Upregulation Of CDK Inhibitors Research Articles

High therapeutic efficacy of 5-Fluorouracil-loaded exosomes against colon cancer cells.

The successful chemotherapeutic regime required for the clinical management of different cancers largely depends on the efficient drug delivery within the cancer cells. Exosomes have emerged as an enticing candidate for exploring their role as delivery vehicles. Exosomes are reported to be intrinsically nanosized vesicles competent for efficient delivery across the cellular membrane. In the present study, we assessed the feasibility of an autologous exosome-based drug delivery platform for delivering 5-Fluorouracil (5-FU) against human colon cancer HCT116 cells. Autologous exosomes have shown probable tropism toward the tumor microenvironment, which makes them the most competitive vehicle for drug delivery. It was observed that the autologous exosomes loaded with 5-FU showed an enhanced rate of drug release under acidic conditions. The result of the cell viability assay showed that treatment of 5-FU-loaded exosomes (equivalent to 5μg 5-FU) resulted in enhanced cytotoxic effect in HCT116 cells as compared to an equivalent amount of free 5-FU (5μg), which elucidated the efficient delivery of the 5-FU by exosomes inside the cancer cells. Subsequently, 5-FU-loaded exosomes led to increased nuclear condensation and fragmentation along with increased ROS production. In addition, 5-FU-loaded exosomes caused enhanced dissipation of mitochondrial membrane potential and caspase-3 activation, resulting in increased apoptosis induction. Our study also revealed that 5-FU-loaded exosomes upsurged the arrest in the cell cycle at the G0/G1 stage in HCT-116 cells and it was found to be associated with decreased CDK4 and Cyclin D1 expression concomitantly with the upregulation of CDK inhibitor, p21Cip1 expression. Thus, the findings from the present study highlight the advantages of autologous exosomes as a natural drug carrier which could efficiently deliver chemotherapeutic drugs to cancer cells.

Secreted Ly-6/uPAR-related protein-1 (SLURP1) is a pro-differentiation factor that stalls G1-S transition during corneal epithelial cell cycle progression

PurposePreviously we demonstrated that the secreted Ly-6/uPAR related protein-1 (SLURP1), abundantly expressed in the corneal epithelium (CE) and secreted into the tear fluid, serves as an anti-inflammatory and anti-angiogenic molecule. Here we describe the Slurp1-null (Slurp1X−/−) mouse corneal phenotype for the first time. MethodsWe compared the 10-week-old wild type (WT) and Slurp1X−/− mouse corneal (i) histology by hematoxylin-eosin and periodic acid-Schiff's reagent staining, (ii) cell proliferation by immunostaining for Ki67, (iii) cell adhesion molecules by immunostaining for desmosomal and tight junction proteins, (iv) barrier function by fluorescein staining and (v) wound-healing by epithelial debridement. Effect of SLURP1 on cell cycle was quantified in human corneal limbal epithelial (HCLE) cells engineered to express SLURP1 (HCLE-SLURP1). ResultsWT and Slurp1X−/− corneal histology was largely comparable, other than a few loosely attached superficial cells in Slurp1X−/− corneas. Compared with the WT, Slurp1X−/− corneas displayed (i) increase in Ki67+ cells, (ii) altered expression and/or localization of tight junction proteins Tjp1 and Pard3, and desmosomal Dsp, (iii) increased superficial fragility and (iv) slower CE wound healing. HCLE-SLURP1 cells displayed (i) decrease in Ki67+ cells, (ii) increased cell number doubling time, (iii) stalling in G1-S phase transition during cell cycle, and (iv) downregulation of cyclins CCNE and CCND1/D2, cyclin-dependent kinases CDK4 and CDK6, and upregulation of CDK inhibitor p15/CDKN2B. ConclusionsCollectively, these results elucidate that Slurp1X−/− CE cell homeostasis is altered and suggest that SLURP1 is a pro-differentiation factor that stalls G1-S transition during cell cycle progression by downregulating cyclins and upregulating p15/CDKN2B.

Sauchinone Protects Renal Mesangial Cell Dysfunction against Angiotensin II by Improving Renal Fibrosis and Inflammation.

Abnormal and excessive growth of mesangial cells is important in the pathophysiologic processes of diabetes-associated interstitial fibrosis and glomerulosclerosis, leading to diabetic nephropathy, which eventually turns into end-stage renal disease. Sauchinone, a biologically-active lignan isolated from aerial parts of Saururus chinensis, has anti-inflammatory and anti-viral activities effects on various cell types. However, there are no studies reporting the effects of sauchinone on diabetic nephropathy. The present study aims to investigate the role of sauchinone in mesangial cell proliferation and fibrosis induced by angiotensin II, as well as the underlying mechanisms of these processes. Human renal mesangial cells were induced by angiotensin II (AngII, 10 μM) in the presence or absence of sauchinone (0.1–1 μM) and incubated for 48 h. In this study, we found that AngII induced mesangial cell proliferation, while treatment with sauchinone inhibited the cell proliferation in a dose-dependent manner. Pre-treatment with sauchinone induced down-regulation of cyclins/CDKs and up-regulation of CDK inhibitor, p21, and p27kip1 expression. In addition, AngII-enhanced expression of fibrosis biomarkers such as fibronectin, collagen IV, and connective tissue growth factor (CTGF), which was markedly attenuated by sauchinone. Sauchinone also decreased AngII-induced TGF-β1 and Smad-2, Smad-3, and Smad-4 expression. This study further revealed that sauchinone ameliorated AngII-induced mesangial inflammation through disturbing activation of inflammatory factors, and NLRP3 inflammasome, which is composed of the NLRP3 protein, procaspase-1, and apoptosis-associated speck-like protein containing a CARD (ASC). Moreover, pretreatment of sauchinone inhibited NF-κB translocation and ROS production in AngII-exposed mesangial cells. These data suggest that sauchinone has a protective effect on renal proliferation, fibrosis and inflammation. Therefore, sauchinone might be a potential pharmacological agent in prevention of AngII-induced renal damage leading to diabetic nephropathy.

Organosulphur Compounds Induce Apoptosis and Cell Cycle Arrest in Cervical Cancer Cells via Downregulation of HPV E6 and E7 Oncogenes.

The quest for strong, safe and cost-effective natural antiproliferative agents that could reduce cancer has been the focus now a days. In this regard, the organosulfur compounds from garlic (Allium sativum L.), like Diallyl Sulfide (DAS) and Diallyl Disulfide (DADS), have been shown to exhibit potent antiproliferative and anticancer properties in many studies. However, the potential of these compounds against viral oncoproteins in cervical cancer has not been fully elucidated yet. The objective of this study was to analyze the antiproliferative and apoptotic properties of DADS and DAS in HPV16+ human cervical cancer Caski cell line. Caski (cervical cancer cells) were cultured and followed by the treatment of various concentrations of organosulphur compounds (DADS and DAS), cell viability was measured by MTT assay. The apoptotic assay was performed by DAPI and Hoechst3342 staining. Reactive Oxygen Species (ROS) was estimated by DCFDA staining protocol. The distributions of cell cycle and apoptosis (FITC-Annexin V assay) were analyzed by flow cytometry. Finally, gene expression analysis was performed via quantitative real time PCR. Our results showed that DAS and DADS exerted a significant antiproliferative effect on Caski cells by reducing the cell viability and inducing a dose-related increment in intracellular ROS production along with apoptosis in Caski cells. DAS and DADS also induced cell cycle arrest in G0/G1 phase, which was supported by the downregulation of cyclin D1 and CDK4 and upregulation of CDK inhibitors p21WAF1/CIP1 and p27KIP1 in Caski cells. Additionally, DAS and DADS lead to the downregulation of viral oncogene E6 and E7 and restoration of p53 function. Thus, this study confirms the efficacy of both the organosulfur compounds DADS and DAS against cervical cancer cells.

Abstract 307: TRIB3 regulates cell cycle progression and programmed cell death in non-small cell lung cancer

Abstract Introduction: The pseudokinase Tribbles pseudokinase 3 (TRIB3) is known as a regulator in cellular responses to a variety of stresses such as glucose insufficiency and (ER) stress. TRIB3 has been described in some studies as a tumor suppressor due to its effect on inactivating PI3K/Akt pathway, but other studies suggest TRIB3 as a stimulator of tumor progression. In this study, we aimed to define the functions of TRIB3 in in non-small cell lung cancer. Methods: TRIB3 expression was altered using a lentiviral vector to overexpress TRIB3 in non-small cell lung cancer. A CRISPR-CAS9 construct with guiding sequence matching to TRIB3 gene was used to knock out its expression. Cell proliferation was evaluated using MTS and trypan blue assays. Boyden chamber assay was used to assess the cell migration while cell cycle phases were determined using flow cytometry. Heatmap analysis was performed to assess the changes in the expressions of genes in cell cycle progression and apoptosis. Results: TRIB3 overexpression led to reduced cell proliferation and migration. Moreover, it contributed to the increased of cell cycle arrest at G0/G1 phase. QPCR analyses of cell cycle related genes showed an upregulation of CDK inhibitors in (NCI-H358) TRIB3 overexpression cells, while depletion of TRIB3 led to the down-regulation of CDK inhibitors. TRIB3 overexpression led to downregulation of LC3B and other autophagy markers while increasing the expression of apoptotic genes. Conclusion: Increased TRIB3 expression in non-small cell lung cancer cells inhibited proliferation by blocking cell cycle progression through the upregulation of CDK inhibitors, led to activation of cell death through apoptosis. Our study reveals a significant role of TRIB3 in regulating cell cycle progression, apoptosis and autophagy. Citation Format: Abeer Almiman, Daotai Nie, Jamila Adom. TRIB3 regulates cell cycle progression and programmed cell death in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 307. doi:10.1158/1538-7445.AM2017-307

위령탕(胃苓湯) 추출물의 사람 유래 신장 메산지움 세포에서의 당뇨병성 신장 손상 개선 효과

Objectives : Diabetic nephropathy is one of the most common chronic complications of diabetes and a leading cause of end-stage renal failure in the world. Mesangial cell proliferation is known as the major pathologic features such as glomerulosclerosis and renal fibrosis. Wiryeongtang (WRT) is a well-known traditional herbal formula as therapeutic agents for chronic edema and dysuresia of renal homeostasis. In the present study, we investigated whether WRT inhibits high glucose (HG)-induced renal dysfunction by TGF-β/Smads signal regulation in cultured mesangial cells.Methods : Inhibitory effect of WRT (10-50 ㎍/ml) on HG-stimulated mesangial cells proliferation and dysfunction were evaluated by [³H]-thymidine incorporation, Western blot, and RT-qPCR.Results : WRT significantly decreased HG-accelerated thymidine incorporation in human renal mesangial cell in a dose-dependent levels. WRT induced down-regulation of cyclins/CDKs and up-regulation of CDK inhibitor, p21waf1/cip1 and p27kip1 expression. In addition, HG enhanced expression of dysfunction biomarker such as collagen IV and CTGF, which was markedly attenuated by WRT. WRT decreased TGF-β1 and Smad-2/Smad-4 expression, whereas increased Smad-7 expression under HG. Furthermore, WRT inhibited HG-induced inflammatory factors level such as ICAM-1 and MCP-1 as well as NF-κB p65 nuclear translocation and intracellular ROS production.Conclusions : These results suggested that WRT may alleviate mesangial proliferation and inflammation possibly involved in renal fibrotic process, further diabetic nephropathy through disturbing TGF-β1/Smad signaling and NF-κB/ROS pathway. Thus, WRT might prove to be effective in the treatment of renal dysfunction leading to diabetic nephropathy.

Flavokawain C Inhibits Cell Cycle and Promotes Apoptosis, Associated with Endoplasmic Reticulum Stress and Regulation of MAPKs and Akt Signaling Pathways in HCT 116 Human Colon Carcinoma Cells

Flavokawain C (FKC) is a naturally occurring chalcone which can be found in Kava (Piper methysticum Forst) root. The present study evaluated the effect of FKC on the growth of various human cancer cell lines and the underlying associated mechanisms. FKC showed higher cytotoxic activity against HCT 116 cells in a time- and dose-dependent manner in comparison to other cell lines (MCF-7, HT-29, A549 and CaSki), with minimal toxicity on normal human colon cells. The apoptosis-inducing capability of FKC on HCT 116 cells was evidenced by cell shrinkage, chromatin condensation, DNA fragmentation and increased phosphatidylserine externalization. FKC was found to disrupt mitochondrial membrane potential, resulting in the release of Smac/DIABLO, AIF and cytochrome c into the cytoplasm. Our results also revealed that FKC induced intrinsic and extrinsic apoptosis via upregulation of the levels of pro-apoptotic proteins (Bak) and death receptors (DR5), while downregulation of the levels of anti-apoptotic proteins (XIAP, cIAP-1, c-FlipL, Bcl-xL and survivin), resulting in the activation of caspase-3, -8 and -9 and cleavage of poly(ADP-ribose) polymerase (PARP). FKC was also found to cause endoplasmic reticulum (ER) stress, as suggested by the elevation of GADD153 protein after FKC treatment. After the cells were exposed to FKC (60μM) over 18hrs, there was a substantial increase in the phosphorylation of ERK 1/2. The expression of phosphorylated Akt was also reduced. FKC also caused cell cycle arrest in the S phase in HCT 116 cells in a time- and dose-dependent manner and with accumulation of cells in the sub-G1 phase. This was accompanied by the downregulation of cyclin-dependent kinases (CDK2 and CDK4), consistent with the upregulation of CDK inhibitors (p21Cip1 and p27Kip1), and hypophosphorylation of Rb.

Oxidative stress and premature senescence in corneal endothelium following penetrating keratoplasty in an animal model.

BackgroundThe purpose of this study was to address the question of how the premature senescence process may affect corneal endothelium after penetrating keratoplasty, because the quality of donor corneal endothelial cells is important for corneal transplant success.MethodsThe cell senescence and induced oxidative stress in corneal endothelium were assessed using a normal-risk orthotopic mice corneal transplantation model. Senescence associated beta-galactosidase (SA-beta-Gal) staining was used to evaluate premature senescence in the endothelium of corneal allografts. Oxidative Stress and Antioxidant Defense RT2-PCR Arrays and in vitro experimental model using H2O2 treatment were used to investigate the possible mechanism.ResultsSA-beta-Gal positivity was observed obviously in mice corneal endothelium of allogenic group and the levels of p16INK4a message and protein increased in endothelium of allogenic group compared to syngenic group. By PCR array, an oxidant-antioxidant imbalance was found in the endothelium of corneal allograft after PKP. The results from mice model were validated using human endothelium samples of corneal allograft after PKP. We also developed an in vitro experimental model using H2O2 treatment to simulate a state of oxidative stress in cultured human corneal endothelial cells (HCECs) and found that elevated ROS levels, the up-regulation of CDK inhibitors and ROS-mediated p16INK4A up-regulation in HCECs occur via the ASK1-p38 MAPK pathway.ConclusionsOur results demonstrate the presence of oxidative stress and premature senescence in the endothelium of corneal allografts following PKP.Electronic supplementary materialThe online version of this article (doi:10.1186/s12886-016-0192-6) contains supplementary material, which is available to authorized users.

Expression of USP22 and Survivin is an indicator of malignant behavior in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is the most common primary malignant liver tumor type, ranking as the third leading cause of all cancer-related deaths in the world. The post-surgical 5-year survival rate is low, largely due to the high recurrence rate. Therefore, the identification of target molecules that control the biological characteristics of HCC is of great importance. Ubiquitin-specific protease 22 (USP22) is a newly discovered deubiquitinating enzyme and is a cancer stem cell marker that plays a role in tumorigenesis, therapy resistance and cell cycle progression. Survivin is a member of the inhibitor of apoptosis protein (IAP) family and is known to function either as an inhibitor for apoptosis or as a regulator of cell division. Levels of survivin are correlated with the aggressiveness of tumors and a poor prognosis in various cancers including HCC. In the present study, we examined the USP22 expression and its association with survivin expression and clinicopathological features in HCC. First, we examined the expression of USP22 and survivin in 151 HCC cases by immunohistochemistry. High expression of USP22 and survivin was frequently observed in HCC cases, in comparison with normal adjacent liver tissues. Expression of USP22 and survivin was well correlated with malignant behavior including tumor size, stage and differentiation in HCC cases. Importantly, HCC patients with high expression of USP22 and survivin showed poor prognosis. USP22 expression was well correlated with survivin expression in HCC cases. This correlation was confirmed in HCC cell lines and tissues by RT-PCR and western blot analysis. Next, to investigate the biological role of USP22 in HCC, we examined the effect of USP22 knockdown on the cell growth and the expression of cell cycle-related protein including survivin in HCC cells. USP22 siRNA suppressed cell growth. Moreover, USP22 siRNA decreased survivin expression together with upregulation of CDK inhibitor, p21 and downregulation of cyclinB. These findings suggest that USP22 may be involved in HCC progression in cooperation with survivin. We suggest that USP22 can be useful as a new prognostic marker and therapeutic target in HCC patients.

Samchuleum suppressed high glucose‐induced renal proliferation and fibrosis in cultured rat mesangial cells

Diabetic nephropathy associated with morbidity and mortality of diabetic patients. Mesangial cell proliferation is known as the major pathologic features such as glomerulosclerosis and renal fibrosis. Samchuleum (SCE), originally recorded in an ancient Korea medicinal book named “Donguibogam”, is a well‐known blended traditional herbal formula. Thus, this study was investigated the inhibitory effect of SCE (1‐50 μg/ml) on high glucose (HG)‐stimulated rat mesangial cells proliferation and fibrosis.Thymidine incorporation under HG was significantly accelerated, which was inhibited by SCE in a dose dependent manner. Pre‐treatment of SCE induced down‐regulation of cyclins/CDKs and up‐regulation of CDK inhibitor, p21waf1/cip1 and p27kip1 expression. In addition, SCE significantly suppressed the HG‐induced ROS production. Thus, SCE consequently inhibited HG‐induced mesangial cell proliferation through the inhibition of ROS signaling pathway.HG enhanced expression of fibrosis biomarkers such as collagen IV and CTGF, which was markedly attenuated by SCE. Moreover, SCE inhibits HG‐induced fibronectin mRNA expression. SCE decreased TGF‐β1 and p‐Smad2/Smad4 expression, whereas increased Smad7 expression under HG. Thus, SCE promoted ECM degradation through disturbing TGF‐β–SMAD signaling.In conclusion, these results suggested that SCE has a protective effect on renal proliferation and fibrosis. Thus SCE might prove to be effective in the treatment of renal dysfunction leading to Diabetic nephropathy.

오령산에 의한 고포도당 유도 사구체간질세포 이상증식 개선효과

Objectives : Diabetic nephropathy is associated with morbidity and mortality of diabetes mellitus patients. Mesangial cell proliferation is known as the major pathologic features such as glomerulosclerosis. Oryeong-san, Korean formula, is widely used for the treatment of nephrosis, edema, and uremia. Oryeong-san is composed of five herbs: Alismatis Rhizoma, Polyporus, Atractylodis Rhizoma Alba, Hoelen, and Cinnamomi Cortex. Methods : The present study was performed to investigate potent inhibitory effect of Oryeong-san on high glucose (HG)-induced rat mesangial cells (RMC) proliferation. Results : RMC proliferation under 25 mM glucose was significantly accelerated compared with 5.5 mM glucose, which was inhibited by Oryeong-san in dose dependent manner. Pre-treatment of Oryeong-san induced down-regulation of cyclins/CDKs and up-regulation of CDK inhibitor, p21waf1/cip1 and p27kip1 expression. In addition, Oryeong-san reduced HG-induced RMC proliferation by suppressed the mitogen-activated protein kinase (MAPK) phospholyration such as extracellular signal regulated kinase (ERK), Jun N-terminal Kinase (JNK), and p38. Oryeong-san significantly suppressed HG-induced ROS production. Conclusions : Oryeong-san consequently inhibited HG-induced mesangial cell proliferation through the inhibition of MAPK and ROS signaling pathway. These results suggest that Oryeong-san may be effective in the treatment of renal dysfunction leading to diabetic nephropathy.

Abstract 4860: Chemopreventive effects of α-santalol on ultraviolet B induced skin tumorigenesis by modulating cell cycle regulators.

Abstract Previous studies from our laboratory have shown chemopreventive effects of 5% α-santalol, a sequiterpene isolated from the sandalwood oil in ultraviolet-B induced skin tumor multiplicity in SKH-1 hairless mice. However, this dosage did not have significant effect on tumor incidence. The objective of this study was to investigate the effects of α-santalol (10%, w/v in acetone) on UVB-induced skin tumor incidence in SKH-1 hairless mouse model and to identify the molecular targets in α-santalol mediated protection. Tumor initiation and promotion were carried out by UVB radiation (30 mJ/cm2/day for 5 days a week up to 30 week) that is in the range of human exposure to sunlight that can cause skin cancer. Topical treatment of mice with α-santalol causes a significant reduction in tumor multiplicity, tumor volume and tumor incidence, and also delayed tumor development. Histopathological analysis of hematoxylin-eosin stained skin sections showed that α-santalol pretreatment strongly inhibited UVB-induced epidermal hyperplasia and total thickness of the epidermis. The proliferation potential of skin and tumor tissue sections from UVB-induced carcinogenesis protocol was evaluated by immunohistochemical expression of proliferation marker PCNA. Both intensity of brown staining as well as the number of positively stained nuclei were reduced in skin tumors and adjacent skin tissues from α-santalol treated group when compared to control group. Western blot analysis of skin lysates showed that α-santalol decreases the level of different cyclin-dependent kinases and associated cyclins, Cdc25 phosphatases (Cdc25B and Cdc25C) together with an up-regulation of CDK inhibitor Cip1/p21. However, the level of Kip1/p27 and p53 did not show a significant difference. Our data suggested that α-santalol (10%, topical) is a safer and promising skin cancer chemopreventive agent through targeting different cell cycle regulators. (This work is supported by a Translational Cancer Center Research Grant, funded by the State of South Dakota). Citation Format: Sreevidya Santha, Chandradhar Dwivedi. Chemopreventive effects of α-santalol on ultraviolet B induced skin tumorigenesis by modulating cell cycle regulators. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4860. doi:10.1158/1538-7445.AM2013-4860

Butyrate, an HDAC inhibitor, stimulates interplay between different posttranslational modifications of histone H3 and differently alters G1-specific cell cycle proteins in vascular smooth muscle cells

HDACs and HATs regulate histone acetylation, an epigenetic modification that controls chromatin structure and through it, gene expression. Butyrate, a dietary HDAC inhibitor, inhibits VSMC proliferation, a crucial factor in atherogenesis, and the principle mechanism in arterial and in-stent restenosis. Here, the link between antiproliferation action of butyrate and the portraits of global covalent modifications of histone H3 that it induces are characterized to understand the mechanics of butyrate-arrested VSMC proliferation. Analysis of histone H3 modifications specific to butyrate arrested VSMC proliferation display induction of histone H3-Lysine9 acetylation, inhibition of histone H3-Serine10 phosphorylation, reduction of histone H3-Lysine9 dimethylation and stimulation of histone H3-Lysine4 di-methylation, which is linked to transcriptional activation, cell cycle/mitosis, transcriptional suppression and activation, respectively. Conversely, untreated VSMCs exhibit inhibition of H3-Lysine9 acetylation, induction of H3-Serine10 phosphorylation, stimulation of H3-Lysine9 di-methylation and reduction in H3-Lysine4 di-methylation. Butyrate's cooperative effects on H3-Lysine9 acetylation and H3-Serine10 phosphorylation, and contrasting effects on di-methylation of H3-Lysine9 and H3-Lysine4 suggests that the interplay between these site-specific modifications cause distinct chromatin alterations that allow cyclin D1 and D3 induction, G1-specific cdk4, cdk6 and cdk2 downregulation, and upregulation of cdk inhibitors, p15INK4b and p21Cip1. Regardless of butyrate's effect on D-type cyclins, downregulation of G1-specific cdks and upregulation of cdk inhibitors by butyrate prevents cell cycle progression by failing to inactivate Rb. Overall, through chromatin remodeling, butyrate appears to differentially alter G1-specific cell cycle proteins to ensure proliferation arrest of VSMCs, a crucial cellular component of blood vessel wall.

Sulforaphane Switches Cyclin E Isoform Expression and Blocks Leukemic Cell Cycling.

Sulforaphane (SFN), an isothiocyanate derived from cruciferous vegetables, has been shown to inhibit the growth of prostate cancer cells in vitro and in vivo. We were interested in exploring potential antileukemic effects of SFN. The viability of multiple myeloid leukemic cell lines was decreased by 25uM SFN. Pharmacokinetic studies reported in rats suggest that this serum concentration can be achieved through oral dosing. Lower SFN concentrations (1–5 uM) inhibited leukemic cell growth without affecting cell viability. Synchronized HL-60 cells exposed to 25uM SFN were blocked at the G1/S phase transition. Kinetic analysis of cell cycle proteins demonstrated that the G1/S block arose from downmodulation of cyclins D3 and E rather than upregulation of cdk-inhibitors. Interestingly, we found that HL-60 cells expressed a low molecular weight (LMW, 36 kD) variant of cyclin E rather than (50 kD) full-length cyclin E. Treatment with SFN for as little as 2 hours caused a decrease in expression of the LMW cyclin E and induced the expression of a higher molecular weight (~50 kD) cyclin E isoform. Because LMW cyclin E has been associated with increased cdk2 activity and p27 resistance compared to full-length cyclin E, we postulate that SFN-mediated cyclin E isoform-switching contributed to growth inhibition of these leukemic cells. The signaling pathway through which SFN altered cyclin E expression appeared to be distinct from MEK/ERK and JNK pathways that have been implicated in the apoptotic effects of SFN. Given that cyclin E overexpression and, particularly, LMW cyclin E expression are correlated with poor prognosis in multiple cancers, the mechanism through which SFN decreases LMW cyclin E expression in these leukemic cells could have therapeutic significance.

β-Sitosterol에 의한 인체 대장암 HCT116 세포의 증식억제에 관한 연구

β-Sitosterol은 과일과 야채 등을 포함한 대부분의 고등식물에 존재하는 중요한 phytosterol의 하나로서, 인체 암의 예방과 치료에 매우 유효한 것으로 보고되어져 오고 있다. 본 연구에서는 β-sitosterol의 암세포 증식억제 기전의 해석을 시도하기 위하여 인체 대장암세포 HCT116의 증식에 미치는 β-sitosterol의 영향을 조사하였다. β-Sitosterol의 처리로 HCT116 암세포의 증식은 처리 농도 의존적으로 감소되었으며, 특히 7.5 μM 이상 처리에서는 급격한 성장억제 효과가 있었다. 또한 5.0 μM 처리군에서부터 apoptotic body의 형성이 관찰되었고, β-catenin 단백질의 분해 현상과 연관성이 있었다. 그리고 β-sitosterol이 처리된 암세포에서는 종양억제 유전자 p53 및 Cdk inhibitor p21의 발현이 전사 및 번역 수준에서 모두 증가되었다. 본 결과는 그동안 연구가 거의 진행되어져 있지 않았던 β-sitosterol에 의한 암세포주기 조절 해석을 위한 주요한 자료로 활용될 것이다.

Suppression of ARG kinase activity by STI571 induces cell cycle arrest through up-regulation of CDK inhibitor p18/INK4c.

ARG is a tyrosine kinase closely related to ABL, which is oncogenic when fused to the transcriptional repressor ETV6 (ETS translocation variant 6). In this study, we investigated the growth-inhibitory effect of STI571 (signal transduction inhibitor number 571) on ETV6/ARG-expressing cells and its molecular mechanisms using HT93A, a cell line derived from a patient with AML-M3 carrying t(1;12). STI571 effectively suppressed overall tyrosyl phosphorylation of intracellular proteins including ETV6/ARG fusion protein, as well as the growth of HT93A cells with an IC(50) of 200 nM. The growth inhibition was primarily because of cell cycle arrest at G1 phase when cells were treated with 100 nM STI571 for 48 h, and apoptosis was induced after longer exposure (72 h) or by a higher dose (1000 nM). STI571 increased the amount of p18/INK4c after 2 h of culture, when the cell cycle pattern was not yet affected, but not that of other CDK inhibitors (CKI). p18/INK4c was more abundant in G1-enriched fractions than in S- and G2/M-enriched fractions of STI571-treated HT93A cells, suggesting that the upregulation of p18/INK4c expression correlates with the cell cycle arrest. Treatment of HT93A cells with antisense oligonucleotides against the Ink4c gene abrogated the growth inhibition by STI571. These results suggest that leukemogenesis by an aberrant ARG kinase involves the suppression of p18/INK4c, which is ubiquitously expressed and considered the major CKI in hematopoietic stem cells. STI571 can be an effective drug for the treatment of leukemias with deregulated ARG kinase activity.

DNA replication and smooth muscle cell hypertrophy.

DNA replication and smooth muscle cell hypertrophy.

Transforming growth factor-beta1 up-regulates p15, p21 and p27 and blocks cell cycling in G1 in human prostate epithelium.

Transforming growth factor-beta1 (TGFbeta1) is inhibitory to most epithelia, but its role in the control of proliferation of prostatic epithelium is unclear. In some cells, TGFbeta1 inhibition is achieved by up-regulation of cyclin-dependent kinase (cdk) inhibitors including p15, p21 and p27. Our aims were to determine whether the effects of TGFbeta1 on human prostatic epithelial cell cycle kinetics were mediated by alterations in the levels of the cdk inhibitors p15, p16, p21 and p27 and hypo-phosphorylated retinoblastoma protein (Rb). Human prostatic epithelial cells in primary culture were grown in the presence of TGFbeta1 (0-10 ng/ml) for up to 4 days and proliferation assessed using a [3H]thymidine uptake assay. Levels of p15, p16, p21 and p27 were measured at both mRNA and protein level by means of a reverse transcriptase PCR-based assay and Western analysis. Rb and cdk2 levels were measured. Exogenous TGFbeta1 (0-5 ng/ml) inhibited proliferation. This was associated with blocking of the cell cycle at G1, and up to 4-fold increases in p15, p21 and p27 mRNA levels, but no change was observed in p16 mRNA levels; these changes were not blocked by cycloheximide. Increased levels of p15, p21 and p27 protein were also accompanied by increased levels of hypo-phosphorylated Rb and decreased cdk2 kinase activity. TGFbeta1 has mainly inhibitory effects on benign human prostatic epithelium, which are caused by up-regulation of cdk inhibitors, hypo-phosphorylation of Rb and delaying of the cell cycle in G1.