In pulmonary sclerosing hemangioma expression of β-catenin, Axin, and C-myc differs between the two cell types

Previous studies have shown that pulmonary sclerosing hemangioma is a tumor derived from primitive respiratory epithelium, but its character and the differentiation status of the two cell types (polygonal and cuboidal) composing the lesion are still controversial. We hypothesize that the polygonal cells are immature compared with cuboidal cells and have higher proliferative activity. To further study this question, we examined the expression of β-catenin, Axin, and C-myc by immunostaining in 45 primary sclerosing hemangioma (PSH) specimens. The two cell types were captured by laser capture microdissection from 28 PSH specimens, and total RNA was extracted. Messenger RNA (mRNA) expression of Axin and C-myc was examined by reverse transcription polymerase chain reaction (RT-PCR). By immunostaining, β-catenin was predominantly strongly expressed on the cell membrane of cuboidal cells, while in polygonal cells, β-catenin was predominantly expressed in the cytoplasm and significantly decreased on cell membranes. Axin was expressed in cuboidal cells in 93 % of our 45 cases, but only expressed in 18 % of these in polygonal cells. C-myc expression in polygonal cells was significantly stronger than in cuboidal cells (P < 0.05). RT-PCR showed that the expression level of Axin mRNA in cuboidal cells was significantly higher than in polygonal cells (P < 0.05), and expression level of C-myc mRNA in polygonal cells was significantly higher than in cuboidal cells (P < 0.05).The two PHS cell types have distinct expression of β-catenin, Axin, and C-myc, suggesting that their differentiation status may be different. The higher expression of C-myc in polygonal cells suggests that these cells might have higher proliferative activity.