Knockdown of protein phosphatase 5 (PPP5C) suppresses the growth of leukemic cell line U937.

Serine/threonine protein phosphatase 5 (PPP5C) participates in multiple signaling pathways including cell cycle control and cell growth. PPP5C is involved in the progression of human breast cancer and hepatocellular carcinoma. However, its function in acute myelogenous leukemia (AML) remains unknown. In this study, we constructed a lentivirus system to knock down the expression level of PPP5C in leukemic cell line U937. Cell proliferation and cell cycles were assessed by MTT assay and flow cytometry respectively. Western blot was used to determine the level of caspase-3, PARP (poly ADP-ribose polymerase), CDK4 and CyclinD1. Knockdown of PPP5C suppressed the proliferation ability of U937 cells, and led to G0/G1 phase arrest, inducing cell apoptosis in U937 cells. The apoptosis of the U937 cells was associated with upregulating cleaved caspase-3 and PARP, and downregulating CDK4 and CyclinD1. In conclusions, PPP5C knockdown inhibits U937 cell proliferation and might be used as a potential therapeutic target for the treatment of leukemia.

[A multicenter, prospective, phaseâ ¡, single-arm study on the treatment of newly diagnosed multiple myeloma with domestic bortezomib in combination with lenalidomide and dexamethasone].

Objective: To explore the efficacy and safety of domestic bortezomib in combination with lenalidomide and dexamethasone in the treatment of newly diagnosed multiple myeloma (NDMM) . Methods: This multicenter, prospective, single-arm clinical study included 126 patients with NDMM admitted to seven hospitals between December 2019 and January 2022. All patients received domestic bortezomib in combination with lenalidomide and dexamethasone (BLD regimen), and the efficacy, prognostic factors, and safety were analyzed. Results: Among the 126 patients with NDMM, 118 completed four cycles of treatment, with an overall response rate (ORR) of 93.22% (110/118) and a ≥very good partial response (VGPR) rate of 68.64% (81/118). Ultimately, 114 patients completed at least eight cycles of treatment, with an ORR of 92.98% (106/114) and a ≥VGPR rate of 77.19% (88/114). Eighteen patients underwent autologous hematopoietic stem cell transplantation after completing 6-8 cycles of the BLD regimen, with an ORR of 100% (18/18) and a ≥VGPR rate of 88.9% (16/18). The proportion of patients achieving ≥VGPR increased with the treatment duration, and factors such as staging and age did not significantly affect efficacy. Single-factor analysis showed that R2-ISS stage Ⅲ/Ⅳ, blood calcium >2.27 mmol/L, and failure to achieve VGPR after six cycles were adverse prognostic factors for progression-free survival (PFS) (P<0.05), whereas failure to achieve VGPR after six cycles was an adverse prognostic factor for overall survival (OS) (P<0.001). Multifactor analysis demonstrated that failure to achieve VGPR after six cycles is an independent adverse prognostic factor for PFS (P=0.002). The incidence of hematologic adverse reactions was 16.7% (19/114), and nonhematologic adverse reactions were mainly mild to moderate, with no significant cardiac or renal adverse reactions observed. Conclusion: The BLD regimen is effective in treating NDMM, in which patients with high-risk genetic features are still achieving a high ≥VGPR rate, and the overall safety is good.