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Increased Wnt5a in squamous cell lung carcinoma inhibits endothelial cell motility

View Article: PubMed Central - PubMed

ABSTRACT

Background: Angiogenesis is important both in normal tissue function and disease and represents a key target in lung cancer (LC) therapy. Unfortunately, the two main subtypes of non-small-cell lung cancers (NSCLC) namely, adenocarcinoma (AC) and squamous cell carcinoma (SCC) respond differently to anti-angiogenic e.g. anti-vascular endothelial growth factor (VEGF)-A treatment with life-threatening side effects, often pulmonary hemorrhage in SCC. The mechanisms behind such adverse reactions are still largely unknown, although peroxisome proliferator activator receptor (PPAR) gamma as well as Wnt-s have been named as molecular regulators of the process. As the Wnt microenvironments in NSCLC subtypes are drastically different, we hypothesized that the particularly high levels of non-canonical Wnt5a in SCC might be responsible for alterations in blood vessel growth and result in serious adverse reactions.

Methods: PPARgamma, VEGF-A, Wnt5a, miR-27b and miR-200b levels were determined in resected adenocarcinoma and squamous cell carcinoma samples by qRT-PCR and TaqMan microRNA assay. The role of PPARgamma in VEGF-A expression, and the role of Wnts in overall regulation was investigated using PPARgamma knock-out mice, cancer cell lines and fully human, in vitro 3 dimensional (3D), distal lung tissue aggregates. PPARgamma mRNA and protein levels were tested by qRT-PCR and immunohistochemistry, respectively. PPARgamma activity was measured by a PPRE reporter system. The tissue engineered lung tissues expressing basal level and lentivirally delivered VEGF-A were treated with recombinant Wnts, chemical Wnt pathway modifiers, and were subjected to PPARgamma agonist and antagonist treatment.

Results: PPARgamma down-regulation and VEGF-A up-regulation are characteristic to both AC and SCC. Increased VEGF-A levels are under direct control of PPARgamma. PPARgamma levels and activity, however, are under Wnt control. Imbalance of both canonical (in AC) and non-canonical (in SCC) Wnts leads to PPARgamma down-regulation. While canonical Wnts down-regulate PPARgamma directly, non-canonical Wnt5a increases miR27b that is known regulator of PPARgamma.

Conclusion: During carcinogenesis the Wnt microenvironment alters, which can downregulate PPARgamma leading to increased VEGF-A expression. Differences in the Wnt microenvironment in AC and SCC of NSCLC lead to PPARgamma decrease via mechanisms that differentially alter endothelial cell motility and branching which in turn can influence therapeutic response.

Electronic supplementary material: The online version of this article (doi:10.1186/s12885-016-2943-4) contains supplementary material, which is available to authorized users.

No MeSH data available.


The effect of Wnt5a on VEGF-A induced endothelial cell activation and motility. a, CD105 mRNA expression is significantly higher in primary AC compared to SCC samples. Error bars, SEM. One-way ANOVA, post hoc Bonferroni; n = 11 and n = 12 per groups. b, Flow cytometric analysis of CD105 protein expression in CD31 positive endothelial cells in primary AC and SCC samples. n = 6 per groups. c, Flow cytometric analysis of CD105 levels in normal and high VEGF-A microenvironment in 3D lung aggregate tissues has also shown an increase of activation marker CD105 in VEGF-Ahigh tissues. The double positive (CD105/CD31) cell population was considered as activated endothelial cells. Independent samples t-test, n = 6. 1 μg/ml rhWnt5a treatment had no effect on the VEGF-A induced endothelial cell activation measured by the double positive (CD105/CD31) cell population identified by flow cytometric analysis. Independent samples t-test, n = 6. d, Localization of endothelial cells was identified by immunoflurescent staining of CD31 and analyzed by confocal microscopy in 3D lung tissue aggregates. In VEGF-Anormal microenvironment endothelial cells remained diffuse in the tissue. Under VEGF-A excess endothelial cell migrated towards the source (VEGF-Ahigh fibroblasts) of the signal in the center of the aggregate tissue. 1 μg/ml rhWnt5a treatment of VEGF-Ahigh tissue aggregates inhibited endothelial cell accumulation in the center of the aggregate. Bar chart represents the quantification of endothelial cell distribution. Relative area of CD31+ endothelial cells are compared to total field. Percentages were calculated as relative area of endothelial cells/area of total field *100. Error bars; SEM. Independent samples t-test n = 3. Representative images of three independent experiments are shown. Scale bars, 50 μm. e, HMVEC-L transwell migration assay. Endothelial cells migrate significantly faster towards VEGF-Ahigh fibroblast, while 1 μg/ml rhWnt5a can reverse the effect of elevated VEGF-A level. Scale bar 100 μm. One-way ANOVA, n = 3. P < 0.05 was considered as significant, * p < 0.05, ** p < 0.01, *** p < 0.001
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Fig4: The effect of Wnt5a on VEGF-A induced endothelial cell activation and motility. a, CD105 mRNA expression is significantly higher in primary AC compared to SCC samples. Error bars, SEM. One-way ANOVA, post hoc Bonferroni; n = 11 and n = 12 per groups. b, Flow cytometric analysis of CD105 protein expression in CD31 positive endothelial cells in primary AC and SCC samples. n = 6 per groups. c, Flow cytometric analysis of CD105 levels in normal and high VEGF-A microenvironment in 3D lung aggregate tissues has also shown an increase of activation marker CD105 in VEGF-Ahigh tissues. The double positive (CD105/CD31) cell population was considered as activated endothelial cells. Independent samples t-test, n = 6. 1 μg/ml rhWnt5a treatment had no effect on the VEGF-A induced endothelial cell activation measured by the double positive (CD105/CD31) cell population identified by flow cytometric analysis. Independent samples t-test, n = 6. d, Localization of endothelial cells was identified by immunoflurescent staining of CD31 and analyzed by confocal microscopy in 3D lung tissue aggregates. In VEGF-Anormal microenvironment endothelial cells remained diffuse in the tissue. Under VEGF-A excess endothelial cell migrated towards the source (VEGF-Ahigh fibroblasts) of the signal in the center of the aggregate tissue. 1 μg/ml rhWnt5a treatment of VEGF-Ahigh tissue aggregates inhibited endothelial cell accumulation in the center of the aggregate. Bar chart represents the quantification of endothelial cell distribution. Relative area of CD31+ endothelial cells are compared to total field. Percentages were calculated as relative area of endothelial cells/area of total field *100. Error bars; SEM. Independent samples t-test n = 3. Representative images of three independent experiments are shown. Scale bars, 50 μm. e, HMVEC-L transwell migration assay. Endothelial cells migrate significantly faster towards VEGF-Ahigh fibroblast, while 1 μg/ml rhWnt5a can reverse the effect of elevated VEGF-A level. Scale bar 100 μm. One-way ANOVA, n = 3. P < 0.05 was considered as significant, * p < 0.05, ** p < 0.01, *** p < 0.001

Mentions: As VEGF-A has previously been determined to stimulate endothelial cell proliferation and migration [53], expression of endoglin (Eng or CD105) a transmembrane auxillary receptor for transforming growth factor-beta (TGF-beta) that is predominantly expressed on proliferating endothelial cells was also tested [54]. Analysis of primary SCC and AC tissue samples revealed that the endothelial cell proliferation marker Eng (CD105) was significantly lower in SCC compared to AC (Fig. 4a and b). Although VEGF-A was significantly higher than normal in both cancer subtypes, VEGF-A levels in SCC were lower than in AC (Fig. 1b). To be able to study the molecular effects of high VEGF-A levels on endothelial cells, in vitro studies were performed using a three dimensional (3D) human lung aggregate model tissue consisting of primary human small airway epithelial cells (SAEC), microvascular lung endothelial cells (HMVEC-L), and human fibroblasts (NHLF and F11) (Additional file 2: Figure S1). The 3D aggregate culture conditions provided close to natural, yet defined, cellular environment for molecular studies. qRT-PCR analysis of the lung model tissue aggregates revealed highly similar expression levels of angiogenic stimulators including VEGF-A, IL-1beta and HIF-1alpha to primary human lungs (Additional file 3: Figure S2) indicating that the model is suitable to study pro- and/or anti-angiogenic mechanisms. To recreate the VEGF-A high tumor-like microenvironment VEGF-A165 was cloned into human fibroblast cells (Additional file 4: Figure S3). The effects of VEGF-A were investigated by comparing aggregates with VEGF-Anormal and VEGF-A over-expressing (VEGF-Ahigh) fibroblasts (Additional file 5: Figure S4). Flow cytometric analysis revealed that high levels of VEGF-A lead to elevated Eng (CD105) expression on CD31+ endothelial cells (Fig. 4c, Additional file 6: Figure S5). To test whether Wnt5a can modulate VEGF-Ahigh microenvironment, 3D lung tissue aggregates containing VEGF-Anormal and VEGF-Ahigh fibroblasts were exposed to rhWnt5a. Flow cytometric analysis revealed that rhWnt5a did not block proliferation marker Eng (CD105) expression (Fig. 4c, Additional file 6: Figure S5) indicating that Eng (CD105) is not under Wnt5a control.Fig. 4


Increased Wnt5a in squamous cell lung carcinoma inhibits endothelial cell motility
The effect of Wnt5a on VEGF-A induced endothelial cell activation and motility. a, CD105 mRNA expression is significantly higher in primary AC compared to SCC samples. Error bars, SEM. One-way ANOVA, post hoc Bonferroni; n = 11 and n = 12 per groups. b, Flow cytometric analysis of CD105 protein expression in CD31 positive endothelial cells in primary AC and SCC samples. n = 6 per groups. c, Flow cytometric analysis of CD105 levels in normal and high VEGF-A microenvironment in 3D lung aggregate tissues has also shown an increase of activation marker CD105 in VEGF-Ahigh tissues. The double positive (CD105/CD31) cell population was considered as activated endothelial cells. Independent samples t-test, n = 6. 1 μg/ml rhWnt5a treatment had no effect on the VEGF-A induced endothelial cell activation measured by the double positive (CD105/CD31) cell population identified by flow cytometric analysis. Independent samples t-test, n = 6. d, Localization of endothelial cells was identified by immunoflurescent staining of CD31 and analyzed by confocal microscopy in 3D lung tissue aggregates. In VEGF-Anormal microenvironment endothelial cells remained diffuse in the tissue. Under VEGF-A excess endothelial cell migrated towards the source (VEGF-Ahigh fibroblasts) of the signal in the center of the aggregate tissue. 1 μg/ml rhWnt5a treatment of VEGF-Ahigh tissue aggregates inhibited endothelial cell accumulation in the center of the aggregate. Bar chart represents the quantification of endothelial cell distribution. Relative area of CD31+ endothelial cells are compared to total field. Percentages were calculated as relative area of endothelial cells/area of total field *100. Error bars; SEM. Independent samples t-test n = 3. Representative images of three independent experiments are shown. Scale bars, 50 μm. e, HMVEC-L transwell migration assay. Endothelial cells migrate significantly faster towards VEGF-Ahigh fibroblast, while 1 μg/ml rhWnt5a can reverse the effect of elevated VEGF-A level. Scale bar 100 μm. One-way ANOVA, n = 3. P < 0.05 was considered as significant, * p < 0.05, ** p < 0.01, *** p < 0.001
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Fig4: The effect of Wnt5a on VEGF-A induced endothelial cell activation and motility. a, CD105 mRNA expression is significantly higher in primary AC compared to SCC samples. Error bars, SEM. One-way ANOVA, post hoc Bonferroni; n = 11 and n = 12 per groups. b, Flow cytometric analysis of CD105 protein expression in CD31 positive endothelial cells in primary AC and SCC samples. n = 6 per groups. c, Flow cytometric analysis of CD105 levels in normal and high VEGF-A microenvironment in 3D lung aggregate tissues has also shown an increase of activation marker CD105 in VEGF-Ahigh tissues. The double positive (CD105/CD31) cell population was considered as activated endothelial cells. Independent samples t-test, n = 6. 1 μg/ml rhWnt5a treatment had no effect on the VEGF-A induced endothelial cell activation measured by the double positive (CD105/CD31) cell population identified by flow cytometric analysis. Independent samples t-test, n = 6. d, Localization of endothelial cells was identified by immunoflurescent staining of CD31 and analyzed by confocal microscopy in 3D lung tissue aggregates. In VEGF-Anormal microenvironment endothelial cells remained diffuse in the tissue. Under VEGF-A excess endothelial cell migrated towards the source (VEGF-Ahigh fibroblasts) of the signal in the center of the aggregate tissue. 1 μg/ml rhWnt5a treatment of VEGF-Ahigh tissue aggregates inhibited endothelial cell accumulation in the center of the aggregate. Bar chart represents the quantification of endothelial cell distribution. Relative area of CD31+ endothelial cells are compared to total field. Percentages were calculated as relative area of endothelial cells/area of total field *100. Error bars; SEM. Independent samples t-test n = 3. Representative images of three independent experiments are shown. Scale bars, 50 μm. e, HMVEC-L transwell migration assay. Endothelial cells migrate significantly faster towards VEGF-Ahigh fibroblast, while 1 μg/ml rhWnt5a can reverse the effect of elevated VEGF-A level. Scale bar 100 μm. One-way ANOVA, n = 3. P < 0.05 was considered as significant, * p < 0.05, ** p < 0.01, *** p < 0.001
Mentions: As VEGF-A has previously been determined to stimulate endothelial cell proliferation and migration [53], expression of endoglin (Eng or CD105) a transmembrane auxillary receptor for transforming growth factor-beta (TGF-beta) that is predominantly expressed on proliferating endothelial cells was also tested [54]. Analysis of primary SCC and AC tissue samples revealed that the endothelial cell proliferation marker Eng (CD105) was significantly lower in SCC compared to AC (Fig. 4a and b). Although VEGF-A was significantly higher than normal in both cancer subtypes, VEGF-A levels in SCC were lower than in AC (Fig. 1b). To be able to study the molecular effects of high VEGF-A levels on endothelial cells, in vitro studies were performed using a three dimensional (3D) human lung aggregate model tissue consisting of primary human small airway epithelial cells (SAEC), microvascular lung endothelial cells (HMVEC-L), and human fibroblasts (NHLF and F11) (Additional file 2: Figure S1). The 3D aggregate culture conditions provided close to natural, yet defined, cellular environment for molecular studies. qRT-PCR analysis of the lung model tissue aggregates revealed highly similar expression levels of angiogenic stimulators including VEGF-A, IL-1beta and HIF-1alpha to primary human lungs (Additional file 3: Figure S2) indicating that the model is suitable to study pro- and/or anti-angiogenic mechanisms. To recreate the VEGF-A high tumor-like microenvironment VEGF-A165 was cloned into human fibroblast cells (Additional file 4: Figure S3). The effects of VEGF-A were investigated by comparing aggregates with VEGF-Anormal and VEGF-A over-expressing (VEGF-Ahigh) fibroblasts (Additional file 5: Figure S4). Flow cytometric analysis revealed that high levels of VEGF-A lead to elevated Eng (CD105) expression on CD31+ endothelial cells (Fig. 4c, Additional file 6: Figure S5). To test whether Wnt5a can modulate VEGF-Ahigh microenvironment, 3D lung tissue aggregates containing VEGF-Anormal and VEGF-Ahigh fibroblasts were exposed to rhWnt5a. Flow cytometric analysis revealed that rhWnt5a did not block proliferation marker Eng (CD105) expression (Fig. 4c, Additional file 6: Figure S5) indicating that Eng (CD105) is not under Wnt5a control.Fig. 4

View Article: PubMed Central - PubMed

ABSTRACT

Background: Angiogenesis is important both in normal tissue function and disease and represents a key target in lung cancer (LC) therapy. Unfortunately, the two main subtypes of non-small-cell lung cancers (NSCLC) namely, adenocarcinoma (AC) and squamous cell carcinoma (SCC) respond differently to anti-angiogenic e.g. anti-vascular endothelial growth factor (VEGF)-A treatment with life-threatening side effects, often pulmonary hemorrhage in SCC. The mechanisms behind such adverse reactions are still largely unknown, although peroxisome proliferator activator receptor (PPAR) gamma as well as Wnt-s have been named as molecular regulators of the process. As the Wnt microenvironments in NSCLC subtypes are drastically different, we hypothesized that the particularly high levels of non-canonical Wnt5a in SCC might be responsible for alterations in blood vessel growth and result in serious adverse reactions.

Methods: PPARgamma, VEGF-A, Wnt5a, miR-27b and miR-200b levels were determined in resected adenocarcinoma and squamous cell carcinoma samples by qRT-PCR and TaqMan microRNA assay. The role of PPARgamma in VEGF-A expression, and the role of Wnts in overall regulation was investigated using PPARgamma knock-out mice, cancer cell lines and fully human, in vitro 3 dimensional (3D), distal lung tissue aggregates. PPARgamma mRNA and protein levels were tested by qRT-PCR and immunohistochemistry, respectively. PPARgamma activity was measured by a PPRE reporter system. The tissue engineered lung tissues expressing basal level and lentivirally delivered VEGF-A were treated with recombinant Wnts, chemical Wnt pathway modifiers, and were subjected to PPARgamma agonist and antagonist treatment.

Results: PPARgamma down-regulation and VEGF-A up-regulation are characteristic to both AC and SCC. Increased VEGF-A levels are under direct control of PPARgamma. PPARgamma levels and activity, however, are under Wnt control. Imbalance of both canonical (in AC) and non-canonical (in SCC) Wnts leads to PPARgamma down-regulation. While canonical Wnts down-regulate PPARgamma directly, non-canonical Wnt5a increases miR27b that is known regulator of PPARgamma.

Conclusion: During carcinogenesis the Wnt microenvironment alters, which can downregulate PPARgamma leading to increased VEGF-A expression. Differences in the Wnt microenvironment in AC and SCC of NSCLC lead to PPARgamma decrease via mechanisms that differentially alter endothelial cell motility and branching which in turn can influence therapeutic response.

Electronic supplementary material: The online version of this article (doi:10.1186/s12885-016-2943-4) contains supplementary material, which is available to authorized users.

No MeSH data available.