A transforming growth factor-beta receptor-interacting protein frequently mutated in human ovarian cancer.
Ovarian carcinomas, particularly recurrent forms, are frequently resistant to transforming growth factor-beta (TGF-beta)-mediated growth inhibition. However, mutations in the TGF-beta receptor I and receptor II (TbetaR-I and TbetaR-II) genes have only been reported in a minority of ovarian carcinomas, suggesting that alterations in TGF-beta-signaling components may play an important role in the loss of TGF-beta responsiveness. Using laser-capture microdissection and nested reverse-transcription-PCR, we found that km23, which interacts with the TGF-beta receptor complex, is altered at a high frequency in human ovarian cancer patients. A novel form of km23, missing exon 3 (Deltaexon3-km23), was found in 2 of 19 tumor tissues from patients with ovarian cancer. In addition to this alteration, a stop codon mutation (TAA --> CAC) was detected in two patients. This alteration results in an elongated protein, encoding 107-amino-acid residues (Delta107km23), instead of the wild-type 96-amino-acid form of km23. Furthermore, five missense mutations (T38I, S55G, T56S, I89V, and V90A) were detected in four patients, providing a total alteration rate of 42.1% (8 of 19 cases) in ovarian cancer. No km23 alterations were detected in 15 normal tissues. Such a high alteration rate in ovarian cancer suggests that km23 may play an important role in either TGF-beta resistance or tumor progression in this disease. In keeping with these findings, the functional studies described herein indicate that both the Deltaexon3-km23 and S55G/I89V-km23 mutants displayed a disruption in binding to the dynein intermediate chain in vivo, suggesting a defect in cargo recruitment to the dynein motor complex. In addition, the Deltaexon3-km23 resulted in an inhibition of TGF-beta-dependent transcriptional activation of both the p3TP-lux and activin responsive element reporters. Collectively, our results suggest that km23 alterations found in ovarian cancer patients result in altered dynein motor complex formation and/or aberrant transcriptional regulation by TGF-beta.
Ding
Wei
W
Department of Pharmacology and Health Evaluation Sciences, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA.
Tang
Qian
Q
Espina
Virginia
V
Liotta
Lance A
LA
Mauger
David T
DT
Mulder
Kathleen M
KM
D000368:Aged; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics*; D004398:Dyneins; D005091:Exons / Q000235:genetics; D005260:Female; D006801:Humans; D008875:Middle Aged; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000378:metabolism; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction
D002352:Carrier Proteins; D029721:Drosophila Proteins; D018125:Receptors, Transforming Growth Factor beta; D004398:Dyneins