Oridonin in combination with imatinib exerts synergetic anti-leukemia effect in Ph+ acute lymphoblastic leukemia cells in vitro by inhibiting activation of LYN/mTOR signaling pathway.

Abstract

Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) is triggered by constitutively activated BCR-ABL and SRC family tyrosine kinases.They account for the activations of multiple growth-signaling pathways, including Raf/MEK/ERK, Akt/mTOR and STAT5 pathways. The BCR-ABL tyrosine kinase inhibitor imatinib is the standard treatment for Ph+ leukemia and plays efficacious role in CML. However, imatinib has few inhibitory effects on SRC tyrosine kinase with response rate of Ph+ ALL lower and relapse more frequent and quicker compared with CML. Previous studies showed that oridonin inhibits proliferation and induces apoptosis in many tumor cells. However, the anticancer activity and mechanism of oridonin in Ph+ ALL is unknown. To investigate the anticancer activity of oridonin, we examined its role in constitutively activated Akt/mTOR, Raf/MEK/ERK, STAT5 and SRC pathway, mRNA level of bcr/abl gene, cell viability and apoptosis in Ph+ ALL SUP-B15 cells. Furthermore, we detected synergetic effect of oridonin plus imatinib. Our results showed that oridonin inhibiting activations of LYN (one of SRC family kinases) and ABL and their downstream Akt/mTOR, Raf/MEK/ERK and STAT5 pathways, downregulated Bcl-2 but upregulated Bax protein and then induced apoptosis in Ph+ ALL cells. Oridonin plus imatinib exerted synergetic effects by overcoming imatinib defect of upregulating Akt/mTOR and LYN signaling. Additionally, we examined the effect of oridonin on the signaling pathways in the primary specimens from Ph+ ALL patients. Our data showed that oridonin remarkably suppressed activations of Akt/mTOR, Raf/MEK and STAT5 pathway in these primary specimens and oridonin with imatinib exerted synergetic suppressive effects on mTOR, STAT5 and LYN signaling in one imatinib resistant patient specimen. Additional evaluation of oridonin as a potential therapeutic agent for Ph+ ALL seems warranted.

• Authors: Yong Guo, Qingqing Shan, Yuping Gong, Juan Lin, Xi Yang, Ruiqing Zhou
• Journal: Cancer biology & therapy (Cancer Biol Ther) Vol. 13 Issue 13 Pg. 1244-54 (Nov 2012) ISSN: 1555-8576 [Electronic] United States
• PMID: 22895079 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Benzamides
• Diterpenes, Kaurane
• Piperazines
• Protein Kinase Inhibitors
• Proto-Oncogene Proteins c-bcl-2
• Pyrimidines
• RNA, Messenger
• STAT5 Transcription Factor
• bcl-2-Associated X Protein
• oridonin
• Imatinib Mesylate
• MTOR protein, human
• Proto-Oncogene Proteins c-abl
• lyn protein-tyrosine kinase
• src-Family Kinases
• Proto-Oncogene Proteins c-akt
• TOR Serine-Threonine Kinases
• raf Kinases

Topics

• Antineoplastic Combined Chemotherapy Protocols (pharmacology)
• Apoptosis (drug effects, genetics)
• Benzamides (administration & dosage)
• Cell Proliferation (drug effects)
• Cell Survival (drug effects, genetics)
• Diterpenes, Kaurane (administration & dosage)
• Drug Synergism
• Humans
• Imatinib Mesylate
• Leukemia, Myelogenous, Chronic, BCR-ABL Positive (drug therapy, genetics, metabolism)
• MAP Kinase Signaling System (drug effects)
• Piperazines (administration & dosage)
• Precursor Cell Lymphoblastic Leukemia-Lymphoma (drug therapy, genetics, metabolism)
• Protein Kinase Inhibitors (pharmacology)
• Proto-Oncogene Proteins c-abl (genetics, metabolism)
• Proto-Oncogene Proteins c-akt (genetics, metabolism)
• Proto-Oncogene Proteins c-bcl-2 (genetics, metabolism)
• Pyrimidines (administration & dosage)
• RNA, Messenger (genetics)
• STAT5 Transcription Factor (genetics, metabolism)
• Signal Transduction (drug effects)
• TOR Serine-Threonine Kinases (antagonists & inhibitors, genetics, metabolism)
• Tumor Cells, Cultured
• bcl-2-Associated X Protein (genetics, metabolism)
• raf Kinases (genetics, metabolism)
• src-Family Kinases (antagonists & inhibitors, genetics, metabolism)