REVIEW OF SCIENTIFIC ARTICLES
|Year : 2008 | Volume
| Issue : 1 | Page : 48-49
Review of scientific articles
Department of Oral and Maxillofacial Pathology, Meenakshi Ammal Dental College and Hospital, Chennai, India
Department of Oral and Maxillofacial Pathology, Meenakshi Ammal Dental College and Hospital, Chennai
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Kavitha B. Review of scientific articles. J Oral Maxillofac Pathol 2008;12:48-9
Ameloblastoma and adenomatoid odontogenic tumor: The role of α2 β 1, α 3β 1, and α5 B, integrins in local invasiveness and architectural characteristics
Andrade ESS, Miguel MCC, Pinto LP, de Souza LB
Annals of Diagnostic Pathology 2007,11:199-205
This study was aimed to analyze the role of α2β1, α3β1 and α5β1 integrins in cellular and cell-matrix interactions in ameloblastomas and adenomatoid odontogenic tumors (AOTS) and to establish their role in the biologic behavior of these lesions. Extracellular matrix proteins (ECM) have been shown to play an important role in epithelial mesenchymal interactions in odontogenic tumors.
Many types of cells are unable to proliterate in the absence of anchorage to an extracellular substrate. This anchorage to ECM proteins is mediated by integrins and studies have demonstrated a correlation between integrin expression and the biologic behavior of some tumors. Integrins are transmembrane receptors consisting of two noncovalently linked glycoprotein sub units (one α and one β sub unit) that modulate cell to cell and cell-matrix binding and are implicated in growth, adhesion, migration, proliferation, apoptosis and cellular morphology.
30 ameloblastoms (20 solid and 10 unicystic tumors) and 12 AOTS were selected for the study, and α2β1, α3β1, and α5β1 were the integrins that were studied. In uni-cystic ameloblastomos, α5β1 integrin expression was predominant compared with α3β1 integrin explaining less aggressiveness of these tumors compared with solid type. However, this hypothesis cannot be completely confirmed because no significant difference in the intensity of integrin labeling was observed between solid and unicystic ameloblastomas.
Both types of ameloblastomas had a tendency toward a focal labeling of α3β1 integrin which is known to be an important laminin receptor. This focal expression of α3β1 integrin may lead to basement membrane disorganization in some regions, thus contributing to the infiltrative behaviour of ameloblastomas.
Between ameloblastomas and AOTs, ameloblastoma presented a stronger labeling for α5β1 integrins. Integrin α5β1 is the classic receptor of fibronectin, a protein that plays an important role in epithielial - mesenchymal interaction in odontogenic tumors. Binding of α5β1 to fibronectin increases the secretion and expression of metalloproteinases. Thus α5β1 integrin plays a greater role in invasion of ameloblastomas and agents that block integrins may help in the study and the development of strategies for the treatment and control of invasiveness of ameloblastomas.
Dual effect of nitric oxide in immortalized and malignant human oral keratinocytes: induction of apoptosis and differentiation
Lee SK, Kim HS, Lee HJ, Lee J, Jeon BH, Jun CD, Lee SK, Kim EC
J Oral Pathol Med 2006,35:352-60
Nitric oxide (NO), a reactive nitrogen intermediate, is a short-lived free radical synthesized via the L-arginine to L-citruline pathway, which is mediated by nitric oxide synthase (NOS). NO is generally considered to be an inducer of apoptosis in may cell types (including oral cancer cells), but also it protects other cell types from apoptosis.
This study investigates the influence of NO on the proliferation, cell cycle, apoptosis, and differentiation of immortalized human oral keratinocytes (IHOK) and primary oral cancer cells (HN4 cells) using MTT assay, sulforhodamine B assay, flow cytometry, nuclear DNA staining and western blotting. Sodium nitroprusside (SNP) is the NO donor. IHOK ad HN4 cells treated at SNP concentrations more than 1mM showed up-regulated apoptosis-related protein expression, while lower concentration of SNP enhanced the expression of keratinocyte differentiation markers (cytodifferentiation) in IHOK andHN4 cells. Thus, this study highlights the dual effects of NO i.e. induction of apoptosis or cytodifferentiation at different concentrations, implicating its possibility in anti-oral cancer treatment.
Myofibroblasts in stroma of odontogenic cysts and tumors can contribute to variations in the biologic behaviour of lesions
Vered M, Shohat I, Buchner A, Dayan D
Oral Oncology 2005,41:1028-1033
Myofibroblasts (MF) are fibroblasts with smooth-muscle like features and most MF express alpha smooth muscle actin (αSMA), an actin isoform typically found in vascular smooth muscle cells. MF have a role in the synthesis of extracellular matrix (ECM) and in force generation, which results in ECM reorganization and tissue contraction during wound healing.
MFs are found in normal tissues (Lymph nodes, blood vessels, uterine submucosa, lung septa) and in pathologic conditions (reactive lesions, Benign tumors, Fibromatoses and sarcomas). Many pathologic conditions of the oral mucosa and the jaw bones contain MF (Nodular fascitis, giant cell fibroma, peripheral giant cell granuloma, cyclosporin induced gingival hyperplasia). Earlier it was assumed that MF were part of the host reaction to prevent invasion of malignant cells, but now evidence points towards their promotive role in invasions.
In the present study IHC assessment of the frequency of stromal myofibroblasts in different odontogenic cysts ad tumors (Dentigerous cysts, OKC (ortho & para) ameloblastic fibroodontoma, Unicystic ameloblostoma and solid ameloblastoma) was done.
Results showed that mean MFs were more in para-OKC than in DC. In tumors, MFs were more in SAM than in UAM and AMF/O. The high frequency of stromal MF in known aggressive odontogenic lesions, such as OKC-P and SAM, implies that MF can contribute to the biological behavior of these odontogenic lesions and the author suggests that agents that control stromal MF can be used as an aid to reduce extensive and multilating surgery in cases of remarkably aggressive odontogenic lesions.
Altered CD 40 and E-Cadherin expression - Putative role in Oral Lichen Planus
Neppelberg E, Loro LL, Oijordsbakken G, Johannessen AC
J Oral Pathol Med 2007,36:153-60
Changes in the basal cell compartment have been a matter of particular interest in research on OLP and increased apoptosis confined to the basal cell region has been demonstrated. Earlier studies indicate that intraepithelial cytotoxic T cells are involved in direct targeting of keratinocytes for apoptosis
In this study, the expression of CD 40, CD 44 and epithelial (E) - Cadherin was investigated in 22 patients with OLP and compared with 13 controls. In actively diseased areas of OLP lesions, basal keratinocytes did not express CD 40 and were focally E-Cadherin - negative, in contrast to non-diseased areas and normal oral mucosa. Intra-epithelial T-Cells expressing CD 40 and CD40L were demonstrated. This study suggests that CD40 - CD 40L system orchestrate inflammatory T-Cell responses both in the epithelium and subepithelial cell infiltrate. As basal keratinocytes down regulate CD40, they escape CD40 - CD40L - induced apoptosis in OLP suggesting other mechanisms of triggering apoptosis. Loss of E-cadherins in basal keratinocytes may contribute to reduced basal cell structural integrity allowing enhanced T-Cell migration into the epithelial compartment in OLP.
Commensal oral bacteria antigens prime human dendritic cells to induce Th1, Th2 or Treg differentiation
Kopita AN, Ihan Hren N, Ihan A
Oral Microbiol Immunol 2006,21:1-5
Bacterial flora induce an immune response which results in inflammatory manifestations. This study was aimed to test the capacity of distinct oral bacterial antigens (Streptococcus mitis, Propionibacterium acnes es spp.) to prime human dendritic cells for stimulation of the T-Lymphocyte response. To assess the T-lymphocyte response, the expression of CD 25, CD 69, intracellular interferon (CIFN-γ) and intracellular interleukin 4 (CIL-4) was determined.
Dendritic cells, primed with antigens of Bacteroides fragilis have shown significantly higher activation and expression of IFN-γ by T lymphocytes compared to negative controls. Those primed with P. acnes had no effect on T-lymphocyte activation or cytokine production but instead induced differentiation of T lymphocytes into regulatory T cells with a potentially inhibitory effect on immune response. Dendritic cells primed with antigens of S. mitis induced increased expression of CIL-4.This understanding of immunopathologic manifestations in the oral cavity may offer new possibilities for redirecting immune responses in mucosal vaccination.