The Study Of Toll Like Receptor In Acute Myeloid Leukemia

Background:Toll-like receptors (TLRs) are major agents of innate immunity and initiators of adaptive immunity, involved in the activation of tumors. They are pattern recognition receptors (PRP) recognizing pathogens via pathogen-specific molecular patterns (PAMPs), Although mRNAs derived from TLR genes have been reported in B-cells from lymphoproliferative disorders, the expression and functionality of TLR on acute promyelocytic leukemia cells has seldom been investigated. However, such structures could provide an interesting therapeutic target if they are functional and their triggering induces relevant modifications of tumor cells. Such approaches could be proposed for second-line therapy in acute myeloid leukemia patients who harbour minimal residual disease after achieving complete remission. We examined the expression of TLR7 and TLR9 genes in normal and AML-cells. Then since imidazoquinolines have been described in the literature as TLR7 agonist, the imidazoquinoline-like molecule, imiquimod R837 was used to engage TLR7 on HL60 cells, which is the model of acute myeloid leukemia in vitro.Objective:The aim of study was to explore the potential application of targeting at Toll-like receptors (TLRs) in the immunotherapy of acute myeloid leukemia, to investigate the expression of mRNAs derived from on primary acute myeloid leukemia (AML), and the effects of TLR 7 agonist Imiquimod on proliferation, apoptosis of HL60 cells.Methods:(1)Reverse trascripse Polymerase chain reaction(RT-PCR)was used to detect the level of TLR7 and TLR9 gene mRNA expression in 16 primary acute myeloid leukemia (AML) patients and 16 normal cases,β-actin as contrast.'(2)The effect of TLR 7 agonist, imiquimod, on HL60 cells prolife ration was evaluated by MTT, apoptosis were detected by flow cytometry (FCM).Results:(1)The level of TLR-7/β-actin mRNA expression was 1.4364±0.1701 in 16 primary acute myeloid leukemia patients and 1.3295±0.0692 in 16 normal cases, there was significantly statistic difference between these two groups (P<0.05).The level of TLR-9/β-actin mRNA expression was 1.5094±0.1886 in 16 primary acute myeloid leukemia patients and 1.4090±0.1160 in 16 normal cases, there was no significantly statistic difference between these two groups (P>0.05)(2) The inhibition rate was elevated by MTT, After being treated with TLR7 agonist imiquimod (5μg/ml), Ara-C (2μM) and Combined with both,the percentage of inhibition rate was 61%,63% and 55% after being treated 48 hours, and 54%,71%,and 75% after being treated72 hour. The rate of apoptosis was analyzed by cell quest, after treatment with TLR7 agonist imiquimod (5μg/ml), Ara-C (2UM) and Combined with both, the percentage of apoptosis rate was 39.33%,86.42% and90.18%. There was significantly statistic difference between imiquimod and contrast groups, but no statistic difference between imiquimod and Ara-C. There was significantly statistic difference from imiquimod, contrast groups and the both.Conclusion:It is concluded that TLR7,9 express on acute promyelocytic leukemia and TLR7 agonist imiquimod maybe able to inhibit the growth of HL60 cells, and have effect of promoting. TLR 7 may be the potential application target in the immunotherapy of acute promyelocytic leukemia.