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Posts Tagged ‘Hanahan’

Whitley Hypoxystation

Hypoxia and the Hallmarks of Cancer: Metabolic Reprogramming

Hanahan and Weinberg’s seminal papers on the Hallmarks of Cancer describe how cancer cells accommodate the frenzied growth characteristic of tumours. Low oxygen is eminently characteristic of tumours, and in this hypoxic environment, metabolism is reprogrammed to satisfy energetic and synthetic needs of the cells.


Our series on Hypoxia and the Hallmarks of Cancer has showcased research on how hypoxia in the tumour microenvironment affects 8 of the Hallmarks, and in the fifth and final chapter, we look more closely at how researchers are using the Hypoxystation to delineate the Hallmark Metabolic Reprogramming.

The Hypoxystation creates authentic cell culture conditions with regard to oxygen, CO2, temperature, and humidity.  Glove-less access to culture and manipulate cells under physiological atmosphere, in a HEPA-clean environment, allows cancer researchers to re-create the hypoxic tumour microenvironment. Hypoxystation user Dr Ali Tavassolli states that “We have only ever used the H35. I like the ease with which we can regulate and change the oxygen concentration”. And our user Dr. Brad Wouters at the Princess Margaret Cancer Centre in Toronto, who recently purchased his fourth Hypoxystation, says, “The continuous hypoxia we achieve in the workstation is a prerequisite for studies with hypoxia-activated drugs used in cancer therapy strategies.”

Hallmarks of Cancer

Metabolic Reprogramming

Changes in energy metabolism feature prominently in aggressive malignancy, and tumour hypoxia and the responding signalling pathways, featuring many HIF target genes, clearly interface with reprogrammed tumour metabolism. Reprogramming of conventional metabolic pathways serves to satisfy burgeoning energetic and anabolic needs of the tumour cells; many cancer cells may preferentially utilise glycolysis over oxidative phosphorylation, uncoupling mitochondrial metabolism from oxygen availability. Hypoxia-induced HIF’s attenuate mitochondrial function through diverse mechanisms, including down-regulation of enzymes in the electron transport chain and suppression of biogenesis of mitochondria. Signalling pathways involving HIF’s and many products of oncogenes and tumour suppressor genes interact to balance the energy needs of dividing cells with the requirement for bio-synthetic intermediates. Activation of lipid biosynthesis and other pathways with biosynthetic significance, such as the pentose phosphate pathway, is another metabolic consequence of hypoxia and HIF up-regulation. Reactive oxygen species ROS produced by the mitochondria stabilise HIF-1, influence redox homeostasis, and provide protective antioxidants to the cancer cells.


Clostridium difficile studies can be done in a Whitley Workstation

Hallmarks of Cancer: Sustaining Growth and Resisting Cell Death

In part four of our mini-series describing “Hypoxia and the Hallmarks of Cancer”, we look more closely at how researchers are using the Hypoxystation to delineate the Hallmarks Sustaining Growth and Resisting Cell Death.






Hallmarks of Cancer

Resisting Cell Death

The ability of cells to resist cell death under hypoxic conditions is central to the progression of cancer and the acquisition of resistance to chemotherapy so frequently encountered in tumors. Hypoxia in the tumor microenvironment exerts selective pressure favoring cells that have lost the functionality of apoptosis genes and can expand uncontrollably.  Hypoxia also contributes to survival by inducing autophagy, in a pathway involving HIF-1, beclin, BNIP3 and BNIP3L, in which cellular autophagy acts to recycle cellular organelles, satisfy metabolic demand and improve hypoxic tolerance.  HIF-1 mediates cell-cycle retardation and arrest, causing hypoxic tumor cells to become resistant to radiotherapies. NF-κB, through its effects on myriad transcription factors, for example through inhibition of cell death signalling, is activated by hypoxia and reactive oxygen species, and also promotes cell survival.

Sustaining Growth

Cancer is essentially based on the cells’ inability to “stop” when suppressors signal an end to growth, and the compunction to “go” despite a lack of bonafide growth signals. Hypoxia in the context of cancer, in precipitating genomic instability and mutation, results in numerous inactive tumor suppressor genes and activated growth factor genes, such that the combination of constitutive proliferative signaling and mutated cancer genes leads to sustained growth. HIF and NF-κB regulated pathways involving Notch, mTOR, WNT11, CAIX, and IGF-1, among many others, contribute to sustained growth in cancer as regulation of proliferation derails. Induced by hypoxia-regulated proteins, anabolic pathways for nucleotide and lipid synthesis are ramped up and enable the rapid proliferation typical of cancer.







Hypoxia and the Hallmarks of Cancer: Angiogenesis and Metastasis

The following was provided by HypOxygen, our distributor of Hypoxic Workstations in the US – Hanahan and Weinberg’s “Hallmarks of Cancer” are at the root of the multi-step progression of cancer, and they are all influenced by hypoxia in the tumor microenvironment. In this mini-review series, HypOxygen has been taking a closer look at the way Hypoxystation users worldwide are delineating the effects of hypoxia on the Hallmarks of Cancer: so far, we’ve showcased Avoiding Immune Destruction and Tumour Promoting Inflammation and Genome Instability and Mutation and Enabling Replicative Immortality.

In the Hypoxystation, researchers working with cells in culture can mimic the physiological conditions that produce those characteristic Hallmarks. The Hypoxystation enables glove-less access to cultivate and manipulate cells under physiological conditions, in a HEPA-clean environment. Oxygen levels in the Hypoxystation can be reliably and accurately adjusted to below 1%, reflecting the high metabolism, low perfusion tumor microenvironment.




Hallmarks Of Cancer
1. Inducing Angiogenesis

Angiogenesis and tumor-associated neo-vascularization are central to the progression of cancer, and hypoxia in the fast-growing, poorly perfused tumor setting is one of the main factors driving the formation of new vessels. Hypoxia in the tumor activates the hypoxia stress response, which is mediated at the cellular level by HIF, VEGF and many other cytokines, growth factors and guidance molecules. As a consequence, endothelial cells and pericytes proliferate and form new blood vessels, which are, however, disorderly and leaky, in turn exacerbating hypoxia in the tumor. Cancer treatment strategies striving to normalize tumor vessels for the purpose of improved drug delivery and alleviation of hypoxia in the tumor are showing great promise.


2. Activating Invasion and Metastasis

As with the other Hallmarks of Cancer, metastasis and cancer progression are correlated with low oxygen levels in the tumor. HIF’s activate the expression of more than 1000 genes, numerous of which play a role in inducing genes involved in the EMT, through direct interactions with HRE’s at promotor sites and other mechanisms such as epigenetic alterations, like methylation/demethylation. Hypoxia promotes migration and invasion by facilitating the endothelial-mesenchymal transition, altering cell-cell contacts, and reducing adhesion to the extra-cellular matrix. Cancer cells and neighboring cells such as fibroblasts are all influenced by hypoxia, and all contribute to the restructuring of the tumor microenvironment. The effects of the Hallmarks of Cancer continually perturb and promote each other, as when hypoxia-driven metabolic reprogramming causes acidification of the extracellular microenvironment through increased production and secretion of lactate, in turn augmenting ECM remodeling and immune evasion. Similarly, formation of novel blood vessels enables extravasation and migration of cancer cells to form new tumors.



The Hallmarks of Cancer

The Hallmarks of Cancer are a specific set of characteristics that are inherent to cancer. The Hallmarks were published by Hanahan and Weinberg in 2000 (updated in 2011) and have become extremely recognisable in the cancer research community both as a scientific concept and as a strong, visual image.

The Hallmarks of Cancer have been an area of study for several years and a key focus of research into causes and progression of cancer. One such study by a lab in Sweden using the H35 Hypoxystation, entitled “Therapeutic targeting of hypoxia and hypoxia-inducible factors in cancer” by Wigerup, Pahlman and Bexell links cancer characteristics with hypoxia as an underlying cause.  This review of hypoxia-driven cancer characteristics and tumour progression makes a crucial connection between hypoxia and the “Hallmarks of Cancer”, a set of specific characteristics that are inherent to cancer. There are many more publications showing that hypoxia is intimately involved in every aspect of the disease complex cancer.

The image below summarises the 9 Hallmarks of Cancer. The Hypoxystation in the middle of the graphic symbolises how the low oxygen environment re-creates the atmosphere where cancer cells are required to act in a physiological manner. The dial around the Hypoxystation indicates the different levels of oxygen required for specific types of cancer work. Ultimately, the graphic shows how the Hypoxystation facilitates a level of oxygen that cannot be achieved reliably in an incubator, and which is necessary to effectively research cancer therapies.


Graphic provided by HypOxygen