Retinoic acid receptor-beta as a prognostic indicator in stage I non-small-cell lung cancer.
OBJECTIVE
Retinoids are pivotal in the growth and differentiation of certain epithelial tissues, interacting with nuclear retinoid receptors (the retinoic acid receptors [RARs] and retinoid X receptors [RXRs]), which function as transcription factors. RAR-beta mRNA is undetectable by in situ hybridization (ISH) in 50% of non-small-cell lung cancers (NSCLC). RAR-beta may suppress tumorigenicity. Therefore, we hypothesized that loss of expression of RAR-beta gene in stage I NSCLC is a prognostic factor of a poor clinical outcome.


METHODS
We retrospectively analyzed RAR-beta mRNA levels (by ISH using a digoxigenin-labeled antisense riboprobe) in specimens from 185 consecutive patients with completely resected clinical/radiographic stage I NSCLC for whom clinical follow-up data were available.


RESULTS
One hundred fifty-six patients who met the criteria of pathologic stage I NSCLC and positivity for RXR-alpha mRNA (used as a control to assess RNA degradation) and who had adequate follow-up could be evaluated. RAR-beta mRNA expression was undetectable in 51 patients, weakly positive in 64 patients, and strongly positive in 41 patients. Overall survival of the 41 patients with strongly positive RAR-beta was significantly worse than for the 115 patients with weak or absent RAR-beta (P =.045).


CONCLUSIONS
Unexpectedly, strong RAR-beta expression was associated with a significantly worse outcome of early-stage NSCLC. The mechanisms underlying this clinically and biologically important finding should be further explored.
Khuri
F R
FR
Departments of Thoracic/Head and Neck Medical Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA. fkhuri@mdanderson.org
Lotan
R
R
Kemp
B L
BL
Lippman
S M
SM
Wu
H
H
Feng
L
L
Lee
J J
JJ
Cooksley
C S
CS
Parr
B
B
Chang
E
E
Walsh
G L
GL
Lee
J S
JS
Hong
W K
WK
Xu
X C
XC
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis*; D002289:Carcinoma, Non-Small-Cell Lung / Q000737:chemistry* / Q000235:genetics; D018450:Disease Progression; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008175:Lung Neoplasms / Q000737:chemistry* / Q000235:genetics; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D012333:RNA, Messenger / Q000096:biosynthesis; D018168:Receptors, Retinoic Acid / Q000032:analysis* / Q000096:biosynthesis / Q000235:genetics; D012189:Retrospective Studies; D016896:Treatment Outcome
D014408:Biomarkers, Tumor; D012333:RNA, Messenger; D018168:Receptors, Retinoic Acid; C082925:retinoic acid receptor beta