PPM1D Knockdown Suppresses Cell Proliferation, Promotes Cell Apoptosis, and Activates p38 MAPK/p53 Signaling Pathway in Acute Myeloid Leukemia

Abstract

Objectives: This study was to explore the effect of protein phosphatase, Mg²⁺/Mn²⁺ dependent 1D knockdown on proliferation and apoptosis as well as p38 MAPK/p53 signaling pathway in acute myeloid leukemia.

Methods: The expression of protein phosphatase, Mg²⁺/Mn²⁺ dependent 1D was detected in acute myeloid leukemia cell lines including SKM-1, KG-1, AML-193, and THP-1 cells, and normal bone marrow mononuclear cells isolated from healthy donors. The knockdown of protein phosphatase, Mg²⁺/Mn²⁺ dependent 1D was conducted by transfecting small interfering RNA into AML-193 cells and KG-1 cells.

Results: The relative messenger RNA/protein expressions of protein phosphatase, Mg²⁺/Mn²⁺ dependent 1D were higher in SKM-1, KG-1, AML-193, and THP-1 cells compared with control cells (normal bone marrow mononuclear cells). After transfecting protein phosphatase, Mg²⁺/Mn²⁺ dependent 1D small interfering RNA into AML-193 cells and KG-1 cells, both messenger RNA and protein expressions of protein phosphatase, Mg²⁺/Mn²⁺ dependent 1D were significantly reduced, indicating the successful transfection. Most importantly, knockdown of protein phosphatase, Mg²⁺/Mn²⁺ dependent 1D suppressed cell proliferation and promoted cell apoptosis in AML-193 cells and KG-1 cells. In addition, knockdown of protein phosphatase, Mg²⁺/Mn²⁺ dependent 1D enhanced the expressions of p-p38 and p53 in AML-193 cells and KG-1 cells. The above observation suggested that protein phosphatase, Mg²⁺/Mn²⁺ dependent 1D knockdown suppressed cell proliferation, promoted cell apoptosis, and activated p38 MAPK/p53 signaling pathway in acute myeloid leukemia cells.

Conclusion: Protein phosphatase, Mg²⁺/Mn²⁺ dependent 1D is implicated in acute myeloid leukemia carcinogenesis, which illuminates its potential role as a treatment target for acute myeloid leukemia.

Keywords: AML; PPM1D; apoptosis; p38 MAPK/p53 signaling pathway; proliferation.

Figure 1.

Comparison of PPM1D expression between AML cell lines and control cells. Comparison of PPM1D mRNA expression (A) and protein expression (B and C) between AML cell lines and normal BMMCs. AML indicates acute myeloid leukemia; BMMCs, bone marrow mononuclear cells; mRNA, messenger RNA; PPM1D, protein phosphatase, Mg²⁺/Mn²⁺ dependent 1D.

Figure 2.

PPM1D silencing suppressed cell proliferation in AML cells. The mRNA and protein expression of PPM1D after transfection in AML-193 cells (A-C). Cell proliferation after transfection in AML-193 cells (D). The mRNA and protein expression of PPM1D after transfection in KG-1 cells (E-G). Cell proliferation after transfection in KG-1 cells (H). AML indicates acute myeloid leukemia; mRNA, messenger RNA; PPM1D, protein phosphatase, Mg²⁺/Mn²⁺ dependent 1D.

Figure 3.

PPM1D silencing caused cell cycle arrest. Cell cycle after transfection in aml-193 cells (A and B) and KG-1 cells (C and D). PPM1D indicates protein phosphatase, Mg²⁺/Mn²⁺ dependent 1D.

Figure 4.

PPM1D silencing promoted cell apoptosis in AML cells. The cell apoptosis rate after transfection in AML-193 cells (A and B) and KG-1 cells (C and D). AML indicates acute myeloid leukemia; PPM1D, protein phosphatase, Mg²⁺/Mn²⁺ dependent 1D.

Figure 5.

PPM1D silencing activated p38 MAPK/p53 pathway in AML cells. The relative expression of p-p38, p-p53, and the target gene of p38 (p-ATF2), as well as target gene of p53 (Bax) in AML-193 cells (A and B) and KG-1 cells (C and D). AML indicates acute myeloid leukemia; PPM1D, protein phosphatase, Mg²⁺/Mn²⁺ dependent 1D.