Lactate increases myotube diameter via activation of MEK/ERK pathway in C2C12 cells

AIM

Lactate is produced in and released from skeletal muscle cells. Lactate receptor, G-protein-coupled receptor 81 (GPR81), is expressed in skeletal muscle cells. However, a physiological role of extracellular lactate on skeletal muscle is not fully clarified. The purpose of this study was to investigate extracellular lactate-associated morphological changes and intracellular signals in C2C12 skeletal muscle cells.

METHODS

Mouse myoblast C2C12 cells were differentiated for 5 days to form myotubes. Sodium lactate (lactate) or GPR81 agonist, 3,5-dihydroxybenzoic acid (3,5-DHBA), was administered to the differentiation medium.

RESULTS

Lactate administration increased the diameter of C2C12 myotubes in a dose-dependent manner. Administration of 3,5-DHBA also increased myotube diameter. Not only lactate but also 3,5-DHBA upregulated the phosphorylation level of mitogen-activated protein kinase kinase 1/2 (MEK1/2), p42/44 extracellular signal-regulated kinase-1/2 (ERK1/2) and p90 ribosomal S6 kinase (p90RSK). MEK inhibitor U0126 depressed the phosphorylation of ERK-p90RSK and increase in myotube diameter induced by lactate. On the other hand, both lactate and 3,5-DHBA failed to induce significant responses in the phosphorylation level of Akt, mammalian target of rapamycin, p70 S6 kinase and protein degradation-related signals.

CONCLUSION

These observations suggest that lactate-associated increase in the diameter of C2C12 myotubes is induced via activation of GRP81-mediated MEK/ERK pathway. Extracellular lactate might have a positive effect on skeletal muscle size.

Sagittal alignment and mobility of the thoracolumbar spine are associated with radiographic progression of secondary hip osteoarthritis

OBJECTIVE

To identify predictors of radiographic progression of hip osteoarthritis (OA) over 12 months among functional hip impairments and spinal alignment and mobility.

DESIGN

Fifty female patients with secondary hip OA, excluding those with end-stage hip OA, participated in this prospective cohort study. Joint space width (JSW) of the hip was measured at baseline and 12 months later. With radiographic progression of hip OA over 12 months (>0.5 mm in JSW) as dependent variable, logistic regression analyses were performed to identify predictors for hip OA progression among functional impairments of the hip and spine with and without adjustment for age, body mass index (BMI), and minimum JSW at baseline. The independent variables were hip pain, Harris hip score (HHS), hip morphological parameters, hip passive range of motion (ROM) and muscle strength, and alignment and mobility of the thoracolumbar spine at baseline.

RESULTS

Twenty-one (42.0%) patients demonstrated radiographic progression of hip OA. Multivariable logistic regression analysis showed that larger anterior inclination of the spine in standing position (adjusted OR [95% CI], 1.37 [1.04-1.80]; P = 0.028) and less thoracolumbar spine mobility (adjusted OR [95% CI], 0.96 [0.92-0.99]; P = 0.037) at baseline were statistically significantly associated with radiographic progression of hip OA, even after adjustment for age, BMI, and minimum JSW.

CONCLUSIONS

The findings suggest that spinal alignment and mobility should be considered when assessing risk and designing preventive intervention for radiographic progression of secondary hip OA.

Immunological classification of renal cell carcinoma patients based on phenotypic analysis of immune check-point molecules

OBJECTIVES

To clarify comprehensive immunological signature patterns of tumour tissue-infiltrating lymphocytes in patients with renal cell carcinoma and show its clinical significance.

MATERIALS AND METHODS

We investigated the surface marker expressions of tumour tissue-infiltrating lymphocytes quantitatively and classified them based on their functional populations. We extracted 109 sets of tumour tissue-infiltrating lymphocytes from 80 patients who underwent surgical resection of renal cell carcinoma, of which 44 tumour tissue-infiltrating lymphocytes were multiply extracted from 15 patients. Each tumour tissue-infiltrating lymphocyte was characterised on the basis of functional T-cell populations using ten surface marker expressions measured by flow cytometry.

RESULTS

All sets of the tumour tissue-infiltrating lymphocytes were classified into three groups, which correlated significantly with Fuhrman grade (OR 0.253, 95% CI 0.094-0.678, P = 0.006). Importantly, both overall metastasis-free survival (HR 0.449, 95% CI 0.243-0.832, P = 0.011) and recurrence-free survival (HR 0.475, 95% CI 0.238-0.948, P = 0.035) of the patients with the higher marker expressions were significantly inferior to those of the patients with the lower marker expressions by multivariate analysis. Six specific genes for this classification identified by microarray analysis verified our results using the TCGA KIRC data set. In addition, we discovered the presence of intra-tumoural diversity in the classification of 3 (20%) of the 15 patients.

CONCLUSIONS

This study showed that the presence of classable diversity in the immunological signature of tumour tissue-infiltrating lymphocytes correlated with prognosis and tumour aggressiveness that was observed even within individual tumours in some patients with renal cell carcinoma.

Randomized controlled trial of S-1 versus docetaxel in patients with non-small-cell lung cancer previously treated with platinum-based chemotherapy (East Asia S-1 Trial in Lung Cancer)

BACKGROUND

Chemotherapy remains a viable option for the management of advanced non-small-cell lung cancer (NSCLC) despite recent advances in molecular targeted therapy and immunotherapy. We evaluated the efficacy of oral 5-fluorouracil-based S-1 as second- or third-line therapy compared with standard docetaxel therapy in patients with advanced NSCLC.

PATIENTS AND METHODS

Patients with advanced NSCLC previously treated with ≥1 platinum-based therapy were randomized 1 : 1 to docetaxel (60 mg/m2 in Japan, 75 mg/m2 at all other study sites; day 1 in a 3-week cycle) or S-1 (80-120 mg/day, depending on body surface area; days 1-28 in a 6-week cycle). The primary endpoint was overall survival. The non-inferiority margin was a hazard ratio (HR) of 1.2.

RESULTS

A total of 1154 patients (577 in each arm) were enrolled, with balanced patient characteristics between the two arms. Median overall survival was 12.75 and 12.52 months in the S-1 and docetaxel arms, respectively [HR 0.945; 95% confidence interval (CI) 0.833-1.073; P = 0.3818]. The upper limit of 95% CI of HR fell below 1.2, confirming non-inferiority of S-1 to docetaxel. Difference in progression-free survival between treatments was not significant (HR 1.033; 95% CI 0.913-1.168; P = 0.6080). Response rate was 8.3% and 9.9% in the S-1 and docetaxel arms, respectively. Significant improvement was observed in the EORTC QLQ-C30 global health status over time points in the S-1 arm. The most common adverse drug reactions were decreased appetite (50.4%), nausea (36.4%), and diarrhea (35.9%) in the S-1 arm, and neutropenia (54.8%), leukocytopenia (43.9%), and alopecia (46.6%) in the docetaxel arm.

CONCLUSION

S-1 is equally as efficacious as docetaxel and offers a treatment option for patients with previously treated advanced NSCLC.

CLINICAL TRIAL NUMBER

Japan Pharmaceutical Information Center, JapicCTI-101155.

Correlation between the Expression of P-Glycoprotein and Multidrug-Resistant Phenotype in Transitional Cell Carcinoma of the Urinary Tract

The expression of a multidrug-resistant (MDR) gene product, P-glycoprotein, was examined immunohistochemically in 41 transitional cell carcinomas (TCCs) of the urinary tract. In 23 of these, chemosensitivity to adriamycin (ADM) and vinblastine (VBL) was also assessed by a microtiter succinate dehydrogenase inhibition test and the correlation between the expression of P-glycoprotein and MDR phenotype was investigated. P-glycoprotein was detected in 13 (72.2%) of the 18 untreated TCCs of the upper urinary tract (UUT), 6 (31.6%) of the 19 untreated TCCs of the bladder, and all of the 4 TCCs treated with M-VAC chemotherapy, respectively. Fourteen (87.5%) of the 16 TCCs with a positive expression of P-glycoprotein were resistant to ADM and VBL, whereas all of the 4 TCCs sensitive to both drugs were negative in the expression of P-glycoprotein. The succinate dehydrogenase activity of TCCs with a positive expression of P-glycoprotein was significantly higher than that of TCCs with a negative expression of P-glycoprotein (P < 0.05). Thus, there was a good correlation between the expression of P-glycoprotein and MDR phenotype in the chemosensitivity test. These results suggest that intrinsic MDR exists in some TCCs of the urinary tract, particularly UUT, and that the immunohistochemical investigation of P-glycoprotein may be useful for predicting the MDR phenotype in TCCs of the urinary tract.

Daily cumulative hip moment is associated with radiographic progression of secondary hip osteoarthritis

OBJECTIVE

To investigate whether higher daily cumulative hip moment at baseline is associated with subsequent radiographic progression of hip osteoarthritis (OA) over 12 months.

DESIGN

Fifty patients with secondary hip OA, excluding patients with end-stage hip OA, participated in this prospective cohort study. Joint space width (JSW) of the hip was measured at baseline and 12 months later. With radiographic progression of hip OA (>0.5 mm/year in JSW) as dependent variable (yes/no), univariable and multivariable logistic regression analyses were performed to assess the association between load-related parameters during gait (i.e., peak hip moment, hip moment impulse, and daily cumulative hip moment [product of hip moment impulse and mean steps/day]) and hip OA progression with and without adjustment for age, body weight, and minimum JSW.

RESULTS

Of the 50 patients (47.4 ± 10.7 years old), 21 (42.0%) were classified into the progression group. The higher daily cumulative hip moment in the frontal plane at baseline was statistically significantly associated with radiographic progression of hip OA (adjusted odds ratio (OR) [95% confidence interval (CI)], 1.34 [1.06-1.70]; P = 0.013). The higher daily cumulative hip moment in the sagittal plane was also approaching significance in its association with hip OA progression (adjusted OR, 1.80 [0.99-3.26]; P = 0.052).

CONCLUSIONS

In the female patients with secondary hip OA, higher daily cumulative hip moment, particularly in the frontal plane, was a predictor of radiographic progression of hip OA over 12 months. Reduction in daily cumulative hip moment by modification in gait and physical activity may potentially slow hip OA progression.