Down-regulation of trypsinogen-2 expression by chemically modified tetracyclines: association with reduced cancer cell migration.

Many types of human tumor express trypsinogen-2, which may be a significant factor in the activation of pro-MMPs and the invasiveness of tumors. Prevention of trypsinogen-2 expression in cancer cells might be of benefit in cancer therapy. We describe here chemicals capable of down-regulating the expression of trypsinogen-2. Doxycycline (DOXY) and chemically modified tetracyclines (CMTs), previously known as inhibitors of the matrix metalloproteinase (MMP)-dependent proteinase cascade, down-regulated the mRNA and protein expression of trypsinogen-2 by COLO-205 human colon adenocarcinoma cells at therapeutically attainable concentrations (0. 1 to 1.0 microM). DOXY specifically inhibited the activation of pro-MMP-9 and cell migration induced by enteropeptidase, a specific activator of trypsinogen. Pro-MMP-9 activation and cell migration were also inhibited by tumor-associated trypsin inhibitor (TATI), which is a highly specific inhibitor of trypsin. CMT-3 as well as CMT-5 also inhibited cell migration, but an effect on the enteropeptidase-enhanced activation of pro-MMP-9 was not observed. Our results indicate that CMTs, DOXY and TATI inhibit cancer cell migration by down-regulating trypsinogen-2 expression or activity. Inhibition of trypsinogen-2 expression may represent a mechanism contributing to the ability of CMTs to suppress the pericellular proteolytic activity of some tumors.

Tumor-associated trypsin inhibitor in normal and malignant renal tissue and in serum of renal-cell carcinoma patients.

Tumor-associated trypsin inhibitor (TATI) is a 6-kDa peptide, which is identical to the pancreatic-secretory-trypsin inhibitor (PSTI). TATI is produced by several tumors and cancer cell lines, and is used as a serum marker for mucinous ovarian cancer. Elevated serum levels of TATI have also been observed in renal-cell carcinoma (RCC). However, it is unclear whether the increase of serum TATI in this disease is caused by production of TATI by the tumor tissue, by the acute-phase reaction frequently associated with cancer, or by impaired renal function. We examined the expression of TATI in malignant and histologically normal renal tissue by immunohistochemistry, in situ hybridization and reverse-transcriptase-polymerase-chain reaction (RT-PCR). Furthermore, we measured pre-operative serum TATI levels in 21 patients with RCC. Immunohistochemically, TATI was detected in 13 of 20 histologically normal renal-tissue samples, but not in 32 tissue samples from RCC. By RT-PCR, TATI mRNA was detected in all of 10 histologically normal kidneys and in 6 of 11 RCCs, while in situ hybridization analysis gave negative results. Pre-operative serum TATI was elevated in 57% of RCC patients. We also studied expression of TATI mRNA and protein in 7 renal-cancer cell lines, by RT-PCR and immunofluorometric assay respectively: 6 cancer cell lines were positive for TATI mRNA, while 4 of them also produced TATI protein at low levels. These results indicate that TATI is synthesized by the histologically normal renal tissue and by some renal cancers, and suggest that the elevation of serum TATI associated with renal-cell carcinoma may be caused by the release of TATI produced by the tumor.