bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 2260: Novel molecular therapy targeting Mcl-1 and modulating autophagy in castration-resistant prostate cancer
Authors: Tang Wenhua , Qu Yang , Lan Lan , Wu Daocheng , Xu Liang 
Published: August 2012

Abstract
Chemo/radioresistance markedly impair the efficacy of cancer therapy. Anti-apoptotic Bcl-2 family proteins such as Bcl-xL, Bcl-2 and Mcl-1 are overexpressed in castration-resistant prostate cancer (CRPC) and contribute to prostate tumor initiation, progression and resistance to radiotherapy. A natural BH3-mimetic small molecule inhibitor of Bcl-2, (-)-gossypol, shows promise in ongoing Phase II clinical trials for human prostate cancer. We have recently shown that (-)-gossypol preferentially induces autophagy in CRPC cells that have high levels of Bcl-2 and are resistant to apoptosis, both in vitro and in vivo, but not in androgen-dependent cells with low Bcl-2 and sensitive to apoptosis. We have explored a series of gossypol derivatives and identified two novel BH3-mimetic lead compounds that are more potent than the parental compound in inducing autophagic cell death in CRPC. A novel pan-Bcl-2 inhibitor, apogossypolone (ApoG2), a derivative of (-)-gossypol, has a better binding affinity to Mcl-1 and an improved antitumor activity, and shows promising efficacy on a variety of cancers in vitro and in vivo. Treatment with the ApoG2 prior to radiotherapy enhances cell death via autophagic pathway in cancer cells which have high Mcl-1 and resistant to apoptosis. In addition to abrogating Bcl-2/Mcl-1–Beclin1 interactions, ApoG2 activates the autophagic pathway Atg5-dependently which synergizes with the effect of radiation. We further investigated the precise mechanism governing the influence of ApoG2 on IR-induced cell death. Our data suggest that, ApoG2 pretreatment suppresses IR induced Akt activation and mTOR phosphorylation. In this way, it serves as a potent radiosensitizer to affect autophagic cell death in cancer cells. Administration of ApoG2 prior to IR further delayed tumor growth of castration resistant prostate cancer xenograft model and increased autophagic cell death in vivo. Together, our data demonstrate a novel mode of action of ApoG2 as an enhancer of radiation induced autophagic cell death and provide mechanistic details of its tumor cell killing activities. These new insights into different modes of cell death induced by Mcl-1 inhibitors may facilitate the rational design of clinical trials by selecting patients most likely to benefit from the Mcl-1-targeted molecular therapy.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2260. doi:1538-7445.AM2012-2260
Abstract 2266: Beclin-1 regulation of autophagy in endocrine resistant breast cancer
Authors: Facey Caroline O. B. , Shajahan Ayesha N. , Clarke Robert 
Published: August 2012

Abstract
Resistance to endocrine therapy occurs in nearly 50% of all patients diagnosed with estrogen receptor ≤ positive breast cancer, thus elucidating mechanism(s) of endocrine resistance is of major importance. To provide a model, we selected MCF7 variants that are estrogen independent and either sensitive (LCC1) or resistant (LCC9) to antiestrogens: Faslodex (FAS; ICI 182, 780) and Tamoxifen (TAM). Antiestrogens induce endoplasmic reticulum stress which, depending on cell type, stimulus, and duration, may subsequently activate the unfolded protein response (UPR), autophagy, and/or apoptosis. Gene microarray analysis of LCC9 cells show high expression levels of X-box binding protein 1 (XBP1), implicating the unfolded protein response (UPR) as a pro-survival mechanism of resistance. In addition to an elevated UPR, autophagy is substantially elevated in response to antiestrogens. To better understand the role of autophagy in antiestrogen responsiveness, we investigated the consequence of knocking down BECLIN-1 in LCC1 and LCC9 cells treated with FAS and TAM. Preliminary results indicate a time-dependent change in autophagy following knock-down of beclin-1 in response to short-term (48h) and long-term (6 day) treatment. At 48h, sensitive LCC1 cells respond to antiestrogens with high levels of autophagy measured by increased LC3BII to LC3BI ratio and decreased expression of p62. Relative cell density (measured by crystal violet assay) decreases by 20% at 48h and by 80% at 6 days in LCC1 cells however, LCC9 cells are minimally affected by antiestrogen treatment. The level of autophagy remains high at 6 days in sensitive cells however levels remain constant in resistant cells. Autophagy is significantly lowered by reduced BECN1 in both sensitive and resistant cells however there is an increase in cell density in sensitive cells transfected with BECN1- shRNA at 6 days, indicating an autophagy associated programmed cell death mechanism in response to antiestrogen treatment. Protein expression of an active form of caspase −12/4 (an initiator caspase activated during endoplasmic reticulum stress) is elevated in sensitive cells at 6 days in response to antiestrogen treatment, also indicating the onset of apoptosis at this time. Elevated expression of Bcl-2 family members in resistant cells may play a more substantial role than BECN1 alone, as the combination of Bcl-2 family protein inhibitors and BECN1-shRNA sensitizes resistant cells to a greater extent. Thus, Bcl-2 family members in resistant cells may play a critical role in managing the balance between cell survival (moderate autophagy) and programmed cell death (excessive autophagy and apoptosis) in response to antiestrogen treatment.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2266. doi:1538-7445.AM2012-2266
Abstract 2267: Inhibition of autophagy in hypoxic HT29 cells reverses hypoxia-induced resistance to oxaliplatin
Authors: Vasilevskaya Irina A. , Selvakumaran Muthu , Roberts David , O'Dwyer Peter J. 
Published: August 2012

Abstract
BACKGROUND: We have shown previously that inhibition of JNK1 renders HT29 colon adenocarcinoma cells more sensitive to hypoxia and/or oxaliplatin due, in part, to impaired autophagy induction. We also showed that the autophagy inhibitor chloroquine sensitizes HT29 to oxaliplatin in vitro and in mouse xenograft model. PURPOSE: Here we investigate further by molecular approaches, including modulation of signaling through JNK, how inhibition of autophagy affects sensitivity of hypoxic colon cancer cells to oxaliplatin. We employed a panel of HT29-derived cell lines: lines stably expressing dominant negative constructs for either JNK1 (HTJ1.3) or JNK2 (HTJ2.2) singly, derivatives of these lines in which the other JNK gene is silenced by viral delivery of shRNA construct (HTJ1s2 and HTJ2s1), as well as HT29-derived lines with down-regulated BclX (HTBX) or Beclin-1 (HTB). RESULTS: We found that down-regulation of JNK1 leads to inhibition of autophagy accompanied by increase in apoptotic (versus necrosis) cell death. Clonogenic assays revealed higher resistance of HTJ1s2 cells to oxaliplatin under hypoxia, whereas HTJ2s1 cells demonstrated slight increase in sensitivity to the drug in this setting. Down-regulation of either Beclin-1 or BclX resulted in significant sensitization to oxaliplatin in oxic and, even more so, in hypoxic conditions (three-folds on average), while exerting differing effects on autophagy induction. CONCLUSIONS: Our data demonstrate that JNK1 plays an important role in autophagy induction under hypoxic conditions in the HT29 colon adenocarcinoma cell line and that its inhibition increases apoptotic cell death in this setting. Inhibition of autophagy induction by down-regulation of JNK1 and knock-down of Beclin-1 or BclX resulted in reversal of oxaliplatin resistance in hypoxic HT29 cells. These findings suggest that targeting these proteins may be of value in colon cancer treatment.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2267. doi:1538-7445.AM2012-2267
Abstract 2284: MIR-200 family as EMT related microRNA in renal cell carcinoma
Authors: Enokida Hideki , Yoshino Hirofumi , Yamasaki Takeshi , Hidaka Hideo , Chiyomaru Takeshi , Nohata Nijiro , Seki Naohiko , Nakagawa Masayuki 
Published: August 2012

Abstract
(Background) Renal cell carcinoma (RCC) is the most common neoplasm of the adult kidney, and clear cell RCC represents the most common renal cancer histology. However surgical treatment is provided for localized disease, relapse or metastasis of the patient is caused in a considerable ratio. At present, metastatic RCC is difficult to treat and the process of metastasis is not well understood. Therefore, it is crucial to find molecular mechanisms based on recent genome analysis in RCC oncogenesis and metastasis. Based on the microRNA (miRNA) expression signature of RCC revealed that miR-200 family significantly reduced in RCC cells. The miR-200 family (miR-200b, miR-200a and miR-429 are encoded by single polycistronic transcript on chromosome 1p36.33 and miR-200c and miR-141 are cluster on chromosome 12 p13.31) of miRNA plays a major role to epithelial to mesenchymal transition (EMT) by targeting transcription repressors, zinc-finger E-box binding homeobox (ZEB1) and ZEB2. In this study, we investigated the functional significance of miR-200 family and identified the novel cancer pathways in RCC. (Methods) Cell proliferation and invasion assay was performed by restoration of mature miR-200 family (miR-200a, miR-200b, miR-200c, miR-429 and miR-141) in RCC cell lines. Genome-wide gene expression analysis was performed to identify the molecular networks of miR-200 family by microarray analysis. (Results) The mRNA expression levels of ZEB1 and ZEB2 were significantly decreased by miR-200 family (miR-200a, miR-200b, miR-200c, miR-429 and miR-141) transfectantion in RCC cells. Restoration of each miRNAs significantly inhibited cell proliferation and invasion in RCC cells. Interestingly, the morphological changes were recognized by miR-200 family transfection in RCC cell lines. Gene expression analysis showed more than ten candidate genes were searched for miR-200 family targets and these genes were up-regulated in RCC clinical specimens. (Conclusions) Our data suggest that miR-200 family function as tumor suppressors in RCC. EMT-related tumor suppressive miR-200 family mediates novel molecular targets provide new insights into the potential mechanisms of RCC oncogenesis and metastasis.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2284. doi:1538-7445.AM2012-2284
Abstract 2286: p53-miR-dependent post-transcriptional circuits: mechanisms, targets and inter-individual variation
Authors: Ciribilli Yari , Bisio Alessandra , Sanctis Veronica De , Vescovo Valerio Del , Lion Mattia , Jegga Anil G. , Denti Michela A. , Inga Alberto 
Published: August 2012

Abstract
Using bioinformatics approaches, we identified a group of candidate microRNAs (miRs) for direct p53 transcriptional control. To validate p53 family-mediated control of the newly predicted target miRs we evaluated the potential for wild type p53, p63α and p73α to transactivate from p53 response elements (REs) mapped at the miR promoters. Results obtained with an established yeast-based assay indicated that the REs found at miR-10b, -23b, -106a, -151, -191, -198, -202, -221, -320, -1204, -1026 genes were responsive to p53 of which 8 were also responsive to p63α or p73α. ChIP assays in doxorubicin-treated HCT116 cells -p53+/+ vs p53-/– revealed moderate p53 occupancy at the miR-202, -1206 sites, and weak occupancy at miR-10b, -191. RT-qPCR analyses in HCT116 and MCF7 cells showed modest doxorubicin- and/or p53-dependent regulation for miR-23b, -151, -191. We then focused on miR-191 and its potential impact on MDM4, an important modulator of p53. The A&gt;C SNP (rs4245739) in the proximal portion of the MDM4 3′UTR occurs in a predicted binding site for miR-191, with the A allele resulting in a mismatch at the predicted miR-191 seed. This SNP is in strong association with the tag-SNP (rs2369244) within the MDM4 haplotype that was reported to impact on cancer risk. Using MCF7 and HCT116 cells that are heterozygous for rs4245739, we examined at the endogenous MDM4 gene level the impact of varying the expression of miR-191. A slight allelic imbalance was observed by allele-specific qPCR when miR-191 was over-expressed, and the co-transfection of miR-34a, for which seed sequences are predicted in the distal portion of the MDM4-3′UTR, had an additive effect, leading to ∼20% reduction of the C-allele. Western blot analyses indicated that steady-state MDM4 protein levels were reduced by miR-191 and/or miR-34a overexpression. Our study reveals additional miRs that could be directly regulated by the p53-family of transcription factors and could contribute to the tuning of p53-induced responses with the possibility of inter-individual variations due to functional SNPs.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2286. doi:1538-7445.AM2012-2286
Abstract 2312: A genomics approach to determining the role of DICER1 in tumorigenesis: Interferon responses in the cancer cell
Authors: Chiappinelli Katherine B. , Haynes Brian C. , Brent Michael R. , Goodfellow Paul J. 
Published: August 2012

Abstract
DICER1 is required for generation of mature microRNAs (miRNAs) and other short noncoding RNAs. Reduced DICER1 levels are associated with adverse outcomes in a variety of cancers and multiple lines of evidence suggest DICER1 is a tumor suppressor. The effects of reduced DICER1 on mRNA transcript abundance in tumor cells remain largely unknown. To determine how reduced DICER1 levels contribute to tumor phenotypes we used shRNA to stably knock down DICER1 in endometrial cancer cell lines for extended periods (up to 25 passages). Reduced DICER1 levels had no effect on cell proliferation but were associated with enhanced cell migration and increased growth in soft agar. MiRNA profiling for the KLE cancer cell line DICER1 knockdowns (two different DICER1 shRNA constructs) revealed that miRNA levels were decreased overall. Not surprisingly, many mRNA transcripts were upregulated in the DICER1 knockdowns. A striking number of interferon stimulated genes (ISGs) showed upregulation. Upregulation of six ISG transcripts was validated by qRT-PCR in three independent knockdowns of DICER1 in KLE cells. IFNα, a key upstream regulator of the interferon response, was significantly increased in DICER1 knockdowns (KLE and additional endometrial cancer cell lines). IFNα protein secreted in media of DICER1 knockdown cells activated an interferon response in HT29 colon carcinoma cells. The majority of ISGs with increased transcript levels lacked miRNA target sequences and as such it seemed unlikely that the increase in expression levels was secondary to reduced miRNA levels. We tested the hypothesis that defects in miRNA processing could trigger an interferon response. We showed that DICER1 knockdowns in which miRNA processing is reduced have increased levels of pre-microRNAs in the cytoplasm. Pre-microRNAs are double-stranded molecules and long enough (60-100 nt) to activate the dsRNA sensors in the cytoplasm, such as Mda5/IFIH1, that typically sense viral dsRNA (&gt; 30 nt) and stimulate the interferon response. Knockdown of DROSHA, necessary for processing of pri-miRNAs to pre-miRNAs, did not result in accumulation of pre-miRNAs and did not cause an interferon response. Our findings suggest elevated pre-microRNA levels trigger the interferon response to double stranded RNA (incompletely processed miRNA and other species). Rescue experiments (restoring DICER1 function) are currently underway to shed additional light on how reduced double-stranded RNA processing might elicit an interferon response. Work is ongoing to determine the relationship between the observed interferon response and the migration and soft agar phenotypes.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2312. doi:1538-7445.AM2012-2312
Abstract 232: Protein kinase C b1 (PKCb1) inhibits the malignant phenotype of the human pancreatic tumor-derived cell line PANC1
Authors: Cirigliano Stéfano M. , Mauro Laura V. , Grossoni Valeria C. , Joffe Elisa D. Bal De Kier , Colombo Lucas L. , Puricelli Lydia I. , Urtreger Alejandro J. 
Published: August 2012

Abstract
Pancreatic cancer is a deadly disease with a 5% overall survival after five years. Different members of the PKC family have been described as modulators of pancreatic cancer progression but, till nowadays, the relevance of each PKC isoform in this process is unclear. The aim of the present work was to study the effect of PKCb1 overexpression, on several critical determinants of tumor progression using the human pancreatic tumor-derived cell line PANC1. Cells were stably transfected with an expression vector containing the full-length PKCb1 gene (PKCb1-PANC1) or with the empty vector, as control (pMTH-PANC1). While no morphologic alterations could be detected in vitro, PKCb1 overexpression induced a significant reduction in the proliferative capacity of PANC1 cells. The reduction in this capacity could be associated with a decrease in Cyclin D1, Cyclin E and phosphorylated ERK1/2 levels, and an increase in p21 expression levels, as measured by Western blot. In addition PKCb1-PANC1 cells showed an increased resistance to cell death induced by serum starvation (% viability: 58.54±4.1 vs 39.29±4.2 in pMTH-PANC1, p&lt;0.05). Using flow cytometry we could determine that serum deprivation promoted PKCb1-PANC1 arrest in the G1 phase of the cell cycle (cells in G0/G1: 86.7±1.0% vs 45.5±0.8% in pMTH-PANC1, p&lt;0.05). Moreover, the overexpression of PKCb1 reduced the in vitro invasive capacity using Matrigel coated transwells (cells x 10 microscopic x400 fields: 2.22±0.9 vs 10.10±2.6 in pMTH-PANC1, p&lt;0.05). This behavior could be associated with a significant inhibition of secreted proteases activity (uPA: 4.11±0.8 vs 12.32±4.1 IU/mg/24h in pMTH-PANC1, p&lt;0.05 and MMP-9: 15.24±0.03 vs 24.89±2.6 AU/mg in pMTH-PANC1, p&lt;0.05). When control and PANC1-PKCb1 cells were s.c. inoculated into nude mice it was observed that PKCb1 cells were almost unable to grow and form tumors while vector-transfected cells retained this ability. In sum, our results suggest that PKCb1 overexpression in human pancreatic tumor cells PANC1 induced a less malignant phenotype both in vivo and in vitro.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 232. doi:1538-7445.AM2012-232
Abstract 233: Polo-like kinase 1 facilitates loss of Pten-induced prostate cancer formation
Authors: Liu X. Shawn , Song Bing , Elzey Bennett D. , Ratliff Timothy L. , Konieczny Stephen F. , Cheng Liang , Liu Xiaoqi 
Published: August 2012

Abstract
Loss of the tumor suppressor Pten (phosphatase and tensin homolog deleted on chromosome 10) is thought to mediate the majority of prostate cancers, but the molecular mechanism remains elusive. In this study, we demonstrate that Pten-depleted cells suffer from mitotic stress, and that nuclear function of Pten, but not its phosphastase activity, is required to reverse this stress phenotype. Further, depletion of Pten results in elevated expression of Polo-like kinase 1 (Plk1), a key regulator of the cell cycle. We found that elevated Plk1 is critical for Pten-depleted cells to adapt to mitotic stress for survival, and that re-introduction of wild-type Pten into Pten-null prostate cancer cells reduces the survival dependence on Plk1. We further show that Plk1 confers the tumorigenic competence of Pten-deleted prostate cancer cells in a mouse xenograft model. In order to evaluate the clinical relevance of our finding, we examined the expression level of Plk1 in human prostate cancer tissue assay which includes normal tissue samples, prostate hyperplasia samples and malignant tumor samples. A correlation between overexpression of Plk1 and genetic inactivation of Pten was observed during prostate neoplasia formation. These findings identify a role of Plk1 in facilitating loss of Pten-induced prostate cancer formation, which suggests that Plk1 might be a promising target for prostate cancer patients with inactivating Pten mutations.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 233. doi:1538-7445.AM2012-233