TGFβ‐Mediated Overexpression of Podoplanin Serves as a Potential Diagnostic Biomarker in Acute Promyelocytic Leukemia

Early diagnosis of acute promyelocytic leukemia (APL), driven by PML‐RARA oncoprotein, is vital for survival, as delays can cause fatal coagulopathy without prompt therapeutic intervention of all‐trans retinoic acid and arsenic trioxide. Although APL is diagnosed using microscopy, immunophenotyping, and FISH/PCR for PML‐RARA, morphological overlap with acute myeloid leukemia (AML) ‐M5 and AML‐M2 complicates identification. In resource‐limited settings, unavailability of real time ‐quantitiative PCR (RQ‐PCR) or delays in FISH/qualitative RT‐PCR results increase the risk of missed or late diagnosis with fatal outcomes. Podoplanin (PDPN), a glycoprotein overexpressed in APL cells, interacts with platelets to mediate thrombosis. We evaluated PDPN expression, regulation, and diagnostic potential in APL. PDPN mRNA (RQ‐PCR) and surface protein (flow cytometry) were significantly higher in APL than non‐APL AML ( p < 0.0001), consistent with TCGA‐LAML and BEATAML1.0 datasets. Sensitivity and specificity were 80.7% and 71.43% by RQ‐PCR, and 92.86% and 100% by flow cytometry, respectively. Chromatin immunoprecipitation followed by quantitative PCR (ChIP‐qPCR) and TGF‐ β1 stimulation confirmed SMAD binding and PDPN upregulation. Pharmacological inhibition of TGF‐β1 ligand using luspatercept reduced SMAD phosphorylation and PDPN expression, indicating TGF‐β/SMAD transcriptionally regulates PDPN. Additionally, ELISA‐based serum profiling showed significantly elevated TGF‐β1 levels in APL patients compared to non‐APL AML ( p < 0.0001). These findings identify PDPN overexpression as a downstream consequence of TGF‐β/SMAD signaling and highlight its potential as a diagnostic biomarker for APL.