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Background: To investigate the possible role of FHIT, a possible tumour suppressor gene, in oral carcinogenesis, we examined 17 oral squamous cell carcinomas (OSCCs) for genetic alterations., Materials and Methods: Fresh tissue was obtained during surgery, snap-frozen in liquid nitrogen and stored at -70 degrees C. Nested PCR amplification to examine the integrity of FHIT mRNA was performed on the reverse transcribed complementary DNA obtained from the frozen normal and tumour tissue. Immunohistochemistry was done on formal in-fixed paraffin-embedded tissue protein from the same cases using a polyclonal antiserum against the full length Fhit., Results: Twelve out 17 (71%) OSCCs showed reduced or absent Fhit protein and half of the cases with reduced Fhit protein exhibited aberrant RT-PCR products., Conclusion: Immunohistochemical detection of Fhit protein expression in OSCCs is the more sensitive method to determine the status of Fhit in these tumours, in agreement with previous studies of other tumour types.

Background: The histogenesis of Warthin's tumour (WT) is controversial. A possible role for Epstein-Barr virus (EBV) has been suggested., Materials and Methods: Twenty formaldehyde-fixed, paraffin-embedded blocks of WT from the parotid gland were examined for the presence of EBV. In situ hybridisation was performed using EBV encoded small nuclear RNAs (EBER1/2) probes labelled with fluorescein isothiocyanate. An EBV-positive P3HR-1 cell line processed to paraffin wax was used as a positive control and a brain section as negative control., Results: EBER1/2 could not be found in the neoplastic epithelial cells in any of the tumours nor in the adjacent normal parotid tissues. Individual positive lymphocytes were present in 7 tumours., Conclusions: These results indicated that EBV is not involved in the pathogenesis of WT.

Background: The prevalence of oral squamous cell carcinoma (OSCC) among the Black community in South Africa is unacceptably high. The association between p53 protein, and PCNA overexpression and the presence of p53 gene mutations was evaluated., Materials and Methods: One hundred and ten formalin-fixed, paraffin-embedded blocks of OSCC were selected for immunohistochemical studies for p53 protein and PCNA expression using the DO-7 and PC10 monoclonal antibodies, respectively. DNA was extracted from fifty-five blocks and exons 5 to 9 of the p53 gene were amplified with nested primers, thereafter sequencing was performed to confirm the presence of mutations detected by single stranded conformational polymorphism., Results: Fifty-six cases (51%) showed p53 expression, while fourteen mutations (25%) were detected. A significant difference was found between the PCNA index in p53 positive and p53 negative tumors while the mean PCNA index for the tumors with p53 mutations was not significantly different from the tumors without mutations., Conclusions: No association between p53 protein overexpression and p53 gene mutations could be demonstrated.

Background: The incidence of oral squamous cell carcinoma (OSCC) is on the increase in developing countries., Materials and Methods: Formalin fixed paraffin embedded blocks of OSCCs from a Black South African population sample of peri-urban and rural origin were selected as follows: Group 1 - 57 OSCCs with a mean age of 59 years; Group 2 - 43 OSCCs all cases younger than 40 years; Group 3 - 46 OSCCs with blocks containing only tumour tissue without any normal epithelium and Group 4, a control group of 38 non-neoplastic epithelial lesions. Type specific primers were used in a standard PCR to amplify a segment of the E6 region of HPV 6, 11, 16 and 18., Results: HPV 11 and 16 DNA were found in one sample each from groups 1 and 2 respectively., Conclusion: HPV is not an etiologic factor in the development of OSCC in the population studied.

Background: Recent studies reported a difference in the age distribution of oral squamous cell carcinoma (OSCC) between Black and White South Africans with OSCC more prevalent in Black patients under the age of 50 compared to Whites., Materials and Methods: Paraffin embedded blocks of OSCC were divided into two groups: one with a mean age of 56.2 years and the second group all younger than 40 years of age. A control group of 30 non-neoplastic intraoral lesions were selected. A standard PCR reaction was used to amplify the BAM H1 W-fragment of the EBV., Results: EBV DNA was demonstrated in 11/45 (24%) cases from the first group and in 11/45 (24%) cases from the second group. EBV DNA was present in 11/30 (37%) cases from the control group., Conclusions: This study showed that the prevalence of EBV in OSCC was not influenced by the age of the patient.