Expression of the steroid and xenobiotic receptor and its possible target gene, organic anion transporting polypeptide-A, in human breast carcinoma.
Steroid and xenobiotic receptor (SXR) or human pregnane X receptor (hPXR) has been shown to play an important role in the regulation of genes related to xenobiotic detoxification, such as cytochrome P450 3A4 and multidrug resistance gene 1. Cytochrome P450 enzymes, conjugation enzymes, and transporters are all considered to be involved in the resistance of breast carcinoma to chemotherapeutic or endocrine agents. However, the expression of SXR/hPXR proteins and that of its target genes and their biological or clinical significance have not been examined in human breast carcinomas. Therefore, we first examined SXR/hPXR expression in 60 breast carcinomas using immunohistochemistry and quantitative reverse transcription-PCR. We then searched for possible SXR/hPXR target genes using microarray analysis of carcinoma cells captured by laser microscissors. SXR/hPXR was detected in carcinoma tissues but not in nonneoplastic and stromal cells of breast tumors. A significant positive correlation was detected between the SXR/hPXR labeling index and both the histologic grade and the lymph node status of the carcinoma cases. Furthermore, in estrogen receptor-positive cases, SXR/hPXR expression was also positively correlated with expression of the cell proliferation marker, Ki-67. Microarray analysis showed that organic anion transporting polypeptide-A (OATP-A) was most closely correlated with SXR/hPXR gene expression, and both OATP-A mRNA and protein were significantly associated with SXR/hPXR in both breast carcinoma tissues and its cell lines. These results suggest that SXR/hPXR and its target gene, such as OATP-A, may play important roles in the biology of human breast cancers.
Miki
Yasuhiro
Y
Department of Pathology, Tohoku University Graduate School of Medicine, Sendai, Miyagi-ken, Japan.
Suzuki
Takashi
T
Kitada
Kunio
K
Yabuki
Nami
N
Shibuya
Rie
R
Moriya
Takuya
T
Ishida
Takanori
T
Ohuchi
Noriaki
N
Blumberg
Bruce
B
Sasano
Hironobu
H
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis / Q000235:genetics; D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D044584:Carcinoma, Ductal / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D016000:Cluster Analysis; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000235:genetics; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D027361:Organic Anion Transporters / Q000096:biosynthesis* / Q000235:genetics; D000077297:Pregnane X Receptor; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011987:Receptors, Steroid / Q000096:biosynthesis* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D027361:Organic Anion Transporters; D000077297:Pregnane X Receptor; D012333:RNA, Messenger; D011987:Receptors, Steroid; D003577:Cytochrome P-450 Enzyme System; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A