Oncotarget

Research Papers:

Suppression of FGFR3- and MYC-dependent oncogenesis by tubacin: association with HDAC6-dependent and independent activities

Sara Ota, Zi-Qiang Zhou and Peter J. Hurlin _

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Oncotarget. 2018; 9:3172-3187. https://doi.org/10.18632/oncotarget.22816

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Abstract

Sara Ota1, Zi-Qiang Zhou1 and Peter J. Hurlin1,2

1Shriners Hospitals for Children Portland, Portland, OR 97239, USA

2Department of Cell, Developmental and Cancer Biology and Knight Cancer Institute, Oregon Health & Science University, Portland, OR 97239, USA

Correspondence to:

Peter J. Hurlin, email: [email protected]

Keywords: fibroblast growth factor receptor (FGFR); histone deacetylase 6 (HDAC6); MYC; cyclin D1; DNA damage

Received: September 24, 2017     Accepted: November 09, 2017     Published: December 01, 2017

ABSTRACT

Fibroblast growth factor receptor 3 (FGFR3) is amplified, translocated or mutated in a number of different human cancer types, but most commonly in bladder cancers. We previously found that the accumulation of FGFR3 is dependent on histone deacetylase 6 (HDAC6). Here we show that HDAC6 loss or inhibition reduces FGFR3 accumulation in cells made tumorigenic by ectopic expression of a mutant activated version of FGFR3 together with the MYC oncoprotein and in a bladder cancer cell line whose tumorigenicity is dependent on expression of a translocated version of FGFR3. In tumor xenoplant assays, HDAC6 deficiency or small molecule inhibition by the selective HDAC6 inhibitors tubacin or tubastatin A was found to significantly impede tumor growth. However, tubacin was more effective at inhibiting tumor growth than tubastatin A or HDAC6 deficiency. The superior anti-tumor activity of tubacin was linked to its ability to not only inhibit accumulation of mutant FGFR3, but also to cause robust downregulation of MYC and cyclin D1, and to induce a DNA damage response and apoptosis. Neither HDAC6 deficiency nor treatment with tubastatin A altered MYC or cyclin D1 levels, and neither induced a DNA damage response or apoptosis. Thus while tubacin and tubastatin A inhibit HDAC6 with similar selectivity and potency, our results reveal unique HDAC6-independent activities of tubacin that likely contribute to its potent anti-tumor activity.


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