[Adaptive immunotherapy of the advanced prostate cancer - cancer testis antigen (CTA) as possible target antigens]. / Adaptive Immuntherapie des fortgeschrittenen Prostatakarzinoms - Cancer Testis Antigene (CTA) als mögliche Zielantigene.

Prostate cancer (PCa) like other tumors expresses antigens that may serve as target for specific immunotherapy. Special antigen-presenting cells (e. g., dendritic cells) are capable of generating tumor-specific immunity. Cytotoxic T-cells (killer cells) are very effective against antigens and, consequently, against the respective tissue or tumor. Cancer testis antigens (CTA) are expressed in various human cancers but, aside from the testicles, not in normal tissue. Therefore, they are suitable for a specific tumor immunotherapy. We looked at different CTA (LAGE-1, PRAME, MAGE-C2, NY-ESO-1, SSX-2 and PAGE4) and their occurrence in prostatic cancer. Expression of CTA in various PCa cell lines and PCa material from patients was very heterogeneous. Only PAGE4 was expressed in primary PCa and in LnCaP cells as well as in hormone-dependent and hormone-refractory PCa probes. We conclude that PAGE4 should be further evaluated as a potential target for immunotherapy of PCa.

The promoter for constitutive expression of the human ICln gene CLNS1A.

The ICln protein is expressed ubiquitously in mammals. Experiments designed to knock down the ICln protein in NIH 3T3 fibroblasts as well as in epithelial cells led to the conclusion that this protein is crucially involved in volume regulation after cytoplasmic swelling. Reconstitution of the ICln protein in lipid bilayers revealed the ion channel nature of ICln. Here we describe a new human promoter sequence, composed of 89 nucleotides, which is responsible for a highly constitutive expression of the ICln protein. The promoter sequence lacks a TATA box, and the transcription can be effected at multiple sites. In addition to the starting sites, upstream sequence elements are mandatory for an efficient transcription of the ICln gene (CLNS1A). These new nucleotide elements were defined by site-directed mutagenesis.

The gastric H,K-ATPase blocker lansoprazole is an inhibitor of chloride channels.

1. It was postulated that swelling dependent chloride channels are involved in the proton secretion of parietal cells. Since omeprazole, lansoprazole and its acid activated sulphenamide form AG2000 are structurally related to phenol derivatives known to block swelling dependent chloride channels, we set out to test, whether these substances--which are known to block the H,K-ATPase--could also lead to an inhibition of swelling-dependent chloride channels. Swelling-dependent chloride channels--characterized in many different cell types--show highly conserved biophysical and pharmacological features, therefore we investigated the effect of omeprazole, lansoprazole and its acid activated sulphenamide form AG2000 on swelling-dependent chloride channels elicited in fibroblasts, after the reduction of the extracellular osmolarity. 2. Omeprazole, lansoprazole and its acid activated sulphenamide form AG2000 are able to block swelling-dependent chloride channels (IClswell). 3. Lansoprazole and its protonated metabolite AG2000 act on at least two different sites of the IClswell protein: on an extracellular site which seems to be in a functional proximity to the nucleotide binding site, and on an intracellular site which allows the formation of disulfide-bridges. 4. The inhibition of the proton pump and the simultaneous blocking of chloride channels by omeprazole, lansoprazole and its acid activated sulphenamide form AG2000, as described here could be an effective mode to restrict proton secretion in parietal cells.

ICln, an ion channel-forming protein associated with cell volume regulation.

It is not resolved whether the anionic channel involved in volume regulation after cell swelling comprises one or more subunits. Moreover, it remains to be determined which of the different proteins cloned so far, for which an involvement in cell volume regulation has been postulated, is the ideal candidate. In this review, we consider the role of the ICln protein, cloned from MDCK cells, in cell volume regulation.

Characterization of the human gene coding for the swelling-dependent chloride channel ICln at position 11q13.5-14.1 (CLNS1A) and further characterization of the chromosome 6 (CLNS1B) localization.

Expression cloning revealed a chloride channel (ICln) that we found to be fundamental for the regulatory volume decrease in a variety of cells. The chromosomal localization of the human ICln-gene showed two loci, one at chromosome 11 in position q13.5-q14.1, termed CLNS1A, and a second one at chromosome 6 at position p12.1-q13, termed CLNS1B. In this study, we offer a detailed characterization of the CLNS1A gene and provide the exact position (6p12) and sequence data of CLNS1B, an intronless gene 91.3% homologous to the coding region of CLNS1A.