Aquaporin 1 is an independent prognostic factor in pleural malignant mesothelioma.
BACKGROUND
Malignant mesothelioma (MM) is an aggressive cancer of serosal membranes, mostly pleura. It is related to asbestos exposure and its incidence in most industrialized countries is projected to remain stable or to increase until 2020. Prognosis remains poor. Clinical prognostic scoring systems lack precision. No prognostic tissue markers are available. Aquaporin 1 (AQP1) is a cell membrane channel involved in water transport, cell motility, and proliferation. A blocker and an agonist are available.


METHODS
Two independent cohorts of MM were studied. Cohort 1 consisted of 80 consecutive patients who underwent radical surgery (extrapleural pneumonectomy [EPP]). Cohort 2 included 56 conservatively managed patients from another institution. Clinical information was obtained from files. Diagnoses were histologically verified. Immunohistochemical labeling for AQP1 was performed on tumor tissue and the percentage of positive cells was scored.


RESULTS
We demonstrated expression of AQP1 in normal and neoplastic mesothelium at the apical aspect of the cell, in keeping with a role in water transport. For both cohorts, expression of AQP1 by ≥50% of tumor cells was associated with significantly enhanced survival (9.4 months vs 30.4 months in EPP patients and 5 months vs 15 months in conservatively treated patients). This was independent of established prognostic factors, including histologic subtype, pathologic stage, sex, and age at time of diagnosis.


CONCLUSIONS
Expression of AQP1 correlated significantly with prognosis in MM, irrespective of treatment or established prognostic factors. Immunohistochemical labeling for AQP1 should be included in the routine histopathologic workup. An agonist or blocker may become useful for treatment.
Asbestos Diseases Research Institute, Bernie Banton Centre, Rhodes, New South Wales, Australia.
Steven Chuan-Hao
SC
Kao
Nicola
N
Armstrong
Bridget
B
Condon
Kim
K
Griggs
Brian
B
McCaughan
Sarah
S
Maltby
Alan
A
Wilson
Douglas W
DW
Henderson
Sonja
S
Klebe
D000328:Adult; D000368:Aged; D051398:Aquaporin 1 / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008654:Mesothelioma / Q000175:diagnosis*; D016253:Microscopy, Immunoelectron; D008875:Middle Aged; D010997:Pleural Neoplasms / Q000175:diagnosis*; D011379:Prognosis
D014408:Biomarkers, Tumor; D051398:Aquaporin 1