Over-expression of lysophosphatidic acid receptor-2 in human invasive ductal carcinoma.
BACKGROUND
Lysophosphatidic acid (LPA) is a bioactive phospholipid with diverse effects on various cells. It interacts with at least three G-protein-coupled transmembrane receptors, namely LPA1, LPA2 and LPA3, whose expression in various tumours has not been fully characterized. In the present study we characterized the expression profile of LPA receptors in human breast cancer tissue and assessed the possible roles of each receptor.


METHODS
The relative expression levels of each receptor's mRNA against beta-actin mRNA was examined in surgically resected invasive ductal carcinomas and normal gland tissue using real-time RT-PCR. LPA2 expression was also examined immunohistochemically using a rat anti-LPA2 monoclonal antibody.


RESULTS
In 25 cases normal and cancer tissue contained LPA1 mRNA at similar levels, whereas the expression level of LPA2 mRNA was significantly increased in cancer tissue as compared with its normal counterpart (3479.0 +/- 426.6 versus 1287.3 +/- 466.8; P < 0.05). LPA3 was weakly expressed in both cancer and normal gland tissue. In 48 (57%) out of 84 cases, enhanced expression of LPA2 protein was confirmed in carcinoma cells as compared with normal mammary epithelium by immunohistochemistry. Over-expression of LPA2 was detected in 17 (45%) out of 38 premenopausal women, as compared with 31 (67%) out of 46 postmenopausal women, and the difference was statistically significant (P < 0.05).


CONCLUSIONS
These findings suggest that upregulation of LPA2 may play a role in carcinogenesis, particularly in postmenopausal breast cancer.
Kitayama
Joji
J
Department of Surgical Oncology, The University of Tokyo, Tokyo, Japan. kitayama-1SU@h.u-tokyo.ac.jp
Shida
Dai
D
Sako
Akihiro
A
Ishikawa
Makoto
M
Hama
Kotaro
K
Aoki
Junken
J
Arai
Hiroyuki
H
Nagawa
Hirokazu
H
D000911:Antibodies, Monoclonal / Q000737:chemistry; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D009367:Neoplasm Staging; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D049368:Receptors, Lysophosphatidic Acid / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000911:Antibodies, Monoclonal; D012333:RNA, Messenger; D049368:Receptors, Lysophosphatidic Acid