bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 3758: Inhibition of ATR, but not ATM, sensitizes gynecologic cancer cells to cisplatin
Authors: Teng Pang-Ning , Bateman Nicholas W. , Hamilton Chad A. , Maxwell G. Larry , Bakkenist Christopher J. , Conrads Thomas P.
Published: May 2015

Resistance to platinum-based therapies remains a major hurdle in the management of gynecologic (GYN) cancer especially in ovarian cancer. Platinum such as cisplatin damages DNA by inducing DNA crosslinks that stalls DNA replication forks where significant accumulation of single-stranded DNA from persistently stalled replication forks could ultimately lead to double strand breaks and activation of apoptosis. Ataxia telangiectasia mutated (ATM) and ATM and Rad-3-related (ATR) are two main DNA damage response (DDR) protein kinases that recognize genotoxic stress and function to initiate cell cycle arrest and DNA repair mechanisms. We hypothesized by combining genotoxic stress with inhibition of DDR kinases ATR and/or ATM, therapeutic response of GYN cancer cells to platinum-based chemotherapy could be improved. To test our hypothesis, we assessed cell survival of multiple GYN cell lines including ovarian (A2780, A2780-CP20, OVCAR3), endometrial (KLE, HEC1B), and cervical (HELA, SIHA) carcinoma cells exposed to cisplatin along with ATR inhibitor (ETP-46464) and/or ATM inhibitor (KU55933). We observed inhibition of ATR significantly enhanced cisplatin induced cell death in all seven cell lines tested, resulting in 65 - 96% increased sensitivity to cisplatin. Inhibition of ATM did not sensitize GYN cancer cells to cisplatin and cells were not further sensitized by co-inhibition of ATM and ATR beyond that observed by inhibition of ATR alone. DDR signaling was assessed by immunoblotting in cells exposed to cisplatin with or without the presence of ETP-46464 and/or KU55933 where elevated levels of phospho-ATM (Ser1981), phospho-Chk2 (Thr68) and phospho-Chk1 (Ser345) observed in cisplatin treated cells were attenuated in cells that were co-treated with cisplatin and ETP-46464. In addition, increased levels of cleaved PARP1 and caspase 3 were observed in cisplatin-treated, ATR-inhibited cells, suggesting the enhancement of cisplatin induced cell death with ATR inhibition occurs through elevated apoptosis. Further, no differential effect was observed in GYN cancer cells harboring wild type (A2780, OVCAR3, HELA, SIHA) or mutant (CP20, KLE, HEC1B) TP53. These data support further investigation of pharmacologic inhibitors of ATR in combination with existing platinum based therapeutics for treating GYN cancer.

Citation Format: Pang-Ning Teng, Nicholas W. Bateman, Chad A. Hamilton, G. Larry Maxwell, Christopher J. Bakkenist, Thomas P. Conrads. Inhibition of ATR, but not ATM, sensitizes gynecologic cancer cells to cisplatin. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3758. doi:10.1158/1538-7445.AM2014-3758
Abstract 3759: Identification of novel carboplatin resistance gene in ovarian cancer
Authors: Wei Han , She Yun , Lu Tao
Published: May 2015

Ovarian cancer (OC) is the most lethal gynecology cancer in the world. Although carboplatin is one of the major drugs used to treat OC, resistance to carboplatin remains a major barrier to successful treatment. To date, the mechanisms of carboplatin resistance are still poorly understood. The purpose of this study is to use the novel validation-based insertional mutagenesis (VBIM) technique to identify carboplatin resistance gene in A2780 OC cells. A2780 cells were infected with VBIM virus to cause the overexpression of drug resistance genes, then were further selected under carboplatin treatment. Targeted gene was then identified by using VBIM specific primers. In a preliminary screen, we identified the novel carboplatin resistance gene 1 (NCR1). Overexpression of NCR1 increased carboplatin resistance in A2780 OC cells, while knocking it down with shRNA had the opposite effect. In an attempt to investigate the molecular mechanism that underlying NCR1-mediated carboplatin resistance, we found that NCR1 is a potential NF-κB activator. In summary, we conclude that using a novel VBIM technique, we discovered a previously unknown carboplatin resistance gene NCR1, which may mediate drug resistance via NF-κB signaling pathway. This study is of extreme importance by identifying a potential novel therapeutic target NCR1 in carboplatin resistance. Development of small chemical inhibitors targeting NCR1 could ultimately lead to novel therapeutic approach for ovarian cancer treatment.

Citation Format: Han Wei, Yun She, Tao Lu. Identification of novel carboplatin resistance gene in ovarian cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3759. doi:10.1158/1538-7445.AM2014-3759
Abstract 3761: Nanoliposomal c-MYC-siRNA inhibits in vivo tumor growth of cisplatin-resistant ovarian cancer
Authors: Reyes-González Jeyshka M. , Armaiz Guillermo N. , Mangala Lingegowda S. , Valiyeva Fatma , Pradeep Sunila , Sood Anil K. , Vivas-Mejía Pablo E.
Published: May 2015

Ovarian cancer is the deadliest of gynecological cancers in the United States. With fewer than 15% of cases diagnosed early, ovarian cancer continues to be characterized by late-stage presentation. Treatment for ovarian cancer usually involves surgical cytoreduction followed by platinum-based chemotherapy. Unfortunately, despite initial respond, more than 70% of ovarian cancer patients develop cisplatin resistance, relapse and therapeutic failure. Therefore, there is a need of novel therapies focused on targets within cancer cell survival pathways for advanced stage drug resistant ovarian cancer. Evidence indicates that activation of the oncogenic transcription factor c-MYC is involved in drug resistance. Our previous findings indicate that cisplatin-resistant ovarian cancer cells express higher c-MYC protein levels when compared to their sensitive counterparts. Importantly, targeting c-MYC with small interfering RNA (siRNA) in the cisplatin-resistant ovarian cancer cell line, A2780CP20, induced a significant cell growth arrest and inhibition of cell proliferation. Apoptosis and arrest of cell cycle progression were also observed after siRNA-based silencing of c-MYC. These results were confirmed by Western blot analysis. Furthermore, in vivo delivery of c-MYC-siRNA in a murine xenograft model of cisplatin-resistant ovarian cancer was achieved by using DOPC/PEG-2000-based nanoliposomes. A single weekly injection of nanoliposomal c-MYC-siRNA, during a four week period, decreased tumor weight and number of tumor nodules compared with a liposomal-negative control siRNA. These data propose c-MYC as a potential therapeutic target for cisplatin-resistant ovarian cancer.

Citation Format: Jeyshka M. Reyes-González, Guillermo N. Armaiz, Lingegowda S. Mangala, Fatma Valiyeva, Sunila Pradeep, Anil K. Sood, Pablo E. Vivas-Mejía. Nanoliposomal c-MYC-siRNA inhibits in vivo tumor growth of cisplatin-resistant ovarian cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3761. doi:10.1158/1538-7445.AM2014-3761
Abstract 3765: Indoleamine 2,3-dioxygenase mediates immune-independent human tumor cell resistance to olaparib, γ radiation, and cisplatin
Authors: Vareki Saman Maleki , Rytelewski Mateusz , Figueredo Rene , Chen Di , Ferguson Peter J. , Vincent Mark , Min Weiping , Zheng Xiufen , Koropatnick James
Published: May 2015

Indoleamine 2,3-dioxygenase-1 (IDO) is an immunosuppressive molecule expressed by most human tumors. IDO levels correlate with poor prognosis in cancer patients and IDO inhibitors are under investigation to enhance endogenous anticancer immunosurveillance. Little is known of immune-independent functions of IDO relevant to cancer therapy. We show, for the first time, that IDO mediates human tumor cell resistance to a PARP inhibitor (olaparib), γ radiation, cisplatin, and combined treatment with olaparib and radiation, in the absence of immune cells. Antisense-mediated reduction of IDO, alone and (in a synthetic lethal approach) in combination with antisense to the DNA repair protein BRCA2 sensitizes human lung cancer cells to olaparib and cisplatin. Antisense reduction of IDO decreased NAD+ in human tumor cells. NAD+ is essential for PARP activity and these data suggest that IDO mediates treatment resistance independent of immunity and at least partially due to a previously unrecognized role for IDO in DNA repair. Furthermore, IDO levels correlated with accumulation of tumor cells in G1 and depletion of cells in G2/M of the cell cycle, suggesting that IDO effects on cell cycle may also modulate sensitivity to radiation and chemotherapeutic agents. IDO is a potentially valuable therapeutic target in cancer treatment, independent of immune function and in combination with other therapies.

Supported by grants to JK and WM from the Canadian Institutes of Health Research (CIHR).

Citation Format: Saman Maleki Vareki, Mateusz Rytelewski, Rene Figueredo, Di Chen, Peter J. Ferguson, Mark Vincent, Weiping Min, Xiufen Zheng, James Koropatnick. Indoleamine 2,3-dioxygenase mediates immune-independent human tumor cell resistance to olaparib, γ radiation, and cisplatin. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3765. doi:10.1158/1538-7445.AM2014-3765
Abstract 3766: The response of cervical cancer cells to chemotherapeutic agents depends on endogenous ROS levels as well as the drug-induced ROS profile
Authors: Filippova Maria
Published: May 2015

Worldwide, cervical cancer is the second most common cancer in women; approximately 400,000 new cases of this disease are diagnosed each year, of which approximately half will lead to death. Treatment of advanced and relapsed cervical cancer is frequently ineffective, due in large part to chemoresistance. To examine the pathways responsible, we employed the cervical carcinoma-derived SiHa and CaSki cells as cellular models of resistance and sensitivity, respectively, to treatment with chemotherapeutic agents. In particular, CaSki cells are much more sensitive than are SiHa cells to cell death induced by doxorubicin and cisplatin. In this study, we compared the proteomic profiles of SiHa and CaSki cells, and identified pathways with the potential to contribute to the differential response. Based on the results from this proteomic analysis, we hypothesized that pathways involved in the regulation of reactive oxygen species (ROS) levels might contribute in to the observed difference in how these two cell lines respondse to chemotherapy. We then extended these findings by analyzing and comparing the expression level of genes involved in reactive oxygen species (ROS) metabolism through the use of an RT PCR array, and. We found outdiscovered that cells resistant and sensitive cells to drug treatment had displayed different expression levels of expression of pro- and anti-oxidant enzymes. Decreasing or increasing oxidative stress led to protection or sensitization, respectively, to drug-induced cell death, supporting the idea that cellular levels of oxidative stress affect responsiveness to treatment. Interestingly, the two agents tested, doxorubicin and cisplatin, induced different profiles of ROS, and these differences appear to contribute to the differential sensitivity displayed by cervical cancer cells to treatment. Overall, our findings demonstrate that cervical cancer cells display variable profiles with respect to their redox-generating and -adaptive systems, and that these different profiles have the potential to contribute to their differential responses to treatments with chemotherapeutic agents.

Citation Format: Maria Filippova. The response of cervical cancer cells to chemotherapeutic agents depends on endogenous ROS levels as well as the drug-induced ROS profile. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3766. doi:10.1158/1538-7445.AM2014-3766
Abstract 3768: C3: A small molecule that reverses chemoresistance by inhibition of cell cycle arrest
Authors: Wolak Kathryn Elizabeth , Onel Kenan
Published: May 2015

Emergence of chemoresistance is the major cause of death in patients with cancer. To discover compounds that might reverse chemoresistance, we undertook a compound screen to identify molecules that would convert a resistance cell into one that is sensitive. We performed this screen in WTK1, a lymphoblastoid cell line with mutant p53 known to be resistant to chemotherapy. We conducted a high-throughput screen using 83,745 small molecules in the presence or absence of daunorubicin at an IC25 to identify novel compounds that prime cells for chemotherapy-induced apoptosis. We identified C3 as a “hit,” defined as a compound that did not significantly alter viability of cells alone, but significantly increased daunorubicin-induced cell death. We confirmed the effects C3 in a variety of cell types including leukemia, colon, neuroblastoma, breast and ovarian. To determine whether this effect was specific to daunorubicin, we assessed C3's ability to synergize with a wide variety of other genotoxic agents and found that it was highly synergistic with platinating agents. Because cisplatin resistance is the major obstacle in ovarian cancer treatment, we used ovarian cancer lines in our mechanistic studies. We found that C3 synergizes with cisplatin and daunorubicin in a caspase-3 dependent manner, but the mechanism by which C3 primes cells for death did not involve mismatch repair or mitochondrial membrane permeability. Because cisplatin and daunorubicin induce cell cycle arrest, we hypothesized that C3 might alter the regulation of progression of the cell cycle. We found that while cisplatin and daunorubicin have arrested cell cycle profiles on their own, the profiles appear normal when combined with C3 before the cells die. These observations suggest a novel mechanism in which C3 induces apoptosis by forcing cells with damaged genomes through the cell cycle, resulting in apoptosis.

Citation Format: Kathryn Elizabeth Wolak, Kenan Onel. C3: A small molecule that reverses chemoresistance by inhibition of cell cycle arrest. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3768. doi:10.1158/1538-7445.AM2014-3768
Abstract 3769: K-ras Silencing has diverse effect on the response of cells to chemotherapeutic drugs
Authors: Teimoori-Toolabi Ladan , Azadmanesh Kayhan , Khorramizadeh Mohammadreza , Hashemi Saba
Published: May 2015

Introduction: Drug resistance in different types of cancer arise serious concerns in oncology. Different genes and signaling pathways are responsible for this resistance. K-ras is one of the important signaling pathways in cancer. This pathway is activated in 50% of all types of cancer. In this study we aimed to study the effect of silencing RAS signaling pathway on the response of Hct116 as a colon cancer cell line to 5-flurouracil and oxaliplatin as the common chemotherapeutic drugs.

Materials and methods: Two oligonucleotides silencing the wild type k-ras were selected by different online programs such as Dharmcon, Invitrogen and Promega. After insertion of these oligonucleotides into psilencer neo2.1, they were transfected into HCT116 cell line. Thereafter the lethality of 5-fluouracil and oxaliplatin in these cells was assessed by XTT proliferation assay kit.

Results:

Plasmids containing oligonucleotides silencing wild type were named p565ks and p688ks according to the site of silencing within the k-ras mRNA. Quantitative PCR analysis showed that silencing k-ras was more profound in HCT565ks. After stably transfecting Hct116 cell line with these plasmids, these cells were named HCT565ks and HCT688ks. While the LC50 of 5-flurouracil for Hct116 was 13-15µM, for HCT565ks and HCT688ks, it was 37.5-40 µM and 22.5-25 µM. While the LC50 of oxaliplatin for HCT116 was 8.75 µM, in HCT565ks and HCT688ks LC50s were 0.35 µM and 0.3 µM. These data showed that silencing k-ras have made the cells more resistant to 5-flurouracil while it increased the sensitivity of cells to lethal effects of oxaliplatin.

Conclusion: In conclusion silencing k-ras had different effects on the response of cells to different chemotherapeutic drugs. This can urge us to be more cautious about prescribing RAS inhibiting drugs as it may cause the cells to become more resistant to some chemotherapeutic drugs such as 5-flurouracil while they may be killed more by other drugs such as oxaliplatin.

Citation Format: Ladan Teimoori-Toolabi, Kayhan Azadmanesh, Mohammadreza Khorramizadeh, Saba Hashemi. K-ras Silencing has diverse effect on the response of cells to chemotherapeutic drugs. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3769. doi:10.1158/1538-7445.AM2014-3769
Abstract 377: SMYD2-dependent PARP1 methylation promotes Poly(ADP-ribosyl)ation activity in cancer cells
Authors: Piao Lianhua , Nakamura Yusuke , Hamamoto Ryuji
Published: May 2015

Poly(ADP-ribose) polymerase-1 (PARP1) catalyzes the poly(ADP-ribosyl)ation of protein acceptors using NAD+ as the substrate is now considered as an important target for development of anticancer therapy. PARP1 is known to be posttranslationally modified in various ways including phosphorylation and ubiquitination, but the physiological role of PARP1 methylation is not well understood. Here we demonstrated that the histone methyltransferase SMYD2 (SET and MYND domain containing 2), which plays critical roles in human carcinogenesis, mono-methylated PARP1. We found lysine 528 to be a target of SMYD2-dependent PARP1 methylationa and that an N-Terminal DNA binding domain of PARP1 interact with an N-terminal domain of SMYD2. Importantly, methylated PARP1 revealed enhanced poly(ADP-ribose) formation after oxidative stress, and positively regulated the poly(ADP-ribosyl)ation activity of PARP1. Hence, our study unveils a novel mechanism of PARP1 in human cancer through its methylation by SMYD2.

Citation Format: Lianhua Piao, Yusuke Nakamura, Ryuji Hamamoto. SMYD2-dependent PARP1 methylation promotes Poly(ADP-ribosyl)ation activity in cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 377. doi:10.1158/1538-7445.AM2014-377
Abstract 3770: MLN4924, a neddylation inhibitor, abolishes chemoresistance of bladder cancer stem-like cells through suppression of stemness
Authors: Kuo Kuan-Lin , Ho I-Lin , Pu Yeong-Shiau , Tsai Yu-Chieh , Shih Tsung-Hsien , Huang Kuo-How
Published: May 2015

Introduction:

Bladder urothelial carcinoma (UC) ranks fourth in incidence among cancers in men and eighth in women in the United States, however, the chemotherapy response rate is only about half. The cancer stem cells (CSCs), which are believed as the driving force of tumor progression, have related to chemoresistance. Here we present the finding of CSC-like cells from human UC cell line NTUB1, and investigate the effect of MLN4924, a neddylation inhibitor on conquering chemoresistance in human UC.

Materials & methods:

The CSC-like cells were enriched from its parental cell line NTUB1 by cisplatin selection consecutively for at least one year. The properties of CSC-like cells were demonstrated by colony formation assay, side population assay, and cell viability assay. The expression levels of specific stemness-related markers, EMT-related markers and cell death-related molecules were revealed by western blot. The ability of migration was analyzed by wound-healing assay and transwell assay. The MLN4924-induced apoptosis on CSC-like cells were determined by flow cytometry with annexin V and propidium iodide (PI) staining. Gene knockdown was performed with gene-specific siRNA. The in vitro findings were further confirmed in vivo via xenograft mouse model.

Results:

The CSC-like cells exhibited multiple drug resistance, highly expression level of stemness markers as well as EMT markers, and highly mobility. The treatment of MLN4924 repressed the expression of stemness markers and EMT markers and reduced cell mobility; meanwhile, it caused significant cell death in CSC-like cells. The knockdown of stemness markers diminished the drug resistance of CSC-like cells. And in the end, MLN4924 significantly inhibit tumor growth in xenograft models bladder cancer stem-like cells.

Conclusion:

Our data suggested that the drug resistance in UC may conferred by CSC-like cells via up-regulation of stemness markers, and the treatment of MLN4924 could abolish drug resistance through repression of stemness markers. This could provide a new remedy for bladder cancer treatment.

Citation Format: Kuan-Lin Kuo, I-Lin Ho, Yeong-Shiau Pu, Yu-Chieh Tsai, Tsung-Hsien Shih, Kuo-How Huang. MLN4924, a neddylation inhibitor, abolishes chemoresistance of bladder cancer stem-like cells through suppression of stemness. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3770. doi:10.1158/1538-7445.AM2014-3770
Abstract 3775: Identification of PHF6 as a temozolomide resistance factor in glioblastoma using mirConnX
Authors: Hiddingh Lotte , Raktoe Rajiv S. , Kaspers Gertjan J.L. , Vandertop W. Peter , Noske David P. , Wesseling Pieter , Wurdinger Thomas
Published: May 2015

Background: Intrinsic and acquired resistance to temozolomide (TMZ) represents a major obstacle in the treatment of glioblastoma. MicroRNAs (miRNAs) have previously been implicated to play a role in chemoresistance including TMZ resistance. These short non-coding RNA sequences inhibit their mRNA targets, thereby contributing to treatment resistance. In this study, we examined the miRNA/mRNA interaction networks in TMZ resistant glioblastoma cell lines to identify drug targets for the reversal of TMZ resistance. Methods: TMZ resistance was induced in duplicate in the glioblastoma cell lines U87, Hs683, and LNZ308, creating two independent resistant subclones of each wildtype cell line. IC50 values were increased at least two-fold in the TMZ resistant subclones compared to their wildtype. mRNA and miRNA expression profiles of these cell lines were obtained by microarray data analysis. Next, we used these mRNA and miRNA expression profiles of the TMZ resistant cells to generate miRNA/mRNA interaction networks using the integrative network tool mirConnX. This tool combines sequence information with gene expression data analysis to create a condition-specific regulatory network. Results: In the obtained mRNA/miRNA network of our TMZ resistant cell lines, we identified the plant homeodomain (PHD)-like finger 6 (PHF6) mRNA to be targeted by the largest set of miRNAs, i.e. miR-143, miR-93, miR-183, miR-96, and miR-214. Analysis of PHF6 mRNA expression in the TMZ resistant subclones by qRT-PCR showed an increased expression of this mRNA in four of six resistant subclones. Protein expression analysis of PHF6 in these cell lines showed a modest increase in four of the six resistant subclones. Furthermore, analysis of mRNA and protein expression levels of PHF6 in glioblastoma patient datasets showed increased expression of PHF6 in glioblastoma tissue compared to normal brain tissue. In addition, knockdown of PHF6 using siRNA in combination with TMZ enhanced the TMZ response. These results suggest that PHF6 is a candidate drug target for the potentiation of TMZ efficacy. Conclusion: Altogether, these results demonstrate that mirConnX is a useful tool to investigate miRNA/mRNA interactions in TMZ resistant cells and can be used to identify new potential drug targets.

Citation Format: Lotte Hiddingh, Rajiv S. Raktoe, Gertjan J.L. Kaspers, W. Peter Vandertop, David P. Noske, Pieter Wesseling, Thomas Wurdinger. Identification of PHF6 as a temozolomide resistance factor in glioblastoma using mirConnX. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3775. doi:10.1158/1538-7445.AM2014-3775
Abstract 3778: Glioblastoma multiforme utilizes system Xc- in survival under oxidative stress and chemoresistance
Authors: Reveron Rosyli F. , Polewski Monika D. , Aboody Karen S.
Published: May 2015

Glioblastoma multiforme (GBM) is the most common and aggressive malignant primary brain tumor in humans, with a median survival rate of 10-15 months and a five year survival rate of 2.9% from initial diagnosis. Characteristically, GBM exhibits high proliferation and metabolism rates as well as low reactive oxygen species (ROS) production that is sustained using a sodium-independent, electro-neutral transporter known as system XC-. System XC- is composed of a regulatory heavy subunit (4F2hc) linked to a catalytic light subunit (xCT). This protein complex mediates the uptake of L-cystine into the cell, and L-glutamate out of the cell, at a 1:1 ratio. Imported cystine is reduced to L- cysteine, the rate limiting substrate in glutathione (GSH) synthesis. Glutathione is an essential antioxidant in the central nervous system that is responsible for maintaining intracellular redox homeostasis by neutralizing ROS. High intracellular GSH levels in cancer cells are associated with drug resistance and detoxification of alkylating agents such as temozolomide (TMZ). Therefore, system XC- expressed in glioma cells may be used as a target to reduce glioma survival and tumor burden. Sulfasalazine inhibits system Xc- and demonstrated a strong antitumor potential in preclinical models of malignant glioma. However, the first clinical trial using sulfasalazine to treat GBM patients was terminated due to off-target effects. To further elucidate the protective role of system XC- in GBM, we generated stable xCT knock-down and over-expressing U251 glioma cells. These lines were characterized for survival, proliferation, apoptosis and resistance to insult. The xCT-over-expressing cells were more resistant to hydrogen peroxide treatment and GSH depletion. Interestingly, over-expression of system XC- in U251 cells also resulted in decreased sensitivity to TMZ treatment compared to parental and empty vector controls. As expected, xCT-knock-down cells exhibited increased intracellular ROS after treatment. Using glioma lines stably transduced to over-express or knock-down xCT, we demonstrate for the first time that system XC- over-expression in GBM not only promotes survival under oxidative stress but may also modulate sensitivity to chemotherapy treatment. Therefore, therapeutic manipulation of this transporter either alone or in combination with other treatments may improve clinical outcome in patients diagnosed with GBM.

Citation Format: Rosyli F. Reveron, Monika D. Polewski, Karen S. Aboody. Glioblastoma multiforme utilizes system Xc- in survival under oxidative stress and chemoresistance. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3778. doi:10.1158/1538-7445.AM2014-3778
Abstract 3786: Gambogic acid inhibits chemokine receptor CXCR4 signaling pathways and osteoclastogenesis in multiple myeloma
Authors: Pandey Manoj K. , Kale Vijay P. , Song Chunhua , Sung Shen-shu , Sharma Arun K. , Dovat Sinisa , Amin Shantu G.
Published: May 2015

Bone disease, characterized by the presence of lytic lesions and osteoporosis is the hallmark of multiple myeloma (MM). Stromal cell-derived factor 1α (SDF-1α) and its receptor, CXC chemokine receptor 4 (CXCR4), has been implicated as a regulator of bone resorption, suggesting that agents that can suppress SDF1α/CXCR4 signaling might inhibit osteoclastogenesis, a process closely linked to bone resorption. We, therefore, investigated whether gambogic acid (GA), a xanthone, could inhibit CXCR4 signaling and suppress osteoclastogenesis induced by MM cells. Through docking studies we predicted that GA directly interacts with CXCR4. This xanthone down-regulates the expression of CXCR4 on MM cells in a dose- and time-dependent manner. The down-regulation of CXCR4 was not due to proteolytic degradation but rather to transcriptional regulation, as indicated by down-regulation of CXCR4 mRNA expression, inhibition of nuclear factor-kappa B (NF-κB) activity, and suppression of p65 binding at CXCR4 promoter analyzed by quantitative chromatin immunoprecipitation (qChIP) assay. Suppression of CXCR4 expression by GA correlated with both inhibition of SDF-1α-induced invasion of MM cells. GA also inhibited phosphorylation of Akt, p38, and Erk1/2 in MM cells. GA suppressed the RANKL-induced differentiation of macrophages to osteoclasts in a dose- and time-dependent manner. Finally, we found that MM cells, induced differentiation of macrophages to osteoclasts, and that GA suppressed this process. Overall, our results show that GA is a novel inhibitor of CXCR4 expression and thus has a strong potential to suppress osteoclastogenesis mediated by MM cells.

Citation Format: Manoj K. Pandey, Vijay P. Kale, Chunhua Song, Shen-shu Sung, Arun K. Sharma, Sinisa Dovat, Shantu G. Amin. Gambogic acid inhibits chemokine receptor CXCR4 signaling pathways and osteoclastogenesis in multiple myeloma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3786. doi:10.1158/1538-7445.AM2014-3786
Abstract 3790: Artesunate inhibits multiple proinflammatory transcription factors leading to the suppression of growth and induction of apoptosis in prostate cancer cells
Authors: Nachiyappan Alamelu , Shanmugam Muthu K , Li Feng , Kumar Alan Prem , Sethi Gautam
Published: May 2015

Prostate cancer (PCa) is common and a frequent cause of cancer death among men worldwide. Moreover, PCa rates have risen quite significantly in the last decade in Singapore men and although some of the increase can be attributed to enhanced detection, much of the increased incidence is associated with genetic alterations and life-style related factors. Current therapies for metastatic prostate cancer are only marginally effective, and hence new treatment modalities are urgently needed. Considerable evidence suggests that chronic inflammation plays a pivotal role in the development and progression of PCa. Thus, the agents that can suppress inflammatory mediators have a potential in treatment of PCa. One way to expedite drug development is to find new uses for drugs already in clinical use. Hence we propose to investigate the role of artesunate, (a drug approved for the treatment of multidrug-resistant malaria) in PCa using diverse prostate cancer cell lines. In this study, we investigated the effect of artesunate (ART) primarily on signal transducer and activator of transcription 3(STAT3) signaling pathway in both androgen independent (DU145) and androgen dependent (LNCaP) PCa cell lines and also prospectively tested the hypothesis of NF-κB and STAT3 inhibition using a virtual predictive functional proteomics tumor pathway technology platform. We found that ART inhibited constitutive and IL-6-induced activation of STAT3 in DU145 and LNCaP cells in a dose and time dependent manner. We observed that STAT3 suppression by ART was mediated through the inhibition of activation of upstream kinases such as (c-Src, JAK1, and JAK2) and generation of reactive oxygen species (ROS) was also involved in this process. Our preliminary findings further indicate that ART also suppressed constitutive NF-κB activation in PCa cells. ART exhibited significant anti-proliferative effects and abrogated the migratory/invasive potential of PCa cells. Moreover, ART down-regulated the expression of various NF-κB and STAT3 regulated gene products involved in proliferation, survival and angiogenesis, also induced apoptosis in PCa cells lines as evident by DNA fragmentation and Annexin V staining. Overall our preliminary results from experimental and predictive studies indicate that ART mediates its anti-tumor effects through suppression of NF-κB and STAT3 pathways in PCa.

Citation Format: Alamelu Nachiyappan, Muthu K Shanmugam, Feng Li, Alan Prem Kumar, Gautam Sethi. Artesunate inhibits multiple proinflammatory transcription factors leading to the suppression of growth and induction of apoptosis in prostate cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3790. doi:10.1158/1538-7445.AM2014-3790
Abstract 3792: Upregulation of TNF-α by ethanol extract of Moringa oleifera leaves in benzene-induced leukemic Wister rat: a possible mechanism of anticancer property
Authors: Akanni Olufemi E. , Adedeji Adebayo L. , Oloke Kola J.
Published: May 2015

Ethanol extract of Monringa oleifera leaves has been shown to possess anticancer properties in animal models. The mechanisms of action of its anticancer properties have not been fully demonstrated. In this study, we induced leukemia in two groups of 7 rats each by intravenous injection of benzene chromasolv solution (0.2 mL) 48 hourly for 4 weeks. The extract (0.2 ml of 100 mg/mL) was administered orally by gavage, after leukemia induction, daily for 4 weeks to one of the groups while the other group was not treated. The third group served as the normal control. At the end of the treatment, the rats were immobilized by cervical dislocation and blood samples were collected by cardiac puncture. Plasma concentrations of Beta-2 Microglobulins (β2M), Perforins (PF), Interleukin-2(IL2), Interferon-gamma (IFN-γ) and Tumour Necrosis Factor-alpha (TNF-α) were determined by standard commercial ELISA Results showed that leukemia was induced within 4 weeks as a significantly elevated leukocyte count and plasma β2M concentration over the baseline were noted (p< 0.05). Plasma IL2 and TNF-α were also significantly elevated while PF and IFN-γ decreased significantly in Moringa oleifera leaves extract treated rats compared with untreated groups. Since IL2 and PF are associated with cytotoxicity of CD8 T lymphocytes, reduced expression of PF in the face of increasing plasma concentration of IL-2 suggests that Moringa oleifera extract may not exert its anticancer properties via direct cytotoxicity. We thus concluded that increased expression TNF-α may translate to enhanced apoptosis and may be a possible mechanism of action.

Citation Format: Olufemi E. Akanni, Adebayo L. Adedeji, Kola J. Oloke. Upregulation of TNF-α by ethanol extract of Moringa oleifera leaves in benzene-induced leukemic Wister rat: a possible mechanism of anticancer property. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3792. doi:10.1158/1538-7445.AM2014-3792
Abstract 3793: Effects of DCA and metformin on murine colon cancer growth
Authors: Sticca Robert P. , Murphy Tonya C.
Published: May 2015

Background: Dichloroacetate (DCA) and metformin (M) have been reported to have many effects on cancer cells including alterations in pH homeostasis and glucose metabolism, cell cycle arrest, induction of autophagy and modulation of the tumor microenvironment. These effects have been shown to increase tumor apoptosis, inhibit neoplastic cell proliferation, improve the immune response against tumor cells and decrease the protective inflammatory response in tumors, which has led to the investigation of these drugs as anticancer agents. This study examines the effects of DCA and metformin in a murine colon cancer model both in vivo and in vitro.

Methods: Murine colon cancer cell lines (ATCC CT26-CL25, CT26-WT) and cells isolated from subcutaneous metastatic colon cancer tumors (CT71911) were grown in the presence of DCA (serial concentrations from 12 mM to 192mM) and M (serial concentrations from 8 mM to 48 mM). Viable cells were counted and averaged for 3 separate assays. Balb/c mice in triplicate were injected IP with serial concentrations of DCA and M (8,24,48 mM) beginning one day prior to tail vein administration of 7.5 x 103 colon cancer cells (CT26-WT, CT71911). Daily IP injections of DCA and M were continued for 6 weeks or until the mice succumbed to metastatic cancer. All mice were autopsied and cause of death was recorded.

Results: All three cell lines demonstrated a linear reduction in growth and increased apoptosis with increasing concentrations of DCA. All tumor cells were killed at concentrations above 96 mM. M was cytostatic but not cytotoxic for all three cell lines with minimal growth at 8 mM and no growth at higher concentrations. In vivo, administration of IP DCA prolonged survival by 80 - 89% (days after tumor challenge), while IP metformin prolonged survival by 35 - 38%. Increased survival with both DCA and M was not dose dependent with variation between concentrations less than 10%. All mice died of lung metastases.

Conclusion: Both DCA and M demonstrated beneficial effects on murine colon cancer cells with reductions in cell growth and increased apoptosis in vitro and increased survival in vivo. M exhibited cytostatic activity and a lower improvement in survival while DCA exhibited cytotoxic activity and a longer survival benefit. Further investigation in the use of these agents as adjunct therapies for colon cancer is warranted.

Citation Format: Robert P. Sticca, Tonya C. Murphy. Effects of DCA and metformin on murine colon cancer growth. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3793. doi:10.1158/1538-7445.AM2014-3793
Abstract 380: Discovery of new epigenetic drugs among FDA-approved drug libraries
Authors: Raynal Noël J. , Lee Justin T. , Wang Youjun , Garriga Judith , Malouf Gabriel , Dumont Sarah , Dettman Elisha J. , Gharibyan Vazganush , Ahmed Saira , Chung Woonbok , Childers Wayne E. , Abou-Gharbia Magid , Henry Ryan A. , Andrews Andrew , Jelinek Jaroslav , Cui Ying , Baylin Stephen B. , Gill Donald L. , Issa Jean-Pierre J.
Published: May 2015

Targeting epigenetic pathways to induce tumor suppressor gene reactivation is a promising approach for cancer therapy. Epigenetic drugs produce impressive responses in some patients; however, treatment options are limited to a small number of drugs. We screened drug libraries for epigenetic activity using a live cell-based assay. We found that around 1% of US-FDA approved drugs have significant epigenetic activity detected by GFP reactivation of a DNA methylated and silenced promoter in colon cancer cells. Newly identified drugs, most prominently cardiac glycosides, induced tumor suppressor gene reactivation and showed selective anticancer apoptosis induction. These drugs did not change DNA methylation or histone acetylation globally but induced gene reactivation and cancer cell killing through calcium signaling leading to nuclear exclusion of chromatin repressors. Our data identify new epigenetic drugs that can be rapidly repurposed for cancer clinical trials and raise questions about the safety of commonly used medications.

Citation Format: Noël J. Raynal, Justin T. Lee, Youjun Wang, Judith Garriga, Gabriel Malouf, Sarah Dumont, Elisha J. Dettman, Vazganush Gharibyan, Saira Ahmed, Woonbok Chung, Wayne E. Childers, Magid Abou-Gharbia, Ryan A. Henry, Andrew Andrews, Jaroslav Jelinek, Ying Cui, Stephen B. Baylin, Donald L. Gill, Jean-Pierre J. Issa. Discovery of new epigenetic drugs among FDA-approved drug libraries. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 380. doi:10.1158/1538-7445.AM2014-380
Abstract 3802: Withacnistin blocks binding of STAT3 and STAT5 to growth factor and cytokine receptors and induces regression of breast tumors in vivo
Authors: Zhang Xiaolei , Blaskovich Michelle A. , Forinash Kara D. , Sebti Said M.
Published: May 2015

The binding of STAT3 and STAT5 to growth factor and cytokine receptors such as EGFR and the IL-6 receptor gp130 is critical to their activation and ability to contribute to malignant transformation. Therefore, interfering with these biochemical processes could lead to the discovery of novel anti-cancer agents. In this manuscript, we show that the natural product, Withacnistin (Wit) blocks EGF- and IL-6-stimulated binding of STAT3 and STAT5 to EGFR and gp130. Furthermore, Wit inhibits EGF-, PDGF-, IL-6-, IFNβ- and GM-CSF-stimulation of tyrosine phosphorylation of STAT3 and STAT5 but not of EGFR or PDGFR. The inhibition of P-STAT3 and P-STAT5 occurred very rapidly, within minutes of Wit treatment and growth factor stimulation. Wit also inhibits STAT3 nuclear translocation, DNA binding, promoter transcriptional activation, and it suppresses the expression levels of STAT3 target genes such as Bcl-xL and Mcl-1. Finally, Wit induces apoptosis, inhibits anchorage-independent growth and invasion, and causes breast tumor regression in an ErbB2-driven transgenic mouse model. These data warrant further development of Wit as a novel anti-cancer drug for targeting tumors that harbor hyperactivated STAT3 and STAT5.

Citation Format: Xiaolei Zhang, Michelle A. Blaskovich, Kara D. Forinash, Said M. Sebti. Withacnistin blocks binding of STAT3 and STAT5 to growth factor and cytokine receptors and induces regression of breast tumors in vivo. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3802. doi:10.1158/1538-7445.AM2014-3802
Abstract 3807: A novel imidazole derivate inhibits STAT3 activation via induction of SHP-1 hepatocellular carcinoma
Authors: Su Jung-Chen , Wu Szu-Hsien , Chen Kuen-Feng , Tai Wei-Tien , Huang Jui-Wen , Shiau Chung-Wai
Published: May 2015

The activation of STAT3 signaling cascade has been linked with cell survival, proliferation, and angiogenesis in HCC. Literature have shown that overexpression of SHP-1 suppressed cell proliferation in varies cancer cells. Compounds that can activate SHP-1 and further repress STAT3 activity pathway have potential for treatment of HCC. We investigated whether imidazole derivates can modulate the SHP-1/STAT3 pathway. The result showed that imidazole derivate inhibited both constitutive and interleukin 6-inducible STAT3 phosphorylation in HCC cells and induced cell apoptosis. In addition, we explored protein tyrosine phosphatases (SHP-1 and SHP-2) expression level in HCC cells with the treatment of the imidazole derivate. Interestingly, the imidazole derivate significantly induced the expression of SHP1 and subsequently inhibited the phosphorylation of Src , Jak2 and STAT3. This agent also repressed the expression of STAT3-regulated target genes, including cyclin D1, Mcl-1, and survivin. Overall, our results suggest that the imidazole derivate blocks STAT3 activation through up-regulation of SHP-1, and this may have potential for combination with other chemotherapeutic agents.

Citation Format: Jung-Chen Su, Szu-Hsien Wu, Kuen-Feng Chen, Wei-Tien Tai, Jui-Wen Huang, Chung-Wai Shiau. A novel imidazole derivate inhibits STAT3 activation via induction of SHP-1 hepatocellular carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3807. doi:10.1158/1538-7445.AM2014-3807
Abstract 3819: Clinical potential of the Eph/ephrin profile in breast cancer
Authors: Perez-Tenorio Gizeh , Husa Anna-Maria , Stål Olle
Published: May 2015

The Eph receptors belong to a large family of receptors tyrosine kinase. The Ephs and their ligands ephrins are aberrantly expressed in cancer. However, due their complex signaling and promiscuous interactions, a wide screening of the entire family will be important to determine their clinical value. Purpose: The Eph receptor tyrosine kinase family has been implicated in breast cancer but their role in tumor progression remains elusive. Therefore we aimed to profile the Eph receptors and their ligands ephrins in breast cancer samples to define them as potential clinical markers or therapeutic targets.

Experimental design: Gene expression of Eph/ephrins was quantified by RT-PCR using a TaqMan® Micro Fluidics Cards Microarray custom designed for 21 Eph/ephrin family members: EphA1-A8, EphB1-B4 and EphB6, ephrinA1-A5, ephrinB1-B3 and 2 endogenous controls: GAPDH and HPRT1 in 70 breast cancer tumors.

Results: We found that high expression of EphBs, and particularly EphB2, was associated to worse outcome among postmenopausal patients with lymph node infiltration. Additionally high EphB2 expression correlated with HER2 positive status.

Conclusions: Our results suggest that the EphB receptor family may have prognostic value for postmenopausal breast cancer patients with lymph nodal infiltration. We will continue this study in a larger patient material in order to better evaluate the therapeutic impact of this family.

Citation Format: Gizeh Perez-Tenorio, Anna-Maria Husa, Olle Stål. Clinical potential of the Eph/ephrin profile in breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3819. doi:10.1158/1538-7445.AM2014-3819