In vitro vascularized tumor platform for modeling tumor-vasculature interactions of inflammatory breast cancer

Inflammatory breast cancer (IBC), a rare form of breast cancer associated with increased angiogenesis and metastasis, is largely driven by tumor-stromal interactions with the vasculature and the extracellular matrix (ECM). However, there is currently a lack of understanding of the role these interactions play in initiation and progression of the disease. In this study, we developed the first three-dimensional, in vitro, vascularized, microfluidic IBC platform to quantify the spatial and temporal dynamics of tumor-vasculature and tumor-ECM interactions specific to IBC. Platforms consisting of collagen type 1 ECM with an endothelialized blood vessel were cultured with IBC cells, MDA-IBC3 (HER2+) or SUM149 (triple negative), and for comparison to non-IBC cells, MDA-MB-231 (triple negative). Acellular collagen platforms with endothelialized blood vessels served as controls. SUM149 and MDA-MB-231 platforms exhibited a significantly (p < .05) higher vessel permeability and decreased endothelial coverage of the vessel lumen compared to the control. Both IBC platforms, MDA-IBC3 and SUM149, expressed higher levels of vascular endothelial growth factor (p < .05) and increased collagen ECM porosity compared to non-IBCMDA-MB-231 (p < .05) and control (p < .01) platforms. Additionally, unique to the MDA-IBC3 platform, we observed progressive sprouting of the endothelium over time resulting in viable vessels with lumen. The newly sprouted vessels encircled clusters of MDA-IBC3 cells replicating a key feature of in vivo IBC. The IBC in vitro vascularized platforms introduced in this study model well-described in vivo and clinical IBC phenotypes and provide an adaptable, high throughput tool for systematically and quantitatively investigating tumor-stromal mechanisms and dynamics of tumor progression.

Genetic characterization of four Algerian cattle breeds using microsatellite markers

Cattle plays a very important role in agriculture and food security in Algeria. In the present study, the genetic diversity and structure of Algerian indigenous cattle populations were evaluated by microsatellite markers. A total of 138 individuals belonging to four cattle breed populations were characterized using 22 microsatellite markers. A total of 360 alleles was detected across studied all loci. Results obtained for the mean number of alleles (16.36), expected heterozygosity (0.84) and polymorphic information content (0.82) indicated that the total analyzed populations are characterized by noticeable genetic variability. It can be said that there is a low genetic differentiation in the cattle populations studied considering obtained mean F_ST value (0.039). It was revealed 97.10% of the total genetic variation can be explained by genetic differences among individuals while 2.90% among populations. The structure, factorial correspondence analysis results and dendrogram showed that cattle populations studied are clustered in three groups. The present study has revealed an important knowledge about the genetic diversity and the relationship between some native cattle breeds raised in Algeria. The results showed that the breeds studied have a high genetic diversity. Moreover, it can be said that microsatellite markers used can be successfully used to determine genetic diversity and population structure in Algerian cattle breeds.

Abstract P6-15-04: Modeling limited breastfeeding and diet on IBC like tumor progression

Introduction/Motivation: We previously reported IBC patients with limited breast-feeding history have a worse prognosis than those with greater breast feeding history. Further, we reported pregnancy related factors including multiple early pregnancies and not breast feeding as well as obesity are risk factors for triple negative and ER+ subtypes. Significant evidence suggests the microenvironment drives IBC symptoms and growth pattern. We sought to characterize the impact of purported risk factors on tumor growth, IBC-like skin symptoms and mammary gland microenvironment in animal models.

Methods: We commissioned breeding of nulliparous, multiparous (x 2) force weaned, and multiparous naturally weaned (labeled nursing) mice. Mice in each of the three groups were fed either a low fat (10 Kcal %) or high fat (60 Kcal %) diet for three weeks before tumor cell injections. SUM 149 GFP Luc were injected into the left ventral #4 mammary fat pad. Mice were sacrificed, scored for the IBC-like symptom of gross skin invasion or evident skin symptoms, and tissue from the contralateral mammary gland were sectioned and stained with H and E. Analysis was performed on the 31 animals that developed primary tumors and were scored for skin invasion at the time of resection. Of these 26 mice had contralateral gland tissue assessed by H and E. Phenotypes including duct dilation, degree of adipose tissue, duct density, inflammation and necrosis were scored manually, 1-3 scale. Quadratic mixed models with random intercept were fitted to compare tumor growth. Fisher’s exact test and T-tests were performed to compare variables.

Results: Tumor incidence and latency were not different by risk factor group. Tumor growth was faster in multiparous force weaned versus others, P &lt; 0.0001, but unchanged by diet, P = 0.187. Force weaned animals on a high fat diet had a trend for increased skin invasion compared to others (force weaned high fat diet vs. other 85% vs. 42%; P = 0.08) suggesting a synergy for this IBC-like symptom. Contralateral gland ductal density (less dense) and ductal dilation (not dilated) were normal histologic variables which correlated with skin invasion on the tumor side (P =0.006 and P = 0.011, respectively). Gland density but not dilated ducts trended to correlation with force weaning, P = 0.07, but not diet.

Discussion: In this effect size finding pilot study, combined risk factors were associated with a higher incidence of skin invasion of SUM149 xenografts. Changes in the microenvironment in the contralateral gland typical of involution were significantly associated with skin invasion, and gland density trends towards association with force weaning. These data provide provocative pilot results linking histologic effects in the microenvironment to tumor growth characteristics and support the hypothesis that involution induced by forced weaning may facilitate IBC-like tumor growth. These studies facilitate well-powered additional work to establish mechanism and automate normal tissue evaluation.

Citation Format: Wintana Balema, Richard Larson, Renae Van Whye, Rong Ye, Jing Ning, Omar Rahal, Shane Stecklein, Savitri Krishnamurthy, Randa El-Zein, Wendy Woodward. Modeling limited breastfeeding and diet on IBC like tumor progression [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 P6-15-04.

Abstract P6-06-02: An in vitro microfluidic tumor platform for modeling and investigating tumor stromal interactions in inflammatory breast cancer

Introduction: Inflammatory breast cancer (IBC) is an aggressive and rare disease with poor prognosis, accounting for 10% of breast cancer mortality [1]. A primary factor contributing to the bleak prognosis is the lack of IBC specific treatments. There are currently no IBC specific therapies due to a lack of IBC specific diagnostic and targeting markers. Efforts focused on identifying driver mutations and tumor targets have implicated tumor stroma including stromal cells such as macrophages in mediating IBC-like symptoms. This highlights the significance of understanding the interactions of tumor cells with the tumor stroma in greater detail and the knowledge would enable determination of targetable biology from these interactions which would facilitate development of IBC specific treatments and therapeutics. What is needed is a model to capture the complexity of IBC, identify critical spatial hetero-cellular interactions and target them successfully in a physiologically relevant and high-throughput manner.

Approach: To address this need, we developed a 3D IBC microfluidic platform, unique in its simultaneous integration of functional blood vessels, tumor cells, macrophages, and type I collagen whose density, stiffness, and porosity mimics cancerous breast stroma. The platform will be used to study the influence of macrophage-tumor-endothelial interactions on 2 key critical features of IBC: vascular sprouting and formation of IBC emboli surrounded by vascular sprouts.

Results: The 3D IBC microfluidic platform composed of MDA-IBC3 cells and a functional endothelial blood vessel demonstrated both vascular sprouting and emboli formation, key features of IBC tumors seen in IBC patient derived xenograft (PDX) models. Additionally, we observed vascular nesting of MDA-IBC3 emboli, recreating a characteristic IBC phenomenon observed in Mary-X PDX models. Incorporation of macrophages significantly increased the number of new vascular sprouts, sprouting rate and resulted in sprouts forming at earlier time points. Additionally, the presence of macrophages resulted in the formation of a significantly more porous collagen matrix (p&lt;0.05), increased endothelial vessel permeability (p&lt;0.05) and expression of proangiogenic factors, IL-8 and MMP9 (p&lt;0.05, p&lt;0.05) compared to platforms without macrophages. 3D platforms with macrophages also exhibited vascular nesting of MDA-IBC3 emboli but no significant differences in the number of nested emboli were detected. Finally, in 3D platforms with macrophages, we observed intravasation of MDA-IBC3 emboli which was absent in platforms without macrophages.

Conclusion: IBC is an aggressive and invasive breast cancer with a poor prognosis linked to tumor-stroma interactions. Current preclinical to study IBC consist primarily of PDX models where determining the influence of specific signaling pathways and microenvironmental stimuli on tumor progression is challenging. Here we present a novel 3D microfluidic IBC platform to study tumor stromal interactions in a controlled manner. The MDA-IBC3 breast tumor platform demonstrated both vascular sprouting and emboli formation, key features of IBC seen in PDX models and the presence of macrophages increased both angiogenic sprouting and remodeling of the collagen matrix. The stark differences in the tumor platform response associated with macrophage presence strengthens the hypothesis of tumor stroma as a key player driving the aggressive nature of IBC and reveals a potential target for IBC therapeutics.

[1] Fernandez, S.V., et al., Breast cancer research and treatment, 140(1): p. 23-33, 2013

Citation Format: Manasa Gadde, Caleb Phillips, Omar Rahal, Wendy Woodward, Marissa Rylander, Thomas Yankeelov. An in vitro microfluidic tumor platform for modeling and investigating tumor stromal interactions in inflammatory breast cancer [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 P6-06-02.

Abstract 2564: The anticancer molecule TPEN induces DNA damage in human colon cancer cells

The maintenance of optimal metal levels is an essential aspect of cell homoeostasis. However, in many types of cancer these metal levels especially iron, zinc and copper diverge from normal levels. We have recently shown that the zinc chelator TPEN increases the generation of reactive oxygen species (ROS) which selectively kills colon cancer cells. We have also provided evidence that the redox cycling of copper is responsible for TPEN anticancer effects. In this study, we aimed to further decipher the mechanism of TPEN-induced cell death in colon cancer cells through studying its effect on DNA damage. HCT116 p53+/+ human colon cancer cells were seeded were treated with 5μM TPEN at 50% confluence The inhibition of cell growth was measured by MTT, while ROS production was measured by the DCFH Assay using flow cytometry. siRNAs against DNApk and Chk2 was used to investigate the involvement of these DNA damage sensors in TPEN activity. DNA damage was assessed by the comet assay. Phosphorylation of ATM, ATR, Chk1, Chk2 and H2AX by TPEN were detected immunocytochemically by multiparameter cytometry. Expression levels of Chk1/2, ATR and DNApK were determined by western blotting. We show that cell death by TPEN is associated with significant DNA damage, an effect that was dependent on ROS generation and on the redox cycling of copper, as evidenced by reversal of DNA damage in the presence of antioxidants (NAC, CAT) or the copper chelator neocuproine (Neo). DNA damage was associated with increased expression of p-H2AX and a significant activation of ATM/ATR signaling molecules, specifically p-ATM, p-ATR and p-Chk1. Interestingly, silencing DNApk and Chk2 reversed DNA damage caused by TPEN, suggesting the involvement of DNApk and ATM/ATR pathways in TPEN-mediated effects. This study shows for the first time the involvement of DNApk and Chk2 in TPEN-induced DNA damage and confirms our previous findings that the redox cycling of copper is the main mechanism by which TPEN induces cell death in human colon cancer cells.

Citation Format: Hala Gali-Muhtasib, Omar Rahal, Maamoun Fatfat, Carla Hankache, Bassam Osman, Hala Khalife, Khaled Machaca. The anticancer molecule TPEN induces DNA damage in human colon cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2564. doi:10.1158/1538-7445.AM2015-2564

Copper chelation selectively kills colon cancer cells through redox cycling and generation of reactive oxygen species

BACKGROUND

Metals including iron, copper and zinc are essential for physiological processes yet can be toxic at high concentrations. However the role of these metals in the progression of cancer is not well defined. Here we study the anti-tumor activity of the metal chelator, TPEN, and define its mechanism of action.

METHODS

Multiple approaches were employed, including cell viability, cell cycle analysis, multiple measurements of apoptosis, and mitochondrial function. In addition we measured cellular metal contents and employed EPR to record redox cycling of TPEN-metal complexes. Mouse xenografts were also performed to test the efficacy of TPEN in vivo.

RESULTS

We show that metal chelation using TPEN (5μM) selectively induces cell death in HCT116 colon cancer cells without affecting the viability of non-cancerous colon or intestinal cells. Cell death was associated with increased levels of reactive oxygen species (ROS) and was inhibited by antioxidants and by prior chelation of copper. Interestingly, HCT116 cells accumulate copper to 7-folds higher levels than normal colon cells, and the TPEN-copper complex engages in redox cycling to generate hydroxyl radicals. Consistently, TPEN exhibits robust anti-tumor activity in vivo in colon cancer mouse xenografts.

CONCLUSION

Our data show that TPEN induces cell death by chelating copper to produce TPEN-copper complexes that engage in redox cycling to selectively eliminate colon cancer cells.

Bidirectional signaling of mammary epithelium and stroma: implications for breast cancer--preventive actions of dietary factors

The mammary gland is composed of two major cellular compartments: a highly dynamic epithelium that undergoes cycles of proliferation, differentiation and apoptosis in response to local and endocrine signals and the underlying stroma comprised of fibroblasts, endothelial cells and adipocytes, which collectively form the mammary fat pad. Breast cancer originates from subversions of normal growth regulatory pathways in mammary epithelial cells due to genetic mutations and epigenetic modifications in tumor suppressors, oncogenes and DNA repair genes. Diet is considered a highly modifiable determinant of breast cancer risk; thus, considerable efforts are focused on understanding how certain dietary factors may promote resistance of mammary epithelial cells to growth dysregulation. The recent indications that stromal cells contribute to the maintenance of the mammary epithelial 'niche' and the increasing appreciation for adipose tissue as an endocrine organ with a complex secretome have led to the novel paradigm that the mammary stromal compartment is itself a relevant target of bioactive dietary factors. In this review, we address the potential influence of dietary factors on mammary epithelial-stromal bidirectional signaling to provide mechanistic insights into how dietary factors may promote early mammary epithelial differentiation to decrease adult breast cancer risk.

In utero and lactational exposure to blueberry via maternal diet promotes mammary epithelial differentiation in prepubescent female rats

Early developmental events influence the fine tuning of later susceptibility to adult diseases. Diet is a determinant of breast cancer risk, and our previous studies showed that diet-mediated changes in transcriptional programs promote early mammary gland differentiation. Although consumption of fruits is considered to elicit multiple health benefits, little is known on whether associated bioactive components modify the early differentiation program in developing mammary glands. Here, we evaluated the hypothesis that early exposure (in utero and lactational) to blueberry through maternal diet enhances mammary epithelial differentiation in female offspring. Pregnant Sprague-Dawley rats beginning at gestation day 4 were fed American Institute of Nutrition-based diets containing casein and whole blueberry powders added to casein at 2.5%, 5.0%, and 10% weight/weight. Female pups at weaning were evaluated for growth and mammary tissue parameters. Blueberry at 5% dose increased body and adipose fat weights, relative to the other diets. Mammary branch density and terminal end bud size were highest for the 5% blueberry group, whereas terminal end bud numbers were not affected by all diets. Mammary ductal epithelial cells of the 5% blueberry group had lower nuclear phosphorylated histone 3 and higher nuclear tumor suppressor phosphatase and tensin homolog deleted in chromosome 10 (PTEN) levels than the casein group. Although sera of both diet groups had similar antioxidant capacity, 5% blueberry sera elicited higher nuclear PTEN accumulation in human MCF-10A mammary epithelial cells. Our studies identify developing mammary glands as early targets of blueberry-associated bioactive components, possibly through systemic effects on epithelial PTEN signaling.

The emerging role of Krüppel-like factors in endocrine-responsive cancers of female reproductive tissues

Krüppel-like factors (KLFs), of which there are currently 17 known protein members, belong to the specificity protein (Sp) family of transcription factors and are characterized by the presence of Cys(2)/His(2) zinc finger motifs in their carboxy-terminal domains that confer preferential binding to GC/GT-rich sequences in gene promoter and enhancer regions. While previously regarded to simply function as silencers of Sp1 transactivity, many KLFs are now shown to be relevant to human cancers by their newly identified abilities to mediate crosstalk with signaling pathways involved in the control of cell proliferation, apoptosis, migration, and differentiation. Several KLFs act as tumor suppressors and/or oncogenes under distinct cellular contexts, underscoring their prognostic potential for cancer survival and outcome. Recent studies suggest that a number of KLFs can influence steroid hormone signaling through transcriptional networks involving steroid hormone receptors and members of the nuclear receptor family of transcription factors. Since inappropriate sensitivity or resistance to steroid hormone actions underlies endocrine-related malignancies, we consider the intriguing possibility that dysregulation of expression and/or activity of KLF members is linked to the pathogenesis of endometrial and breast cancers. In this review, we focus on recently described mechanisms of actions of several KLFs (KLF4, KLF5, KLF6, and KLF9) in cancers of the mammary gland and uterus. We suggest that understanding the mode of actions of KLFs and their functional networks may lead to the development of novel therapeutics to improve current prospects for cancer prevention and cure.

Induction of PTEN-p53 Crosstalk in Mammary Epithelial Cells: A Novel Mechanism of Breast Cancer Prevention by the Dietary Factor Genistein

Consumption of soy foods either at an early age or for lifetime has been associated with reduced risk for developing breast cancer in humans and in animal models. However, this association continues to be controversial and the precise mechanisms for protection remain elusive. Among the soy products, the isoflavone genistein (GEN) has been widely suggested to confer mammary tumor protection. Previously we demonstrated the increased expression of tumor suppressors PTEN and p53 in mammary epithelial cells (MECs) isolated from young adult female rats fed dietary soy protein isolate (SPI) or casein (CAS) supplemented with GEN, when compared to MECs from rats fed the control (CAS) diet. Since NMU-administered rats fed SPI had reduced tumor incidence and increased tumor latency than those fed CAS, PTEN and p53 likely mediate the observed tumor resistance with SPI in vivo. We hypothesized that GEN induction of PTEN and p53 in MECs results in the formation of a PTEN/p53 functional complex to negatively regulate breast cancer development. Here, we used the human non-tumorigenic, ER-negative mammary epithelial cell line, MCF-10A, as an in vitro system to mechanistically dissect ER-independent actions of GEN involving PTEN and p53. GEN (40 nM, 2μM) augmented PTEN and p53 expression in treated relative to control cells. GEN also induced nuclear co-localization and physical association of PTEN and p53. To test a functional consequence of GEN-induced PTEN/p53 cross-talk on mammary epithelial phenotype, we analyzed GEN effects on cell cycle progression and acini formation in 3D cultures. Our results showed attenuated cell proliferation and lower cyclin D1 and pleiotrophin transcript levels in GEN-treated cells, which were abrogated by small interfering RNA to PTEN, indicating PTEN-dependence. Using FACS analysis, we showed that GEN induced cell cycle arrest at G0-G1 phase. Treatment with GEN promoted early acini formation of MECs grown in Matrigel, which temporally coincided with PTEN-dependent suppression of p21 and p27 transcript levels. Further analyses of GEN effects on MECs demonstrated induction by GEN of PTEN promoter-luc reporter activity as measured by dual-luciferase assay. Interestingly, treatment with siRNA to either PTEN or p53 reduced basal and GEN-induced PTEN promoter activity. Given that p53 binds to the PTEN promoter, our results suggest a feed-forward cycle in which dietary factor (GEN) induction of nuclear PTEN leads to PTEN promotion of its own signaling. By maintaining a stable pool of nuclear p53 to boost its transcription, PTEN ensures its continuous expression in MECs to favor cell differentiation. These data elucidate a novel mechanism by which dietary factors with PTEN-inducing activity may attenuate breast cancer risk and development. Funding by USDA-CRIS 6251-5100002-06S and the Department of Defense Breast Cancer Program (0810548).

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3149.

Ultra violet-induced localized inflammatory hyperalgesia in awake rats and the role of sensory and sympathetic innervation of the skin

Exposure to mid range ultrat violet radiations (UVBs) has been shown to produce systemic inflammation and hyperalgesia in mice [Saadé, N.E., Nasr, I.W., Massaad, C.A., Safieh-Garabedian, B., Jabbur, S.J., Kanaan, S.A., 2000. Modulation of ultraviolet-induced hyperalgesia and cytokine upregulation by interleukins 10 and 13. Br. J. Pharmacol. 131, 1317-1324]. Our aim was to characterize a new rat model of localized exposure to UVB and to determine the role of skin innervation in the observed hyperalgesia and cytokine upregulation. In several groups of rats one hindpaw was exposed to UVB (250-350 mJ/cm(2)) and this was followed by the application, to the plantar area of the paw, of either Von Frey hairs or a few acetone drops to measure tactile and cold allodynia, respectively. Thermal hyperalgesia was assessed by the paw withdrawal latency and duration. Cytokine levels were determined, by ELISA, in processed samples of skin tissue isolated from the exposed and non-exposed paws. UVB induced a biphasic thermal hyperalgesia and cold and tactile allodynia with an early phase that peaked at 3-6h and disappeared at 24h and a late phase with a peak at 48 h and recovery at 72-h post-exposure. Tumor necrosis factor, interleukins 1 beta, 6, 8, 10 and NGF levels were significantly increased following the same biphasic temporal pattern. Chemical ablation of capsaicin sensitive afferents and guanethidine injection produced significant alteration of the hyperalgesia and allodynia. The increase in cytokine levels by UVB was also altered by both treatments. The present study describes a new animal model for localized UVB-induced inflammatory hyperalgesia and provides evidence about the involvement of neurogenic mechanisms in the observed hyperalgesia and upregulation of proinflammatory mediators.