A Nexus Consisting of Beta-Catenin and Stat3 Attenuates BRAF Inhibitor Efficacy and Mediates Acquired Resistance to Vemurafenib

作者：Sinnberg Tobias; Makino Elena; Krueger Marcel A; Velic Ana; Macek Boris; Rothbauer Ulrich; Groll Nicola; Poetz Oliver; Czemmel Stefan; Niessner Heike; Meier Friedegund; Ikenberg Kristian; Garbe Claus; Schittek Birgit

来源：EBioMedicine, 2016, 8: 132-149.

DOI：10.1016/j.ebiom.2016.04.037

• beta-catenin
• Melanoma
• BRAF
• Stat3
• Resistance
• Vemurafenib

Acquired resistance to second generation BRAF inhibitors (BRAFis), like vemurafenib is limiting the benefits of long term targeted therapy for patients with malignant melanomas that harbor BRAF V600 mutations. Since many resistance mechanisms have been described, most of them causing a hyperactivation of the MAPK-or PI3K/AKT signaling pathways, one potential strategy to overcome BRAFi resistance in melanoma cells would be to target important common signaling nodes. Known factors that cause secondary resistance include the overexpression of receptor tyrosine kinases (RTKs), alternative splicing of BRAF or the occurrence of novel mutations in MEK1 or NRAS.
In this study we show that beta-catenin is stabilized and translocated to the nucleus in approximately half of the melanomas that were analyzed and which developed secondary resistance towards BRAFi. We further demonstrate that beta-catenin is involved in the mediation of resistance towards vemurafenib in vitro and in vivo. Unexpectedly, beta-catenin acts mainly independent of the TCF/LEF dependent canonical Wnt-signaling pathway in resistance development, which partly explains previous contradictory results about the role of beta-catenin in melanoma progression and therapy resistance. We further demonstrate that beta-catenin interacts with Stat3 after chronic vemurafenib treatment and both together cooperate in the acquisition and maintenance of resistance towards BRAFi.

• 出版日期2016-6