Abstract
BackgroundHigh mobility group protein box 1 (HMGB1) is a DNA binding protein located in nucleus. It is released into extracellular fluid where it acts as a novel proinflammatory cytokine which interacts with Toll like receptor 4 (TLR4) to activate nuclear factor-κB (NF-κB). This sequence of events is involved in tumor growth and progression. However, the effects of HMGB1, TLR4 and NF-κB on epidermal tumors remain unclear.MethodsHuman epidermal tumor specimens were obtained from 96 patients. Immunohistochemistry was used to detect expression of HMGB1, TLR4 and NF-κB p65 in human epidermal tumor and normal skin specimens. Western blot analysis was used to detect the expression of NF-κB p65 in epithelial cell nuclei in human epidermal tumor and normal tissues.ResultsImmunohistochemistry and western blot analysis indicated a progressive but statistically significant increase in p65 expression in epithelial nuclei in benign seborrheic keratosis (SK), precancerous lesions (PCL), low malignancy basal cell carcinoma (BCC) and high malignancy squamous cell carcinoma (SCC) (P <0.01). The level of extracellular HMGB1 in SK was significantly higher than in normal skin (NS) (P <0.01), and was higher than in SCC but without statistical significance. The level of TLR4 on epithelial membranes of SCC cells was significantly higher than in SK, PCL, BCC and NS (P <0.01). There was a significant positive correlation between p65 expression in the epithelial nuclei and TLR4 expression on the epithelial cell membranes (r = 0.3212, P <0.01).ConclusionsThese findings indicate that inflammation is intensified in parallel with increasing malignancy. They also indicate that the TLR4 signaling pathway, rather than HMGB1, may be the principal mediator of inflammation in high-grade malignant epidermal tumors. Combined detection of p65 in the epithelial nuclei and TLR4 on the epithelial membranes may assist the accurate diagnosis of malignant epidermal tumors.
Highlights
High mobility group protein box 1 (HMGB1) is a DNA binding protein located in nucleus
Expression of Toll like receptor 4 (TLR4) on epithelial cell membranes was significantly higher than in seborrheic keratosis, precancerous lesions, basal cell carcinoma and normal skin (P = 2.3e-5)
Extracellular HMGB1 has been shown to act as a proinflammatory cytokine, which binds to TLR4, TLR2 or receptors for advanced glycation end-products (RAGE) [18,19,20]
Summary
High mobility group protein box 1 (HMGB1) is a DNA binding protein located in nucleus It is released into extracellular fluid where it acts as a novel proinflammatory cytokine which interacts with Toll like receptor 4 (TLR4) to activate nuclear factor-κB (NF-κB). This sequence of events is involved in tumor growth and progression. The most common forms of human epidermal tumors include seborrheic keratosis, precancerous lesions such as Bowen's disease or bowenoid papulosis, and basal or squamous cell carcinoma. Bowenoid papulosis has a histological resemblance to Bowen's disease In this condition atypical keratinocytes are seen at all levels of the
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