Dihydrotestosterone inhibits arylsulfatase B and Dickkopf Wnt signaling pathway inhibitor (DKK)-3 leading to enhanced Wnt signaling in prostate epithelium in response to stromal Wnt3A

BACKGROUND

In tissue microarrays, immunostaining of the enzyme arylsulfatase B (ARSB; N-acetylgalactosamine-4-sulfatase) was less in recurrent prostate cancers and in cancers with higher Gleason scores. In cultured prostate stem cells, decline in ARSB increased Wnt signaling through effects on Dickkopf Wnt Signaling Pathway Inhibitor (DKK)3. The effects of androgen exposure on ARSB and the impact of decline in ARSB on Wnt signaling in prostate tissue were unknown.

METHODS

Epithelial and stromal tissues from malignant and normal human prostate were obtained by laser capture microdissection. mRNA expression of ARSB, galactose-6-sulfate-sulfatase (GALNS) and Wnt-signaling targets was determined by QPCR. Non-malignant human epithelial and stromal prostate cells were grown in tissue culture, including two-cell layer cultures. ARSB was silenced by specific siRNA, and epithelial cells were treated with stromal spent media following treatment with IWP-2, an inhibitor of Wnt secretion, and by exogenous recombinant human Wnt3A. Promoter methylation was detected using specific DKK3 and ARSB promoter primers. The effects of DHT and of ARSB overexpression on DKK expression were determined. Cell proliferation was assessed by BrdU incorporation.

RESULTS

Normal stroma showed higher expression of vimentin, ARSB, and Wnt3A than epithelium. Normal epithelium had higher expression of E-cadherin, galactose 6-sulfate-sulfatase (GALNS), and DKK3 than stroma. In malignant epithelium, expression of ARSB and DKK3 declined, and expression of GALNS and Wnt signaling targets increased. In cultured prostate epithelial cells, Wnt-mediated signaling was greatest when ARSB was silenced and cells were exposed to exogenous Wnt3A. Exposure to 5α-dihydrotestosterone (DHT) increased ARSB and DKK3 promoter rmethylation, and effects of DHT on DKK3 expression were reversed when ARSB was overexpressed.

CONCLUSIONS

Androgen-induced declines in ARSB and DKK3 may contribute to prostate carcinogenesis by sustained activation of Wnt signaling in prostate epithelium in response to stromal Wnt3A.

Regulation of chondroitin-4-sulfotransferase (CHST11) expression by opposing effects of arylsulfatase B on BMP4 and Wnt9A

In this report, the gene regulatory mechanism by which decline in arylsulfatase B (ARSB; N-acetylgalactosamine-4-sulfatase) reduces CHST11 (chondroitin-4-sulfotransferase; C4ST) mRNA expression in human colonic epithelial cells and in colonic epithelium of ARSB-deficient mice is presented. ARSB controls the degradation of chondroitin 4-sulfate (C4S) by removing the 4-sulfate group at the non-reducing end of the C4S chain, but has not previously been shown to affect C4S biosynthesis. The decline in CHST11 expression following ARSB reduction is attributable to effects of ARSB on bone morphogenetic protein (BMP)4, since BMP4 expression and secretion declined when ARSB was silenced. Inhibition of BMP4 by neutralizing antibody also reduced CHST11 expression. When C4S was more sulfated due to decline in ARSB, more BMP4 was sequestered by C4S in the cell membrane, and CHST11 expression declined. Exogenous recombinant BMP4, acting through a phospho-Smad3 binding site in the CHST11 promoter, increased the mRNA expression of CHST11. In contrast to the decline in BMP4 that followed decline in ARSB, Wnt9A mRNA expression was previously shown to increase when ARSB was silenced and C4S was more highly sulfated. Galectin-3 bound less to the more highly sulfated C4S, leading to increased nuclear translocation and enhanced galectin-3 interaction with Sp1 in the Wnt9A promoter. Silencing Wnt9A increased the expression of CHST11 in the colonic epithelial cells, and chromatin immunoprecipitation assay demonstrated enhancing effects of Wnt9A siRNA and exogenous BMP4 on the CHST11 promoter through the pSmad3 binding site. These findings suggest that cellular processes mediated by differential effects of Wnt9A and BMP4 can result from opposing effects on CHST11 expression.

Mutational analysis of mucopolysaccharidosis type VI patients undergoing a trial of enzyme replacement therapy

Mucopolysaccharidosis type VI (MPS VI), or Maroteaux-Lamy syndrome, is a lysosomal storage disorder caused by a deficiency of N-acetylgalactosamine-4-sulfatase (ARSB). Seven MPS VI patients were chosen for the initial clinical trial of enzyme replacement therapy. Direct sequencing of genomic DNA from these patients was used to identify ARSB mutations. Each individual exon of the ARSB gene was amplified by PCR and subsequently sequenced. Nine substitutions (c.289C>T [p.Q97X], c.629A>G [p.Y210C], c.707T>C [p.L236P], c.936G>T [p.W312C], c.944G>A [p.R315Q], c.962T>C [p.L321P], c.979C>T [p.R327X], c.1151G>A [p.S384N], and c.1450A>G [p.R484G]), two deletions (c.356_358delTAC [p.Y86del] and c.427delG), and one intronic mutation (c.1336+2T>G) were identified. A total of 7 out of the 12 mutations identified were novel (p.Y86del, p.Q97X, p.W312C, p.R327X, c.427delG, p.R484G, and c.1336+2T>G). Two of these novel mutations (p.Y86del and p.W312C) were expressed in Chinese hamster ovary cells and analyzed for residual ARSB activity and mutant ARSB protein. The two common polymorphisms c.1072G>A [p.V358M] and c.1126G>A [p.V376M] were identified among the patients, along with the silent mutation c.1191A>G. Cultured fibroblast ARSB mutant protein and residual activity were determined for each patient, and, together with genotype information, were used to predict the expected clinical severity of each MPS VI patient.

Comparison of fluidized bed and ultrasonic cell-retention systems for high cell density mammalian cell culture

Economically viable biopharmaceutical production is to a high degree dependent on high product yields and stable fermentation systems that are easy to handle. In the current study we have compared two different fermentation systems for the production of recombinant protein from CHO cells. Both systems are fully scaleable and can be used for industrial high cell density bioprocesses. As a model cell line we have used a recombinant CHO cell line producing the enzyme arylsulfatase B (ASB). CHO cells were cultivated as adherent cell culture attached on Cytoline macroporous microcarrier (Amersham Biosciences, Sweden) using a Cytopilot Mini fluidized bed bioreactor (FBR, Vogelbusch-Amersham Biosciences, Austria) and as suspension culture using a stirred tank bioreactor equipped with a BioSep ultrasonic resonator based cell separation device (Applikon, The Netherlands). Both systems are equally well-suited for stable, long-term high cell density perfusion cell culture and provide industrial scalability and high yields. For products such as the recombinant ASB, high perfusion rates and therefore short product bioreactor residence times may be of additional benefit.

Evaluation of fibroblast-mediated gene therapy in a feline model of mucopolysaccharidosis type VI

Fibroblast-mediated ex vivo gene therapy was evaluated in the N-acetylgalactosamine 4-sulfatase (4S) deficient mucopolysaccharidosis type VI (MPS VI) cat. Skin biopsies were obtained at birth from severely affected MPS VI kittens and used to initiate fibroblast outgrowths for retroviral transduction with the 4S cDNA. 4S gene expression in transduced cells was under the transcriptional control of the MoMLV long terminal repeat promoter or the cytomegalovirus (CMV) immediate-early promoter. Characterisation of gene-transduced fibroblasts demonstrated the cells to be over-expressing 4S activity. Twenty-four to forty million autologous, gene-corrected fibroblasts were implanted under the renal capsule of three MPS VI kittens at 8-16 weeks of age. Transient, low levels of 4S activity were detected in peripheral blood leukocytes shortly after implantation but were not detectable within 3-8 weeks' post-implantation. Long-term biochemical and clinical evaluation of these cats demonstrated identical disease progression to that previously described in untreated, clinically severe MPS VI cats.