Hypoxia (HIF-1) as a major target of cancer therapy

By,Prabhu Thirusangu,Molecular Biomedicine Laboratory,Sahyadri Science College,Kuvempu University,Shimoga, KA

                    

Tumor development

This course is funded with the support of the METOXIA project under the FP7 Programme.

Metastases

SpreadingInvasive growth

Therapy

Normal cell

Transformation

Cancer cell

Gene defectsSteps in carcinogenesis

Angiogenesis

Tumor

Hypoxia

Angiogenesis: growth of blood vessels

Uncontrolled cell growthAnti-apoptosis

Cell population

Apoptosis: programmed cell death

The response of Hypoxia to Oxygen

Structure of HIF-1

Dayan et al, Cancer Microenvironment (2008)

Structure of HIF-α & β

Dayan et al, Cancer Microenvironment (2008)

Garth Powis et al, Mol Cancer Ther 2004

Hypoxia signaling..

Importin α,β

Proteosomal degradation of HIF-1α

Luo et al, 2014 BioMed Research International

Proteosomal degradation of HIF-1α

Dayan et al, Cancer Microenvironment (2008)

Stabilization of HIF-1α

Soon-Sun Hong, et al, Cancer Research and Treatment 2004

Nuclear Accumulation of HIF-1α

PPhosphorilation by MAPK etc

P

Luo et al, 2014 BioMed Research International

HIF-1

hypoxia

Pol IIcomplexCBP/p300

HIF-1

HIF-1

Angiogenesis Glucosemetabolism

Cellproliferation

HIF-1 is a heterodimer

Wang et al

B

VHLC

Cul-2

HIFproteasome

PHD

HIF

HRE

VHL targets HIF for ubiquitination PHDs hydroxylate HIF

O2

O2

O2

O2

O2

HIF :activates genes involved in O2 homeostasis

Regulation of Hypoxia Inducible Genes

Holterman & Stephen Lee et al

O2

O2

O2

O2

O2

B

VHLC

Cul-2

HIF

proteasome

PHD

HIF

HRE

ub-HIF exported to cytoplasm for degradation

Regulation of Hypoxia Inducible Genes

Holterman & Stephen Lee et al

B

VHLC

Cul-2

proteasome

PHD

HIF

HRE

HIF

PHDs are inactivated in low oxygen tension HIF evades recognition by VHL and binds HIF

O2

O2

O2

O2

O2

Regulation of Hypoxia Inducible Genes

Holterman & Stephen Lee et al

HIF evades recognition by VHL and binds HIF

B

VHLC

Cul-2

proteasome

PHD

HIF HIF

Glut-1VEGFMMPTGF

HRE

HIF heterodimers activate hypoxia inducible genes

O2

Regulation of Hypoxia Inducible Genes

Holterman & Stephen Lee et al

Dayan et al, Cancer Microenvironment (2008)

From the ECM to HIF and from HIF to the ECM…

eIF-4E

Dayan et al, Cancer Microenvironment (2008)

From oxygen to HIF and from HIF to oxygen.

From nutrients to HIF and from HIF to metabolism

Dayan et al, Cancer Microenvironment (2008)

Soon-Sun Hong, et al, Cancer Research and Treatment 2004

Zimna et al, BioMed Research International 2014

HIF inhibitors could be tentatively divided in agents that modulate:

(1) HIF-1 mRNA expression,

(2) HIF-1 protein translation,

(3) HIF-1 protein degradation,

(4) HIF-1 nuclear translocation

(5) HIF-1 dimerization and DNA binding

(6) HIF-1 transcriptional activity.

Possible targets on Hypoxia signaling..

Points to be remembered….

A. What is HIF-1?

The studies of hypoxia response element of the erythropoietin gene leads to the discovery of HIF-1 by Semenza and Wang in 1992. Semenza GL & Wang GL. (1992). Mol. Cell. Biol. 12: 5447-5454.

HIF-1: Hypoxia Inducible Factor - 1

HIF-1 is a protein with DNA binding activity. It is composed of two subunits: HIF-1 and HIF-1.

Proline residue 402 & 564 in HIF-1 can be hydroxylated by prolyl hydroxylase.

The hydroxylation of proline causes the binding of von Hippel-Lindau tumor suppressor (VHL).

The binding of VHL leads to the ubiquitinylation of HIF-1.

Ubiquitinylation of HIF-1 results in degradation by proteasome. Bruick RK. (2002) Science. 295:807-808.

HIF-1 is constitutively made and degraded via VHL.

Prolyl hydroxylase is O2-dependent The activation of prolyl hydroxylase depends on

several co-factors such as O2, Fe2+, 2-OG, -ketoglutarate and ascorbate.

Under hypoxia, prolyl hydroxylase cannot be activated. Thus,

HIF-1 accumulates and translocates into nucleus. In the nucleus, it binds to HIF-1 forming HIF-1. HIF-1 binds to co-activators CBP/p300 and is then activated.

HIF-1 Target GenesErythropoeitin (EPO)Nitric oxide synthase 2 (NOS2)TransferrinTransferrin receptorVascular endothelial growth factor (VEGF)VEGF receptor FLT-1

Group 1: O2 Delivery

Aldolase AAldolase CEnolase 1 (ENO1) Glucose transporter 1Glyceraldehyde phosphate dehydrogenase Hexokinase 1Hexokinase 2Lactate dehydrogenase APhosphofructokinase LPhosphoglycerate kinase 1Pyruvate kinase M

Group 2: Glucose/Energy Metabolism

Insulin-like growth factor 2 (IGF-2)IGF binding protein 1IGF binding protein 3p21p35

Group 3: Cell Proliferation/Viability

Finally…Thank you.

Special Thanks to Dr. Wang for providing presentation skeleton