I was interested to see this morning's news [1] because it has a bearing on a point I was recently trying to make (unsuccessfully).
It's not uncommon to find someone on a cancer site claim that cancer hates oxygen. 'If only we could get more oxygen to the cancer it would die.' PCa is not at all inconvenienced by a robust supply of oxygenated blood. However, solid tumors are eventually victims of their success & become "hypoxic" (low oxygen) due to a blood supply that has been outgrown.
The response to hypoxia is multifactorial (all related to cell survival), but the hallmark of the response is the building of new blood vessels.
Kaelin was co-author of a 2000 Dana-Farber paper [2]:
"Chronic hypoxia, a hallmark of many tumors, is associated with angiogenesis and tumor progression. Strategies to treat tumors have been developed in which tumor cells are targeted with drugs or gene-therapy vectors specifically activated under hypoxic conditions."
Semenza (2009) [5]:
"In cancer, vascularization is required for tumors to grow beyond microscopic size, a process that involves HIF-1-dependent production of angiogenic growth factors. Daily treatment of prostate cancer xenograft-bearing mice with low-dose anthracycline (doxorubicin or daunorubicin) chemotherapy inhibits HIF-1 DNA-binding activity, HIF-1-dependent expression of angiogenic growth factors, mobilization of circulating angiogenic cells, and tumor vascularization, thereby arresting tumor growth."
Hypoxia-inducible factor-1alpha [HIF1a] causes the generation of vascular endothelial growth factor [VEGF]. From a 2014 Spanish paper:
"Induction of angiogenesis represents one of the major hallmarks of cancer. The growth of new vessels is crucial to provide malignant cells with an adequate supply of oxygen and nutrients. It is generally accepted that vascular endothelial growth factor (VEGF) is a major driver of the angiogenic process in physiological and pathological processes in both embryo and adult. VEGF is often found overexpressed in tumors, as well as its receptors VEGFR1 and VEGFR2. Hence, several different strategies have been designed to target VEGF signal transduction. In the last decades, multiple inhibitors have been therapeutically validated in preclinical models and several clinical trials. Neutralizing monoclonal antibodies against VEGF and small molecule tyrosine kinase inhibitors targeting VEGFRs have been shown to block its angiogenic activity, resulting in tumor vascular regression, anti-tumor effects and improvements in patient survival. However, side effects and lack of efficacy in some instances challenge the potential clinical impact of these therapies. This review examines the role of VEGF signaling in cancer and outlines the current status of anti-angiogenic therapies against VEGF pathway."
In 2002, Kaelin described "How oxygen makes its presence felt" [3].
From 2011 [4]:
"When cells are placed in a low oxygen environment they normally undergo a series of metabolic adaptations including an increase in glucose uptake and glycolysis and a decrease in oxidative phosphorylation. Conversely, the presence of oxygen is associated with a decrease in glycolysis and an increase in oxidative phosphorylation. The coupling of oxidative phosphorylation is known as the Pasteur Effect and is mediated by the HIF transcription factor."
"HIF is a heterodimer consisting of an unstable alpha subunit and a stable beta subunit (also frequently called ARNT) (Kaelin and Ratcliffe 2008). Under low oxygen conditions the HIF alpha subunit is stabilized, dimerizes with a HIF beta subunit, translocates to the nucleus, and transcriptionaly activates a suite of genes that increase glucose uptake, increase glycolysis, and decrease oxidative phosphorylation."
***
HIF1a is responsible not only for triggering angiogenesis, but also for cell survival genes that conribute to treatment resistance. In the presence of adequate oxygen, HIF1a becomes unstable & is eliminated.
Ironically, those who want to restore a good supply of oxygen to hypoxic tumors are on to a good thing. But for men with advanced PCa who are on ADT, the red blood cells that carry oxygen are much reduced. ADT accelerates hypoxia.
For men not on ADT, or on an ADT vacation, restoration of high-normal testosterone will restore normal RBC counts.
Possible strategies for increasing the oxygen supply (a) increase the re-oxygenation rate via exercise & (b) dilate blood vessels via a nitroglycerine patch.
-Patrick
[1] nytimes.com/2019/10/07/heal...
[2] ncbi.nlm.nih.gov/pubmed/239...
[3] genesdev.cshlp.org/content/...