Sentences with phrase «abl kinases»

In breast cancer cells, the ABL kinases activated the transcriptional coactivator TAZ and the transcription factor STAT5, which triggered the transcription of genes encoding factors that activate osteoclasts (cells that break down bone) and those that enhance the survival of breast cancer cells in the bone microenvironment.

We report that ABL kinases promoted metastasis of breast cancer cells to bone by regulating the crosstalk between tumor cells and the bone microenvironment.

Together, our findings suggest that ABL kinases activate the TAZ and STAT5 pathways and that coactivation of their downstream targets promote the bone metastasis of breast cancer cells in mouse models.

To directly examine whether ABL kinases regulate tumor - induced osteoclast activation, we used an in vitro osteoclastogenesis assay (Fig. 5A).

These data suggest that ABL kinases promote breast cancer metastasis to bone in part by increasing tumor cell survival within the bone microenvironment.

Depletion of ABL kinases in breast cancer cells decreased IL - 6 concentrations and was accompanied by increased OPG expression in osteoblasts.

Together, these data revealed a functional link between the ABL kinases and TAZ signaling leading to increased AXL abundance in breast cancer cells, and identified a potentially druggable pathway for the treatment of breast cancer bone metastasis.

However, we can not rule out the possibility that ABL kinases might regulate YAP1 - mediated expression of other target genes in breast cancer cells.

Mechanistically, we found that STAT5 was required for the production of the secreted factors MMP1, IL - 6, and TNC, downstream of ABL kinases.

Depletion of ABL kinases impairs tumor - induced osteoclast activation in part by decreasing IL - 6 secretion.

Depletion of ABL kinases in breast cancer cells also decreased the abundance of MMP1, a protease that cleaves fibrillar collagens and promotes the proteolytic release of bound growth factors (32).

Whereas conditioned medium from ABL1 / ABL2 - depleted breast cancer cells did not affect RANKL abundance in osteoblasts compared with the cells treated with control conditioned medium (Fig. 5E), we found that conditioned medium from breast cancer cells lacking ABL kinases increased OPG abundance in the osteoblast cell line (Fig. 5F).

To identify key molecular mediators of the ABL kinases implicated in the regulation of the ABL1 / ABL2 - dependent pathways, we analyzed the expression of individual genes for transcripts altered by loss of the ABL kinases.

To examine the functional role of ABL kinases in these cells, we depleted endogenous ABL kinases with previously characterized short hairpin RNAs (shRNAs) specific against ABL1 and ABL2 (20).

Conversely, overexpression of ABL kinases, predominantly ABL1, in both 1833 and parental MDA - MB - 231 breast cancer cells increased STAT5 phosphorylation (fig.

Further, inactivation of the ABL kinases resulted in decreased expression of the genes in the Hippo, Janus kinase (JAK) / STAT, and cytokine / cytokine receptor pathway signatures (Fig. 6B).

We found that inactivation of the ABL kinases in breast cancer cells also decreased STAT5A mRNA and downstream expression of STAT5 target genes, including TNC (Fig. 6D).

These findings suggest that ABL kinases promote tumor - induced osteoclast activation in part by increasing OPG abundance in osteoblasts.

Depletion of ABL kinases does not affect YAP1 protein abundance, localization, or tyrosine phosphorylation in breast cancer cells.

However, depletion of ABL kinases decreased the phosphorylation of STAT5 (Fig. 7D and fig.

We found that allosteric inhibition of the ABL kinases effectively impaired breast cancer bone metastasis and blocked tumor - induced osteolysis in mouse models.

These findings suggest that ABL kinases regulate osteoclast maturation indirectly, possibly by modulating osteoblast function.

Expression of a constitutively active STAT5A mutant (STAT5A *) reversed the reduction in MMP1, IL - 6, and TNC abundance induced by depletion of both ABL kinases in breast cancer cells (Fig. 7, E and F, and fig.

Thus, we evaluated whether addition of IL - 6 could in part rescue defective osteoclastogenesis induced by conditioned medium from breast cancer cells depleted of the ABL kinases.

Our data raise the possibility that inhibition of ABL kinases can increase apoptosis of breast cancer cells and block osteoclast activation, which is required for osteolytic metastasis.

Double knockdown of ABL1 and ABL2 was required to decrease the phosphorylation of CrkL by more than 90 %, which indicates inactivation of the endogenous ABL kinases (Fig. 2K).

Here, we uncovered a role for the ABL kinases in promoting breast cancer bone metastasis through the regulation of distinct pathways required for tumor colonization and survival in the bone microenvironment.

Moreover, we found that treatment with a selective allosteric inhibitor of the ABL kinases or simultaneous depletion of both ABL kinases in breast cancer cells impaired breast cancer bone metastases and decreased osteoclast activation in vitro and osteolysis in vivo.

These findings reveal a function for ABL kinases in the regulation of breast cancer bone metastasis and tumor - induced osteolysis in vivo.

The allosteric inhibitors specific for ABL kinases (which are currently in clinical trials) provide a potentially useful tool for selectively targeting ABL kinases in metastatic breast cancer types with an increase in the ABL pathway signature (58).

To directly examine whether ABL kinases play a role in regulating the colonization and survival of breast cancer cells in the bone microenvironment, we injected control or ABL1 / ABL2 knockdown breast cancer cells directly into the tibia of immunodeficient mice.

Further, we identified a role for ABL kinases in promoting the expression of multiple pro — bone metastasis genes such as AXL (which encodes a receptor tyrosine kinase), IL6 (which encodes interleukin - 6), MMP1 (which encodes matrix metalloproteinase 1), and TNC (which encodes tenascin - C) through TAZ - and signal transducer and activator of transcription 5 (STAT5)-- mediated signaling.

Regardless, our data support a role for ABL kinases in the regulation of TAZ protein abundance and activity in breast cancer cells.

We found that ~ 90 % knockdown of ABL1 alone resulted in enhanced ABL2 expression and did not produce a significant decrease in the phosphorylation of CrkL, a reporter for the activation state of the ABL kinases (Fig. 2K), and did not inhibit metastasis (Fig. 2, L and M).

Inactivation of ABL kinases inhibited the expression of the TAZ target gene AXL, which shows increased expression in several human cancers and correlates with poor prognosis, increased invasiveness and metastasis, and enhanced drug resistance (53, 54).

We showed that inactivation of the ABL kinases in breast cancer cells resulted in decreased expression of genes in the JAK / STAT and cytokine / cytokine receptor pathway signatures, which may be due to decreased STAT5A mRNA expression and reduced STAT5 phosphorylation in ABL1 / ABL2 - depleted breast cancer cells.

TRAIL - enhanced apoptosis as measured by cleavage of caspase - 3 (Fig. 4I), and knockdown of ABL kinases increased the sensitivity of 1833 breast cancer cells to the proapoptotic effects of TRAIL (Fig. 4, G to I).

Abl kinases are required for vascular function, Tie2 expression, and angiopoietin - 1 — mediated survival

To evaluate whether ABL kinases might regulate the secretion of osteoblast - derived RANKL or OPG leading to osteoclast differentiation, we analyzed RANKL and OPG mRNA abundance in the murine osteoblast cell line 7F2 in response to conditioned medium from control and ABL1 / ABL2 knockdown breast cancer cells.

ABL kinases regulate the expression of genes in the JAK / STAT and Hippo pathway signatures in metastatic breast cancer cells.

However, these reciprocal decreases were much lower than those induced by knockdown of the ABL kinases (Fig. 7).

Depletion of ABL kinases does not inhibit metastasis of 4175 breast cancer cells, which show tropism to the lung.

To evaluate whether loss of ABL kinases affected TAZ activity, we performed chromatin immunoprecipitation (ChIP) analysis using primers for TAZ targets identified by ChIP sequencing analysis (42).

We found that depletion of the ABL kinases decreased TAZ binding to some of its target genes (fig.

To evaluate whether the TAZ and STAT5 pathways promote breast cancer bone metastasis downstream of the ABL kinases, we expressed the constitutively active mutants TAZ S89A and STAT5 * in ABL1 / ABL2 knockdown cells.

In addition to inhibiting STAT5 signaling, we found that depletion of ABL kinases decreased the expression of the Hippo pathway mediator TAZ and downstream target genes in triple - negative and HER2 + breast cancer cells.

Here, we uncovered a critical role for ABL kinases in the regulation of breast cancer metastasis to bone.

We found that depletion of ABL kinases in breast cancer cells decreased STAT5A mRNA expression (Fig. 6D) without decreasing total STAT5 protein abundance as measured by Western blotting with antibodies that detect both STAT5A and STAT5B (Fig. 7D and fig.

ABL kinases regulate cancer cell invasion (21), but it is unclear whether they play a role in the regulation of subsequent steps of the metastatic cascade.

However, whether ABL kinases have a role in the regulation of cellular processes critical for metastasis, other than invasion, has not yet been evaluated.