I've noticed in some H&E tissue samples of hetergeneous urothelial carcinoma & squamous cell carcinoma of the lung that some tumour cells exhibit clear cell change - why does this change occur?

Clear cell change seems to be prevailent in high grade tumours, especially those that exhibit necrosis. The clear cells display high levels of glycogen, confirmed by PAS staining. Glycogenesis-related genes appear to be up-regulated by hypoxia suggesting that glycogen accumulation under hypoxic conditions is an important step in metabolism, whereby cells utilize glycogen as an alternative energy source to support tumour survival under conditions of energy stress.

I know that CA-IX is considered to be one of the best cellular biomarkers of hypoxia and is highly expressed in clear cell renal carcinoma ccRCC but not in healthy renal tissue.

So I was wondering..can clear cell change itself be a potential marker of hypoixa?