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Therapeutic targeting of the focal adhesion complex prevents oncogenic TGF-beta signaling and metastasis.

ABSTRACT: Mammary tumorigenesis is associated with the increased expression of several proteins in the focal adhesion complex, including focal adhesion kinase (FAK) and various integrins. Aberrant expression of these molecules occurs concomitant with the conversion of TGF-beta function from a tumor suppressor to a tumor promoter. We previously showed that interaction between beta3 integrin and TbetaR-II facilitates TGF-beta-mediated oncogenic signaling, epithelial-mesenchymal transition (EMT), and metastasis. However, the molecular mechanisms by which the focal adhesion complex contributes to beta3 integrin:TbetaR-II signaling and the oncogenic conversion of TGF-beta remain poorly understood.FAK expression and activity were inhibited in normal and malignant mammary epithelial cells (MECs) either genetically by using lentiviral-mediated delivery of shRNAs against FAK, or pharmacologically through in vitro and in vivo use of the FAK inhibitors, PF-562271 and PF-573228. Altered Smad2/3 and p38 MAPK activation, migration, EMT, and invasion in response to TGF-beta1 were monitored in FAK-manipulated cells. TbetaR-II expression was increased in metastatic breast cancer cells by retroviral transduction, and the metastasis of FAK- and TbetaR-II-manipulated tumors was monitored by using bioluminescent imaging.TGF-beta stimulation of MECs stabilized and activated FAK in a beta3 integrin- and Src-dependent manner. Furthermore, by using the human MCF10A breast cancer progression model, we showed that increased FAK expression in metastatic breast cancer cells mirrored the acquisition of enhanced activation of p38 MAPK by TGF-beta. Administering FAK inhibitors or rendering metastatic breast cancer cells FAK deficient abrogated the interaction between beta3 integrin and TbetaR-II, thereby preventing TGF-beta from (a) activating p38 MAPK; (b) stimulating MEC invasion, migration, and EMT; and (c) inducing early primary tumor dissemination to the lungs. Finally, in contrast to FAK depletion, adjuvant FAK chemotherapy of mammary tumors decreased their growth in part by diminished macrophage tumor infiltration.Our studies identify an essential function for FAK in mediating the interaction between beta3 integrin and TbetaR-II, and thus in facilitating the oncogenic conversion of TGF-beta required for mammary tumor metastasis. Furthermore, this study establishes chemotherapeutic targeting of FAK as an effective, two-pronged approach in preventing tumor progression both by decreasing innate immune cell infiltration, and by inhibiting early TGF-beta-dependent metastasis.

SUBMITTER: Wendt MK

PROVIDER: S-EPMC2790843 | biostudies-other | 2009

REPOSITORIES: biostudies-other

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Therapeutic targeting of the focal adhesion complex prevents oncogenic TGF-beta signaling and metastasis.

Wendt Michael K MK Schiemann William P WP

Breast cancer research : BCR 20090101 5

<h4>Introduction</h4>Mammary tumorigenesis is associated with the increased expression of several proteins in the focal adhesion complex, including focal adhesion kinase (FAK) and various integrins. Aberrant expression of these molecules occurs concomitant with the conversion of TGF-beta function from a tumor suppressor to a tumor promoter. We previously showed that interaction between beta3 integrin and TbetaR-II facilitates TGF-beta-mediated oncogenic signaling, epithelial-mesenchymal transiti ...[more]

PMID: 19740433

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Project description:All-trans retinoic acid (RA), the primary metabolite of vitamin A, controls the development and homeostasis of organisms and tissues. RA and its natural and synthetic derivatives, both known as retinoids, are promising agents in treating and chemopreventing different neoplasias, including breast cancer (BC). Focal adhesion kinase (FAK) is a crucial regulator of cell migration, and its overexpression is associated with tumor metastatic behavior. Thus, pharmaceutical FAK inhibitors (FAKi) have been developed to counter its action. In this work, we hypothesize that the RA plus FAKi (RA + FAKi) approach could improve the inhibition of tumor progression. By in silico analysis and its subsequent validation by qPCR, we confirmed RARA, SRC, and PTK2 (encoding RARα, Src, and FAK, respectively) overexpression in all breast cells tested. We also showed a different pattern of genes up/down-regulated between RA-resistant and RA-sensitive BC cells. In addition, we demonstrated that both RA-resistant BC cells (MDA-MB-231 and MDA-MB-468) display the same behavior after RA treatment, modulating the expression of genes involved in Src-FAK signaling. Furthermore, we demonstrated that although RA and FAKi administered separately decrease viability, adhesion, and migration in mammary adenocarcinoma LM3 cells, their combination exerts a higher effect. Additionally, we show that both drugs individually, as well as in combination, induce the expression of apoptosis markers such as active-caspase-3 and cleaved-PARP1. We also provided evidence that RA effects are extrapolated to other cancer cells, including T-47D BC and the human cervical carcinoma HeLa cells. In an orthotopic assay of LM3 tumor growth, whereas RA and FAKi administered separately reduced tumor growth, the combined treatment induced a more potent inhibition increasing mice survival. Moreover, in an experimental metastatic assay, RA significantly reduced metastatic lung dissemination of LM3 cells. Overall, these results indicate that RA resistance could reflect deregulation of most RA-target genes, including genes encoding components of the Src-FAK pathway. Our study demonstrates that RA plays an essential role in disrupting BC tumor growth and metastatic dissemination in vitro and in vivo by controlling FAK expression and localization. RA plus FAKi exacerbate these effects, thus suggesting that the sensitivity to RA therapies could be increased with FAKi coadministration in BC tumors.

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Therapeutic targeting of the focal adhesion complex prevents oncogenic TGF-beta signaling and metastasis.

Publications

Therapeutic targeting of the focal adhesion complex prevents oncogenic TGF-beta signaling and metastasis.

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