Phosphodiesterase 3A Acts As a Tumor Activator and Its Inhibitor Anagrelide Combined with Idarubicin Represents a Potential Therapeutic Approach for PDE3A High Expressed Acute Myeloid Leukemia through Pyroptosis By Triggering Cleavage of Gasdermin E

Acute myeloid leukemia (AML) is a clinically aggressive and heterogeneous hematologic neoplasm with a poor overall outcome. Platelets can interact with malignant cells including leukemic blasts and play a crucial role in cancer progression, metastasis and angiogenesis, budding of platelet microparticles can transfer a plethora of bioactive molecules to cancer cells upon internalization and in AML this can induce chemoresistance. Anti-platelet therapy using Phosphodiesterase 3A (PDE3A) inhibitors, such as anagrelide (ANA), holds promise in tumor elimination. Additionally, upregulation of PDE3A in solid tumors is associated with a poor prognosis in patients and activates inflammatory pathways, impacting cancer cell stemness. However, the role of PDE3A in AML remains unclear. This study aims to investigate the correlation between PDE3A expression and AML prognosis, as well as to characterize the feasibility and mechanism of ANA as a potential anti-leukemia therapy and its synergistic effect to chemotherapeutic drugs.

To explore the correlation between PDE3A expression and AML prognosis, we initially analyzed its expression in AML patients and healthy donors from the Children's Hospital of Soochow University. The results demonstrated significantly higher levels of PDE3A in bone marrow mononuclear cells (BMMNCs) from AML patients, both at the protein and mRNA levels, compared to BMMNCs from healthy donors. Subsequently, we investigated PDE3A expression and survival data of 152 AML patients from our center, revealing that patients with high PDE3A expression exhibited significantly lower overall survival (OS), relapse-free survival (RFS), and event-free survival (EFS) compared to those with low PDE3A expression. These findings were further corroborated by data from other databases (R2 and GEPIA), confirming the significant role of PDE3A in AML.

Among AML cell lines, HEL and MOLM-16 cells exhibited notably higher PDE3A expression at both the protein and mRNA levels, which were chosen for further study. ANA treatment specifically inhibited the proliferation of PDE3A-high-expressing AML cells but not low expression cells in vitro, which was further confirmed in the HEL-mediated xenograft leukemia model. Notably, the RNA sequencing data revealed ANA treatment significantly downregulated several chemotherapy-resistant genes, including PAK1, HMGCS1, p-SRC, DUSP16 and EGR1, indicating ANA has the potential to synergize with chemotherapeutic drugs for AML therapy. Therefore, we combine ANA and chemotherapy drugs to investigate the synergetic inhibitory effect. IDA with ANA simultaneously exerted the strongest synergistic effect among the six anti-leukemia drugs depend on the judgement of CI value and had the synergistic effect in HEL, MOLM-16 and primary cells from PDE3A high expressed AML patients. The GSEA analysis of RNA sequencing data showed that the IDA-ANA combination treatment led to a significant enrichment of the inflammatory response. Moreover, at the protein level, pyroptosis-related proteins including NLRP3, Cleaved-CASP3, Cleaved-CASP8 and GSDME-N were notably upregulated in IDA-ANA combination group compared to IDA or ANA group. Finally, we established an AML xenograft mouse model using the HEL cell line and administered different treatments: vehicle (control), IDA (0.5 mg/kg), ANA (5 mg/kg), or the indicated combination of IDA and ANA. The results demonstrated that the IDA-ANA combination treatment significantly extended the survival time of the mice and reduced the leukemia burden when compared to the individual treatments with either IDA or ANA. In second HEL xenograft mice study, separate cohorts of vehicle and drug treated mice were sacrificed and leukemic livers as well as spleens were harvested and weighed, the IDA-ANA combination treated mice exhibited smaller and lighter livers and spleens than the other groups and controls. HE results explained the histological decrease of HEL cells infiltration of IDA-ANA combination treatment in the livers, spleens and bone marrow compared with the treatment of IDA or ANA. Congruently, the analysis of IHC confirmed the same result.

In summary, high expression of PDE3A related to poor prognosis in AML and PDE3A inhibitor ANA combined with IDA exerted anti-leukemia effect through pyroptosis on PDE3A high expressed AML. Our findings represent a potential therapeutic regimen for AML.