High throughput quantitative reverse transcription PCR assays revealing over-expression of cancer testis antigen genes in multiple myeloma stem cell-like side population cells

Abstract

Summary Multiple myeloma (MM) stem cells, proposed to be responsible for the tumourigenesis, drug resistance and recurrence of this disease, are enriched in the cancer stem cell-like side population (SP). Cancer testis antigens (CTA) are attractive targets for immunotherapy because they are widely expressed in cancers but only in limited types of normal tissues. We designed a high throughput assay, which allowed simultaneous relative quantifying expression of 90 CTA genes associated with MM. In the three MM cell lines tested, six CTA genes were over-expressed in two and LUZP4 and ODF1 were universally up-regulated in all three cell lines. Subsequent study of primary bone marrow (BM) from eight MM patients and four healthy donors revealed that 19 CTA genes were up-regulated in SP of MM compared with mature plasma cells. In contrast, only two CTA genes showed a moderate increase in SP cells of healthy BM. Furthermore, knockdown using small interfering RNA (siRNA) revealed that LUZP4 expression is required for colony-forming ability and drug resistance in MM cells. Our findings indicate that multiple CTA have unique expression profiles in MM SP, suggesting that CTA may serve as targets for immunotherapy that it specific for MM stem cells and which may lead to the long-term cure of MM.

Dynamic balance of multiple myeloma clonogenic side population cell percentages controlled by environmental conditions

“…The presence of CSCs in a tumor is associated with radioresistance, chemoresistance, local invasion and poor prognosis . Therefore, therapies targeting CSCs seem to be the next logical step in eradicating cancer . Divergent from the currently accepted unidirectional hierarchical model of CSCs, several recent studies instead favor a bidirectional model .…”

“…4,5,32 Therefore, therapies targeting CSCs seem to be the next logical step in eradicating cancer. [33][34][35][36][37][38] Divergent from the currently accepted unidirectional hierarchical model of CSCs, several recent studies instead favor a bidirectional model. 27,30,39 For example, melanoma cells can be dedifferentiated to CSC-like cells by the transfection of the Oct4 gene or transmembrane delivery of the Oct4 protein.…”

227 Luzp4 defines a new mRNA export pathway in cancer cells

“…Here, we have extended that analysis of the Luzp4 expression profile in cancer cells and found it is expressed in a wide variety of cancer types, but particularly high levels of expression are observed in melanoma cells. Recent work identified Luzp4 as commonly up-regulated in multiple myeloma (MM) cell lines and the bone marrow of MM patients, a cell-type absent from our screen of tumours (42). Furthermore this study showed that Luzp4 knockdown prevented colony formation for an MM cell line and sensitized the cell line to chemotherapeutic reagents (arsenic trioxide and bortezomib).…”

Cancer stem cells are the cause of drug resistance in multiple myeloma: fact or fiction?

“…Heightened drug efflux activity is unlikely to be the sole reason for drug resistance in myeloma. In a recent study on the expression of genes encoding cancer testis antigens (CTAs), Wen et al found that these genes were up-regulated in the SP fraction obtained from both human myeloma cell lines (HMCLs) and primary myeloma samples [ 47 ]. Interestingly, one CTA, LUZP7, was essential for drug resistance in myeloma cells.…”