Contained 25 ng cDNA, gene-specific forward and reverse primers for each gene, and 10 mL of 2x Quantitative Sybr Green PCR Master Mix (Applied Biosystems, California, USA). Relative quantification was given by the CT values, determined for triplicate reactions of penile tumor samples and reference samples for each gene and tubulin (TUBA1A) for the endogenous control. The primer sequences are available on request. Therefore, the relative expression of each specific gene was calculated by using the formula: R = (E 
target)DCt target (control sample) /(E endogenous)DCt endogenous (control – sample), as previously described [26]. The cut-off for analysis of gene expression was 4 for increases and decreases in expression. A value below this cutoff was considered to indicate that the increase/decrease in expression was not significant.Table 1. Description of penile squamous cell carcinoma patients with clinical parameters and HPV types.Variable Age years (median 67) #67 .67 T stage T1a,1b, T3,4 N stage N0,1 N2,3 M stage M0 M1 HPV Types None 11 16 16,11 35,11 doi:10.1371/journal.pone.0053260.tNumber of patients2442454724 3 18 1ImmunohistochemistryFor histopathological 842-07-9 web evaluation, two observers that were unaware of the clinical data, reviewed independently the slides, and discrepancies were resolved by joint review of the slides in question. The primary lesion was staged according to the TNM classification system (Americam Joint Committee on Cancer) [18]. Immunohistochemistry was used to evaluate ANXA1 and p16 protein expressions in 20 histologically normal tumor margins (10 margins from squamous cell carcinoma of penis high-risk HPV positive samples and 10 margins from squamous cell carcinoma of penis HPV negative samples – control group), 24 squamous cell carcinoma of penis samples without HPV (HPV-negative group), 3 samples of squamous cell carcinoma of penis samples with low-risk HPVs (HPV-low risk group) and 20 squamous cell carcinoma of penis samples positive for high-risk HPVs (HPV-high risk group) (Table 1). The detection of ANXA1 and p16 were conducted in 4 mm sections of each designated formalin-fixed, paraffin-embedded tissue blocks. After an antigen retrieval step using citrate buffer pH 6.0, the endogenous peroxide activity was blocked and the sections were incubated overnight at 4uC with the primary antibodies: monoclonal anti-p16 (1:1000) (Abcam, Cambridge, UK) or rabbit polyclonal anti-ANXA1 (1:2000) (Zymed Laboratories, Cambridge, UK) diluted 15755315 in 1 BSA. After washing, sections were incubated with a secondary biotinylated 10236-47-2 antibody (Dako, Cambridge, UK). Positive staining was detected using a peroxidase conjugated streptavidin complex and colour developed using DAB substrate (Dako, Cambridge, UK). The sections were counterstained with hematoxylin. The ANXA1 and p16 densitometric analyses were conducted with an Axioskop II microscope (Zeiss, Germany) using the Software AxiovisionTM (Zeiss). For these analyses five different fields from each tumor fragments were used and 20 different points were analyzed for an average related to the intensity of immunoreactivity. The values were obtained as arbitrary units (a.u.).Statistical AnalysisStatistical analysis was performed using GraphPad Prism 6 software (GraphPad, California, USA) and data were expressed as means 6 SEM. The Mann-Whitney U test was used to assess differences in age. The Wilcoxon Signed Ranks Test was applied to compare the gene expression levels in tumor tissue and nor.Contained 25 ng cDNA, gene-specific forward and reverse primers for each gene, and 10 mL of 2x Quantitative Sybr Green PCR Master Mix (Applied Biosystems, California, USA). Relative quantification was given by the CT values, determined for triplicate reactions of penile tumor samples and reference samples for each gene and tubulin (TUBA1A) for the endogenous control. The primer sequences are available on request. Therefore, the relative expression of each specific gene was calculated by using the formula: R = (E target)DCt target (control sample) /(E endogenous)DCt endogenous (control – sample), as previously described [26]. The cut-off for analysis of gene expression was 4 for increases and decreases in expression. A value below this cutoff was considered to indicate that the increase/decrease in expression was not significant.Table 1. Description of penile squamous cell carcinoma patients with clinical parameters and HPV types.Variable Age years (median 67) #67 .67 T stage T1a,1b, T3,4 N stage N0,1 N2,3 M stage M0 M1 HPV Types None 11 16 16,11 35,11 doi:10.1371/journal.pone.0053260.tNumber of patients2442454724 3 18 1ImmunohistochemistryFor histopathological evaluation, two observers that were unaware of the clinical data, reviewed independently the slides, and discrepancies were resolved by joint review of the slides in question. The primary lesion was staged according to the TNM classification system (Americam Joint Committee on Cancer) [18]. Immunohistochemistry was used to evaluate ANXA1 and p16 protein expressions in 20 histologically normal tumor margins (10 margins from squamous cell carcinoma of penis high-risk HPV positive samples and 10 margins from squamous cell carcinoma of penis HPV negative samples – control group), 24 squamous cell carcinoma of penis samples without HPV (HPV-negative group), 3 samples of squamous cell carcinoma of penis samples with low-risk HPVs (HPV-low risk group) and 20 squamous cell carcinoma of penis samples positive for high-risk HPVs (HPV-high risk group) (Table 1). The detection of ANXA1 and p16 were conducted in 4 mm sections of each designated formalin-fixed, paraffin-embedded tissue blocks. After an antigen retrieval step using citrate buffer pH 6.0, the endogenous peroxide activity was blocked and the sections were incubated overnight at 4uC with the primary antibodies: monoclonal anti-p16 (1:1000) (Abcam, Cambridge, UK) or rabbit polyclonal anti-ANXA1 (1:2000) (Zymed Laboratories, Cambridge, UK) diluted 15755315 in 1 BSA. After washing, sections were incubated with a secondary biotinylated antibody (Dako, Cambridge, UK). Positive staining was detected using a peroxidase conjugated streptavidin complex and colour developed using DAB substrate (Dako, Cambridge, UK). The sections were counterstained with hematoxylin. The ANXA1 and p16 densitometric analyses were conducted with an Axioskop II microscope (Zeiss, Germany) using the Software AxiovisionTM (Zeiss). For these analyses five different fields from each tumor fragments were used and 20 different points were analyzed for an average related to the intensity of immunoreactivity. The values were obtained as arbitrary units (a.u.).Statistical AnalysisStatistical analysis was performed using GraphPad Prism 6 
software (GraphPad, California, USA) and data were expressed as means 6 SEM. The Mann-Whitney U test was used to assess differences in age. The Wilcoxon Signed Ranks Test was applied to compare the gene expression levels in tumor tissue and nor.
