Altered mRNA Expression of NFKB1 and NFKB2 Genes in Penile Lichen Sclerosus, Penile Cancer and Zoon Balanitis

Abstract

Background: The nuclear factor-κB transcription factors 1 and 2 (NFKB1 and NFKB2) are key components of the NF-κB pathway, which responds to inflammatory signals. Since the NFKB1/2 factors are activated via different inflammatory molecules, we aimed to check their expression levels in penile cancer (PC), penile dermatoses: lichen sclerosus (PLS) and zoon balanitis (ZB).

Methods: Skin biopsies from altered and healthy looking foreskin were obtained from 59 (49 LS; early PLS: 13, moderate PLS: 32, severe PLS: 4; 6 PC; 4 ZB) and unchanged foreskin from 13 healthy control adult males undergoing circumcision. NFKB1/2 mRNA levels were quantified by qPCR.

Results: The highest levels of NFKB1 and NFKB2 were observed in PC, ca. 22 and 3.5 times higher than in control, respectively. NFKB1 expression was correlated with PLS progression (rs = 0.667) and was ca. 20 times higher in advanced PLS than in controls and early PLS. Occurrence of micro-incontinence was associated with elevated NFKB1 levels in PLS.

Conclusion: This is the first study regarding gene profiles of NFKB1/2 in PC and penile dermatoses. New drugs targeting modulation of canonical-activated NF-κB pathway should be studied and introduced to the treatment of PLS and PC apart from other treatments.

Keywords: NFKB1/2; penile cancer; penile lichen sclerosus; zoon balanitis.

Figure 1

NFKB1 and NFKB2 gene expression at the mRNA level in penile tissue. Gene expression of (a) NFKB1 and (b) NFKB2 was assessed as described in Methods. Bars and whiskers represent the mean ± SD normalized to control foreskin samples (presented as 1). * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001 (Wilcoxon signed-rank test between inflamed-unchanged samples, dashed line; Mann–Whitney U test between each group, solid line; Kruskal–Wallis ANOVA test between all groups, dotted line). Abbreviations: PLS, penile lichen sclerosus; PC, penile cancer; ZB, zoon balanitis; margin, histologically confirmed healthy fragment of surgically removed foreskin.

Figure 2

Expression of NFKB1 and NFKB2 mRNA in penile lichen sclerosus classified in relation to the severity of disease. (a,c): correlation plots between either NFKB1 or NFKB2 and PLS stages. Solid line: linear regression with 95% confidence interval. (b,d): NFKB1 or NFKB2 mRNA expression levels divided by disease stages: Bars and whiskers represent the mean ± SD normalized to control foreskin samples (presented as 1). * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001 (Mann–Whitney U test between each group, solid line; Kruskal–Wallis ANOVA test between all groups, dotted line). Abbreviation: PLS, penile lichen sclerosus.

Figure 3

NFKB1 and NFKB2 gene expression levels in penile lichen sclerosus related to the occurrence of micro-incontinence. Gene expression levels of (a) NFKB1 or (b) NFKB2 in control or inflamed PLS samples were assessed as described in Methods. Bars and whiskers represent the mean ± SD normalized to control foreskin samples (dotted horizontal line at 1) grouped by each analyzed gene. Bar legends: light-grey bars represent control group (none of them had micro-incontinence), dark-grey bars represent patients with micro-incontinence (MI) while black ones represent patients without MI, respectively. ** p < 0.01, **** p < 0.0001 (Mann–Whitney U test between each group, solid line; Kruskal–Wallis ANOVA test between all groups, dotted line) between MI and lack of MI subgroups. Abbreviation: PLS, penile lichen sclerosus, MI, micro-incontinence.