engleski

SPARC gene expression in multiple myeloma patients and its regulation by cytotoxic treatments in myeloma cell lines

Background. SPARC (Osteonectin) is molecule of extracellular matrix with important cell growth, attachment and migration functions. In oncology its role is under intensive investigation since SPARC may support the tumour growth, but may also block its progression acting as tumour suppressor all this depending on the type of neoplasm. We have recently shown that humoral SPARC in MM patients can serve as biomarker. In this study we looked at the SPARC gene expression by MM cells in patients and myeloma cell lines. Aims. We have analyzed the expression of SPARC gene in bone marrow (BM) and peripheral blood (PB) of healthy controls, MM patients and 2 myeloma cell lines: Thiel and NCI H929. Methods. We includeed 35 MM patients and 17 controls into the study. Expression of SPARC and internal housekeeping gene GAPDH was analyzed using quantitative PCR (Taqman gene expression assaysR) in unfractionated mononuclear cells (MNC) from BM and PB and in cell lines grown in standard cultures. Cell lines were in addition treated with bortesomib (BORT), dexamethasone (DEXA), thalidomide (THAL) and cyclosporine (CSA) in different pharmacological concentrations to evaluate its effect on SPARC expression and rate of viability measured by MTT assay. Results. SPARC gene was higher expressed in MM samples compared to controls but only for PB MNCs values reached statistical significance (p=0, 0078, Mann-Whitney). We could not demonstrate correlation between expression values in BM and PB. By the disease stage, SPARC was higher in active disease and lower in Durie-Salmon stage 3. In resistant cell line NCI-H929 (MMSET-IgH+), SPARC was basally low expressed but treatment with THAL and CSA increased its expression, whereas decreased cell viability. In Thiel cell line there was higher basal level of SPARC expression, whereasTHAL and CSA suppressed the expression parallel to reduced viability. BORT treatment in Thiel cells strongly reduced viability with little effect on SPARC expression. Finally, DEXA only slightly suppressed SPARC expression in both cell lines without significant effect on cell viability. Conclusions. Expression of SPARC gene is increased in active myeloma disease with the decline in the expression by disease progression. In vitro results for resistant and non-resistant myeloma cell lines showed different pattern of SPARC gene expression and different response to anti-myeloma drugs. These results warrant further research into the biology of SPARC in MM with future attention to tumour-stroma interaction of marrow microenvironment.

SPARC gene; multiple myeloma; expression

nije evidentirano