Youji Hu

Expression of a flt-4 (VEGFR3) splicing variant in primary human prostate tumors. VEGF D and flt-4t(Delta773-1081) overexpression is diagnostic for sentinel lymph node metastasis

Utilizing a cDNA expression library established from human prostate PC-3ML tumor cells, we have cloned a truncated flt-4 gene, termed flt-4tΔ773–1081. We have then utilized RNase protection and ELISA to measure the relative levels of VEGF B, C, D and flt-1, KDR, flt-4 and flt-4tΔ773–1081 expression in freshly isolated benign prostatic hyperplasia or BPH tissue (n=21), primary prostate cancers (n=82) and matching sentinel lymph node metastases from stage T2a–T2b/T3 tumors (n=52). Comparisons of the primary tumors with BPH showed that there was a significant upregulation of VEGF-B (P=0.003), VEGF D (P=0.005), flt-1 (P=0.003), KDR (P=0.002), flt-4 (P=0.007), and flt-4tΔ773–1081 (P=0.001), but not VEGF-C (P=0.543). There was no correlation between VEGF-B and its receptor flt-1 (P=0.545), or VEGF-C and flt-4 (P=0.16) and KDR (P=0.23) receptor expression in tumor specimens. Conversely, there was no significant relationship between VEGF-D and the flt-4tΔ773–1081 receptor (P=0.516) expression. Statistical analysis further showed that there was no significant correlation between VEGF-B, VEGF-C, VEGF-D, flt-1, KDR, flt-4 and flt-4tΔ773–1081 with patient age (P>0.10), stage (P>0.10), PSA value (P>0.15) or tumor size (P>0.15). Likewise, there was no significant correlation between VEGF-B, VEGF-C, flt-1, KDR, and flt-4 with Gleason score (P>0.15). In comparison, flt-4tΔ773–1081 levels clearly increased significantly in Gleason score 7 and Gleason score 8–10 tumors as well as in stage T2a–T2b/T3 tumors. The studies were extended to compare gene expression profiles in T2a–T2b and T3 tumors with (n=26) and without (n=26) matching sentinel lymph node metastases. The data showed that VEGF D and flt-4tΔ773–1081 expression levels were significantly elevated in primary tumors with sentinel lymph node involvement compared to those lacking lymph node involvement (P>0.0022 and 0.006, respectively). These data suggest that targeting VEGF D and flt-4tΔ773–1081 receptors may be particularly effective in the prevention of lymph node metastases.

Role of ribosomal protein RPS2 in controlling let-7a expression in human prostate cancer.

We discovered that an inverse relationship exists in the expression of ras/c-myc and ribosomal protein RPS2 with pre-let-7a-1/let-7a/let-7f miRNA and prostate tumor cell malignancy. Nonmalignant IBC-10a cells expressed low levels of ras/RPS2 and elevated pre-let-7a-1/let-7a/let-7f miRNA, whereas the reverse occurred in malignant PCa-20a and PC-3ML cells. Stable transfection of IBC-10a cells with pBABE.ras and pBABE.RPS2 induced ras, c-myc, and RPS2 expression, whereas the levels of let-7a/let-7f miRNA dropped to near zero. Conversely, in pBABE.pre-let-7a-1 transfected PCa-20a and PC-3ML clones, let-7a/let-7f increased whereas ras, RPS2, and c-myc dropped greater than 5-fold. Electrophoretic mobility shift assays, antibody “supershift” assays and immunoprecipitation assays revealed that RPS2 specifically binds pre-let-7a-1 to block RNA processing. Immunoflourescent studies and Northern blots confirmed that RPS2 complexes with pre-let-7a-1 (i.e., in episomal structures) to block processing to let-7a/let-7f, indicating RPS2 may prevent let-7a miRNA expression to indirectly promote oncogene expression. Functional studies further showed that the colony-forming ability (CFA) and invasive activities of IBC-10a cells were significantly enhanced in pBABE-ras.IBC-10a and pBABE-RPS2-IBC-10a clones. Conversely, with the “knockdown” of ras and RPS2 in malignant PC-3ML cells (i.e., in pLKO.TRC.shRNA.ras.PC3-ML, pLKO.TRC.shRNA.RPS2.PC-3ML transfected cells), there was both a loss of these functions and a loss of tumorigenesis in SCID mice. Likewise, with the overexpression of let-7a/let-7f in pBABE.pre-let-7a-1.PC-3ML clones (and PCa-20a clones), CFAs, invasive activities in vitro, and tumorigenesis in vivo were significantly reduced. These results show for the first time that RPS2 blocks pre-let-7a-1 processing to enable ras and c-myc expression and the transformation of primary tumor cells. Mol Cancer Res; 9(1); 36–50 ©2011 AACR.

IL-10/IL-10 Receptor Signaling Regulates TIMP-1 Expression

An IL-10 responsive signal protein, termed IL-10E1, was cloned from human prostate cancer PC-3 ML cells based on its binding affinity for a novel enhancer element (i.e., HTE-1: 5’-CACGATGACTCATCACTGTTGAAAGACA-3’) of the Tissue Inhibitor of metalloproteinase-1 (TIMP-1) gene. Electrophoretic mobility shift assays (EMSAs) and enzyme linked immuno-sandwich assays (ELISAs) showed that IL-10 stimulated the rapid translocation of IL-10E1 to the nucleus and the activation of TIMP-1 expression in 4 different androgen dependent primary prostate tumor lines generated in our laboratory (i.e. HPCA-5a, 5b, 5c and 5d lines). IL-10 signaling was blocked by a variety of agents, including IL-10 receptor antibodies, alpha-toxin, and Genistein. The inhibition of IL-10 signaling and IL-10E1 expression correlated directly with a significant decrease in TIMP-1 expression by the HPCA-5a, 5b, 5c and 5d cell lines. Following permanent transfection of HPCA-5a and 5c cells with the IL-10 gene the growth of tumor xenografts in SCID CB17 mice was severely retarded, yielding tiny, poorly vascularized tumors by ~90 days post-innoculation s.c.. ELISAs showed that these tumors expressed elevated levels of IL-10, IL-10E1 and TIMP-1 compared with tumors from non-transfected or Mock transfected cell lines. We conclude that the IL-10/IL-10 receptor axis (and IL-10E1 signaling) regulation of TIMP-1 expression plays a key role in inhibiting tumor growth, perhaps by blocking tumor vascularization.Key Words: IL-10, IL-10 receptor, Primary human prostate lines, PC-3 ML cells, TIMP-1

Evidence for prostate cancer-associated diagnostic marker-1: immunohistochemistry and in situ hybridization studies.

Purpose: The purpose of this study was to characterize a novel gene/protein associated with prostate cancer, termed prostate cancer-associated diagnostic marker-1 [PCADM-1 (Hu Y, Wang M, Garcia FU, Aoyaki K, Stearns ME. Identification of PCADM-1 as a novel diagnostic marker for prostate cancer, submitted for publication)]. Experimental Design and Results: Immunological studies revealed that rabbit polyclonal antibodies generated against recombinant PCADM-1 specifically recognize the protein in crude protein extracts from a variety of prostate cancer cell lines (i.e., PC-3 ML, LNCaP, DU145, and CPTX-1532) and prostate cancer tissue. Combined immunolabeling and in situ hybridization studies demonstrated that PCADM-1 mRNA was expressed by the luminal epithelial cells of prostate cancer glands and was not expressed by high-grade prostatic intraepithelial neoplasia or HPV-MLC7 cells. Immunolabeling studies of tissue arrays from biopsies of archival material (n = 200 samples) confirmed that PCADM-1 was expressed by the luminal epithelial cells of prostate cancer. Conclusions: Taken together, the data suggest that PCADM-1 is a specific marker for human prostate cancer.

A novel IL-10 signalling mechanism regulates TIMP-1 expression in human prostate tumour cells

We have previously reported that interleukin 10 (IL-10) signalling stimulated activation of a specific enhancer element, termed HTE-1, to promote tissue inhibitor of matrix metalloproteinase1 (TIMP-1) expression in human bone metastatic PC-3 subclone (PC-3 ML) cells. Recently, we have identified an IL-10 responsive signal molecule, termed IL-10E1, which binds the HTE-1 element and cloned the gene encoding for the 22 kDa protein. In this paper, we have examined the mechanism of IL-10/IL-10 receptor signalling in two distinct human prostate cell lines, a ‘normal’ prostate epithelial cell line, termed NPTX-1532 and highly metastatic PC-3 ML tumour cells. Signalling cascade studies revealed that IL-10 stimulated tyrosine phosphorylation of JAK1 and TYK2 receptor kinases and tyrosine phosphorylation of IL-10E1. Phosphorylation, triggered IL-10E1s rapid translocation to the nucleus by 10–30 min. Deletion analysis combined with transient transfection experiments revealed that the n-terminal domain (∼74 a.a.) of the IL-10E1 protein, the nt-nls peptide, was stimulated by IL-10 to translocate to the nucleus and induce TIMP-1 expression. Site-directed mutagenesis further showed that phosphorylation of two tyrosine moieties (Y57 and Y62) of the nt-nls peptide was required for IL-10 activation of signalling and TIMP-1 expression. The data demonstrate, for the first time, that IL-10 receptor signalling of TIMP-1 expression is regulated by tyrosine phosphorylation of a novel gene, IL-10E1, in human prostate cells.

The ABCA5 Protein: A Urine Diagnostic Marker for Prostatic Intraepithelial Neoplasia

Purpose: To develop a urine diagnostic test for preneoplastic intraepithelial neoplasia of the prostate. Experimental Design: We have used a DNA-binding assay and electrophoretic mobility shift assays (EMSA) to screen for novel duplexed DNA-binding sequences, which bind protein(s) overexpressed in crude protein extracts from high-grade prostatic intraepithelial neoplasia (HGPIN). EMSAs, immunohistochemistry, and ELISAs were used to measure expression of the ABCA5 protein identified as a specific marker in prostate tissue and patient urine. Results: Following screening of 4,096 sequences, an 8-bp dsDNA sequence (i.e., TCCAGCGA) was identified, which binds the ABCA5 protein, a member of the ATP-binding cassette multidrug resistant family. EMSAs showed that ABCA5 was overexpressed in HGPIN tissue (n = 11/11) and in the urine of patients with HGPIN (n = 18/18) but was not expressed in prostate cancer, benign prostatic hyperplasia, or stroma. Immunohistochemistry indicated that ABCA5 was overexpressed in foci of intermediate basal cells in normal glands and in HGPIN. ABCA5 was faintly expressed in prostate cancer glands. ELISAs showed in ‘blinded studies’ that ABCA5 was a highly sensitive (>98% sensitivity) urine diagnostic marker for HGPIN in biopsy-positive patients (n = 107) at a ‘cutoff’ of 25 ng/mL. ABCA5 was present at very low levels (i.e., <25 ng/mL) in the urine of patients diagnosed with benign prostatic hyperplasia (n = 79) or prostatitis or kidney and bladder cancer (>86% specificity). Conclusions: The data indicate that ABCA5 might be a specific urine marker for diagnosis of patients with HGPIN.

IL-10 signaling via IL-10E1 is dependent on tyrosine phosphorylation in the IL-10R α chain in human primary prostate cancer cell lines

Interleukin 10 (IL-10) stimulates rapid nuclear translocation and binding of a 22 kDa protein, termed interleukin 10 enhancer 1 (IL-10E1), to a novel enhancer element (i.e. HTE-1) of the tissue inhibitor of metalloproteinase-1 (TIMP-1) gene to upregulate TIMP-1 expression. IL-10E1 signaling involves tyrosine phosphorylation of the IL-10R JAK1 (Janus kinase) and TYK2 (tyrosine kinase) receptor kinases and tyrosine phosphorylation of two tyrosine moieties (Y57 and Y62) of a LIM domain of the IL-10E1 protein. In this paper, the studies showed that two tyrosine residues (Tyr446 and Tyr496) located in the cytoplasmic domain of the IL-10R α chain were required for receptor function, and for phosphorylation and activation of IL-10E1. Immunoprecipitation studies revealed that 12 amino-acid peptides encompassing either of these two tyrosine residues in phosphorylated form coprecipitated IL-10E1 and blocked ligand-dependent IL-10E1 phosphorylation in a cell-free system. In contrast, peptides containing serine substitutions for Tyr446 and Tyr496, and tyrosine-phosphorylated peptides containing Tyr230 or Tyr252/259 did not prevent IL-10E1 activation or signaling. To confirm these observations in vivo, fusion protein constructs were made between a modified form of green fluorescent protein or GFP and the intact IL-10E1 protein (IL-10E1-MmGFP) and n-terminal peptides of the IL-10E1 protein (i.e. nt-nls-MmGFP and mutant sequences identified as nt-nls mC61-MmGFP and nt-nls mY57/mY62-MmGFP peptides). Confocal microscopy revealed that IL-10 triggered transport to the nucleus of IL-10E1-MmGFP, nt-nls-MmGFP, and nt-nls mC61-MmGFP by 10–30 min in HPCA-10a (human prostrate cancer cells; derived from Gleason sum 10 tumor tissue) cells. IL-10 failed to induce nuclear translocation of the mY57/mY62-MmGFP peptides with point mutations of the two tyrosine groups. Coinjection of nt-nls-MmGFP with the IL-10R Tyr446 and Tyr496 amino-acid residues completely blocked ligand signaling. Coinjection of peptides containing either serine substitutions for Tyr446 and Tyr496 or Tyr230 and Tyr252/259 failed to block nt-nls-MmGFP signaling. The data demonstrate that IL-10E1 is directly recruited to the ligand-activated IL-10R by binding to specific phosphotyrosine groups which control tyrosine phosphorylation of the LIM domain of the IL-10E1 protein (i.e. Y57/Y62 groups) and IL-10E1 activation.

Retraction: Role of Ribosomal Protein RPS2 in Controlling let-7a Expression in Human Prostate Cancer

The authors wish to retract the paper entitled Role of Ribosomal Protein RPS2 in Controlling let-7a Expression in Human Prostate Cancer (1), because of errors in Figures 1 and 6.

Reply: TIMP-1 enhancer sequence – real or bacterial?

Sir, The characterisation of the TIMP-1 gene was published in Wang et al (1998). The TIMP-1 gene was cloned from PC-3 ML genomic DNA. The Pst1–Xba1 fragment at the 5′end of the Pst1 4.0-kilobase TIMP-1 genomic clone was subcloned into plasmid PUC 19. This fragment was sequenced from both ends on opposite strands with the Sequenase Virgin 2.0 sequencing system (US Biochemical). Each strand was sequenced with both the Klenow fragment and reverse transcriptase by standard dideoxy procedures. Blast analysis of the 5′ promoter region revealed a 97% homology with Homo sapiens TIMP-1 promoter region (chromosome X genomic contig, NT 011568). Blast analysis of the coding region revealed a 97% homology with human TIMP-1 (Docherty et al, 1985) and 96% homology with the coding region of the E. coli TIMP-1.