Prognostic significance of p14ARF, p15INK4b, and p16INK4a inactivation in malignant peripheral nerve sheath tumors.
OBJECTIVE
p14(ARF), p15(INK4b), and p16(INK4a) are tumor suppressor genes that are located closely at 9p21 and are often coinactivated by genetic or epigenetic alterations. Malignant peripheral nerve sheath tumor (MPNST) is a rare sarcoma with poor prognosis. However, the prognostic implications of inactivation of p14(ARF), p15(INK4b), and p16(INK4a) in MPNSTs have not been adequately investigated. Here we carried out a genetic, epigenetic, and expression analysis of p14(ARF), p15(INK4b), and p16(INK4a), and clarified the prognostic significance of their inactivation in MPNSTs.


METHODS
p14(ARF), p15(INK4b), and p16(INK4a) protein expressions were assessed by immunohistochemistry in 129 formalin-fixed samples of MPNST including 85 primary tumors. Thirty-nine samples, for which frozen material was available, were also investigated by Western blotting and quantitative reverse transcription PCR (RT-PCR) to detect p14(ARF), p15(INK4b), and p16(INK4a) protein and mRNA expression, and by multiplex real-time PCR, PCR single strand conformation polymorphism and methylation-specific PCR to detect p14(ARF), p15(INK4b), and p16(INK4a) gene alterations.


RESULTS
Immunohistochemically decreased expressions of p14(ARF), p15(INK4b), and p16(INK4a) were observed in 48%, 54%, and 49% of primary MPNSTs, respectively, and were significantly correlated with their concordant mRNA levels. As for gene alterations, homozygous deletion of CDKN2A was detected in one third of the cases. Inactivation of p14(ARF) and p16(INK4a) was associated with poor prognosis by both univariate and multivariate analyses. Furthermore, cases with inactivation of all p14(ARF), p15(INK4b), and p16(INK4a) genes showed the worst prognosis in a combined prognostic assessment.


CONCLUSIONS
A comprehensive analysis of p14(ARF), p15(INK4b), and p16(INK4a) inactivation status provides useful prognostic information in MPNSTs.
Departments of Anatomic Pathology and Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka Sanno Hospital, Fukuoka, Japan.
Makoto
M
Endo
Chikashi
C
Kobayashi
Nokitaka
N
Setsu
Yusuke
Y
Takahashi
Kenichi
K
Kohashi
Hidetaka
H
Yamamoto
Sadafumi
S
Tamiya
Shuichi
S
Matsuda
Yukihide
Y
Iwamoto
Masazumi
M
Tsuneyoshi
Yoshinao
Y
Oda
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D050762:Cyclin-Dependent Kinase Inhibitor p15 / Q000235:genetics / Q000378:metabolism*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics / Q000378:metabolism*; D005260:Female; D019942:Genes, p16; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D018317:Nerve Sheath Neoplasms / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism*; D011379:Prognosis; D025803:Tumor Suppressor Protein p14ARF / Q000235:genetics / Q000378:metabolism*
C493966:CDKN2B protein, human; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16; D025803:Tumor Suppressor Protein p14ARF