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CXCL12-induced VLA-4 activation is impaired in trisomy 12 chronic lymphocytic leukemia cells: a role for CCL21.

Ganghammer S, Hutterer E, Hinterseer E, Brachtl G, Asslaber D, Krenn PW, Girbl T, Berghammer P, Geisberger R, Egle A, Zucchetto A, Kruschinski A, Gattei V, Chigaev A, Greil R, Hartmann TN - Oncotarget (2015)

Bottom Line: Here, we demonstrate that high CD49d expression in tri12 CLL is accompanied by decreased CXCR4 expression.Concordantly, in real-time kinetic analyses we found CCL21 but not CXCL12 being capable to induce inside-out VLA-4 conformational changes in this CLL subgroup.Our results provide novel insights into the peculiar clinico-biological behaviour of tri12 CLL and emphasize its specific chemokine and integrin utilization during pathophysiologically and therapeutically relevant interactions with the microenvironment.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Immunological and Molecular Cancer Research, 3rd Medical Department with Hematology, Medical Oncology, Hemostaseology, Infectious Diseases and Rheumatology, Oncologic Center, Paracelsus Medical University Salzburg, Austria.

ABSTRACT
Homing to distinct lymphoid organs enables chronic lymphocytic leukemia (CLL) cells to receive pro-survival and proliferative signals. Cytogenetic aberrations can significantly affect CLL cell compartmentalization. Trisomy 12 (tri12) defines a CLL subgroup with specific clinical features and increased levels of the negative prognostic marker CD49d, the α4-subunit of the integrin VLA-4, which is a key regulator of CLL cell homing to bone marrow (BM). Chemokine-induced inside-out VLA-4 activation, particularly via the CXCL12-CXCR4 axis, increases the arrest of various cell types on VCAM-1 presenting endothelium. Here, we demonstrate that high CD49d expression in tri12 CLL is accompanied by decreased CXCR4 expression. Dissecting functional consequences of these alterations, we observed that tri12 CLL cell homing to murine BM is not affected by CXCR4-CXCL12 blockage using AMD3100 or olaptesed pegol/NOX-A12. In line, CCL21-CCR7 rather than CXCL12-CXCR4 interactions triggered VLA-4-mediated arrests of tri12 CLL cells to VCAM-1 under blood flow conditions. Concordantly, in real-time kinetic analyses we found CCL21 but not CXCL12 being capable to induce inside-out VLA-4 conformational changes in this CLL subgroup. Our results provide novel insights into the peculiar clinico-biological behaviour of tri12 CLL and emphasize its specific chemokine and integrin utilization during pathophysiologically and therapeutically relevant interactions with the microenvironment.

No MeSH data available.


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CXCR4 and CD49d expression of tri12 and no tri12 CLL cellsFlow-cytometric determination of (A) CXCR4 MFIR values and (B) CD49d expression (% positive cells) in CLL cases split into four groups according to the presence of tri12 and CD49d (tri12−/CD49d−: n = 142, tri12−/CD49d+: n = 57, tri12+/CD49d−: n = 3, tri12+/CD49d+: n = 24). Scatter plots, the middle lines indicate the median. CD49d− subgroups are defined by expression on <30%, CD49d+ subgroups by expression on ≥30% of the CLL cells. (C) Correlation between the percentage of CD49d+ cells and the corresponding CD49d MFIR values. (D) Correlation (Spearman's test) between the MFIR values of CD49d and CXCR4 (n = 226).
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Figure 1: CXCR4 and CD49d expression of tri12 and no tri12 CLL cellsFlow-cytometric determination of (A) CXCR4 MFIR values and (B) CD49d expression (% positive cells) in CLL cases split into four groups according to the presence of tri12 and CD49d (tri12−/CD49d−: n = 142, tri12−/CD49d+: n = 57, tri12+/CD49d−: n = 3, tri12+/CD49d+: n = 24). Scatter plots, the middle lines indicate the median. CD49d− subgroups are defined by expression on <30%, CD49d+ subgroups by expression on ≥30% of the CLL cells. (C) Correlation between the percentage of CD49d+ cells and the corresponding CD49d MFIR values. (D) Correlation (Spearman's test) between the MFIR values of CD49d and CXCR4 (n = 226).

Mentions: To investigate the contribution of CXCL12-CXCR4 signals to VLA-4 dependent BM homing of tri12 versus no tri12 CLL cells, we first compared CXCR4 expression in a cohort of 226 CLL samples expressing or not expressing the VLA-4 rate limiting subunit CD49d, according to the well established prognostic cutoff of 30% positive cells [16, 22], and bearing or not bearing tri12 (Supplemental Table 1). CXCR4 expression, measured as mean fluorescence intensity ratios (MFIR), was significantly lower in CD49d+ subgroups than in CD49d− subgroups, the lowest levels being found in CD49d+ tri12 samples (Figure 1A). Notably, this reduction did not result in decreased fractions of CXCR4+ cells but was a global reduction of CXCR4 expression intensity on all CLL cells within the sample (Supplemental Figure 1). CD49d expression (% positive cells) was highest in CD49d+ tri12 samples, confirming our recent data (Figure 1B) [14]. Consistently, the percentage of CD49d+ cells directly correlated with the CD49d fluorescence intensity (Figure 1C). We also observed a moderate inverse correlation of CXCR4 and CD49d expression intensities on CLL cells (Figure 1D).


CXCL12-induced VLA-4 activation is impaired in trisomy 12 chronic lymphocytic leukemia cells: a role for CCL21.

Ganghammer S, Hutterer E, Hinterseer E, Brachtl G, Asslaber D, Krenn PW, Girbl T, Berghammer P, Geisberger R, Egle A, Zucchetto A, Kruschinski A, Gattei V, Chigaev A, Greil R, Hartmann TN - Oncotarget (2015)

CXCR4 and CD49d expression of tri12 and no tri12 CLL cellsFlow-cytometric determination of (A) CXCR4 MFIR values and (B) CD49d expression (% positive cells) in CLL cases split into four groups according to the presence of tri12 and CD49d (tri12−/CD49d−: n = 142, tri12−/CD49d+: n = 57, tri12+/CD49d−: n = 3, tri12+/CD49d+: n = 24). Scatter plots, the middle lines indicate the median. CD49d− subgroups are defined by expression on <30%, CD49d+ subgroups by expression on ≥30% of the CLL cells. (C) Correlation between the percentage of CD49d+ cells and the corresponding CD49d MFIR values. (D) Correlation (Spearman's test) between the MFIR values of CD49d and CXCR4 (n = 226).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4494922&req=5

Figure 1: CXCR4 and CD49d expression of tri12 and no tri12 CLL cellsFlow-cytometric determination of (A) CXCR4 MFIR values and (B) CD49d expression (% positive cells) in CLL cases split into four groups according to the presence of tri12 and CD49d (tri12−/CD49d−: n = 142, tri12−/CD49d+: n = 57, tri12+/CD49d−: n = 3, tri12+/CD49d+: n = 24). Scatter plots, the middle lines indicate the median. CD49d− subgroups are defined by expression on <30%, CD49d+ subgroups by expression on ≥30% of the CLL cells. (C) Correlation between the percentage of CD49d+ cells and the corresponding CD49d MFIR values. (D) Correlation (Spearman's test) between the MFIR values of CD49d and CXCR4 (n = 226).
Mentions: To investigate the contribution of CXCL12-CXCR4 signals to VLA-4 dependent BM homing of tri12 versus no tri12 CLL cells, we first compared CXCR4 expression in a cohort of 226 CLL samples expressing or not expressing the VLA-4 rate limiting subunit CD49d, according to the well established prognostic cutoff of 30% positive cells [16, 22], and bearing or not bearing tri12 (Supplemental Table 1). CXCR4 expression, measured as mean fluorescence intensity ratios (MFIR), was significantly lower in CD49d+ subgroups than in CD49d− subgroups, the lowest levels being found in CD49d+ tri12 samples (Figure 1A). Notably, this reduction did not result in decreased fractions of CXCR4+ cells but was a global reduction of CXCR4 expression intensity on all CLL cells within the sample (Supplemental Figure 1). CD49d expression (% positive cells) was highest in CD49d+ tri12 samples, confirming our recent data (Figure 1B) [14]. Consistently, the percentage of CD49d+ cells directly correlated with the CD49d fluorescence intensity (Figure 1C). We also observed a moderate inverse correlation of CXCR4 and CD49d expression intensities on CLL cells (Figure 1D).

Bottom Line: Here, we demonstrate that high CD49d expression in tri12 CLL is accompanied by decreased CXCR4 expression.Concordantly, in real-time kinetic analyses we found CCL21 but not CXCL12 being capable to induce inside-out VLA-4 conformational changes in this CLL subgroup.Our results provide novel insights into the peculiar clinico-biological behaviour of tri12 CLL and emphasize its specific chemokine and integrin utilization during pathophysiologically and therapeutically relevant interactions with the microenvironment.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Immunological and Molecular Cancer Research, 3rd Medical Department with Hematology, Medical Oncology, Hemostaseology, Infectious Diseases and Rheumatology, Oncologic Center, Paracelsus Medical University Salzburg, Austria.

ABSTRACT
Homing to distinct lymphoid organs enables chronic lymphocytic leukemia (CLL) cells to receive pro-survival and proliferative signals. Cytogenetic aberrations can significantly affect CLL cell compartmentalization. Trisomy 12 (tri12) defines a CLL subgroup with specific clinical features and increased levels of the negative prognostic marker CD49d, the α4-subunit of the integrin VLA-4, which is a key regulator of CLL cell homing to bone marrow (BM). Chemokine-induced inside-out VLA-4 activation, particularly via the CXCL12-CXCR4 axis, increases the arrest of various cell types on VCAM-1 presenting endothelium. Here, we demonstrate that high CD49d expression in tri12 CLL is accompanied by decreased CXCR4 expression. Dissecting functional consequences of these alterations, we observed that tri12 CLL cell homing to murine BM is not affected by CXCR4-CXCL12 blockage using AMD3100 or olaptesed pegol/NOX-A12. In line, CCL21-CCR7 rather than CXCL12-CXCR4 interactions triggered VLA-4-mediated arrests of tri12 CLL cells to VCAM-1 under blood flow conditions. Concordantly, in real-time kinetic analyses we found CCL21 but not CXCL12 being capable to induce inside-out VLA-4 conformational changes in this CLL subgroup. Our results provide novel insights into the peculiar clinico-biological behaviour of tri12 CLL and emphasize its specific chemokine and integrin utilization during pathophysiologically and therapeutically relevant interactions with the microenvironment.

No MeSH data available.


Related in: MedlinePlus