Aims: Examine expression/mutation of p53, expression of keratins 13, 14 and 19, and presence of HPV in oral squamous cell carcinomas (OSCCs)/potentially-malignant oral lesions from snuff-dippers from Sudan/ non-dippers from Sudan/Scandinavia, and examine expression/mutation of p53, expression of TGF-a, EGFR, c-erbB-2, c-erbB-3, c-erbB-4/PCNA in two series of OSCCs from users of other forms of tobacco from Norway. Methods: Immunohistochemistry, ISH, PCR, nestedPCR/SSCP/DNA sequencing. Results: Levels of expression and mutations of p53 were inconsistent. At the former levels, it was found low in OSCCs from snuff-dippers from Sudan compared with those from non-dippers, but at the later levels, it was found high (exons 5-9) in OSCCs from snuff-dippers, with a novel mutation in exon 6. Keratins were expressed at high levels in OSCCs from snuff-dippers. HPV was absent in Sudanese/Scandinavian OSCCs. High level of expression of p53 was found in the two series of OSCCs from Norway with mutations in exons 5, 7 & 8. High levels of expression of TGF-α, EGFR, c-erbB-2, c-erbB-3, c-erbB-4/PCNA were found. Conclusions: p53 mutations (with probable hot spots for snuff induced OSCCs) may be involved in development of OSCCs in snuff-dippers. Spectrum/profile of mutations found in OSCCs from Sudan/Scandinavia are different. OSCCs lacking negative growth regulation due to inactivation of p53, demonstrate also activation of other proto-oncogenes. Therefore, it is probable that a number of aberrant genetic events are involved in development of OSCCs. Tobacco carcinogens probably affect the mutational hot spots of p53 at certain codons (157, 175, 186, 248, 273, 282) in OSCCs from Scandinavia.
