[Immunoelectron microscopic analysis of P-glycoprotein, p53, and Bcl-2 proteins expressions in lung cancer].
OBJECTIVE
To determine the ultrastructural localization of P-gp, p53 protein, and Bcl-2 protein in lung cancer cells, their relation to multidrug resistance and possible mechanisms of action.


METHODS
Expression of P-gp, p53, and Bcl-2 proteins was examined in 8 NSCLC surgical specimens and 7 SCLC bronchoscopically biopsied specimens using postembedding PAG immunolabelling technique for electron microscopy.


RESULTS
P-gp was detected on the cell membrane and the periphery of endoplasmic reticulum (ER). P53 protein was observed not only in the nuclei associated with heterochromatin but also in the cytosol. Bcl-2 protein immunoreactivity was associated with mitochondria and ER. P-gp, p53, and Bcl-2 were detected in 5(33%), 9(60%), and 4 (26.7%) out of the 15 samples examined, respectively. In 8 normal lung tissues, these three proteins were detected. Of 5 P-gp positive samples 4 were NSCLC, only 1 was SCLC after chemotherapy.


CONCLUSIONS
P-gp, p53, and Bcl-2 proteins are detectable immuno-electron microscopically in lung cancer cells. No correlation in expression existed between of p53 and P-gp, nor did that between p53 and Bcl-2. The plasma membrane localization of P-gp supports its action as a transmembrane drug efflux pump. P-gp may play a role in MDR in lung cancer.
Huang
X
X
Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China.
Li
L
L
Guo
Z
Z
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis*; D002289:Carcinoma, Non-Small-Cell Lung / Q000378:metabolism*; D018288:Carcinoma, Small Cell / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006570:Heterochromatin / Q000378:metabolism; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism*; D016253:Microscopy, Immunoelectron / Q000379:methods; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis*; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis*
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D006570:Heterochromatin; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53