Dipeptidyl peptidase-4 is associated with myogenesis in patients with adolescent idiopathic scoliosis possibly via mediation of insulin sensitivity.

BACKGROUND: Abnormal metabolic features have been previously described in adolescent idiopathic scoliosis (AIS) patients. As an important regulator involved in energy metabolism, DPP-4 activity was reported to be remarkably decreased in osteoblasts of AIS patients. To date, there was still a lack of knowledge concerning the role of DPP-4 in the myogenesis of AIS. METHODS: Circulation DPP-4 level was assessed in the serum of 80 AIS girls and 50 healthy controls by ELISA. Myoblasts were purified from muscle specimens of AIS patients and LDH controls, and then treated with metabolic effectors including glucose and insulin. CCK-8 assay was used to assess the cell viability and myotube fusion index was calculated to evaluate myogenesis ability. Gene expressions of downstream signals of DPP-4 were evaluated by RT-qPCR and Western blot respectively. RESULTS: AIS girls had remarkably down-expressed DPP-4 in both serum level (0.76 fold) and tissue (0.68 fold) level. Treatment with metabolic effectors led to significantly increased DPP-4 expression in the control cells, while there was no increase of DPP-4 in AIS cells. CCK-8 assay showed that the proliferation rate of control cells was significantly increased after being treated. Remarkably higher fusion index was also observed in the treated control cells. By contrast, the fusion index and cell proliferation rate were comparable between the treated and the untreated AIS cells. CONCLUSIONS: Our study suggested a potential role of DPP-4 in abnormal metabolic condition of AIS patients. Compared with control cells, AIS myoblasts presented obviously impaired sensitivity to the treatment of glucose and insulin. Aberrant DPP-4 expression could lead to impaired insulin sensitivity in myoblasts and further influence the cell viability during myogenesis. The molecular mechanism connecting DPP-4 and insulin-related signaling in AIS is worthy of further investigation.

Investigating Role of IRX Family in Development of Female Adolescent Idiopathic Scoliosis: Which One Is Real Cause?

BACKGROUND: Previous studies showed that several variants located around the IRX family may have functional roles in the development of adolescent idiopathic scoliosis (AIS). However, there was lack of knowledge concerning the target gene of the region on 5p13.3 and the role of IRX genes in the etiology of AIS. This study aimed to validate the relationship between the IRX family and AIS in a large-scale general population and to further investigate the target gene of the region, which was associated with AIS. METHODS: SNP rs12517904 and rs117273909 were genotyped in 1323 patients and 1670 age-matched healthy controls. Paraspinal muscle was collected from 70 AIS patients and 20 congenital scoliosis patients. Student's t-test was used to compare the IRX1 expression between AIS patients and controls. The 1-way analysis of variance test was used to compare the expression of the IRX genes among different genotypes. RESULTS: For rs12517904, patients were found to have a significantly higher frequency of allele T than the controls (37.6% vs. 34.7%, P = 0.02). Allele T can significantly add to the risk of AIS with an odds ratio of 1.14. AIS patients were found to have significantly lower IRX1 expression than the controls. Patients with genotype TT were found to have significantly lower IRX1 expression than those with genotype GG. CONCLUSIONS: Our large-scale case control study validated that the IRX1 gene could be the disease-associated gene of AIS. The variant rs12517904 of the IRX1 gene is functionally associated with the development of AIS in the Chinese population. The role of IRX1 in the onset of AIS is worthy of further investigation.

Rare variant of HSPG2 is not involved in the development of adolescent idiopathic scoliosis: evidence from a large-scale replication study.

BACKGROUND: Rare variants of HSPG2 have recently been reported to function as a potential contributor to the susceptibility of adolescent idiopathic scoliosis (AIS) in the Caucasians. A replication study in the different population is warranted to validate the role of HSPG2 in AIS. The aim of this study was to determine the association between HSPG2 and AIS in the Chinese patients and to further investigate its influence on the phenotype of the patients. METHODS: SNVs p.Asn786Ser of HSPG2 was genotyped in 1752 patients and 1584 normal controls using multiple ligase detection reactions. The mRNA expression of HSPG2 in the paraspinal muscles was quantified for 90 patients and 26 controls. The The Student's t test was used to analyze the inter-group comparison of the HSPG2 expression. The relationship between the HSPG2 expression and the curve magnitude of the patients was analyzed by the Pearson correlation analysis. RESULTS: No case of mutation in the reported SNV p.Asn786Ser of HSPG2 was found in our cohort. The mRNA expression of HSPG2 in patients was comparable with that in the controls (0.0016 ± 0.0013 vs. 0.0019 ± 0.0012, p = 0.29). 42 patients with curve magnitude > 60 degrees were assigned to the severe curve group. The other 58 patients were assigned to the moderate curve group. These two groups were found to have comparable HSPG2 expression (0.0015 ± 0.0011 vs. 0.0017 ± 0.0014, p = 0.57). And there was no remarkable correlation between the expression level of HSPG2 and the curve severity (r = 0.131, p = 0.71). CONCLUSIONS: HSPG2 gene was not associated with the susceptibility or the phenotypes of AIS in the Chinese population. The whole HSPG2 gene can be sequenced in more AIS patients to identify potentially causative mutations.

MTHFR variant is associated with high-dose methotrexate-induced toxicity in the Chinese osteosarcoma patients.

BACKGROUND: The role of Methylene tetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms in the efficacy and toxicity of MTX-based therapy remains uncertain. Our purpose was to clarify whether these two polymorphisms are associated with the outcome of chemotherapy in a cohort of Chinese osteosarcoma (OS) patients treated by high-dose MTX. METHODS: 109 OS patients who had sequentially received high-dose MTX therapy were included in this study. Plasma MTX level was measured routinely at 0, 24, 48 and 72 h after the administration of MTX. Two variants of MTHFR were genotyped using TaqMan SNP Genotyping Assay, including rs1801133 (C667T) and rs1801131 (A1298C). The extent of toxicity induced by MTX, including hematological toxicity, hepatic toxicity, renal toxicity and mucositis, was scored from grade 1 to 4. Severe toxicity was defined as a grade score of ≥3. Patients were dichotomized as follows: grade <3 or ≥3 for toxicity, and ≤0.2 µmol/L or >0.2 µmol/L for plasma MTX level at 72 h. The frequencies of genotypes and allele were compared between the dichotomized groups with the Chi-square test. RESULTS: 24.8% (27/109) of the patients were found to have significantly high plasma MTX level at the 72 h. Patients with high MTX level at 72 h were found to have significantly higher frequency of genotype TT of rs1801133 (p = 0.002). As for rs1801131, no significant association was found with plasma MTX level. Patients with severe hepatic toxicity or mucositis were found to have remarkably higher incidence of genotype TT of rs1801133 than those with mild toxicity (33.3% vs. 14.8%, p = 0.04 for hepatic toxicity; 34.8% vs. 19.8%, p = 0.05 for mucositis). CONCLUSIONS: Variant rs1801133 was confirmed to have remarkable influence on the MTX-induced toxicity. We recommend identification of the genotype of MTHFR variant prior to the application of high-dose MTX to OS patients, which could be an important predictor to screen severe toxicities and thus improve treatment outcomes.

Grayscale Inversion View Can Improve the Reliability for Measuring Proximal Junctional Kyphosis in Adolescent Idiopathic Scoliosis.

BACKGROUND: Proximal junctional kyphosis (PJK) is a common phenomenon after long segmental fusion surgery of adolescent idiopathic scoliosis. However, the inability to reliably identify vertebral endplates on lateral upright radiographs has made an accurate measurement of proximal junctional angle (PJA) technically impossible in many patients. The aim of this study was to determine whether a grayscale inversion view is more reliable to measure PJA and to assess PJK accurately. METHODS: A total of 162 patients with adolescent idiopathic scoliosis who underwent posterior spinal fusion surgeries were included in this study. PJA was measured on preoperative lateral standing films using 3 methods (upper-instrumented vertebrae [UIV] + 1, UIV + 2, and UIV to T2) on both standard view and grayscale inversion view. Two physicians independently measured the PJA twice at a 1-month interval. Intra- and interobserver reliabilities were compared between the 2 radiographic views. Forty patients with preoperative magnetic resonance imaging (MRI) scans were randomly selected. PJA was measured for these patients on both views of lateral standing films and MRI images. The correlation coefficients between PJA obtained on MRI and PJA obtained on radiographs with different views were calculated respectively. RESULTS: The intraclass correlation coefficients were greater in a grayscale inversion view than in a standard view in all 3 methods for both observers, and the intraclass correlation coefficients of interobserver reliabilities also were greater in a grayscale inversion view. The correlation coefficient between PJA obtained on grayscale inversion view and preoperative MRI was greater in all methods compared with standard view. CONCLUSIONS: Grayscale inversion view can be a more reliable tool for the evaluation of PJK as compared with the conventional measurement. We recommend the application of a grayscale inversion view to measure PJA and assess PJK in clinical practice, particularly for patients instrumented to the upper thoracic spine.

A promoter variant of lncRNA GAS5 is functionally associated with the development of osteosarcoma.

BACKGROUND: Previous studies showed that genetic variant rs145204276 in the promoter region of GAS5 was associated with the development of human cancer including colorectal cancer and hepatocellular cancer. This study aimed to investigate the role of rs145204276 in the development of osteosarcoma (OS). METHODS: 132 OS patients and 1270 healthy controls were recruited for the genotyping analysis of rs145204276. Promoter methylation level of GAS5 was determined for all patients. The tumor tissues and the adjacent normal tissue were collected from 42 patients during surgery and the relative expression of GAS5 was then quantified by Real-time PCR. The Chi-square test was used to determine the difference of genotype and allele frequency between the patients and the controls. The gene expression and the percentage of methylation alleles were compared among different genotypes of rs145204276 with One-way ANOVA test. RESULTS: Compared with the controls, patients were found to have significantly lower rate of genotype del/del (7.6% vs. 8.7%, p = 0.024). The frequency of allele del was significantly lower in the patients than in the controls (23.5% vs. 30.1%, p = 0.021). Compared with than patients with genotype ins/ins, those with genotype del/del had remarkably higher expression of GAS5 (0.0033 ±â€¯0.0019 vs. 0.0018 ±â€¯0.0006, p < 0.001). Patients with genotype del/del were found to have obviously hypermethylation at the 7th CpG site as compared with those with genotype ins/ins (38.7% ±â€¯21.1% vs. 20.5% ±â€¯8.2%, p < 0.001). CONCLUSIONS: The genetic variant rs145204276 is functionally associated with the susceptibility of OS, which can function as a protective factor in the incidence of OS possibly through the regulation of GAS5.