Sirolimus decreases circulating lymphangioleiomyomatosis cells in patients with lymphangioleiomyomatosis.
BACKGROUND
Lymphangioleiomyomatosis (LAM), sporadic or in women with tuberous sclerosis complex (TSC), is characterized by cystic lung destruction, lymphatic involvement (eg, chylous pleural effusions, lymphangioleiomyomas), and renal angiomyolipomas (AMLs). The multisystem manifestations of LAM appear to result from metastatic dissemination of LAM cells bearing inactivating mutations or having loss of heterozygosity (LOH) of the tumor suppressor genes TSC1 or TSC2, which leads to hyperactivation of the mammalian target of rapamycin. Sirolimus slows the decline of lung function, reduces chylous effusions, and shrinks the size of AMLs. The purpose of this study was to determine the effect of sirolimus on circulating LAM cells.


METHODS
Cells from blood were isolated by a density-gradient fractionation system and from urine and chylous effusions by centrifugation. Blood cells were incubated with anti-CD45-fluorescein isothiocyanate (FITC) and anti-CD235a-R-phycoerythrin (PE) antibodies, and urine and chylous effusion cells were incubated with anti-CD44v6-FITC and anti-CD9-R-PE antibodies. Cells were sorted and analyzed for TSC2 LOH.


RESULTS
LAM cells with TSC2 LOH were identified in 100% of blood specimens and 75% of urine samples from patients before therapy. Over a mean duration of 2.2 ± 0.4 years of sirolimus therapy, detection rates of LAM cells were significantly decreased to 25% in blood (P &lt; .001) and 8% in urine (P = .003). Following therapy, a greater loss of circulating LAM cells was seen in postmenopausal patients (P = .025).


CONCLUSIONS
Patients receiving sirolimus had a progressive loss of circulating LAM cells that depended on time of treatment and menopausal status.
Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health.
Xiong
X
Cai
Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health.
Gustavo
G
Pacheco-Rodriguez
Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health.
Mary
M
Haughey
Flow Cytometry Core Facility, National Heart, Lung, and Blood Institute, National Institutes of Health.
Leigh
L
Samsel
Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health.
Suowen
S
Xu
Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health.
Hai-Ping
HP
Wu
Flow Cytometry Core Facility, National Heart, Lung, and Blood Institute, National Institutes of Health.
J Philip
JP
McCoy
Office of Biostatistics Research, Division of Cardiovascular Science, National Heart, Lung, and Blood Institute, National Institutes of Health.
Mario
M
Stylianou
Department of Dermatology, Uniformed Services University of the Health Sciences, Bethesda, MD.
Thomas N
TN
Darling
Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health. Electronic address: mossj@nhlbi.nih.gov.
Joel
J
Moss
D000328:Adult; D000903:Antibiotics, Antineoplastic / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019656:Loss of Heterozygosity; D018192:Lymphangioleiomyomatosis / Q000097:blood / Q000188:drug therapy* / Q000235:genetics; D008875:Middle Aged; D009360:Neoplastic Cells, Circulating; D020123:Sirolimus / Q000627:therapeutic use*; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins / Q000235:genetics
D000903:Antibiotics, Antineoplastic; C000624653:TSC2 protein, human; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; D020123:Sirolimus