Comparative Evaluation of Laminin 1 Expression in Odontogenic Keratocyst, Dentigerous Cyst, and Ameloblastoma: An Immunohistochemical Study

Maya Ramesh; Vinod Thomas; Balakrishnan Sekar; Jissy George

doi:10.4103/jofs.jofs_64_19

ORIGINAL ARTICLE

Year : 2019 | Volume : 11 | Issue : 1 | Page : 59-64

Comparative Evaluation of Laminin 1 Expression in Odontogenic Keratocyst, Dentigerous Cyst, and Ameloblastoma: An Immunohistochemical Study

Maya Ramesh, Vinod Thomas, Balakrishnan Sekar, Jissy George
Department of Oral Pathology, VMSDC, Salem, Tamil Nadu, India

Date of Web Publication

9-Aug-2019

Correspondence Address:
Dr. Maya Ramesh
Department of Oral Pathology, Vinayaka Missions Saankarachariyar Dental College, Salem, Tamil Nadu
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jofs.jofs_64_19

Abstract

Introduction: Odontogenic keratocysts, dentigerous cysts, and ameloblastoma are the most common forms of cystic pathology that affect the jaw bones. The purpose of this study was to assess the immunohistochemical expression of laminin 1 in these lesions and to study the probable role of laminin 1 in their biologic behavior. Materials and Methods: Serial sections of 4 µm were obtained from the archival blocks using standard microtome. One set of sections was used for immunohistochemical study. Presence of brown colored end product at the site of target antigen was considered as positive immunoreactivity. Results: Of the 10 ameloblastomas, 9 were positive. Among the 10 odontogenic keratocysts, 9 showed a positive immunoreactivity for laminin 1 and 1 case was negative. Among the 10 dentigerous cysts, all of them showed a positive immunoreactivity for laminin 1. A statistical analysis was carried out using chi-square test and the statistical significance was evaluated. Discussion: All the lesions that showed positive immunoreactions for laminin 1 had basement membrane immunolocalization. The laminin 1 in odontogenic keratocysts showed that it is not involved in the formation of daughter cysts and the separation of epithelium and surrounding connective tissue. Conclusion: Expression of laminin 1 in the stellate reticulum can be a sign of the aggressiveness of ameloblastoma. Laminin 1 expression in the lining epithelium of dentigerous cyst can be used to explain its potential to transform to ameloblastoma. It can be concluded that the nature and aggressiveness of odontogenic cysts and tumors can be explained using laminin 1.

Keywords: Laminin 1, odontogenic keratocyst, dentigerous cyst, ameloblastoma, immunohistochemistry

How to cite this article:
Ramesh M, Thomas V, Sekar B, George J. Comparative Evaluation of Laminin 1 Expression in Odontogenic Keratocyst, Dentigerous Cyst, and Ameloblastoma: An Immunohistochemical Study. J Orofac Sci 2019;11:59-64

How to cite this URL:
Ramesh M, Thomas V, Sekar B, George J. Comparative Evaluation of Laminin 1 Expression in Odontogenic Keratocyst, Dentigerous Cyst, and Ameloblastoma: An Immunohistochemical Study. J Orofac Sci [serial online] 2019 [cited 2023 Jun 9];11:59-64. Available from: https://www.jofs.in/text.asp?2019/11/1/59/264187

Introduction

Odontogenic cysts, odontogenic keratocysts (OKC), and ameloblastoma are the most common forms of cystic lesions and tumors that affect the jaw bones region.^[1] Laminins represent a growing family of glycoproteins constituting the basement membrane. They are known to direct many biological processes. With respect to carcinogenesis, laminins play an important role in cell adhesion, mitogenesis, differentiation, and even metastasis.^[2]

In 1967, Toller suggested that the OKC may best be regarded as a benign neoplasm rather than a conventional cyst based on its clinical behavior.^[3] Various investigations have focused on it due to its biological activities, high tendency to recur, and different growth mechanisms in comparison to other cystic lesions.^[4] In 2005, the WHO reclassified the lesion as a tumor and named it as keratocystic odontogenic tumor (KCOT) from 2005 to 2017.^[3] In 2017, it reverted to the earlier name, as the new WHO/IARC classification reclassified OKC back into the cystic category.^[5]

The laminins are a family of glycoproteins that provide an integral part of the structural scaffolding of basement membranes in almost every animal tissue. Each laminin is a heterotrimer assembled from α, β, and λ chain subunits, secreted and incorporated into cell-associated extracellular matrices.^[6]

Overexpression of laminin receptor on tumor cells is implicated in their attachment at sites distant from the primary lesion, and laminin’s ability to induce production of Type IV collagenase likely aids in degradation and penetration of basement membrane by these metastatic tumor cells.^[7] The benign nature of some odontogenic cysts and the aggressive behavior of others could be explained by the expression of laminin 1.^[1]

Expression of laminin 1 in normal oral mucosa, odontogenic cysts, and odontogenic tumors was examined in several studies. In previous studies, it was found that sections of odontogenic tumors stained for laminin 1 showed strong reactivity at the basement membrane junction as well as in the cytoplasm of all tumor cells. Accordingly, it was suggested that the expression of laminin 1 in the cytoplasm of the tumor cells, but not in the normal mucosa, may be a useful marker to distinguish these two types of epithelium. This may suggest that laminin 1 influences the proliferation activity toward tumor potential.^[1]

The purpose of this study was to assess the immunohistochemical expression of laminin 1 in odontogenic keratocyst, dentigerous cyst, and ameloblastoma and to study the probable role of laminin 1 in their biological behavior.

Aim and Objectives

The aim of this study was to analyze and compare the immunohistochemical expression of laminin 1 in odontogenic keratocyst, dentigerous cyst, and ameloblastoma in order to understand the possible role of laminin 1 in their biological behavior.

Materials and Methodology

Ethical clearance was obtained for the study from the Institutional Ethical Committee, Vinayaka Missions Sankarachariyar Dental College with approval No. VMSDC/IEC/Approval No.046 dated December 29, 2014. The present study was carried out in archival blocks taken from the Department of Oral Pathology, comprising 10 histopathologically proven cases of dentigerous cyst, 10 histopathologically proven cases of odontogenic keratocyst, and 10 histopathologically proven cases of ameloblastoma. Inclusion criteria were histopathologically proven cases of dentigerous cyst, odontogenic keratocyst, and ameloblastoma involving maxilla and mandible. Recurrent cases and cysts showing secondary inflammation were excluded. Serial sections of 5 µm were obtained from the archival blocks using standard microtome. One set of sections was stained with routine hematoxylin and eosin. The other set of sections was used for immunohistochemical study.

Immunohistochemical staining was done using Ventana Benchmark GX. The protocol of the instrument was followed in the procedure. The stained slides were exited from the instrument.

Presence of brown-colored end product at the site of target antigen was considered as positive immunoreactivity. The expression of laminin 1 was determined to be either positive or negative. Cytoplasmic and membranous staining was observed, which was considered as positive immunoreaction. Based on the intensity of staining, it was categorized as mild staining, moderate staining, and strong staining, respectively. Based on the pattern of distribution, the staining was categorized as focal and diffuse.

Results

A total of 30 cases (n = 30), comprising 10 ameloblastoma (n = 10), 10 odontogenic keratocysts (n = 10), and 10 dentigerous cysts (n = 10) were evaluated for immunohistochemical expression, intensity, location of expression, and expression pattern of laminin 1.

Of the 10 ameloblastomas, 8 (80%) were follicular ameloblastoma and 2 (20%) were plexiform ameloblastoma. The expression intensity among the different types of ameloblastoma was also evaluated. Among the 10 cases of ameloblastoma, 9 (90%) showed a positive immunoreactivity for laminin 1 and 1 (10%) case was negative [Table 1]. Of the nine ameloblastomas, two (22%) showed mild expression and seven (78%) showed moderate expression [Table 2]. Of the nine ameloblastomas, five (56%) showed diffuse staining and four (44%) showed focal staining, respectively [Table 3]. Among the nine ameloblastomas, five (56%) showed basement membrane staining and four (44%) showed both basement membrane and stellate reticulum staining [Table 4]; [Figure 1] and [Figure 2].

Table 1 Immunohistochemical expression status of laminin 1 in ameloblastoma, odontogenic keratocyst, and dentigerous cyst

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Table 2 Intensity of immunohistochemical expression of laminin 1 in ameloblastoma, odontogenic keratocyst, and dentigerous cyst

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Table 3 Pattern of immunohistochemical expression of laminin 1 in ameloblastoma, odontogenic keratocyst, and dentigerous cyst

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Table 4 Location of immunohistochemical expression of laminin 1 in ameloblastoma, odontogenic keratocyst, and dentigerous cyst

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Figure 1 40× high-power view showing moderate stellate reticulum and basement membrane staining of laminin 1 in follicular ameloblastoma.

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Figure 2 40× high-power view showing moderate stellate reticulum and basement membrane staining of laminin 1 in plexiform ameloblastoma.

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Of the 10 OKC, 9 (90%) showed a positive immunoreactivity for laminin 1 and 1 (10%) case was negative [Table 1]. Of the nine odontogenic keratocyst cases, eight (89%) showed mild expression and one (11%) showed moderate expression [Table 2]. Among the nine odontogenic keratocysts, three (33%) showed diffuse staining and six (67%) showed focal staining [Table 3]. All the nine (100%) OKC showed basement membrane expression [Table 4]; [Figure 3].

Figure 3 40× high-power view showing moderate basement membrane staining of laminin 1 in odontogenic keratocyst.

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All the 10 (100%) dentigerous cysts showed a positive immunoreactivity for laminin 1 [Table 1]. Of the 10 dentigerous cysts, 5 (50 %) showed mild expression and 5 (50%) showed moderate expression [Table 2]. Among the 10 dentigerous cysts, 6 (60%) showed diffuse staining and 4 (40%) showed focal staining [Table 3]. All the 10 (100%) dentigerous cysts showed both basement membrane and epithelial staining [Table 4]; [Figure 4].

Figure 4 40× high-power view showing epithelial staining of laminin 1 in dentigerous cyst.

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A statistical analysis was carried out using chi-square test and the statistical significance was evaluated. When immunohistochemical expression status of laminin 1 in ameloblastoma, odontogenic keratocyst, and dentigerous cyst was compared using chi-square test, p-value was found to be 0.585 and this was not significant. When intensity of immunohistochemical expression of laminin 1 in ameloblastoma, odontogenic keratocyst, and dentigerous cyst was compared using chi-square test, p-value was found to be 0.017 and this was significant. When the pattern of immunohistochemical expression of laminin 1 in ameloblastoma, odontogenic keratocyst, and dentigerous cyst was compared using chi-square test, p-value was found to be 0.470 and this was not significant. When the location of immunohistochemical expression of laminin 1 in ameloblastoma, odontogenic keratocyst, and dentigerous cyst was compared using chi-square test, p-value was found to be 0.001 and this was significant.

Discussion

Important cellular functions attributed to laminin include stimulation of growth and differentiation, neurite outgrowth promotion, and mediation of cell communication. Laminin is the first ECM protein detected during embryogenesis; it is present at the two-cell stage in the mouse embryo. In later development and in mature tissue, it serves as a ubiquitous and major noncollagenous component of basement membranes. It participates in the assembly of this specialized form of the ECM and mediates cell attachment and maintenance of the differentiated state of epithelial and endothelial cell layers that are intimately associated with their basement membranes. ^[8]

In this study, of the 10 cases of ameloblastoma, 9 (90%) showed a positive immunoreactivity for laminin 1 and 1 (10%) case was negative. Abd El-Latif et al.^[1] reported in 2013 that 60% of ameloblastomas showed positive reaction for laminin 1. Poomsawat et al.^[9] in 2007 reported that all the 14 ameloblastomas selected showed positive immunoreactivity for laminin 1. In Bin et al.^[10], 46.4% of the 28 cases of ameloblastoma showed positive immunoreactivity for laminin.

In the present study, of the nine ameloblastomas, five (56%) showed basement membrane staining and four (44%) showed both basement membrane and stellate reticulum staining. In Bin et al.,^[10] in 28 cases of ameloblastoma, the positive expression of laminin was mainly located in the basement membrane and the cytoplasm of some cells. Poomsawat et al.^[9] in 2007 reported that linear deposits of laminin 1 was found at the epithelial–mesenchymal junction and was expressed in all tumor cells. With respect to carcinogenesis, laminins play an important role in cell adhesion, mitogenesis, differentiation, and even metastasis. ^[2]

Of the 10 odontogenic keratocyst, 9 (90%) showed a positive reaction for laminin 1 and 1 (10%) case was negative. Abd El-Latif et al.^[1] in 2013 reported that 50% of OKC showed positive reaction for laminin 1. Poomsawat et al.^[9] in 2006 reported that all the 20 OKC showed positive immunoreactivity for laminin 1. Ayoub et al. in 2011^[11] reported that 1 case out of the 12 cases of OKC revealed immunopositive reaction to laminin 1, representing 8.3%. In the study by Amorim et al.,^[12] negative areas for laminin predominated in the basement membrane in OKC. Gurgel et al.^[13] investigated the expression of laminin 1 in 20 cases of OKC and found that laminin 1 was expressed in all cases.

Of the nine OKC cases, eight (89%) showed mild expression and one (11%) showed moderate expression. In another study by Gurgel et al.,^[13] in 20 OKC cases, laminin 1 labeling intensity was weak in 3 (15%) cases, moderate in 5 (25%), and strong in 12 (60%) cases. In the study by Poomsawat et al.,^[9] in odontogenic cysts, all cysts showed strong intensity for laminin 1.

All the nine (100%) OKC showed basement membrane expression only. In another study by Ayoub et al.,^[11] the immunopositive reaction appeared as brown linear staining at the basement membrane of the epithelial cells in OKC. In the study by Poomsawat et al.,^[9] OKC exhibited continuous linear deposits for laminin 1 at the basement membrane. Gurgel et al.^[13] in their study on 20 OKC cases found that laminin 1 immunolocalization was predominantly continuous in 18 (90%) OKC, including areas of acanthosis, subepithelial split, and epithelial buds.

All the 10 (100%) dentigerous cysts showed a positive immunoreactivity for laminin 1. In a similar study by Abd El-Latif et al.,^[1] all dentigerous cysts showed positive reaction for laminin 1. In a study by Poomsawat et al., of the dentigerous cysts, 20 cysts showed positive reaction for laminin 1.

In this study, of the 10 dentigerous cysts, 5 (50%) showed mild expression and 5 (50%) showed moderate expression. In the study by Poomsawat et al.^[9], all odontogenic cysts showed strong intensity for laminin 1.

All the 10 (100%) dentigerous cysts showed both basement membrane and epithelial staining. In the study by Abd El-Latif et al.,^[1] in odontogenic cysts, the immunopositive reaction appeared as brown linear staining at the basement membrane of the epithelial cells in most of the cases. Few cases exhibited positive immunoreactivity at the basement membrane junction as well as in the cytoplasm of epithelial cells. In the study by Poomsawat et al.,^[9] dentigerous cysts exhibited continuous linear deposits for laminin 1 at the basement membrane.

Conclusion

Laminin is a component of the basement membrane. In this study, all the lesions that showed positive immunoreactions for laminin 1 had basement membrane immunolocalization.

Absence of expression of laminin 1 in the basement membrane can be a sign of invasion or recurrence. In this study, all the OKC showed positive reaction for laminin 1 only at the basement membrane, indicating that laminin 1 is not involved in the formation of daughter cysts and the separation of epithelium and surrounding connective tissue in OKC. Expression of laminin 1 in the stellate reticulum can be a sign of aggressiveness of ameloblastoma. Laminin 1 expression in the lining epithelium of dentigerous cyst can be used to explain the potential of dentigerous cysts to transform to ameloblastoma. It can be concluded that the nature and aggressiveness of odontogenic cysts and tumors can be explained using laminin 1.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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