Establishment and Characterization of a Myeloma Cell Line- Aku-MY01

Introduction:

Multiple myeloma (MM) is characterized by expansion of neoplastic plasma cells (PCs). Disease presentation is heterogenous with hypercalcemia, renal failure, osteolytic lesions or a combination thereof. The overall survival of patients and their response to treatment has improved considerably however, MM stays incurable. Patients develop treatment resistance and progress to relapse. Disease progression to treatment resistance and relapse are attributed to complex signaling molecules. In vitro experiments on cell lines are pivotal to determine the functional characterization of these molecules leading to identification of potential therapeutic targets.

Cell lines have served as instruments for research in varied disciplines including cancer. Currently, majority of the cell lines in cancer research are from European origin and to a lesser extent from Africans, Asians and Hispanic populations. This lacuna of inadequate racial and genetic representation leads to major consequences such as delays in the benefits of precision medicine, drug efficacy and partial understanding of molecular aspects of the disease. The study was undertaken to establish and characterize a cell line from a patient diagnosed with MM.

Methods

AKU-MY01 was established from a 38-year male patient diagnosed with ISS stage III, kappa light chain myeloma in 2013. Plasma cells were isolated from the BM aspirate using sterile conditions and cultured in RPMI-1640 supplemented with 10% FBS. Conditioned media from urinary bladder carcinoma cell line 5637 was used to provide growth factors. Isolated suspension cells were observed in culture which were subcultured by splitting in a 1:3 ratios. Detailed characterization of AKU-MY01 was undertaken using gene expression analysis, population doubling time (PDT), determination of clonality, fluorescent in situ hybridization, immunocytochemistry (ICC), karyotyping, transwell assay and short tandem repeat (STR) analysis.

Results:

AKU-MY01 showed expression of ABCG2^dim, Oct4, CD38, CD138, CD19, CD20, CD45, CD56 ^dim, XBP1, MUC1, EBNA1, and monoclonal Lambda light chain. AKU-MY01 exhibited a human diploid karyotype with 46XY and IGH deletions/translocation in 20% of the cells. It has a PDT of 48-53 hrs. and high invasive potential (15.6%) compared to other MM cell lines. Expression of EBNA at mRNA level was further confirmed through fluorescent ICC. The results from Immunofluorescent ICC showed clusters of tumor cells with concordant expression of membranous CD138 and cytosolic and nuclear expression of LMP1. Further, the expression of LMP1 in CD138 positive tumor cells was confirmed in Patient's trephine from whome AKU-MY01 was derived.

Conclusion:

To the best of our knowledge, AKU-MY01 is the first MM cell line characterized for LMP1 expression in CD138 expressing myeloma cells. Salient features of AKU-MY01 which make it a unique addition to the existing repertoire of MM cell lines are a) Asian origin, b) diploid karyotype and c) expression of EBV protein and mRNA. Further studies using this cell line model may contribute to understand the biology of EBV positive MM cases.