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Table of Contents
ORIGINAL ARTICLE
Year : 2019  |  Volume : 39  |  Issue : 2  |  Page : 257-262

Immunohistochemical expression of Bcl-2 in oral squamous cell carcinoma: a clinicopathological correlation


1 Department of Oral Pathology, Faculty of Dentistry, Mansoura University, Mansoura, Egypt
2 Department of Pathology, Faculty of Medicine, Mansoura University, Mansoura, Egypt

Date of Submission01-Jun-2019
Date of Acceptance25-Jun-2019
Date of Web Publication30-Sep-2020

Correspondence Address:
MD Marwa M.A Zaki
Department of Pathology, Mansoura University, Mansoura, 35516
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/EGJP.EGJP_33_19

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  Abstract 


Background Oral malignancy includes a group of neoplasms affecting any district of the oral cavity, salivary glands, and pharyngeal regions. Notwithstanding, this term has a tendency to be utilized conversely with oral squamous cell carcinoma (OSCC), which represents the most incessant of every oral neoplasm. It is evaluated that a greater than of 90% of oral neoplasm are OSCC malignancies. The Bcl-2 protein is the encoding result of Bcl-2 proto-oncogene. The overexpression of Bcl-2 protein assumes an imperative part in apoptosis protection in many tumors, including head and neck squamous cell carcinoma.
Aim/objectives This study was conducted to scope and find out the possible role of Bcl-2 in the biological behavior of OSCC.
Methods A total of 20 OSCC cases were immunohistochemically examined for expression of Bcl-2.
Results and conclusions There was significant difference among grades of OSCC regarding Bcl-2 expression. A significant correlation between Bcl-2 expression and clinical staging, nodal infiltration, as well as distant metastasis was observed. We concluded that Bcl-2 may be used as a prognostic factor for OSCC and may aid in decisions on cancer diagnosis and therapy.

Keywords: Bcl-2, immunohistochemically, oral squamous cell carcinoma


How to cite this article:
Abdel Aziz MM, Zaki MM, Farg DA, El Kourdy KA. Immunohistochemical expression of Bcl-2 in oral squamous cell carcinoma: a clinicopathological correlation. Egypt J Pathol 2019;39:257-62

How to cite this URL:
Abdel Aziz MM, Zaki MM, Farg DA, El Kourdy KA. Immunohistochemical expression of Bcl-2 in oral squamous cell carcinoma: a clinicopathological correlation. Egypt J Pathol [serial online] 2019 [cited 2021 Apr 15];39:257-62. Available from: http://www.xep.eg.net/text.asp?2019/39/2/257/296054




  Introduction Top


Oral malignancy includes a group of neoplasms affecting any district of the oral cavity, salivary glands, and pharyngeal regions. Notwithstanding, this term has a tendency to be utilized conversely with oral squamous cell carcinoma (OSCC), which represents the most incessant of every oral neoplasm. It was evaluated that a greater than of 90% of oral neoplasm are OSCC malignancies (Warnakulasuriya, 2009; Walker et al., 2003).

In Egypt, as indicated by National organization in 2003–2004, OSCC constituted ∼2.5% of aggregate malignancies. OSCC incorporates tumors situated in the tongue, floor of the mouth, cheek, gingival edge, and the hard and soft palate. Tongue squamous cell carcinoma is the most predominant kind of oral and maxillofacial tumor, with an estimated more than 10 000 new cases and ∼2000 deaths in the USA in 2015 (Mokhtar et al., 2007).

A definitive dynamic development of tumors and the rate of their development are controlled by overabundance cell creation over cell death. Few tumors result from a high cell turnover, resulting in raised cell proliferation, as in rapidly progressing tumors like leukemia and lymphoma. However, in different tumors, growth happens because of change in the genes that control apoptosis, leading to tumor progression (Kumar et al., 2005).

Such tumors result from a deformity in the direction of programmed cell death (apoptosis), which may add to the pathogenesis and progression of tumor. The Bcl-2 protein is the encoding result of Bcl-2 proto-oncogene. It is situated in the mitochondria, endoplasmic reticulum, and perinuclear membrane. It prevents release of cytochrome C from the mitochondrion to cytoplasm, thereby inhibiting cell apoptosis (Gordeev et al., 2015).

The overexpression of anti-apoptotic Bcl-2 protein assumes an imperative part in apoptosis protection in many tumors, including head and neck squamous cell carcinoma (Trask et al., 2002; Danial and Korsmeyer, 2004; Sharma et al., 2005). Bcl-2 knockdown in SCC cell lines has been appeared to promote apoptosis and sensitize the cells to chemotherapeutic agents. Moreover, molecular focusing of Bcl-2 with little particle inhibitors or short peptides advances apoptosis and chemosensitivity in cells of head and neck SCC (Wolter et al., 2006; Li et al., 2007).

Recently, it was detected that Bcl-2 proteins physically interface with other cell proteins, and the connection between these proteins is essential for cell homeostasis, malignancy improvement, and apoptosis (Cory and Adams, 2002). It is fundamental to comprehend the atomic occasions prompting OSCC and the components associated with initiation and progression of OSCC (Wang et al., 2015).

Materials

Study design and sample collection

This retrospective study included 20 cases previously diagnosed as OSCC, retrieved from archives of the Surgical Pathology Laboratory at Mansoura Oncology Center. Medical records of resected OSCC during the period from December 2014 to December 2015, which were revised before use in the study. Inclusion criteria were the availability of tissue blocks and complete clinical data. Re-examination of hematoxylin and eosin-stained slides was done.

Immunohistochemical staining

Immunohistochemical staining was performed on 4-µm-thick formalin-fixed paraffin-embedded tissue sections with anti-Bcl-2 antibody: mouse monoclonal antibody (Dako, Carpinteria, California, USA).


  Methods Top


Clinical evaluation

The clinical information was gathered from the computerized database of the Oncology Center registry, regarding age, sex, site, lymph node involvement, tumor size, distant metastasis, and recurrence. The cases were evaluated according to TNM staging system of AJCC.

Histological evaluation

From each paraffin block, sections were prepared for hematoxylin and eosin staining to confirm the histological typing and grading of OSCC according to WHO criteria.

Immunohistochemical staining evaluation

Granular cytoplasmic staining of neoplastic cells using monoclonal anti-Bcl-2 antibodies is considered as positive Bcl-2 expression. The percentage of positive cells was evaluated using image analysis software and classified as follows: more than 50% of cells positive, ‘+++’; 25–50% of cells positive, ‘++’; 5–24% of cells positive ‘+,’ and fewer than 5% positive or no staining, ‘–’ (Juneja et al., 2015).

Statistical analysis

Data were analyzed using the computer program statistical package for the social science, version 20 to obtain descriptive data (IBM Corp. Released 2011, IBM SPSS Statistics for Windows, Version 20.0, Armonk, NY: IBM Corp.). In the statistical comparison between the different groups, the significance of difference was tested using χ2 test for categorical variables. A P value of less than 0.05 was considered to be statistically significant.


  Results Top


Twenty cases of OSCC were enrolled in the present study. Patients’ ages ranged between 26 and 82 years, with a mean of 61 years, with the age group of 40–60 years mostly affected. Fifteen (75%) patients were male and five (25%) were female. The most prevalent site of occurrence among all studied cases was the tongue, 11 (55%) cases. Meanwhile, the least frequent sites were encountered in hard palate, with one (5%) case, the parotid, with two (10%) cases, the cheek, with one (5%) case, and floor of mouth, with one (5%) case.

Immunohistochemical results

Bcl-2 granular cytoplasmic staining was observed in 10 cases and complete negative cytoplasmic staining was observed in the remaining 10 cases. On evaluation of intensity of Bcl-2 expression, 5% (1/20) cases showed more than 50% positivity, 10% (2/20) cases showed 25–50% positivity, and 15% (3/20) cases showed 5–24% positivity and 20% (4/20) cases showed less than 5% positivity for Bcl-2 (which was considered as negative staining in addition to the 10 cases with complete negative staining). The total positivity was 30% (6/20). In most of Bcl-2-positive cases, the peripheral cells of epithelial tumor islands were intensely stained, with decreasing immunoreactivity toward the center of the neoplastic nests ([Figure 1],[Figure 2],[Figure 3]). There was no statistically significant relation between Bcl-2 expression and age groups, sex, or affected sites.
Figure 1 Well-differentiated squamous cell carcinoma. (a) Neoplastic sheets with frequent keratin pearls (hematoxylin and eosin, ×100). (b) Neoplastic cells showing negative Bcl-2 cytoplasmic stain (Bcl-2, ×40). (c) Peripherally located cells within infiltrating tumor nests are more intensely stained for Bcl-2 (Bcl-2, ×400).

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Figure 2 Moderately differentiated squamous cell carcinoma. (a) Neoplastic sheets with less keratinization (hematoxylin and eosin, ×40). (b) Negative Bcl-2 cytoplasmic staining of neoplastic sheets in comparison to positive cytoplasmic staining of surrounding lymphocytes (internal positive control) (Bcl-2, ×40). (c) Weak Bcl-2 cytoplasmic stain; 5–24% positive cells (Bcl-2, ×200).

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Figure 3 Poorly differentiated squamous cell carcinoma. (a) neoplastic sheets with high-degree cellular atypia and no keratin pearls (hematoxylin and eosin, ×100). (b) Strong Bcl-2 cytoplasmic staining of the neoplastic cells (Bcl-2, ×200).

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Low expression of Bcl-2 was observed in one (16.7%) case of well-differentiated OSCC and two (28.6%) cases of moderately differentiated OSCC. On the contrary, poorly differentiated OSCC showed moderate expression (two cases, 28.6%) and strong Bcl-2 expression in one (14.3%) case ([Table 1]).
Table 1 Relation between Bcl-2 expression and tumor histological grade

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Three Bcl-2 low-expression positive cases (50% from total positivity) showed lymph node involvement (N1). Moderate Bcl-2 expression was detected in two (16.66% from total positivity) cases; one of them showed N1 lymph node status, and the other one was N2. On the contrary, Bcl-2 strong expression presented in one case with N2 (16.66% from total positivity). No cases with negative nodal infiltration (N0) showed Bcl-2-positive expression, and only one (100%) case with distant metastasis showed Bcl-2-positive expression. There was a significant correlation between Bcl-2 expression and nodal infiltration, as well as distant metastasis ([Table 2]).
Table 2 Relation between Bcl-2 expression and lymph node metastasis

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Three Bcl-2-positive cases (50% of total positive cases) presented with stage III, two cases with moderate expression (33.33% of total positive cases) presented with stage IV but only one case (16.66% of total positive cases) of stage IV displayed strong expression of Bcl-2. On the contrary, there was no positive expression among cases of stages I or II. There was a significant correlation between clinical stages and Bcl-2 expression ([Table 3]).
Table 3 Relation between Bcl-2 expression and clinicopathologic staging

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  Discussion Top


The present study attempted to throw a beam of light on the possible role of Bcl-2 expression in evaluating OSCC and also its probable prognostic value. The results of this study showed that Bcl-2 oncoprotein is observed as cytoplasmic granular staining, which is in line with the results of Singh et al. (1998), Loro et al. (1999), Chen et al. (2000), and Solomon et al. (2010).

In this study which comprised of 20 cases of OSCC, the total positivity was seen to be 30% (6/20) of all the OSCC cases. In such previous studies, variable results have been shown in relation to Bcl-2 oncoprotein expression in OSCC ranging from 16.67 to 25% by Singh et al. (1998); 30% by Juneja et al. (2015); 36.1% by Piattelli et al. (2002); 50% by Yao et al. (1999); 60% by Jordan et al. (1996); 83.3% by Solomon et al. (2010); and 86.8% by Camisasca et al. (2009).

Variations in Bcl-2 expression patterns could be related to alternate mRNA splicing of the expressed Bcl-2 protein in different tumors. It is known that isoforms of the Bcl-2 protein exist in human tissue and in cell lines. Alternatively, differences in Bcl-2 expression patterns, detectable by Bcl-2 antibodies, could be clarified by elective caspase activation resulting in proteolytic degradation of Bcl-2 in tumor cells. It is worth speculating whether potential isoforms of Bcl-2 or separated variations may influence the sensitivity and specificity of the available Bcl-2 antibodies (Loro et al., 1999).

Bcl-2 expression correlated significantly with cervical lymph node metastasis (P=0.001), indicating association with advanced disease, in accordance with the results reported by Teni et al. (2002) and de Vicente et al. (2006). Our findings differ from those of other studies (Stoll et al., 2000; Lo Muzio et al., 2003). Lo Muzio et al. (2003) found that patients with negative or low Bcl-2 immunoreactivity showed poorer overall survival rates in comparison with patients with high or moderate Bcl-2 immunoreactive tumors; however, this difference was not statistically significant.Stronger expression of Bcl-2 oncoprotein was seen in poorly differentiated OSCC, which is consistent with the findings of Singh et al. (1998), Chen et al. (2000), Sulkowska et al. (2003), and Gulati et al. (2017).

Similar results were seen for TNM staging as positive expression of Bcl-2 was mostly associated with stages III and IV, positive lymph node metastasis, and distant metastasis, which were in agreement with the findings of other researchers (Popovic et al., 2007; Gulati et al., 2017), but in disagreement with others who noted no correlation of TNM staging with Bcl-2 immune expression (Yuen et al., 2002).


  Conclusion Top


Considering the significant correlation between histological differentiation as well as clinical stage and lymph node metastasis with the Bcl-2 expression, Bcl-2 may be used as prognostic factor for OSCC and may aid in decisions on cancer diagnosis and therapy.[29]

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

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