P-glycoprotein immunostaining correlates with ER and with high Ki67 expression but fails to predict anthracycline resistance in patients with advanced breast cancer.
In an attempt to further define the clinical utility of p-glycoprotein immunostaining in breast cancer, we examined 101 specimens from patients with advanced breast cancer. There was a significant correlation between estrogen receptor status and p-glycoprotein expression but only for low levels of p-glycoprotein. Premenopausal status appeared to correlate with increased p-glycoprotein expression, but this probably reflects patient selection as premenopausal patients had higher prior exposure to anthracyclines and were more likely to have received chemotherapy as initial treatment. P-glycoprotein expression was highly significantly correlated with expression of the proliferation related antigen Ki67, suggesting that p-glycoprotein expression may well be cell cycle dependent, with overexpression occurring in rapidly cycling cells. These findings may explain reported findings of modulation of p-glycoprotein expression by agents such as anti-oestrogens. P-glycoprotein positive staining did not, however, predict chemotherapy treatment failure or survival duration.
Seymour
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L
Department of Medicine, University of the Witwatersrand, Johannesburg, South Africa.
Bezwoda
W R
WR
Dansey
R D
RD
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000032:analysis*; D000328:Adult; D000903:Antibiotics, Antineoplastic / Q000627:therapeutic use*; D000951:Antigens, Neoplasm / Q000032:analysis*; D001943:Breast Neoplasms / Q000737:chemistry* / Q000188:drug therapy / Q000276:immunology / Q000401:mortality; D018567:Breast Neoplasms, Male / Q000737:chemistry; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D019394:Ki-67 Antigen; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000032:analysis*; D009687:Nuclear Proteins / Q000032:analysis*; D011379:Prognosis; D011960:Receptors, Estrogen / Q000032:analysis*; D015996:Survival Rate; D016896:Treatment Outcome
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D000951:Antigens, Neoplasm; D019394:Ki-67 Antigen; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011960:Receptors, Estrogen