Pei-Ni Chen

Cyanidin 3-Glucoside and Peonidin 3-Glucoside Inhibit Tumor Cell Growth and Induce Apoptosis In Vitro and Suppress Tumor Growth In Vivo

Abstract: Dietary polyphenols, including anthocyanins, are suggested to be involved in the protective effects of fruits and vegetables against cancer. However, anticancer effects of peonidin 3-glucoside have not been clearly demonstrated, with only limited studies being available concerning the inhibitory effect of cyanidin 3-glucoside for tumor cell growth. Therefore, in this study, we have isolated and identified the two bioactive compounds, peonidin 3-glucoside and cyanidin 3-glucoside, from Oryza sativa L. indica, to treat various cancer cells. The results showed that, among analyzed cell lines, HS578T was the most sensitive to peonidin 3-glucoside and cyanidin 3-glucoside. Treatment with peonidin 3-glucoside or cyanidin 3-glucoside resulted in a strong inhibitory effect on cell growth via G2/M arrest. Regarding cell cycle–related proteins, peonidin 3-glucoside treatment resulted in down-regulation of protein levels of cyclin-dependent kinase (CDK)-1, CDK-2, cyclin B1, and cyclin E, whereas cyanidin 3-glucoside could decrease the protein levels of CDK-1, CDK-2, cyclin B1, and cyclin D1. In addition, cyanidin 3-glucoside or peonidin 3-glucoside also induced caspase-3 activation, chromatin condensation, and cell death. Furthermore, anthocyanins from O. sativa L. indica were evidenced by their inhibition on the growth of Lewis lung carcinoma cells in vivo.

Silibinin inhibits the invasion of human lung cancer cells via decreased productions of urokinase-plasminogen activator and matrix metalloproteinase-2†

Cancer metastasis, involving multiple processes and various cytophysiological changes, is a primary cause of cancer death and may complicate the clinical management, even lead to death. Silibinin is a flavonoid antioxidant and wildly used for its antihepatotoxic properties and recent studies have revealed pleiotropic anticancer and antiproliferative capabilities of silibinin. In this study, we first observed that silibinin exerted a dose‐ and time‐dependent inhibitory effect on the invasion and motility, but hardly on the adhesion, of highly metastatic A549 cells in the absence of cytotoxicity. To look at the precise involvement of silibinin in cancer metastasis, A549 cells were treated with silibinin at various concentrations, up to 100 μM, for a defined period and then subjected to gelatin zymography, casein zymography and Western blot to investigate the impacts of silibinin on metalloproteinase‐2 (MMP‐2), urokinase plasminogen activator (u‐PA), and tissue inhibitor of metalloproteinase‐2 (TIMP‐2), respectively. The results showed that a silibinin treatment may decrease the expressions of MMP‐2 and u‐PA in a concentration‐ and time‐dependent manner and enhance the expression of TIMP‐2. Further analysis with semi‐quantitative RT‐PCR showed that silibinin may regulate the expressions of MMP‐2 and u‐PA on the transcriptional level while on the translational or post‐translational level for TIMP‐2.

Silibinin Inhibits Invasion of Oral Cancer Cells by Suppressing the MAPK Pathway

Oral squamous cell carcinoma (OSCC) is the most common malignancy of the oral cavity. Here, we provide molecular evidence associated with the anti-metastatic effect of silibinin by showing a marked inhibition of the invasion and motility of SCC-4 tongue cancer cells, with 89% and 66.4% of inhibition, respectively, by 100 μM of silibinin. This effect was associated with a reduced expression of MMP-2 and u-PA, together with an enhanced expression of TIMP-2 and PAI-1. Silibinin also exerted an inhibitory effect on the phosphorylation of ERK1/2. Additionally, pre-treatment of SCC-4 cancer cells with 10 and 20 μM of U0126, a specific MEK inhibitor, resulted in a reduced expression of MMP-2 (18.7 and 51.4%) and u-PA (19.2 and 48.9%) concomitantly with a marked inhibition of cell invasion (13.7 and 45.7%). Finally, silibinin was evidenced by its inhibition of the metastasis of Lewis lung carcinoma (LLC) cells in vivo. These results suggested that silibinin can reduce the invasion and metastasis of tumor cells, and such a characteristic may be of great value in the development of a potential cancer therapy.

Epigallocatechin-3 Gallate Inhibits Invasion, Epithelial-Mesenchymal Transition, and Tumor Growth in Oral Cancer Cells

Epithelial to mesenchymal transition (EMT) is critical for the progression, invasion, and metastasis of epithelial tumorgenesis. Here, we provided molecular evidence associated with the antimetastatic effect of green tea polyphenol epigallocatechin-3 gallate (EGCG) in an oral squamous cell culture system by showing a nearly complete inhibition on the invasion (P < 0.001) of squamous cell carcinoma-9 (SCC-9) cells via a reduced expression of matrix metalloproteinase-2 (P < 0.001) and urokinasetype plasminogen activator (P < 0.001). EGCG exerted an inhibitory effect on cell migration (P < 0.001), motility (P < 0.001), spread, and adhesion (P < 0.001). We performed Western blot to find that EGCG inhibited p-focal adhesion kinase (p-FAK), p-Src, snail-1, and vimentin, indicating the anti-EMT effect of EGCG in oral squamous cell carcinoma. EGCG was also sufficient to inhibit phorbol-12-myristate-13-acetate-induced cell invasion and matrix metalloproteinase-9 expression, as evidenced by its inhibition on the tumor growth of SCC-9 cells in vivo via cancer cell xenografted nude mice mode. These results suggested that EGCG could reduce the invasion and cell growth of tumor cells, and such a characteristic may be of great value in developing a potential cancer therapy.

Impairment of tumor‐initiating stem‐like property and reversal of epithelial–mesenchymal transdifferentiation in head and neck cancer by resveratrol treatment

SCOPE Recent reports have demonstrated that head and neck cancer-derived tumor-initiating cells (HNC-TICs) presented high tumorigenic, chemoradioresistant, metastatic properties, and were coupled with gain of epithelial-mesenchymal transition (EMT) characteristics. The aim of this study was to investigate the chemotherapeutic effect and regulatory mechanisms of resveratrol on HNC-TICs. METHODS AND RESULTS We first observed that the treatment of resveratrol significantly downregulated the ALDH1 activity and CD44 positivity of head and neck cancer (HNC) cells in a dose-dependent manner (p < 0.05). Moreover, resveratrol treatment reduced self-renewal property and stemness genes signatures (Oct4, Nanog, and Nestin) expression in sphere-forming HNC-TICs. Additionally, the repressive effect of resveratrol on in vitro malignant properties including invasiveness/anchorage-independent growth was mediated by regulating productions of EMT markers Slug, ZEB1, N-cadherin, E-cadherin, and Vimentin. Importantly, an in vivo nude mice model showed that resveratrol treatment to xenograft tumors by oral gavage reduced tumor growth, stemness, and EMT markers in vivo. Lastly, synergistic effect of resveratrol and conventional chemotreatment attenuated tumor-initiating cells property in HNC-TICs. CONCLUSIONS Our results demonstrated that resveratrol would be a valuable therapeutics clinically in combination with conventional chemotherapy treatment modalities for malignant HNCs by elimination of tumor-initiating stem-like and EMT properties.

Kaempferol reduces matrix metalloproteinase-2 expression by down-regulating ERK1/2 and the activator protein-1 signaling pathways in oral cancer cells.

Background Kaempferol has been proposed as a potential drug for cancer chemoprevention and treatment because it is a natural polyphenol contained in plant-based foods. Recent studies have demonstrated that kaempferol protects against cardiovascular disease and cancer. Based on this finding, we investigated the mechanisms by which kaempferol produces the anti-metastatic effect in human tongue squamous cell carcinoma SCC4 cells. Methodology/Principal Findings In this study, we provided molecular evidence associated with the anti-metastatic effect of kaempferol by demonstrating a substantial suppression of SCC4 cell migration and invasion. This effect was associated with reduced expressions of MMP-2 and TIMP-2 mRNA and protein levels. Analysis of the transcriptional regulation indicated that kaempferol inhibited MMP-2 transcription by suppressing c-Jun activity. Kaempferol also produced an inhibitory effect on the phosphorylation of ERK1/2. Conclusions These findings provide new insights into the molecular mechanisms involved in the anti-metastatic effect of kaempferol, and are valuable in the prevention of oral cancer metastasis.

Role of Reactive Oxygen Species-Related Enzymes in Neuropeptide Y and Proopiomelanocortin-Mediated Appetite Control: A Study Using Atypical Protein Kinase C Knockdown

AIMS Studies have reported that redox signaling in the hypothalamus participates in nutrient sensing. The current study aimed to determine if the activation of reactive oxygen species-related enzymes (ROS-RE) in the hypothalamus participates in regulating neuropeptide Y (NPY)-mediated eating. Moreover, possible roles of proopiomelanocortin (POMC) and atypical protein kinase C (aPKC) were also investigated. Rats were treated daily with phenylpropanolamine (PPA) for 4 days. Changes in the expression levels of ROS-RE, POMC, NPY, and aPKC were assessed and compared. RESULTS Results showed that ROS-RE, POMC, and aPKC increased, with a maximal response on Day 2 (anorectic effect) and with a restoration to the normal level on Day 4 (tolerant effect). By contrast, NPY expression decreased, and the expression pattern of NPY proved opposite those of ROS-RE and POMC. Central inhibition of ROS production by ICV infusion of ROS scavenger attenuated PPA anorexia, revealing a crucial role of ROS in regulating eating. Cerebral aPKC knockdown by ICV infusion of antisense aPKC modulated the expression of ROS-RE, POMC, and NPY. CONCLUSION Results suggest that ROS-RE/POMC- and NPY-containing neurons function reciprocally in regulating both the anorectic and tolerant effects of PPA, while aPKC is upstream of these regulators. INNOVATION These results may further the understanding of ROS-RE and aPKC in the control of PPA anorexia.

Peonidin 3-Glucoside Inhibits Lung Cancer Metastasis by Downregulation of Proteinases Activities and MAPK Pathway

Anthocyanins, present in various vegetables and fruits as a nature colorant, have broad activities including anticarcinogenesis and antimutagenesis, which are generally attributed to their antioxidant activities. However, limited studies have been available concerning the inhibitory effect of peonidin 3-glucoside (P3G) for cancer metastasis. Here, we demonstrated that P3G could significantly inhibit the invasion (P < 0.001), motility (P < 0.05), secretion of matrix metalloproteinase (MMP)-2, MMP-9, and urokinase-type plasminogen activator (u-PA) of lung cancer cells. Meanwhile, P3G attenuated phosphorylation of extracellular signal-regulated kinase (ERK)1/2, a member of mitogen-activated protein kinase (MAPK) family involved in the upregulation of MMPs and u-PA, and also inhibited the activation of activating protein-1 (AP-1) as shown by Western blot and electrophoretic mobility shift assay. Thus, the inhibitory effects of P3G may be at least partly through inactivation of ERK 1/2 and AP-1 signaling pathways as confirmed by abolishment of P3G-inhibited H1299 cell invasion by overexpression of MAPK kinase 1 (MEK1). Finally, P3G was evidenced by its inhibition on the metastasis of Lewis lung carcinoma cells in vivo (P < 0.001). Taken together, these findings suggested that P3G could reduce the metastasis of lung cancer cells, thereby constituting an adjuvant treatment for metastasis control.

Antimetastatic Potentials of Dioscorea nipponica on Melanoma In Vitro and In Vivo.

Recent studies have revealed pleiotropic anticancer and antiproliferative capabilities of Dioscorea nipponica Makino whereas the effect of this plant on metastasis of cancer cells has not been clearly clarified. In the present study, we extracted Dioscorea nipponica Makino with methanol (DNE1), chloroform (DNE2), ethyl acetate (DNE3), n-butanol (DNE4), and water (DNE5). We first demonstrate that DNE3 was found to be effective in reducing the lung metastases formation by about 99.5% as compared to vehicle-treated control animals. When a nontoxic concentration of the extract was treated directly to highly metastatic murin melanoma cells (B16F10) and human melanoma cells (A2058) in vitro, it exerted a dose-dependent inhibitory effect on the invasion (P < .001), motility (P < .001), secretion of MMPs (P < .001), and u-PA (P < .001) of both cell lines. To investigate the possible mechanisms involved in these events, we performed western blot analysis to find that DNE inhibited phosphorylation of Akt. A treatment with DNE3 to B16F10 cells also inhibited the activation of NF-κB and increased the expression of IkappaB. Taken together, these findings suggested that DNE3 could reduce the metastasis of melanoma cells, thereby constituting an adjuvant treatment for metastasis control.

Berberine reverses epithelial-to-mesenchymal transition and inhibits metastasis and tumor-induced angiogenesis in human cervical cancer cells.

Metastasis is the most common cause of cancer-related death in patients, and epithelial-to-mesenchymal transition (EMT) is essential for cancer metastasis, which is a multistep complicated process that includes local invasion, intravasation, extravasation, and proliferation at distant sites. When cancer cells metastasize, angiogenesis is also required for metastatic dissemination, given that an increase in vascular density will allow easier access of tumor cells to circulation, and represents a rational target for therapeutic intervention. Berberine has several anti-inflammation and anticancer biologic effects. In this study, we provided molecular evidence that is associated with the antimetastatic effect of berberine by showing a nearly complete inhibition on invasion (P < 0.001) of highly metastatic SiHa cells via reduced transcriptional activities of matrix metalloproteinase-2 and urokinase-type plasminogen activator. Berberine reversed transforming growth factor-β1–induced EMT and caused upregulation of epithelial markers such as E-cadherin and inhibited mesenchymal markers such as N-cadherin and snail-1. Selective snail-1 inhibition by snail-1–specific small interfering RNA also showed increased E-cadherin expression in SiHa cells. Berberine also reduced tumor-induced angiogenesis in vitro and in vivo. Importantly, an in vivo BALB/c nude mice xenograft model and tail vein injection model showed that berberine treatment reduced tumor growth and lung metastasis by oral gavage, respectively. Taken together, these findings suggested that berberine could reduce metastasis and angiogenesis of cervical cancer cells, thereby constituting an adjuvant treatment of metastasis control.