6590

SLPI

secretory leukocyte peptidase inhibitor;SLPI;secretory leukocyte peptidase inhibitor

HUSI-1|WAP four-disulfide core domain protein 4|antileukoproteinase|mucus proteinase inhibitor|protease inhibitor WAP4|secretory leukocyte protease inhibitor (antileukoproteinase)|seminal proteinase inhibitor

20q12

protein-coding

Secretory leukocyte protease inhibitor (SLPI) protects tissue from proteases, and promotes cell proliferation and healing during inflammatory response. SLPI is also overexpressed in gastric, lung and ovarian cancers, which accelerates the metastasis of cancer cells. Matrix metalloproteinases-2, -9 (MMP-2 and MMP-9) are overexpressed in high metastatic cancers, and promote the migration of cancer cells through collagen degradation. SLPI and MMP-2, -9 are critical factors in stimulating the metastatic processes but there are no reports of a direct correlation between these molecules. Therefore, this study examined the role of SLPI related to MMP-2 and MMP-9 using two gastric cancer cell lines, such as characterized non-metastatic SNU484 and highly metastatic SNU638 cells. SLPI, MMP-2 and MMP-9 mRNA and protein expression were higher in SNU638 cells than in SNU484 cells. In addition, the rate of cell migration and invasion was higher in the SNU638 cells than in SNU484 cells. Interestingly, after treatment with SLPI, the rate of migration and invasion was higher in the SNU484 cells than in the positive control (PC) SNU484 cells. The rate of migration was also higher in the SNU638 cells after SLPI treatment than in the SNU638 cells (PC) but the invasion rate was not changed. The expression and secretion of MMP-2 and MMP-9 as well the rate of cell migration and invasion were significantly lower in SLPI-siRNA transfected SNU638 cells (si-SLPI/SNU638) but higher in SLPI-treated SNU484 cells (SNU484 + SLPI). Strong Elk-1 phosphorylation was detected in SNU484 + SLPI and SNU638 cells but was barely detectable in SNU484 and si-SLPI/SNU638 cells. These results show that SLPI promotes the metastasis of SNU638 gastric cancer cells by increasing MMP-2 and MMP-9 expression through Elk-1 signaling, indicating its role as a signaling molecule not a protease inhibitor.

Head and neck squamous cell carcinomas (HNSCC) represent the sixth largest group among all human malignancies. However, the exact molecular mechanisms inducing the genesis and the progression of metastasis in these tumors are poorly understood. The identification of molecular alterations involved in metastasis of HNSCC might influence the value of clinical diagnostics, impact therapy strategies and finally improve the prognosis of the patients. The purpose of this study was to identify clinically relevant alterations at the transcriptional and translational levels, when comparing metastatic (N+) and non-metastatic (N0) primary HNSCC. Three transcripts HERPUD1, SLPI and RAD51 were selected for further validation based on their association with carcinogenesis and metastasis. Quantitative real-time-PCR was performed to determine the mRNA expression levels. For subsequent confirmation of the results, immunohistochemistry was performed applying a monoclonal anti-SLPI antibody on 121 HNSCC tumor specimens (N0, n=40; N+, n=81). In metastatic primary cancer, SLPI mRNA showed 5.9-fold lower expression in comparison with non-metastatic primary cancer (p=0.0092). Immunohistochemical staining revealed a fold change of -1.79 between the N+ and the N0 group (p=0.0002). The results presented here clearly indicate the repression of SLPI, measurable on both, mRNA and protein levels in metastatic primary HNSCC as compared to non-metastatic HNSCC. Therefore, it can be assumed that SLPI might have a substantial protective effect on the metastasis process of HNSCC.

BACKGROUND: tumor growth and invasiveness occur through infiltration of tumor cells into the host cells and by angiogenesis, which is modulated by proteinases and antiproteinases released from tumor cells that carry out tissue remodelling. A number of studies have revealed variations in the plasma levels of serine proteases and their inhibitors among tumor types. PATIENTS AND METHODS: By immunological methods we analysed the levels of serine protease inhibitors AAT, ACT and SLPI in newly diagnosed lung cancer patients (n=14) compared to non-smoker and smoker, age- and gender-matched control groups (n=16), and also in an expanded group of lung cancer patients with local tumors (n=14) and with metastasis (n=18). RESULTS: Our data show that plasma levels of AAT, ACT and SLPI were elevated in lung cancer patients by 1.43-fold, p<0.01, 2.57-fold, p<0.01 and 1.6-fold, p<0.001, respectively when compared to controls. In addition, we found that levels of AAT and ACT were higher by 1.47-fold, p<0.001 and 2.27-fold, p<0.001, respectively in lung cancer cases with metastasis compared to localized tumor. CONCLUSION: These inhibitor levels may provide measures of cancer progression in individual patients and possibly offer useful information for an understanding of the mechanisms of metastasis.