Flux analysis shows that hypoxia-inducible-factor-1-alpha minimally affects intracellular metabolism in tumor spheroids
Flux analysis shows that hypoxia-inducible-factor-1-alpha minimally affects intracellular metabolism in tumor spheroids
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DOI：
10.1002/bit.21205
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发表时间：
2007-04-15
影响因子：
3.8
通讯作者：
Forbes, Neil S.
中科院分区：
文献类型：
--
作者：
Kim, Byoung-jin;Forbes, Neil S.
肿瘤中的异质性代谢微环境影响局部细胞生长、存活和总体治疗效果。低氧诱导因子-1 α（HIF 1-α）是一种转录因子，通过上调细胞存活和代谢基因来响应低氧环境。迄今为止，HIF-1 α在三维组织中的代谢作用尚未研究。初步实验表明，HIF-1 α的作用依赖于葡萄糖的可用性。基于这一观察结果，我们假设HIF-1 α不会影响球体中心的细胞存活和代谢，其中氧和葡萄糖浓度较低，类似于肿瘤中发现的缺氧区域。为了验证这一假设，我们使用荧光显微镜和肿瘤圆柱体模型来量化三维组织中的细胞活力。同位素标记和代谢通量分析也被用来量化野生型和HIF-1 α-空球状体的细胞内代谢。正如假设的那样，野生型和HIF-1 α-null组织之间的细胞存活和细胞内代谢没有差异。此外，发现含有较少静止细胞且较少营养限制的小球状体通过生物合成戊糖和丙酮酸羧化酶途径具有增加的碳通量。这些结果表明营养梯度影响球体中的细胞生长和代谢，并表明在开发基于HIF-1 α的疗法时应考虑代谢微环境。
Heterogenous metabolic microenvironments in tumours affect local cell growth, survival, and overall therapeutic efficacy. Hypoxia-inducible-factor-1 alpha (HIF1-alpha) is a transcription factor that responds to low-oxygen environments by upregulating genes for cell survival and metabolism. To date, the metabolic effects of HIF-1 alpha in three-dimensional tissue have not been investigated. Preliminary experiments have shown that effects of HIF-1 alpha are dependent on glucose availability. Based on this observation, we hypothesized that HIF-1 alpha would not affect cell survival and metabolism in the center of spheroids, where the concentrations of oxygen and glucose are low, similar to hypoxic regions found in tumors. To test this hypothesis we used fluorescence microscopy and the tumor cylindroid model to quantify cellular viability in three-dimensional tissue. Isotope labeling and metabolic flux analysis were also used to quantify the intracellular metabolism of wild-type and HIF-1 alpha-null spheroids. As hypothesized, cell survival and intracellular metabolism were not different between wild-type and HIF-1 alpha-null tissues. In addition, small spheroids, which contain less quiescent cells and are less nutritionally limited, were found to have increased carbon flux through the biosynthetic pentose and pyruvate carboxylase pathways. These results show nutrient gradients affect cell growth and metabolism in spheriods and suggest that metabolic microenvironment should be taken into account when developing HIF-1 alpha-based therapies.