Overexpression of HOXB5, cyclin D1 and PCNA in congenital cystic adenomatoid malformation.

We investigated the patterns of expression of HOXB5, cyclin D1 and proliferating cell nuclear antigen (PCNA) proteins in human congenital cystic adenomatoid malformation (CCAM) to establish the molecular basis of its etiology. Immunohistochemistry was performed on frozen archival specimens of CCAM and normal lung tissue as controls using antibodies against HOXB5, cyclin D1 and PCNA proteins. Immunohistochemistry revealed a higher level of expression of HOXB5, cyclin D1 and PCNA predominantly in mesenchymal cells of the CCAM tissues as compared to normal adjacent control lung tissues. Elevated levels of immunohistochemical detection of HOXB5, cyclin D1 and PCNA were characteristic properties of lung tissue cells in CCAM. This elevated HOXB5 expression may correlate with the aberrant cellular differentiation observed in the CCAM disorder. Elevated expression of cyclin D1 and PCNA further suggests that increased cellular proliferation contributes to the overgrowth of lung tissue in CCAM.