Inhibition of specific matrix metalloproteinases (MMP) is an attractive noncytotoxic approach to cancer therapy.

cAMP‐dependent protein kinase (A‐kinase) anchoring proteins (AKAPs) are responsible for the subcellular sequestration of the type II A‐kinase. Previously, we identified a 78 kDa AKAP which was enriched in gastric parietal cells. We have now purified the 78 kDa AKAP to homogeneity from gastric fundic mucosal supernates using type II A‐kinase regulatory subunit (RII) affinity chromatography. The purified 78 kDa AKAP was recognized by monoclonal antibodies against ezrin, the canalicular actin‐associated protein. Recombinant ezrin produced in either Sf9 cells or bacteria also bound RII. Recombinant radixin and moesin, ezrin‐related proteins, also bound RII in blot overlay. Analysis of recombinant truncations of ezrin mapped the RII binding site to a region between amino acids 373 and 439. This region contained a 14‐amino‐acid amphipathic α‐helical putative RII binding region. A synthetic peptide containing the amphipathic helical region (ezrin409–438) blocked RII binding to ezrin, but a peptide with a leucine to proline substitution at amino acid 421 failed to inhibit RII binding. In mouse fundic mucosa, RIIimmunoreactivity redistributed from a predominantly cytosolic location in resting parietal cells, to a canalicular pattern in mucosa from animals stimulated with gastrin. These results demonstrate that ezrin is a major AKAP in gastric parietal cells and may function to tether type II A‐kinase to a region near the secretory canaliculus.

Protein kinase A-anchoring proteins (AKAPs) localize the second messenger response to particular subcellular domains by sequestration of the type II protein kinase A. Previously, AKAP120 was identified from a rabbit gastric parietal cell cDNA library; however, a monoclonal antibody raised against AKAP120 labeled a 350-kDa band in Western blots of parietal cell cytosol. Recloning has now revealed that AKAP120 is a segment of a larger protein, AKAP350. We have now obtained a complete sequence of human gastric AKAP350 as well as partial cDNA sequences from human lung and rabbit parietal cells. The genomic region containing AKAP350 is found on chromosome 7q21 and is multiply spliced, producing at least three distinct AKAP350 isoforms as well as yotiao, a protein associated with the N-methyl-D-aspartate receptor. Rabbit parietal cell AKAP350 is missing a sequence corresponding to a single exon in the middle of the molecule located just after the yotiao homology region. Two carboxyl-terminal splice variants were also identified. Both of the major splice variants showed tissue-and cell-specific expression patterns. Immunofluorescence microscopy demonstrated that AKAP350 was associated with centrosomes in many cell types. In polarized Madin-Darby canine kidney cells, AKAP350 localized asymmetrically to one pole of the centrosome, and nocodazole did not alter its localization. During the cell cycle, AKAP350 was associated with the centrosomes as well as with the cleavage furrow during anaphase and telophase. Several epithelial cell types also demonstrated noncentrosomal pools of AKAP350, especially parietal cells, which contained multiple cytosolic immunoreactive foci throughout the cells. The localization of AKAP350 suggests that it may regulate centrosomal and noncentrosomal cytoskeletal systems in many different cell types.Transduction of signals from extracellular stimuli is most commonly accomplished via ligand-receptor binding and generation of a second messenger response. While increases in intracellular second messengers have traditionally been viewed as global cellular events, second messenger effects are often limited to particular regions or organelles within cells. Investigations over the past decade have led to a greater understanding of the mechanisms responsible for the compartmentalization of second messenger effects. These studies have identified a diverse group of scaffolding proteins that sequester both protein kinases and protein phosphatases within specific cellular domains (1, 2). In the case of cAMP-dependent protein kinases, protein kinase A-anchoring proteins (AKAPs) 1 tether the protein kinase A holoenzyme through binding to the regulatory subunit dimer. A growing group of AKAPs that bind the regulatory subunit of type II protein kinase A (R II ) have been reported over the past several years. The first R II -binding protein was identified over 15 years ago when microtubule-associated protein 2 (MAP-2) was described (3, 4). Since that time, several AKAPs have been identified, localizing the type...

MMP14 blockade decreased immunosuppressive TGFβ, polarized macrophages to an antitumor phenotype, increased iNOS, and improved tumor perfusion, resulting in reduced primary tumor growth and enhanced response to radiation therapy, especially in high MMP14-expressing tumors.