Open multi-culture platform for simple and flexible study of multi-cell type interactions

The study of multi-cell-type (MCT) interactions has the potential to significantly impact our understanding of tissue and disease biology. Such studies require innovative culture tools for unraveling the contributions of each cell type. Micro- and macro-scale platforms for MCT culture each have different advantages and disadvantages owing to their widely different capabilities, availability, and ease-of-use. However, as evidenced in the literature, there are very few examples of MCT studies and culture platforms, suggesting both biological and technical barriers. We have developed an open multi-culture platform to promote more rapid progress by integrating advantages of both micro- and macro-scale culture devices. The proposed open multi-culture platform addresses technical barriers by allowing easy customization, independent control of basic physical culture parameters, and incorporation of multiple culture modalities (e.g., 2D, 3D, transwell, and spheroid). The design also permits the user to obtain independent endpoints for each culture region. We demonstrate use of the platform in two example studies where we evaluated how cell ratio and cell types influence the response of triple negative breast cancer cells to heat damage and Hedgehog signaling. We also show that the platform can improve soluble factor transport between cell types compared to compartmentalized macro- and micro-scale alternatives. Last, we examine current and future challenges of the platform. We envision simple, yet flexible and customizable, platforms such as this will be important for advancing in vitro study of tissue and tumor biology.

Abstract 174: Collagen fiber orientation influences tumor cell growth and Hedgehog signaling in the breast tumor microenvironment

Collagen matrix architecture is an important player in tumor transition to therapeutic resistance. Several studies have shown that high level of fiber orientation and density of collagen type I matrix enhances tumor cell invasion, decrease drug response and influence tumor metabolism, but the mechanisms of action that support transition to therapeutic resistance are not fully understood. We developed a 3D culture platform to evaluate the effects of collagen matrix architecture in the sensitivity of tumor and stromal cells to tumor promoting ligands and pharmacological inhibitors. Estrogen (E2) and Hedgehog (Hh) signaling pathways were selected for evaluation due to their relevance in breast cancer prognosis and tumor progression. In this 3D culture platform, electrospun collagen fiber sheets of random or aligned orientation are bound to double-sided medical grade tape to generate collagen fiber stickers. Automated cutting plotter allows razor-printing for precisely cutting shapes from collagen fiber sticker sheets. Round shapes were applied like a sticker to the bottom of culture well plates prior to cell seeding. The percentage of matrix porosity fiber orientation and diameter was quantified by Scanning Electron Microscopy (SEM) and Image J analysis. For estrogen signaling studies, MCF-7 cells were seeded in collagen fibers of random or aligned orientation using hormone free-culture conditions. Cells were treated +/- E2 (10nM) ligand and +/- estrogen receptor signaling inhibitors (Fulvestrant and Tamoxifen). Tumor cell proliferation was quantified at 48hrs via Image Cytometry. For Hh signaling studies, expression levels of GLI1, PTCH1 and SMO Hh target genes were monitored in triple negative breast cancer (MDA-MB-231 and MDA-MB-468) and mesenchymal cells. Cells were seeded on collagen fibers and treated with sonic hedgehog ligand for 24hrs. Tumor and mesenchymal cells were harvest for viability and qRT-PCR analysis respectively. Evaluation of cell growth in MCF-7 cultures shows that a fibrillar structure of collagen matrix in combination with high degree of fiber orientation can significantly increase cell proliferation as compared to gelatin or tissue culture plastic substrates. Collagen fibers significantly supported hormone-independent tumor growth at similar levels to those observed in E2 treatment. Increased proliferation levels were maintained in ER inhibition groups particularly when cultured in aligned collagen fibers. In Hh signaling studies, overexpression of GLI1 and SMO genes were observed for collagen fibers matrixes as compared to gelatin and tissue culture plastic. Overall our results show for the first time that collagen fiber architecture can promote hormone-independent growth dependence in breast cancer cells and activation of hedgehog signaling in tumor and mesenchymal cells.

Citation Format: Ana M. Reyes, Jorge Almodovar, Maribella Domenech. Collagen fiber orientation influences tumor cell growth and Hedgehog signaling in the breast tumor microenvironment [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 174.

Razor-printed sticker microdevices for cell-based applications

Tape-based razor-printing is a flexible and affordable ultra-rapid prototyping approach for microscale device fabrication. However, integration of this prototyping approach into cell-based assay development has been limited to proof of principle demonstrations. This is in large part due to lack of an established or well-characterized option for biocompatible adhesive tape. Without such an option, integration of these areas will remain unexplored. Therefore, to address this critical hurdle, we characterized microscale devices made using a potentially biocompatible double-sided adhesive, ARCare 90106. We validated tape-based device performance against 96-well plates and PDMS microdevices with respect to cell viability, hydrophobic small molecule sequestration, the potential for leaching compounds, use in fluorescence microscopy, and outgassing (bubble formation). Results supported the tape as a promising tool for future cell-based assay development. Therefore, we subsequently demonstrated specific strengths enabled by the ultra-rapid (<1 h per prototype) and affordable (∼$1200 cutting plotter, <$0.05 per prototype) approach. Specifically, data demonstrate the ability to integrate disparate materials for advanced sticker-device functionality such as bonding of polystyrene devices to glass substrates for microscopy applications, inclusion of membranes, and incorporation of different electrospun biomaterials into a single device. Likewise, the approach allowed rapid adoption by uninitiated users. Overall, this study provides a necessary and unique contribution to the largely separate fields of tape-based razor-printing and cell-based microscale assay development by addressing a critical barrier to widespread integration and adoption while also demonstrating the potential for new and future applications.

Hedgehog-mesenchyme gene signature identifies bi-modal prognosis in luminal and basal breast cancer sub-types

Hedgehog signaling (Hh) has been shown to be hyper-activated in several cancers. However, active Hh signaling can promote or inhibit tumor growth; thus identification of markers beyond main canonical Hh target genes is needed to improve patient selection and clinical outcome in response to Hh inhibitors. Cancer-associated fibroblasts (CAFs) have been linked with tumor progression and beneficial response to Hh inhibitors. Thus, we hypothesized that genes associated with Hh-activated CAFs can be used for stratification of tumors that will benefit from Hh inhibitors. In this work, we evaluated a 15-gene fingerprint that combines Hh and mesenchymal genes associated with CAF phenotype to profile breast cancer sub-types based on gene expression patterns among clustered groups. About 3800 cancer samples were evaluated using random forest models and linear discriminant analysis to sort breast cancer by subtypes and therapeutic approach. The results showed that the Hh-mesenchyme gene fingerprint has a highly sensitive and differential expression pattern among basal and luminal A sub-groups. Basal samples with high levels of Hh target genes had better prognosis than luminal A samples. Luminal A samples with a tendency towards Hh signaling suppression had higher overall and disease-free survival rates particularly if deprived of hormone therapy. Hh transcriptional repressor GLI3 and signaling activator SMO were the top 2 genes for discriminating among samples with active Hh signaling in human breast cancer subtypes and Hh-inhibitor resistant tumors. Caveolin-1 (CAV1), a gene with low expression in CAFs, shows strong correlation with active Hh signaling and discrimination among survival curves in luminal A patients with active or inactive Hh signaling. Our data suggest that CAV1 is an important gene for monitoring Hh inhibition in tumors and support further stratification by hormone therapy status prior to use of Hh inhibitors.

HIF pathway and c-Myc as biomarkers for response to sunitinib in metastatic clear-cell renal cell carcinoma

BACKGROUND

Clear-cell renal cell carcinoma (ccRCC) is a heterogeneous disease with a different clinical behavior and response to targeted therapies. Differences in hypoxia-inducible factor (HIF) expression have been used to classify von Hippel-Lindau gene (VHL)-deficient ccRCC tumors. c-Myc may be driving proliferation in HIF-2α-expressing tumors in a growth factor-independent manner.

OBJECTIVE

To explore the HIF-1α, HIF-2α and c-Myc baseline expression as potential predictors of sunitinib outcome as well as the effectiveness and safety with sunitinib in patients with metastatic ccRCC in routine clinical practice.

METHODS

This was an observational and prospective study involving 10 Spanish hospitals. Formalin-fixed, paraffin-embedded primary tumor samples from metastatic ccRCC patients who received sunitinib as first-line treatment were analyzed. Association between biomarker expression and sunitinib treatment outcomes was evaluated. Kaplan-Meier method was applied to measure progression-free survival (PFS) and overall survival.

RESULTS

Eighty-one patients were included: median PFS was 10.8 months (95% CI: 7.4-13.5 months), median overall survival was 21.8 months (95% CI: 14.7-29.8 months) and objective response rate was 40.7%, with 7.4% of patients achieving a complete response. Molecular marker staining was performed in the 69 available tumor samples. Significant association with lower PFS was identified for double c-Myc/HIF-2α-positive staining tumors (median 4.3 vs 11.5 months, hazard ratio =2.64, 95% CI: 1.03-6.80, P=0.036). A trend toward a lower PFS was found in positive c-Myc tumors (median 5.9 vs 10.9 months, P=0.263). HIF-1α and HIF-2α expression levels were not associated with clinical outcome.

CONCLUSION

These preliminary results suggest that predictive subgroups might be defined based on biomarkers such as c-Myc/HIF-2α. Further validation with more patients will be needed in order to confirm it. Outcomes with sunitinib in metastatic ccRCC in daily clinical practice resemble those obtained in clinical trials.

Abstract 1334: Mesenchymal cell sub-populations selectively modulate paracrine hedgehog signaling in triple negative breast cancer

Recent studies correlate Hedgehog (Hh) signaling with reduced survival rates in triple negative breast cancer (TNBC) patients. Activation of hedgehog signaling in the adjacent mesenchyme has been shown to promote tumor growth and it is a poor prognosis factor for TNBC. We developed a novel tumor-mesenchymal in vitro model of hedgehog signaling in TNBC to evaluate the role of mesenchymal cell sub-populations in the proliferative potential and stem cell markers of breast cancer cells using a custom designed multiwell array. As a source of mesenchymal cell sub-populations we evaluated myofibroblasts, mesenchymal stem cells derived from bone marrow or adipose tissue and tumor cells that undergo epithelial-mesenchymal transition (EMT). Tumor cells were culture with 1 or 2 mesenchymal cell sub-populations in adjacent compartments +/- SHH ligand for 72-96hrs. Active Hh signaling was confirmed by up-regulation of main Hh target genes (e.g. Gli1, Patch1). Paracrine Hh signaling only in bone marrow-derived mesenchymal stem cell and EMT significantly increased proliferation (10-15%) of TNBC and normal breast cancer cell lines. Addition of adipose-derived mesenchymal stem cells or pharmacological Hh inhibitors (Cyclopamine and Gant61) partially abolished tumor growth indicating that other non-canonical signals are involve in paracrine Hh-driven tumors. Cancer stem cell markers were selectively modulated in co-cultures. Our results suggest that paracrine Hh signaling-driven by bone marrow and EMT mesenchymal are potential therapeutic targets to treating TNBC.

Citation Format: Karla P. Ramos, Maribella Domenech. Mesenchymal cell sub-populations selectively modulate paracrine hedgehog signaling in triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1334. doi:10.1158/1538-7445.AM2017-1334

Abstract P4-21-32: Treatment of early HER2-positive breast cancer in trastuzumab era in everyday clinical practice: An overview after 10 years of its approval

Introduction: The addition of Trastuzumab(T) to chemotherapy (CT) revolutionized HER2-positive breast cancer(BC) and changed its natural history. We reviewed the efficacy of T outside clinical trials in a cancer comprehensive center.

Methods: Ambiespective and descriptive study was conducted in Catalan Institute of Oncology (ICO-Barcelona). Estimates of progression-free survival (PFS) and overall survival (OS) were obtained with the Kaplan-Meier method and compared with LogRank test. The association of clinic-pathological variables and outcome was studied by χ2and Cox proportional hazard analysis.

Results: 430 consecutive early HER2-positive BC patients (pts) were treated with adjuvant/neoadjuvant T and CT from Jan 2005 to Dec 2012. Pt basal characteristics are reported in Table 1. Neoadjuvant treatment was administrated in 230pts (54%) and in 200 (46%) in adjuvancy. Pathological complete response (pCR) in breast and nodes (ypT0/isypN0) was achieved in 48% of pts, with higher rates in hormone receptor (HR)-negative pts (62 vs 37% p=0.0005). Median duration of T: 10.6 months (m). 28%pts treated with neoadjuvant T+CT who achieved a pCR did not receive adjuvant T. Treatment discontinuation: 38pts (8.8%): 27pts due to cardiac toxicity and 4 relapsed during adjuvant T. In 87%pts, neoadjuvant CT was based on anthracyclines(A) and taxanes. Adjuvant CT: A and taxanes in 57.4%; 14%pts FAC, 15.4% A-CMF and 12% TCH. At a median follow-up of 70m (3-135), 44pts (10.4%) had relapsed: 33pts with distant M1, 9pts with only loco-regional disease and 2pts contralateral HER2-positive BC. M1 location: 46% visceral, 34% bone/lymph nodes and 20% in central nervous system (CNS). PFS was 23.4m(0-88); median OS was not reached; estimated 10 years-OS was 86.5%. Pts treated with A and taxanes had a significantly better OS compared to those treated with other CT (113 vs 98m, p= 0.009). Kaplan-Meier curve showed numerically higher relapses at 10 years in HR-positive pts (83 vs 90% p=0.8). Pts with pCR had significantly better OS (113 vs 104m, p=0.006). Pts with CNS-metastases had a significantly worse OS (13 vs 26m,p=0,02) and those with HR-negative (49 vs 24m, p= 0.033).

Conclusion: In everyday clinical practice, recurrences after adjuvant/neoadjuvant trastuzumab in HER2-positive BC were less than described in the T-pivotals trials, with 10% of recurrences at a median of FU of 70m. In our series, estimated 10 years-OS was 86.5%. Pts treated with A and taxanes had a significantly better OS as well as those pts who achieved a pCR. On the contrary, pts with CNS M1 and those with HR-negative had worse prognosis.

Table 1Median age51.9y (27-83)Stage I/II/III106 (25%)/ 226 (52%)/ 97 (23%)HR Positive/ Negative249 (58%)/181 (42%)

Citation Format: Ortega A, Domenech M, Falo C, Gil M, Stradella A, Fernandez A, Morilla I, Villanueva R, Castany R, Vazquez S, Molina K, Bergamino M, Navarro V, Pernas S. Treatment of early HER2-positive breast cancer in trastuzumab era in everyday clinical practice: An overview after 10 years of its approval [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-21-32.

Abstract B02: Open multi-microwell array for the study of paracrine signaling in tumors

The development and progression of tumors are modulated by the interaction among multiple cell types present at the tumor adjacent tissue. Few in vitro cell culture platforms allow one to test multi-cellular interactions and those suitable require high numbers of cells limiting studies to cell lines and excluding heterogeneous patient samples, and fail to provide tunable discrete adjacent compartments for the retrieval of independent cell population readouts. Mixing of cells in adjacent compartments and cell sorting after mixed culture represent a costly and time consuming procedure that often results is lost, reduction and/or damage of the recovered sample. To overcome some of these limitations we have developed an open multi-microwell array that enables co-culture of up to 4 cell populations in discrete adjacent wells using either 2- or 3-dimension culture conditions. The circular microwells are made of poly-dimethyl siloxane (PDMS) and placed on top of glass or tissue culture plastic. The open-well format allows cells and culture media to be manually loaded and replaced using a pipette independently of passive pumping method, and without the need of vacuum-assisted filling or syringe pumps. The microwell array is aligned to a 96well plate format for automated fluorescent readouts. The cell culture surface area of each microwell is 5.7mm2 (5ul) and can accommodate 5,000-10,000 cells but the design of each microwell can be scale-down to accommodate smaller cell samples. The adjacent microwells are contained within an outer-ring of 8mm diameter and 750um height. After cell seeding, adjacent compartments can be connected by dispensing a volume of 30-40ul inside the outer ring. A model of tumor-mesenchyme paracrine Hedgehog signaling was developed and characterized to show the feasibility of this array for multi-cell soluble factor signaling studies. Activation of Hedgehog (Hh) signaling in the mesenchyme promotes proliferation of tumor cells via secreted factors. As a source of mesenchymal cell sub-types we evaluated TGF-b treated fibroblasts and tumor epithelial cells that undergo epithelial-mesenchymal transition. Myofibroblast phenotype was confirmed based on overexpression of smooth muscle actin, vimentin and fibroblast activating protein, and reduce levels of caveolin-1. Active Hh signaling and pharmacological inhibition with cyclopamine were confirmed by up- and down- regulation of canonical Hh target genes Gli1 and Patch1. Active hedgehog signaling and cell viability was maintained over 5-7days 2-dimensional and collagen type I embedded mesenchymal cells. Breast-derived human epithelial and mesenchymal cells co-cultured in microwells and transwells showed similar increase in tumor cell proliferation rates but with a reduction of 80% or more in the total cells needed compared to transwells. Flow cytometer read-outs of proliferation and tumor cell distribution of CD44/CD24 cell surface receptors were similar among transwells and microwells. Adjacent culture of mouse derived fibroblasts (NIH-3T3) and human tumor cells showed recovery of genomic sample without cell-population mixing using primers for specific for human and mouse GAPDH. Doubling of the number of microwells with mesenchymal cells modulated the observed proliferative effect in tumor cells suggesting that mesenchymal cell ratios modulate tumor response to paracrine Hh signaling. This observation could not be replicated in macro-scale platforms as active Hh signaling in the mesenchyme is achieved via cell growth arrest using a combination of low serum and cell confluence. The open multi-microwell array represents a new user-friendly multi-culture microscale array with optimized capabilities for the study of paracrine signaling among discrete cell populations compared to macroscale culture technology.

Citation Format: Karla P. Ramos, Fernando Boria, Maribella Domenech. Open multi-microwell array for the study of paracrine signaling in tumors. [abstract]. In: Proceedings of the AACR Special Conference on Engineering and Physical Sciences in Oncology; 2016 Jun 25-28; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2017;77(2 Suppl):Abstract nr B02.

Tissue Engineering Strategies for Myocardial Regeneration: Acellular Versus Cellular Scaffolds?

Heart disease remains one of the leading causes of death in industrialized nations with myocardial infarction (MI) contributing to at least one fifth of the reported deaths. The hypoxic environment eventually leads to cellular death and scar tissue formation. The scar tissue that forms is not mechanically functional and often leads to myocardial remodeling and eventual heart failure. Tissue engineering and regenerative medicine principles provide an alternative approach to restoring myocardial function by designing constructs that will restore the mechanical function of the heart. In this review, we will describe the cellular events that take place after an MI and describe current treatments. We will also describe how biomaterials, alone or in combination with a cellular component, have been used to engineer suitable myocardium replacement constructs and how new advanced culture systems will be required to achieve clinical success.

Abstract B05: Mesenchymal-driven hedgehog signaling drives tumor cell growth and is a potential new target for triple-negative breast cancer

Triple negative breast cancer (TNBC) is a clinical therapeutic challenge due to the lack of receptors for estrogen, progesterone, and human epidermal growth factor receptor 2 which limits treatment options to chemotherapy and radiation. With current standard therapy less than 30% will survive the 5-year remission rate, especially Hispanic and African-American women where TNBC is more frequent and has the lowest (&lt;14%) 5-year survival rates. Recent studies indicate that Hedgehog (Hh) signaling is active and correlates with reduced survival rates in TNBC patients. However, the role of the Hh signaling in the breast tumor microenvironment is not well understood. A main cellular mediator of Hh signaling is the adjacent mesenchyme which promotes tumor growth via a paracrine interaction, but which is also highly heterogeneous. As mesenchymal sub-types have been associated to specific pharmacological therapies, understanding of the mechanisms in mesenchymal-driven tumors is necessary for combinatorial pharmacological treatments that can increase survival rates and eliminate tumor relapse in patients. We developed a tumor-mesenchymal in vitro model to evaluate the role of mesenchymal cell sub-types from different sources in the proliferative potential and stem cell markers of breast cancer cells using a custom designed multiwell array. Cells were culture in adjacent compartments and active Hh signaling was confirmed by up-regulation of canonical Hh target genes Gli1, Patch1 and SMO. As a source of mesenchymal cell sub-types we evaluated TGF-β treated fibroblasts, cancer- associated and normal breast primary fibroblasts, and tumor epithelial cells that undergo epithelial-mesenchymal transition (EMT). Paracrine Hh signaling significantly increased proliferation (5-10%) of tumor cells after 72-96hrs in co-culture. Cells that undergo EMT promoted cell growth at higher rates than myofibroblasts. SHH treatment alone (without TGF-β pre-treatment) had an inhibitory effect in the proliferation rates of the adjacent epithelium compartment. Observed increase in tumor cell proliferation was abolished when treated with the Hh signaling inhibitor cyclopamine. Stem cell surface markers CD44+CD24- remained unchanged but a significant increase was observed in the proliferating CD44+/CD24+ sub-population. Similar results were observed in normal human breast cells suggesting that activation of Hh signaling in the mesenchyme is sufficient to promote cell growth in the epithelium. Computational analysis of a panel of genes associated to Hh signaling in breast cancer patients (&gt;500 samples) show a strong correlation among TNBC patients and mesenchymal-driven Hh signaling in &gt;80% of samples. We evaluated the distribution of mesenchymal cell-sub-types and stem cells among the sub-set of basal TNBC samples (82 samples). Gene markers associated to myofibroblasts, EMT, mesenchymal stem cell and cancer stem cell were found in samples with active Hh signaling and co-expressed in groups of two or more which represented the 45.6% of the total samples. The most abundant cell sub-type were cancer stem cells with 43% of the total samples and alone by itself in 13.9% of samples. Together, these results indicate that the Hh-pathway and adjacent tumor microenvironment are key players in the progression of TNBC. Mesenchymal cell component can modulate tumor growth behavior induced by Hh signaling and is a potential new clinical target for TNBC.

Citation Format: Maribella Domenech, Karla P. Ramos, Wandaliz Torres, Fernando Boria. Mesenchymal-driven hedgehog signaling drives tumor cell growth and is a potential new target for triple-negative breast cancer. [abstract]. In: Proceedings of the AACR Special Conference: Developmental Biology and Cancer; Nov 30-Dec 3, 2015; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(4_Suppl):Abstract nr B05.

Phosphodiesterase 4D inhibitors limit prostate cancer growth potential

Phosphodiesterase 4D (PDE4D) has recently been implicated as a proliferation-promoting factor in prostate cancer and is overexpressed in human prostate carcinoma. However, the effects of PDE4D inhibition using pharmacologic inhibitors have not been examined in prostate cancer. These studies examined the effects of selective PDE4D inhibitors, NVP-ABE171 and cilomilast, as anti-prostate cancer therapies in both in vitro and in vivo models. The effects of PDE4D inhibitors on pathways that are critical in prostate cancer and/or downstream of cyclic AMP (cAMP) were examined. Both NVP-ABE171 and cilomilast decreased cell growth. In vitro, PDE4D inhibitors lead to decreased signaling of the sonic hedgehog (SHH), androgen receptor (AR), and MAPK pathways, but growth inhibition was best correlated to the SHH pathway. PDE4D inhibition also reduced proliferation of epithelial cells induced by paracrine signaling from cocultured stromal cells that had activated hedgehog signaling. In addition, PDE4D inhibitors decreased the weight of the prostate in wild-type mice. Prostate cancer xenografts grown in nude mice that were treated with cilomilast or NVP-ABE171 had decreased wet weight and increased apoptosis compared with vehicle-treated controls. These studies suggest the pharmacologic inhibition of PDE4D using small-molecule inhibitors is an effective option for prostate cancer therapy.

IMPLICATIONS

PDE4D inhibitors decrease the growth of prostate cancer cells in vivo and in vitro, and PDE4D inhibition has therapeutic potential in prostate cancer.