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PDF file 79K, GAG-HERV-K ch22q11.23 features. Endogenous retrovirus K from chromosome 22 is located on the q11.23 region, nearby the BCR, ZDHHC8P, IGLL1 and RGL4 genes. HERV-K ch22q11.23 has GAG-PRO, POL and ENV genes flanked by LTR sequences. The GAG gene has an ORF encoding a 715aa protein that contains P10, P24 and Zinc finger domains. {delta}: deletions; I: early stop codons; --> primer binding regions; ABS: antibody binding site for monoclonal antibody TI-35 (see Supplementary Fig. S3C)

PDF file 204K, Alignment of GAG proteins derived from human endogenous retroviruses and respective epitopes recognized by prostate cancer patient sera. A, Detail alignment from several GAG-HERV-K family members and the TI-35 binding site (red) highlighting the amino-acid differences present in GAG-HERV-K ch22q11.23 (blue). B, Western-blot analysis of immunoprecipitation of GAG-HERV-K from VCaP and LNCaP prostate cancer cell lines. WFP prostate cancer patient serum (WFP) was incubated with VCaP or LNCaP protein extract for 2 hours at 4{degrees}C. Protein-antibody complexes were pulled down using anti-human IgG sepharose beads. The pull-down pellet was submitted to SDS-PAGE and Western-blot analysis. Reactivity to GAG-HERV-K protein was developed by incubating the membrane with TI-35 monoclonal antibody. A pool of healthy donor sera was used as control (Con). C, Summary of ELISA results from epitope mapping using 20mers peptides overlapping by 10aa (71 peptides tested in total from JPT Innovative Peptide Solution, Berlin, Germany) spanning GAG-HERV-K and tested individually for recognition by monoclonal antibody TI-35 and different prostate cancer patient sera seropositive for GAG-HERV-K protein. The square symbol represents a positive reaction to the corresponding peptide (labeled by aminoacid start and end position). A pool of healthy donor sera was used as control (Con pool). Plates were coated with 5 uM peptide and the reaction was performed as previously described in methods

PDF file 90K, Supplementary Figure Legends

Purpose: Human endogenous retroviruses (HERV) encode 8% of the human genome. While HERVs may play a role in autoimmune and neoplastic disease, no mechanistic association has yet been established. We studied the expression and immunogenicity of a HERV-K GAG protein encoded on chromosome 22q11.23 in relation to the clinical course of prostate cancer.Experimental Design:In vitro expression of GAG-HERV-K was analyzed in panels of normal and malignant tissues, microarrays, and cell lines, and effects of demethylation and androgen stimulation were evaluated. Patient sera were analyzed for seroreactivity to GAG-HERV-K and other self-antigens by ELISA and seromics (protein array profiling).Results: GAG-HERV-K expression was most frequent in prostate tissues and regulated both by demethylation of the promoter region and by androgen stimulation. Serum screening revealed that antibodies to GAG-HERV-K are found in a subset of patients with prostate cancer (33 of 483, 6.8%) but rarely in male healthy donors (1 of 55, 1.8%). Autoantibodies to GAG-HERV-K occurred more frequently in patients with advanced prostate cancer (29 of 191 in stage III–IV, 21.0%) than in early prostate cancer (4 of 292 in stages I–II, 1.4%). Presence of GAG-HERV-K serum antibody was correlated with worse survival of patients with prostate cancer, with a trend for faster biochemical recurrence in patients with antibodies to GAG-HERV-K.Conclusions: Preferential expression of GAG-HERV-K ch22q11.23 in prostate cancer tissue and increased frequency of autoantibodies observed in patients with advanced prostate cancer make this protein one of the first bona fide retroviral cancer antigens in humans, with potential as a biomarker for progression and biochemical recurrence rate of prostate cancer. Clin Cancer Res; 19(22); 6112–25. ©2013 AACR.

PDF file 63K, Correlation between antibodies against GAG-HERV-K and group risk or Gleason score in cancer patients. Prostate cancer patients were split (A) in 3 groups according to Gleason score and classified from group risk 1 to 3 and compared to healthy donors (HD), or (B) in 3 groups according to Gleason score as indicated. Antibodies anti-GAG-HERV-K were detected and analyzed as in Fig. 4. Asterisk denotes significantly higher frequency of seropositive patients (titer > 100) in risk group 3 and Gleason {greater than or equal to} 8 (Chi-square test, p

PDF file 341K, qPCR gene expression analysis of chromosome 22q11.23 region in cancer tissues. Total RNA from cancer tissues was submitted to DNAse treatment and reverse transcriptase reaction for cDNA synthesis. The resulting cDNA was used on qPCR to detect the expression of GAG-HERV-K and the neighbor genes BCR, IGGL1, RGL4 and ZDHHC8P. The results are expressed as relative expression to GAG-HERV-K levels in normal prostate. GAG-HERV-K expression is relative to GAPDH. BCR, IGGL1, RGL4 and ZDHHC8P expression is relative to TFRC

Purpose: Human endogenous retroviruses (HERV) encode 8% of the human genome. While HERVs may play a role in autoimmune and neoplastic disease, no mechanistic association has yet been established. We studied the expression and immunogenicity of a HERV-K GAG protein encoded on chromosome 22q11.23 in relation to the clinical course of prostate cancer. Experimental Design: In vitro expression of GAG-HERV-K was analyzed in panels of normal and malignant tissues, microarrays, and cell lines, and effects of demethylation and androgen stimulation were evaluated. Patient sera were analyzed for seroreactivity to GAG-HERV-K and other self-antigens by ELISA and seromics (protein array profiling). Results: GAG-HERV-K expression was most frequent in prostate tissues and regulated both by demethylation of the promoter region and by androgen stimulation. Serum screening revealed that antibodies to GAG-HERV-K are found in a subset of patients with prostate cancer (33 of 483, 6.8%) but rarely in male healthy donors (1 of 55, 1.8%). Autoantibodies to GAG-HERV-K occurred more frequently in patients with advanced prostate cancer (29 of 191 in stage III–IV, 21.0%) than in early prostate cancer (4 of 292 in stages I–II, 1.4%). Presence of GAG-HERV-K serum antibody was correlated with worse survival of patients with prostate cancer, with a trend for faster biochemical recurrence in patients with antibodies to GAG-HERV-K. Conclusions: Preferential expression of GAG-HERV-K ch22q11.23 in prostate cancer tissue and increased frequency of autoantibodies observed in patients with advanced prostate cancer make this protein one of the first bona fide retroviral cancer antigens in humans, with potential as a biomarker for progression and biochemical recurrence rate of prostate cancer. Clin Cancer Res; 19(22); 6112–25. ©2013 AACR.