[Abnormally lower expression of cmtm5 gene in bone marrow cells from patients with multiple myeloma]

This study was aimed to detect the expression level of cmtm 5 (CKLF-like MARVEL transmembrane domain containing member 5) gene in the bone marrow cells from patients with multiple myeloma (MM), and to investigate the correlation between the expression level of cmtm5 and various clinical characteristics. Real-time quantitative reverse transcription polymerase chain reaction (RQ-RT-PCR) was used to measure the expression levels of cmtm5 gene in the bone marrow cells collected from MM patients, and the MM cell lines, namely, RPMI8226 and CZ1 cells. The normal donor marrow specimens were used as the reference. The ratio of cmtm5 copy number to abl (Abelson murine leukemia viral oncogene homolog) gene copy number was used for indicating the expression level. The results showed that the expression level of cmtm5 gene was significantly down-regulated in bone marrow cells of 51 untreated or relapsed/refractory MM patient as compared to those of normal donor marrow cells (0.047+/-0.062 for the untreated or relapsed/refractory MM patients versus 0.255+/-0.333 for the normal, p<0.01). According to the International Staging System (ISS), the cmtm5 expression level in marrow cells of patients in ISS III stage was significantly lower than that in patients in ISS I stage (0.034+/-0.034 for the ISS III stage versus 0.103+/-0.109 for ISSI stage, p<0.01). Similarly, lower expression levels of cmtm5 gene were also found in two human MM cell lines (0.014+/-0.009 for RPMI8226 cells and 0.004+/-0.006 for CZ1 cells). After the MM patients were effectively treated, their expression levels of cmtm5 gene significantly increased (0.020+/-0.005 for the untreated patients versus 0.227+/-0.038 for the effectively treated patients, p<0.01). A significant negative correlation was observed between the expression level of cmtm5 gene and the number of bone marrow plasma cells (r=-0.307, p<0.05). However, the correlation was not found between the expression level of cmtm5 gene and the clinical characteristics, such as gender, age, hemoglobin level, or M-protein level, etc. It is concluded that the expression level of cmtm5 gene is abnormally lower in the bone marrow cells from the MM patients, and are associated with ISS stages. Furthermore, the expression level of cmtm5 gene is negatively correlated with the number of bone marrow abnormal plasma cells in MM patients, which suggests that the abnormally lower expression of cmtm5 may be involved in the pathogenesis of the MM patients.