Ack1 tyrosine kinase ͉ signal transduction ͉ HER2 ͉ cross-talk

We previously demonstrated that rAAV vectors carrying human and canine factor IX (FIX) cDNA can infect, stably persist, and secrete functional human and canine FIX following direct intramuscular injection. In an attempt to improve FIX protein secretion for eventual therapeutic use, we set out to determine if alteration of the AAV capsid would affect skeletal muscle transduction and factor IX secretion. Two reasons to pursue this question were (1) the persistence of high-titer neutralizing antibody (NAB) to AAV2 and (2) our previous study that supported a restricted tropism of muscle fiber types to AAV2 transduction. Using an identical CMV/canine factor IX (cFIX) expression cassette, we cross-packaged this genome into virions generated from each of the five AAV serotypes. In a dose-response assay, equivalent amounts of rAAV/cFIX serotypes were tested in vitro and in vivo. In tissue culture cells, FIX antigen levels secreted into the supernatant varied depending on the AAV serotype used; type 2 transduced maximally, with serotypes 3, 1, 5, and 4, respectively, expressing lower levels. However, when the same viruses were tested in vivo using immunodeficient NOD/SCID animals, we obtained surprisingly different results. While the time to onset of detectable serum levels appeared the same for all serotypes, types 1, 3, and 5 produced 100- to 1000-fold more cFIX than type 2. In fact, 12 weeks after transduction, type 1 continued to express levels of cFIX on average at 80 microg/ml followed by type 5 (6.52 microg/ml), type 3 (3.27 microg/ml), type 4 (258 ng/ml), and finally type 2 (90 ng/ml). Coagulant activity of cFIX as measured by aPTT supported the circulating levels measured by ELISA demonstrating the secreted protein was functional, and RT-PCR of injected tissue correlated with the serotype-specific transduction data. In summary, we found significant differences in cFIX expression upon introducing various rAAV serotypes into mouse muscle. These data have direct bearing on the design of AAV gene therapy clinical trials for hemophilia and should also extend to most therapeutic transgenes.

Purpose: The androgen receptor (AR) is a liganddependent transcription factor that mediates gene expression and growth of normal and malignant prostate cells. In prostate tumors that recur after androgen withdrawal, the AR is highly expressed and transcriptionally active in the absence of testicular androgens. In these ''androgenindependent'' tumors, alternative means of AR activation have been invoked, including regulation by growth factors and their receptors in prostate cancer recurrence.Experimental Design and Results: In this report, we show that HER receptor tyrosine kinases 1 through 4 are expressed in the CWR-R1 recurrent prostate cancer cell line; their stimulation by epidermal growth factor (EGF) and heregulin activates downstream signaling, including mitogen-activated protein kinase and phosphatidylinositol-3 kinase and Akt pathways. We show that heregulin activates HER2 and HER3 and increases androgen-dependent AR transactivation of reporter genes in CWR-R1 cells. Tyrosine phosphorylation of HER2 and HER3, AR transactivation, and cell proliferation induced by heregulin were more potently inhibited by the EGFR/HER2 dual tyrosine kinase inhibitor GW572016 (lapatinib) than the EGFR-specific inhibitor ZD1839 (gefitinib). Basal proliferation in the absence of growth factors was also inhibited by GW572016 to a greater extent than ZD1839, suggesting that low level HER2/HER3 activation, perhaps by an autocrine pathway contributes to the proliferation signal.Conclusions: These data indicate that heregulin signaling through HER2 and HER3 increases AR transactivation and alters growth in a recurrent prostate cancer cell line. Therefore, inhibition of low-level HER2 signaling may be a potential novel therapeutic strategy in prostate cancer.

CARM1 is essential for AR function and may play a role in prostate cancer progression. CARM1 may represent a novel therapeutic target in prostate cancer.

We previously reported that direct intramuscular injection of non-serotype-2 AAV vectors, especially AAV serotype 1 (AAV1), resulted in expression of supranormal levels of canine F9 in immunodeficient mice. Here we test the ability of the AAV1-F9 vector to deliver sustained expression and correction of factor IX (FIX) deficiency in genetically engineered hemophilic mice. Intramuscular injection of AAV1-F9 resulted in 100-1000 times more canine F9 in plasma of recombinant AAV1-F9 mice compared with injection of AAV2-F9. Assessment of clotting activity by activated partial thromboplastin time confirmed that circulating canine FIX was indeed functional. Moreover, phenotypic correction assayed by tail clip challenge resulted in survival of all AAV1-F9 treated animals, in contrast to naive mice and 50% of AAV2-treated hemophilia B mice, which failed to survive. Administration of cyclophosphamide (CTX) was required to suppress formation of anti-canine FIX antibodies for AAV2-treated animals, whereas it was dispensable for those treated with AAV1-F9. This difference in immunogenicity further emphasizes the usefulness of serotype-specific vectors. Finally, we report that correction of the hemophilia phenotype using AAV1-F9 was complete and persistent (over 8 months), a result that underscores the value of continued exploration of alternative AAV serotype vectors.

Advanced prostate cancer invariably recurs despite androgen deprivation therapy. The androgen receptor (AR) likely plays a key role in this progression and in the continued survival and proliferation of prostate cancer cells in the low androgen environment. Cross-talk with growth factor receptors, such as epidermal growth factor receptor (EGFR) family, has been postulated as a potential mechanism to activate AR in recurrent prostate cancer. We have investigated the role of HER-2/neu (ErbB-2) tyrosine kinase in AR function by characterizing the effect of inhibiting endogenous HER-2 activity in LNCaP cells. We used two independent methods, expression of intracellular single-chain antibody against HER-2 and treatment with a novel dual EGFR/HER-2 kinase inhibitor GW572016 (lapatinib). Expression of intracellular HER-2 antibody scFv-5R and treatment with GW572016 inhibited HER-2 signaling. This HER-2 inhibition led to impairment of AR-mediated functions, such as androgen-stimulated growth and the induction of endogenous prostate-specific antigen (PSA) mRNA and protein. Androgen-stimulated recruitment of AR and histone acetylation at the androgen responsive enhancer of the PSA gene, detected by chromatin immunoprecipitation analysis, were impaired by HER-2 inhibition. GW572016 was more potent in its ability to inhibit PSA expression and AR recruitment and histone acetylation than the EGFR-selective kinase inhibitor ZD1839 (gefitinib), consistent with the HER-2 kinase playing the major role in AR regulation. These results show that HER-2 signaling is required for optimal transcriptional activity of AR in prostate cancer cells and suggest that HER-2 inhibition may provide a novel strategy to disrupt AR function in prostate cancer. (Cancer Res 2005; 65(8): 3404-9)

Allicin is considered anti-atherosclerotic due to its antioxidant and anti-inflammatory effects, which makes it an important drug for the prevention and treatment of atherosclerosis. However, the effects of allicin on foam cells are unclear. Thus, in this study, we examined the effects of allicin on lipid accumulation via peroxisome proliferator-activated receptor γ (PPARγ)/liver X receptor α (LXRα) in THP-1 macrophage-derived foam cells. THP-1 cells were exposed to 100 nM phorbol myristate acetate (PMA) for 24 h, and then to oxydized low-density lipoprotein (ox-LDL; 50 mg/ml) to induce foam cell formation. The results of Oil Red O staining and high-performance liquid chromatography (HPLC) revealed showed that pre-treatment of the foam cells with allicin decreased total cholesterol, free cholesterol (FC) and cholesterol ester levels in cells, and also decreased lipid accumulation. Moreover, allicin upregulated ATP binding cassette transporter A1 (ABCA1) expression and promoted cholesterol efflux. However, these effects were significantly abolished by transfection with siRNA targeting ABCA1. Furthermore, PPARγ/LXRα signaling was activated by allicin treatment. The allicin-induced upregulation of ABCA1 expression was also abolished by PPARγ inhibitor (GW9662) and siRNA or LXRα siRNA co-treatment. Overall, our data demonstrate that the allicin-induced upregulation of ABCA1 promotes cholesterol efflux and reduces lipid accumulation via PPARγ/LXRα signaling in THP-1 macrophage-derived foam cells.

No abstract