Messenger RNA expression of leptin and leptin receptors and their prognostic value in 322 human primary breast cancers.
OBJECTIVE
Leptin and obesity are clearly related, and obesity is associated with an increased risk of breast cancer. We therefore measured the expression of leptin and its two main receptor isoforms, OBR-L and OBR-S, in 322 breast cancers. We analyzed their relations with the classical prognostic factors and with survival to establish their links with breast cancer.


METHODS
The expression of leptin and its receptors was quantified by real-time reverse transcription-PCR, using TaqMan fluorogenic probes and an ABI PRISM 7700 sequence detector system (Applied Biosystems, Courtaboeuf, France). TATA box binding protein was used to normalize expression. The human breast cancer cell, SK-BR-3, expressing the three targets, was chosen as the calibrator sample (i.e., target expression = 1).


RESULTS
All the tumors expressed both receptors, and 318 of 322 expressed leptin. These three variables correlated positively with each other and with estradiol and progesterone receptors, whereas they correlated negatively with histoprognostic grading and tumor diameter. OBR-L/OBR-S expression was inversely correlated with progesterone receptors. Patients with elevated OBR-S expression had longer relapse-free survival (P = 0.008), whereas high OBR-L/OBR-S was associated with a shorter relapse-free survival (P = 0.05). In Cox multivariate analyses, OBR-S maintained its prognostic value (P = 0.02; relative risk, 0.51).


CONCLUSIONS
This study shows that (a) almost all of the breast cancers coexpress leptin and its two main isoforms of receptors, suggesting that the human epithelial breast cancer cells respond to leptin acting via an autocrine pathway; (b) high expression levels of leptin and leptin receptors are biological markers of a more differentiated phenotype; and that (c) OBR-S is an independent prognostic factor.
Révillion
Françoise
F
Laboratoire d'Oncologie Moléculaire Humaine, Département de Sénologie, Laboratoire de Cytologie et d'Anatomie Pathologiques, Centre Oscar Lambret, Lille, France. f-revillion@o-lambret.fr
Charlier
Madia
M
Lhotellier
Valérie
V
Hornez
Louis
L
Giard
Sylvia
S
Baranzelli
Marie-Christine
MC
Djiane
Jean
J
Peyrat
Jean-Philippe
JP
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D020738:Leptin / Q000235:genetics*; D008875:Middle Aged; D015999:Multivariate Analysis; D010641:Phenotype; D011379:Prognosis; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D011956:Receptors, Cell Surface / Q000235:genetics*; D054411:Receptors, Leptin; D012008:Recurrence; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016019:Survival Analysis
C515448:LEPR protein, human; D020738:Leptin; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin