PMA exerts anti-leukemia effect in Ph+ ALL through activating PKC δ and its down-stream molecules.

Background: Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph⁺ ALL) is a subtype of precursor B ALL in genetics and is recognized as a subclass with poor prognosis. Tyrosine kinase inhibitors (TKIs) greatly improve the prognosis of Ph⁺ ALL patients. However, the long-term survival rate is still low (with a 3-year survival rate only 55%). Hence, it is urgent to explore new therapies to improve prognosis for Ph⁺ ALL patients. Protein kinase C (PKC) is proven to be a tumor suppressor in recent years. Activation of PKC by its novel agonist PMA reverts the malignancy of many hematological diseases. However, the effect of PMA on Ph⁺ ALL is unclear.

Methods: We investigated the biological effects of PMA on Ph⁺ ALL cells and the potential mechanism in this study. In this study, the SUP-B15 and BP190 cell lines were subjected to PMA treatment. Cell proliferation, cycle distribution, apoptosis, protein expression levels, and gene expression changes were assessed using CCK-8 assay, flow cytometry, Western blot analysis, DAPI staining, and quantitative real-time PCR. Additionally, bone marrow mononuclear cells were isolated for further investigation, and RNA sequencing was conducted on SUP-B15 cells. Furthermore, the mouse model was established to evaluate the in vivo biological effects of PMA.

Results: We found that PMA could promote apoptosis, inhibit proliferation and promote differentiation of human Ph⁺ ALL cells. More importantly, we demonstrated for the first time that these effects caused by PMA were related to the activation of PKC δ and its down-stream molecules, such as p-ERK, p21 and so on.

Conclusions: PMA exerts an anti-leukemia effect in Ph⁺ ALL by activating PKC δ and its downstream molecules, thereby demonstrating its potential as a therapeutic agent for Ph⁺ ALL.