tumour hypoxia - detection and prognostic significance

METOXIA CourseTumor hypoxia

- detection and prognostic significanceHeidi Lyng

Thursday 11 October 2012

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

Learning objectives

• Why does hypoxia arise in tumors?

• How can we measure tumor hypoxia in patients?

• What is the clinical importance of tumor hypoxia?


Tumor development


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


Thomlinson & Gray, 1955

Vascularizedstroma

Tumor cells

Necrosis

Pioneer work from 1955Thomlinson and Gray describe corded structures in tumors

Hypothesis: cells bordering necrosis were viable, but hypoxic

Hypoxia

Oxygen concentrations

• Radiobiological hypoxia: < 0.5% O2 (4 mmHg)

• Activation of hypoxia inducible factor 1 (HIF1): < 1% O2 (7-8 mmHg)

• Important clinically: < 1.5% O2 (10 mmHg)This course is funded with the support of the METOXIA project

under the FP7 Programme.

Air: 21% O2 (160 mmHg)Normal tissue: 5-9% O2 (40 - 75mmHg)Hypoxia: < 3% O2 (0 - 20 mmHg)

Why does hypoxia arise in tumors?


Tumors: imbalance between oxygen supply and demand

Oxygen supply Oxygen demand

Normal tissue

Tumor

Oxygen imbalance in tumors

• Poor oxygen supply - Inefficient vascular network - Low oxygen saturation of hemoglobin (HbO2)

• High oxygen demand - High metabolic activity


Oxygen

Tumor vascular network


Tumor grown in a window chamber

Dewhirst et al. Radiother Oncol 2007

Microscopy of living tissue

Irregular vascular network in tumors

Oxygen saturation of hemoglobin


Hardee et al, Curr Mol Med 2009

Tumor grown in a window chamber

Heterogeneous and often low oxygen saturation in tumors

Cycling (acute, transient) hypoxia


Hardee et al., Curr Mol Med 2009

Fluctuations in red cell flux and oxygen saturation in tumor vessels

Hemoglobin oxygen saturation (%)

Time (min)

Why is hypoxia an adverse factor?


TUMOR HYPOXIA

Genomicinstability

Radioresistance

Metastasis, treatment resistance, malignant progression

Chemoresistance

Selection pressure by apoptosis

Poor clinical outcome

InvasionAngiogenesis


Hypoxia-induced radioresistance

Oxygen: more damage, damage fixation

Hypoxia increases the radioresistance of tumor cells

Detection of tumor hypoxia in patients

• Oxygen tension (pO2) electrodes

• Immunohistochemistry markers

• Gene signatures

• Imaging


PO2 electrodes


PO2 oxygen concentration ”Gold standard”Invasive


Lyng et al. Radiother Oncol 1997

PO2 in human tumors: lower than in normal tissues varies within the tumor varies from tumor to tumor

PO2 measurements50


PO2 measurementsMulti-center study of 397 head and neck tumors

Nordsmark et al. Radiother Oncol 2005

P = 0.006

Less hypoxic

More hypoxic

Poor outcome of patients with hypoxic head and neck tumor

Immunohistochemistry markers

• Pimonidazole, EF5

• Hypoxia-inducible proteins


Cell type and compartment informationInvasive

Pimonidazole


Mod from Varia et al. Gyn Oncol 1998

HYPOXIA

Requires administration of pimonidazole

Pimonidazole


Lyng , unpublished

Pimonidazole staining of melanoma xenograft

Necrosis

Hypoxia-inducible proteins


Proteins upregulated under hypoxia are potential immunohistochemistry markers

VEGF (angiogenesis) CA9 (pH)

GLUT1 (metabolism)

Key transcription factor:Hypoxia-inducible factor HIF1

HIF1 regulation

HIF1α staining


Lyng, unpublished

HIF1α staining of cervical carcinoma

Necrosis

Multimarker staining


Rademakers et al. BMC Cancer 2011PimoHIF1CA9

Staining of head and neck carcinoma

Gene signatures


Tumor

DNA

mRNA

Protein

Whole genome screening of mRNAs

(gene expressions)

Can include genes from several pathwaysInvasive

Gene signature

Gene signatures


High gene expression

Low gene expression

Poor outcome of patients with high expression of signature genes

Hypoxia gene signature of cervical tumors

Halle et al. Cancer Research 2012

31 hypoxia inducible genes in:

MetabolismCell cycle regulationProliferation

Imaging

• Dynamic contrast enhanced (DCE) MR imaging


Information on the entire tumor and its heterogeneityNon-invasive but requires administration of contrast agent


DCE-MR imaging of tumor hypoxia


HIF1

Less hypoxic cervical tumor

HIF1

Hypoxic cervical tumor


Prognostic significance

• Head and neck cancer, cervical cancer: - pO2 electrodes, pimonidazole, hypoxia-inducible proteins,

hypoxia gene signature, imaging

• Prostate cancer, soft tissue sarcomas: - pO2 electrodes

• Breast cancer, ovarian cancer: - hypoxia-inducible proteins, hypoxia gene signature


Some cancer types and methods

Tumor hypoxia – key points

• Arises due to a higher oxygen demand than supply • Can be chronic or cycling (acute, transient)

• Promotes metastasis, treatment resistance and malignant progression

• Has been studied extensively in patients by complementary methods with different strengths and weaknesses

• Is related to poor clinical outcome of many cancer diseases


tumour hypoxia - detection and prognostic significance

Documents

fp7 programme

metoxia projectunder

mmhg hypoxia

tumorsthis course

tumor vesselsthis course

mmhgthis course

detection of tumor hypoxia

neck tumorthis course