyuridylates pre-let-7, thereby blocking microRNA biogenesis and tumor suppressor function. For LIN28B, the precise mechanism responsible for let-7 inhibition remains controversial. Functionally, the decrease in let-7 microRNAs leads to overexpression of their oncogenic targets such as MYC, RAS, HMGA2, BLIMP1, among others. Furthermore, mouse models demonstrate that ectopic LIN28 expression is sufficient to drive and/or accelerate tumorigenesis via a let-7 dependent mechanism. In this review, the LIN28/let-7 pathway is discussed, emphasizing its role in tumorigenesis, cancer stem cell biology, metabolomics, metastasis, and resistance to ionizing radiation and several chemotherapies. Also, emerging evidence will be presented suggesting that molecular targeting of this pathway may provide therapeutic benefit in cancer.

Let-7 inhibits self-renewal of hepatocellular cancer stem-like cells through regulating the epithelial-mesenchymal transition and the Wnt signaling pathway

Background

Tumor suppressive let-7 miRNAs are universally down-regulated in human hepatocellular carcinoma (HCC) versus normal tissues; however, the roles and related molecular mechanisms of let-7 in HCC stem cells are poorly understood.

Methods

We examined the inhibitory effect of let-7 miRNAs on the proliferation of MHCC97-H and HCCLM3 hepatic cancer cells by using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, which was further confirmed by apoptosis and cell cycle studies. The sphere-forming assay was used to study the effects of let-7a on stem like cells. Through western blot, immunofluorescence and the luciferase-reporter assay, we explored the activity of epithelial-mesenchymal transition (EMT) signaling factors in HCC cells. qRT-PCR was applied to detect miRNA expression levels in clinical tissues.

Results

Let-7a effectively repressed cell proliferation and viability, and in stem-like cells, also let-7a decreased the efficiency of sphere formation.in stem-like cells. The suppression of EMT signaling factors in HCC cells contributed to let-7’s induced tumor viability repression and Wnt activation repression. Besides, Wnt1 is critical and essential for let-7a functions, and the rescue with recombinant Wnt1 agent abolished the suppressive roles of let-7a on hepatospheres. In clinical HCC and normal tissues, let-7a expression was inversely correlated with Wnt1 expression.

Conclusions

Let-7 miRNAs, especially let-7a, will be a promising therapeutic strategy in the treatment of HCC through eliminating HCC stem cells, which could be achieved by their inhibitory effect on the Wnt signaling pathway.

MiR-4500 is epigenetically downregulated in colorectal cancer and functions as a novel tumor suppressor by regulating HMGA2

This study aimed to understand the exact function and potential mechanism of miR-4500 in colorectal cancer (CRC). In this study, the expression of miR-4500 was decreased in both CRC cells and tissues, and downregulated miR-4500 indicated advanced tumor stage and poor survival. By bisulfite sequencing analysis, we found that the CpG island in the promoter region of miR-4500 was hypermethylated in CRC cells and tissues compared with normal control cells and non-tumor tissues, respectively. Functionally, gain- and loss-of-function analyses indicated the tumor suppressor role of miR-4500: it suppressed cell proliferation, cell cycle progression, migration, and invasion. Predictive algorithms and experimental analyses identified HMGA2 as a direct target of miR-4500. Reintroducing HMGA2 impaired the inhibitory effects of miR-4500 on cell growth and motility. Clinically, higher HMGA2 protein expression in CRC tissues was associated with advanced tumor stage and poor survival. An inverse correlation was found between miR-4500 levels and HMGA2 protein expression. Taken together, this study provides the first evidence that miR-4500 functions as a novel tumor suppressor in the miR-4500/HMGA2 axis in colorectal carcinogenesis, and restoring miR-4500 expression might represent a promising therapeutic strategy for CRC.

Expression of stem cell-regulating miRNAs in oral cavity and oropharynx squamous cell carcinoma

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common tumor worldwide and is histologically heterogeneous. Studies have demonstrated the presence of stem cell markers in HNSCC, and microRNAs (miRNAs) have emerged as powerful regulators of differentiation, controlling the self-renewal of stem cells. miRNAs are non-coding RNA molecules that regulate gene expression post-transcriptionally. Many miRNAs have been described as regulators of stem cells in different types of cancer.

METHODS

We have analyzed the expression of let-7a, miR-34, miR-125b, miR-138, miR-145, miR-183, miR-200b, miR-203, and miR-205 by real-time RT-PCR (qPCR), in 35 oral cavity and oropharynx squamous cell carcinoma (SCC) samples and 10 non-neoplastic oral mucosa controls, to determine possible associations between the expression of these miRNAs and clinical and pathological features of these tumors.

RESULTS

We observed downregulation of miR-200b and miR-203 in 60.0% and 71.4% of the samples, respectively. Upregulation of miR-138 and miR-183 was observed in 50.0% of the samples. Downregulation of let-7a was associated with perineural invasion. Upregulation of miR-138, miRNA-145, and miR-205 was associated with advanced tumor stages, vascular invasion, and lymph node metastasis, respectively.

CONCLUSIONS

Our study provides evidence of the expression of miRNAs associated with stem cell regulation in oral cavity and oropharynx SCC and the association of these miRNAs with clinical and pathological features of these tumors.

The pluripotency factor LIN28B is involved in oral carcinogenesis and associates with tumor aggressiveness and unfavorable prognosis

Objective

LIN28B is a conserved RNA-binding protein critically involved in development, cellular metabolism and tumorigenesis. It is frequently overexpressed in human cancers and correlates with tumor aggressiveness as well as unfavorable prognosis. However, the expression pattern and oncogenic roles of LIN28B during oral squamous cell carcinoma (OSCC) development and progression has not been well established yet. Here, we sought to determine the expression of LIN28B and its clinical significance using chemical-induced OSCC animal model, cell lines and primary specimens.

Method

The OSCC animal model was induced using 7,12-dimethyl-1,2-bezan-tracene (DMBA) painting in the hamster buccal pouch. Buccal lesions from animals were obtained from different time points and subjected to routine histological analyses and immunohistochemical staining of LIN28B. The mRNA, protein abundance and subcellular localization of LIN28B was determined in a panel of OSCC cell lines by real-time RT-PCR, western blot and immunofluorescence. The expression levels of LIN28B in human primary OSCC samples were further evaluated by immunohistochemical staining. Moreover, the relationship between LIN28B and several clinicopathological parameters as well as patients’ prognosis were also assessed.

Results

Our results revealed that negative or low LIN28B expression was commonly observed in normal epithelial, whereas more LIN28B abundance was identified in epithelial dysplasia and invasive SCC in the DMBA-induced OSCC animal model. Overexpression of LIN28B was identified in a major fraction of OSCC samples(39/58) and significantly associated with tumor size (P = 0.049) and advanced clinical stages (P = 0.0286). Patients with increased LIN28B had markedly reduced overall survival as compared to those with low LIN28B. Multivariate survival analyses further indicated that LIN28B abundance served as an independent prognostic factor for patients’ overall survival.

Conclusions

Our findings reveal that LIN28B is critically involved in OSCC initiation and progression and aberrantly overexpressed in human OSCC. It might represent a novel diagnostic and prognostic biomarker for oral cancer.

Genome-wide haplotype association analysis identifies SERPINB9, SERPINE2, GAK, and HSP90B1 as novel risk genes for oral squamous cell carcinoma

The oral squamous cell carcinoma (OSCC) is one of the most common malignant epithelial neoplasms and considered to be caused by the genetic damage. In addition, smoking habit and excessive alcohol consumption have been estimated to be the main risk factors. Although the association between OSCC and genetic susceptibility loci has been observed in many different populations, most of these studies simply focused on the single nucleotide polymorphism. Therefore, we made a contrast analysis between the 112 OSCC patients from the GEO database and 245 normal samples from the HapMap project. First, we performed a genome-wide haplotype association study by comparing the frequency of the haplotypes in the case-control experiment. Then, we mapped the haplotypes to the corresponding genes, screened the risk genes according to significant haplotypes (P < 1E-04), and prioritized the OSCC genes based on their similarity to the known OSCC susceptibility genes. We filtered four OSCC genes including SERPINB9, SERPINE2, GAK, and HSP90B1 through the gene global prioritization score (P < 0.005). SERPINB9 ranked first in the candidate gene list and contained a significant haplotype TAGGA (P value = 3.12E-11). The second risk gene was SERPINE2 with the haplotype GGGCCCTTT, which was closely similar to the SERPINB9.

Circulating small non-coding RNA signature in head and neck squamous cell carcinoma

The Head and Neck Squamous Cell Carcinoma (HNSCC) is the sixth most common human cancer, causing 350,000 individuals die worldwide each year. The overall prognosis in HNSCC patients has not significantly changed for the last decade. Complete understanding of the molecular mechanisms in HNSCC carcinogenesis could allow an earlier diagnosis and the use of more specific and effective therapies. In the present study we used deep sequencing to characterize small non-coding RNAs (sncRNAs) in serum from HNSCC patients and healthy donors. We identified, for the first time, a multi-marker signature of 3 major classes of circulating sncRNAs in HNSCC, revealing the presence of circulating novel and known miRNAs, and tRNA- and YRNA-derived small RNAs that were significantly deregulated in the sera of HNSCC patients compared to healthy controls. By implementing a triple-filtering approach we identified a subset of highly biologically relevant miRNA-mRNA interactions and we demonstrated that the same genes/pathways affected by somatic mutations in cancer are affected by changes in the abundance of miRNAs. Therefore, one important conclusion from our work is that during cancer development, there seems to be a convergence of oncogenic processes driven by somatic mutations and/or miRNA regulation affecting key cellular pathways.

Integrated network analysis and logistic regression modeling identify stage-specific genes in Oral Squamous Cell Carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) is associated with substantial mortality and morbidity but, OSCC can be difficult to detect at its earliest stage due to its molecular complexity and clinical behavior. Therefore, identification of key gene signatures at an early stage will be highly helpful.

METHODS

The aim of this study was to identify key genes associated with progression of OSCC stages. Gene expression profiles were classified into cancer stage-related modules, i.e., groups of genes that are significantly related to a clinical stage. For prioritizing the candidate genes, analysis was further restricted to genes with high connectivity and a significant association with a stage. To assess predictive power of these genes, a classification model was also developed and tested by 5-fold cross validation and on an independent dataset.

RESULTS

The identified genes were enriched for significant processes and functional pathways, and various genes were found to be directly implicated in OSCC. Forward and stepwise, multivariate logistic regression analyses identified 13 key genes whose expression discriminated early- and late-stage OSCC with predictive accuracy (area under curve; AUC) of ~0.81 in a 5-fold cross-validation strategy.

CONCLUSIONS

The proposed network-driven integrative analytical approach can identify multiple genes significantly related to an OSCC stage; the classification model that is developed with these genes may help to distinguish cancer stages. The proposed genes and model hold promise for monitoring of OSCC stage progression, and our findings may facilitate cancer detection at an earlier stage, resulting in improved treatment outcomes.