Hypoxia Modulates the Localization of Carbonic Anhydrase IX in Cancer Cells

• Published in: Indian journal of clinical biochemistry Vol. 33; no. S1; p. S85
• Main Authors: Garg, Surbhi, Mudassir, Madeeha, Bhagat, Mohita, Chattopadhyay, Parthaprasad
• Format: Journal Article
• Language: English
• Published: Springer 24-05-2022
• Subjects: Analysis; Cancer; Cancer cells; Development and progression
• ISSN: 0970-1915

Increased metabolic activity in tumor cells lead to alkaline intracellular pH and acidic extracellular pH. CA-IX catalyze the reversible hydration of carbon dioxide. CA-IX being transmembrane in location plays significant role in tumor progression by maintaining this pH gradient in tumor microenvironment. CA-IX surface expression and internalization in migratory cancer cells is still unknown. Siha and Hela cells were maintained in normoxia (20% O2) and hypoxia (0.2% O2) for 7 days. Transwell migration assay was performed. Cells were exposed to primary anti CA-IX antibody for 5 min. One set of cells were fixed immediately as control and another set of cells were fixed after further incubation in 37[degrees]C for 1 h. Analysis was done using confocal microscopy and image J software. We have found increased immunofluorescence (suggesting the presence of CA-IX) in hypoxic cells as compared to normoxic cells after signal amplification with tyramide reagent. CA-IX florescence intensity was enhanced in migratory cells as compared to non-migratory cells. Further incubated hypoxic cells showed more cytoplasmic signal and less membranous signal as it is opposite in fixed control cells treated with ice cold sodium azide to block membrane transport. Interestingly we found that CA-IX localization to cytoplasm was maximum in case of hypoxic migratory cells. Insignificant difference in florescence intensity was seen among migratory and non-migratory normoxic cells. Hypoxia mediated internalization of membrane bound CA-IX into cytoplasm of cancer cells can be correlated with migration of tumor cells. KEY WORDS: Carbonic anhydrase IX, Hela and Siha cells, Hypoxia