title: Low expression of PHLPP1 in sacral chordoma and its association with poor prognosis.
abstract: Sacral chordoma is a rare spine tumor with a high recurrence rate even after optimal therapy. Previous studies have demonstrated that the PI3K/AKT pathway plays a pivotal role in chordoma, and high expression of pAKT is associated with poor prognosis. Recently, PHLPP was recognized to be a tumor suppressor that targets AKT. We analyzed the expression of PHLPP1 and AKT2 in 37 chordoma samples and 11 fetal nucleus pulposus samples by immunohistochemical staining. Of the chordoma cases, 40.5% (15/37) showed strong cytoplasmic staining (score ≥3) for PHLPP1, which was significantly lower than the 90.9% (10/11) of fetal nucleus pulposus samples (P = 0.004). Conversely, strong immunohistochemical staining for AKT2 was observed in 75.7% (28/37) of chordoma samples, which was significantly higher than 36.4% (4/11) of fetal nucleus pulposus (P = 0.021). Kaplan-Meier survival curves and log-rank test showed that patients with high expression of PHLPP1 experienced longer progression free survival time than those with low PHLPP1 expression (P = 0.011). Further multivariate Cox regression analysis indicated that PHLPP1 expression level and surgical approaches were independent risk factors for chordoma recurrence (P = 0.023 and P = 0.022). However, PHLPP1 expression was not statistically related to patients' total survival time. Conclusively, our results suggest that PHLPP1 plays a crucial role in sacral chordoma, and may be a promising biomarker for prognosis. Meanwhile, manipulation of PHLPP1 expression is also a potential therapeutic approach for the treatment of sacral chordoma.
authors.affiliation: Department of Orthopedics, The First Affiliated Hospital of Soochow University Suzhou, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Orthopedics, The First Affiliated Hospital of Soochow University Suzhou, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Department of Orthopedics, The First Affiliated Hospital of Soochow University Suzhou, China.
authors.forename: Guizhong
authors.initials: G
authors.lastname: Wu
authors.affiliation: Department of Orthopedics, The First Affiliated Hospital of Soochow University Suzhou, China.
authors.forename: Dawei
authors.initials: D
authors.lastname: Song
authors.affiliation: Department of Orthopedics, The First Affiliated Hospital of Soochow University Suzhou, China.
authors.forename: Kangwu
authors.initials: K
authors.lastname: Chen
authors.affiliation: Department of Orthopedics, The First Affiliated Hospital of Soochow University Suzhou, China.
authors.forename: Huilin
authors.initials: H
authors.lastname: Yang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis*; D002817:Chordoma / Q000401:mortality / Q000473:pathology*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000032:analysis / Q000096:biosynthesis*; D010749:Phosphoprotein Phosphatases / Q000032:analysis / Q000096:biosynthesis*; D016133:Polymerase Chain Reaction; D011379:Prognosis; D016016:Proportional Hazards Models; D012447:Sacrum / Q000473:pathology; D013125:Spinal Neoplasms / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; D009687:Nuclear Proteins; C400601:PHLPP1 protein, human; D010749:Phosphoprotein Phosphatases
keywords: AKT2; PHLPP1; Sacral chordoma; tumor suppressor
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