A TWIST1-MLL-WDR5-HOTTIP Complex RegulatesHOXA9 Chromatin to Facilitate Metastasis of

Prostate Cancer

Rajendra P. Gajula1, Russell D. Williams1, Reem Malek1, Katriana Nugent1, Amanda J. Walker1, Sivarajan T. Chettiar1, Hailun

Wang1, Kekoa Taparra1, Jessica cades1, Joseph M. Herman1 and Phuoc T. Tran1

Hoxa9 is Necessary for Twist1 Phenotypes

Introduction:EMT and Twist1

Involvement of Hoxa9 Mechanism Conclusions/

Future Work

Summary: Hoxa9

Introduction:EMT and Twist1

Involvement of Hoxa9 Mechanism Conclusions/

Future Work

Phenotype Twist-shHoxa9 Hoxa9 Overexpression

EMT Markers -- Partial Induction

Migration Decreased Increased

Invasion Decreased Inceased

Anoikis Resistance Decreased Pending

Clonogenicity Decreased Increased

Soft Agar Decreased No Effect

Histone Methyltransferase Complexes

• Histone modifications:– H3K27: silencing– H3K4: activation– H3K79: ambiguous, but

known to activate Hoxa9 transcription

– Bivalence: both activating and silencing modifications present.

Introduction:EMT and Twist1

Involvement of Hoxa9 Mechanism Conclusions/

Future Work

Nature Reviews Molecular Cell Biology 6, 838-849 (November 2005)

HOTTIP: A lincRNA That Regulates the HOXA Cluster

Introduction:EMT and Twist1

Involvement of Hoxa9 Mechanism Conclusions/

Future Work

Wang et. al. Nature 472:120 (2011)

• HOTTIP is a lincRNA encoded by a gene in the 5’ region of the HOXA cluster.

• HOTTIP activates the HOXA cluster posterior genes via an interaction with an MLL-WDR5 histone methyltransferase complex that increases H3K4me3 activation marks.

Does Involvement of Hoxa9 Suggest a Role for histone methyltransferases?

Introduction:EMT and Twist1

Involvement of Hoxa9 Mechanism Conclusions/

Future Work

• MLL2 (encoded by KTM2D) mutations common in lethal, castration resistant prostate cancers.

• MLL2 is a histone methyltransferase.

• In AML, MLL2 mutations are common, and Hoxa9 overexpression is required for survival of MLL2-mutant cells.

Proposed Mechanism

Introduction: EMT and Twist1

Involvement of Hoxa9 Mechanism Conclusions/

Future Work

Summary: Hoxa9 Mediates Twist1 Induction of EMT Phenotype• Twist1 expression induces aggressive metastatic

phenotype in prostate cancer through EMT.• Structure-function mutants modulate intensity of Twist1-

induced phenotype.• Gene expression analysis of structure-function mutants

suggested role for Hoxa9.• Hoxa9 is necessary for induction of Twist1-induced EMT

phenotype.• Twist1 interacts with HOTTIP and a MLL-WDR5

methyltransferase complex to regulate Hoxa9 chromatin and expression by increasing H3K4me3 chromatin marks.

Introduction:EMT and Twist1

Involvement of Hoxa9 Mechanism Conclusions/

Future Work