Detection And Phylogenetic Analysis Of Retroviral Pol Sequence In Plasma From Patients With Chronic Myeloid Leukemia

BackgroundLeukemia is a common human cancer. However, except Adult T-cell Leukemia/Lymphoma (ATLL) and Human T-cell Leukemia Virus Type-1 (HTLV-1), the causes of other types of leukemia including the chronic myeloid leukemia (CML) have not been defined yet. Precious studies suggested that retroviruses may involve in the iniation and development of chronic myeloid leukemia.Objective and MethodsTo explore the association between the retrovirus and the chronic myeloid leukemia, CML patients (n=39) and the control group(healthy people (n=46) and the acute leukemia patients (n=15))were studied. We extract the RNA from the plasma of both the CML group and the control group, and then the extraced RNA is treated with the DNase to remove DNA; employ a semi-nested PCR to amplify the retroviral pol sequence; the PCR-positive amplification products have been cloned and sequenced. According to the the PCR positive data, we analyse whether there is a statistical difference in the expression of retroviral pol gene between the CML patients and the control group; Compare the identities between the retroviral pol sequence abtained in this study and the corresponding segment of some associated retroviruses and performe phylogenetic analysis among the retroviral pol sequence and other retroviruses.ResultsStatistical analysis of the RT-PCR results demonstrated that: 1) when compared with the healthy group, the positive rate of the retroviral pol gene expression is significantly higher(P<0.05); 2) when compared with the control group of AL patients, it is also significantly higher(P<0.05).From this study, we abtained one 126nt long sequece and it is temporarily named ST-CMLRV. Sequence analysis showed that the ST-CMLRV is mostly associated with the Multiple sclerosis associated retrovirus polyprotein (pol) mRNA (the identity of the nucleotide and the amino acid is 92% and 85% respectively). Phylogenetic analysis dispalyed that the ST-CMLRV is derived from the family of the Human Endogenous Retrovirus-W (HERV-W) and it is different from the Human Immunodeficiency Virus (HIV) and HTLV. ConclusionsThe results in this study preliminarily demonstrated that the CML may be associated with the expression of HERV. But further studies are required to determine the etiology between retroviruses and CML, and to identify a role of retroviruses especially the HERV in the development of CML.