(P 72) CO-EXPRESSION OF LEUKOCYTE CYTOSOLIC PROTEIN 1 AND MATRIX METALLOPROTEINASES ARE INTEGRAL FOR METASTATIC PROGRESSION OF CHONDROSARCOMA

Objective: As chondrosarcoma (CSA) lacks effective systemic therapies for metastatic disease, identifying novel targets remains necessary. Our previous work identified overexpression of Leukocyte Cytosolic Protein 1 (LCP1) in metastasizing CSAs and that increased expression of LCP1 directly increases migration and invasiveness in CSA. Further, as LCP1 has been shown to correlate with matrix metalloproteinases activity and extracellular matrix degradation in non-CSA tumors, we therefore hypothesize that LCP1 with MMPs are integral to the metastatic potential of CSA.

Methods: Four primary CSA tumors were used in this study, two from metastasizing tumors (725, 731) and two from non-metastasizing tumors (732, 743). Previous studies confirmed high native expression of LCP1 in the metastasizing tumors and low expression in the non-metastasizing tumors. Their conditional knockout and overexpression conditions were generated and confirmed via western blotting. Bulk RNA sequencing data and protein quantification via Luminex assay were performed to measure expression of MMP-1 and MMP-9. Hydrogel matrices were generated to recapitulate a 3D environment. Protein localization was demonstrated with immunocytochemistry.

Results: Bulk RNA sequencing with comparison of non-metastasizing and metastasizing cell lines, as expressed by Log 2-fold change, revealed overexpression of MMP-1 (p < 0.001) and MMP-9 (p < 0.01) in LCP1 high metastasizing tumors. Excreted MMP-1 and MMP-9 protein expression from 3D hydrogel matrices were significantly higher in the LCP1 high metastasizing compared to the LCP1 low non-metastasizing cell lines. Immunocytochemistry of the 3D hydrogel matrices demonstrated co-localization of MMPs at the invadopodia edge in LCP1 high metastasizing cell lines.

Conclusion: Our findings suggest that while LCP1 directly contributes to cell motility and invasiveness in CSA, this effect may be further mediated by increased co-expression of MMP-1 and MMP-9. Our findings suggest common regulatory machinery for the expression of LCP1 , MMP-1 and MMP-9, as well as potential for targeted agents with multiple therapeutic effects that we continue to investigate.