Augmented drug resistance of osteosarcoma cells within decalcified bone matrix scaffold: The role of glutamine metabolism.

Due to the lack of a precise in vitro model that can mimic the nature microenvironment in osteosarcoma, the understanding of its resistance to chemical drugs remains limited. Here, we report a novel three-dimensional model of osteosarcoma constructed by seeding tumor cells (MG-63 and MNNG/HOS Cl no. 5) within demineralized bone matrix scaffolds. Demineralized bone matrix scaffolds retain the original components of the natural bone matrix (hydroxyapatite and collagen type I), and possess good biocompatibility allowing osteosarcoma cells to proliferate and aggregate into clusters within the pores. Growing within the scaffold conferred elevated resistance to doxorubicin on MG-63 and MNNG/HOS Cl no. 5 cell lines as compared to two-dimensional cultures. Transcriptomic analysis showed an increased enrichment for drug resistance genes along with enhanced glutamine metabolism in osteosarcoma cells in demineralized bone matrix scaffolds. Inhibition of glutamine metabolism resulted in a decrease in drug resistance of osteosarcoma, which could be restored by α-ketoglutarate supplementation. Overall, our study suggests that microenvironmental cues in demineralized bone matrix scaffolds can enhance osteosarcoma drug responses and that targeting glutamine metabolism may be a strategy for treating osteosarcoma drug resistance.

Drug resistance mechanisms and progress in the treatment of EGFR-mutated lung adenocarcinoma.

According to global cancer data, lung cancer was the leading cause of cancer-related death in 2020. With the diversification of treatment strategies, the survival outcomes of patients with advanced lung cancer have improved significantly, but the 5-year overall survival rate remains <20%. Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are the preferred treatment for lung adenocarcinoma patients with EGFR-sensitive mutations; however, acquired drug resistance is inevitable. Osimertinib (a third-generation EGFR inhibitor) is the most commonly used drug for cancers with a secondary T790M mutation. Unfortunately, acquired drug resistance against third-generation drugs still emerges. The C797s mutation is the primary acquired resistance mechanism against Osimertinib. Research on fourth-generation EGFR-TKI drugs with a C797s mutation is currently at various experimental stages, and no drug has been approved for clinical use. In addition to the resistance mechanisms described above, HER2 amplification, MET amplification, PIK3A mutation, KRAS mutation, BRAF mutation, transformation to small cell lung cancer, transformation to lung squamous cell carcinoma, and EMT have been reported as mechanisms of acquired drug resistance to first-, second- and third-generation EGFR-TKIs. These mechanisms are noted in a relatively high proportion of tumors, but treatment options are limited. In recent years, immunotherapy has made progress in the treatment of several cancers, including advanced EGFR-mutated non-small cell lung cancer (NSCLC). Due to the relatively high frequency of EGFR mutation in patients with lung adenocarcinoma in China, an increased number of patients develop EGFR-TKI resistance, and subsequent treatment options are critical. This article reviews the mechanisms of drug resistance to different EGFR-TKIs and treatment progression, providing ideas for the follow-up treatment for EGFR-resistant patients.

Clinical Efficacy of Immune Checkpoint Inhibitors in Non-Small Cell Lung Cancer Patients with Liver Metastases: A Network Meta-Analysis of Nine Randomized Controlled Trials.

PURPOSE: This network meta-analysis (NMA) was conducted to compare the efficacy of immune checkpoint inhibitors in advanced non-small cell lung cancer (NSCLC) patients with liver metastases. MATERIALS AND METHODS: English literature was retrieved from the PubMed, American Society of Clinical Oncology, and European Society for Medical Oncology databases from January 2015 to January 2021. We pooled the overall survival (OS) and progression-free survival (PFS) hazard ratios (HRs) using an NMA and ranked treatments by the surface under the cumulative ranking curve. Publication bias was evaluated by Begg's and Egger's tests. STATA 15.0 was used for the sensitivity analysis, and the remaining statistical analyses were performed using R 4.0.2. RESULTS: Nine eligible phase III randomized controlled trials were included, including 1,141 patients with liver metastases. Pembrolizumab+chemotherapy ranked highest, followed by atezolizumab+bevacizumab+chemotherapy and nivolumab. However, no significant difference in OS rates was observed across these three treatments (HR, 0.98; 95% confidence interval [CI], 0.43 to 2.22 for pembrolizumab+chemotherapy vs. atezolizumab+bevacizumab+chemotherapy; HR, 0.91; 95% CI, 0.52 to 1.57 for pembrolizumab+chemotherapy vs. nivolumab). Regarding the PFS rate, atezolizumab+bevacizumab+chemotherapy and pembro-lizumab+chemotherapy ranked highest and no significant difference was observed between them (HR, 0.79; 95% CI, 0.36 to 1.70 for atezolizumab+bevacizumab+chemotherapy vs. pembrolizumab+chemotherapy). CONCLUSION: Pembrolizumab+chemotherapy, atezolizumab+bevacizumab+chemotherapy, and nivolumab were superior to other treatments in NSCLC patients with liver metastases. These new findings may help clinicians better select therapeutic strategies for NSCLC patients with liver metastases.

Fermentation supernatant of Staphylococcus aureus drives catabolism in chondrocytes via NF-κB signaling mediated increase of cholesterol metabolism.

Septic arthritis induced by Staphylococcus aureus (S. aureus) causes irreversible cartilage degradation and subsequent permanent joint dysfunction. Recently, cartilage degradation in osteoarthritis is recognized to be associated with metabolic disorders. However, whether cholesterol metabolism is linked to septic arthritis pathology remains largely unknown. Here, we found that exposure to fermentation supernatant (FS) of S. aureus in chondrocytes resulted in a significant increase in expression of key modulators involved in cholesterol metabolism, including lectin-type oxidized low density lipoprotein receptor 1 (LOX1), cholesterol 25-hydroxylase (CH25H), 25- hydroxycholesterol 7α-hydroxylase (CYP7B1) as well as retinoic acid-related orphan receptor alpha (RORα), a binding receptor for cholesterol metabolites. We further demonstrated that enhancement of CH25H/CYP7B1/RORα axis resulted from FS exposure was mediated by activation of NF-κB signaling, along with upregulation in catabolic factors including matrix metallopeptidases (MMP3 and MMP13), aggrecanase-2 (ADAMTS5), and nitric oxide synthase-2 (NOS2) in chondrocytes. Exogenous cholesterol acts synergistically with FS in activating NF-κB pathway and increases cholesterol metabolism. While, the addition of tauroursodeoxycholic acid (TUDCA) which promotes cholesterol efflux, resulted in remarkable reduction of intracellular cholesterol level and restoration of balance between anabolism and catabolism in FS treated chondrocytes. Collectively, our data indicated that, in response to FS of S. aureus, NF-κB signaling activation coupled with increased cholesterol metabolism to stimulate catabolic factors in chondrocytes, highlighting cholesterol metabolism as a potential therapeutic target for treating septic arthritis.