Cardiovascular Consequences of Skeletal Muscle Impairments in Breast Cancer

Research Quality and Impact of Cardiac Rehabilitation in Cancer Survivors

Background

Cardiac rehabilitation (CR) is endorsed to improve cardiovascular outcomes in cancer survivors. The quality of CR-based research in oncology has not been assessed.

Objectives

The aim of this study was to evaluate the quality of reporting and evidence from CR-based intervention studies in oncology and to explore associations between intervention participation and outcomes.

Methods

Systematic searches of 5 databases were conducted (January 2020) and updated (September 2021). Randomized and nonrandomized studies evaluating CR-based interventions in adult cancer survivors during and after treatment were eligible. Independent reviewers extracted data using 2 reporting guidelines (Template for Intervention Description and Replication and Consolidated Standards for Reporting Trials Harms extension), risk of bias (ROB) assessment tools (Cochrane ROB 2.0 and Cochrane Risk of Bias in Non-Randomized Studies of Interventions), and a combined inventory (Tool for the Assessment of Study Quality and reporting in Exercise). A meta-analysis was used to explore pre-intervention/post-intervention differences for commonly assessed outcomes.

Results

Ten studies involving data from 685 survivors were included. The mean quality scores for intervention reporting (Template for Intervention Description and Replication) and harms (Consolidated Standards for Reporting Trials Harms extension) were 62% and 17%, respectively. There was moderate-to-high ROB across nonrandomized (Cochrane Risk of Bias in Non-Randomized Studies of Interventions score: 25%) and randomized (ROB 2.0 score: 50%) studies. The mean standardized cardiorespiratory fitness was higher (0.42; 95% CI: 0.27-0.57), fatigue was lower (−0.45; 95% CI: −0.55 to −0.34), and percent body fat (0.07; 95% CI: −0.23 to 0.38) was not different in survivors completing CR compared with those not completing CR.

Conclusions

CR-based studies in oncology have low-to-moderate reporting quality and moderate-to-high ROB limiting interpretation, reproducibility, and translation of this evidence into practice.

A novel function of CREG in metabolic disorders

Metabolic disorders are public health problems that require prevention and new efficient drugs for treatment. Cellular repressor of E1A-stimulated genes (CREG) is ubiquitously expressed in mature tissues and cells in mammals and plays a critical role in keeping cells or tissues in a mature, homeostatic state. Recently, CREG turns to be an important mediator in the development of metabolic disorders. Here in this review, we briefly discuss the structure and molecular regulation of CREG along with the therapeutic strategy to combat the metabolic disorders.

CREG1 improves the capacity of the skeletal muscle response to exercise endurance via modulation of mitophagy

CREG1 (cellular repressor of E1A-stimulated genes 1) is involved in tissue homeostasis and influences macroautophagy/autophagy to protect cardiovascular function. However, the physiological and pathological role of CREG1 in the skeletal muscle is not clear. Here, we established a skeletal muscle-specific creg1 knockout mouse model (creg1;Ckm-Cre) by crossing the Creg1-floxed mice (Creg1^fl/fl) with a transgenic line expressing Cre recombinase under the muscle-specific Ckm (creatine kinase, muscle) promoter. In creg1;Ckm-Cre mice, the exercise time to exhaustion and running distance were significantly reduced compared to Creg1^fl/fl mice at the age of 9 months. In addition, the administration of recombinant (re)CREG1 protein improved the motor function of 9-month-old creg1;Ckm-Cre mice. Moreover, electron microscopy images of 9-month-old creg1;Ckm-Cre mice showed that the mitochondrial quality and quantity were abnormal and associated with increased levels of PINK1 (PTEN induced putative kinase 1) and PRKN/PARKIN (parkin RBR E3 ubiquitin protein ligase) but reduced levels of the mitochondrial proteins PTGS2/COX2, COX4I1/COX4, and TOMM20. These results suggested that CREG1 deficiency accelerated the induction of mitophagy in the skeletal muscle. Mechanistically, gain-and loss-of-function mutations of Creg1 altered mitochondrial morphology and function, impairing mitophagy in C2C12 cells. Furthermore, HSPD1/HSP60 (heat shock protein 1) (401-573 aa) interacted with CREG1 (130-220 aa) to antagonize the degradation of CREG1 and was involved in the regulation of mitophagy. This was the first time to demonstrate that CREG1 localized to the mitochondria and played an important role in mitophagy modulation that determined skeletal muscle wasting during the growth process or disease conditions.Abbreviations: CCCP: carbonyl cyanide m-chlorophenylhydrazone; CKM: creatine kinase, muscle; COX4I1/COX4: cytochrome c oxidase subunit 4I1; CREG1: cellular repressor of E1A-stimulated genes 1; DMEM: dulbecco's modified eagle medium; DNM1L/DRP1: dynamin 1-like; FCCP: carbonyl cyanide p-trifluoro-methoxy phenyl-hydrazone; HSPD1/HSP60: heat shock protein 1 (chaperonin); IP: immunoprecipitation; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MFF: mitochondrial fission factor; MFN2: mitofusin 2; MYH1/MHC-I: myosin, heavy polypeptide 1, skeletal muscle, adult; OCR: oxygen consumption rate; OPA1: OPA1, mitochondrial dynamin like GTPase; PINK1: PTEN induced putative kinase 1; PPARGC1A/PGC-1α: peroxisome proliferative activated receptor, gamma, coactivator 1 alpha; PRKN/PARKIN: parkin RBR E3 ubiquitin protein ligase; PTGS2/COX2: prostaglandin-endoperoxide synthase 2; RFP: red fluorescent protein; RT-qPCR: real-time quantitative PCR; SQSTM1/p62: sequestosome 1; TFAM: transcription factor A, mitochondrial; TOMM20: translocase of outer mitochondrial membrane 20; VDAC: voltage-dependent anion channel.