SP1-regulated p27/Kip1 gene expression is involved in terbinafine-induced human A431 cancer cell differentiation: An in vitro and in vivo study

The Exploitation of pH-Responsive Eudragit-Coated Mesoporous Silica Nanostructures in the Repurposing of Terbinafine Hydrochloride for Targeted Colon Cancer Inhibition: Design Optimization, In Vitro Characterization, and Cytotoxicity Assessment

Targeted drug delivery is achieving great success in cancer therapy due to its potential to deliver drugs directly to the action site. Terbinafine hydrochloride (TER) is a broad-spectrum anti-fungal drug that has been found to have some potential anti-tumor effects in the treatment of colon cancer. We aimed here to design and develop pH-sensitive Eudragit (Eud)-coated mesoporous silica nanostructures (MSNs) to control drug release in response to changes in pH. The diffusion-supported loading (DiSupLo) technique was applied for loading TER into the MSNs. The formulation was optimized by a D-optimal design, which permits the concurrent assessment of the influence of drug/MSN%, coat concentration, and MSN type on the drug entrapment efficiency (EE) and its release performance. The optimal formula displayed a high EE of 96.49%, minimizing the release in pH 1.2 to 16.15% and maximizing the release in pH 7.4 to 78.09%. The cytotoxicity of the optimal formula on the colon cancer cells HT-29 was higher than it was with TER alone by 2.8-fold. Apoptosis in cancer cells exposed to the optimum formula was boosted as compared to what it was with the plain TER by 1.2-fold and it was more efficient in arresting cells during the G0/G1 and S stages of the cell cycle. Accordingly, the repurposing of TER utilizing Eud/MSNs is a promising technique for targeted colon cancer therapy.

Roscovitine enhances all-trans retinoic acid (ATRA)-induced nuclear enrichment of an ensemble of activated signaling molecules and augments ATRA-induced myeloid cell differentiation

Although ATRA represents a successful differentiation therapy for APL, it is largely ineffective for non-APL AMLs. Hence combination therapies using an agent targeting ATRA-regulated molecules that drive cell differentiation/arrest are of interest. Using the HL-60 human non-APL AML model where ATRA causes nuclear enrichment of c-Raf that drives differentiation/G0-arrest, we now observe that roscovitine enhanced nuclear enrichment of certain traditionally cytoplasmic signaling molecules and enhanced differentiation and cell cycle arrest. Roscovitine upregulated ATRA-induced nuclear c-Raf phosphorylation at S259 and S289/296/301. Nuclear c-Raf interacted with RB protein and specifically with pS608RB, the hinge region phosphorylation controlling E2F binding and cell cycle progression. ATRA-induced loss of pS608RB with cell cycle arrest was associated with loss of RB-sequestered c-Raf, thereby coupling cell cycle arrest and increased availability of c-Raf to promote differentiation. Part of this mechanism reflects promoting cell cycle arrest via ATRA-induced upregulation of the p27 Kip1 CDKI. Roscovitine also enhanced the ATRA-induced nuclear enrichment of other signaling molecules traditionally perceived as cytoplasmic promoters of proliferation, but now known to promote differentiation; in particular: SFKs, Lyn, Fgr; adaptor proteins, c-Cbl, SLP-76; a guanine exchange factor, Vav1; and a transcription factor, IRF-1. Akin to c-Raf, Lyn bound to RB, specifically to pS608RB. Lyn-pS608RB association was greatly diminished by ATRA and essentially lost in ATRA plus roscovitine treated cells. Interestingly Lyn-KD enhanced such ATRA-induced nuclear signaling and differentiation and made roscovitine more effective. ATRA thus mobilized traditionally cytoplasmic signaling molecules to the nucleus where they drove differentiation which were further enhanced by roscovitine.

Jasmonic Acid Induces Endoplasmic Reticulum Stress with Different Outcome in Cultured Normal and Tumor Epidermal Cells

Plant hormones produce cytotoxic effect on human cells and can trigger the processes unrelated to cell death, e.g., biosynthetic system stress. The goal of this study was to investigate activation of the endoplasmic reticulum (ER) stress by jasmonic acid (JA) and to distinguish between the responses of cultured immortalized non-tumorigenic HaCaT cells and epidermoid carcinoma A431 cells to this plant hormone. JA was used in the concentration of 2 mM, as it suppressed cell proliferation in both cell lines. We analyzed expression of genes associated with the activation of ER stress (GRP78, ATF4, CHOP), the structure of the ER and Golgi complex, and synthetic processes in the HaCaT and A431 cell lines. JA induced expression of genes responsible for the activation of ER stress and caused hypertrophic changes in the Golgi complex in both cell lines. However, the patterns of gene expression in the HaCaT and A431 cells were different, and higher levels of involucrin synthesis were observed in A431 but not in HaCaT cells, suggesting that JA activated differentiation of the tumor A431 cells only. Therefore, JA induced ER stress in both cell lines, but the consequences of ER stress were different for the epidermal immortalized non-tumorigenic and tumor cells.

Everolimus (RAD001) inhibits the proliferation of rat vascular smooth muscle cells by up-regulating the activity of the p27/kip1 gene promoter

OBJECTIVE

We investigated whether the inhibitory effect of the immunosuppressant everolimus (RAD001) on vascular smooth muscle cell (VSMC) proliferation is mediated by p27/kip1 gene promoter activity.

METHODS

In this experimental study, cultured rat VSMCs were transiently transfected with a recombinant plasmid (pXp27) containing p27/kip1 gene promoter sequence and a chloramphenicol acetyltransferase (CAT) reporter gene. After stimulation with the mitogen platelet-derived growth factor (PDGF-BB, 10 ng/mL) in the presence or absence of RAD001 (10 nM), the promoter activity, mRNA expression, and protein expression of p27/kip1 were examined by CAT assay, RT-PCR, and immunoblotting, respectively. Cell cycle-related changes were detected by flow cytometry. DNA synthesis was determined using 3H-TdR incorporation.

RESULTS

Compared with the non-stimulation group, PDGF-BB stimulation induced a significant proliferative response in the VSMCs as indicated by decreased p27/kip1 gene promoter activity, decreased p27/kip1 mRNA and protein expression, increased S-phase and G2/M-phase cells, and increased DNA synthesis. RAD001 intervention increased p27/kip1 gene promoter activity 3.5-fold, promoted p27/kip1 mRNA and protein expression, increased G0-phase cells, reduced DNA synthesis, and, overall, inhibited PDGF-BB-stimulated cell proliferation.

CONCLUSION

RAD001 inhibits PDGF-BB-stimulated proliferation of cultured VSMCs by upregulating p27/kip1 gene promoter activity and increasing p27/kip1 mRNA and protein expression.

Inhibition of specificity protein 1 by dibenzylideneacetone, a curcumin analogue, induces apoptosis in mucoepidermoid carcinomas and tumor xenografts through Bim and truncated Bid

OBJECTIVES

Dibenzylideneacetone (DBA), a curcumin analogue that has anti-cancer activity in a variety of tumor cells. In this study, we investigated the apoptotic effects of DBA and its molecular mechanism in human mucoepidermoid carcinoma (MEC) cell lines and tumor xenografts.

MATERIAL AND METHODS

The apoptotic effects and related molecular mechanisms of DBA on MEC cell lines were evaluated using cell viability assay, DAPI staining, Western blot analysis, reverse transcriptase-polymerase chain reaction (RT-PCR) and Dual-luciferase Reporter Assay. The anti-tumor activity using in vivo were determined by Nude mouse xenograft assay and histopathological examination.

RESULTS

DBA decreased cell viability and induced apoptosis in MEC cells. These events were accompanied by inhibition of specificity protein 1 (Sp1). DBA did not induce major changes in Sp1 mRNA and promoter activity. Furthermore, inhibition of protein synthesis by cycloheximide demonstrated that DBA decreased Sp1 protein stability, but DBA did not attenuate phosphorylation of eIF4E. DBA also increased Bim and truncated Bid (t-Bid) via Sp1. Finally, DBA exhibited significant anti-tumor activity in athymic nude mice xenografts bearing MC-3 cells by regulating Sp1, Bim and t-Bid without any systemic toxicity.

CONCLUSION

These results elucidate a crucial apoptotic mechanism of DBA and suggest that DBA may be a potent anticancer drug candidate for MEC.

P27/Kip1 is responsible for magnolol-induced U373 apoptosis in vitro and in vivo

Previously, we demonstrated that magnolol, a hydroxylated biphenyl compound isolated from the bark of Magnolia officinalis, at low concentrations (3-10 μM) exerted an antiproliferation effect in colon cancer, hepatoma, and glioblastoma (U373) cell lines through upregulation of the p21/Cip1 protein. Magnolol at a higher concentration of 100 μM, however, induced apoptosis and upregulated p27/Kip1 expression in U373. In the present study, we further studied whether the increased p27/Kip1 expression contributes to the magnolol-induced apoptosis in U373. Our data show that knock-down of p27/Kip1 expression significantly suppressed the magnolol-induced apoptosis, suggesting that p27/Kip1 might play an important role in the regulation of magnolol-induced apoptosis. This notion was further supported by demonstrating that magnolol induced an increase of the caspase activity in U373 in vitro and in vivo, and these effects were abolished by pretransfection of the cell with p27/Kip1 siRNA. To delineate the possible signaling pathways involved in the magnolol-induced increases of p27/Kip1 expression and apoptosis, we found that magnolol (100 μM) increased the levels of phosphorylated cSrc (p-cSrc), p-ERK, p-p38 MAP kinase (p-p38 MAPK), and p-AKT but not p-JNK in U373. Moreover, pretreatment of U373 with a cSrc inhibitor (PP2), a PI3K inhibitor (LY294002), an ERK inhibitor (PD98059), or a p38 MAPK inhibitor (SB203580) but not a JNK inhibitor (SP600125) significantly reduced the magnolol-induced increases of p27/Kip1 protein levels and apoptosis. Taken together, our data suggest that magnolol at a higher concentration of 100 μM induced apopotosis in U373 cells through cSrc-mediated upregulation of p27/Kip1.

In vivo antitumor effects of 4,7-dimethoxy-5-methyl-1,3-benzodioxole isolated from the fruiting body of Antrodia camphorata through activation of the p53-mediated p27/Kip1 signaling pathway

In this study, 4,7-dimethoxy-5-methyl-1,3-benzodioxole (SY-1) was isolated from three different sources of dried Antrodia camphorata (AC) fruiting bodies. AC is a medicinal mushroom that grows on the inner heartwood wall of Cinnamomum kanehirai Hay (Lauraceae), which is an endemic species that is used in Chinese medicine for its antitumor properties. We demonstrated that SY-1 [given as a 1-30 mg/kg body weight intraperitoneal (ip) injection three times per week] profoundly decreased the growth of COLO-205 human colon cancer cell tumor xenografts in an athymic nude mouse model. We further demonstrated that significant AC extract-mediated antitumor effects were observed at the highest concentration (5 g/kg body weight/day). No gross toxicity signs were observed (i.e., body weight changes, general appearance, or individual organ effects). Frozen COLO-205 xenograft tumors were pulverized in liquid N(2), and the expression of cell cycle regulatory proteins was detected by immunoblotting. We found that the p53-mediated p27/Kip1 protein was significantly induced in the low-dose (1 mg/kg body weight) SY-1-treated tumors, whereas the p21/Cip1 protein levels did not change. The G0/G1 phase cell cycle regulators induced by SY-1 were also associated with a significant decrease in cyclins D1, D3, and A. These results provide further evidence that SY-1 may have significance for cancer chemotherapy.

Apoptotic effect of tolfenamic acid in androgen receptor-independent prostate cancer cell and xenograft tumor through specificity protein 1

Tolfenamic acid (Tol) is a non-steroidal anti-inflammatory drug that was reported to exhibit anticancer activity in pancreatic and colorectal cancer models. This study examined the role of Tol in the death regulation of PC-3 and DU145 human androgen-independent prostate cancer cells. The results showed that Tol inhibited cell growth and induced apoptosis, as evidenced by nuclear fragmentation and cleaved caspase 3 and poly(ADP-ribose) polymerase. Tol suppressed the specificity protein 1 (Sp1) protein in both PC-3 and DU145 cells. Tol also attenuated Sp1 mRNA and its promoter activity in DU145 cells, but did not alter them in PC-3 cells, indicating that Tol degrades Sp1 protein in these cells. Tol also downregulated protein levels, mRNA levels and promoter activities of survivin and myeloid cell leukemia-1, which are downstream targets of Sp1. The expressions of survivin and Mcl-1 and cancer cell growth were lower in the PC-3 cells treated with Sp1 interfering RNA and mithramycin A. Moreover, an oral injection of Tol decreased tumor growth and downregulated the Sp1 protein in athymic nude mice bearing DU145 cell xenografts without hepatotoxicity. Overall, Tol downregulates the Sp1 protein to inhibit growth and induce apoptosis in androgen-refractory prostate cancers, both in vitro and in vivo, that show resistance against many chemotherapeutic agents.

Regulation of gene transcription and keratinocyte differentiation by anandamide

Anandamide (AEA) is a member of an endogenous class of lipid mediators, known as endocannabinoids, which are involved in various biological processes. In particular, AEA regulates cell growth, differentiation, and death. Accumulating evidence demonstrates that AEA controls also epidermal differentiation, one of the best characterized mechanisms of cell specialization. Indeed, the epidermis is a keratinized multistratified epithelium that functions as a barrier to protect the organism from dehydration, mechanical trauma, and microbial insults. Its function is established during embryogenesis and is maintained during the whole life span of the organism, through a complex and tightly controlled program, termed epidermal terminal differentiation (or cornification). Whereas the morphological changes that occur during cornification have been extensively studied, the molecular mechanisms that underlie this process remain poorly understood. In this chapter, we summarize current knowledge about the molecular regulation of proliferation and terminal differentiation in mammalian epidermis. In this context, we show that endocannabinoids are finely regulated by, and can interfere with, the differentiation program. In addition, we review the role of AEA in the control of cornification, and show that it occurs by maintaining a transcriptional repression of gene expression through increased DNA methylation.