Suppression of local invasion of ameloblastoma by inhibition of matrix metalloproteinase-2 in vitro

Characterization of tumors of jaw: Additive value of contrast enhancement and dual-energy computed tomography

BACKGROUND

Currently, the differentiation of jaw tumors is mainly based on the lesion's morphology rather than the enhancement characteristics, which are important in the differentiation of neoplasms across the body. There is a paucity of literature on the enhancement characteristics of jaw tumors. This is mainly because, even though computed tomography (CT) is used to evaluate these lesions, they are often imaged without intravenous contrast. This study hypothesised that the enhancement characteristics of the solid component of jaw tumors can aid in the differentiation of these lesions in addition to their morphology by dual-energy CT, therefore improving the ability to differentiate between various pathologies.

AIM

To evaluate the role of contrast enhancement and dual-energy quantitative parameters in CT in the differentiation of jaw tumors.

METHODS

Fifty-seven patients with jaw tumors underwent contrast-enhanced dual-energy CT. Morphological analysis of the tumor, including the enhancing solid component, was done, followed by quantitative analysis of iodine concentration (IC), water concentration (WC), HU, and normalized IC. The study population was divided into four subgroups based on histopathological analysis-central giant cell granuloma (CGCG), ameloblastoma, odontogenic keratocyst (OKC), and other jaw tumors. A one-way ANOVA test for parametric variables and the Kruskal-Wallis test for non-parametric variables were used. If significant differences were found, a series of independent t-tests or Mann-Whitney U tests were used.

RESULTS

Ameloblastoma was the most common pathology (n = 20), followed by CGCG (n = 11) and OKC. CGCG showed a higher mean concentration of all quantitative parameters than ameloblastomas (P < 0.05). An IC threshold of 31.35 × 100 μg/cm3 had the maximum sensitivity (81.8%) and specificity (65%). Between ameloblastomas and OKC, the former showed a higher mean concentration of all quantitative parameters (P < 0.001), however when comparing unilocular ameloblastomas with OKCs, the latter showed significantly higher WC. Also, ameloblastoma had a higher IC and lower WC compared to "other jaw tumors" group.

CONCLUSION

Enhancement characteristics of solid components combined with dual-energy parameters offer a more precise way to differentiate between jaw tumors.

Molecular biological findings of ameloblastoma

Ameloblastoma is benign odontogenic tumours that mainly occur in the jawbone. This tumour induces aggressive invasion into the surrounding bone and has a high recurrence rate after surgery. Therefore, mandibular resection is performed in many patients with this tumour, causing aesthetic and functional problems. It is necessary to develop a novel treatment strategy for ameloblastoma, but there are currently no innovative treatments. Although our understanding of the molecular biological mechanisms of ameloblastoma is still insufficient, there have been many recent reports of new molecular biological findings on ameloblastoma. Therefore, bioactive factors that have potential for novel therapeutic methods, such as molecular targeted therapy, have been discovered in ameloblastoma. In this review, we summarize the molecular biological findings of ameloblastoma reported over several decades, focusing on factors involved in invasion into surrounding tissues and disease-specific gene mutations. We also mention the effect of the interaction between tumour cells and stromal components in ameloblastoma on tumour development. Scientific field of dental Science: Oral surgery, Odontogenic tumor, Ameloblastoma.

Upregulation of interleukin-8 and activin A induces osteoclastogenesis in ameloblastoma

Ameloblastoma is a common odontogenic benign tumor located in the jaws and is characterized by severe local bone destruction. The current study aimed to investigate the effect of interactions between tumor cells and bone marrow stromal cells (BMSCs) on osteoclast formation in ameloblastoma. The impact of ameloblastoma/BMSC interactions on cytokine production, gene expression and osteoclastogenesis was examined using an immortalized ameloblastoma cell line that the authors' previously established. The results demonstrated that interactions between ameloblastoma cells and BMSCs increased interleukin (IL)‑8 and activin A secretion by BMSCs. IL‑8 expression in BMSCs was modulated by tumor‑derived tumor necrosis factor‑α and IL‑8 contributed to osteoclast formation not only directly but also by stimulating receptor activator of NF‑κB ligand (RANKL) expression in BMSCs. Activin A secretion in BMSCs was stimulated by ameloblastoma cells via cell‑to‑cell‑mediated activation of c‑Jun N‑terminal kinase activation, acting as a cofactor of RANKL to induce osteoclast formation and function. The present study highlights the critical role of communication between BMSCs and ameloblastoma cells in bone resorption in ameloblastoma.

Comparison of osteoclastogenesis and local invasiveness of ameloblastoma and keratocystic odontogenic tumor

Objectives:

The aim of this study was to compare the expression of receptor-activated nuclear factor kappa B (RANK) with its ligand (RANKL) and matrix metalloproteinase-2 (MMP2) in solid/multicystic ameloblastomas (ABs) and keratocystic odontogenic tumors (KOTs).

Materials and Methods:

The expression of MMP2, RANK, and RANKL molecules was evaluated in 13 ABs and 14 KOTs by immunohistochemistry. The expressions were calculated in the odontogenic epithelial cells as well as the stromal cells.

Results:

Odontogenic epithelia of AB expressed MMP2, RANK, and RANKL significantly higher than that of KOTs (P < 0.05). The expression of MMP2, RANK, and RANKL was highest in plexiform subtype (79.9%, 81.08%, and 65.1%, respectively). KOTs without daughter epithelia nests expressed both MMP2 and RANK the least (56.06% and 47.5%, respectively). Stromal cells, on the other hand, expressed similar MMP2 pattern in odontogenic epithelia of both AB and KOT. RANKL was expressed weaker in the stromal cells of both lesions.

Conclusion:

Invasive biological and osteolytic behaviors of both lesions were evaluated in this study. It was found to be more in AB than keratocystic odontogenic. A significant expression of MMP2, RANK, and RANKL in both KOTs associated with microcyst and plexiform type AB as well.

Dysregulation of AKT1, a miR-138 target gene, is involved in the migration and invasion of tongue squamous cell carcinoma

BACKGROUND

AKT1, also known as PKBα, is abnormally expressed in various malignancies. In this study, we aimed to evaluate the role of AKT1 in the tongue squamous cell carcinoma (TSCC) and further clarify the mechanisms of AKT1 in the migration and invasion of TSCC.

METHODS

At first, immunohistochemistry (IHC) was conducted to detect the expression of AKT1 in TSCC. Then, we determined the role of AKT1 in the migration and invasion of TSCC and further investigated whether AKT1 was the target gene of miR-138 using dual luciferase reporter assays and Western blot.

RESULTS

Immunohistochemistry results suggested that AKT1 dysregulation was a frequent event in TSCC, and upregulation of AKT1 was correlated with lymph node metastasis and associated with reduced overall survival. UM1 cells with higher migratory and invasive abilities had more robust AKT1 protein expression than UM2 cells with lower migratory and invasive abilities. The migration and invasion abilities were inhibited in UM1 cells upon AKT1 knockdown, meanwhile resulted in a decline of metastasis-related proteins (vimentin, slug, and pERK1/2), and upregulation of E-cadherin. Luciferase assays revealed that AKT1 was directly targeted by miR-138, and ectopic transfection of miR-138 reduced the expression of AKT1 protein.

CONCLUSIONS

Our results confirm that upregulation of AKT1, a miR-138 target gene, is a frequent event in TSCC and contributes to the aggressive behaviors and poor prognosis of TSCC.

Immunohistochemistry of Five Molecular Markers for Typing and Management of Ameloblastomas: A Retrospective Analysis of 40 Cases

PURPOSE

The aims of this study are to elucidate if molecular markers can be used to differentiate between the two main types of ameloblastoma (unicystic and solid/multicystic), and to determine whether a biologically 'less-aggressive' subtype exists.

METHODS

A retrospective analysis of 33 solid/multicystic ameloblastomas and six unicystic ameloblastomas was completed using immunohistochemistry for five molecular markers: P16, P53, MMP-9, Survivin, and Ki-67. Tumors were graded as either negative or positive (mild, moderate, strong), and the results were related to both ameloblastoma subtypes and outcomes following treatment.

RESULTS

Unicystic ameloblastomas were more likely to test strongly positive for P53 than solid/multicystic ameloblastomas (p < 0.05), whereas the latter were more likely to be negative for Survivin (p < 0.05). Solid/multicystic and Type 3 unicystic ameloblastomas that were positive for P16, but also negative for MMP-9 and Survivin, were less likely to recur than all other tumors (p < 0.05). The proliferation index of an ameloblastic carcinoma (11 %) was shown to be higher than benign ameloblastomas (4.5 %).

CONCLUSIONS

Immunohistochemistry can be valuable in lesions where histological sub-typing of an ameloblastoma is unclear. A biologically 'less-aggressive' subtype may exist, and hence further research into this area is required.

Quantitative evaluation of microvessel density using CD34 in clinical variants of ameloblastoma: An immunohistochemical study

Background:

Odontogenic epithelium plays an important role in the histogenesis of odontogenic tumors of the jaws. Ameloblastomas, which arise from odontogenic epithelium, are considered benign with little tendency to metastasize. Tumors require an adequate supply of oxygen and a way to remove their waste products. This can be achieved by angiogenesis. In situ quantification of the microvessel density (MVD) is a usual method for assessing angiogenesis. Moreover, angiogenesis may differ in subtypes of ameloblastomas and could play a role in determining the pattern of tumor growth.

Aim:

The aim of the present study was to demonstrate the expression of cluster of differentiation (CD34) in variants of ameloblastomas and to correlate and compare their expression to the aggressive behavior.

Materials and Methods:

A retrospective cross-sectional study which included forty paraffin blocks was conducted after obtaining ethical committee clearance. Ten cases of pyogenic granuloma were used as a positive control and thirty cases were of solid multicystic ameloblastoma (SMA), unicystic ameloblastoma (UA) and desmoplastic ameloblastomas. Angiogenesis was assessed using CD34 antigen and was immunohistochemically localized. Statistical analysis was carried out for comparative analysis with the help of ANOVA test, Kolmogorov–Smirnov test and least significance difference test.

Results:

A significant correlation was obtained between the MVD of all the three variants, i.e., SMA, UA and desmoplastic ameloblastomas which was statistically significant (P < 0.05).

Conclusion:

Increased MVD in the three variants, i.e., SMA, UA and desmoplastic ameloblastoma seen in the present study could suggest that the angiogenesis has an important role in tumor progression and aggressiveness of ameloblastomas.

PRL-3 promotes migration and invasion and is associated with poor prognosis in salivary adenoid cystic carcinoma

BACKGROUND

PRL-3 had been found to be involved in tumorigenesis in various malignancies. In this study, we investigated the role of PRL-3 in the development, migration, and invasion of salivary adenoid cystic carcinoma (SACC).

METHODS

Immunohistochemistry (IHC) was used to analyze the role of PRL-3 in the development and prognosis of SACC. Then, we overexpressed or inhibited the expression of PRL-3 in paired SACC cells to analyze the role of PRL-3 in the migration and invasion of SACC. In vitro migration and invasion assays were used. Western blotting was used to detect metastasis-related protein levels.

RESULTS

IHC results confirmed that the deregulation of PRL-3 was a frequent event in SACC; the upregulation of PRL-3 was related to clinical stages, vital status, and distant metastasis, which was associated with reduced overall survival and disease-free survival. SACC-LM cells with higher migratory and invasive abilities had more robust PRL-3 protein expression than SACC-83 cells with lower migratory and invasive abilities. PRL-3 overexpression promoted cell migration, invasion, and proliferation, led to simultaneous upregulation of phosphorylated PRL-3, pERK1/2, Slug, vimentin, and downregulation of E-cadherin in SACC-83 cells. However, the inhibition of PRL-3 by PRL-3 inhibitor or PRL-3 siRNA in SACC-LM cells inhibited cell migration, invasion, and proliferation, resulted in simultaneous downregulation of phosphorylated PRL-3, pERK1/2, Slug, vimentin, and upregulation of E-cadherin.

CONCLUSIONS

Our results confirm that PRL-3 plays an important role in the development of SACC and contributes to the migratory and invasive abilities of SACC.

Deregulation of Bmi-1 is associated with enhanced migration, invasion and poor prognosis in salivary adenoid cystic carcinoma

BACKGROUND

Bmi-1 had been found to involve in self renewal of stem cells and tumorigenesis in various malignancies. In this study, we investigated the role of Bmi-1 in the development of salivary adenoid cystic carcinoma (SACC).

METHODS

At first, we confirmed that the deregulation of Bmi-1 was a frequent event in SACC; up-regulation of Bmi-1 was correlated with clinical stages, vital status and distant metastasis and associated with reduced overall survival and disease free survival. SACC-LM cells, higher migration and invasion abilities, elevated the expression of Bmi-1 protein, epithelial-mesenchymal transition (EMT) related proteins (Snail, Slug and Vimentin) and cancer stem cells (CSCs) related proteins (ABCG2, Notch, ALDH-1, Oct-4, Nanog and Epcam) compared to the SACC-83 cells (lower migration and invasion abilities). The migration and invasion abilities were inhibited in SACC-LM cells upon Bmi-1 knockdown. Meanwhile, Bmi-1 knockdown resulted in simultaneous loss of stem cell markers and EMT markers in SACC-LM cells.

CONCLUSION

Our studies confirm that Bmi-1 deregulation plays an important role in the development of SACC and contributes to the migration and the invasion abilities of SACC, which is involved in EMT and CSCs.

GENERAL SIGNIFICANCE

To our knowledge, this is the first study revealing that Bmi-1 deregulation is associated with enhanced migration, invasion and poor prognosis in salivary adenoid cystic carcinoma.

EGFR signaling downstream of EGF regulates migration, invasion, and MMP secretion of immortalized cells derived from human ameloblastoma

Ameloblastoma is an odontogenic tumor characterized by local invasiveness and frequent recurrence. The surrounding stroma, composed of different cell types and extracellular matrix (ECM), may influence ameloblastoma invasive behavior. Furthermore, tumor and stromal cells secrete matrix metalloproteases (MMPs), which, in turn, can modulate the matrix and promote the release of ECM-bound growth factors. Among these growth factors, epidermal growth factor (EGF) and its receptor, EGFR, have already been shown to stimulate MMP synthesis, suggesting that an interdependent mechanism, involving MMP activity and growth factors release, may contribute to tumor invasiveness. The aim of this study was to evaluate the effects of the EGF/EGFR signaling pathway on migration, invasion, and MMP activity, in a primary cell line derived from human ameloblastoma. We established and characterized a primary cell line (AME-1) from a human ameloblastoma sample. This cell line was transduced with human papillomavirus type 16 (HPV16) E6/E7 oncogenes, generating the AME-HPV continuous cell line. EGF, MMP2, and MMP9 expression in ameloblastoma biopsies and in the AME-HPV cell line was analyzed by immunohistochemistry and immunofluorescence, respectively. Migratory activity of EGF-treated AME-HPV cells was investigated using monolayer wound assays and Transwell chambers. EGF-induced invasion was assessed in Boyden chambers coated with Matrigel. Conditioned medium from EGF-treated cells was subjected to zymography. EGFR expression in AME-HPV cells was silenced by small interfering RNA (siRNA), to verify the relationship between this receptor and MMP secretion. Ameloblastoma samples and AME-HPV cells expressed EGF, EGFR, MMP2, and MMP9. AME-HPV cells treated with EGF showed increased rates of migration and invasion, as well as enhanced MMP2 and MMP9 activity. EGFR knockdown decreased MMP2 and MMP9 levels in AME-HPV cells. EGFR signaling downstream of EGF probably regulates migration, invasion, and MMP secretion of ameloblastoma-derived cells.

Chronic exposure to carbon nanotubes induces invasion of human mesothelial cells through matrix metalloproteinase-2

Malignant mesothelioma is one of the most aggressive forms of cancer known. Recent studies have shown that carbon nanotubes (CNTs) are biopersistent and induce mesothelioma in animals, but the underlying mechanisms are not known. Here, we investigate the effect of long-term exposure to high aspect ratio CNTs on the aggressive behaviors of human pleural mesothelial cells, the primary cellular target of human lung mesothelioma. We show that chronic exposure (4 months) to single- and multiwalled CNTs induced proliferation, migration, and invasion of the cells similar to that observed in asbestos-exposed cells. An up-regulation of several key genes known to be important in cell invasion, notably matrix metalloproteinase-2 (MMP-2), was observed in the exposed mesothelial cells as determined by real-time PCR. Western blot and enzyme activity assays confirmed the increased expression and activity of MMP-2. Whole genome microarray analysis further indicated the importance of MMP-2 in the invasion gene signaling network of the exposed cells. Knockdown of MMP-2 in CNT and asbestos-exposed cells by shRNA-mediated gene silencing effectively inhibited the aggressive phenotypes. This study demonstrates CNT-induced cell invasion and indicates the role of MMP-2 in the process.

AFM nanoindentation detection of the elastic modulus of tongue squamous carcinoma cells with different metastatic potentials

Although significant advances have been made in understanding the molecular mechanisms that influence tongue squamous cell carcinoma (TSCC) metastasis, less is known about the association between the cellular elastic modulus and TSCC metastasis. Atomic force microscopy (AFM) nanoindentation via the rate-jump method was used to detect the elastic modulus of TSCC cells from patients and cell lines with different metastatic potentials. TSCC cells with higher metastatic potential showed decreases in the elastic modulus compared to TSCC cells with lower metastatic potential. Moreover, the decrease in elastic modulus was accompanied with epithelial-mesenchymal transition (EMT), cytoskeleton (F-actin and β-tubulin) changes, small nucleus size and large nucleus/cytoplasm (N/C) ratio. The present findings demonstrate a close relationship between the cellular elastic modulus and the metastasis of TSCC. The elastic modulus detected by AFM nanoindentation via the rate-jump method can potentially be used to grade the metastatic potential of TSCC.

FROM THE CLINICAL EDITOR

This team of investigators report the use of an atomic force microscopy-based method to determine the elastic modulus of tongue squamous cell carcinoma cells, and demonstrate that such cells with higher metastatic potential show decreased elastic modulus compared to cells with lower metastatic potential.

Molecular markers of tumor invasiveness in ameloblastoma: An update

The aim of the present article was to review the current new knowledge on the molecular markers of tumor invasion in ameloblastoma. In this review, tumor molecular markers were identified and allocated to the following six groups according to their functions: (I) Markers involved in extracellular matrix degradation, (II) Molecular markers involved in cell adhesion lost, (III) Molecular markers involved in bone remodeling, (IV) Cytokines involved in angiogenesis, (V) Molecular markers related with the function of tumor stromal cells on the invasion of ameloblastoma, and (VI) Molecular markers involved in cell proliferation related with invasion.

In general, the location of markers within the tumor and not their quantitative assessments as such is emphasized. Data showed that the correlation among molecular markers of invasive relevance is still not quite clear. Results on markers of tumor invasion and metastatic potential appeared to be too premature for a statement regarding the instinct invasive nature of ameloblastoma. The unraveling of specific new details concerning these mechanisms, whereby the expression and relationships among the molecules are mediated, may provide an opportunity to afford efficient prevention and develop new treatment therapies.

Piwil2 modulates the proliferation and metastasis of colon cancer via regulation of matrix metallopeptidase 9 transcriptional activity

Piwi-like protein 2 (Piwil2) has recently emerged as a putative oncogene which is amplified in several human malignancies. However, the role of Piwil2 in colon cancer remains poorly understood. The aim of this study was to investigate the clinical and pathological significance of Piwil2, and the possible role in the proliferation and metastasis of colon cancer. Primary colon cancer paired with adjacent normal colon tissue and lymph node metastasis (LNM) lesions in 66 patients' tissue microarrays (TMA) were used to determine the expression of Piwil2. Knocked down Piwil2 expression in SW620 and SW480 colon cancer cell lines was performed to evaluate the role of Piwil2 in cell proliferation, invasion, metastasis in vitro and tumorigenicity in vivo. The possible roles of Piwil2 in the regulation of a 2 kb matrix metallopeptidase 9 (MMP9) promoter fragment and on the regulation of apoptotic pathways were evaluated by using a luciferase reporter construct and Western blots, respectively. Significantly higher expression levels of Piwil2 were observed in primary colon cancer tissue and in LNM in comparison with normal colon mucosa. Piwil2 expression significantly correlated with more aggressive clinical and pathological parameters with poorer five-year metastasis-free survival and overall survival. Piwil2 silencing significantly reduced cancer cell proliferation, colony formation ability and increased apoptosis in vitro and inhibited tumor growth in vivo. Piwil2 knockdown also attenuated migration and invasion of colon cancer cells via modulation of MMP9 transcriptional activities. Our results indicate that Piwil2 moderates the proliferation and metastasis potential of colon cancer.

Expression of phosphorylated mTOR and its regulatory protein is related to biological behaviors of ameloblastoma

The present study investigated the relationship between the expression of p-mTOR, p-4EBP1 and p-p70S6K in the cytoplasm and nucleus of ameloblastoma (AB) cells and the invasiveness of ABs. Immunohistochemistry was performed to detect the expression of p-mTOR, p-4EBP1 and p-p70S6K in ABs and the level of these proteins in the nucleus and cytoplasm was scored. There was ectopic expression of p-mTOR in ABs. 27 AB patients were positive for p-mTOR expression in the nucleus and 47 for p-mTOR expression in the cytoplasm. The ectopic expression of p-4EBP-1 was also noted. 23 patients (27%) were positive for p-4EBP-1 expression in the nucleus and 55 (64.7%) for p-4EBP-1 expression in the cytoplasm. The ectopic expression of p-p70S6K was also noted. Of these patients, 33 were positive for p-p70S6K expression in the nucleus (38.8%) and 45 for p-p70S6K expression in the cytoplasm (52.9%). Statistical analysis showed the expression of three proteins in the nucleus of patients with recurrent cancer was markedly higher than that in those with primary cancer. The expression of p-mTOR, p-4E-BP1 and p-p70S6K in the nucleus was related to the invasiveness of ABs. Multivariable analysis with Cox proportional hazards model showed the p-mTOR expression had influence on AB recurrence (OR: 6.417, 95%CI: 1.428-28.824). The possibility of AB recurrence in patients with nuclear p-mTOR expression was 6.417 folds higher than that in those with cytoplasmic p-mTOR expression. The nuclear expression of p-mTOR, p-4E-BP1 and p-p70S6K was associated with biological behaviors (invasiveness) of ABs, and p-mTOR was an independent predictor of AB.

Epigenetic regulation of matrix metalloproteinase expression in ameloblastoma

BACKGROUND

An ameloblastoma is a benign odontogenic neoplasm with aggressive behaviour and high recurrence rates. The increased expression of matrix metalloproteinases (MMPs) has been reported in ameloblastomas. In the present study, we hypothesised that epigenetic alterations may regulate MMP expression in ameloblastomas.

METHODS

We investigated the methylation status of the genes MMP-2 and MMP-9 in addition to mRNA transcription and protein expression in ameloblastomas. Methylation analysis was performed by both methylation-specific polymerase chain reaction (MSP-PCR) and restriction enzyme digestion to evaluate the methylation profile of MMP-2 and MMP-9 in 12 ameloblastoma samples and 12 healthy gingiva fragments, which were included as controls. Furthermore, we investigated the transcription levels of the genes by quantitative reverse-transcription PCR (qRT-PCR). Zymography was performed to verify protein expression in ameloblastomas.

RESULTS

The ameloblastomas showed a high frequency of unmethylated MMP-2 and MMP-9, whereas the healthy gingival samples presented a sharp prevalence of methylated MMPs. Higher expression levels of MMP-9 were found in ameloblastomas compared to healthy gingiva. However, no significant differences in the MMP-2 mRNA expression between groups was found. All ameloblastomas showed positive expression of MMP-2 and MMP-9 proteins.

CONCLUSIONS

Our findings suggest that expression of MMP-9 is increased in ameloblastomas and is possibly modulated by unmethylation of the gene.

Manganese superoxide dismutase induces migration and invasion of tongue squamous cell carcinoma via H2O2-dependent Snail signaling

Our previous studies had revealed that the dysregulation of manganese superoxide dismutase (SOD2) expression was a frequent event in tongue squamous cell carcinoma (TSCC) and may be associated with enhanced metastatic potential. To further evaluate the mechanism of SOD2-mediated metastasis in TSCC, TSCC cell lines with different metastatic potentials (i.e., the highly metastatic UM1 line and the UM2 line, which displays fewer metastases) were used. Compared to UM2 cells, UM1 cells exhibited significantly higher SOD2 activity and intracellular H(2)O(2); higher protein levels of Snail, MMP1, and pERK1/2; lower protein levels of E-cadherin; and no difference in catalase activity. Upon knockdown of SOD2 by RNA interference, UM1 cells displayed significantly reduced migration and invasion abilities; reduced activities of SOD2; lower intracellular H(2)O(2); decreased protein levels of Snail, MMP1, and pERK1/2; and increased protein levels of E-cadherin. The migration and invasion abilities of UM2 and SOD2 shRNA-transfected UM1 cells were enhanced by H(2)O(2) treatment and accompanied by increased protein levels of Snail, MMP1, and pERK1/2 and decreased protein levels of E-cadherin. Moreover the migration and invasion abilities of UM1 cells were decreased after catalase treatment. Thus, we conclude that the SOD2-dependent production of H(2)O(2) contributes to both the migration and the invasion of TSCC via the Snail signaling pathway, through increased Snail, MMP1, and pERK1/2 protein levels and the repression of the E-cadherin protein.

Review article: Current concepts of ameloblastoma pathogenesis

Ameloblastoma is a locally destructive and invasive tumour that can recur despite adequate surgical removal. Molecular studies have offered interesting findings regarding ameloblastoma pathogenesis. In the present review, the following topics are discussed regarding its molecular nature: clonality, cell cycle proliferation, apoptosis, tumour suppressor genes, ameloblastin and other enamel matrix proteins, osteoclastic mechanism and matrix metalloproteinases and other signalling molecules. It is clear from the literature reviewed that translational studies are necessary to identify prognostic markers of ameloblastoma behaviour and to establish new diagnostic tools to the differential diagnosis of unicystic from multicystic ameloblastoma. Finally, molecular biology studies are also important to develop more effective alternative approaches to the treatment of this aggressive odontogenic tumour.

Expression of RECK and matrix metalloproteinase-2 in ameloblastoma

Background

Ameloblastoma is a frequent odontogenic benign tumor characterized by local invasiveness, high risk of recurrence and occasional metastasis and malignant transformation. Matrix metalloproteinase-2 (MMP-2) promotes tumor invasion and progression by destroying the extracellular matrix (ECM) and basement membrane. For this proteolytic activity, the endogenous inhibitor is reversion-inducing cysteine rich protein with Kazal motifs (RECK). The aim of this study was to characterize the relationship between RECK and MMP-2 expression and the clinical manifestation of ameloblastoma.

Methods

Immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR) were employed to detect the protein and mRNA expression of RECK and MMP-2 in keratocystic odontogenic tumor (KCOT), ameloblastoma and ameloblastic carcinoma.

Results

RECK protein expression was significantly reduced in KCOT (87.5%), ameloblastoma (56.5%) and ameloblastic carcinoma (0%) (P < 0.01), and was significantly lower in recurrent ameloblastoma compared with primary ameloblastoma (P < 0.01), but did not differ by histological type of ameloblastoma. MMP-2 protein expression was significantly higher in ameloblastoma and ameloblastic carcinoma compared with KCOT (P < 0.01). RECK mRNA expression was significantly lower in ameloblastoma than in KCOT (P < 0.01), lower in recurrent ameloblastoma than in primary ameloblastoma, and was negative in ameloblastic carcinoma. MMP-2 mRNA expression was significantly higher in ameloblastoma compared with KCOT (P < 0.01), but was no different in recurrent ameloblastoma versus primary ameloblastoma. RECK protein expression was negatively associated with MMP-2 protein expression in ameloblastoma (r = -0.431, P < 0.01).

Conclusion

Low or no RECK expression and increased MMP-2 expression may be associated with negative clinical findings in ameloblastoma. RECK may participate in the invasion, recurrence and malignant transformation of ameloblastoma by regulating MMP-2 at the post-transcriptional level.

Protein phosphatase 1A (PPM1A) is involved in human cytotrophoblast cell invasion and migration

Trophoblast invasion is crucial for embryo implantation and placentation. Excessive trophoblast invasion leads to hydatidiform moles and choriocarcinoma. PPM1A is a phosphatase which dephosphorylates and inactivates a broad range of substrates, including TGF-beta, MAP kinases, p38 and JNK kinase cascades, and is involved in tumor suppression. The objective of this study was to investigate the expression of PPM1A in normal and malignant human placenta and its role in trophoblast invasion, which shares many similarities with invasion of tumor cells. By Western blotting and immunocytochemistry, significantly higher expression of PPM1A in human placental villi at term was found as compared with that during the first trimester. Furthermore, the expression level of PPM1A protein in hydatidiform moles was lower compared with that during normal pregnancy. We further investigated the function of PPM1A in extravillous trophoblast cell line HTR8/SVneo. Transwell migration and Matrigel invasion assays demonstrated that PPM1A siRNA significantly promoted the motility and invasiveness of the cells. Gelatin zymography showed that knockdown of PPM1A with siRNA elevated the expression of pro-matrix metalloproteinase pro-(MMP)-9, but down-regulated tissue inhibitors of metalloproteinases (TIMP)-2. The present data indicate that PPM1A plays a critical role in the regulation of normal placentation by inhibiting trophoblast migration and invasion.

Suppression of matrix metalloproteinase-2 via RNA interference inhibits pancreatic carcinoma cell invasiveness and adhesion

AIM: To investigate the inhibitory effects of RNA interference (RNAi) on expression of matrix metalloproteinase-2 (MMP-2) gene and invasiveness and adhesion of human pancreatic cancer cell line, BxPC-3.

METHODS: RNAi was performed using the vector (pGPU6)-based small interference RNA (siRNA) plasmid gene silence system to specifically knock down MMP-2 expression in pancreatic cancer cell line, BxPC-3. Four groups of different specific target sequence in coding region of MMP-2 and one non-specific sequence were chosen to construct four experimental siRNA plasmids of pGPU6-1, pGPU6-2, pGPU6-3 and pGPU6-4, and one negative control siRNA plasmid of pGPU6 (-). MMP-2 expression was measured by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. Cell proliferation and apoptosis were examined by methyl thiazolyl tetrazolium (MTT) and flow cytometry, respectively. The abilities of adhesion and invasion were detected by cell adhesion assay and cell invasion assay using Transwell chambers.

RESULTS: The expression of MMP-2 was inhibited and the inhibitory effects of different sequence varied. pGPU6-1 group had the most efficient inhibitory effect, followed by pGPU6-2 and pGPU6-3 groups. Invasiveness and adhesion were more significantly reduced in pGPU6-1, pGPU6-2 and pGPU6-3 groups as compared with pGPU6 (-) and blank control groups. However, no difference concerning cell proliferation and apoptosis was observed after transfection between experiment groups and control groups.

CONCLUSION: RNAi against MMP-2 successfully inhibited the mRNA and protein expression of MMP-2 in the pancreatic cancer cell line, BxPC-3, leading to a potent suppression of tumor cell adhesion and invasion without affecting cell proliferation and apoptosis. These findings suggest that the RNAi approach towards MMP-2 may be an effective therapeutic strategy for the clinical management of pancreatic tumor.