TGF-β1, Smad-2/-3, Smad-1/-5/-8, and Smad-4 signaling factors are expressed in ameloblastomas, adenomatoid odontogenic tumors, and calcifying cystic odontogenic tumors: an immunohistochemical study

Tumor microenvironment of ameloblastoma with a focus on osteoclastogenesis, cell migration, and malignant transformation

BACKGROUND

Odontogenic tumors arise in the jawbone and originate from cells associated with tooth development. Therefore, understanding odontogenic tumors requires knowledge of all aspects of dental research, including tooth development and eruption. Ameloblastoma is the most common odontogenic tumor.

HIGHLIGHT

Although a benign tumor, ameloblastoma progresses with marked jawbone resorption. Because of its locally aggressive features, it can be treated surgically by resecting the surrounding bone. From a molecular pathology perspective, several genetic mutations and dysregulated signaling pathways involved in ameloblastoma tumorigenesis have been identified. Histopathologically, ameloblastomas consist of peripheral ameloblast-like cells and an inner stellate reticulum. The stromal region consists of fibrovascular connective tissue, showing a characteristic sparse myxoid histology. In general, the tumor microenvironment, including the surrounding non-tumor cells, contributes to tumorigenesis and progression. In this review, we focus on the tumor microenvironment of ameloblastomas. In addition, we present some of our recent studies on osteoclastogenesis, tubulin acetylation-induced cell migration, and hypoxia-induced epithelial-mesenchymal transition in ameloblastomas.

CONCLUSION

Further research on ameloblastomas can lead to the development of new treatments and improve patients' quality of life.

The IL-1β-p65 axis stimulates quiescent odontogenic epithelial cell rests via TGF-β signalling to promote cell proliferation of the lining epithelia in radicular cysts: A laboratory investigation

AIM

Cyst formation of the jaws is frequently accompanied by the proliferation of odontogenic epithelial cells located in the periodontal ligament (PDL), which consists of heterozygous cells and includes the most fibroblasts. The lining epithelium of radicular cyst, an odontogenic cyst of inflammatory origin, is derived from the proliferation of the remnants of the Hertwig epithelial root sheath (odontogenic epithelial cell rests of Malassez; ERMs) in the PDL. ERMs are maintained at a lower proliferative state under physiological conditions, but the regulatory mechanisms underlying the inflammation-dependent enhanced-proliferative capabilities of ERMs are not fully understood. The aim of this study was to evaluate the effects of cytokine pathway association between TGF-β signalling and IL-1β signalling on the regulation of odontogenic epithelial cell proliferation using radicular cyst pathological specimens and odontogenic epithelial cell lines.

METHODOLOGY

Immunofluorescence analyses were performed to clarify the expression levels of Smad2/3 and Ki-67 in ERMs of 8-week-old mouse molar specimens. In radicular cyst (n = 52) and dentigerous cysts (n = 6) specimens from human patients, the expression of p65 (a main subunit of NF-κB), Smad2/3 and Ki-67 were investigated using immunohistochemical analyses. Odontogenic epithelial cells and PDL fibroblastic cells were co-cultured with or without an inhibitor or siRNAs. Odontogenic epithelial cells were cultured with or without TGF-β1 and IL-1β. The proliferative capabilities and Smad2 phosphorylation levels of odontogenic epithelial cells were examined.

RESULTS

Immunohistochemically, Smad2/3-positivity was increased, and p65-positivity and Ki-67-positivity were decreased both in ERMs and in the epithelial cells in dentigerous cysts, a non-inflammatory developmental cyst. In contrast, p65-positive cells, along with the expression of Ki-67, were increased and Smad2/3-positive cells were decreased in the lining epithelia of radicular cysts. Co-culture experiments with odontogenic epithelial cells and PDL fibroblastic cells revealed that PDL cells-derived TGF-β1/2 and their downstream signalling suppressed odontogenic epithelial cell proliferation. Moreover, TGF-β1 stimulation induced Smad2 phosphorylation and suppressed odontogenic epithelial cell proliferation, while IL-1β stimulation reversed these phenotypes through p65 transactivation.

CONCLUSIONS

These results suggest that IL-1β-p65 signalling promotes odontogenic epithelial cell proliferation through suppressing TGF-β-Smad2 signalling, which would be involved in the pathogenesis of radicular cysts.

Association of MDM2 Overexpression in Ameloblastomas with MDM2 Amplification and BRAFV600E Expression

Ameloblastoma is a rare tumor but represents the most common odontogenic neoplasm. It is localized in the jaws and, although it is a benign, slow-growing tumor, it has an aggressive local behavior and high recurrence rate. Therefore, alternative treatment options or complementary to surgery have been evaluated, with the most promising one among them being a targeted therapy with the v-Raf murine sarcoma viral oncogene homologue B (BRAF), as in ameloblastoma the activating mutation V600E in BRAF is common. Studies in other tumors have shown that the synchronous inhibition of BRAF and human murine double minute 2 homologue (MDM2 or HDM2) protein is more effective than BRAF monotherapy, particularly in the presence of wild type p53 (WTp53). To investigate the MDM2 protein expression and gene amplification in ameloblastoma, in association with BRAFV600E and p53 expression. Forty-four cases of ameloblastoma fixed in 10% buffered formalin and embedded in paraffin were examined for MDM2 overexpression and BRAFV600E and p53 expression by immunohistochemistry, and for MDM2 ploidy with fluorescence in situ hybridization. Sixteen of forty-four (36.36%) cases of ameloblastoma showed MDM2 overexpression. Seven of sixteen MDM2-positive ameloblastomas (43.75%) were BRAFV600E positive and fifteen of sixteen MDM2-positive ameloblastomas (93.75%) were p53 negative. All MDM2 overexpressing tumors did not show copy number alterations for MDM2. Overexpression of MDM2 in ameloblastomas is not associated with MDM2 amplification, but most probably with MAPK activation and WTp53 expression. Further verification of those findings could form the basis for the use of MDM2 expression as a marker of MAPK activation in ameloblastomas and the trial of dual BRAF/MDM2 inhibition in the management of MDM2-overexpressing/BRAFV600E-positive/WTp53 ameloblastomas.

TGF-β Signaling in Progression of Oral Cancer

Oral cancer is a common malignancy worldwide, accounting for 1.9% to 3.5% of all malignant tumors. Transforming growth factor β (TGF-β), as one of the most important cytokines, is found to play complex and crucial roles in oral cancers. It may act in a pro-tumorigenic and tumor-suppressive manner; activities of the former include cell cycle progression inhibition, tumor microenvironment preparation, apoptosis promotion, stimulation of cancer cell invasion and metastasis, and suppression of immune surveillance. However, the triggering mechanisms of these distinct actions remain unclear. This review summarizes the molecular mechanisms of TGF-β signal transduction, focusing on oral squamous cell and salivary adenoid systemic carcinomas as well as keratocystic odontogenic tumors. Both the supporting and contrary evidence of the roles of TGF-β is discussed. Importantly, the TGF-β pathway has been the target of new drugs developed in the past decade, some having demonstrated promising therapeutic effects in clinical trials. Therefore, the achievements of TGF-β pathway-based therapeutics and their challenges are also assessed. The summarization and discussion of the updated knowledge of TGF-β signaling pathways will provide insight into the design of new strategies for oral cancer treatment, leading to an improvement in oral cancer outcomes.

The effect of exenatide (a GLP-1 analogue) and sitagliptin (a DPP-4 inhibitor) on asymmetric dimethylarginine (ADMA) metabolism and selected biomarkers of cardiac fibrosis in rats with fructose-induced metabolic syndrome

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthesis, is a risk factor for endothelial dysfunction, a common pathophysiological denominator for both atherogenesis and cardiac fibrosis. We aimed to investigate whether the cardioprotective and antifibrotic effects of incretin drugs, exenatide and sitagliptin, may be associated with their ability to affect circulating and cardiac ADMA metabolism. Normal and fructose-fed rats were treated with sitagliptin (5.0/10 mg/kg) or exenatide (5/10 µg/kg) for 4 weeks. The following methods were used: LC-MS/MS, ELISA, Real-Time-PCR, colorimetry, IHC and H&E staining, PCA and OPLS-DA projections. Eight-week fructose feeding resulted in an increase in plasma ADMA and a decrease in NO concentration. Exenatide administration into fructose-fed rats reduced the plasma ADMA level and increased NO level. In the heart of these animals exenatide administration increased NO and PRMT1 level, reduced TGF-ß1, α-SMA levels and COL1A1 expression. In the exenatide treated rats renal DDAH activity positively correlated with plasma NO level and negatively with plasma ADMA level and cardiac α-SMA concentration. Sitagliptin treatment of fructose-fed rats increased plasma NO concentration, reduced circulating SDMA level, increased renal DDAH activity and reduced myocardial DDAH activity. Both drugs attenuated the myocardial immunoexpression of Smad2/3/P and perivascular fibrosis. In the metabolic syndrome condition both sitagliptin and exenatide positively modulated cardiac fibrotic remodeling and circulating level of endogenous NOS inhibitors but had no effects on ADMA levels in the myocardium.

TGF-β signaling pathway: Therapeutic targeting and potential for anti-cancer immunity

Transforming growth factor-β (TGFβ) is a pleiotropic secretory cytokine exhibiting both cancer-inhibitory and promoting properties. It transmits its signals via Suppressor of Mother against Decapentaplegic (SMAD) and non-SMAD pathways and regulates cell proliferation, differentiation, invasion, migration, and apoptosis. In non-cancer and early-stage cancer cells, TGFβ signaling suppresses cancer progression via inducing apoptosis, cell cycle arrest, or anti-proliferation, and promoting cell differentiation. On the other hand, TGFβ may also act as an oncogene in advanced stages of tumors, wherein it develops immune-suppressive tumor microenvironments and induces the proliferation of cancer cells, invasion, angiogenesis, tumorigenesis, and metastasis. Higher TGFβ expression leads to the instigation and development of cancer. Therefore, suppressing TGFβ signals may present a potential treatment option for inhibiting tumorigenesis and metastasis. Different inhibitory molecules, including ligand traps, anti-sense oligo-nucleotides, small molecule receptor-kinase inhibitors, small molecule inhibitors, and vaccines, have been developed and clinically trialed for blocking the TGFβ signaling pathway. These molecules are not pro-oncogenic response-specific but block all signaling effects induced by TGFβ. Nonetheless, targeting the activation of TGFβ signaling with maximized specificity and minimized toxicity can enhance the efficacy of therapeutic approaches against this signaling pathway. The molecules that are used to target TGFβ are non-cytotoxic to cancer cells but designed to curtail the over-activation of invasion and metastasis driving TGFβ signaling in stromal and cancer cells. Here, we discussed the critical role of TGFβ in tumorigenesis, and metastasis, as well as the outcome and the promising achievement of TGFβ inhibitory molecules in the treatment of cancer.

Regulation of transforming growth factor-β signaling as a therapeutic approach to treating colorectal cancer

According to data from 2020, Slovakia has long been among the top five countries with the highest incidence rate of colorectal cancer (CRC) worldwide, and the rate is continuing to rise every year. In approximately 80% of CRC cases, allelic loss (loss of heterozygosity, LOH) occurs in the long arm of chromosome 18q. The most important genes that can be silenced by 18q LOH or mutations are small mothers against decapentaplegic homolog (SMAD) 2 and SMAD4, which are intracellular mediators of transforming growth factor (TGF)-β superfamily signals. TGF-β plays an important role in the pro-oncogenic processes, including such properties as invasion, epithelial-mesenchymal transition (commonly known as EMT), promotion of angiogenesis, and immunomodulatory effects. Several recent studies have reported that activation of TGF-β signaling is related to drug resistance in CRC. Because the mechanisms of drug resistance are different between patients in different stages of CRC, personalized treatment is more effective. Therefore, knowledge of the activation and inhibition of factors that affect the TGF-β signaling pathway is very important.

The Effect of LncRNA H19 on Human Dental Pulp Cells Through Tumor Growth Factor-β1 (TGF-β1)/Smad Signaling Pathway

The pulp tissue is located in the pulp cavity of tooth and has the ability of nutrition, feeling, and defense. Human dental pulp cells (hDPCs) are the main cells of pulp with the ability to self-renew and multi-directional differentiation. LncRNA H19 is involved in the regulation of human dental pulp stem cells, but the specific mechanism has not been elucidated. hDPCs were isolated and cultured in vitro to measure vimentin expression by immunohistochemistry (IHC). hDPCs were randomly assigned into control group, negative control (NC) group and lncRNA H19 overexpression group followed by measuring lncRNA H19, DSPP, and DMP-1 mRNA expression, cell proliferation, ALP activity, BMP-2 expression by ELISA, TGF-β1, Smad2, and Smad4 expression by Western blot. hDPCs were positive for vimentin staining and confirmed to be derived from mesenchymal. Transfection of pcDNA3.1-LncRNA H19 plasmid significantly increased LncRNA H19 expression, promoted cell proliferation, enhanced ALP activity, upregulated DSPP and DMP-1, elevated BMP-2 expression in cell supernatant, as well as promoted TGF-β1, Smad2, and Smad4 expressions compared with control (P < 0.05). In conclusion, lncRNA H19 facilitates hDPCs differentiation into odontoblasts by promoting cell proliferation and increasing BMP-2 secretion via regulating TGF-β1/Smad signaling pathway.

Immunohistochemical Evaluation of Transforming Growth Factor-β Expression in Oral Lichen Planus

Background: In oral lichen planus (OLP), which is a persistent inflammatory condition of the autoimmune system, cytotoxic T lymphocytes are triggered against epithelial cells. OLP resists treatment more than its cutaneous counterpart and potentially transforms into malignancy as oral squamous cell carcinoma (OSCC). Transforming growth factor β (TGF-β) is produced by various cells, such as leukocytes and epithelial cells, whereby epithelial-mesenchymal-epithelialn (EMT) forms the phenotype of invasive cancerous cells and promotes tumors. Objectives: We investigated the role of TGF-β in the pathogenesis and biological behavior of dysplastic and non-dysplastic OLP. Methods: Thirty samples of erosive/atrophic OLP (15 dysplastic and 15 non-dysplastic) and 10 samples of normal mucosa of the oral cavity were immunohistochemically examined for the expression of TGF-β. Statistical analysis was performed using the Kruskal-Wallis and chi-squared tests. Results: TGF-β expressed to varying degrees in the epithelium of the studied groups. The groups significantly differed in terms of the expression of TGF-β. In pairwise comparisons, the dysplastic OLP group showed significantly higher immunoreactivity than the normal and non-dysplastic groups, although there was no significant difference between the normal and non-dysplastic OLP groups. The expression of TGF-β in the sub-epithelial lymphocytes of the dysplastic and non-dysplastic OLP groups showed a statistically significant difference. Conclusions: According to the results, TGF-β, as a marker of the inflammatory process in chronic inflammatory conditions, was expressed in epithelial cells and sub-epithelial lymphocytes of all OLPs. This suggests a possible role of this marker in the pathogenesis of OLP. In addition, the increased expression of TGF-β, a marker also involved in carcinogenesis, in the epithelial keratinocytes indicates the role it might play in the development of carcinoma in OLP.

Odontogenic carcinosarcoma with dentinoid: a rare case report

Odontogenic carcinosarcoma is a very rare malignant odontogenic tumor, characterized by malignant epithelial and mesenchymal components. Studies have reported several cases of odontogenic carcinosarcoma, mainly in the upper and lower jaws, with malignant clinical manifestations. Herein, we present the case of a 58-year-old woman with odontogenic carcinosarcoma with dentinoid in the left maxilla. The invasion range was large, and the left maxillary molar was missing. Histology revealed odontogenic carcinosarcoma with bidirectional differentiation characteristics and comprising three components: malignant epithelium, malignant interstitium, and dentinoid. The patient subsequently underwent nasal endoscopic sinus tumor resection, and she recovered well after surgery. After a strict 4-year follow-up, to date, there are still no signs of disease or local recurrence. To our knowledge, this is the first reported case of odontogenic carcinosarcoma with dentinoid. Our study describes the clinical, morphological, and immunohistochemical characteristics of this case, and distinguishes it from related diseases.

The effects of inhibiting the activation of hepatic stellate cells by lignan components from the fruits of Schisandra chinensis and the mechanism of schisanhenol

Liver fibrosis is a pathological manifestation induced by chronic liver injury and may cause cirrhosis and liver cancer with the chronic progression of fibrosis. During the onset and progression of liver fibrosis, the activation of hepatic stellate cells (HSCs) is the core mechanism for the secretion of many extracellular matrices to induce fibrosis. Lignans are reportedly the main effective components of Schisandra chinensis with good anti-fibrosis effects. In this study, we compared the inhibiting effects of the seven lignan components from S. chinensis on HSC activation. We found that the seven lignans inhibited the activation of human HSCs (LX-2) in various degrees. Among all lignans, schisanhenol showed the best effect in inhibiting the activation of LX-2 with a dose-effect relationship. Sal also inhibited the phosphorylations of Smad1, Smad2, Smad3, extracellular regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK), p38, and nuclear transcription factor-κB (NF-κB), as well as downregulated Smad4. All these findings suggested that schisanhenol may ameliorate liver fibrosis by inhibiting the transforming growth factor β (TGF-β)/Smad and mitogen-activated protein kinase (MAPK) signaling pathways. Remarkably, schisanhenol may be a potential anti-liver fibrosis drug and warrants further research.

TGF-β secreted by tumor-associated macrophages promotes proliferation and invasion of colorectal cancer via miR-34a-VEGF axis

Tumor-associated macrophages (TAMs) were reported to be involved in colorectal cancer (CRC) progression. However, its biological role and underlying mechanism in CRC remained to be elucidated. In this study, the expressions of the macrophage marker CD68 and transforming growth factor β1 (TGF-β1) in CRC tumor tissues and adjacent tissues were detected by immunohistochemistry. The expression levels of miR-34a, TGF-β1 and vascular endothelial growth factor (VEGF) in CRC tumor tissues and peripheral blood macrophages were measured by quantitative real-time PCR (qRT-PCR) and western blot. TGF-β1 levels in culture supernatant were detected by ELISA. The cell proliferation and invasion of human CRC cell lines CL187 and HCT116 were determined by MTT assay and Transwell assay, respectively. The results showed that the expression of miR-34a was downregulated whereas TGF-β1 and VEGF were upregulated in CRC tumor tissues and peripheral blood macrophages. TGF-β1 secreted by TAMs promoted the proliferation and invasion of CRC cells. TGF-β1-mediated miR-34a downregulation contributed to the proliferation and invasion of CRC cells via upregulating VEGF. MiR-34a in vivo exerted anti-tumor effect in CRC via inhibiting VEGF expression. In conclusion, TGF-β1 secreted by TAMs promoted CRC proliferation and invasion through regulating miR-34a/VEGF axis.

Is podoplanin expression associated with transforming growth factor-β signaling in odontogenic cysts and tumors?

BACKGROUND

Induction of podoplanin by transforming growth factor-β (TGF-β) has been shown in a number of lesions but not in odontogenic tumors (OTs). We evaluated the association between these markers in OTs for the first time and compared their expression among the different neoplasms.

METHODS

Immunohistochemistry using monoclonal antibody against podoplanin and TGF-β was performed on 76 odontogenic cysts and tumors. Spearman's correlation coefficient, Kruskal-Wallis, and Mann-Whitney U tests followed by adjustment with Bonferroni were used for statistical analysis (P < .05).

RESULTS

A significant difference in podoplanin expression was found among the lesions consisting of solid ameloblastomas, adenomatoid odontogenic tumors, ameloblastic fibromas, odontogenic myxomas (OMs), odontogenic keratocysts, and calcifying odontogenic cysts. Significant differences were observed only between OMs and each of the other neoplasms. Podoplanin immunostaining in the connective tissue was absent in most lesions. TGF-β was significantly different among the study sample but not between the lesions in paired comparisons. None of the studied OTs showed significant correlations between podoplanin-TGF-β, in either the epithelium or the stroma. These markers were also descriptively reported in calcifying epithelial odontogenic tumors.

CONCLUSIONS

The inductive effect of TGF-β on podoplanin seems to be limited, if any, in odontogenic lesions. Podoplanin appears to play a role in some aspects of OTs with epithelial or mixed origins. Despite the possible participation of podoplanin in tumorigenesis, it may not necessarily be involved in the aggressive behavior of OTs.

The distribution and potential prognostic value of SMAD protein expression in chronic lymphocytic leukemia

The SMAD proteins are responsible for transducing signals from activated transforming growth factor-beta. This is the first study assessing the expression of SMAD-1/8, SMAD-2/3, SMAD-4, and SMAD-7 in chronic lymphocytic leukemia cells with regard to their clinical significance and potential prognostic value. Overexpression of SMAD-1/8 was observed in 160 chronic lymphocytic leukemia patients compared to 42 healthy volunteers (p = 0.023) and was associated with a more progressive course of the disease (p = 0.016). Moreover, the high expression of SMAD-1/8 correlated with other, well-established prognostic factors, including clinical stage (p = 0.010) and lymphocyte doubling time (p = 0.021). The expression of SMAD-4 was lower in chronic lymphocytic leukemia patients compared with the control group (p = 0.003). Importantly, lower SMAD-4 levels correlated with longer progression-free survival (p = 0.009), progressive course of the disease (p = 0.002), advanced clinical stage (p = 0.0004), elevated beta-2-microglobulin and lactate dehydrogenase levels (p < 0.05), shorter lymphocyte doubling time (p = 0.009), and CD38 antigen expression (p = 0.039). In addition, lower SMAD-4 expression correlated with lower apoptotic index (p = 0.0007) and lower expression of receptors for vascular endothelial growth factors VEGFR-1 and VEGFR-2. A significant association was found between the low expression of inhibitory protein SMAD-7 and both zeta-chain-associated protein kinase 70–negative cells (p = 0.04) and lower apoptotic index (p = 0.004). No differences were observed in SMAD-2/3 expression. In conclusion, our results demonstrate a significant correlation between greater SMAD-1/8 and lower SMAD-4 expression in chronic lymphocytic leukemia cells, as well as more progressive outcome and poor prognosis. These data provide supporting evidence that the expression of SMAD proteins plays an important role in disease development and may be considered as a novel, biologic prognostic factor in this disease.

Differential expression of the epithelial mesenchymal transition factors Snail, Slug, Twist, TGF-β, and E-cadherin in ameloblastoma

Epithelial mesenchymal transition (EMT), the transition of epithelial cells into motile mesenchymal cells, plays an important role in embryogenesis, cancer invasion, and metastasis. Ameloblastomas are common epithelial odontogenic tumors, occurring exclusively in the mandible with locally invasive growth. Thirty-seven ameloblastoma cases were evaluated for the involvement of EMT by immunohistochemical staining and western blotting using antibodies against Slug, Snail, Twist, TGF-β, and E-cadherin. Double immunostaining was also performed. Slug and TGF-β were expressed in the nuclei of peripheral and stellate reticulum cells of ameloblastoma nests. Twenty cases of Snail, 36 of Slug, 8 of Twist, and 19 of TGF-β showed strong expression in tumor cells in follicular and plexiform patterns. Expression of Slug and TGF-β increased in regions where the expression of E-cadherin was reduced. EMT was found to be associated with the local invasive growth of ameloblastoma. These data suggest that reduced expression of E-cadherin and over-expression of Slug, Snail, and TGF-β induce EMT. Given that ameloblastomas are characterized by local invasiveness, EMT might be related to their development. Thus, strong expression of Slug and TGF-β and reduced expression of E-cadherin might be related to the local invasiveness of ameloblastoma.

Kallikrein 4 and matrix metalloproteinase-20 immunoexpression in malignant, benign and infiltrative odontogenic tumors

CONTEXT

Matrix metalloproteinase-20 (MMP20) (enamelysin) and kallikrein 4 (KLK4) are enzymes secreted by ameloblasts that play an important role in enamel matrix degradation during amelogenesis. However, studies have shown that neoplastic cells can produce such enzymes, which may affect the tumor infiltrative and metastatic behaviors.

AIMS

The aim of this study is to assess the biological role of MMP20 and KLK4 in odontogenic tumors.

MATERIALS AND METHODS

The enzymes were analyzed immunohistochemically in ameloblastoma, adenomatoid odontogenic tumor (AOT), calcifying epithelial odontogenic tumor, keratocystic odontogenic tumor with or without recurrence and odontogenic carcinoma.

STATISTICAL ANALYSIS USED

Clinicopathological parameters were statistically correlated with protein expression using the Fisher's exact test. Kruskal-Wallis and Wilcoxon-independent methods were used to evaluate the differences in median values.

RESULTS

Positive Immunoexpression was detected in all benign lesions, with a prevalence of 75-100% immunolabeled cells. Patients were predominantly young, Caucasian, female, with slow-growing tumors located in the mandible causing asymptomatic swelling. No KLK4 expression was seen in carcinomas, and the amount of MMP20-positive cells varied between 20% and 80%. Rapid evolution, recurrence and age >60 years characterized the malignant nature of these lesions.

CONCLUSIONS

Data showed that KLK4 and MMP20 enzymes may not be crucial to tumoral infiltrative capacity, especially in malignant tumors, considering the diversity and peculiarity of these lesions. The significant immunoexpression in benign lesions, remarkably in AOT, is likely associated with differentiated tumor cells that can produce and degrade enamel matrix-like substances. This would be expected since the histogenesis of odontogenic tumors commonly comes from epithelium that recently performed a secretory activity in tooth formation.

Binding of MMP-9-degraded fibronectin to β6 integrin promotes invasion via the FAK-Src-related Erk1/2 and PI3K/Akt/Smad-1/5/8 pathways in breast cancer

Fibronectin (FN) has been recognized as the key element in promoting cell adhesion, migration and oncogenic transformation. αvβ6 integrin binds with FN in an RGD-dependent manner and is associated with invasion and poor prognosis in many types of cancers. The extracellular matrix (ECM) is commonly degraded and becomes disorganized in cancers. Previous studies have shown that FN can be degraded into fragments by MMP-9 in vitro; MMP-9 expression is upregulated in breast cancer, therefore, the role of degraded FN in breast cancer progression needs to be investigated. In the present study, expression of β6 integrin in breast cancer tissues was analyzed. The data were quite consistent with the hypothesis that β6 integrin expression is an indicator of poor prognosis. Cell surface expression of β6 integrin was correlated with the invasive behavior of the breast cancer cell lines. MMP-9-degraded FN was used to explore its effects on cell invasion and expression of β6 integrin. The results indicated that MMP-9-degraded FN can adjust constituents of the αvβ6 heterodimers at the early phase and significantly elevate amounts of β6 integrin subunits at a later period. To better elucidate the mechanism by which β6 integrin regulates FN-induced cell migration and invasion, we determined the expression and activity of the downstream kinases of β6 integrin, and elucidated that focal adhesion kinase (FAK)-Src interaction promoted the invasion and migration of breast cancer cells after treatment of MMP-9-degraded FN through the Erk1/2 and PI3K/Akt/Smad‑1/5/8 pathways.

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.

Calcifying Cystic Odontogenic Tumour: immunohistochemical expression of matrix metalloproteinases, their inhibitors (TIMPs and RECK) and inducer (EMMPRIN)

BACKGROUND

Calcifying cyst odontogenic tumour (CCOT) is a rare benign cystic neoplasm of odontogenic origin. MMPs are responsible for extracellular matrix remodelling and, together their inhibitors and inducer, determinate the level of its turnover in pathological processes, leading to an auspicious microenvironment for tumour development. Thus, our goal was to evaluate matrix metalloproteinases (MMPs-2, -7, -9 and -14), their inhibitors (TIMPs-2, -3, -4 and RECK) and its inductor (EMMPRIN) expression in CCOT.

MATERIALS AND METHODS

We used 18 cases of CCOT submitted to immunolocalization of the target proteins and analysed in both neoplastic odontogenic epithelial and stromal compartments.

RESULTS

All molecules evaluated were expressed in both compartments in CCOT. In epithelial layer, immunostaining for MMPs, TIMPs, RECK and EMMPRIN was found in basal, suprabasal spindle and stellate cells surrounding ghost cells and ghost cells themselves, except for MMP-9 and TIMP-2 which were only expressed by ghost cells. In stromal compartment, extracellular matrix, mesenchymal (MC) and endothelial cells (EC) were positive for MMP-2, -7, TIMP-3 and -4, while MMP-9, TIMP-2 and RECK were positive only in MC and MMP-14 only in EC. Statistical significance difference was found between both compartments for MMP-9 (P < 0.001), RECK (P = 0.004) and EMMPRIN (P < 0.001), being more expressed in epithelium than in stroma. Positive correlation between both stromal EMMPRIN and RECK expression was found (R = 0.661, P = 0.003).

CONCLUSIONS

We concluded that these proteins/enzymes are differentially expressed in both epithelium and stroma of CCOT, suggesting an imbalance between MMPs and their inducer/inhibitors may contribute on the tumour behaviour.

Current Concepts and Occurrence of Epithelial Odontogenic Tumors: II. Calcifying Epithelial Odontogenic Tumor Versus Ghost Cell Odontogenic Tumors Derived from Calcifying Odontogenic Cyst

Calcifying epithelial odontogenic tumors (CEOTs) and ghost cell odontogenic tumors (GCOTs) are characteristic odontogenic origin epithelial tumors which produce calcifying materials from transformed epithelial tumor cells. CEOT is a benign odontogenic tumor composed of polygonal epithelial tumor cells that show retrogressive calcific changes, amyloid-like deposition, and clear cytoplasm. Differentially, GCOTs are a group of transient tumors characterized by ghost cell presence, which comprise calcifying cystic odontogenic tumor (CCOT), dentinogenic ghost cell tumor (DGCT), and ghost cell odontogenic carcinoma (GCOC), all derived from calcifying odontogenic cysts (COCs). There is considerable confusion about COCs and GCOTs terminology, but these lesions can be classified as COCs or GCOTs, based on their cystic or tumorous natures, respectively. GCOTs include ameloblastomatous tumors derived from dominant odontogenic cysts classified as CCOTs, ghost cell-rich tumors producing dentinoid materials as DGCTs, and the GCOT malignant counterpart, GCOCs. Many authors have reported CEOTs and GCOTs variably express keratins, β-catenin, BCL-2, BSP, RANKL, OPG, Notch1, Jagged1, TGF-β, SMADs, and other proteins. However, these heterogeneous lesions should be differentially diagnosed to allow for accurate tumor progression and prognosis prediction.

Current concepts and occurrence of epithelial odontogenic tumors: I. Ameloblastoma and adenomatoid odontogenic tumor

Ameloblastomas and adenomatoid odontogenic tumors (AOTs) are common epithelial tumors of odontogenic origin. Ameloblastomas are clinico-pathologically classified into solid/multicystic, unicystic, desmoplastic, and peripheral types, and also divided into follicular, plexiform, acanthomatous, granular types, etc., based on their histological features. Craniopharyngiomas, derived from the remnants of Rathke's pouch or a misplaced enamel organ, are also comparable to the odontogenic tumors. The malignant transformation of ameloblastomas results in the formation of ameloblastic carcinomas and malignant ameloblastomas depending on cytological dysplasia and metastasis, respectively. AOTs are classified into follicular, extrafollicular, and peripheral types. Ameloblastomas are common, have an aggressive behavior and recurrent course, and are rarely metastatic, while AOTs are hamartomatous benign lesions derived from the complex system of the dental lamina or its remnants. With advances in the elucidation of molecular signaling mechanisms in cells, the cytodifferentiation of epithelial tumor cells in ameloblastomas and AOTs can be identified using different biomarkers. Therefore, it is suggested that comprehensive pathological observation including molecular genetic information can provide a more reliable differential diagnosis for the propagation and prognosis of ameloblastomas and AOTs. This study aimed to review the current concepts of ameloblastomas and AOTs and to discuss their clinico-pathological features relevant to tumorigenesis and prognosis.