Increased Wnt5a in squamous cell lung carcinoma inhibits endothelial cell motility

Abstract

BackgroundAngiogenesis 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.MethodsPPARgamma, 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.ResultsPPARgamma 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.ConclusionDuring 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 materialThe online version of this article (doi:10.1186/s12885-016-2943-4) contains supplementary material, which is available to authorized users.

rSjP40 protein promotes PPARγ expression in LX‐2 cells through microRNA‐27b

“…miR-27b mimic also partially reverses rSjP40induced up-regulation of PPARg expression in LX-2 cells. In addition, we found that rSjP40 and miR-27b regulate the luciferase activity of PPRE luciferase reporter because the activity of the PPRE responsive element can be activated by PPARg activation (25). miR-27b mimic did not suppress the lipid droplet storage in LX-2 cells induced by rSjP40 (data not shown).…”

Cigarette Smoke-Induced Pulmonary Inflammation Becomes Systemic by Circulating Extracellular Vesicles Containing Wnt5a and Inflammatory Cytokines

“…Mostly, if the canonical or beta-catenin-dependent Wnt pathway is up-regulated, PPAR gamma is down-regulated ( 27 – 29 ). Additionally, PPAR gamma is also a non-canonical Wnt pathway target and is involved in the regulation of blood vessel growth via a non-canonical Wnt5a-dependent mechanism ( 30 ). Interestingly, Wnt5a is also a strong pro-inflammatory molecule that has been reported as a potent activator of cigarette smoke-induced inflammatory cytokine expression ( 30 – 32 ) and is characteristically up-regulated in squamous cell carcinomas ( 30 ).…”

“…Additionally, PPAR gamma is also a non-canonical Wnt pathway target and is involved in the regulation of blood vessel growth via a non-canonical Wnt5a-dependent mechanism ( 30 ). Interestingly, Wnt5a is also a strong pro-inflammatory molecule that has been reported as a potent activator of cigarette smoke-induced inflammatory cytokine expression ( 30 – 32 ) and is characteristically up-regulated in squamous cell carcinomas ( 30 ). Cigarette smoke (CS) is also the initial trigger of macrophage activation ( 33 ) and macrophage polarization toward the classical M1 and the alternative M2 lineages ( 34 ).…”

The role of developmental signaling pathways in non-small cell lung carcinoma

“…Future studies could consider several different aspects that have been explored in this review. Firstly, distinct NSCLC subtypes, should be observed and tackled differently; for instance, considerable differences exist between the response of SCC and AC cell lines to targeted therapies due to differential activation of the Notch pathway or the higher microvessel density present in AC [106]. Notably, as mentioned in a previous section of this thesis, Notch receptors have been found to have a higher predictive value for AC and this finding should be taken into account in future studies.…”

“…In one study, Wnt5a expression was found in 61.95% of NSCLC cases analyzed; it was mostly correlated with SCC, male sex and shorter OS and it was also associated with vascular mimicry and microvessel density [105]. Wnt-5 can contribute to angiogenesis by increasing microvessel formation via downregulation of peroxisome proliferator-activated receptor-gamma (PPARγ) and upregulation of VEGF-A expression [106]. Additionally, the ligand can contribute to EMT by downregulating β -catenin levels and other attachment proteins in the AC cell line H1975 [107].…”