Grape Seed Proanthocyanidins Inhibit the Growth of Human Non-Small Cell Lung Cancer Xenografts by Targeting Insulin-Like Growth Factor Binding Protein-3, Tumor Cell Proliferation, and Angiogenic Factors
Abstract Purpose: Lung cancer is a leading cause of cancer-related deaths worldwide. Here, we assessed the chemotherapeutic effect of grape seed proanthocyanidins (GSPs) on human non-small cell lung cancer (NSCLC) cells in vitro and in vivo using a tumor xenograft model.
Experimental Design: The effects of GSPs on human NSCLC cell lines in terms of cellular proliferation were determined. The chemotherapeutic effects of a GSP- supplemented AIN76A control diet fed to nude mice bearing tumor xenografts (A549 and H1299) were evaluated in terms of biomarkers of cell proliferation and angiogenesis and on insulin-like growth factor binding protein-3 using immunohistochemical detection, ELISA, and Western blotting.
Results:In vitro treatment of NSCLC cells with GSPs resulted in inhibition of cellular proliferation. Administration of GSPs (0.1%, 0.2%, and 0.5%, w/w) as a supplement of an AIN76A control diet resulted in a dose-dependent inhibition of the growth of NSCLC (A549 and H1299) tumor xenografts in athymic nude mice (25-76%; P < 0.05-0.001). The growth-inhibitory effect of GSPs on the NSCLC xenograft tumors was associated with the enhancement of the levels of insulin-like growth factor binding protein-3 in the tumor microenvironment and plasma and antiproliferative, antiangiogenic, and proapoptotic effects.
Conclusions:This preclinical study reveals for the first time that dietary GSPs have the ability to inhibit the growth of human NSCLC tumor xenografts grown in vivo in athymic nude mice. More studies are needed to develop GSPs as a pharmacologically safe agent for the prevention of lung cancer in humans.
SOURCE:doi: 10.1158/1078-0432.CCR-08-1901 Clinical Cancer Research February 2009 15; 821 LINK TO FULL ARTICLE
Induction of Apoptosis in Human Leukemia Cells by Grape Seed Extract Occurs via Activation of c-Jun NH2-Terminal Kinase
Abstract Purpose: To characterize the functional role of c-Jun NH2-terminal kinase (JNK) and other apoptotic pathways in grape seed extract (GSE)-induced apoptosis in human leukemia cells by using pharmacologic and genetic approaches.
Experimental Design: Jurkat cells were treated with various concentrations of GSE for 12 and 24 h or with 50 μg/mL GSE for various time intervals, after which apoptosis, caspase activation, and cell signaling pathways were evaluated. Parallel studies were done in U937 and HL-60 human leukemia cells.
Results: Exposure of Jurkat cells to GSE resulted in dose- and time-dependent increase in apoptosis and caspase activation, events associated with the pronounced increase in Cip1/p21 protein level. Furthermore, treatment of Jurkat cells with GSE resulted in marked increase in levels of phospho-JNK. Conversely, interruption of the JNK pathway by pharmacologic inhibitor (e.g., SP600125) or genetic (e.g., small interfering RNA) approaches displayed significant protection against GSE-mediated lethality in Jurkat cells.
Conclusions:The result of the present study showed that GSE induces apoptosis in Jurkat cells through a process that involves sustained JNK activation and Cip1/p21 up-regulation, culminating in caspase activation.
Grape Seed Extract Inhibits In vitro and In vivo Growth of Human Colorectal Carcinoma Cells Manjinder Kaur,1Rana P. Singh,1Mallikarjuna Gu,1Rajesh Agarwal,1,2 and Chapla Agarwal1,2
Abstract Purpose: Accumulating evidences suggest the beneficial effects of fruit-and-vegetable consumptioninlowering the riskof various cancers, including colorectal cancer.Herein,we investigated the in vitro and in vivo anticancer effects and associated mechanisms of grape seed extract (GSE), a rich source of proanthocyanidins, against colorectal cancer. Experimental Design: Effects of GSE were examined on human colorectal cancer HT29 and LoVo cells in culture for proliferation, cell cycle progression, and apoptosis. The in vivo effect of oral GSE was examined on HT29 tumor xenograft growth in athymic nude mice. Xenografts were analyzed by immunohistochemistry for proliferation and apoptosis. The molecular changes associated with the biological effects of GSE were analyzed by Western blot analysis.
Results: GSE (25-100 Ag/mL) causes a significant dose- and time-dependent inhibition of cell growth with concomitant increase in cell death. GSE inducedG1phase cell cycle arrest alongwith a marked increase in Cip1/p21protein level and a decrease in G1phase ^ associated cyclins and cyclin-dependent kinases.GSE-induced cell deathwas apoptotic and accompanied bycaspase-3 activation. GSE feeding to mice at 200 mg/kg dose showed time-dependent inhibition of tumor growth without any toxicity and accounted for 44% decrease in tumor volume per mouse after 8weeks of treatment. GSE inhibited cell proliferation but increased apoptotic cell death in tumors.GSE-treated tumors also showed enhanced Cip1/p21protein levels and poly(ADP-ribose) polymerase cleavage.
Conclusions: In summary, our results show that GSE inhibits cell growth and induces cell cycle arrest and apoptosis in human colorectal cancer cells and modulates cell cycle regulators with a strong effect for Cip1/p21 up-regulation. Usually, p53 plays a regulatory role in Cip1/p21 induction; however, in our studies, GSE up-regulates Cip1/p21 independent of p53 because HT29 cells showing a robust increase in Cip1/p21 harbor nonfunctional p53, although LoVo cells carry wild-type p53. Therefore, it would be of significance to investigate in future studies the p53-independent mechanisms of Cip1/p21 induction by GSE that might have a wide implication in cancer chemoprevention as p53 inactivation is one of the primary events in initiation, growth and progression of many types of cancers, including colorectal cancer. Furthermore, findings in xenograft study translate the anticancer effects and associated mechanisms of GSE observed in cell culture experiments in to an in vivo preclinical colorectal cancer model. However, a dose-dependent in vivo study with GSE is needed in future that would provide additional information regarding the lowest effective as well as highest nontoxic doses of GSE, which would be useful for the translational studies.GSE may be an effective chemopreventive agent against colorectal cancer, and that growth inhibitory and apoptotic effects of GSE against colorectal cancer could be mediated via an up-regulation of Cip1/p21.