Taylor I W, Hodson P J
J Cell Physiol. 1984 Dec;121(3):517-25. doi: 10.1002/jcp.1041210310.
Purified populations of quiescent human tumour cells were isolated from plateau phase cultures of PMC-22 cells by centrifugal elutriation. Dilution into fresh medium resulted in these quiescent cells entering S phase exponentially with a t1/2 of 12 hr, after a 18-20-hr lag period during which cellular RNA content increased. Subsequent studies showed that recruitment of quiescent cells into the cell cycle could be regulated by extracellular pH. When exponentially growing PMC-22 cells were exposed to acidic extracellular pH levels, three growth patterns were observed: 1) Normal growth between pH 7.2 to pH 6.8; 2) A reduction in growth rate associated with accumulation of cells with a G1 DNA content between pH 6.7 and 6.4 (this was also shown to occur in a number of other tumour cell lines); 3) Non-cell-cycle-phase-specific arrest of growth at pH levels less than 6.3. Further studies with purified quiescent cell populations showed the possible existence of a pH-dependent restriction point in the G1 phase of these tumour cells. The implications of these observations to tumour biology are discussed.
通过离心淘析从PMC - 22细胞的平台期培养物中分离出纯化的静止人类肿瘤细胞群体。将其稀释到新鲜培养基中后，这些静止细胞在细胞RNA含量增加的18 - 20小时延迟期后，以12小时的半衰期呈指数进入S期。后续研究表明，静止细胞进入细胞周期可受细胞外pH值调节。当指数生长的PMC - 22细胞暴露于酸性细胞外pH水平时，观察到三种生长模式：1）pH 7.2至pH 6.8之间正常生长；2）pH 6.7至pH 6.4之间生长速率降低，伴有具有G1 DNA含量的细胞积累（这在许多其他肿瘤细胞系中也有发生）；3）在pH值低于6.3时非细胞周期阶段特异性生长停滞。对纯化的静止细胞群体的进一步研究表明，这些肿瘤细胞的G1期可能存在pH依赖性限制点。讨论了这些观察结果对肿瘤生物学的意义。
