Latent effects of fibronectin, α5β1 integrin, αVβ5 integrin and the cytoskeleton regulate pancreatic carcinoma cell IL-8 secretion

Abstract

Interactions between tumour cells and the microenvironment are increasingly recognised to have an influence on cancer progression. In pancreatic carcinoma, a highly desmoplastic stroma with abnormal extracellular matrix (ECM) protein and interleukin-8 (IL-8) expression is seen. To investigate whether the ECM may further contribute to abnormalities in the microenvironment by influencing IL-8 secretion, we cultured the Mia PaCa2 pancreatic carcinoma cell line on fibronectin. This resulted in a dose-dependent increase in IL-8 secretion, which was RGD dependent and accompanied by cell spreading and proliferation. The role of spreading was assessed by disruption of the cytoskeleton with cytochalasin D, resulting in a large increase in IL-8 secretion, which was reduced from 31- to 24-fold by fibronectin. This remarkable response was associated with inhibition of spreading and proliferation and represents a novel cytoskeletal function. To investigate whether it could be accounted for by the loss of integrin-mediated signalling, the expressed α5β1, αVβ5 and α3β1 integrins were inhibited. α5β1 inhibition prevented spreading and proliferation but produced a much smaller rise in IL-8 secretion than cytochalasin D. αVβ5 inhibition alone had only minor effects but when inhibited in combination with α5β1 completely abolished the response to fibronectin. These results reveal latent stimulatory effects of the αVβ5 integrin on IL-8 secretion and suggest that integrin crosstalk may limit the induction of IL-8 secretion by fibronectin. However, the magnitude of IL-8 secretion induced by cytochalasin cannot be accounted for by integrin signalling and may reflect the influence of another signalling pathway or a novel, intrinsic cytoskeletal function.

Tumor-stroma interactions in pancreatic ductal adenocarcinoma

“…However, this effect could not be accounted for by anti-integrin antibodies inhibiting integrins a 5 h 1 or a v h 5 alone but when inhibited in combination completely abolished the response to fibronectin. These results suggest a latent stimulatory effect of a v or a 5 h 5 integrin on IL-8 secretion and provide evidence that integrin cross-talk may limit the induction of IL-8 secretion by fibronectin (23). However, the magnitude of IL-8 secretion cannot be explained solely by a fibronectin-integrin -driven process, and other signaling pathways, such as TGFh and IL-10, are implicated (24).…”

Anti-CD146 monoclonal antibody AA98 inhibits angiogenesis via suppression of nuclear factor-κB activation

“…An important early event in the development of metastasis is angiogenesis. Most tumor cells secrete a variety of cytokines and proangiogenic molecules, such as fibroblast growth factors, vascular endothelial growth factors (1), IL-8 (2), and extracellular matrix proteinases (3), which promote angiogenesis and metastasis. Although the mechanisms for these factors regulating cell metastasis and angiogenesis are largely undefined, many studies have shown that the pleiotropic transcription factor nuclear factor nB (NF-nB) can be activated by the cytokines from tumors and that NF-nB plays an important role in the control of tumor metastasis, angiogenesis, and hence, oncogenesis (4).…”

Cancer cell angiogenic capability is regulated by 3D culture and integrin engagement

“…Tumor vascularization is mediated by an overbalance of proangiogenic molecules that may be caused by dysregulated cell-ECM interactions (5). Vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and IL-8, in particular, have been widely investigated for their role in tumor vascularization, and their signaling is regulated by both cell-ECM interactions and 3D culture conditions (3,6,7). Because integrin engagement with ECM molecules is differentially regulated in 2D relative to 3D culture (3,8), it is likely that these changes underlie the tumor angiogenic switch.…”