A robust assay for alternative lengthening of telomeres in tumors shows the significance of alternative lengthening of telomeres in sarcomas and astrocytomas.
OBJECTIVE
Telomeres of tumor cells may be maintained by telomerase or by alternative lengthening of telomeres (ALT). The standard ALT assay requires Southern analysis of high molecular weight genomic DNA. We aimed to establish and validate an ALT assay suitable for archived paraffin-embedded tumors and to use it to examine the prevalence and clinical significance of ALT in various types of tumors that are often telomerase negative.


RESULTS
To assay for ALT, we detected ALT-associated promyelocytic leukemia (PML) bodies (APBs) by combined PML immunofluorescence and telomere fluorescence in situ hybridization. APBs are PML nuclear domains containing telomeric DNA and are a known hallmark of ALT in cell lines. The APB assay concurred with the standard ALT assay in 62 of 62 tumors and showed that 35% of 101 soft tissue sarcomas (STS), 47% of 58 osteosarcomas (especially younger patients), 34% of 50 astrocytomas, and 0% of 17 papillary thyroid carcinomas were ALT positive (ALT+). The prevalence of ALT varied greatly among different STS subtypes: malignant fibrous histiocytomas, 77%; leiomyosarcomas, 62%; liposarcomas, 33%; synovial sarcomas, 9%; and rhabdomyosarcomas, 6%. ALT correlated with survival in glioblastoma multiforme and occurred more often in lower-grade astrocytomas, but ALT+ and ALT- sarcomas were equally aggressive in terms of grade and clinical outcome.


CONCLUSIONS
The APB assay for ALT is suitable for paraffin-embedded tumors. It showed that a substantial proportion of STS, osteosarcomas, and astrocytomas, but not papillary thyroid carcinomas use ALT. APB positivity correlated strongly with survival of patients with astrocytomas.
Henson
Jeremy D
JD
Children's Medical Research Institute, New South Wales, Australia.
Hannay
Jonathan A
JA
McCarthy
Stanley W
SW
Royds
Janice A
JA
Yeager
Thomas R
TR
Robinson
Robert A
RA
Wharton
Stephen B
SB
Jellinek
David A
DA
Arbuckle
Susan M
SM
Yoo
Jinyoung
J
Robinson
Bruce G
BG
Learoyd
Diana L
DL
Stalley
Paul D
PD
Bonar
S Fiona
SF
Yu
Dihua
D
Pollock
Raphael E
RE
Reddel
Roger R
RR
D000328:Adult; D000368:Aged; D017209:Apoptosis; D001254:Astrocytoma / Q000235:genetics / Q000378:metabolism*; D015139:Blotting, Southern / Q000379:methods; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D016922:Cellular Senescence; D002648:Child; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D015473:Leukemia, Promyelocytic, Acute / Q000175:diagnosis / Q000378:metabolism; D008856:Microscopy, Fluorescence / Q000379:methods*; D008875:Middle Aged; D012516:Osteosarcoma / Q000175:diagnosis / Q000378:metabolism; D012509:Sarcoma / Q000235:genetics / Q000378:metabolism*; D019098:Telomerase / Q000378:metabolism; D016615:Telomere / Q000648:ultrastructure*; D013964:Thyroid Neoplasms / Q000378:metabolism; D013997:Time Factors
D019098:Telomerase