It was previously shown that protein and mRNA expression of the antileukoproteinase SLPI was significantly inverse correlated with HPV-infection in HNSCC and led to the suggestion that elevated expression of SLPI protects against HPV-infection in HNSCC. In addition we could show that SLPI expression was upregulated in HNSCC patients reporting a smoking habit. Here we investigate whether this inverse correlation between HPV-infection smoking habit and SLPI expression could also be found in other HPV-driven cancers, namely vulvar squamous cell carcinoma (VSCC).
FFPE samples of 116 VSCC were analyzed by PCR and RT-qPCR for HPV-DNA-, and SLPI mRNA-expression and data were correlated. Data correlating HPV- and SLPI-expression with smoking habit are so far preliminary since at present only 68 patients files are complete. The same holds true for Kaplan-Meyer-analysis correlating HPV-status and SLPI-expression with overall (OS) and progression free survival (PFS).
Of the analyzed 116 VSCC 10 (8.6%) are HPV-DNA positive (Genotyping by Sanger sequencing is ongoing, followed by HPV-RNA-analysis). Of the 68 patients with complete files 24 (35.3%) reported a smoking habit and of these patients 3 (12.5%) were HPV-positive. So far 3 further HPV-positive patients were identified as non-smokers and for the remaining 4 at present no data are available. SLPI-expression however, was independent of the smoking habit, 4.0-fold lower in HPV-positive than HPV-negative patients. Smoking on the other hand resulted, independent of the HPV-status of the patients, in 5.6-fold higher SLPI expression. HPV-positivity and low SLPI-expression are associated with better PSF (analysis of OS data is ongoing).
The data presented here indicate that SLPI plays a pivotal role in HPV-infection not only in HNSCC but also in VSCC and possibly also in other HPV-driven cancers. This however, needs to be analyzed in future studies. Furthermore these data lead to the hypothesis that the smoking induced SLPI-increase is systemic rather than local, as assumed based on the HNSCC data.