Thermo-Chemical Resistance to Combination Therapy of Glioma Depends on Cellular Energy Level.

Thermal therapy has been widely used in clinical tumor treatment and more recently in combination with chemotherapy, where the key challenge is the treatment resistance. The mechanism at the cellular level underlying the resistance to thermo-chemical combination therapy remains elusive. In this study, we constructed 3D culture models for glioma cells (i.e., 3D glioma spheres) as the model system to recapitulate the native tumor microenvironment and systematically investigated the thermal response of 3D glioma spheres at different hyperthermic temperatures. We found that 3D glioma spheres show high viability under hyperthermia, especially under high hyperthermic temperatures (42 °C). Further study revealed that the main mechanism lies in the high energy level of cells in 3D glioma spheres under hyperthermia, which enables the cells to respond promptly to thermal stimulation and maintain cellular viability by upregulating the chaperon protein Hsp70 and the anti-apoptotic pathway AKT. Besides, we also demonstrated that 3D glioma spheres show strong drug resistance to the thermo-chemical combination therapy. This study provides a new perspective on understanding the thermal response of combination therapy for tumor treatment.

A positive mechanobiological feedback loop controls bistable switching of cardiac fibroblast phenotype.

Cardiac fibrosis is associated with activation of cardiac fibroblasts (CFs), a pathological, phenotypic transition that is widely believed to be irreversible in the late stages of disease development. Sensing of a stiffened mechanical environment through regulation of integrin-based adhesion plaques and activation of the Piezo1 mechanosensitive ion channel is known to factor into this transition. Here, using integrated in vitro and in silico models, we discovered a mutually reinforcing, mechanical positive feedback loop between integrin ß1 and Piezo1 activation that forms a bistable switch. The bistable switch is initiated by perturbations in matrix elastic modulus that amplify to trigger downstream signaling involving Ca2+ and YAP that, recursively, leads fibroblasts to further stiffen their environment. By simultaneously interfering with the newly identified mechanical positive feedback loop and modulating matrix elastic modulus, we reversed markers of phenotypical transition of CF, suggesting new therapeutic targets for fibrotic disease.

Evaluation of Growth Hormone Therapy in Seven Chinese Children With Familial Short Stature Caused by Novel ACAN Variants.

Objective: ACAN gene variants are an important cause of familial short stature (FSS). Appropriate growth-promoting therapies effectively improve the patient height. Here, we report a therapeutic assessment of cases of seven families of FSS patients with heterozygous ACAN variants. Our findings provide a valuable theoretical basis for the clinical diagnosis and treatment of this disease. Methods: From December 2020 to June 2021, 32 FSS patients were examined in Tianjin Medical University General Hospital (Tianjin, China) by whole-exome sequencing to determine whether ACAN variants were present. Their clinical data were summarized and scrupulously analyzed. Results: We found seven novel heterozygous ACAN variants: c.1051 + 2T > A, c.313T > C (p.S105P), c.2660C > G (p.S887X), c.2153C > A (p. T718K), c.7243delG (p.D2415Tfs*4), c.2911G > T (p.G971X), c.758-7T > C. All seven patients had proportionate short stature and mild skeletal dysplasia. Endocrine examination results were normal. Only one of the patients had an advanced bone age (1.1 years older than chronological age), whereas the other patients had normal bone ages. All of them had a family history of short stature, with or without osteoarthritis or intervertebral disc disease. All seven patients accepted treatment with recombinant human growth hormone (rhGH) and were regularly followed up. One patient did not come at the follow-up visit. The height of the remaining six patients before and after the treatment was -2.89 ± 0.68 SDS, -1.91 ± 0.93 SDS, respectively, with a treatment course of 1.85 ± 1.91 years. A good therapeutic response was observed in all of them. Conclusions: In this study, seven novel heterozygous variants in ACAN were discovered, which expanded the spectrum of the already established ACAN pathogenic variants. In FSS cohort, the proportion of ACAN variants accounted was large. The treatment with rhGH effectively increased the patient height, but further studies with longer follow-up periods and more extensive observations are required to elucidate the long-term effect.

The Plasticity of Nanofibrous Matrix Regulates Fibroblast Activation in Fibrosis.

Natural extracellular matrix (ECM) mostly has a fibrous structure that supports and mechanically interacts with local residing cells to guide their behaviors. The effect of ECM elasticity on cell behaviors has been extensively investigated, while less attention has been paid to the effect of matrix fiber-network plasticity at microscale, although plastic remodeling of fibrous matrix is a common phenomenon in fibrosis. Here, a significant decrease is found in plasticity of native fibrotic tissues, which is associated with an increase in matrix crosslinking. To explore the role of plasticity in fibrosis development, a set of 3D collagen nanofibrous matrix with constant modulus but tunable plasticity is constructed by adjusting the crosslinking degree. Using plasticity-controlled 3D culture models, it is demonstrated that the decrease of matrix plasticity promotes fibroblast activation and spreading. Further, a coarse-grained molecular dynamic model is developed to simulate the cell-matrix interaction at microscale. Combining with molecular experiments, it is revealed that the enhanced fibroblast activation is mediated through cytoskeletal tension and nuclear translocation of Yes-associated protein. Taken together, the results clarify the effects of crosslinking-induced plasticity changes of nanofibrous matrix on the development of fibrotic diseases and highlight plasticity as an important mechanical cue in understanding cell-matrix interactions.

Matrix stiffness controls cardiac fibroblast activation through regulating YAP via AT1 R.

Cardiac fibrosis is a common pathway leading to heart failure and involves continued activation of cardiac fibroblasts (CFs) into myofibroblasts during myocardium damage, causing excessive deposition of the extracellular matrix (ECM) and thus increases matrix stiffness. Increasing evidence has shown that stiffened matrix plays an important role in promoting CF activation and cardiac fibrosis, and several signaling factors mediating CF mechanotransduction have been identified. However, the key molecules that perceive matrix stiffness to regulate CF activation remain to be further explored. Here, we detected significantly increased expression and nuclear localization of Yes-associated protein (YAP) in native fibrotic cardiac tissues. By using mechanically regulated in vitro cell culture models, we found that a stiff matrix-induced high expression and nuclear localization of YAP in CFs, accompanied by enhanced cell activation. We also demonstrated that YAP knockdown decreased fibrogenic response of CFs and that YAP overexpression promoted CF activation, indicating that YAP plays an important role in mediating matrix stiffness-induced CF activation. Further mechanistic studies revealed that the YAP pathway is an important signaling branch downstream of angiotensin II type 1 receptor in CF mechanotransduction. The findings help elucidate the mechanism of fibrotic mechanotransduction and may contribute to the development of new approaches for treating fibrotic diseases.