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Introduction: Oral squamous cell carcinoma (OSCC) is an aggressive, highly immunosuppressive cancer with a high mortality rate. The interaction between ProgrammedDeath 1 (PD-1) (on T cells) and Programmed-Death Ligand 1 (PD-L1) (on tumour cells) within the tumour microenvironment facilitates T-lymphocytic exhaustion and down-regulation. The tumour thus creates an immunosuppressive network that promotes tumour survival and resists innate immunological defence. Elevated PD-L1 expression has been associated with poor prognosis in various other cancers. Blockage of PD-L1 enhances the immune response in a range of tumour-types. Objectives: To investigate and compare the expression of PD-L1 in non-dysplastic, dysplastic and OSCC samples using immunohistochemistry (IHC). Methods: IHC was performed on formalin-fixed, paraffinembedded, archival tissues. The tissues were divided into three groups; non-dysplastic (n = 20), dysplastic (n = 20) and OSCC (n = 20) tissues. Qualitative and quantitative analyses of positively stained cells were undertaken. One-way analysis of variance (ANOVA) was performed to detect statistically significant differences between PD-L1 expression in the dysplastic and OSCC groups when compared against the non-dysplastic group, which served as a control in this experiment. Results: A higher proportion, darker intensity and a higher immunoreactive score of PD-L1-positive cells was found in the OSCC and dysplastic groups, when compared to the non-dysplastic control group. This difference was statistically significant (p<0.05). There was no significant difference between the OSCC and dysplastic tissues. Conclusion: Greater expression of PD-L1 was correlated to the presence of dysplastic and malignant change. An increase in PD-L1 expression may indicate a disease progression from non-dysplastic tissue to dysplasia and malignancy. [ABSTRACT FROM AUTHOR]

There is a global increase in the prevalence of human papillomavirus (HPV)-driven oropharyngeal squamous cell carcinoma (OPSCC) in Australia and New Zealand. Risk factors for HPV-positive OPSCC are male gender, white race, age older than 40 but younger than 59 years old, having multiple lifetime sex partners, having oro-genital and oro-anal sex. High-risk HPV subtypes play a major role in the pathogenesis of OPSCC, however, they play a much lesser role in oral squamous cell carcinoma (OSCC). Among the laboratory tests used to detect oncogenic HPV infection, polymerase chain reaction is a sensitive method but does not reflect the role of HPV in oncogenesis. While widely used, p16 immunohistochemistry is both a sensitive and a specific surrogate marker for oncogenic HPV infection in OPSCC, but not in OSCC. However, it is a useful prognostic marker in OPSCC. The current gold standard to accurately detect oncogenic HPV infection is E6/E7 mRNAin situ hybridization. Because both HPV-positive and p16-positive OPSCC have better short-term prognoses there is current debate and trials on treatment de-escalation in HPV-positive OPSCC. Dental practitioners can play an important role in early diagnosis of HPV-positive OPSCC. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to investigate the expression of toll-like receptor 2 (TLR2) on cells associated with oral squamous cell carcinoma, epithelial dysplasia and irritative hyperplasia, using immunohistochemistry.Results: More immune cells expressed TLR2 in carcinoma and dysplasia than in hyperplasia (P<0.001). No hyperplastic samples showed positive TLR2 staining on keratinocytes, whereas keratinocytes in 64% of cases of carcinoma and 74% of cases of dysplasia were TLR2 positive.Conclusion: Positive TLR2 expression in the microenvironment suggests activation of immune surveillance against the altered epithelium, whereas TLR2 expression by malignant keratinocytes may be indicative of resistance to apoptosis as a pro-survival mechanism. [ABSTRACT FROM AUTHOR]

The aim of this study is to determine the incidence and frequency of oral maxillofacial tumour reported by Department of Oral Pathology and Oral Medicine, Faculty of Dentistry Universiti Kebangsaan Malaysia (UKM) during the five years period from 1999 to 2003. A total of 226 reports were reviewed. Majority of the specimens reported were sent by the oral surgeons and dental practitioners in the Oral Maxillofacial Unit Hospital Universiti Kebangsaan Malaysia (HUKM), Faculty of Dentistry UKM and Oral Health Division, Kementerian Pertahanan Malaysia. Two hundred and nine diagnosed tissues (87%) were of benign in nature and 17 (7.5%) were malignant. Pyogenic granuloma was the most common lesion with 23 cases (10.2%) reported, followed by squamous cell carcinoma (6.6%), fibroepithelial polyp / fibrous epulis (6.2%), mucous extravasation cyst (6.2%) and ameloblastoma (6.2%). Of the 17 malignancies retrieved, squamous cell carcinoma (n=15) was the most predominant. The relative frequencies of most oral maxillofacial tumour seen in UKM dental faculty are comparative to most similar surveys in the literature particularly with the ones in South East Asia region. Squamous cell carcinoma was ranked 2nd in the series of diagnosed lesion and was the commonest malignancy seen. [ABSTRACT FROM AUTHOR]

Summary: Despite the advances in cancer treatment, the 5-year survival rate for oral cancer has not changed significantly for the past 40years and still remains among the worst of all anatomic sites. Gene expression microarrays have been used successfully in the identification of genetic alterations in cancer development, however, these have hitherto been limited by the need for specimens with good quality intact RNA. Here, we demonstrated the use of formalin-fixed paraffin-embedded tissues in microarray experiments to identify genes differentially expressed between cancerous and normal oral tissues. Forty-three tissue samples were macrodissected and gene expression analyses were conducted using the Illumina DASL assay. We report RNA yield of 2.4 and 0.8μg/mm3 from tumour and normal tissues, respectively and this correlated directly with the tissue volume used for RNA extraction. Using unsupervised hierarchical clustering, distinct gene expression profiles for tumour and normal samples could be generated, and differentially expressed genes could be identified. The majority of these genes were involved in regulation of apoptosis and cell cycle, metastasis and cell adhesion including BCL2A1, BIRC5, MMP1, MMP9 and ITGB4. Representative genes were further validated in independent samples suggesting that these genes may be directly associated with oral cancer development. The ability to conduct microarrays on formalin-fixed paraffin-embedded specimens represents a significant advancement that could open up avenues for finding genes that could be used as prognostication and predictive tools for cancer. [Copyright &y& Elsevier]