Bystin-like protein forms a functional complex with DDX49 to enhance thyroid cancer progression.

The incidence of thyroid cancer is rising worldwide, underscoring the urgent need for novel molecular targets in the management of aggressive disease. This study identifies bystin-like protein (BYSL) as a previously unrecognized oncogenic driver in thyroid carcinoma. Comprehensive analyses of clinical specimens, established cell lines, and patient-derived tumor-like clusters revealed that BYSL is significantly upregulated in thyroid malignancies and is strongly correlated with adverse patient outcomes. Functional assays demonstrated that BYSL promotes tumor cell proliferation, migration, and invasion while suppressing apoptosis. Mechanistically, BYSL interacts directly with DEAD-box helicase 49 (DDX49) to form a functional protein complex that impairs the biogenesis of the tumor suppressor miR-145-5p by inhibiting its DICER-mediated processing. Dual knockdown of BYSL and DDX49 synergistically suppressed tumor growth and induced apoptosis in patient-derived tumor-like cell clusters, with these effects reversed by inhibition of miR-145-5p. Collectively, these findings demonstrate the BYSL-DDX49 complex as a pivotal modulator of thyroid cancer progression and underscore its promise as a therapeutic intervention for restoring tumor-suppressive pathways.