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Role of Bruton's tyrosine kinase (BTK) in growth and metastasis of INA6 myeloma cells.

Bam R, Venkateshaiah SU, Khan S, Ling W, Randal SS, Li X, Zhang Q, van Rhee F, Barlogie B, Epstein J, Yaccoby S - Blood Cancer J (2014)

Bottom Line: Bruton's tyrosine kinase (BTK) and the chemokine receptor CXCR4 are linked in various hematologic malignancies.BTK knockdown had reduced adhesion to stroma and migration of myeloma cells toward stromal cell-derived factor-1.BTK knockdown myeloma cells had altered the expression of genes associated with adhesion and proliferation and increased mammalian target of rapamycin signaling.

View Article: PubMed Central - PubMed

Affiliation: Myeloma Institute for Research and Therapy, University of Arkansas for Medical Sciences, Little Rock, AR, USA.

ABSTRACT
Bruton's tyrosine kinase (BTK) and the chemokine receptor CXCR4 are linked in various hematologic malignancies. The aim of the study was to understand the role of BTK in myeloma cell growth and metastasis using the stably BTK knockdown luciferase-expressing INA6 myeloma line. BTK knockdown had reduced adhesion to stroma and migration of myeloma cells toward stromal cell-derived factor-1. BTK knockdown had no effect on short-term in vitro growth of myeloma cells, although clonogenicity was inhibited and myeloma cell growth was promoted in coculture with osteoclasts. In severe combined immunodeficient-rab mice with contralaterally implanted pieces of bones, BTK knockdown in myeloma cells promoted their proliferation and growth in the primary bone but suppressed metastasis to the contralateral bone. BTK knockdown myeloma cells had altered the expression of genes associated with adhesion and proliferation and increased mammalian target of rapamycin signaling. In 176 paired clinical samples, BTK and CXCR4 expression was lower in myeloma cells purified from a focal lesion than from a random site. BTK expression in random-site samples was correlated with proportions of myeloma cells expressing cell surface CXCR4. Our findings highlight intratumoral heterogeneity of myeloma cells in the bone marrow microenvironment and suggest that BTK is involved in determining proliferative, quiescent or metastatic phenotypes of myeloma cells.

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BTK knockdown in MM cells reduces their adhesion, impairs their migration and alters their expression of genes associated with adhesion, migration and growth. (a) Bioluminescence analysis of BTK-KD and CONT cells adhering to fibronectin-coated plates alone (left) or with MSCs (right), expressed as percent adherent cells from total cells. (b) Migration of BTK-KD and CONT cells toward SDF-1 (30 nM), expressed as percent changes compared with spontaneous migration without SDF-1. (c, d) Selected overexpressed (high) or underexpressed (low) genes in BTK-KD tumor cells recovered from SCID-rab mice (see Supplmentary Table S1 for the complete list of genes). Bolded gene symbols indicate their expression pattern was originally present in BTK-KD cells cultured in their standard in vitro condition (see Supplmentary Table S2 for the complete list of genes).
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fig5: BTK knockdown in MM cells reduces their adhesion, impairs their migration and alters their expression of genes associated with adhesion, migration and growth. (a) Bioluminescence analysis of BTK-KD and CONT cells adhering to fibronectin-coated plates alone (left) or with MSCs (right), expressed as percent adherent cells from total cells. (b) Migration of BTK-KD and CONT cells toward SDF-1 (30 nM), expressed as percent changes compared with spontaneous migration without SDF-1. (c, d) Selected overexpressed (high) or underexpressed (low) genes in BTK-KD tumor cells recovered from SCID-rab mice (see Supplmentary Table S1 for the complete list of genes). Bolded gene symbols indicate their expression pattern was originally present in BTK-KD cells cultured in their standard in vitro condition (see Supplmentary Table S2 for the complete list of genes).

Mentions: To shed light onto mechanisms mediating reduced metastasis and increased proliferation that result from BTK inhibition, we analyzed cell adhesion, migration and GEP of INA6 MM cells infected with scrambled control shRNA or BTK-KD. The cultured BTK-KD cells adhered to fibronectin 38±6% (P<0.01) less than did control cells, and they adhered to MSCs plus fibronectin 38±3% (P<0.003) less than did control cells (Figure 5a). Because the SDF-1/CXCR4 axis is important for homing of MM cells to bone, we investigated whether BTK inhibition affected migration of MM cells toward SDF-1 gradients. BTK knockdown did not reduce cell surface levels of CXCR4 (data not shown) but significantly reduced the ability of INA6 cells to migrate toward SDF-1 (Figure 5b). These data suggest that BTK knockdown reduced migration as well as adhesion of INA6 MM cells.


Role of Bruton's tyrosine kinase (BTK) in growth and metastasis of INA6 myeloma cells.

Bam R, Venkateshaiah SU, Khan S, Ling W, Randal SS, Li X, Zhang Q, van Rhee F, Barlogie B, Epstein J, Yaccoby S - Blood Cancer J (2014)

BTK knockdown in MM cells reduces their adhesion, impairs their migration and alters their expression of genes associated with adhesion, migration and growth. (a) Bioluminescence analysis of BTK-KD and CONT cells adhering to fibronectin-coated plates alone (left) or with MSCs (right), expressed as percent adherent cells from total cells. (b) Migration of BTK-KD and CONT cells toward SDF-1 (30 nM), expressed as percent changes compared with spontaneous migration without SDF-1. (c, d) Selected overexpressed (high) or underexpressed (low) genes in BTK-KD tumor cells recovered from SCID-rab mice (see Supplmentary Table S1 for the complete list of genes). Bolded gene symbols indicate their expression pattern was originally present in BTK-KD cells cultured in their standard in vitro condition (see Supplmentary Table S2 for the complete list of genes).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4219470&req=5

fig5: BTK knockdown in MM cells reduces their adhesion, impairs their migration and alters their expression of genes associated with adhesion, migration and growth. (a) Bioluminescence analysis of BTK-KD and CONT cells adhering to fibronectin-coated plates alone (left) or with MSCs (right), expressed as percent adherent cells from total cells. (b) Migration of BTK-KD and CONT cells toward SDF-1 (30 nM), expressed as percent changes compared with spontaneous migration without SDF-1. (c, d) Selected overexpressed (high) or underexpressed (low) genes in BTK-KD tumor cells recovered from SCID-rab mice (see Supplmentary Table S1 for the complete list of genes). Bolded gene symbols indicate their expression pattern was originally present in BTK-KD cells cultured in their standard in vitro condition (see Supplmentary Table S2 for the complete list of genes).
Mentions: To shed light onto mechanisms mediating reduced metastasis and increased proliferation that result from BTK inhibition, we analyzed cell adhesion, migration and GEP of INA6 MM cells infected with scrambled control shRNA or BTK-KD. The cultured BTK-KD cells adhered to fibronectin 38±6% (P<0.01) less than did control cells, and they adhered to MSCs plus fibronectin 38±3% (P<0.003) less than did control cells (Figure 5a). Because the SDF-1/CXCR4 axis is important for homing of MM cells to bone, we investigated whether BTK inhibition affected migration of MM cells toward SDF-1 gradients. BTK knockdown did not reduce cell surface levels of CXCR4 (data not shown) but significantly reduced the ability of INA6 cells to migrate toward SDF-1 (Figure 5b). These data suggest that BTK knockdown reduced migration as well as adhesion of INA6 MM cells.

Bottom Line: Bruton's tyrosine kinase (BTK) and the chemokine receptor CXCR4 are linked in various hematologic malignancies.BTK knockdown had reduced adhesion to stroma and migration of myeloma cells toward stromal cell-derived factor-1.BTK knockdown myeloma cells had altered the expression of genes associated with adhesion and proliferation and increased mammalian target of rapamycin signaling.

View Article: PubMed Central - PubMed

Affiliation: Myeloma Institute for Research and Therapy, University of Arkansas for Medical Sciences, Little Rock, AR, USA.

ABSTRACT
Bruton's tyrosine kinase (BTK) and the chemokine receptor CXCR4 are linked in various hematologic malignancies. The aim of the study was to understand the role of BTK in myeloma cell growth and metastasis using the stably BTK knockdown luciferase-expressing INA6 myeloma line. BTK knockdown had reduced adhesion to stroma and migration of myeloma cells toward stromal cell-derived factor-1. BTK knockdown had no effect on short-term in vitro growth of myeloma cells, although clonogenicity was inhibited and myeloma cell growth was promoted in coculture with osteoclasts. In severe combined immunodeficient-rab mice with contralaterally implanted pieces of bones, BTK knockdown in myeloma cells promoted their proliferation and growth in the primary bone but suppressed metastasis to the contralateral bone. BTK knockdown myeloma cells had altered the expression of genes associated with adhesion and proliferation and increased mammalian target of rapamycin signaling. In 176 paired clinical samples, BTK and CXCR4 expression was lower in myeloma cells purified from a focal lesion than from a random site. BTK expression in random-site samples was correlated with proportions of myeloma cells expressing cell surface CXCR4. Our findings highlight intratumoral heterogeneity of myeloma cells in the bone marrow microenvironment and suggest that BTK is involved in determining proliferative, quiescent or metastatic phenotypes of myeloma cells.

Show MeSH
Related in: MedlinePlus