[Comparative study of genetic aberrations in human multiple myeloma cell lines and newly diagnosed MM by fluorescence in situ hybridization]

Multiple myeloma (MM) is a neoplasm of a terminally differentiated B-cell. Human myeloma cell lines were shown to be suitable model systems for use in various fields of the biological sciences. This study was aimed to investigate the genetic aberrations in human multiple myeloma cell lines. Interphase fluorescence in situ hybridization (FISH) with probes for the regions containing 13q14 (RB-1), 13q14.3 (D13S19), 14q32 (IGHC/IGHV) , 1q12 (CEP1), 17p13 (TP53) were was used to detect 7 HMCL and 85 cases of newly diagnosed MM. FISH with LSI IGH/CCND1 , LSI IGH/FGFR3 and LSI IGH/MAF probes were used to detect t(11;14) (q13;q32) , t(4;14) (p16;q32) and t(14;16) (q32;q23) in HMCL and MM with 14q32 rearrangement. The results showed that molecular cytogenetic aberrations were found in all 7 HMCL, six (85.7%) HMCL simultaneously had 13q14, 13q14.3 deletion. Chromosome 1q21 abnormality was found in six (33.3%) HMCL with at least 3 copies amplifications. Illegitimate 14q32 rearrangement was found in five (71.4%) HMCL, including one with t(11;14), two with t(4;14) and three with t(14;16). 17p13 deletion was detected in 5 HMCL. Chromosomal changes were observed in 85.9% of the 85 cases of newly diagnosed MM. The del(13), 1q12 amplification, del(17p), 14q32 rearrangement, t(11;14), t(4;14), t(14;16) were present in 44.7%, 52.9%, 20%, 62.4%, 27.1%, 24.7% and 3.5% of the patients respectively. There was no significant difference in the prevalence of genetic abnormalities of del(13q), 14q32 rearrangement, 1q12 amplification, t(11;14), t(4;14) except del(17p) and t(14;16). It is concluded that HMCL representative of the most aggressive phase of plasma cell neoplasms accumulated a large amount of genetic aberrations. Loss of p53 are strikingly common in HMCL suggesting that the impairment of the P53 tumor suppressor pathway is an important contributor to extramedullary tumor expansion.