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Rhein, an anthraquinone derivative of rhubarb, inhibits the proliferation of various human cancer cells. In this paper, we focused on studying the effects of rhein on human hepatocelluar carcinoma BEL-7402 cells and further understanding the underlying molecular mechanism in an effort to make the potential development of rhein in the treatment of cancers. Using MTT assay and flow cytometry, we demonstrate a critical role of rhein in the suppression of BEL-7402 cell proliferation in a concentration- and time-dependent manner. The increase of apoptosis rate was observed after incubation of BEL-7402 cells with rhein at 50–200 μM for 48 hours, and the cells exhibit typical apoptotic features including cellular morphological change and chromatin condensation. Moreover, rhein-induced cell cycle S-phase arrest. Additionally, after rhein treatment, expression levels of c-Myc gene were decreased, while those of caspase-3 gene were increased in a dose-dependent manner by using real-time PCR assay. The results demonstrate for the first time that cell cycle S-phase arrest is one of the mechanisms of rhein in inhibition of BEL-7402 cells. Rhein plays its role by inducing cell cycle arrest via downregulation of oncogene c-Myc and apoptosis through the caspase-dependent pathway. It is expected that rhein will be effective and useful as a new agent in hepatocelluar carcinoma treatment in the future.

Corydalis yanhusuo W.T. Wang (YHS) is a traditional Chinese herb widely prescribed for promoting blood circulation, reinforcing vital energy and alleviating pain. Our previous studies showed that an ethanol extract of YHS inhibits metastasis of breast cancer cells in vitro. In the present study, the anti-proliferative effect of the extract was determined by MTT assay and the LDH release was measured with a commercial kit. Intracellular reactive oxygen species (ROS) production and mitochondrial membrane potential (ΔΨm) were monitored by CM- H₂DCF-DA and JC-1 staining, respectively. Cell cycle was analyzed with propidium iodide (PI) staining by flow cytometry and protein expressions were measured by Western blotting. The YHS extract significantly inhibited MCF-7 cell proliferation in a dose-dependent manner. Significant increase of ROS formation and decrease of ΔΨm were observed. Furthermore, it induced MCF-7 cell cycle arrest at the G2/M phases. In addition, the p-cdc-2/cdc-2 protein expression ratio was increased while Rb and p21 protein expressions were decreased.

The YHS extract inhibited MCF-7 proliferation by inducing G2/M cell cycle arrest, which might be mediated by inducing ROS formation, decreasing ΔΨm and regulating cell cycle related protein expressions.

Chemopreventive agents can be identified from botanicals. Recently, there has been strong support for the potential of 6-shogaol, a natural compound from dietary ginger (Zingiber officinale), in cancer chemoprevention. However, whether 6-shogaol inhibits the growth of colorectal tumors in vivo remains unknown, and the underlying anticancer mechanisms have not been well characterized. In this work, we observed that 6-shogaol (15 mg/kg) significantly inhibited colorectal tumor growth in a xenograft mouse model. We show that 6-shogaol inhibited HCT-116 and SW-480 cell proliferation with IC50 of 7.5 and 10 μM, respectively. Growth of HCT-116 cells was arrested at the G2/M phase of the cell cycle, primarily mediated by the up-regulation of p53, the CDK inhibitor p21^waf1/cip1 and GADD45α, and by the down-regulation of cdc2 and cdc25A. Using p53^-/- and p53^+/+ HCT-116 cells, we confirmed that p53/p21 was the main pathway that contributed to the G2/M cell cycle arrest by 6-shogaol. 6-Shogaol induced apoptosis, mainly through the mitochondrial pathway, and the bcl-2 family might act as a key regulator. Our results demonstrated that 6-shogaol induces cancer cell death by inducing G2/M cell cycle arrest and apoptosis. 6-Shogaol could be an active natural product in colon cancer chemoprevention.

5,6-dihydroxy-2,4-dimethoxy-9,10-dihydrophenanthrene (HMP) is an active compound isolated from the rhizome extracts of Dioscorea membranacea Pierre, a Thai medicinal plant. This study aimed to investigate the growth-inhibitory and apoptosis-inducing effects of HMP in human lung cancer A549 cells. The antiproliferative and cytotoxic effects of HMP were analyzed by a Sulforhodamine B assay. Cell division, cell cycle distribution and membrane asymmetry changes were each performed with different fluorescent dyes and then analyzed by flow cytometry. Real-time PCR and immunoblotting were used to detect cell cycle- and apoptosis-related mRNA levels and proteins, respectively. The nuclear morphology of the cells stained with DAPI and DNA fragmentation were detected by fluorescence microscopy and gel electrophoresis, respectively. The results showed that HMP exerted strong antiproliferative and cytotoxic activities in A549 cells with the highest selectivity index. It halted the cell cycle in ${\mathrm{\text{G}}}_2$/M phase via down-regulation of the expression levels of regulatory proteins Cdc25C, Cdk1 and cyclinB1. In addition, HMP induced early apoptotic cells with externalized phosphatidylserine and subsequent apoptotic cells in sub-${\mathrm{\text{G}}}_1$ phase. HMP increased caspase-3 activity and levels of the cleaved (active) form of caspase-3 whose actions were supported by the cleavage of its target PARP, nuclear condensation and DNA apoptotic ladder. Moreover, HMP significantly increased the mRNA and protein levels of proapoptotic Bax as well as promoted subsequent caspase-9 activation and BID cleavage, indicating HMP-induced apoptosis via both intrinsic and extrinsic pathways. These data support, for the first time, the potential role of HMP as a cell-cycle arrest and apoptosis-inducing agent for lung cancer treatment.

Bauhinia championii (Benth.) is one of the commonly used herbs in Taiwan. The stem of this plant has been used to treat epigastria pain and rheumatoid arthritis. However, the antitumor activities of this herb have never been reported. This study aims to investigate the mechanism of anticancer activity of the extracts from B. championii (BC). BC was fractionated with a series of organic solvents, including n-hexane (H), ethyl acetate (EA), 1-butanol (B), and water (W). We first investigated the effects of BC-H, BC-EA, BC-B and BC-W partitioned fraction on cell viability. In HCT 116 colon cancer cell lines, BC-EA showed the highest inhibition of cell viability and changed the morphology of cells. With dose- and time-dependent manners, BC-EA inhibited the proliferation of HCT 116 cells by inducing apoptosis and G₀/G₁ phase arrest of cell cycle. To determine the underlying mechanisms, down-regulated CDK2, Cyclin D, and Cyclin E and up-regulated p16, p21, and p53 may account for the cell cycle arrest, while the apoptotic effect of BC-EA may attribute to increased intracellular Ca${}^{2+}$, loss of mitochondria membrane potential ($\mathrm{\Delta }{\mathrm{\Psi }}_m$), increase of Bax, Bak, puma, and AIF, and decrease of Bcl-2. Furthermore, the inactivation of Ras signaling pathway by BC-EA also contributed to its apoptotic effect on HCT 116. Our study demonstrates that BC-EA not only inhibits cell growth but also induces apoptosis through inhibiting Ras signal pathway and increasing p53 expression levels. We suggest that BC-EA may be a new dietary supplement and a useful tool to search for therapeutic candidates against colon cancer.

The molecular mechanism underlying the anticancer effects of Anemarrhena asphodeloides (A. asphodeloides) on colon cancer is unknown. This is the first study evaluating the anticancer effect of A. asphodeloides extract (AA-Ex) in serum-starved colorectal cancer cells. Changes in cell proliferation and morphology in serum-starved MC38 and HCT116 colorectal cancer cells were investigated using MTS assay. Cell cycle and apoptosis were investigated using flow cytometry, and cell cycle regulator expression was determined using qRT-PCR. Apoptosis regulator protein levels and mitogen-activated protein kinase (MAPK) phosphorylation were assessed using western blotting. AA-Ex sensitively suppressed proliferation of serum-starved colorectal cancer cells, with MC38 and HCT116 cells showing greater changes in proliferation after treatment with AA-Ex under serum starvation than HaCaT and RAW 264.7 cells. AA-Ex inhibited cell cycle progression in serum-starved MC38 and HCT116 cells and increased the expression of cell cycle inhibitors (p53, p21, and p27). Furthermore, AA-Ex induced apoptosis in serum-starved MC38 and HCT116 cells. Consistently, AA-Ex suppressed the expression of the anti-apoptotic molecule Bcl-2 and upregulated pro-apoptotic molecules (cytochrome c, cleaved caspase-9, cleaved caspase-3, and cleaved-PARP) in serum-starved cells. AA-Ex treatment under serum starvation decreased AKT and ERK1/2 phosphorylation in the cell survival signaling pathway but increased p38 and JNK phosphorylation. Furthermore, AA-Ex treatment with serum starvation increased the levels of the transcription factors of the p38 and JNK pathway. Serum starvation sensitizes colorectal cancer cells to the anticancer effect of A. asphodeloidesvia p38/JNK-induced cell cycle arrest and apoptosis. Hence, AA-Ex possesses therapeutic potential for colon cancer treatment.

Colorectal cancer (CRC) is the second most common cause of cancer death in the world, and metastatic CRC is a major cause of cancer death. Gallotannin (GT), a polyphenolic compound, has shown various biological effects such as anti-oxidant, anti-inflammatory, antimicrobial, and antitumor effects. However, the effects of GT on metastatic CRC cells are not completely understood. This study aimed to investigate the anti-metastatic effect of GT and the underlying mechanisms on metastatic CRC cells. Oral administration of GT suppressed the lung metastasis of metastatic CRC cells in the experimental mouse model. GT decreased the viability of metastatic CRC cell lines, including CT26, HCT116, and SW620, by inducing apoptosis through the activation of extrinsic and intrinsic pathways, cell cycle arrest through inactivation of CDK2/cyclin A complex, and autophagic cell death through up-regulation of LC3B and p62 levels. GT regulated PI3K/AKT/mTOR and AMPK signaling pathways, which are critical for the development and maintenance of cancer. Additionally, non-cytotoxic concentrations of GT can suppress migration and invasion of CRC cells by inhibiting the expression and activity of matrix metalloproteinase (MMP)-2 and MMP-9 and epithelial-mesenchymal transition by downregulating the expression of mesenchymal markers including snail, twist, and vimentin. In conclusion, GT prevented colorectal lung metastasis by reducing survival and inhibiting the metastatic phenotypes of CRC cells.

Prostate cancer (PC) is the second leading cause of cancer-related death among men. Treatment of PC becomes difficult after progression because PC that used to be androgen-dependent becomes androgen-independent prostate cancer (AIPC). Veratramine, an alkaloid extracted from the root of the Veratrum genus, has recently been reported to have anticancer effects that work against various cancers; however, its anticancer effects and the underlying mechanism of action in PC remain unknown. We investigated the anticancer effects of veratramine on AIPC using PC3 and DU145 cell lines, as well as a xenograft mouse model. The antitumor effects of veratramine were evaluated using the CCK-8, anchorage-independent colony formation, trans-well, wound healing assays, and flow cytometry in AIPC cell lines. Microarray and proteomics analyses were performed to investigate the differentially expressed genes and proteins induced by veratramine in AIPC cells. A xenograft mouse model was used to confirm the therapeutic response and in vivo efficacy of veratramine. Veratramine dose dependently reduced the proliferation of cancer cells both in vitro and in vivo. Moreover, veratramine treatment effectively suppressed the migration and invasion of PC cells. The immunoblot analysis revealed that veratramine significantly downregulated Cdk4/6 and cyclin D1 via the ATM/ATR and Akt pathways, both of which induce a DNA damage response that eventually leads to G1 phase arrest. In this study, we discovered that veratramine exerted antitumor effects on AIPC cells. We demonstrated that veratramine significantly inhibited the proliferation of cancer cells via G0/G1 phase arrest induced by the ATM/ATR and Akt pathways. These results suggest that veratramine is a promising natural therapeutic agent for AIPC.

Cancer dormancy emerges when tumor cells cease to proliferate but remain alive in a quiescent state. Recent evidence suggests that cancer cells can stay dormant in a patient’s body for years before returning to a proliferative state, leading to cancer relapse. The lack of a system to efficiently identify and study dormant cancer cells is currently limiting further diagnostic and treatment developments to prevent cancer relapse. Herein, we present a novel encapsulation platform to identify and study dormancy-capable cancer cells in a quiescent state by inhibiting proliferation through physical confinement. The platform involves the encapsulation of cells within a stiff silica-PEG hydrogel produced by a sol–gel technique. Cells are immobilized in a nondegradable microenvironment where proliferation and movement are inhibited due to physical confinement of the gel. The platform was tested using non-cancerous cell lines HFF, HUVEC, Jurkat, MEF, and MCF-10A, and cancer cell lines LnCAP, MCF-7, MCF10DCIS.com, MDA-MB-468, and OVCAR-5. Viability and metabolic activity measurements showed that MCF-7, LnCAP, and MCF10DCIS.COM cells remained metabolically active for up to 3 weeks while non-cancerous lines and the rest of the cancer cell lines did not survive after a few days. Ki-67 immunofluorescent staining confirmed that surviving MCF-7 cells underwent cell cycle arrest as early as 48 hours after encapsulation. Furthermore, following extraction and recovery, these cells resumed proliferation, indicating that the induced cell cycle arrest was reversible. These results conclude that physically inhibiting proliferation via the silica-PEG hydrogel system can be used to identify cells that can enter a quiescent state, setting the groundwork for this platform to be explored as a cancer cell dormancy model.

Boolean modeling has been successfully applied to the budding yeast cell cycle to demonstrate that both its structure and its timing are robustly designed. However, from these studies few conclusions can be drawn how robust the cell cycle arrest upon osmotic stress and pheromone exposure might be. We therefore implement a compact Boolean model of the S. cerevisiae cell cycle including its interfaces with the High Osmolarity Glycerol (HOG) and the pheromone pathways. We show that all initial states of our model robustly converge to a cyclic attractor in the absence of stress inputs whereas pheromone exposure and osmotic stress lead to convergence to singleton states which correspond to G1 and G2 arrest in silico. A comparison with random Boolean networks reveals, that cell cycle arrest under osmotic stress is a highly robust property of the yeast cell cycle. We implemented our model using the novel frontend booleannetGUI to the python software booleannet.