Expression of the nuclear lamins in normal and neoplastic human tissues

Highly specific polyclonal antibodies were raised against synthetic peptides of mammalian A-type nuclear lamins (lamins A and C) and nuclear lamin B. Immunohistochemical techniques were used to examine the expression of these proteins in the nuclear envelopes of both normal and neoplastic human tissues. On sections of normal human tissues, immunohistochemistry revealed differences in the expression of the A-type lamins and constitutive expression of lamin B. Lamins A and C were not detected in rapidly proliferating cells such as the basal keratinocytes of the skin, the crypts of the colon, the germinal centers of lymphoid tissue, the proximal tubules of the kidney, and the germ cells of the testis. Furthermore, lamins A and C were not detected in the nuclei of several terminally differentiated cells, including neurons, glial cells and neuroendocrine cells. Analysis of human tumors showed that lamin B was present in all tumor cell nuclei, whereas in some cases, the A-type lamins were heterogeneously expressed, with some nuclei intensely positive and other nuclei in the same tumor section negative. Immunoblotting of tumor samples was not a sensitive enough technique to detect these variations in A-type lamin expression. These results show that A-type nuclear lamins are expressed in a cell and tissue specific fashion, while lamin B is constitutively expressed. The heterogeneous distribution of the A-type lamins in tumors further suggests that these proteins may be useful as tumor markers or prognostic indicators.