bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 1599: Radiosensitization of GBM by a novel peptidomimetic of the Second Mitochondria-derived Activator of Caspases (SMAC).
Authors: Cerna David , Carter Donna , Takebe Naoko , Coleman C. Norman , Ahmed Mansoor M. , Yoo Stephen
Published: August 2014

TL32711 is a novel small molecule peptidomimetic of the SMAC (Second Mitochondria-derived Activator of Caspases) that promotes caspase activation in the cytochrome c/Apaf-1/caspase-9 pathway. Normally SMAC is located in the mitochondria; however it is released into the cytosol when cells undergo apoptosis. Release into the cytosol and cleavage of SMAC promotes caspase-9 activation by binding to inhibitors of apoptosis proteins, IAPs. Removing the inhibitory activity of IAPs increases cells’ sensitivity to apoptotic stimuli and abrogates NF-κB survival signaling. Thus, by targeting and eliminating IAPs, SMAC mimetics re-activate death signals in cancer cells, inhibit resistance mechanisms and induce tumor death by apoptosis.

This study was undertaken to determine radiation sensitization potential of TL32711 in GBM using in vitro and in vivo approaches. TL32711 alone did not cause any killing effects in GBM cells. However, in vitro apoptosis was increased when TL32711 was combined with radiation in GBM cell lines. In vivo data demonstrated that TL32711 alone delayed the growth of implanted xenograft tumors that were further delayed when combined with radiation. The survival of mice was greatly increased in TL32711 plus radiation treated GBM intracranial orthotopic model when compared to TL32711 or radiation treatment alone. Mechanistically, TL32711 confers radiation sensitization by abrogating NFκB activity that is elevated by radiation-induced TNF-α. Taken together, this is the first report that provides strong evidence that TL32711 in combination with ionizing radiation has potential to increase the effectiveness of radiotherapy.

Funded by NCI Contract No. HHSN261200800001E.

Citation Format: David Cerna, Donna Carter, Naoko Takebe, C. Norman Coleman, Mansoor M. Ahmed, Stephen Yoo. Radiosensitization of GBM by a novel peptidomimetic of the Second Mitochondria-derived Activator of Caspases (SMAC). [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1599. doi:10.1158/1538-7445.AM2013-1599
Abstract 1626: The impact on tumor-stromal interactions of loss of collagen XV from the basement membrane zone.
Authors: Clementz Anthony G. , Mutolo Michael , Harris Ann
Published: August 2014

Most clinical therapeutics used to date depend on specific targeting of cellular components to treat cancers. However, the environment outside the tumor cell is also critical since it may provide new targets to treat malignant and resistant cancers, independent of the tumor.

We aim to target the early stages of cancer, prior to metastasis by determining the role of a non-fibrillar collagen (Type XV) and its interactions with the tumor stroma and extracellular environment.

Type XV collagen (COLXV) is found in basement membrane zones where it assumes

a pretzel-like structure but unlike the majority of fibrillar collagens does not form tight lattice networks surrounding the cell. In aggressive cancers, including breast, pancreas, ovarian and melanomas, Loss of COLXV precedes basement membrane invasion and metastasis.

Moreover, the loss of COLXV from the distal side of basement membrane zones and the resulting deficit in its interactions with other proteins may determine its specific function in tumor progression and eventual metastasis. In this context we have identified critical collagen-binding cell surface receptors on the tumor cell, which interact with COLXV and appear to mediate its functions. A number of these interacting proteins show altered signaling in cancer. We previously showed that over-expression of COLXV in cervical cancer cells alters the growth properties of these cells in vitro and that type XV collagen is a dose-dependent suppressor of tumorigenicity in vivo. We now show that over-expression of COLXV inhibits epithelial to mesenchymal transition (EMT) in vitro through interactions with cell surface receptors and has a dramatic effect on the associated signaling events and alterations on the tumor cell periphery.

Alterations in the balance of downstream signaling events may be responsible for tumor progression after the loss of COLXV. We are now further investigating the mechanisms of tumor/stroma crosstalk that are impacted by COLXV and subsequently by its depletion.

Citation Format: Anthony G. Clementz, Michael Mutolo, Ann Harris. The impact on tumor-stromal interactions of loss of collagen XV from the basement membrane zone. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1626. doi:10.1158/1538-7445.AM2013-1626
Abstract 1631: Cav1 is a key mediator of tumor-stromal interactions in melanoma.
Authors: Trimmer Casey , Capozza Franco
Published: August 2014

Several lines of experimental evidence have demonstrated the importance of the tumor microenvironment in controlling melanoma tumor growth and melanoma metastasis. Caveolin1 (Cav1), the main structural component of the plasma membrane microdomains termed Caveolae, is emerging as an important signaling molecule in the stroma of several tumor types. However, Cav1’s function in the melanoma microenvironment of primary tumors and of metastasis remains largely unexplored. Here, we devise various experimental approaches to elucidate the function of stromal Cav1 in the development of melanoma in mice. We show that loss of Cav1 (but not Cav2) in mice promotes the growth of orthotopically implanted melanoma cells. We use cocultures of fibroblasts and melanoma cells coupled with cytokine analysis to identify various Cav1 regulated factors that function in a paracrine fashion in melanoma. Cav1KO fibroblasts secrete increased amount of ShhN, bFGF, and MMP2/3, cytokines known to promote proliferation of melanoma cells and remodeling of the tumor stroma during melanomagenesis. Intradermal xenografts of fibroblasts and melanoma cells (5:1 ratios) confirmed the tumor promoting role of fibroblasts lacking Cav1. Interestingly, constitutive inhibition of the Shh pathway in melanoma cells reverses the growth and tumor-promoting effects of Cav1KO fibroblasts in co-culture or co-injection experiments suggesting a Cav1 mediated Shh heterotypic interaction between fibroblasts and melanoma cells. In summary, these studies reveal previously undefined functions for Cav1 in the melanoma microenvironment that could potentially be targeted for therapy.

Citation Format: Casey Trimmer, Franco Capozza. Cav1 is a key mediator of tumor-stromal interactions in melanoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1631. doi:10.1158/1538-7445.AM2013-1631

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.
Abstract 1639: Chondroitin sulfate proteoglycans potently inhibit invasion and serve as a central organizer of the brain tumor microenvironment.
Authors: Silver Daniel J. , Siebzehnrubl Florian A. , Schildts Michela J. , Yachnis Anthony T. , Smith George M. , Smith Amy A. , Scheffler Bjorn , Reynolds Brent A. , Silver Jerry , Steindler Dennis A.
Published: August 2014

Despite tremendous effort, glioblastoma (GBM) remains the most pervasive and lethal of all brain malignancies. One factor that contributes to this exceedingly poor prognosis is the highly invasive character of the tumor. GBM is characterized by microscopic infiltration of tumor cells throughout the otherwise healthy brain, whereas non-neural metastases, as well as select lower-grade gliomas develop as self-contained and clearly delineated lesions. Illustrated by rodent xenograft tumor models as well as pathological human patient specimens, we present evidence that one fundamental switch between these two distinct pathologies - invasion and non-invasion - is mediated through the tumor extracellular matrix (ECM). Specifically, non-invasive lesions are associated with a rich matrix containing substantial amounts of glycosylated chondroitin sulfate proteoglycans (CSPGs), whereas glycosylated CSPGs are essentially absent from diffusely infiltrative tumors. CSPGs, acting as a central organizer of the tumor microenvironment, dramatically influence resident reactive astrocytes, inducing their exodus from the tumor mass and the resultant encapsulation of non-invasive lesions. Additionally, CSPGs induce activation of tumor-associated microglia. We demonstrate that the astrogliotic barrier can directly inhibit tumor invasion, and its absence from GBM presents an environment favorable to diffuse infiltration. We also identify the LAR phosphatase receptor as a putative intermediary between extracellular CSPGs and the tumor cells themselves. In all, we present CSPGs as critical regulators of brain tumor histopathology and help to clarify the role of the tumor microenvironment in brain tumor invasion.

Citation Format: Daniel J. Silver, Florian A. Siebzehnrubl, Michela J. Schildts, Anthony T. Yachnis, George M. Smith, Amy A. Smith, Bjorn Scheffler, Brent A. Reynolds, Jerry Silver, Dennis A. Steindler. Chondroitin sulfate proteoglycans potently inhibit invasion and serve as a central organizer of the brain tumor microenvironment. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1639. doi:10.1158/1538-7445.AM2013-1639
Abstract 165: Predicting risk of colorectal cancer depending on tumor pathology features for first-degree relatives of persons with colorectal cancer.
Authors: Win Aung K. , Buchanan Daniel D. , Rosty Christophe , Giles Graham G. , Hopper John L. , Jenkins Mark A.
Published: August 2014

Background: We hypothesised that colorectal cancer (CRC) risk for relatives of persons diagnosed with CRC could be predicted by tumor molecular pathology features.

Methods: We studied a cohort of 5200 first-degree relatives (2550 women) of 792 probands with an incident invasive CRC who were recruited to the Australasian Colorectal Cancer Family Registry via population cancer registries. We excluded 32 families that were known to be Lynch syndrome. For the probands, a standardised tumor morphology review had been conducted; BRAF V600E mutation testing had been performed; and the DNA mismatch repair (MMR) status was determined by microsatellite instability and/or immunohistochemistry for MMR proteins. We calculated standardized incidence ratios (SIR) by comparing the number of CRCs observed in relatives with the number expected based on Australian incidence rates specific for age and sex. We also compared CRC risks for relatives of probands depending on the presence or absence of specific tumor pathology features.

Results: We observed 191 CRCs in relatives at mean age at diagnosis of 62.7 (SD 14.3) years and SIR was 2.14 (95% confidence interval, CI 1.85-2.48). Compared with the general population, an increased risk of CRC was observed for relatives of probands with MMR-proficient CRC (SIR 1.98, 95% CI 1.71-2.32), MMR-deficient CRC (SIR 3.60, 95% CI 2.20-6.23), rectal cancer (SIR 1.71, 95% CI 1.36-2.18), distal colon cancer (SIR 2.12, 95% CI 1.63-2.82) and proximal colon cancer (SIR 2.90, 95%CI 2.27-3.75). An increased risk of CRC was observed for relatives of probands with proximal colon cancer compared with rectal cancer (hazard ratio, HR 1.70, 95% CI 1.21-2.39, p=0.002) and for relatives of probands with MMR-deficient CRC compared with MMR-proficient CRC (HR 1.84, 95% CI 1.09-3.12, p=0.02). There was no evidence of increased risk of CRC for relatives of probands with other pathology features of CRC (tumor grade, margin, peritumoral lymphocytes, tumor infiltrating lymphocytes, Crohn-like reactions, venous invasion, BRAF mutation and contiguous adenoma) compared with those without these features.

Conclusions: First-degree relatives of persons with MMR-deficient CRC (not caused by Lynch syndrome) have a higher risk of CRC compared with first-degree relatives of persons with MMR-proficient CRC.

Citation Format: Aung K. Win, Daniel D. Buchanan, Christophe Rosty, Graham G. Giles, John L. Hopper, Mark A. Jenkins. Predicting risk of colorectal cancer depending on tumor pathology features for first-degree relatives of persons with colorectal cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 165. doi:10.1158/1538-7445.AM2013-165
Abstract 1659: Exhaustion of autophagy-mediated cell survival underlies the pre-clinical and clinical activity of chemotherapy combined with the AKT inhibitor MK-2206 in BRAF wild-type melanoma.
Authors: Rebecca Vito W. , Massaro Renato R. , Maria-Engler Silvya S. , Messina Jane L. , Gibney Geoffrey T. , Sondak Vernon K. , Kudchadkar Ragini , Smalley Keiran S.
Published: August 2014

Although targeted therapy strategies are currently lacking for patients whose melanomas are BRAF wild-type, some therapeutic efficacy was noted in a phase I clinical trial of the AKT inhibitor MK-2206 in combination with Carboplatin (C) and Paclitaxel (P). In the present study we addressed the mechanism underlying the responses to MK-2206 + CP in BRAF wild-type melanoma. As single agents, MK-2206, carboplatin and paclitaxel had only limited cytotoxic activity in both 2D and 3D cell culture and induced very little apoptosis. Prolonged treatment (>9 days) with the AKT inhibitor in combination with C+P led to significant levels of cell death in 4 3D spheroid culture models of BRAF-wild type melanoma. In contrast, treatment with single agent MK-2206 or C+P alone induced little cell death. To investigate the mechanism of interaction between these three compounds we focused upon autophagy induction. It was noted that significant levels of autophagy, as demonstrated by increased LC3-II staining, p62 expression and increased acridine orange staining, were induced following up to 6 days of treatment with the combination. In this context autophagy was protective, with levels of cell death induced by the combination significantly enhanced following treatment with the autophagy inhibitor chloroquine. The protective autophagy induced by MK-2206 + CP was only transient, with diminished levels of autophagy being observed by 9 days. The observed reduction in autophagic flux was associated with marked increases in cell death. In summary it appears that chronic insult with MK-2206 and CP pushes autophagy to its limit, relinquishing its protective role and enhancing sensitivity of the cells to therapy-induced apoptosis. These studies form the basis for a phase II trial evaluating MK-2206 in combination with chemotherapy, as well as autophagy inhibitors, in patients whose melanomas are BRAF-wild type.

Citation Format: Vito W. Rebecca, Renato R. Massaro, Silvya S. Maria-Engler, Jane L. Messina, Geoffrey T. Gibney, Vernon K. Sondak, Ragini Kudchadkar, Keiran S. Smalley. Exhaustion of autophagy-mediated cell survival underlies the pre-clinical and clinical activity of chemotherapy combined with the AKT inhibitor MK-2206 in BRAF wild-type melanoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1659. doi:10.1158/1538-7445.AM2013-1659
Abstract 1671: A genome-wide RNA interference screen identifies autophagy mediators with therapeutic implications in chronic myeloid leukemia.
Authors: Sheng Zhi , Guo Sujuan , Murphy Susan , Varmark Hanne , Virbasius Amy , Green Michael
Published: August 2014

Autophagy plays a critical role in cancer formation and therapeutic resistance. However, little is known about how autophagy is regulated in cancer and how it mediates therapeutic resistance. Here we elect to use chronic myeloid leukemia (CML) as a cancer model to study autophagy in that it is driven by a single onco-protein BCR-ABL, whose activity can be selectively blocked by imatinib a front-line treatment for CML. Moreover, imatinib resistance frequently occurs in CML patients. Thus, unraveling autophagy regulation in CML and its role in overcoming imatinib resistance has substantial therapeutic benefits not only for CML but also for other cancers that can be treated by imatinib. In this report, we performed a genome-wide RNA interference screen in K562 human CML cells using monodansylcadaverine (MDC) that marks autolysosomes followed by fluorescence-activated cell sorting to label and isolate autophagic cells. We have identified 336 candidate genes, knockdown of which significantly increased MDC fluorescence. Our further validation utilized Cyto-IDTM Green dye that selectively stains autophagy vacuoles and quantitative RT-PCR that measures knockdown efficiency of shRNAs. We have uncovered a set of genes acting as autophagy mediators in K562 cells. To study their role in imatinib resistance, we measured the effect of imatinib in combination with the knocking down of autophagy mediators. Our results showed that the shRNA of VAMP7, a pivotal factor in vesicle transportation, substantially sensitized K562 cells to imatinib. Intriguingly, our further work revealed that depletion of VAMP7 blocked the activity of key autophagy suppressors AKT and mTOR, suggesting that VAMP7 and perhaps other autophagy mediators regulate imatinib sensitivity through signaling pathways that inhibit autophagy. In conclusion, a set of genes revealed by a genome-wide RNA interference screen mediates autophagy in CML cells and, more importantly, some of these genes render CML cells resistant to imatinib thereby becoming appealing drug targets.

Citation Format: Zhi Sheng, Sujuan Guo, Susan Murphy, Hanne Varmark, Amy Virbasius, Michael Green. A genome-wide RNA interference screen identifies autophagy mediators with therapeutic implications in chronic myeloid leukemia. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1671. doi:10.1158/1538-7445.AM2013-1671
Abstract 1689: The cytoprotective role of the UPR during c-Myc dependent transformation and tumor progression.
Authors: Tameire Feven , Hart Lori S. , Qiu Bo , Koumenis Constantinos
Published: August 2014

The Unfolded Protein Response (UPR) is a conserved cellular adaptation program that is elicited due to the accumulation of unfolded proteins in the endoplasmic reticulum (ER). The PERK-pEIF2A-ATF4 arm of UPR is triggered by ER stress and primarily serves in the global attenuation of protein translation, and promotes cell survival via selective upregulation of stress induced genes. We recently showed that oncogenic Myc activation initiates UPR due to the accumulation of unfolded proteins in the ER. Using multiple genetic models, we demonstrated that ablation of UPR signaling leads to decreased cell survival in vitro and reduced tumor growth in vivo. The proto-oncogene c-Myc has been shown to activate both pro-tumorigenic and anti-tumorigenic pathways. In c-Myc driven cancers, the pro-apoptotic state is bypassed via a yet undefined pro-survival mechanism. We are interested in elucidating the role of UPR in promoting activation of pro-survival pathways during c-Myc induced tumorigenesis. We previously demonstrated that autophagy, one such pro-survival pathway, is induced and sustained during c-Myc activation in a PERK dependent manner. Moreover, genetic and pharmacological inhibition of autophagy in c-Myc induced cells decreases cell survival. Using a Qiagen Autophagy PCR Array system we screened for autophagy genes that were differentially expressed in a c-Myc dependent manner. Preliminary results indicate that several genes that regulate different steps of autophagy such as ATG9b, ATG5 and ATG16L1 are upregulated upon c-Myc induction, which was validated by qPCR. In PERK-/- MEFs, ATG5 and ATG16L1 were not upregulated and LC3B processing, a marker of autophagy induction, was significantly attenuated upon c-Myc activation. This indicates that PERK is required for the induction of autophagy genes upon c-Myc activation. To further investigate the role of the PERK-pEIF2A-ATF4 arm of UPR in cell survival during c-Myc induction, we looked at the transcription factor ATF4 which is a major downstream mediator of PERK. Using ATF4-/- MEFs, we observed significant cell death and decreased clonogenic survival upon c-Myc activation compared to ATF4+/+ MEFs. We are currently investigating how ATF4 is mediating cell survival during c-Myc induction. Our findings establish that UPR plays as an activator of pro-survival pathways such as autophagy and therefore UPR can be targeted as a therapy modality in c-Myc driven cancers.

This research is supported by NIH grant 5R01CA139362-04

Citation Format: Feven Tameire, Lori S. Hart, Bo Qiu, Constantinos Koumenis. The cytoprotective role of the UPR during c-Myc dependent transformation and tumor progression. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1689. doi:10.1158/1538-7445.AM2013-1689
Abstract 169: Temporal trends, predictors, and outcome of chemotherapy in elderly women with advanced stage endometrial cancer.
Authors: Garg Gunjal , Siddiq Zainab , Zhou Gongfu , Powell Matthew A. , Herzog Thomas , Mutch David G. , Wright Jason D.
Published: August 2014

Objective. Randomized clinical trials have suggested that adjuvant chemotherapy improves survival for women with advanced stage (III-IV) endometrial cancer. Despite the fact the endometrial cancer is common in the elderly, a minority of women >65 years of age were represented in these trials. We performed a population-based analysis to determine the use and impact on survival of adjuvant chemotherapy in elderly women with advanced stage endometrial cancer. Methods. The Surveillance Epidemiology, and End Results (SEER)-Medicare database was utilized to identify women diagnosed with stage III-IV endometrial cancer diagnosed from 1998-2007. Only those patients who had undergone a hysterectomy were included. The use of chemotherapy within 6 months of diagnosis and its impact on survival was examined using multivariable logistic regression and Cox proportional hazards models. Results. A total of 1819 women including 1193 with stage III and 626 with stage IV tumors were identified. Adjuvant chemotherapy was given to 46% of women. Use of chemotherapy increased with time from 42% in 1998 to 63% in 2007 (P<0.0001). By 2007, 54% of women with endometrioid tumors, 82% with serous tumors and 80% with carcinosarcomas received adjuvant chemotherapy. Use of whole pelvic radiotherapy decreased slightly from 40% in 1998 to 37% in 2007 while use of brachytherapy was stable at 22%. In a multivariable regression model, later year of diagnosis, non-endometrioid histology, residence in the eastern U.S., and stage IV disease were associated with receipt of chemotherapy while older women were less likely to receive chemotherapy (P<0.05). In a multivariable model including clinical and demographic characteristics women who received chemotherapy, mortality was reduced by 17% (HR=0.83; 95% CI, 0.72-0.96) compared to those who did not receive chemotherapy. Conclusion. Although the use of chemotherapy for elderly women with advanced stage endometrial cancer is increasing, fewer than half of patients >65 years of age receive chemotherapy. In addition to year of diagnosis, stage and histology are the strongest predictors of receipt of chemotherapy. Among elderly women with endometrial cancer, chemotherapy is associated with a reduction in mortality.

Citation Format: Gunjal Garg, Zainab Siddiq, Gongfu Zhou, Matthew A. Powell, Thomas Herzog, David G. Mutch, Jason D. Wright. Temporal trends, predictors, and outcome of chemotherapy in elderly women with advanced stage endometrial cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 169. doi:10.1158/1538-7445.AM2013-169
Abstract 1706: Estrogen induces stearoyl-CoA desaturase expression in human MCF-7 breast carcinoma cells.
Authors: Belkaid Anissa , Ouellette Rodney J. , Surette Marc E.
Published: August 2014

Approximately 95% of breast cancers are estrogen-dependant. Estrogen plays a crucial role in many cellular processes in estrogen-sensitive breast cancer such as carcinogenesis, production of growth factors, angiogenesis and growth stimulation. To sustain cell growth, many cancer cells exhibit an altered metabolism that is characterized by increased glycolysis and lipogenesis.

We observed for the first time an up regulation of stearoyl-CoA desaturase-1 (SCD1) in response to estrogen in the hormone-dependent MCF7 human breast carcinoma cell line. SCD1 is a key enzyme in the production of monounsaturated fatty acids that are essential for membrane biogenesis. Using estrogen-starved MCF7 cells, treatment with 2 nM of estrogen induced cell proliferation, increased SCD-1 gene expression measured by qPCR (2.6±0.1 fold increase, p<0.05) and SCD-1 protein expression (7.2 fold increase) determined by immunoblot analysis, compared to control cells. Estrogen-induced SCD1 expression was accompanied by important changes in cellular fatty acid compositions with significant increases in the monounsaturated fatty acid content in membrane phospholipids and in SCD-1 product/substrate ratios with a 4.3±0.03 fold increase in the 16:1n-7/16:0 ratio and a 1.9±0.01 fold increase in the 18:1n-9/18:0 ratio compared to untreated cells (both p<0.05). Treatment of estrogen-stimulated cells with a selective SCD1 inhibitor inhibited estrogen-induced cell proliferation and prevented the estrogen-induced changes in membrane lipid composition.

Overall, these results show for the first time that estrogen induces SCD-1 expression in breast carcinoma cells and suggests a crucial role for SCD1 in estrogen dependent cancer cell proliferation. SCD1 may therefore represent a potential therapeutic target for estrogen-dependent cancer.

(This work was supported by the Canadian Institutes of Health Research and the Canada Research Chairs Program).

Citation Format: Anissa Belkaid, Rodney J. Ouellette, Marc E. Surette. Estrogen induces stearoyl-CoA desaturase expression in human MCF-7 breast carcinoma cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1706. doi:10.1158/1538-7445.AM2013-1706
Abstract 1711: Bax delta2: A gain-of-function Bax mutant for selective chemotherapy.
Authors: Zhang Honghong , Haferkamp Bonnie , Xiang Jialing
Published: August 2014

The pro-death Bcl-2 family protein and tumor suppressor Bax is frequently mutated in tumors with microsatellite instability (MSI). Recently, we identified a novel Bax homolog, BaxΔ2, which is generated by a unique combination of mutation and alternative splicing in MSI tumors. BaxΔ2 is a potent cell death inducer. Unlike the parental Baxα, BaxΔ2 does not directly target to mitochondria, rather activates the caspase 8-mediated mitochondrial pathway. BaxΔ2-positive cancer cells are less invasive and more sensitive to a sub-set of chemotherapeutic agents. Thus, our data provide evidence that gain-of-function BaxΔ2 mutant resulted from mutation and aberrant splicing may be detrimental to tumor and thereby could be beneficial for treatment of cancer.

Citation Format: Honghong Zhang, Bonnie Haferkamp, Jialing Xiang. Bax delta2: A gain-of-function Bax mutant for selective chemotherapy. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1711. doi:10.1158/1538-7445.AM2013-1711

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.
Abstract 1712: Transmembrane domain required for MCL1 function.
Authors: Wei Guo , Wu Xiaohua , Golub Todd R.
Published: August 2014

MCL1 is an anti-apoptotic family member of the BCL2 family of proteins that exerts its anti-apoptotic function at least in large measure by sequestering BH3 domain containing pro-apoptotic proteins within the outer mitochondrial membrane. Several lines of evidence point to MCL1 as an important oncology target. MCL1 is among the top 10 most frequently amplified genes in human cancer. Consistent with its frequent amplification, MCL1 is highly expressed in many tumor types, and high expression levels of MCL1 contribute to tumor development and resistance to chemotherapy. MCL1 is required for survival of a sub-group of tumor cells that are characterized by low levels of expression of another anti-apoptotic BCL2 family protein, BCL-xL. Despite the important role of MCL1 in cancer, no inhibitors of MCL1 have reached the clinic. We employed mutagenesis to further explore the anti-apoptotic mechanism of MCL1. Deletion of the N-terminus portion of MCL1, including the PEST domain, did not significantly affect its anti-apoptotic function. However, deletion of the transmembrane (TM) domain of MCL1 abolished the anti-apoptotic function of MCL1. Furthermore, an MCL1 point mutation within the TM domain impaired its anti-apoptotic function, however, it could still bind to the pro-apoptotic proteins BIM and BAK. Therefore, the TM domain may represent an alternative site for pharmaceutical targeting of MCL1.

Citation Format: Guo Wei, Xiaohua Wu, Todd R. Golub. Transmembrane domain required for MCL1 function. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1712. doi:10.1158/1538-7445.AM2013-1712
Abstract 1727: Evidence that E2F1-mediated upregulation of Bim, a proapoptotic BH3-only protein, functions as a prosurvival molecule in cancer.
Authors: Yadav Neelu , Gogada Raghu , Liu Junwei , Tang Shaohua , Zhang Dianmu , Aldaz C Marcelo , Tang Dean , Chandra Dhyan
Published: August 2014

Proapoptotic BH3-only protein Bim plays an important role in Bax/Bak-mediated cytochrome c release and apoptosis. Here we provide evidence for a novel prosurvival function of Bim in cancer cells. Bim was constitutively overexpressed in multiple prostate and breast cancer cells as well as in primary tumor cells. Quantitative real time PCR analysis showed that Bim was transcriptionally upregulated. We have identified eight endogenous E2F1-binding sites on the Bim promoter using in silico analysis. Luciferase assay demonstrated that Bim expression was E2F1-dependent as mutation of E2F1-binding sites on the Bim promoter inhibited luciferase activities. In support, E2F1 silencing led to the loss of Bim expression in cancer cells. Bim primarily localized to mitochondrial and cytoskeleton-associated fractions. Bim-silencing or microinjection of anti-Bim antibodies into the cell cytoplasm resulted in cell rounding, detachment, and subsequent apoptosis. We observed upregulation of prosurvival proteins Bcl-xL and Mcl-1, which sequester Bim in cancer cells. In addition, phosphorylated form of Bim was also elevated in cancer cells. These findings suggest that the constitutively overexpressed Bim may function as a prosurvival molecule in epithelial cancer cells, and phosphorylation and association with Bcl-xL/Mcl-1 block its proapoptotic functions.

The prosurvival functions associated with multiple proapoptotic proteins raise the possibility that anticancer agents that only harness proapoptotic function of Bim or other BH3-only proteins may not be an efficient approach for the permeabilization of mitochondria. Our findings demonstrate that in order to induce efficient apoptosis, inhibition of prosurvival function of Bim may provide a new approach for efficient cancer therapy.

Citation Format: Neelu Yadav, Raghu Gogada, Junwei Liu, Shaohua Tang, Dianmu Zhang, C Marcelo Aldaz, Dean Tang, Dhyan Chandra. Evidence that E2F1-mediated upregulation of Bim, a proapoptotic BH3-only protein, functions as a prosurvival molecule in cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1727. doi:10.1158/1538-7445.AM2013-1727
Abstract 1729: Mitochondrial necrosis pathway drives tumor progression.
Authors: James Melissa K. , Kitsis Richard N.
Published: August 2014

Necrosis is a prominent feature of aggressive and invasive cancers. Previous clinical/epidemiological studies have suggested an association between the extent of tumor necrosis and poor prognosis and survivorship for some cancers. Evasion of apoptosis is widely accepted as a hallmark of cancer. However, whether necrotic cell death plays no role, limits, or drives carcinogenesis has not been studied in any cancer. Recent work suggests that necrosis may be an actively regulated form of cell death. In contrast to apoptosis where permeabilization of the outer mitochondrial membrane is the defining event, the central event in necrosis is the opening of a pore in the inner mitochondrial membrane termed the mitochondrial permeability transition pore (mPTP). Cyclophilin D, a peptidyl prolyl cis-trans isomerase in the mitochondrial matrix, encoded by the gene ppif, is critical for opening of the mPTP. Stable expression of ppif shRNA was used to deplete cyclophilin D in Met-1 cells, a metastatic breast cancer cell line. We first confirmed that knockdown of ppif in Met-1 cells abrogated necrosis, but not apoptosis. When these cells were transplanted into the mammary glands of wildtype FVB mice, tumors resulting from cells that express ppif shRNA were markedly smaller, with decreased volume and mass, than those derived from cells expressing control shRNA. Reconstitution of ppif knockdown cells with wild type cyclophilin D, but not an enzymatically inactive mutant, rescued tumor volume and mass. As expected, tumors arising from ppif knockdown cells exhibited less necrosis, while rates of apoptosis were unchanged. Moreover, rates of BrdU incorporation were significantly decreased in these tumors. Necrotic cell death is characterized by loss of plasma membrane integrity resulting in a marked inflammatory response. Neutrophils and macrophages recruited to tumors often secrete growth/survival/angiogenic factors that promote tumor growth and metastasis. Consistent with this model, both macrophage and neutrophil recruitment were reduced in tumors derived from ppif knockdown cells. In addition, rates of spontaneous pulmonary metastasis were markedly decreased in mice harboring tumors derived from ppif knockdown cells compared with controls. Our data suggest that, in contrast to apoptotic cell death which limits carcinogenesis, necrotic cell death actually drives disease progression by altering the tumor microenvironment. These findings may have therapeutic implications in that they suggest that inhibition - rather than promotion - of necrotic cell death may provide a novel treatment paradigm for some cancers.

Citation Format: Melissa K. James, Richard N. Kitsis. Mitochondrial necrosis pathway drives tumor progression. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1729. doi:10.1158/1538-7445.AM2013-1729
Abstract 1743: SOX10 is required for cell cycle regulation and melanomagenesis.
Authors: Cronin Julia C. , Watkins-Chow Dawn E. , Incao Art , Hasskamp Joanne H. , Schönewolf Nicola , Hayward Nicholas K. , Bastian Boris C. , Dummer Reinhard , Loftus Stacie K. , Pavan William J.
Published: August 2014

The transcription factor SOX10 is essential for proper survival and differentiation of neural crest cell lineages, and plays an important role in the establishment and maintenance of melanocytes. SOX10 is also highly expressed in melanoma tumors, however its role in the progression of the disease is not yet understood. Here, we report that melanoma tumor cell lines require wild-type SOX10 expression for proliferation, and detail the rescue of melanoma in the metabotropic glutamate receptor 1 (Grm1Tg) transgenic mouse by Sox10 haploinsufficiency. Stable SOX10 knockdown in human melanoma cells results in arrested growth, altered cellular morphology, and senescence. Cells with a stable loss of SOX10 are arrested in the G1 phase of the cell cycle with elevated cyclin-dependent kinase inhibitor 1A and 1B (p21 and p27) expression. SOX10 loss also results in hypophosphorylation of retinoblastoma protein (RB) and a reduction in the expression of its binding partner E2F1. Previously, the RB-E2F1 pathway has been shown to play a central role in cell cycle regulation, and here we demonstrate that SOX10 expression is required for the maintenance of the RB-E2F1 pathway to promote melanoma cell growth. One of the main events driving cellular transformation is the dysregulation of the cell cycle, therefore the role that SOX10 has in maintaining this process provides great promise for targeted interventions.

Citation Format: Julia C. Cronin, Dawn E. Watkins-Chow, Art Incao, Joanne H. Hasskamp, Nicola Schönewolf, Nicholas K. Hayward, Boris C. Bastian, Reinhard Dummer, Stacie K. Loftus, William J. Pavan. SOX10 is required for cell cycle regulation and melanomagenesis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1743. doi:10.1158/1538-7445.AM2013-1743
Abstract 1747: The Pax3:Foxo1a translocation product is a cell cycle-specific modifier of the alveolar rhabdomyosarcoma tumor phenotype.
Authors: Kikuchi Ken , Hettmer Simone , Aslam M. Imran , Michalek Joel E. , Laub Wolfram , Rubin Brian P. , Wagers Amy J. , Keller Charles
Published: August 2014

BACKGROUND: Rhabdomyosarcoma is the most common soft-tissue sarcoma in childhood, which falls into one of two biologically distinct subtypes, alveolar (aRMS) or embryonal rhabdomyosarcoma. aRMS harbors a translocation-mediated PAX3:FOXO1A fusion gene and has an extremely poor prognosis.

MATERIALS AND METHODS: Primary murine aRMS cultures were obtained from the Myf6Cre, Pax3:Foxo1a, p53 conditional mouse aRMS model, in which eYFP is expressed as a second cistron in the targeted Pax3:Foxo1a-ires-eYFP allele. Limited dilution transplantation experiments were performed using Pax3:Foxo1a knockdown by siRNA of eYFP or control aRMS primary cultures. To elucidate the dynamical function of Pax3:Foxo1a, time-lapse confocal microscopy experiments, cell cycle analysis, quantitative RT-PCR, western blotting, immunohistochemistry and mRNA array were performed using murine aRMS primary cell cultures with or without Pax3:Foxo1a knockdown treated by 6 Gy irradiation, or selected for ploidy using hoechst33342 sorted cell cycle-specific cells.

RESULTS: Pax3:Foxo1a is not required for tumor repopulating ability in mouse limiting-dilution transplantation experiments. The expression level of Pax3:Foxo1a was discovered to be dynamic and varied during the cell cycle in murine aRMS primary cell cultures and human aRMS cell lines. Pax3:Foxo1a is enriched in G2 and triggers a transcriptional program conducive to checkpoint adaptation in genome-wide expression analysis and quantitative RT-PCR. Radiation resulted in a higher fraction of DNA breaks amongst mitotic cells (as represented by dual pHH3 positive, H2AX positive cells) under conditions of Pax3:Foxo1a expression compared with knockdown, suggesting that Pax3:Foxo1a facilitates G2/M transit, consistent with checkpoint adaptation.

CONCLUSION: We demonstrated that Pax3:Foxo1a does not function in tumor cell maintenance, the expression level of Pax3:Foxo1a is dynamic and varies during the cell cycle, and Pax3:Foxo1a facilitates checkpoint adaptation under stress conditions such as irradiation. Furthermore, the surprisingly dynamic regulation of the Pax3:Foxo1a locus is a paradigm that has important implications for the way in which oncogenes are modeled in cancer biology.

Citation Format: Ken Kikuchi, Simone Hettmer, M. Imran Aslam, Joel E. Michalek, Wolfram Laub, Brian P. Rubin, Amy J. Wagers, Charles Keller. The Pax3:Foxo1a translocation product is a cell cycle-specific modifier of the alveolar rhabdomyosarcoma tumor phenotype. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1747. doi:10.1158/1538-7445.AM2013-1747
Abstract 1769: Real-time imaging demonstrates cancer cells exposed to UV irradiation either repair their DNA or die.
Authors: Miwa Shinji , Yano Shuya , Hiroshima Yukihiko , Tome Yasunori , Uehara Fuminori , Mii Sumiyuki , Kimura Hiroaki , Hayashi Katsuro , Tsuchiya Hiroyuki , Efimova Elena , Digman Michelle , Gratton Enrico , Hoffman Robert M.
Published: August 2014

The DNA repair protein 53BP1 is re-localized in foci after DNA damage. In this study, we imaged the real-time response of 53BP1 linked to GFP to DNA damage induced by UV irradiation. Inhibition of proliferation by UV irradiation was analyzed by a clonogenic assay. The relocalization of GFP fused to the chromatin-binding domain of 53BP1 was imaged after UV irradiation of MiaPaca-2 53BP1-GFP human pancreatic cancer cells. The clonogenic assay demonstrated that UVC dose-dependently inhibited cell proliferation, while UVA and UVB showed little effect. During live-cell imaging, 53BP1-GFP foci formation was observed within 30 min after UVC irradiation. High-dose UVC also induced apoptosis within 24 h after irradiation. The cells treated with UVC irradiation appear to have two different fates: DNA repair or apoptosis. A fraction of the cells underwent apoptosis, and the other fraction repaired their DNA as evidenced by 53BP1 focus formation. The present study demonstrates that some cells may repair their DNA successfully and others can not. This has important implication for UV-based photodynamic therapy.

Citation Format: Shinji Miwa, Shuya Yano, Yukihiko Hiroshima, Yasunori Tome, Fuminori Uehara, Sumiyuki Mii, Hiroaki Kimura, Katsuro Hayashi, Hiroyuki Tsuchiya, Elena Efimova, Michelle Digman, Enrico Gratton, Robert M. Hoffman. Real-time imaging demonstrates cancer cells exposed to UV irradiation either repair their DNA or die. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1769. doi:10.1158/1538-7445.AM2013-1769
Abstract 177: Inhibition of the autotaxin-lysophosphatidic acid (ATX-LPA) pathway for chemoprevention of hepatocellular carcinoma.
Authors: Wei Lan , Hoshida Yujin , Bain Gretchen , Swaney Jamie , Lauwers Gregory Y. , Schaefer Esperance A. , Yamada Suguru , Lanuti Michael , Chung Raymond T. , Tanabe Kenneth K. , Fuchs Bryan C.
Published: August 2014

Background: Hepatocellular carcinoma (HCC) is increasing in incidence both in the United States and worldwide. Due to the limited treatment options for HCC, prevention in high-risk patients with cirrhosis has been proposed as an alternative strategy. Aberrant activation of the autotoxin-lysophosphatidic acid (ATX-LPA) pathway, an upstream activator of RhoA signaling, has been associated with fibrosis in several organs. Here, we hypothesized that inhibition of the ATX-LPA pathway in fibrotic liver would reduce progression to cirrhosis and HCC occurrence. Methods: Rats were treated weekly with 50 mg/kg diethylnitrosamine (DEN) to induce sequential development of fibrosis, cirrhosis and HCC. After establishment of liver fibrosis (8 weeks), rats were treated daily by oral gavage with either vehicle control, 5 mg/kg AM063 (an ATX inhibitor) or 30 mg/kg AM095 (a LPA receptor 1 (LPA1) antagonist). At the end of the study, rats were sacrificed, livers were sectioned and stained to analyze disease progression, and tumor nodules were counted. In addition, the effect of LPA on RhoA signaling was investigated in hepatic stellate cell lines (TWNT4 and LX-2). Results: Gene set enrichment analysis revealed that a RhoA activation gene signature, which was associated with poor prognosis in human cirrhosis patients, increased in DEN-injured rat livers. Several members of this gene signature, including pro-fibrogenic connective tissue growth factor (CTGF), were reduced after treatment with either AM063 or AM095. In addition, both AM063 and AM095 significantly (p < 0.01) prevented the development of HCC tumor nodules in DEN-injured livers from a median of 16 in controls to a median of 8 and 6 in AM063 and AM095-treated rats, respectively. Interestingly, the extent of fibrosis in DEN-injured rat livers as measured by Ishak score also significantly (p < 0.01) decreased from a median of 6 in controls to a median of 4 in both AM063 and AM095-treated rats. Examination of hepatic stellate cell lines revealed that LPA increased RhoA-mediated CTGF expression, which was inhibited by AM095. Conclusions: We have identified the ATX-LPA pathway as a major mediator of liver fibrosis progression. Further, AM063 and AM095 are potential chemoprevention strategies for HCC.

Citation Format: Lan Wei, Yujin Hoshida, Gretchen Bain, Jamie Swaney, Gregory Y. Lauwers, Esperance A. Schaefer, Suguru Yamada, Michael Lanuti, Raymond T. Chung, Kenneth K. Tanabe, Bryan C. Fuchs. Inhibition of the autotaxin-lysophosphatidic acid (ATX-LPA) pathway for chemoprevention of hepatocellular carcinoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 177. doi:10.1158/1538-7445.AM2013-177