Abstract P5-06-05: Palmitate induces a senescent-like phenotype in fibroblasts resulting in altered phenotypes in cells of the breast tumor microenvironment

Background: Obese breast cancer patients face a worse prognosis, including an increased risk of recurrence and mortality. While the causative mechanisms have yet to be fully uncovered, emerging evidence implicates palmitate, increased in the obese state, in development of cellular senescence, an inflammatory state associated with proliferation, metastasis, and tumor-associated neutrophil (TAN) polarization, among other measures of carcinogenesis. However, studies have yet to investigate the impact of palmitate on induction of senescence in breast fibroblasts, and no studies have assessed the effect of senescent fibroblasts on neutrophil polarization in the breast tumor microenvironment. This said, we hypothesize that palmitate alters breast cancer cell gene expression and neutrophil phenotype via induction of a senescent-like phenotype in fibroblasts. Methods: HCA2, IMR-90, and human mammary fibroblasts were exposed to palmitate or vehicle in media supplemented with 2% charcoal-stripped fetal bovine serum, after which the cells were measured through qPCR for expression of IL-1a, IL-6 and IL-8, some of the most prominent members of the senescence-associated secretory phenotype. Palmitate-exposed fibroblasts were also subjected to chromogenic staining for senescence-associated beta-galactosidase and immunoenzymatic BrdU analysis, two well-established measures of senescence. Next, in order to study the influence of these fibroblasts on other cells of the breast tumor microenvironment, we assessed their impact on polarization of DMSO-differentiated HL-60 neutrophils by using flow cytometry to measure neutrophil expression of CD54 and CD95, differentially expressed on N1 and N2 neutrophils. Finally, we employed PCR arrays to assess the impact of palmitate-exposed fibroblasts on the expression of 84 genes in MCF-7 and 231 breast cancer cells, measuring activation of pathways related to apoptosis, cell cycle, DNA damage, senescence, telomere maintenance, metabolism, angiogenesis, and the endothelial-to-mesenchymal transition. Results and Conclusions: Palmitate induced pro-inflammatory gene expression and SA-beta-gal activity and decreased BrdU incorporation in fibroblasts. Palmitate also exhibited non-cell-autonomous effects, as palmitate-exposed fibroblasts induced phenotypic changes in both neutrophils and breast cancer cells. These findings are among the first to implicate palmitate-induced fibroblast senescence in the stimulation of non-cell-autonomous changes in the breast tumor microenvironment and will ultimately inform our understanding of the mechanistic connection between the obesity-associated factor palmitate and breast tumorigenesis.

Citation Format: Brittany Susanne Harlow, Albert Davalos, Bryan McClellan, Andrew Brenner, Christopher Jolly, Stefano Tiziani, Steve Hursting, Linda deGraffenried. Palmitate induces a senescent-like phenotype in fibroblasts resulting in altered phenotypes in cells of the breast tumor microenvironment [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-06-05.

MMP1 drives tumor progression in large cell carcinoma of the lung through fibroblast senescence

Large cell carcinoma (LCC) is a rare and aggressive lung cancer subtype with poor prognosis and no targeted therapies. Tumor-associated fibroblasts (TAFs) derived from LCC tumors exhibit premature senescence, and coculture of pulmonary fibroblasts with LCC cell lines selectively induces fibroblast senescence, which in turn drives LCC cell growth and invasion. Here we identify MMP1 as overexpressed specifically in LCC cell lines, and we show that expression of MMP1 by LCC cells is necessary for induction of fibroblast senescence and consequent tumor promotion in both cell culture and mouse models. We also show that MMP1, in combination with TGF-β1, is sufficient to induce fibroblast senescence and consequent LCC promotion. Furthermore, we implicate PAR-1 and oxidative stress in MMP1/TGF-β1-induced TAF senescence. Our results establish an entirely new role for MMP1 in cancer, and support a novel therapeutic strategy in LCC based on targeting senescent TAFs.

Abstract PS19-13: Palmitate exacerbates breast tumorigenesis in vitro via induction of a senescent-like phenotype in fibroblasts

Background: Obesity is associated with a worse breast cancer prognosis, conferring an increased risk of recurrence and mortality. At the same time, recent evidence suggests that obesity is also correlated with development of cellular senescence, an inflammatory state associated with exacerbation of breast tumorigenesis in preclinical models. As obese individuals present greater levels of inflammation at baseline, research efforts are warranted to examine the means by which obesity promotes the development of a senescent phenotype, which may further exacerbate inflammation. Additionally, studies have yet to determine whether obesity-induced senescence modulates the tumorigenic process in the context of breast cancer specifically. Methods: To this end, we exposed fibroblasts to the obesity-associated circulating factor palmitate and used qPCR and western immunoblotting to assess the expression of genes and proteins involved in the senescent state, including interleukin (IL)-1a, IL-6, IL-8, senescence-associated beta-galactosidase (SA-beta-gal), and matrixmetalloproteinase (MMP)-9. As a mechanistic investigation, we next assessed the impact of palmitate on activation of NF-kB signaling using western immunoblotting, immunofluorescence, and NF-kB luciferase reporter assays. Finally, we utilized cell counting, MTT, wound healing, and colony formation assays to examine the impact of these palmitate-exposed fibroblasts on breast cancer cell proliferation, viability, motility, and survival, respectively. Results: We found that palmitate induced fibroblast gene expression of IL-1a, IL-6, and IL-8, major components of the senescent secretome, as well as expression of the senescent markers SA-beta-gal and MMP-9. The mechanism at least partially involved activation of NF-kB, responsible for production of about 75% of senescent secretome components. More importantly, these palmitate-exposed fibroblasts were of pathological impact, exacerbating in vitro measures of breast cancer cell aggressiveness. Conclusions: These findings contribute to our understanding of the impact of obesity-associated factors on breast tumorigenesis, demonstrating a mechanistic link between palmitate and the pro-tumorigenic effects of senescent cells. Our studies will ultimately aid in the identification of a therapeutic target that can be used to improve the comparably worse outcomes of the obese breast cancer patient.

Citation Format: Brittany Susanne Harlow, Albert Davalos, Andrew Brenner, Christopher Jolly, Stefano Tiziani, Steve Hursting, Linda deGraffenried. Palmitate exacerbates breast tumorigenesis in vitro via induction of a senescent-like phenotype in fibroblasts [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS19-13.

Effect of atrial fibrillation on endovascular thrombectomy for acute ischemic stroke. A meta-analysis of individual patient data from six randomised trials: Results from the HERMES collaboration

Background

Atrial fibrillation is an important risk factor for ischemic stroke, and is associated with an increased risk of poor outcome after ischemic stroke. Endovascular thrombectomy is safe and effective in acute ischemic stroke patients with large vessel occlusion of the anterior circulation. This meta-analysis aims to investigate whether there is an interaction between atrial fibrillation and treatment effect of endovascular thrombectomy, and secondarily whether atrial fibrillation is associated with worse outcome in patients with ischemic stroke due to large vessel occlusion.

Methods

Individual patient data were from six of the recent randomised clinical trials (MR CLEAN, EXTEND-IA, REVASCAT, SWIFT PRIME, ESCAPE, PISTE) in which endovascular thrombectomy plus standard care was compared to standard care alone. Primary outcome measure was the shift on the modified Rankin scale (mRS) at 90 days. Secondary outcomes were functional independence (mRS 0–2) at 90 days, National Institutes of Health Stroke Scale score at 24 h, symptomatic intracranial hemorrhage and mortality at 90 days. The primary effect parameter was the adjusted common odds ratio, estimated with ordinal logistic regression (shift analysis); treatment effect modification of atrial fibrillation was assessed with a multiplicative interaction term.

Results

Among 1351 patients, 447 patients had atrial fibrillation, 224 of whom were treated with endovascular thrombectomy. We found no interaction of atrial fibrillation with treatment effect of endovascular thrombectomy for both primary (p-value for interaction: 0.58) and secondary outcomes. Regardless of treatment allocation, we found no difference in primary outcome (mRS at 90 days: aOR 1.11 (95% CI 0.89–1.38) and secondary outcomes between patients with and without atrial fibrillation.

Conclusion

We found no interaction of atrial fibrillation on treatment effect of endovascular thrombectomy, and no difference in outcome between large vessel occlusion stroke patients with and without atrial fibrillation.

Abstract P1-08-02: Omega-3 fatty acids modulate the ability of obese conditions to induce of a proinflammatory phenotype in fibroblasts

Background: Approximately 40% of American women suffer from obesity, and about 1 in 8 women will be diagnosed with breast cancer during her lifetime. The concurrence of these trends has the potential to be particularly detrimental, as obesity confers a worse prognosis for both pre- and postmenopausal breast cancer patients. While the precise mechanisms by which obesity impacts breast cancer prognosis remain to be discovered, evidence suggests that obesity upregulates components of cancer-associated fibroblast (CAF) and senescent cell secretomes, both causally associated with carcinogenesis. Specifically, obesity has been shown to induce expression of the secretory products prostaglandin E2, high mobility group protein B1, interleukin (IL)-6, IL-1 beta, and matrix metalloproteinase-1, the expression of which can be modulated by omega-3 fatty acid-induced signaling. However, studies have yet to determine whether obesity imparts these proinflammatory phenotypes in any individual cell type in the breast tumor microenvironment as well as whether these phenotypes can be modulated by administration of omega-3 fatty acids. This said, we hypothesize that fatty acids modulate the ability of obese conditions to induce a proinflammatory senescent- or CAF-like fibroblast phenotype and thus impact breast cancer progression. Because fibroblasts constitute 80% of the tumor stromal mass, it is of the utmost importance to study obesity-stimulated changes in this cellular compartment and their effects on tumor progression.

Methods: Fibroblasts were exposed to sera derived from lean or obese women with and without omega-3 fatty acid supplementation and assessed for changes in expression of proinflammatory genes, including IL-1α, IL-6, and IL-8, as well as nuclear localization of p65, a subunit of the NF-kB transcription factor, which transcribes about 75% of genes related to the senescent secretome. Conditioned media (CM) from these fibroblasts were then applied to breast cancer cells to assess measures of cancer cell aggressiveness. Finally, as an ex vivo study, breast tissue samples from lean and obese women and mice were compared for concentration of proinflammatory, senescent fibroblasts by immunohistochemical analyses.

Results: Gene and protein expression analyses demonstrated that obese conditions induced a proinflammatory phenotype in fibroblasts, an effect at least partially modulated by omega-3 fatty acids. These phenotypic changes were not without pathological consequence: CM from obesity-stimulated fibroblasts impacted in vitro measures of breast cancer cell aggressiveness to a greater degree than lean sera-stimulated fibroblasts.

Conclusions: While correlative, these data contribute to the identification of a link between obesity and proinflammatory, senescent phenotypes and will ultimately allow for elucidation of the means by which obese conditions confer a worse prognosis for breast cancer patients. In addition, these findings will contribute to our understanding of crosstalk within the tumor microenvironment and inform our pursuit for the development of novel therapeutic targets.

Citation Format: Brittany Harlow, Albert Davalos, Andrew Brenner, Christopher Jolly, Stefano Tiziani, Stephen Hursting, Linda deGraffenried. Omega-3 fatty acids modulate the ability of obese conditions to induce of a proinflammatory phenotype in fibroblasts [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-08-02.

Abstract 466: Cellular senescence drives skin carcinogenesis

Squamous cell carcinoma (SCC) is the second most common non-melanoma skin cancer, and has a high rate of recurrence and metastasis. Systemic genotoxic chemotherapeutic drugs such as doxorubicin (Doxo) can be used to treat SCC, but these agents can have deleterious long-term side effects, including fueling the development of more aggressive cancers. Some of the adverse effects of genotoxic chemotherapies might be due to their ability to induce cellular senescence. Cellular senescence is a tumor suppressive mechanism that entails a permanent cell growth arrest accompanied by several metabolic changes. Senescent cells increase during aging, and accumulating evidence suggests they can contribute to a variety of age related pathologies, including cancer, by secreting numerous pro-inflammatory molecules, growth factors and proteases, a feature termed the senescence-associated secretory phenotype (SASP). We recently showed that genotoxic and cytotoxic chemotherapeutic agents induce senescence and a SASP in vivo. However, a direct role for senescent cells in skin carcinogenesis in vivo remains unexplored. To investigate the role of senescent cells and the SASP in squamous cell skin carcinogenesis, we first induced senescence with Doxo in p16-3MR transgenic mice. These mice are designed to permit the selective elimination of senescent cells expressing the established senescence marker p16INK4a (p16) by administrating ganciclovir (GCV) which has a high affinity for the herpes simplex viral thymidine kinase (HSV-TK). Phosphorylated GCV is a DNA chain terminator that kills HSV-TK expressing cells by apoptosis. After Doxo treatment, we initiated skin SCC in p16-3MR mice with 7, 12-dimethylbenz[a]anthracene (DMBA), followed by treatment with 12-O-Tetradecanoylphorbol-13-acetate (TPA) to promote skin carcinogenesis. 25 weeks after Doxo treatment, we observed a significant increase in p16 mRNA levels as well as an increase in expression of the SASP factors IL-1α, MMP-9, and IL-17 in the skin of Doxo- compared to PBS- treated mice. Further, the presence of senescent cells resulted in significantly larger and more proliferative tumors compared to PBS-treated mice. Importantly, systemic elimination of Doxo-induced senescent cells using GCV reduced the expression of SASP factors and significantly reduced tumor size, suggesting that senescent cells fuel skin tumor progression. These findings will help our understanding of the role of chemotherapy-induced cellular senescence in skin carcinogenesis and will pave the way for developing novel therapeutics against squamous cell carcinoma and the deleterious side effects of genotoxic chemotherapies.

Citation Format: Fatouma Alimirah, Alexis Valdovinos, Emily Chang, Sena Alptekin, Tanya Pulido, Elijah Jones, Chandani Limbad, Michael Velarde, Marco Demaria, Albert Davalos, Judith Campisi. Cellular senescence drives skin carcinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 466.

Abstract 5131: Obese conditions induce changes in stromal fibroblast phenotype

Background: Over 40% of American women present a BMI ≥30, which is particularly alarming since obesity confers a worse prognosis for both pre- and postmenopausal breast cancer patients. Although the molecular mechanisms behind this remain unclear, obese conditions have been shown to upregulate certain components of the cancer-associated fibroblast (CAF) secretome and senescence associated secretory phenotype (SASP), both directly correlated with tumorigenesis. However, studies have yet to determine whether obesity induces a cohesive SASP or CAF-like phenotype from any one cell type of the breast tumor microenvironment. Because fibroblasts represent the most common breast tumor cell type, it is of particular importance to investigate obesity-induced changes in this cellular compartment and their effects on cancer cell behavior. Methods: Direct effects of obesity were examined by exposing IMR-90 and HCA2 human fibroblasts to media supplemented with 2% sera from obese women and measuring changes in gene and protein expression, while indirect effects were evaluated by exposing the fibroblasts to conditioned media (CM) from obesity-stimulated MCF-7 and T47D cells and assessing changes in expression of proinflammatory cytokines. Breast cancer cells were also exposed to CM from obesity-stimulated fibroblasts and measured for changes in proliferation, survival, motility, and invasion. Results and Conclusions: Obese conditions induced proinflammatory changes in fibroblasts both directly and indirectly and stimulated changes in the paracrine signaling between fibroblasts and breast cancer cells. These data contribute to the growing evidence implicating obesity in the promotion of breast cancer progression. Additionally, these findings provide a new line of research to develop potential therapeutic targets to improve outcome.

Citation Format: Brittany Harlow, Albert Davalos, Andrew Brenner, Christopher Jolly, Stephen Hursting, Linda deGraffenried. Obese conditions induce changes in stromal fibroblast phenotype [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5131.

Heterotypic paracrine signaling drives fibroblast senescence and tumor progression of large cell carcinoma of the lung

Senescence in cancer cells acts as a tumor suppressor, whereas in fibroblasts enhances tumor growth. Senescence has been reported in tumor associated fibroblasts (TAFs) from a growing list of cancer subtypes. However, the presence of senescent TAFs in lung cancer remains undefined. We examined senescence in TAFs from primary lung cancer and paired control fibroblasts from unaffected tissue in three major histologic subtypes: adenocarcinoma (ADC), squamous cell carcinoma (SCC) and large cell carcinoma (LCC). Three independent senescence markers (senescence-associated beta-galactosidase, permanent growth arrest and spreading) were consistently observed in cultured LCC-TAFs only, revealing a selective premature senescence. Intriguingly, SCC-TAFs exhibited a poor growth response in the absence of senescence markers, indicating a dysfunctional phenotype rather than senescence. Co-culturing normal fibroblasts with LCC (but not ADC or SCC) cancer cells was sufficient to render fibroblasts senescent through oxidative stress, indicating that senescence in LCC-TAFs is driven by heterotypic signaling. In addition, senescent fibroblasts provided selective growth and invasive advantages to LCC cells in culture compared to normal fibroblasts. Likewise, senescent fibroblasts enhanced tumor growth and lung dissemination of tumor cells when co-injected with LCC cells in nude mice beyond the effects induced by control fibroblasts. These results define the subtype-specific aberrant phenotypes of lung TAFs, thereby challenging the common assumption that lung TAFs are a heterogeneous myofibroblast-like cell population regardless of their subtype. Importantly, because LCC often distinguishes itself in the clinic by its aggressive nature, we argue that senescent TAFs may contribute to the selective aggressive behavior of LCC tumors.

Thrombolysis and thrombectomy in patients treated with dabigatran with acute ischemic stroke: Expert opinion

Systemic thrombolysis with rt-PA is contraindicated in patients with acute ischemic stroke anticoagulated with dabigatran. This expert opinion provides guidance on the use of the specific reversal agent idarucizumab followed by rt-PA and/or thrombectomy in patients with ischemic stroke pre-treated with dabigatran. The use of idarucizumab followed by rt-PA is covered by the label of both drugs.

Abstract 4103: Cancer cell-stromal cell crosstalk drives fibroblast senescence and tumor progression in large cell carcinoma of the lung in culture and in vivo

Permanent cell cycle arrest through senescence has been previously regarded as a protective mechanism against tumor progression. In contrast, there is evidence that senescence in tumor-associated fibroblasts (TAFs) enhances tumor growth. Senescence has been reported in tumor associated fibroblasts (TAFs) from a growing list of selected cancer types. However, the presence of senescent TAFs in lung cancer remains undefined. To address this gap of knowledge, we examined common markers of senescence in primary TAFs from the 3 major non-small cell lung cancer (NSCLC) subtypes: adenocarcinoma (ADC), squamous cell carcinoma (SCC) and large cell carcinoma (LCC). Given the difficulties in gathering LCC-TAFs owing to the lower prevalence of LCC compared to the other subtypes, primary fibroblasts from 2 independent cell collections were used. We found an enrichment of the myofibroblast-like phenotype in TAFs regardless their histologic subtype, yet senescence was observed in LCC-TAFs only. Likewise, co-culturing normal lung fibroblasts with LCC (but not ADC or SCC) cancer cells was sufficient to induce senescence, and this induction was prevented in the presence of an antioxidant, indicating that it is mediated through oxidative stress. Of note, senescent fibroblasts provided growth and invasive advantages to LCC cells in culture and in vivo beyond those provided by control (non-senescent) fibroblasts. These results expand recent evidence that challenges the common assumption that lung TAFs are a heterogeneous myofibroblast-like cell population regardless their histologic subtype. Of note, because LCC often distinguishes itself in the clinic by its aggressive nature, our findings support that senescent or senescent-like TAFs may contribute to the selective aggressive behavior of LCC tumors.

Citation Format: Roberto Lugo, Marta Gabasa, Francesca Andriani, Marta Puig, Federica Facchinetti, Josep Ramírez, Abel Gómez-Caro, Ugo Pastorino, Pere Gascón, Albert Davalos, Noemí Reguart, Luca Roz, Jordi Alcaraz. Cancer cell-stromal cell crosstalk drives fibroblast senescence and tumor progression in large cell carcinoma of the lung in culture and in vivo. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4103.

Mechanical Thrombectomy for Isolated M2 Occlusions: A Post Hoc Analysis of the STAR, SWIFT, and SWIFT PRIME Studies

BACKGROUND AND PURPOSE

Mechanical thrombectomy is beneficial for patients with acute ischemic stroke and a proximal anterior occlusion, but it is unclear if these results can be extrapolated to patients with an M2 occlusion. The purpose of this study was to examine the technical aspects, safety, and outcomes of mechanical thrombectomy with a stent retriever in patients with an isolated M2 occlusion who were included in 3 large multicenter prospective studies.

MATERIALS AND METHODS

We included patients from the Solitaire Flow Restoration Thrombectomy for Acute Revascularization (STAR), Solitaire With the Intention For Thrombectomy (SWIFT), and Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment (SWIFT PRIME) studies, 3 large multicenter prospective studies on thrombectomy for ischemic stroke. We compared outcomes and technical details of patients with an M2 with those with an M1 occlusion. All patients were treated with a stent retriever. Imaging data and outcomes were scored by an independent core laboratory. Successful reperfusion was defined as modified Thrombolysis in Cerebral Infarction score of 2b/3.

RESULTS

We included 50 patients with an M2 and 249 patients with an M1 occlusion. Patients with an M2 occlusion were older (mean age, 71 versus 67 years; P = .04) and had a lower NIHSS score (median, 13 versus 17; P < .001) compared with those with an M1 occlusion. Procedural time was nonsignificantly shorter in patients with an M2 occlusion (median, 29 versus 35 minutes; P = .41). The average number of passes with a stent retriever was also nonsignificantly lower in patients with an M2 occlusion (mean, 1.4 versus 1.7; P = .07). There were no significant differences in successful reperfusion (85% versus 82%, P = .82), symptomatic intracerebral hemorrhages (2% versus 2%, P = 1.0), device-related serious adverse events (6% versus 4%, P = .46), or modified Rankin Scale score 0-2 at follow-up (60% versus 56%, P = .64).

CONCLUSIONS

Endovascular reperfusion therapy appears to be feasible in selected patients with ischemic stroke and an M2 occlusion.

Impact of age and baseline NIHSS scores on clinical outcomes in the mechanical thrombectomy using solitaire FR in acute ischemic stroke study

BACKGROUND AND PURPOSE

Age and stroke severity are inversely correlated with the odds of favorable outcome after ischemic stroke. A previously proposed score for Stroke Prognostication Using Age and NIHSS Stroke Scale (SPAN) indicated that SPAN-100-positive patients (ie, age + NIHSS score = 100 or more) do not benefit from IV-tPA. If this finding holds true for endovascular therapy, this score can impact patient selection for such interventions. This study investigated whether a score combining age and NIHSS score can improve patients' selection for endovascular stroke therapy.

MATERIALS AND METHODS

The SPAN index was calculated for patients in the prospective Solitaire FR Thrombectomy for Acute Revascularization study: an international single-arm multicenter cohort for anterior circulation stroke treatment by using the Solitaire FR. The proportion with favorable outcome (90-day mRS score ≤2) was compared between SPAN-100-positive versus-negative patients.

RESULTS

Of the 202 patients enrolled, 196 had baseline NIHSS scores. Fifteen (7.7%) patients were SPAN-100-positive. There was no difference in the rate of successful reperfusion (Thrombolysis In Cerebral Infarction 2b or 3) between SPAN-100-positive versus -negative groups (93.3% versus 82.8%, respectively; P = .3). Stroke SPAN-100-positive patients had a significantly lower proportion of favorable clinical outcomes (26.7% versus 60.8% in SPAN-100-negative, P = .01). In a multivariable analysis, SPAN-100-positive status was associated with lower odds of favorable outcome (OR, 0.3; 95% CI, 0.1-0.9; P = .04). A higher baseline Alberta Stroke Program Early CT Score and a short onset to revascularization time also predicted favorable outcome in the multivariable analysis.

CONCLUSIONS

A significantly lower proportion of patients with a positive SPAN-100 achieved favorable outcome in this cohort. SPAN-100 was an independent predictor of favorable outcome after adjusting for time to treatment and the extent of preintervention tissue damage according to the Alberta Stroke Program Early CT Score.

Polyphenols and cardiovascular disease: a critical summary of the evidence

Epidemiological studies are clear: diets in which plant foods provide the major portion of caloric intake, e.g. the Mediterranean and the Japanese diets, are associated with a reduced risk of certain degenerative diseases like cancer and atherosclerosis. Although fats and proteins in plants, as opposed to those of animal origin, are responsible to some extent for these protective effects, the contribution of other plant food components may also be relevant. In the past few years, research on polyphenols has remarkably expanded and is unveiling several biological activities of these compounds. Alas, the marketing departments of several industries are jumping ahead of solid scientific evidence; as a consequence, unsubstantiated claims are being made and whole foods or fortified, enriched, or enhanced foods are being created and sold. Science is beginning to corroborate some of these claims, but much more research is needed and several myths are to be disproven. In this mini-review we critically discuss the current limitations of polyphenol research and we contend that, in addition to their putative antioxidant action, several biochemical and physiological processes might be influenced by polyphenols.

Abstract 4507: Small molecule inhibitor of MDM2 induces p53-dependent HMGB1 secretion followed by apoptosis in cancer cells and incomplete senescence in normal fibroblasts

An attractive therapeutic approach against cancers with wild-type (wt) p53 is the emergent class of small molecule MDM2 inhibitors, including the imidazoline nutlin-3 and more potent spiro-oxindole MI-63 (Ascenta Therapeutics). Both can rapidly increase intracellular p53wt levels and induce apoptosis or a senescence growth arrest, depending on the neoplastic status of the target cell. A critical question in the clinical development of such MDM2 inhibitors is their potential for normal tissue toxicity. In the absence of MDM2, p53 activation can cause fatal normal tissue pathology; and MDM2 inhibition can induce p53-dependent cell senescence in mouse fibroblasts. To assess the effects of MI-63 effects in human cells, we compared treatment (2.5-10 uM, 1-7 d) responses in p53wt malignant human mammary epithelial cells (MCF7) with those of p53wt normal human foreskin fibroblasts (HCA2). As expected, MI-63 had little effect on p53mut human cancer cells (MDA-231). However, against p53wt cancer cells and fibroblasts, MI-63 produced a dose-dependent increase in both nuclear p53 levels and reporter gene (p21) expression within 24 h. MCF7 cells responded with a dose- and time-dependent increase in apoptosis after 2 d exposure (vital dye uptake, cleaved PARP). By contrast, HCA2 cells responded with partially reversible growth arrest and a senescent-like phenotype (increased ROS, SOD2, and SA-βgal) within 3 days. A common early (24 h) MI-63 response by both the malignant and normal cells was nuclear loss of high-mobility group box-1 protein (HMGB1) associated with its active extracellular secretion. Acetylation of this damage-reporting cytokine, thought to be required for its secretion, was detected by western and mass spectrometry analyses. Although HMGB1 is generally pro-inflammatory and may be a harbinger of the senescence-associated secretory phenotype (SASP), MI-63 treated fibroblasts failed to exhibit induction of DNA damage foci or other features characteristic of SASP including IL-6 secretion. Surprisingly, MI-63 treatment of HCA2 beginning 24 or 48 h after a senescence-inducing dose of ionizing radiation (10 Gy) prevented enlarged cell morphology and produced a &gt;80% reduction in SASP associated IL-6 secretion. These findings indicate that upregulation of p53wt in proliferating fibroblasts by MI-63, in the absence of DNA damage or other cell stresses, induces an incomplete senescence like growth arrest without a SASP response, consistent with our finding that p53 restrains SASP. In contrast, MI-63 upregulation of p53wt in malignant epithelial cells caused apoptotic cell death. The early release of HMGB1 from these dying cancer cells may modulate host innate immune response and/or recruit tumor infiltrating inflammatory cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4507. doi:10.1158/1538-7445.AM2011-4507

Zinc-finger protein-targeted gene regulation: genomewide single-gene specificity

Zinc-finger protein transcription factors (ZFP TFs) can be designed to control the expression of any desired target gene, and thus provide potential therapeutic tools for the study and treatment of disease. Here we report that a ZFP TF can repress target gene expression with single-gene specificity within the human genome. A ZFP TF repressor that binds an 18-bp recognition sequence within the promoter of the endogenous CHK2 gene gives a >10-fold reduction in CHK2 mRNA and protein. This level of repression was sufficient to generate a functional phenotype, as demonstrated by the loss of DNA damage-induced CHK2-dependent p53 phosphorylation. We determined the specificity of repression by using DNA microarrays and found that the ZFP TF repressed a single gene (CHK2) within the monitored genome in two different cell types. These data demonstrate the utility of ZFP TFs as precise tools for target validation, and highlight their potential as clinical therapeutics.

WRN, the protein deficient in Werner syndrome, plays a critical structural role in optimizing DNA repair

Werner syndrome (WS) predisposes patients to cancer and premature aging, owing to mutations in WRN. The WRN protein is a RECQ-like helicase and is thought to participate in DNA double-strand break (DSB) repair by non-homologous end joining (NHEJ) or homologous recombination (HR). It has been previously shown that non-homologous DNA ends develop extensive deletions during repair in WS cells, and that this WS phenotype was complemented by wild-type (wt) WRN. WRN possesses both 3' --> 5' exonuclease and 3' --> 5' helicase activities. To determine the relative contributions of each of these distinct enzymatic activities to DSB repair, we examined NHEJ and HR in WS cells (WRN-/-) complemented with either wtWRN, exonuclease-defective WRN (E-), helicase-defective WRN (H-) or exonuclease/helicase-defective WRN (E-H-). The single E-and H- mutants each partially complemented the NHEJ abnormality of WRN-/- cells. Strikingly, the E-H- double mutant complemented the WS deficiency nearly as efficiently as did wtWRN. Similarly, the double mutant complemented the moderate HR deficiency of WS cells nearly as well as did wtWRN, whereas the E- and H- single mutants increased HR to levels higher than those restored by either E-H- or wtWRN. These results suggest that balanced exonuclease and helicase activities of WRN are required for optimal HR. Moreover, WRN appears to play a structural role, independent of its enzymatic activities, in optimizing HR and efficient NHEJ repair. Another human RECQ helicase, BLM, suppressed HR but had little or no effect on NHEJ, suggesting that mammalian RECQ helicases have distinct functions that can finely regulate recombination events.

A review of the state of research into the role of iron in stroke

Iron is a double edged sword for living systems, as it is essential for a wide range of metabolic processes while it also has potential deletereous effects. Oxidative metabolism during ischaemic stroke together with high iron content in the brain synergise to increase the oxidative damage. High plasma ferritin, as a measurement of iron stores, and high cerebrospinal fluid ferritin have been related to poor outcome in stroke patients. Iron has been found in pooled gruels of atheromatous lesions and has been related to other diseases. Further epidemiological studies are required to determine the effect of iron on the development of cardiovascular diseases. Until the precise effect of iron overloading is established it is recommended that iron supplements should only be prescribed when there is a clear deficiency.

Randomised double-blind placebo-controlled trial of thrombolytic therapy with intravenous alteplase in acute ischaemic stroke (ECASS II). Second European-Australasian Acute Stroke Study Investigators

BACKGROUND

Thrombolysis for acute ischaemic stroke has been investigated in several clinical trials, with variable results. We have assessed the safety and efficacy of intravenous thrombolysis with alteplase (0.9 mg/kg bodyweight) within 6 h of stroke onset.

METHODS

This non-angiographic, randomised, double-blind, trial enrolled 800 patients in Europe, Australia, and New Zealand. Computed tomography was used to exclude patients with signs of major infarction. Alteplase (n=409) and placebo (n=391) were randomly assigned with stratification for time since symptom onset (0-3 h or 3-6 h). The primary endpoint was the modified Rankin scale (mRS) at 90 days, dichotomised for favourable (score 0-1) and unfavourable (score 2-6) outcome. Analyses were by intention to treat.

FINDINGS

165 (40.3%) alteplase-group patients and 143 (36.6%) placebo-group patients had favourable mRS outcomes (absolute difference 3.7%, p=0.277). In a posthoc analysis of mRS scores dichotomised for death or dependency, 222 (54.3%) alteplase-group and 180 (46.0%) placebo-group patients had favourable outcomes (score 0-2; absolute difference 8.3%, p=0.024). Treatment differences were similar whether patients were treated within 3 h or 3-6 h. 85 (10.6%) patients died, with no difference between treatment groups at day 90+/-14 days (43 alteplase, 42 placebo). Symptomatic intracranial haemorrhage occurred in 36 (8.8%) alteplase-group patients and 13 (3.4%) placebo-group patients.

INTERPRETATION

The results do not confirm a statistical benefit for alteplase. However, we believe the trend towards efficacy should be interpreted in the light of evidence from previous trials. Despite the increased risk of intracranial haemorrhage, thrombolysis with alteplase at a dose of 0.9 mg/kg in selected patients may lead to a clinically relevant improvement in outcome.

Value of immunologic testing in stroke patients. A prospective multicenter study

BACKGROUND AND PURPOSE

The aims of this prospective and multicenter study were to determine the frequency of anticardiolipin and antinuclear antibodies in an unselected ischemic and hemorrhagic stroke population and to evaluate the clinical significance of these autoantibodies.

METHODS

Over a 1-year period, we collected plasma from 481 consecutive patients with ischemic or hemorrhagic stroke attending four different hospitals. Blood (10 mL) was drawn from each subject into a citrated glass tube. Plasma was obtained immediately by centrifugation and was stored at -70 degrees C until use. Concentrations of IgM and IgG anticardiolipin antibodies were measured at room temperature in normal (not heat-treated) plasma by standardized enzyme-linked immunosorbent assay. All sera were treated by indirect immunofluorescence on mouse liver and kidney sections for antinuclear antibodies.

RESULTS

A total of 481 patients (325 men, 156 women) 16 to 90 years in age (mean age, 61 years) were studied. Anticardiolipin antibodies were present in 5 of 481 (1.04%) patients. One patient was IgG positive and four patients were IgM positive. Of 481 patients, 35 (7.2%) were positive for antinuclear antibodies. Anti-DNA antibodies were not demonstrable in any patient.

CONCLUSIONS

The frequency of anticardiolipin antibodies in a heterogeneous stroke population is possibly lower than reported. The routine screening of anticardiolipin and antinuclear antibodies in a stroke population is of questionable value.

Computed tomography in acute alcoholic myopathy

We describe a case of acute alcoholic myopathy evaluated by computed tomography. Computed tomography showed a low-density, delimited area in the semimembranous muscle and edema of the subcutaneous cell tissue, permitting determination of the extent of the disease and its localization for purposes of biopsy and fasciotomy of the affected muscle.