LAMP3 plays an oncogenic role in osteosarcoma cells partially by inhibiting TP53.

Background: Osteosarcoma (OS) is a common malignant tumor that predominantly occurs in adolescents. Its most common metastasis is to the lungs. As shown in our earlier study, lysosome-associated membrane glycoprotein 3 (LAMP3) is highly upregulated in metastatic OS. However, its role in the regulation of OS cell viability and apoptosis remains unknown.

Methods: We knocked down and overexpressed LAMP3 in OS cells and assessed the cell viability and apoptosis. Then, we investigated the expression of apoptosis-associated genes to identify the downstream gene(s) of LAMP3 .

Results: Knockdown of LAMP3 significantly inhibited OS cell viability and promoted apoptosis. TP53 , which is involved in the apoptosis pathway, was found to be highly upregulated after knockdown of LAMP3 . Overexpression of LAMP3 significantly increased cell viability and abrogated apoptosis. Importantly, subsequent knockdown of TP53 partially suppressed the increased OS cell apoptosis induced by the inhibition of LAMP3 , suggesting that TP53 is a key functional downstream gene of LAMP3 .

Conclusions: Our findings suggest that LAMP3 promotes OS cell viability and survival by regulating TP53 expression.