Protocol won't work for all forms of cancer
Posted 08-29-2010 at 06:50 AM by jfh
The role of intracellular pH (pHi) regulation in hematopoiesis is an area of research that has received little attention. Yet the concern for maintaining pH as an important parameter in all in vitro work is well known. By keeping the extracellular pH (pHe) constant, we assume that the cells will be able to regulate their own pHi. This is indeed the case because cells are equipped with several different exchangers to help regulate pHi and to counteract acidification either by efflux of H+ ions or influx of HCO3 ions. The Na+-dependent and -independent Cl/HCO3 exchangers and an adenosine triphosphate-dependent H+ pump are important if the cell becomes too acidic or too alkaline. Thus, whereas the Na+-linked Cl/HCO3 antiporter exchanges Na+ and HCO3 ions for Cl ions, thereby causing a increase in cytosolic pHi, the Na+-independent Cl/HCO3 exchanger reduces pHi in cells with an alkali overload. However, the primary regulator of pHi is the Na+/H+ exchanger (NHE) of which there are 6 known isoforms. [This becomes important when using the sodium bicarbonate protocol. A lot more information, about these exchangers, can be found at the web link. Of course, increasing and lowering the H, by the exchangers, increase and lower the pH.]
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All the growth factors [interleukin-2,3 etc. from T cells] tested have been shown to increase pHi with an associated activation of cell stimulation and proliferation. For example, using the interleukin-3 (IL-3)-dependent stem-cell line, FDCP-mix, Whetton et al demonstrated that IL-3 activates the NHE and that theresultant intracellular alkalinization was a signal for proliferationof these cells. � Removal of growth factors such as IL-2 from IL-2-dependent cytotoxic T cells resulted in a decrease in pHi and the onset of apoptosis.
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In contrast to activation of the NHE1 and the concomitant increase in pHi by various stimuli, a decrease in pHi can result in apoptosis of the cell. Several reports using different leukemic cell lines demonstrated that if the Na+/H+ exchanger was inhibited by amiloride analogs, acidification ofthe cells occurred with a concomitant induction of apoptosis. We hypothesized that cells maintaining a high rate of proliferation should exhibit a sustained increase in pHi relative to normal cells as a result of activation of the NHE1. [So, an internal alkaline environment makes the leukemic cells multiply faster.] Here we show that leukemic cell lines and primary patient leukemic samples exhibit a greater pHi than normal cells, that pHi is correlated with cell-cycle status, and that inhibition of NHE1 in patient leukemic cells results in a decrease in pHi and an increase in apoptosis. [This means that our SB protocol won't work with leukemia. Neither will cesium, since cesium makes the intracellular environment more alkaline. A chloride channel blocker might work. That is another story, which I'm not prepared to follow yet.]
Pasted from <https://bloodjournal.hematologylibrar...full/95/4/1427>
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All the growth factors [interleukin-2,3 etc. from T cells] tested have been shown to increase pHi with an associated activation of cell stimulation and proliferation. For example, using the interleukin-3 (IL-3)-dependent stem-cell line, FDCP-mix, Whetton et al demonstrated that IL-3 activates the NHE and that theresultant intracellular alkalinization was a signal for proliferationof these cells. � Removal of growth factors such as IL-2 from IL-2-dependent cytotoxic T cells resulted in a decrease in pHi and the onset of apoptosis.
�
In contrast to activation of the NHE1 and the concomitant increase in pHi by various stimuli, a decrease in pHi can result in apoptosis of the cell. Several reports using different leukemic cell lines demonstrated that if the Na+/H+ exchanger was inhibited by amiloride analogs, acidification ofthe cells occurred with a concomitant induction of apoptosis. We hypothesized that cells maintaining a high rate of proliferation should exhibit a sustained increase in pHi relative to normal cells as a result of activation of the NHE1. [So, an internal alkaline environment makes the leukemic cells multiply faster.] Here we show that leukemic cell lines and primary patient leukemic samples exhibit a greater pHi than normal cells, that pHi is correlated with cell-cycle status, and that inhibition of NHE1 in patient leukemic cells results in a decrease in pHi and an increase in apoptosis. [This means that our SB protocol won't work with leukemia. Neither will cesium, since cesium makes the intracellular environment more alkaline. A chloride channel blocker might work. That is another story, which I'm not prepared to follow yet.]
Pasted from <https://bloodjournal.hematologylibrar...full/95/4/1427>
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