Pseudotear Sign of the Anterior Horn of the Meniscus.

PURPOSE: To observe the morphology of the transverse geniculate ligament of the knee (TGL) by magnetic resonance imaging (MRI) and to analyze the cause of the pseudotear sign of the anterior horn of the meniscus caused by the TGL. METHODS: Patients who underwent MRI examination of the knee joint in the orthopaedics department of our hospital from July 2016 to August 2019 were identified. The occurrence rate, length, width, thickness, cross-sectional shape, pattern, appearance, and position relative to the anterior horn of the lateral and medial meniscus and anatomical variations were observed by multiplane and multisequence MRI. The frequency and cause of the pseudotear sign also were observed. RESULTS: The data of 101 patients were analyzed. Among them, 60 were male, and 41 were female. The average age was 42.01 (18-75) years. The occurrence rate of the TGL was 67.3% (68/101), the average length was 38.75 ± 3.56 mm, the median coronal diameter was 1.79 ± 0.60 mm, the median sagittal diameter was 1.88 ± 0.35 mm, and the cross-sectional morphology was mostly oval and round. There were 5 types of TGL connection to the anterior horn of the medial meniscus: type 1, located at the front edge; type 2, located at the upper front edge; type 3, located at the upper edge; type 4, located at the back upper edge; and type 5, was located at the back edge of the anterior horn of the medial meniscus. There was only one type of TGL insertion into the anterior horn of the lateral meniscus, located at the anterior superior edge of the anterior horn of the lateral meniscus. There were 4 cases of the pseudotear sign in the anterior horn of the meniscus, 3 in the lateral meniscus and 1 in the medial meniscus. The pseudotear sign of the anterior horn of the meniscus caused by the TGL was observed at a rate of 5.88% (4/68). CONCLUSIONS: In MRI examination of the knee, the anterior horn of the meniscus sometimes shows a pseudotear sign. According to the shape and route of the TGL on MRI and the direction and position of the pseudotear sign of the anterior horn of the meniscus, true and false tears of the anterior horn of the meniscus can be identified. LEVEL OF EVIDENCE: Level III, diagnostic study (retrospective, noncomparative, observational case series without a consistently applied reference "gold" standard).

PLA2G10 facilitates the cell-cycle progression of soft tissue leiomyosarcoma cells at least by elevating cyclin E1/CDK2 expression.

Soft tissue leiomyosarcoma (STLMS) is a major histological subtype of adult sarcoma. Although the molecular mechanisms ofLMS have been gradually revealed, no valid therapeutic targets have been identified. In this study, we performed a systematic screening to explore relapse-associated genes in STLMS, using data from The Cancer Genome Atlas-Sarcoma (TCGA-SARC). Then, we investigated the functional role of the gene with the best relapse-prediction value in STLMS by both in-vitro and in-vivo studies. Results showed that AMH and PLA2G10 were two genes with area under curve (AUC) values higher than 0.80 in ROC analysis when detecting relapse. Patients in the high AMH or PLA2G10 expression group had significantly worse relapse-free survival (RFS) compared to the respective low expression group. PLA2G10 was highly expressed in STLMS, but not in other sarcoma subtypes. PLA2G10 overexpression promoted SK-LMS-1 cell growth and G1/S transition, while PLA2G10 knockdown slowed the growth and resulted in G1 phase arrest. PLA2G10 overexpression markedly increased the expression of CDK2 and cyclin E1, but did not influence CDK4, CDK6, cyclin D1, CDK1 or cyclin A expression. PLA2G10 overexpression enhanced SK-LMS-1 cell-derived xenograft tumor growth in nude mice, while PLA2G10 inhibition slowed the growth. Mutation of two critical catalyzing amino acid residues (p.H88A and p.D89A) abrogated the capability of PLA2G10 to catalyze the production of arachidonic acid (AA), and also canceled the regulatory effects on cyclin E1 and CDK2 expression, as well as G1/S transition. In conclusion, PLA2G10 was a specific relapse-associated gene in STLMS. It facilitated the cell-cycle progression of STLMS cells at least by elevating the expression of cyclin E1 and CDK2. The hydrolytic activity was crucial for its oncogenic properties.