Childhood Cancer Data Initiative Annual Symposium (Abstract Registration): Submission #66

Abstract Submission for Poster Presentation
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Abstract Title:: Repurposing Anti-Fibrotic Strategies to Target Type II Pneumocyte-Driven Osteosarcoma Metastatic Progression
Abstract::
Pulmonary metastasis is the leading cause of mortality in human and canine osteosarcoma (OS) patients, yet the contribution of lung-resident type II pneumocytes (TIIPs) to metastatic progression is under-defined. This study characterizes the distribution of pneumocytes in the OS lung metastasis microenvironment, defines the consequences of TIIP-OS crosstalk, and identifies a therapeutic strategy to limit pulmonary metastatic progression. Spatial transcriptomics and complementary IHC staining of human, canine, and murine OS lung metastases showed increased TIIP accumulation at the tumor:non-tumor interface compared to distal lung parenchyma. Indirect co-culture of human primary TIIPs with MG63.2 OS cells significantly increased tumor cell proliferation, an effect reproduced with TIIP-conditioned media, suggesting that soluble TIIP-derived factors are pro-tumorigenic. RNA sequencing of co-cultured TIIPs showed enrichment of the p53 pathway, consistent with an injury/stress response resembling idiopathic pulmonary fibrosis. Cytokine profiling and Enrichr pathway analysis identified a pro-fibrotic secretome as a dominant feature of TIIP-OS crosstalk. Targeting TGF-β-mediated fibrosis with a dual integrin inhibitor reduced K7M2 OS proliferation in TIIP co-culture but not in monoculture, suggesting that the anti-proliferative effect is mediated through disruption of TIIP-OS crosstalk. A K7M2-pEGFP experimental metastasis model treated with 5 mg/kg or 25 mg/kg inhibitor showed significant dose-dependent reductions in metastases versus vehicle control. These findings provide the first cross-species characterization of TIIP spatial distribution within the OS pulmonary metastatic niche, demonstrating that TIIPs establish a growth-permissive, pro-fibrotic crosstalk with tumor cells. Disrupting this crosstalk represents a promising therapeutic strategy to limit metastatic progression and improve survival outcomes for OS patients.

Authors::
1. First Name: Janice
   Middle Initial: S
   Last Name: Pereira
   Degree(s): Ph.D
   Organization: NCI, NIH
2. First Name: Lauren
   Middle Initial: E
   Last Name: McGee
   Degree(s): Ph.D
   Organization: NCI, NIH
3. First Name: Anjali
   Last Name: Garg
   Degree(s): Ph.D
   Organization: NCI, NIH
4. First Name: Kate
   Middle Initial: I
   Last Name: Silver
   Degree(s): BS
   Organization: NCI, NIH
5. First Name: Troy
   Middle Initial: A
   Last Name: McEachron
   Degree(s): Ph.D
   Organization: NCI, NIH
6. First Name: Christina
   Last Name: Mazcko
   Degree(s): BS
   Organization: NCI, NIH
7. First Name: Jessica
   Middle Initial: A
   Last Name: Beck
   Degree(s): DVM Ph.D DACVP
   Organization: NCI, NIH and OSU
8. First Name: Amy
   Middle Initial: K
   Last Name: LeBlanc
   Degree(s): DVM
   Organization: NCi, NIH

Presenting Author:: Janice S. Pereira
Institution:: NCI, NIH
Email Address:: janice.pereira@nih.gov