UCHL1 is a potential molecular indicator and therapeutic target for neuroendocrine carcinomas.

Neuroendocrine carcinomas, such as neuroendocrine prostate cancer and small-cell lung cancer, commonly have a poor prognosis and limited therapeutic options. We report that ubiquitin carboxy-terminal hydrolase L1 (UCHL1), a deubiquitinating enzyme, is elevated in tissues and plasma from patients with neuroendocrine carcinomas. Loss of UCHL1 decreases tumor growth and inhibits metastasis of these malignancies. UCHL1 maintains neuroendocrine differentiation and promotes cancer progression by regulating nucleoporin, POM121, and p53. UCHL1 binds, deubiquitinates, and stabilizes POM121 to regulate POM121-associated nuclear transport of E2F1 and c-MYC. Treatment with the UCHL1 inhibitor LDN-57444 slows tumor growth and metastasis across neuroendocrine carcinomas. The combination of UCHL1 inhibitors with cisplatin, the standard of care used for neuroendocrine carcinomas, significantly delays tumor growth in pre-clinical settings. Our study reveals mechanisms of UCHL1 function in regulating the progression of neuroendocrine carcinomas and identifies UCHL1 as a therapeutic target and potential molecular indicator for diagnosing and monitoring treatment responses in these malignancies.

Brefeldin a induces apoptosis by activating the mitochondrial and death receptor pathways and inhibits focal adhesion kinase-mediated cell invasion.

Brefeldin A induces apoptosis in various cancer cells; however, the apoptotic process in cancer cells exposed to brefeldin A remains unclear. In addition, it is unclear whether brefeldin A-induced apoptosis is mediated by the formation of reactive oxygen species. Furthermore, the effect of brefeldin A on the invasion and migration of human epithelial ovarian cancer cells has not been studied. Therefore, we investigated the effect of brefeldin A on apoptosis, cell adhesion and migration using the human epithelial ovarian carcinoma cell lines OVCAR-3 and SK-OV-3. The results suggest that brefeldin A may induce apoptotic cell death in ovarian carcinoma cell lines by activating the mitochondrial pathway and the caspase-8- and Bid-dependent pathways. The apoptotic effect of brefeldin A seems to be mediated by formation of reactive oxygen species and depletion of GSH, which results in the activation of apoptotic caspases. Brefeldin A inhibited foetal bovine serum-induced adhesion and migration of OVCAR-3 cells. Brefeldin A may prevent the foetal bovine serum-induced cell adhesion and migration by limiting the focal adhesion kinase-dependent activation of cytoskeletal-associated components.

Combined effect of Hsp90 inhibitor geldanamycin and parthenolide via reactive oxygen species-mediated apoptotic process on epithelial ovarian cancer cells.

Hsp90 inhibitor geldanamycin and parthenolide have been shown to induce apoptosis in cancer cells. However, the combined effect of geldanamycin and parthenolide on epithelial ovarian cancer cells has not been studied. In respect of cell death process, we investigated the promoting effect of parthenolide on geldanamycin-induced apoptosis in the human epithelial ovarian carcinoma cell lines OVCAR-3 and SK-OV-3. Geldanamycin induced a decrease in Bid, Bcl-2, Bcl-xL and survivin protein levels; an increase in Bax and tumour suppressor p53 levels; loss of the mitochondrial transmembrane potential; cytochrome c release; activation of caspases (-8, -9 and -3); cleavage of PARP-1; and increase in the reactive oxygen species formation. Parthenolide enhanced geldanamycin-induced changes in the apoptosis-related protein levels, reactive oxygen species formation, nuclear damage and cell death. The combined effect was inhibited by the addition of oxidant scavengers. The results suggest that parthenolide may potentiate the apoptotic effect of geldanamycin on ovarian carcinoma cell lines by the activation of the caspase-8- and Bid-dependent pathway and the mitochondria-mediated apoptotic pathway. The apoptosis-promoting effect seems to be mediated by the stimulatory effect on the formation of reactive oxygen species.

Guanylate cyclase activator YC-1 enhances TRAIL-induced apoptosis in human epithelial ovarian carcinoma cells via activation of apoptosis-related proteins.

To assess the ability of 3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole (YC-1) to promote apoptosis, we investigated the effect of YC-1 on tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in the human epithelial ovarian carcinoma cell lines. In OVCAR-3 and SK-OV-3 cell lines, we examined the stimulatory effect of YC-1 on TRAIL-induced apoptosis by monitoring cell death, nuclear damage, changes in apoptosis-related protein levels, activation of caspases and changes in the mitochondrial transmembrane potential. TRAIL induced a decrease in Bid, Bcl-2 and Bcl-xL protein levels, increase in cleaved Bid and Bax levels, loss of the mitochondrial transmembrane potential, cytochrome c release, activation of caspases (-8, -9 and -3) and an increase in the tumour suppressor p53 levels. YC-1 enhanced TRAIL-induced apoptosis-related protein activation, nuclear damage and cell death. Results from this study suggest that YC-1 may enhance the apoptotic effect of TRAIL on ovarian carcinoma cell lines by increasing the activation of the caspase-8- and Bid-dependent pathways and the mitochondria-mediated apoptotic pathway, leading to caspase activation. YC-1 may confer a benefit in TRAIL treatment of epithelial ovarian adenocarcinoma.

Antiplasmin-cleaving enzyme is a soluble form of fibroblast activation protein.

Circulating antiplasmin-cleaving enzyme (APCE) has a role in fibrinolysis and appears structurally similar to fibroblast activation protein (FAP), a cell-surface proteinase that promotes invasiveness of certain epithelial cancers. To explore this potential relationship, we performed comparative structure/function analyses of the 2 enzymes. APCE from human plasma and recombinant FAP (rFAP) exhibited identical pH optima of 7.5, extinction coefficients (in(280 nm)(1%)) of 20.2 and 20.5, common sequences of tryptic peptides, and cross-reactivity with FAP antibody. APCE and rFAP are homodimers with monomeric subunits of 97 and 93 kDa. Only homodimers appear to have enzymatic activity, with essentially identical kinetics toward Met-alpha2-antiplasmin (Met-alpha2AP) and peptide substrates. APCE and rFAP cleave both Pro3-Leu4 and Pro12-Asn13 bonds of Met-alpha2AP, but relative kcat/Km values for Pro12-Asn13 are about 16-fold higher than for Pro3-Leu4. APCE and rFAP demonstrate higher kcat/Km values toward a peptide modeled on P4-P4' sequence surrounding the Pro12-Asn13 primary cleavage site than for Z-Gly-Pro-AMC and Ala-Pro-AFC substrates. These data support APCE as a soluble derivative of FAP and Met-alpha2AP as its physiologic substrate. Conversion of Met-alpha2AP by membrane or soluble FAP to the more easily fibrin-incorporable form, Asn-alpha2AP, may increase plasmin inhibition within fibrin surrounding certain neoplasms and have an impact on growth and therapeutic susceptibility.