Antitumorigenic effect of atmospheric-pressure dielectric barrier discharge on human colorectal cancer cells via regulation of Sp1 transcription factor.

Human colorectal cancer cell lines (HT29 and HCT116) were exposed to dielectric barrier discharge (DBD) plasma at atmospheric pressure to investigate the anticancer capacity of the plasma. The dose- and time-dependent effects of DBDP on cell viability, regulation of transcription factor Sp1, cell-cycle analysis, and colony formation were investigated by means of MTS assay, DAPI staining, propidium iodide staining, annexin V-FITC staining, Western blot analysis, RT-PCR analysis, fluorescence microscopy, and anchorage-independent cell transformation assay. By increasing the duration of plasma dose times, significant reductions in the levels of both Sp1 protein and Sp1 mRNA were observed in both cell lines. Also, expression of negative regulators related to the cell cycle (such as p53, p21, and p27) was increased and of the positive regulator cyclin D1 was decreased, indicating that the plasma treatment led to apoptosis and cell-cycle arrest. In addition, the sizes and quantities of colony formation were significantly suppressed even though two cancer promoters, such as TPA and epidermal growth factor, accompanied the plasma treatment. Thus, plasma treatment inhibited cell viability and colony formation by suppressing Sp1, which induced apoptosis and cell-cycle arrest in these two human colorectal cancer cell lines.

Kahweol induces apoptosis by suppressing BTF3 expression through the ERK signaling pathway in non-small cell lung cancer cells.

Kahweol, a diterpene molecule, has antiproliferative effects on several types of human cancer cells, but whether it has apoptotic effect in non-small cell lung cancer (NSCLC) is not known. To explore this possibility, we incubated cells from two NSCLC cell lines, NCI-H358 and NCI­H1299, with different concentrations of kahweol and used the MTS assay, DAPI staining, propidium iodide staining, Annexin V staining, immunocytochemical test, and western blot analysis to characterize this molecule and the signaling pathway underlying its effects. The kahweol-treated cells showed significantly decreased cell viability, increased nuclear condensation, and an increased number of Annexin V-positive NSCLC cells. Suppression of basic transcription factor 3 (BTF3) was followed by apoptosis induced by kahweol via the ERK-mediated signaling pathway in a dose- and time-dependent manner. In addition, kahweol modulated the protein expression of BTF3 genes involved in cell-cycle regulation and apoptosis-related proteins, resulting in apoptotic cell death. Our results collectively indicated that kahweol inhibited the proliferation of NSCLC cells through ERK-mediated signaling pathways and the downregulation of BTF3.

ß-lapachone suppresses the proliferation of human malignant melanoma cells by targeting specificity protein 1.

ß-lapachone (ß-lap), a novel natural quinone derived from the bark of the Pink trumpet tree (Tabebuia avellanedae) has been demonstrated to have anticancer activity. In this study, we investigated whether ß-lap exhibits anti-proliferative effects on two human malignant melanoma (HMM) cell lines, G361 and SK-MEL-28. The effects of ß-lap on the HMM cell lines were investigated using 3-(4,5-dimethylthiazol-2-yl)­5-(3-carboxymethoxyphenyl)­2-(4-sulfophenyl-2H-tetrazolium (MTS) assay, 4',6-diamidino-2-phenylindole (DAPI) staining, Annexin V and Dead cell assay, mitochondrial membrane potential (MMP) assay and western blot analysis. We demonstrated that ß-lap significantly induced apoptosis and suppressed cell viability in the HMM cells. Intriguingly, the transcription factor specificity protein 1 (Sp1) was significantly downregulated by ß-lap in a dose- and time-dependent manner. Furthermore, ß-lap modulated the protein expression level of the Sp1 regulatory genes including cell cycle regulatory proteins and apoptosis-associated proteins. Taken together, our findings indicated that ß-lap modulates Sp1 transactivation and induces apoptotic cell death through the regulation of cell cycle- and apoptosis-associated proteins. Thus, ß-lap may be used as a promising anticancer drug for cancer prevention and may improve the clinical outcome of patients with cancer.

Beta-Lapachone Suppresses Non-small Cell Lung Cancer Proliferation through the Regulation of Specificity Protein 1.

Lung cancer is the leading cause of cancer-related death worldwide, and non-small cell lung cancer (NSCLC) is the most common pathological type with a reported frequency of about 85% of all cases. Despite recent advances in therapeutic agents and targeted therapies, the prognosis for NSCLC remains poor, and therefore it is important to identify the biological targets of this complex disease since a blockade of such targets would affect multiple downstream signaling cascades. ß-Lapachone (ß-Lap) is an antiproliferative agent that selectively induces apoptosis-related cell death in a variety of human cancer cells. However, the mechanisms of its action require further investigation. In this study, we show that treatment with ß-lap triggers apoptosis and cell-cycle arrest in two NSCLC cell lines: H1299 and NCI-H358. The transcription factor specificity protein 1 (Sp1) was markedly inhibited by ß-lap in a dose- and time-dependent manner. Furthermore, ß-lap modulated the protein expression levels of the Sp1 regulatory genes, including cell-cycle regulatory proteins and antiapoptotic proteins, resulting in apoptosis. Taken together, our results indicate that ß-lap may be a potential antiproliferative agent candidate by inducing apoptotic cell death in NSCLC tissue through downregulation of Sp1.

Downregulation of Sp1 is involved in ß-lapachone-induced cell cycle arrest and apoptosis in oral squamous cell carcinoma.

ß-lapachone (ß-lap) is a naturally occurring quinone obtained from the bark of lapacho tree (Tabebuia avellanedae) with anti-proliferative properties against various cancers. The present study investigated the cell proliferation and apoptosis effect of ß-lap on two oral squamous cell carcinoma lines (OSCCs). We carried out a series of 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl-2H-tetrazolium (MTS) assays, 4',6-diamidino-2-phenylindole (DAPI) staining, cell cycle analysis, and western blot analysis to characterize ß-lap and its underlying signaling pathway. We demonstrated that ß-lap-treated cells significantly reduced cell proliferation but increased DNA condensation and increased sub-G1 population in OSCCs. Particularly, ß-lap suppresses activation of transcription factor specificity protein 1 (Sp1) followed by apoptosis in a concentration-dependent manner in OSCCs. Furthermore, ß-lap modulated protein expression levels of cell cycle regulatory proteins and apoptosis-related proteins that are known as Sp1 target genes, resulting in apoptosis. Our results collectively indicated that ß-lap was able to modulate Sp1 transactivation and induce apoptosis through the regulation of cell cycle and apoptosis-related proteins. Therefore, ß-lap may be used in cancer prevention and therapies to improve clinical outcome as an anticancer drug candidate.

Quercetin Induces Antiproliferative Activity Against Human Hepatocellular Carcinoma (HepG2) Cells by Suppressing Specificity Protein 1 (Sp1).

Preclinical Research Quercetin, found in red onions and red apple skin can induce apoptosis insome malignant cells. However, the apoptotic effect of quercetin in hepatocellular carcinoma HepG2 cells via regulation of specificity protein 1 (Sp1) has not been studied. Here, we demonstrated that quercetin decreased cell growth and induce apoptosis in HepG2 cells via suppression of Sp1 using 3-(4,5-dimethyl-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assay, 4',6-diamidino-2-phenylindole (DAPI) staining, Annexin V, and Western blot analysis, an effect that was dose- and time-dependent manner. Treatment of HepG2 cells with quercetin reduced cell growth and induced apoptosis, followed by regulation of Sp1 and Sp1 regulatory protein. Taken together, the results suggest that quercetin can induce apoptotic cell death by regulating cell cycle and suppressing antiapoptotic proteins. Therefore, quercetin may be useful for cancer prevention. Drug Dev Res 76 : 9-16, 2015.