I found that mRNA levels of hemoglobin genes are downregulated very often in cancers (attached figure). I have checked Google and Wikigene, but I couldn't find any review article giving it an explanation. Does anyone know what the downregulation means?
Seems Hb is expresseed in several tissues other than blood cells. I cancer cells, both increase (Ref1) and decreased expression (Ref2) has been described. Oxygen supply may frequently be critical in tumors with their high cell proiferation rate, high metabolism and pathologically (that means less than perfect) neovascularization. So it seems plausible that everything that facilitates oxygen uptake in the tumor helps. Gorr et al. on the other hand suggest to “consider that cancer-expressed globins might function in ways not directly linked to the binding and transport of oxygen”
1. Gorr TA et al,: . Old proteins - new locations: myoglobin, haemoglobin, neuroglobin and cytoglobin in solid tumours and cancer cells. Acta Physiol (Oxf). 2011 Jul;202(3):563-81
2: Chang SC et al: Haemoglobin in normal and neoplastic canine mammary glands. Vet Comp Oncol. 2010 Dec;8(4):302-9
Intriguing question - and not a simpe search. Any combination of cancer AND hemoglobin in pubmed gives abundant hits on cancer patients with low Hb. Refining the search seems not as easy.
I do hope this question will get some meaningful answers - including references -not necessarily areviews, seems there aren't any
@Rohan: is this expression of tumor sample versus normal tissue (i.e. did you isolate RNA from the tissue directly from surgery) or from primary cell culture (tumor cells versus normal primary cells? The tumor tissue possibly was somewhat hypocic, the primary cell culture should have had enough oxygen?
@Rohan: Two positive/negative samples might not have statistical significance. I am not familiar with the drugs used in breast cancer, so I am not sure if those medications can cause anaemia. Currently, I think that tumor hypoxia might be the reason. Because oxygen supply is lower in the microenvironment, tumor cells have fewer intend to express genes such as HBB for oxygen delivery.
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