The cotranslational misfolding of the cystic fibrosis transmembrane conductance regulator chloride channel (CFTR) plays a central role in the molecular basis of cystic fibrosis (CF). The misfolding of the most common CF variant (ΔF508) remodels both the translational regulation and quality control of CFTR. Nevertheless, it is unclear how the misassembly of the nascent polypeptide may directly influence the activity of the translation machinery. In this work, we identify a structural motif within the CFTR transcript that stimulates efficient -1 ribosomal frameshifting and triggers the premature termination of translation. Though this motif does not appear to impact the interactome of wild-type CFTR, silent mutations that disrupt this RNA structure alter the association of nascent ΔF508 CFTR with numerous translation and quality control proteins. Moreover, disrupting this RNA structure enhances the functional gating of the ΔF508 CFTR channel at the plasma membrane and its pharmacological rescue by the CFTR modulators contained in the CF drug Trikafta. The effects of the RNA structure on ΔF508 CFTR appear to be attenuated in the absence of the ER membrane protein complex (EMC), which was previously found to modulate ribosome collisions during "preemptive quality control" of a misfolded CFTR homolog. Together, our results reveal that ribosomal frameshifting selectively modulates the assembly, function, and pharmacological rescue of a misfolded CFTR variant. These findings suggest interactions between the nascent chain, quality control machinery, and ribosome may dynamically modulate ribosomal frameshifting in order to tune the processivity of translation in response to cotranslational misfolding.

Background/Objective: Cachexia is a systemic wasting syndrome characterized by skeletal muscle mass loss and is estimated to affect 80% of lung cancer patients. Previous studies haveshown that metastatic bone disease may have a role in inducing cachexia, which is mediated bycytokines such as IL-6, TNF-α, and TGF-β. To develop therapies for cachexia, a better understanding of the impact of metastatic bone disease and these cytokines on cachexia is needed. Methods: Patients diagnosed with lung cancer were identified from an institutional database and were designated to one of three cohorts: local disease (n=63), osseous metastatic disease(n=39), and extraosseous metastatic disease (n=39). Body mass index (BMI) at diagnosis and follow up were collected. Change in BMI per year was calculated and the Kruskal-Wallis Test was used to compare groups. In a parallel study, ELISA was performed for IL-6, TNF-α, and TGF-β on supernatant collected after 48 hours from the cell lines BEAS-2B (normal lung epithelia), H1299 (lung cancer), and A549 (lung cancer). These groups were compared using a one-way ANOVA. Results: Median change in BMI was not statistically different (P=.79) among any cohort. The cytokine level varied by cell line. H1299 had significantly increased levels of TGF-β as compared to BEAS-2B (P=.004). A549 had elevated, but not a statistically significant differentlevel of IL-6 as compared to BEAS-2B (P=.17). TNF-α was not present in any cell line. Conclusion:BMI was not associated with disease state with the numbers available. The parallel study showed cell line specific elevation of TGF-β and IL-6 in lung cancer compared to noncancerous tissues. Together, these findings are inconclusive but support continued investigation into the pathogenesis of cachexia in lung cancer. Future studies will employ imaging-based body composition measurements in these disease cohorts and explore int eractions between tumor, bone, and muscle in vitro.

Background Many cancers metastasize to bone and may lead to pathologic fracture or impending pathologic fracture. Prophylactically stabilizing bones before fracture has been shown to be more cost-effective with improved outcomes. Many studies have examined risk factors for pathological fracture, with radiographic and functional pain data serving as predominant indicators for surgery. Conditions associated with poor bone health and increased risk of fracture in the non-oncologic population, including diabetes mellitus, chronic obstructive pulmonary disease (COPD), cardiovascular disease, renal disease, smoking, corticosteroid use, and osteoporosis, have not been studied in the context of metastatic disease. Characterization of these factors could help providers identify candidates for prophylactic stabilization thereby reducing the number of completed pathological fractures. Methods 298 patients over the age of 40 with metastatic bone disease of the femur treated between 2010-2021 were retrospectively identified. Patients without complete medical documentation or with non-metastatic diagnoses were excluded. 186 patients met inclusion and exclusion criteria, including 74 patients who presented with pathological femur fracture and 112 patients who presented for prophylactic stabilization. Patient demographics and comorbidities including diabetes mellitus, COPD, cardiovascular disease, renal disease, osteoporosis, active tobacco or corticosteroid use, and use of anti-resorptive therapy were collected. Descriptive statistics were compiled, with univariable analysis by Mann-Whitney or chisquared testing. Multiple logistic regression was then performed to identify the most significant patient variables for presenting with completed fracture. Results On univariable analysis, patients with COPD were more likely to present with pathologic fracture (19/32 [59%] compared to 55/154 [36%], p = 0.02). A trend emerged for patients with an increasing number of comorbidities (28/55 [51%] for 2+ comorbidities compared to 18/61 [29%] with zero comorbidities, p = 0.06). On multivariable analysis, patients with two or more comorbidities (OR: 2.49; p=0.02) were more likely to present with a femur fracture. Conclusion This analysis suggests that those with an increasing number of comorbidities may be at increased risk for pathologic fracture. This study raises the possibility that patient factors and/ or comorbidities alter bone strength and/or pain experiences and may guide orthopaedic oncologists weighing prophylactic stabilization of femur lesions. Level of Evidence: III.

The overall prognosis for solid tumors overexpressing mesenchymal‐epithelial transition factor (cMET) receptor tyrosine kinase and NADPH:Quinone oxidoreductase 1 (NQO1) is poor, and innovative treatment strategies that selectively target these cancers are critically needed. Recent studies have implicated cMET in the activation of PARP1, a critical factor involved in DNA damage response and repair. Therefore, targeting cMET is an attractive strategy for cancer therapy. However, the overall efficacies of cMET inhibitors and NQO1 bioactivable agents are limited due to dose‐limiting toxicities and lack of tumor selectivity at high concentrations as a monotherapy. Here, we report that the combination treatment with sublethal doses of cMET inhibitors (some in clinical trials and FDA‐approved) and β‐lapachone (β‐lap, an NQO1‐bioactivatable drug in clinical trials) induced synergistic lethality in cancer cells in an NQO1‐dependent manner. Mechanistically, a sublethal dose of β‐lap creates reactive oxygen species (ROS) that damage DNA nucleobases (e.g., 8‐oxoguanine) but rapidly gets repaired by the ability of ROS‐activated cMET to enhance PARP1 activity for efficient DNA damage repair in NQO1+ cells. Thus, β‐lap in combination with cMET inhibition elevated DNA damage by compromising DNA repair, increased double‐strand break (DSB) formation and promoted tumor selective apoptosis in NQO1+cancer cells. We further determined that the combination treatment significantly inhibit tumor growth in 3D spheroids. Our results add a new strategy for personalized therapy: the targeting of cMET in NQO1+ cancers to potentiate the toxic effects of sub‐lethal doses of NQO1‐bioativatable agents and cMET inhibitors.