SPSB1-mediated inhibition of TGF-β receptor-II impairs myogenesis in inflammation

Mutant RAS-driven Secretome Causes Skeletal Muscle Defects in Breast Cancer

Cancer-induced skeletal muscle defects differ in severity between individuals with the same cancer type. Cancer subtype-specific genomic aberrations are suggested to mediate these differences, but experimental validation studies are very limited. We utilized three different breast cancer patient-derived xenograft (PDX) models to correlate cancer subtype with skeletal muscle defects. PDXs were derived from brain metastasis of triple-negative breast cancer (TNBC), estrogen receptor-positive/progesterone receptor-positive (ER+/PR+) primary breast cancer from a BRCA2-mutation carrier, and pleural effusion from an ER+/PR- breast cancer. While impaired skeletal muscle function as measured through rotarod performance and reduced levels of circulating and/or skeletal muscle miR-486 were common across all three PDXs, only TNBC-derived PDX activated phospho-p38 in skeletal muscle. To further extend these results, we generated transformed variants of human primary breast epithelial cells from healthy donors using HRASG12V or PIK3CAH1047R mutant oncogenes. Mutations in RAS oncogene or its modulators are found in approximately 37% of metastatic breast cancers, which is often associated with skeletal muscle defects. Although cells transformed with both oncogenes generated adenocarcinomas in NSG mice, only HRASG12V-derived tumors caused skeletal muscle defects affecting rotarod performance, skeletal muscle contraction force, and miR-486, Pax7, pAKT, and p53 levels in skeletal muscle. Circulating levels of the chemokine CXCL1 were elevated only in animals with tumors containing HRASG12V mutation. Because RAS pathway aberrations are found in 19% of cancers, evaluating skeletal muscle defects in the context of genomic aberrations in cancers, particularly RAS pathway mutations, may accelerate development of therapeutic modalities to overcome cancer-induced systemic effects.

SIGNIFICANCE

Mutant RAS- and PIK3CA-driven breast cancers distinctly affect the function of skeletal muscle. Therefore, research and therapeutic targeting of cancer-induced systemic effects need to take aberrant cancer genome into consideration.

Complex interplay of oral health, muscle and bone metabolism, and frailty in older individuals

OBJECTIVES

To investigate molecular and clinical background of associations among oral health, muscle and bone metabolism, and frailty incidence in patients with fall and fracture history.

MATERIALS AND METHODS

In total, 88 elderly participants (mean age 71.9 ± 5.8 years) with the distal radius fractures were included. Participants were divided into three groups based on an Oral Health Assessment Tool score. Fried criteria and Mini-nutritional assessments were adopted to diagnose frailty and malnutrition, respectively. Blood samples were collected and analyzed for serum levels of bone turnover markers, proteins, insulin-like growth factor-1, 25-hydroxyvitamin D, and inflammatory cytokines. The mRNA levels of markers of inflammation, muscle synthesis and wasting, and muscle homeostasis regulator in the pronator quadratus muscle were analyzed.

RESULTS

Patients with deteriorated oral health demonstrated a higher prevalence of frailty and malnutrition. Significantly lower serum levels of total protein and higher concentrations of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were detected in patients with poor oral health. Significant interaction effects between oral health and frailty level in gait speed, serum TNF-α, IL-1β, and total protein levels were exhibited. Significantly different mRNA expression levels in the pronator quadratus muscle of TNF-α, IL-1β, NF kB, MYOG, and FOXO1 following the oral health were detected.

CONCLUSION

This study highlights relationship between oral health, nutritional uptake, systemic inflammation, and their combined impact on muscle and bone metabolism, ultimately affecting frailty development in the aging populations.

CLINICAL RELEVANCE

A comprehensive understanding of mutual interactions among oral health, nutrition, and inflammation is essential for managing frailty.