Ubiquitin ligase subunit FBXO9 inhibits V-ATPase assembly and impedes lung cancer metastasis.

BACKGROUND: The evolutionarily conserved protein FBXO9 acts as a substrate receptor for the SKP1-cullin-1-RBX1 ubiquitin ligase and is implicated in cancer, exhibiting either tumor-suppressive or oncogenic effects depending on the specific tumor type. However, their role in lung cancer metastasis remains unclear. METHODS: Lentiviral vectors carrying miRNA-based shRNA sequences for gene-specific knockdown were generated, and Lenti-CRISPR-Cas9 vectors containing gene-specific sgRNA sequences were designed. Gene overexpression was achieved using doxycycline-inducible lentiviral constructs, while gene knockdown or knockout cells were generated using shRNA and CRISPR-Cas9, respectively. Functional assays included migration, clonogenic survival assays, tumor sphere assays, and protein interaction studies using mass spectrometry, immunoprecipitation, and immunoblot analysis. RESULTS: This study identified FBXO9 as a crucial regulator that suppresses lung cancer cell migration, tumor sphere growth and restricts metastasis. We showed that FBXO9 facilitates the ubiquitination of the catalytic subunit A (ATP6V1A) of the Vacuolar-type H+-ATPase (V-ATPase), resulting in its interaction with the cytoplasmic chaperone HSPA8 and subsequent sequestration within the cytoplasm. This process hinders the assembly of functional V-ATPase, resulting in reduced vesicular acidification. In contrast, depletion of FBXO9 reduced ATP6V1A ubiquitination, resulting in increased V-ATPase assembly and vesicular acidification, thus promoting pro-metastatic Wnt signaling and metastasis of lung cancer cells. Furthermore, we demonstrated the effectiveness of inhibitors targeting V-ATPase in inhibiting lung cancer metastasis in a mouse model. Finally, we established a correlation between lower FBXO9 levels and poorer survival outcomes in patients with lung cancer. CONCLUSION: These findings collectively elucidate the critical role of FBXO9 in regulating V-ATPase assembly and provide a molecular basis for FBXO9's function in inhibiting lung cancer metastasis. This highlights the potential therapeutic opportunities of FBXO9 supplementation.

LINC01572 is a Novel Prognostic Biomarker and Therapeutic Target in Lung Adenocarcinoma.

BACKGROUND: Lung adenocarcinoma (LUAD) is one of the most common and lethal cancer types worldwide. LINC0572 is a long non-coding RNA (lncRNA) that has been associated with the clinical characteristics of several types of malignancy. However, the biological mechanism of LINC0572 in LUAD is still unclear and remains to be elucidated. METHODS: R packages and online bioinformatic tools were used to investigate the biological characteristics of LINC01572, including its abnormal expression, oncogenic role, and clinical prognostic value. In vitro and in vivo experiments were conducted to investigate the biological functions of LINC01572 in tumorigenesis and development. These included colony formation assays, cell migration assays, flow cytometry, cell counting kit-8 (CCK-8) cell proliferation and tumor transplant growth experiments. RESULTS: Bioinformatics results showed that LINC01572 was overexpressed in both LUAD and lung squamous cell carcinoma (LUSC) patients. LINC01572 overexpression was associated with shorter overall survival (OS) in LUAD. Further study of clinical specimens confirmed that LINC01572 was highly expressed in the tumor tissue of non-small cell lung cancer (NSCLC) patients. In vitro experiments also confirmed that LINC01572 was overexpressed in tumor cell lines. Inhibition of LINC01572 expression significantly impaired cell proliferation, cell migration, and clone formation. Experiments in nude mouse revealed that transplanted tumors with low expression of LINC01572 had significantly slower rates of growth in terms of volume and weight compared to the control group (p < 0.05). In addition, gene set enrichment analysis (GSEA) and immune landscape profiling showed that LINC01572 can promote tumor initiation and progression by deregulating the cell cycle and immunocyte infiltration. CONCLUSIONS: LINC01572 is overexpressed in tumor tissue relative to adjacent normal tissue. Moreover, LUAD patients with high expression of LINC01572 showed a worse survival prognosis. LINC01572 is associated with tumor initiation, progression and immune dysregulation. It therefore has potential value as a novel biomarker and therapeutic target in LUAD.

Anatomical change during radiotherapy for head and neck cancer, and its effect on delivered dose to the spinal cord.

BACKGROUND AND PURPOSE: The impact of weight loss and anatomical change during head and neck (H&N) radiotherapy on spinal cord dosimetry is poorly understood, limiting evidence-based adaptive management strategies. MATERIALS AND METHODS: 133 H&N patients treated with daily mega-voltage CT image-guidance (MVCT-IG) on TomoTherapy, were selected. Elastix software was used to deform planning scan SC contours to MVCT-IG scans, and accumulate dose. Planned (DP) and delivered (DA) spinal cord D2% (SCD2%) were compared. Univariate relationships between neck irradiation strategy (unilateral vs bilateral), T-stage, N-stage, weight loss, and changes in lateral separation (LND) and CT slice surface area (SSA) at C1 and the superior thyroid notch (TN), and ΔSCD2% [(DA - DP) D2%] were examined. RESULTS: The mean value for (DA - DP) D2% was -0.07 Gy (95%CI -0.28 to 0.14, range -5.7 Gy to 3.8 Gy), and the mean absolute difference between DP and DA (independent of difference direction) was 0.9 Gy (95%CI 0.76-1.04 Gy). Neck treatment strategy (p = 0.39) and T-stage (p = 0.56) did not affect ΔSCD2%. Borderline significance (p = 0.09) was seen for higher N-stage (N2-3) and higher ΔSCD2%. Mean reductions in anatomical metrics were substantial: weight loss 6.8 kg; C1LND 12.9 mm; C1SSA 12.1 cm2; TNLND 5.3 mm; TNSSA 11.2 cm2, but no relationship between weight loss or anatomical change and ΔSCD2% was observed (all r2 < 0.1). CONCLUSIONS: Differences between delivered and planned spinal cord D2% are small in patients treated with daily IG. Even patients experiencing substantial weight loss or anatomical change during treatment do not require adaptive replanning for spinal cord safety.