Loss of AF6/afadin, a marker of poor outcome in breast cancer, induces cell migration, invasiveness and tumor growth.

Abstract

Afadin/AF6, an F-actin-binding protein, is ubiquitously expressed in epithelia and has a key role during development, through its regulatory role in cell-cell junction organization. Afadin loss of expression in 15% of breast carcinoma is associated with adverse prognosis and increased risk of metastatic relapse. To determine the role of afadin in breast cancer, we studied the functional consequences of afadin protein extinction using in vitro and in vivo models. Three different breast cancer cell lines representative of the major molecular subtypes were stably repressed for afadin expression (knockdown of afadin (afadin KD)) using RNA interference. Collective and individual migrations as well as Matrigel invasion were markedly increased in afadin KD cells. Heregulin-β1 (HRG-β1)-induced migration and invasion were increased by twofold in afadin KD cells. Conversely, ectopic expression of afadin in the afadin-negative T47D cell line inhibited spontaneous and HRG-β1-induced migrations. RAS/MAPK and SRC kinase pathways were activated in afadin KD cells. Activation levels positively correlated with migration and invasion strength. Use of MEK1/2 (U0126) and SRC kinases (SU6656) inhibitors reduced afadin-dependent migration and invasion. Afadin extinction in the SK-BR-3 cell line markedly accelerated tumor growth development in mouse mammary gland and lung metastasis formation. These results may explain why the loss of afadin expression in tumors correlates with high tumor size and poor metastasis-free survival in patients.

• Authors: G Fournier, O Cabaud, E Josselin, A Chaix, J Adélaïde, D Isnardon, A Restouin, R Castellano, P Dubreuil, M Chaffanet, D Birnbaum, M Lopez
• Journal: Oncogene (Oncogene) Vol. 30 Issue 36 Pg. 3862-74 (Sep 08 2011) ISSN: 1476-5594 [Electronic] England
• PMID: 21478912 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• AFDN protein, human
• Afdn protein, mouse
• Microfilament Proteins
• afadin
• Myosins
• Kinesins

Topics

• Animals
• Breast Neoplasms (metabolism, therapy)
• Cell Line, Tumor
• Cell Movement
• Cell Proliferation
• Female
• Gene Expression Regulation, Neoplastic
• Humans
• Kinesins (metabolism)
• MAP Kinase Signaling System
• Mice
• Mice, Inbred NOD
• Mice, SCID
• Microfilament Proteins (metabolism)
• Myosins (metabolism)
• Neoplasm Invasiveness
• Neoplasm Transplantation
• Prognosis
• RNA Interference
• Treatment Outcome