Growth Arrest In Cancer Cells Research Articles

Growth arrest and apoptosis induction in androgen receptor-positive human breast cancer cells by inhibition of USP14-mediated androgen receptor deubiquitination

It has been well known that androgen receptor (AR) is critical to prostate cancer development and progression. It has also been documented that AR is expressed in more than 60% of breast tumors, which promotes the growth of estrogen receptor-negative (ER–)/AR-positive (AR+) breast cancer cells. Thus, AR might be a potential therapeutic target for AR-positive/ER-negative breast cancer patients. Previously we reported that in prostate cancer cells proteasome-associated deubiquitinase ubiquitin-specific protease 14 (USP14) stabilized AR protein level by removing its ubiquitin chain. In the current study, we studied the USP14-AR protein interaction and cell proliferation status after USP14 reduction or inhibition in breast cancer cells, and our results support the conclusion that targeting USP14 is a novel strategy for treating AR-responsive breast cancer. We found that inhibition of USP14 accelerated the K48-ubiquitination and proteasome-mediated degradation of AR protein. Additionally, both genetic and pharmacological inhibition of USP14 significantly suppressed cell proliferation in AR-responsive breast cancer cells by blocking G0/G1 to S phase transition and inducing apoptosis. Moreover, AR overexpression inhibited USP14 inhibition-induced events, suggesting that AR deubiquitination by USP14 is critical for breast cancer growth and USP14 inhibition is a possible strategy to treat AR-positive breast cancer.

Nutlin-3, A p53-Mdm2 Antagonist for Nasopharyngeal Carcinoma Treatment.

Nasopharyngeal carcinoma (NPC) is a form of head and neck cancer of multifactorial etiolo-gies that is highly prevalent among men in the population of Southern China and Southeast Asia. NPC has claimed many thousands of lives worldwide; but the low awareness of NPC remains a hindrance in early diagnosis and prevention of the disease. NPC is highly responsive to radiotherapy and chemothera-py, but radiocurable NPC is still dependent on concurrent treatment of megavoltage radiotherapy with chemotherapy. Despite a significant reduction in loco-regional and distant metastases, radiotherapy alone has failed to provide a significant improvement in the overall survival rate of NPC, compared to chemo-therapy. In addition, chemo-resistance persists as the major challenge in the management of metastatic NPC although the survival rate of advanced metastatic NPC has significantly improved with the admin-istration of chemotherapy adjunctive to radiotherapy. In this regard, targeted molecular therapy could be explored for the discovery of alternative NPC therapies. Nutlin-3, a small molecule inhibitor that specifi-cally targets p53-Mdm2 interaction offers new therapeutic opportunities by enhancing cancer cell growth arrest and apoptosis through the restoration of the p53-mediated tumor suppression pathway while pro-ducing minimal cytotoxicity and side effects. This review discusses the potential use of Nutlin-3 as a p53-activating drug and the future directions of its clinical research for NPC treatment.

Administering xCT Inhibitors Based on Circadian Clock Improves Antitumor Effects.

Clock genes encoding transcription factors that regulate circadian rhythms may inform chronomodulated chemotherapy, where time-dependent dose alterations might affect drug efficacy and reduce side effects. For example, inhibiting the essential cystine transporter xCT with sulfasalazine induces growth arrest in cancer cells. Although the anticancer effects of sulfasalazine have been studied extensively, its effects on transcriptional control of xCT expression have not been studied. Here, we show that sulfasalazine administration during the period of increased xCT expression improves its anticancer effects and that the Clock gene itself induces xCT expression and regulates its circadian rhythm. Our findings highlight the clinical potential of chronomodulated chemotherapy and the importance of xCT-mediated transcriptional regulation in the utility of such strategies. Cancer Res; 77(23); 6603-13. ©2017 AACR.

A Simple Method to Optimize the Effectiveness of Chemotherapy: Modulation of Glucose Intake During Chemotherapy.

Cancer cells consume high amounts of glucose to produce ATP and molecules entering biosynthesis. Numerous experimental studies have demonstrated that glucose deprivation and/or glycolysis inhibition arrest cancer cell growth and may increase the efficiency of cytotoxic drugs. In contrast, increasing glycolysis in tumor-infiltrating lymphocytes (TILs) activates these cells that destroy cancer cells. We propose to increase the efficiency of chemotherapy by modulating glucose intake during the course of chemotherapy. Glucose and caloric intake should be drastically reduced the day before and during chemotherapy administration to deprive cancer cells of ATP and molecules required to repair cytotoxic lesions. Few hours after chemotherapy, glucose and caloric intake should be drastically increased for few days to promote the activation of TILs that reinforce the destruction of cancer cells. This strategy could improve the results of chemotherapy by first enhancing cytotoxic stress against tumor cells and then promoting activation of the anti-cancer immune response. The modulation of glucose intake during chemotherapy should be tested clinically. The proposed scheme is simple, surely easier to follow than a strict chronic diet, and should avoid weight loss.

Abstract B38: Exploring targeting potassium channels in cancer: A novel strategy for therapeutic intervention

Abstract Failing of anticancer therapies is mostly due to our limited understanding of biochemical signaling in cancer cells. Therefore, identification of new targets and new strategies for anticancer drug discovery is greatly needed. Potassium ion (K+) channels are transmembrane associated proteins that control several biological processes including cell proliferation and cell motility in both physiological and pathological conditions by allowing an outward flux of K+ ion to cross the surface membrane. Furthermore, several K+ ion channels have been found expressed in cancers of different histogenesis but not in tissues from which cancer has been generated. This suggests that changes in K+ ion gradients play a key role in cancer biology. In contrast to blockers, K+ channels activators are well tolerated in mammals and several FDA approved K+ channels activators are readily available on the market suggesting that these agents could be used as potential anticancer drug. Nevertheless, very little has been done to understand whether these proteins can be used as therapeutic targets against cancers. We present data showing for the first time that pharmacologic stimulation of specific K+ channels with small molecules strongly reduced tumor growth and metastatic spread in different animal model of cancer biology including Drosophila and mice without discernible side effects. For example, use of two chemically distinct Kv11.1 potassium channel activators showed growth arrest in an in vivo Drosophila tumor model and strongly inhibited tumor growth in SCID mice bearing the aggressive TNBC cell line MDA-MB-231. In addition, the metastatic spread of this cancer cell line in NOD-scid-IL2Rγnull was significantly reduced in terms of organs affected and metastatic burden. Interestingly, analysis of the biochemical signaling linking activation of specific K+ channels to tumor growth inhibition revealed that pharmacological stimulation of K+ channel activated a cellular senescent program that is characterized by increased expression of the tumor suppressors (e.g. p21, p16, HMGA2), formation of heterochromatin and permanent growth arrest of cancer cells independently of their molecular subtypes (including p53 negative cancer cells, breast, skin or ovarian cancer cells). Investigating on the possible mechanism linking Kv11.1 stimulation to inhibition of metastasis revealed that Kv11.1 agonists strongly inhibit cancer cell motility by suppressing nuclear function of bβ-catenin in transcribing for Epithelial to Mesenchymal Transition (EMT) markers including vimentin, CD44, N-cadherin. Concurrently, K+ channel agonists increased cytoplasmic β-catenin protein level by repressing its degradation, increased levels of the adhesive molecule E-cadherin and promoted formation of the proteins complex bβ-catenin/E-cadherin at the surface membrane. Overall, our data strongly suggest that use of K+ channel agonists can inhibit tumor progression by activating senescence and inhibit metastasis by reversing mesenchymal into epithelial phenotype (MET). We think that these are important discoveries because they offer an opportunity to identify in K+ channels proteins that can be therapeutically targeted to eliminate tumor growth and metastasis. Citation Format: Eun-Kyoung Breuer, Clodia Osipo, Jeremiah Zartman, Claire Wells, Michael Nishimura, Walter Jones, Saverio Gentile. Exploring targeting potassium channels in cancer: A novel strategy for therapeutic intervention [abstract]. In: Proceedings of the AACR Precision Medicine Series: Opportunities and Challenges of Exploiting Synthetic Lethality in Cancer; Jan 4-7, 2017; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2017;16(10 Suppl):Abstract nr B38.

Down regulation of the long non-coding RNA PCAT-1 induced growth arrest and apoptosis of colorectal cancer cells

AimsThe long non-coding RNA (lncRNA) was reported to be involved in the progress of various cancers, however, its effect in colorectal cancer (CRC) remains unknown. The goal of the present study is to investigate the function role of lncRNA PCAT-1 in colorectal cancer. Main methodsThe expression of lncRNA PCAT-1 in four CRC cell lines was measured by real-time PCR, and two lncRNA PCAT-1 high expression cell lines were selected. LncRNA PCAT-1 in these two CRC cell lines was down-regulated by shRNA, and the stable transfected cells were established. Functional involvement of lncRNA PCAT-1 in proliferation and apoptosis of the two CRC cells were evaluated in vitro. Mover, the effect of lncRNA PCAT-1 in tumor proliferation was also evaluated in CRC cell xenograft. Key findingsThe results showed that down-regulation of lncRNA PCAT-1 in CRC cells inhibited proliferation, blocked cell cycle transition, and suppressed the expression of cyclins and c-myc. The apoptosis cell proportion was elevated with increased expression of pro-apoptotic proteins and decreased anti-apoptotic proteins in lncRNA PCAT-1 knock down cells. Forced over-expression of c-myc in PCAT-1 down-regulated CRC cells increased the level of cyclins. The xenograft growth in lncRNA PCAT-1 down-regulated cells was significantly inhibited along with the reduced proliferative cells. SignificanceOur study revealed a tumorigenic effect of lncRNA PCAT-1 in CRC cells, and this effect is partly dependent on the inhibition of c-myc.

Significance of the TMPRSS2:ERG gene fusion in prostate cancer.

The transmembrane protease serine 2:v-ets erythroblastosis virus E26 oncogene homolog (TMPRSS2:ERG) gene fusion is common in prostate cancer, while its functional role is not fully understood. The present study aimed to investigate the significance of the TMPRSS2:ERG gene fusion in human prostate cancers using bioinformatics tools. Comprehensive alteration analysis of TMPRSS2 and ERG in 148 different human cancer studies was performed by cBioPortal, and the mRNA expression level of the ERG gene was evaluated using Oncomine analysis. Furthermore, lentiviral short hairpin (sh)RNA-mediated knockdown of TMPRSS2:ERG was performed to study the impact of ERG silencing on cell proliferation and cell cycle distribution in prostate cancer cells. The results demonstrated that the TMPRSS2 and ERG genes were mostly altered in prostate cancer, and the most frequent alteration was gene fusion. Oncomine analysis demonstrated that the ERG gene was significantly upregulated in prostate clinical samples compared with the normal prostate gland in four independent datasets, and a positive association was observed between potassium inwardly-rectifying channel subfamily J member 15, down syndrome critical region gene 4, potassium inwardly-rectifying channel subfamily J member 6 and ERG gene expression. There were 272 mutations of the ERG gene identified in the cBioPortal database; among the mutations, 2 missense mutations (R367C and P401H) were regarded as functional mutations (functional impact score >1.938). Furthermore, the present study successfully knocked down ERG gene expression through a lentiviral-mediated gene silencing approach in VCaP prostate cancer cells. The ERG mRNA and protein expression levels were both suppressed significantly, and a cell-cycle arrest at G0/G1 phase was observed after ERG gene silencing. In conclusion, these bioinformatics analyses provide novel insights for TMPRSS2:ERG fusion gene study in prostate cancer. Target inhibition of ERG expression could significantly cause cell growth arrest in prostate cancer cells, which could be a potentially valuable target for prostate cancer treatment. However, the precise mechanism of these results remains unclear; therefore, further studies are required.

Induction of senescence in cancer cells by 5′-Aza-2′-deoxycytidine: Bioinformatics and experimental insights to its targets

5′-Aza-2′-deoxycytidine (5-Aza-dC) is a demethylating drug that causes genome-wide hypomethylation resulting in the expression of several tumor suppressor genes causing growth arrest of cancer cells. Cancer is well established as a multifactorial disease and requires multi-module therapeutics. Search for new drugs and their approval by FDA takes a long time. Keeping this in view, research on new functions of FDA-approved anticancer drugs is desired to expand the list of multi-module functioning drugs for cancer therapy. In this study, we conducted an analysis for new functions of 5-Aza-dC by applying bio-chemo-informatics approach. The potential of 5-Aza-dC bioactivity was analyzed by PASS online and Molinspiration. Target proteins were predicted by SuperPred. The protein networks and biological processes were analyzed by Biological Networks using Gene Ontology tool, BINGO, based on BIOGRID database. Interactions between 5-Aza-dC and targeted proteins were examined by Autodoc Vina integrated into pyrx software. Induction of p53 by 5-Aza-dC was tested in vitro using cancer cells. Bioinformatics analyses predicted that 5-Aza-dC functions as a p53 inducer, radiosensitizer, and inhibitor of some enzymes. It was predicted to target proteins including MDM2, POLA1, POLB, and CXCR4 that are involved in the induction of DNA damage response and p53-HDM2-p21 signaling. In this study, we provide experimental evidence showing HDM2 is one of the targets of 5-AZA-dC leading to activation of p53 pathway and growth arrest of cells. Furthermore, we found that the combinatorial treatment of 5-AZA-dC with three other drugs caused drug resistance. We discuss that 5-Aza-dC-induced senescence is a multi-module drug that controls cell proliferation phenotype not only by proteins but also by noncoding miRNAs. Further studies are warranted to dissect these mechanisms and establish 5-Aza-dC as an effective multi-module anticancer reagent.

Long Noncoding RNA GAS5 Suppresses Tumorigenesis by Inhibiting miR-23a Expression in Non-Small Cell Lung Cancer.

Previous studies reported that elevated expression of long noncoding RNA (lncRNA) GAS5 led to the arrest of non-small cell lung cancer (NSCLC) cell growth and a promotion of apoptosis both in vitro and in vivo. However, its underlying molecular mechanism in NSCLC is still unclear. In the present study, we noted that GAS5 was downregulated in NSCLC tissues and cells and was negatively correlated with miR-23a expression. Luciferase reporter assay and qRT-PCR analysis demonstrated that GAS5 directly interacted with miR-23a and reversely regulated its expression. miR-23a overexpression markedly promoted NSCLC cell proliferation and invasion, while GAS5 overexpression dramatically inhibited NSCLC cell proliferation and invasion and promoted apoptosis. Functional analysis indicated that miR-23a overexpression significantly abolished GAS5 overexpression-induced inhibition of proliferation and invasion, as well as promotion of apoptosis in NSCLC cells. Moreover, xenograft experiments further revealed that upregulation of GAS5 notably impaired the growth of transplanted tumors by suppressing miR-23a in nude mice. These results suggested that overexpression of lncRNA GAS5 inhibits tumorigenesis of NSCLC by inhibiting miR-23a in vitro and in vivo, providing a potential therapeutic strategy for patients with NSCLC.

Abstract 1387: Target RNA sequencing revealed the expression profile of cancer genes in response to deacetylase inhibitor in primary culture of prostate cancer cells

Abstract Histone acetylation is a dynamic event to optimize cell functions through the control of RNA transcription and gene expression. In cancer, the histone deacetylation is a therapeutic target. Suppression of histone deacetylase increased the growth arrest, apoptosis, and senescence in cancer cells. Several histone deacetylase inhibitors (HDACis) have been developed and applied as a target therapy of various types of cancer, including the prostate cancer. However, the altered gene expression in HDACis treated prostate cancer cells is less reported. Little is known about the gene expression profiles of primary cultures of prostate cancer. In this study, we examined the cancer gene expression profile in primary cultures of human prostate cancer. Cells were isolated from two patient’s prostate cancer samples. Isolated cells were cultured in prostate epithelium culture medium CnT-52. After 24 hours of exposure to 400nM of Trichostatin A (TSA), an inhibitor of histone deacetylase I and II. RNA was extracted and quantified. The library was prepared with Illumina’s TruSight RNA Pan-Cancer Panel. The sequencing was performed on NextSeq 500 platform with NextSeq 500/550 mid output v2 kit (150cycles). FastQ files were generated by BaseSpace Onsite and analyzed further by TopHat alignment (Illumina) and Partek Flow (Partek). The Trusight RNA Pan-Cancer panel targets 1385 cancer genes and covers 21043 exonic regions with 57010 probes. The results showed that 59 of the 1385 cancer genes were significantly changed (FDR p-value<0.05, fold change >4 fold) in TAS treated cells. In the treated cells 49 genes were unregulated and 10 genes were down-regulated. The altered expression of 59 genes is involved in multiple cell functions. Genes that were upregulated included apoptosis associated genes (MAP2K6 and BIRC3), tumor suppression genes (DIRAS3, PEG3, PTPRO, and DNM3), and P53-target gene (CYFIP2). The genes that were down-regulated included cell cycle regulation genes (CDK1 and CCNA2), DNA damage response genes (BRCA1 and BRIP1), as well as cell proliferation marker Ki67 gene (MKI67). However, the gene expression response to TSA is complicated. Some altered gene expression favors tumor growth and progression while other gene expression changes inhibit tumor growth and promote apoptosis. In conclusion, we identified the gene profile in primary culture of prostate tumor in response to a histone deacetylase inhibitor, TSA. The therapeutic effects of HDACis could be influenced by the summation of contradicting tumor promoting and suppression gene expression profile changes. Citation Format: Hong Yin, Adam H. Greer, Glenn Mills. Target RNA sequencing revealed the expression profile of cancer genes in response to deacetylase inhibitor in primary culture of prostate cancer cells [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 1387. doi:10.1158/1538-7445.AM2017-1387

Abstract 310: Enhanced stability of D-type cyclins correlates with glioblastoma resistance to ionizing radiation

Abstract Transition from G1 to S phase of the cell cycle is promoted by D-type cyclins (D1, D2 and D3), regulatory subunits critical for the activation of cyclin dependent kinases 4 and 6 (CDK4/6), which phosphorylate and inactivate the retinoblastoma protein (pRb) and activate the transcription factor E2F1 to promote the expression of genes essential for DNA synthesis. Deregulated expression of D-type cyclins is frequently observed in human malignancies and correlates with increased proliferation. Cyclin Ds overexpression is also associated with radioresistance, leading to radiotherapy failure and disease recurrence. Cyclin D1 undergoes ubiquitin-dependent degradation following the exposure of cancer cells to ionizing radiation (IR), and this has been shown to be critical for IR-induced G1 growth arrest and sensitivity of cancer cells to IR. While the role of cyclin D1 overexpression in drug resistance is already well documented, less is known about the role of cyclins D2 and D3 in radio-resistance in human cancer cells, particularly in brain neoplasms. In the present study, we investigated the effect of IR on different D-type cyclins (D1, D2, D3) in human glioblastoma cell lines as well as in tumor-derived mouse oligodendrocytes progenitor cells (OPCs). Here, we show that exposure of human astrocytes to increasing levels of IR led to a rapid proteasomal degradation of all three D-type cyclins. On the other hand, IR failed to induce significant cyclin Ds degradation in a number of human glioblastoma cells (U87, A172, U251, Snb19). Analysis of cell cycle profile of all glioblastoma cells tested and exposed to IR showed prominent cell cycle arrest in G1 starting at 24 hours following exposure. Furthermore, we show that the steady-state levels of D-type cyclin is higher in OPCs compared to mouse NIH3T3 cells and fail to undergo proteasomal degradation following IR exposure. Collectively, these results suggest that the degradation of D-type cyclins is not critical for IR-induced G1 cell cycle arrest in GMB and may underlie their resistance to IR. Understanding the role of cyclin Ds in promoting radioresistance may lead to a useful pharmacological strategy to enhance radiotherapy outcome and help implement a more effective treatment modality. Citation Format: Fadila Guessous, Mouadh Benamar, Hui Zhong, Tarek Abbas. Enhanced stability of D-type cyclins correlates with glioblastoma resistance to ionizing radiation [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 310. doi:10.1158/1538-7445.AM2017-310

Metformin Synergistically Potentiates the Antitumor Effects of Imatinib in Colorectal Cancer Cells.

ABSTRACTMetformin is the most commonly prescribed anti-diabetic drug with relatively minor side effect. Substantial evidence has suggested that metformin is associated with decreased cancer risk and anticancer activity against diverse cancer cells. The tyrosine kinase inhibitor imatinib has shown powerful activity for treatment of chronic myeloid leukemia and also induces growth arrest and apoptosis in colorectal cancer cells. In this study, we tested the combination of imatinib and metformin against HCT15 colorectal cancer cells for effects on cell viability, cell cycle and autophagy. Our data show that metformin synergistically enhances the imatinib cytotoxicity in HCT15 cells as indicated by combination and drug reduction indices. We also demonstrate that the combination causes synergistic down-regulation of pERK, cell cycle arrest in S and G2/M phases via reduction of cyclin B1 level. Moreover, the combination resulted in autophagy induction as revealed by increased acidic vesicular organelles and cleaved form of LC3-II. Inhibition of autophagic process by chloroquine led to decreased cell viability, suggesting that induction of autophagy seems to play a cell protective role that may act against anticancer effects. In conclusion, our present data suggest that metformin in combination with imatinib might be a promising therapeutic option in colorectal cancer.

Butyrate induces ROS-mediated apoptosis by modulating miR-22/SIRT-1 pathway in hepatic cancer cells

Butyrate is one of the short chain fatty acids, produced by the gut microbiota during anaerobic fermentation of dietary fibres. It has been shown that it can inhibit tumor progression via suppressing histone deacetylase and can induce apoptosis in cancer cells. However, the comprehensive pathway by which butyrate mediates apoptosis and growth arrest in cancer cells still remains unclear. In this study, the role of miR-22 in butyrate-mediated ROS release and induction of apoptosis was determined in hepatic cells. Intracellular expression of miR-22 was increased when the Huh 7 cells were incubated with sodium butyrate. Over-expression of miR-22 or addition of sodium butyrate inhibited SIRT-1 expression and enhanced the ROS production. Incubation of cells with anti-miR-22 reversed the effects of butyrate. Butyrate induced apoptosis via ROS production, cytochrome c release and activation of caspase-3, whereas addition of N-acetyl cysteine or anti-miR-22 reversed these butyrate-induced effects. Furthermore, sodium butyrate inhibited cell growth and proliferation, whereas anti-miR-22 inhibited these butyrate-mediated changes. The expression of PTEN and gsk-3 was found to be increased while p-akt and β-catenin expression was decreased significantly by butyrate. These data showed that butyrate modulated both apoptosis and proliferation via miR-22 expression in hepatic cells.

MiR-940 upregulation contributes to human cervical cancer progression through p27 and PTEN inhibition.

Cervical cancer is considered as a gynecological malignancy accompanied with high rates of mortality across the world. Effective diagnostic, prognostic markers as well as therapeutic targets are necessary to be explored. The p27 and PTEN are known to modulate tumor cell growth and proliferation. However, the molecular mechanisms modulating these genes have not completely been elucidated. In our study, real-time (RT) quantitative PCR indicated that miR‑940 levels were upregulated in human cervical cancer tissue samples and cell lines. Overexpression of miR‑940 could reduce overall survival in patients. Ectopic miR‑940 accelerated cervical cancer cell growth, proliferation and cell cycle arrest invitro as well as tumor formation invivo. p27 and PTEN were evidenced as direct targets for miR‑940 and inhibition of p27 and PTEN recovered the suppressive function of miR‑940-silenced cell towards to proliferation and tumorigenicity in cervical cancer cells. In addition, miR‑940 expression was inversely associated with p27 and PTEN expression levels and actively with cyclinD1 in cervical cancer specimens. The results from our study demonstrated that miR‑940 regulated p27 and PTEN post-transcriptionally and might play a significant role in cervical cancer development and progression. Thus, miR‑940 might provide a potential value as therapeutic target for cervical cancer treatment in future.

Tetrahydroporphyrin-tetratosylat (THPTS): A near-infrared photosensitizer for targeted and efficient photodynamic therapy (PDT) of human bladder carcinoma. An in vitro study

BackgroundEfficacy of PDT in muscle-invasive bladder cancer is hampered by low tissue penetration of most photosensitizers by short excitation wavelength. THPTS is excitable at near-infrared (760nm) allowing tissue penetration up to 15mm. We examined the cellular effects of THPTS-PDT in human bladder cancer cells. Material and methodsWe used four human transitional carcinoma cell lines, epithelial bladder progenitors (HBLAK) and bladder smooth muscle cells (HBSMC). We used flow cytometry to examine pharmacokinetics of THPTS, confocal laser scanning microscopy to analyze subcellular localization and production of reactive oxidative species (ROS), examined cytotoxicity and cell death pathways (qRT-PCR). ResultsTotal uptake varied between cell lines and was significantly high in HBLAK and HBSMC. Lysosomal localization was mainly seen in cancer cells and HBLAK, while THPTS was distributed throughout the cytoplasm in HBSMC. Significant ROS production was detected 30min after THPTS-PDT. Growth arrest occurred within 4h and resulted in apoptotic and necrotic cytotoxicity after 24h. Cytotoxicity was dose-dependent and specifically high in cancer cells and HBLAK and significantly low in HBSMC. ConclusionTHPTS-PDT induces cellular mechanisms leading to cellular growth arrest, apoptosis and necrosis in human bladder cancer cells. These effects are only partly dependent on the total amount of THPTS uptake and rather dependent on its subcellular compartmentalization. HBSMC are hardly affected by THPTS-PDT confirming tumor specificity and safety. THPTS is a promising new photosensitizer with the unique advantage of deep tissue penetration allowing the treatment of solid tumors and warranting further animal studies.

Original research paper. Hydrazinyldiene-chroman-2,4-diones in inducing growth arrest and apoptosis in breast cancer cells: Synergism with doxorubicin and correlation with physicochemical properties.

This study evaluates the effects of previously synthesized hydrazinyldiene-chroman-2,4-diones on cell proliferation and apoptosis, cell cycle distribution and migration capacity of MCF-7 breast cancer cells in synergy with doxorubicin. Physicochemical properties of the synthesized compounds were correlated with their structure and activity. Significant cell viability decrease in comparison with the effect of doxorubicin alone and the reference 4-hydroxycoumarin was observed when combination treatment comprising doxorubicin and the title compounds was applied. Synergistic effect with doxorubicin was also observed in down-regulation of phospho-Thr308Akt levels, confirming reduced proliferation and increased apoptosis. Combined treatment increased the percentage of cells arrested at the G2/M stage. Additive inhibition of cell migration was also observed, pointing to the possibility of reducing the risk of metastases. With their solubility profile and log D7.4, all the synthesized compounds follow Lipinski's rule of five for good permeability (absorption) potential.

UHRF1: The key regulator of epigenetics and molecular target for cancer therapeutics.

UHRF1 is a master regulator of epigenome as it coordinates DNA methylation and histone modifications. Compelling evidence suggests a strong link between UHRF1 overexpression and tumorigenesis, substantiating its ability to act as a potential biomarker for cancer diagnosis and prognosis. UHRF1 also mediates repair of damaged DNA that makes cancer cells resistant toward cytocidal drugs. Hence, understanding the molecular mechanism of UHRF1 regulation would help in developing cancer therapeutics. Natural compounds have shown applicability to downregulate UHRF1 leading to growth arrest and apoptosis in cancer cells.

Chidamide Inhibits Aerobic Metabolism to Induce Pancreatic Cancer Cell Growth Arrest by Promoting Mcl-1 Degradation.

Pancreatic cancer is a fatal malignancy worldwide and urgently requires valid therapies. Previous research showed that the HDAC inhibitor chidamide is a promising anti-cancer agent in pancreatic cancer cell lines. In this study, we elucidate a probable underlying anti-cancer mechanism of chidamide involving the degradation of Mcl-1. Mcl-1 is frequently upregulated in human cancers, which has been demonstrated to participate in oxidative phosphorylation, in addition to its anti-apoptotic actions as a Bcl-2 family member. The pancreatic cancer cell lines BxPC-3 and PANC-1 were treated with chidamide, resulting in Mcl-1 degradation accompanied by induction of Mcl-1 ubiquitination. Treatment with MG132, a proteasome inhibitor reduced Mcl-1 degradation stimulated by chidamide. Chidamide decreased O2 consumption and ATP production to inhibit aerobic metabolism in both pancreatic cancer cell lines and primary cells, similar to knockdown of Mcl-1, while overexpression of Mcl-1 in pancreatic cancer cells could restore the aerobic metabolism inhibited by chidamide. Furthermore, chidamide treatment or Mcl-1 knockdown significantly induced cell growth arrest in pancreatic cancer cell lines and primary cells, and Mcl-1 overexpression could reduce this cell growth inhibition. In conclusion, our results suggest that chidamide promotes Mcl-1 degradation through the ubiquitin-proteasome pathway, suppressing the maintenance of mitochondrial aerobic respiration by Mcl-1, and resulting in inhibition of pancreatic cancer cell proliferation. Our work supports the claim that chidamide has therapeutic potential for pancreatic cancer treatment.

FK228 augmented temozolomide sensitivity in human glioma cells by blocking PI3K/AKT/mTOR signal pathways

Temozolomide is a novel cytotoxic agent currently used as first-line chemotherapy for glioblastoma multiforme (GBM). Romidepsin (FK228), a histone deacetylase inhibitor, is a promising new class of antineoplastic agent with the capacity to induce growth arrest and/or apoptosis of cancer cells. However, combination of the two drugs in glioma remains largely unknown. In the present study, we evaluated the combinatory effects of FK228 with TMZ in glioma, and its molecular mechanisms responsible for these effects. Glioma cell lines were treated with TMZ, FK228 or the combination of drugs. The resistance effect including cytotoxicity and apoptosis was determined in glioma cells, respectively. We further evaluated the effects of FK228 in the PI3K/Akt-signaling pathway in vitro. Mice engrafted with 5×106 LN382 cells were treated with TMZ, FK228 or the combination of two drugs, and tumor weights and volumes were measured, respectively. FK228 enhanced the cytotoxic effects of TMZ in glioma cells compared to vehicle-treated controls or each drug alone. The combination of FK228 and TMZ-induced apoptosis was demonstrated by increased expression of cleaved-Caspase 3, Bax, cleaved-PARP, and decreased Bcl-2 expression. Furthermore, the expression of key components of the PI3K/Akt-signaling pathway showed that combination of FK228 and TMZ block PI3K/Akt pathways in vitro. This block effect was also confirmed in vivo in mice models. Mice treated with both FK228 and TMZ drugs showed significantly reduced tumor weights and volumes, compared to each drug alone. Our results suggested that FK228 augmented temozolomide sensitivity in human glioma cells partially by blocking PI3K/AKT/mTOR signal pathways. It thus may provide a promising target for improving the therapeutic outcome of TMZ-resistant gliomas, although further studies will be needed.

Abstract 3547: CEBPD induces apoptosis through autophagy in metformin-treated HCC

Abstract The patients with hepatocellular carcinoma (HCC) face the risk of cancer relapse or liver dysfunction. Metformin (Met), a first-line drug of type 2 diabetes, has been proved that it could induce G1 arrest and prevent or inhibit HCC. Previously, we demonstrated that the transcription factor CCAAT/enhancer-binding protein delta (CEBPD) plays a tumor suppressor and is responsive to many anticancer drugs in HCC. In this study, we found that Met could induce autophagy, growth arrest and further apoptosis in Huh7 cells. Met enhanced CEBPD expression via stabilizing its protein stability. The loss of CEBPD attenuated the Met-induced autophagy, growth arrest and apoptosis. Importantly, in addition to increasing P27 and down-regulating cyclin D1, CEBPD also contributed the increases of LC3B and ATG3 and LC3 puncta formation. We revealed a novel involvement of CEBPD in Met-induced growth arrest, apoptosis and autophagy of liver cancer cells through regulating p27, cyclinD1, LC3B and ATG3. Citation Format: I P. Lin. CEBPD induces apoptosis through autophagy in metformin-treated HCC. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3547.