Genomic Characterization Of Newly Established Two Distinct Patient-Driven Multiple Myeloma Cell Lines (SNU_MM1393_BM and SNU_MM1393_SC) From a Single Patient

To establish patient-derived multiple myeloma (MM) cell lines, mononuclear cells obtained from a MM patient’s bone marrow were directly injected via tail vein into a NRG/SCID mouse. Fourteen weeks after injection, tumor developed at subcutis and bone marrow (BM) in the same mouse. We separated and cultured cells from these two sites (subcutis and BM) and established two cell lines originating from a single patient (SNU_MM1393_BM and SNU_MM1393_SC). In cytogenetic analysis, karyotype of newly established two MM cell lines showed tetraploidy which is different from the karyotype of the patient (diploidy) indicating clonal evolution. In FACS analysis, the expression of CD138 and CD45 was detected in both cell lines. Response to IL-6 and soluble IL-6 receptor was different between the two cell lines. Moreover, SNU_MM1393_SC showed higher degree of resistance against proteasome inhibitor (bortezomib) compared to SNU_MM1393_BM. However, two cell lines were both sensitive to histone deacetylase inhibitor (panobinostat).

When whole exome sequencing was performed using the DNA of these two cell lines, a set of somatic mutations involving Wnt signaling and NF-kB pathway were detected in both cell lines. Additional somatic mutations of JAK1, PLCG1, IRS2, and HGS which are known to interact with JAK/STAT pathway were detected in SNU_MM1393_BM. Whereas, additional somatic mutations of EGFR, HSP90AB1, CFDR, and CALML5, which are known to interact with growth factor cell signaling pathway were detected in SNU_MM1393_SC.

These findings highlight the importance of interactions between tumor and tumor microenvironment as the myeloma progresses and will pave a way to more effective selection of targeted agents according to specific tumor characteristics obtained in the process of disease progression.