E2F1 rs3213150 polymorphism influences cytarabine sensitivity and prognosis in patients with acute myeloid leukemia

Cytarabine (Ara-C) plays an irreplaceable role in the treatment of acute myeloid leukemia (AML). However, there are significant differences in efficacy among patients. Our previous studies found that E2F1 rs3213150 polymorphism was associated with remission rate of Ara-C chemotherapy, but the specific mechanism is not clear. This study aimed to further confirm the correlation between E2F1 rs3213150 polymorphism and Ara-C resistance and prognosis in AML patients, and to provide valuable information for elucidating the molecular mechanisms involved.

METHODS

Rs3213150 genotyping was performed in 922 AML patients by Sanger sequencing, and the effects of different genotypes on chemosensitivity and prognosis were analyzed by Logistic regression and Cox regression. Meanwhile, a prediction model of Ara-C chemotherapy resistance was established. The impact of rs3213150 polymorphism on E2F1 expression level was determined by luciferase reporter gene assay, and differentially expressed genes between patients with different genotypes were identified by RNA sequencing.

RESULTS

Compared with rs3213150 G allele carriers, patients with AA genotype had more obvious Ara-C resistance (41.94% vs. 27.94%, P = 0.002), shorter overall survival (529 d vs. 644 d, P = 0.008) and disease-free survival (519 d vs. 556 d, P = 0.023). Rs3213150G > A mutation resulted in decreased E2F1 expression.

CONCLUSION

E2F1 rs3213150 polymorphism influences the chemosensitivity and prognosis of Ara-C in Chinese AML patients.

Gene therapy with E2F-1 up-regulates the protein kinase PKR and inhibits growth of leiomyosarcoma in vivo

Overexpression of the transcription factor E2F-1 induces apoptosis in a variety of carcinoma cells and inactivates murine double minute protein 2, a factor associated with poor prognosis in soft tissue sarcomas. We have shown previously that the double-stranded RNA-activated protein kinase PKR plays an important role in mediating this apoptotic response in carcinoma cells to E2F-1. We sought to evaluate the potential of E2F-1 gene therapy in soft tissue sarcomas and to study the involvement of PKR in the response to E2F-1 overexpression in mesenchymal cells. A replication-deficient adenovirus carrying the E2F-1 gene (Ad5E2F) was used to induce E2F-1 overexpression in the p53 mutated leiomyosarcoma cell line, SKLMS-1. Western blot analysis confirmed E2F-1 overexpression and up-regulation of the antiapoptotic factor Bcl-2 48 hours following infection with Ad5E2F. Apoptosis in Ad5E2F-treated cells was confirmed by fluorescence-activated cell sorting analysis and by poly(ADP-ribose) polymerase cleavage and DNA fragmentation assays. Vector-dependent up-regulation of PKR correlated with the amount of Ad5E2F-induced apoptosis. In vivo treatment of SKLMS-1 tumor-bearing BALB/c mice with intratumoral injections of Ad5E2F at a dose of 2 x 10(10) viral particles resulted in significant inhibition in tumor growth compared with control-treated animals (P < 0.016). Complete disappearance of all tumors was seen in two of seven mice in the Ad5E2F-treated animals. Immunohistochemical analysis of tumor specimens showed overexpression of E2F-1 and up-regulation of PKR in Ad5E2F-treated tumors. These findings show that adenovirus-mediated overexpression of E2F-1 results in up-regulation of PKR and significant growth suppression of leiomyosarcomas in vivo. Taken together, these data suggest that E2F-1 gene therapy and PKR modulation might be a promising treatment strategy for these tumors that are highly resistant to conventional therapies.