Department of Molecular Nutrition, CSIR-Central Food Technological Research Institute (CFTRI), Mysore, 570 020, Karnataka, India.
Department of Biochemistry, CSIR-Central Food Technological Research Institute (CFTRI), Mysore, 570 020, Karnataka, India.
Mol Cell Biochem. 2017 Dec;436(1-2):1-12. doi: 10.1007/s11010-017-3071-4. Epub 2017 May 26.
Although β-carotene is known for its anti-carcinogenic and antioxidant properties, a few recent epidemiological and experimental evidence show that at higher concentration it acts as pro-oxidant and induces cancer. Since the global burden of breast cancer exceeds all other types of cancer, and its incidence rates is also in increasing trend, the present study attempted to evaluate the anti-cancer molecular mechanism of β-carotene (at 1 µM concentration) isolated from Spinacia oleracea in human breast cancer (MCF-7) cells. The carotenoid was purified by open column chromatography and identified by LC-MS. The anti-proliferative effect of β-carotene at different concentrations was evaluated by WST-1 assay and the changes in cell morphology were examined by microscopic observation. The induction of apoptosis by β-carotene was observed by DAPI staining and colorimetric caspase-3 assay. The expression of cell survival, apoptotic, and antioxidant marker proteins was measured by western blot analysis. Purified β-carotene inhibited the viability of MCF-7 cells in a dose-dependent manner, which was well correlated with changes in cell morphology. Increased apoptotic cells were observed in β-carotene (1 µM)-treated cells. This apoptosis induction was associated with increased caspase-3 activity. The protein expression studies showed that β-carotene at 1 µM concentration effectively decreases the expression of the anti-apoptotic protein, Bcl-2 and PARP, and survival protein, NF-kB. It also inhibited the activation of intracellular growth signaling proteins, Akt and ERK1/2. The inhibition of Akt activation by β-carotene results in decreased phosphorylation of Bad. Further, it down-regulated antioxidant enzyme, SOD-2, and its transactivation factor (Nrf-2), and endoplasmic reticulum (ER) stress marker, XBP-1, at protein levels. These findings exhibit the key role of β-carotene even at a low physiological concentration in MCF-7 cells which further explains its predominant anti-cancer activity.
尽管 β-胡萝卜素以其抗癌和抗氧化特性而闻名，但最近的一些流行病学和实验证据表明，在较高浓度下，它会表现出促氧化剂的作用，并诱发癌症。由于乳腺癌的全球负担超过其他所有类型的癌症，而且其发病率也呈上升趋势，因此本研究试图评估从菠菜中分离出的 β-胡萝卜素（浓度为 1 μM）对人乳腺癌（MCF-7）细胞的抗癌分子机制。类胡萝卜素通过开放柱层析法进行纯化，并通过 LC-MS 进行鉴定。通过 WST-1 测定法评估 β-胡萝卜素在不同浓度下的抗增殖作用，并通过显微镜观察检查细胞形态的变化。通过 DAPI 染色和比色 caspase-3 测定观察 β-胡萝卜素诱导的细胞凋亡。通过 Western blot 分析测量细胞存活、凋亡和抗氧化标志物蛋白的表达。纯化的 β-胡萝卜素以剂量依赖性方式抑制 MCF-7 细胞的活力，这与细胞形态的变化密切相关。在 β-胡萝卜素（1 μM）处理的细胞中观察到凋亡细胞增加。这种细胞凋亡诱导与 caspase-3 活性的增加有关。蛋白表达研究表明，在 1 μM 浓度下，β-胡萝卜素有效降低了抗凋亡蛋白 Bcl-2 和 PARP 以及生存蛋白 NF-κB 的表达。它还抑制了细胞内生长信号蛋白 Akt 和 ERK1/2 的激活。β-胡萝卜素对 Akt 激活的抑制导致 Bad 的磷酸化减少。此外，它下调了抗氧化酶 SOD-2 及其转录激活因子（Nrf-2）以及内质网（ER）应激标志物 XBP-1 的蛋白水平。这些发现表明，即使在 MCF-7 细胞中生理浓度较低的情况下，β-胡萝卜素也发挥着关键作用，进一步解释了其主要的抗癌活性。
