JAK-STAT Signaling in Inflammatory Breast Cancer Enables Chemotherapy-Resistant Cell States

Inflammatory breast cancer (IBC) is a difficult-to-treat disease with poor clinical outcomes due to high risk of metastasis and resistance to treatment. In breast cancer, CD44+CD24- cells possess stem cell-like features and contribute to disease progression, and we previously described a CD44+CD24-pSTAT3+ breast cancer cell subpopulation that is dependent on JAK2/STAT3 signaling. Here we report that CD44+CD24- cells are the most frequent cell type in IBC and are commonly pSTAT3+. Combination of JAK2/STAT3 inhibition with paclitaxel decreased IBC xenograft growth more than either agent alone. IBC cell lines resistant to paclitaxel and doxorubicin were developed and characterized to mimic therapeutic resistance in patients. Multi-omic profiling of parental and resistant cells revealed enrichment of genes associated with lineage identity and inflammation in chemotherapy-resistant derivatives. Integrated pSTAT3 chromatin immunoprecipitation sequencing and RNA sequencing (RNA-seq) analyses showed pSTAT3 regulates genes related to inflammation and epithelial-to-mesenchymal transition (EMT) in resistant cells, as well as PDE4A, a cAMP-specific phosphodiesterase. Metabolomic characterization identified elevated cAMP signaling and CREB as a candidate therapeutic target in IBC. Investigation of cellular dynamics and heterogeneity at the single cell level during chemotherapy and acquired resistance by CyTOF and single cell RNA-seq identified mechanisms of resistance including a shift from luminal to basal/mesenchymal cell states through selection for rare preexisting subpopulations or an acquired change. Finally, combination treatment with paclitaxel and JAK2/STAT3 inhibition prevented the emergence of the mesenchymal chemo-resistant subpopulation. These results provide mechanistic rational for combination of chemotherapy with inhibition of JAK2/STAT3 signaling as a more effective therapeutic strategy in IBC.

SIGNIFICANCE

Chemotherapy resistance in inflammatory breast cancer is driven by the JAK2/STAT3 pathway, in part via cAMP/PKA signaling and a cell state switch, which can be overcome using paclitaxel combined with JAK2 inhibitors.

Intratumor heterogeneity defines treatment-resistant HER2+ breast tumors

Targeted therapy for patients with HER2-positive (HER2+) breast cancer has improved overall survival, but many patients still suffer relapse and death from the disease. Intratumor heterogeneity of both estrogen receptor (ER) and HER2 expression has been proposed to play a key role in treatment failure, but little work has been done to comprehensively study this heterogeneity at the single-cell level. In this study, we explored the clinical impact of intratumor heterogeneity of ER protein expression, HER2 protein expression, and HER2 gene copy number alterations. Using combined immunofluorescence and in situ hybridization on tissue sections followed by a validated computational approach, we analyzed more than 13 000 single tumor cells across 37 HER2+ breast tumors. The samples were taken both before and after neoadjuvant chemotherapy plus HER2-targeted treatment, enabling us to study tumor evolution as well. We found that intratumor heterogeneity for HER2 copy number varied substantially between patient samples. Highly heterogeneous tumors were associated with significantly shorter disease-free survival and fewer long-term survivors. Patients for which HER2 characteristics did not change during treatment had a significantly worse outcome. This work shows the impact of intratumor heterogeneity in molecular diagnostics for treatment selection in HER2+ breast cancer patients and the power of computational scoring methods to evaluate in situ molecular markers in tissue biopsies.

Glucocorticoids promote transition of ductal carcinoma in situ to invasive ductal carcinoma by inducing myoepithelial cell apoptosis

BACKGROUND

The microenvironment and stress factors like glucocorticoids have a strong influence on breast cancer progression but their role in the first stages of breast cancer and, particularly, in myoepithelial cell regulation remains unclear. Consequently, we investigated the role of glucocorticoids in ductal carcinoma in situ (DCIS) in breast cancer, focusing specially on myoepithelial cells.

METHODS

To clarify the role of glucocorticoids at breast cancer onset, we evaluated the effects of cortisol and corticosterone on epithelial and myoepithelial cells using 2D and 3D in vitro and in vivo approaches and human samples.

RESULTS

Glucocorticoids induce a reduction in laminin levels and favour the disruption of the basement membrane by promotion of myoepithelial cell apoptosis in vitro. In an in vivo stress murine model, increased corticosterone levels fostered the transition from DCIS to invasive ductal carcinoma (IDC) via myoepithelial cell apoptosis and disappearance of the basement membrane. RU486 is able to partially block the effects of cortisol in vitro and in vivo. We found that myoepithelial cell apoptosis is more frequent in patients with DCIS+IDC than in patients with DCIS.

CONCLUSIONS

Our findings show that physiological stress, through increased glucocorticoid blood levels, promotes the transition from DCIS to IDC, particularly by inducing myoepithelial cell apoptosis. Since this would be a prerequisite for invasive features in patients with DCIS breast cancer, its clinical management could help to prevent breast cancer progression to IDC.

Differential expression of neurogenes among breast cancer subtypes identifies high risk patients

The nervous system is now recognized to be a relevant component of the tumor microenvironment. Receptors for neuropeptides and neurotransmitters have been identified in breast cancer. However, very little is known about the role of neurogenes in regulating breast cancer progression. Our purpose was to identify neurogenes associated with breast cancer tumorigenesis with a potential to be used as biomarker and/or targets for treatment. We used three databases of human genes: GeneGo, GeneCards and Eugenes to generate a list of 1266 relevant neurogenes. Then we used bioinformatics tools to interrogate two published breast cancer databases SAGE and MicMa (n=96) and generated a list of 7 neurogenes that are differentially express among breast cancer subtypes. The clinical potential was further investigated using the GOBO database (n=1881). We identified 6 neurogenes that are differentially expressed among breast cancer subtypes and whose expression correlates with prognosis. Histamine receptor1 (HRH1), neuropilin2 (NRP2), ephrin-B1 (EFNB1), neural growth factor receptor (NGFR) and amyloid precursor protein (APP) were differentially overexpressed in basal and HER2-enriched tumor samples and syntaxin 1A (STX1A) was overexpressed in HER2-enriched and luminal B tumors. Analysis of HRH1, NRP2, and STX1A expression using the GOBO database showed that their expression significantly correlated with a shorter overall survival (p < 0.0001) and distant metastasis-free survival (p < 0.0001). In contrast, elevated co-expression of NGFR, EFNB1 and APP was associated with longer overall (p < 0.0001) and metastasis-free survival (p < 0.0001). We propose that HRH1, NRP2, and STX1A can be used as prognostic biomarkers and therapeutic targets for basal and HER2-enriched breast cancer subtypes.

Abstract 752: Fibroblast growth factor receptor 2 - HER2 transactivation: Role of fbroblasts in the acquisition and maintenance of anti-Her2 target therapies resistance in breast cancer

INTRODUCTION

Mechanisms underlying tumor progression after chemotherapy are not well understood. Therapeutic treatments can favor the clonal selection of cells with unique properties and different fitness for a given microenvironment. Indeed, tumor cells can induce changes in the structure and composition of the microenvironment to support their growth and spread.

Our aim is to study if clonal selection induced by target therapies like Trastuzumab and Lapatinib favors the outgrowth of cells with different microenvironmental crosstalk capability, and in particular the role of fibroblast in the selection of these particular clones.

MATERIALS AND METHODS

We developed different cell lines resistant to these drugs from the parental SKBR3, BT474 and MDA-MB-453 Her2+ cells lines. We determined their molecular profile and investigated the changes in the expression of selected genes codifying soluble factors known to induce stromal changes, like chemokines, cytokines, matrix remodeling-related enzymes, angiogenic and neurogenic factors.

To study the role of fibroblast in the selection of the resistant clones, and the crosstalk between these two populations, we developed fibroblast immortalized lines derived from breast cancer tumors and normal breast tissue, and study the effect of the fibroblasts in resistant induction, as well as the effect of resistant clones in the fibroblast activation.

RESULTS AND DISCUSION

We found that factors secreted by fibroblast can support cancer growth and progression by influencing and promoting the resistant phenotype. In our proposed model, HER2 positive BC cell lines resistant to Trastuzumab and Lapatinib have an active FGFR2 signalling pathway, able to maintain HER2 signalling by receptor transactivation. This bypasses HER2 inhibition and contributes to the maintenance of the cellular addiction to HER2 pathways even when the protein is being targeted, promoting cell proliferation and survival. Moreover, resistant cell lines secreted factors induced fibroblast activation and also modulated fibroblasts tumour promoting factors secretion pattern. As a result, after exposure to resistant cell lines secreted factors, fibroblasts become more efficient on promoting BC cell lines resistance. Similarly, the supernatant derived from fibroblasts isolated from HER2+ tumours was able to induce the activation of HER2 and FGFR2 pathways. The same effect was found in vivo, were co-injection with HER2+ tumour associated fibroblasts promoted tumour aggressiveness and resistance through HER2 and FGFR2 activation

CONCLUSION

These results highlight the importance of microenvironment in supporting tumor progression after chemotherapy.

Citation Format: Patricia Fernandez Nogueira, Mario Mancino, Gemma Fuster, Estel Enreig, Elisabeth Ametller, Paloma Bragado, Vanessa Almendro, Pedro Gascón, Pedro Gascón. Fibroblast growth factor receptor 2 - HER2 transactivation: Role of fbroblasts in the acquisition and maintenance of anti-Her2 target therapies resistance in breast cancer. [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 752.

The Proliferative Activity of Mammary Epithelial Cells in Normal Tissue Predicts Breast Cancer Risk in Premenopausal Women

The frequency and proliferative activity of tissue-specific stem and progenitor cells are suggested to correlate with cancer risk. In this study, we investigated the association between breast cancer risk and the frequency of mammary epithelial cells expressing p27, estrogen receptor (ER), and Ki67 in normal breast tissue. We performed a nested case-control study of 302 women (69 breast cancer cases, 233 controls) who had been initially diagnosed with benign breast disease according to the Nurses' Health Studies. Immunofluorescence for p27, ER, and Ki67 was performed on tissue microarrays constructed from benign biopsies containing normal mammary epithelium and scored by computational image analysis. We found that the frequency of Ki67(+) cells was positively associated with breast cancer risk among premenopausal women [OR = 10.1, 95% confidence interval (CI) = 2.12-48.0]. Conversely, the frequency of ER(+) or p27(+) cells was inversely, but not significantly, associated with subsequent breast cancer risk (ER(+): OR = 0.70, 95% CI, 0.33-1.50; p27(+): OR = 0.89, 95% CI, 0.45-1.75). Notably, high Ki67(+)/low p27(+) and high Ki67(+)/low ER(+) cell frequencies were significantly associated with a 5-fold higher risk of breast cancer compared with low Ki67(+)/low p27(+) and low Ki67(+)/low ER(+) cell frequencies, respectively, among premenopausal women (Ki67(hi)/p27(lo): OR = 5.08, 95% CI, 1.43-18.1; Ki67(hi)/ER(lo): OR = 4.68, 95% CI, 1.63-13.5). Taken together, our data suggest that the fraction of actively cycling cells in normal breast tissue may represent a marker for breast cancer risk assessment, which may therefore impact the frequency of screening procedures in at-risk women. Cancer Res; 76(7); 1926-34. ©2016 AACR.

Abstract B69: Acquisition and maintenance of anti-Her2 target therapies resistance in breast cancer: Role of fibrobroblasts

Introduction: Mechanisms underlying tumor progression after chemotherapy are not well understood. Therapeutic treatments can favor the clonal selection of cells with unique properties and different fitness for a given microenvironment. Indeed, tumor cells can induce changes in the structure and composition of the microenvironment to support their growth and spread.

Our aim is to study if clonal selection induced by target therapies like Trastuzumab and Lapatinib favors the outgrowth of cells with different microenvironmental crosstalk capability, and in particular the role of fibroblast in the selection of these particular clones.

Materials and Methods: In order to investigate if clonal selection induced by target therapies like Trastuzumab and Lapatinib favors the outgrowth of cells with different capability of microenvironmental crosstalk, we developed different cell lines resistant to these drugs from the parental SKBR3, BT474 and MDA-MB-453 Her2+ cells lines. We determined their molecular profile and investigated the changes in the expression of selected genes codifying soluble factors known to induce stromal changes, like chemokines, cytokines, matrix remodeling-related enzymes, angiogenic and neurogenic factors.

To study the role of fibroblast in the selection of the resistant clones, and the crosstalk between these two populations, we developed fibroblast immortalized lines derived from breast cancer tumors and normal breast tissue, and study the effect of the fibroblasts in resistant induction, as well as the effect of resistant clones in the fibroblast activation.

Results and Discussion: We observed that the major changes in the genes investigated were obtained in the Lapatinib resistant cell lines, suggesting that the acquisition of Lapatinib resistance can provide the tumor with a higher capability of stromal interaction. In vivo, the resistant cell lines showed an invasive growth pattern and higher angiogenesis compared to the parental cell lines. We observed a different pattern of fibroblast distribution in the tumors derived from the resistant cell lines, which display a more infiltrative distribution. The resistant tumors were also more fibroblast-enriched suggesting a higher microenvironment crosstalk capacity. In vitro, we found that the supernatant of breast cancer associated fibroblast was able to induce an increase in the resistant phenotype of parental lines, and that the resistant cell lines were able to induce a slightly activation of fibroblasts.

Conclusion: These results highlight the importance of microenvironment in supporting tumor progression after chemotherapy.

Citation Format: Patricia Fernandez-Nogueira, Mario Mancino, Gemma Fuster, Estel Enreig, Elisabeth Ametller, Paloma Bragado, Vanessa Almendro, Pere Gascon. Acquisition and maintenance of anti-Her2 target therapies resistance in breast cancer: Role of fibrobroblasts. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr B69.

Abstract PR05: The effect of chemotherapy on HER2+ breast cancer heterogeneity measured by STAR-FISH: Detection of PIK3CA mutation and HER2 amplification at single-cell level in situ

Current therapies in HER2-positive breast cancer are effective in only a subset of cases and part of the resistance is attributed to single nucleotide mutation H1047R in PIK3CA. Conventional PIK3CA mutation detection methods require isolation of DNA from the tumor bulk, which requires relatively large amount of tissue and may not detect mutations in rare cancer cells.

We developed a novel method, Specific-To-Allele PCR-FISH (STAR-FISH), which allows for in situ detection of point mutation and gene amplification at single cell level. The assay consists of in situ PCR steps with mutation specific primers, followed by hybridization of a fluorescently labeled DNA probe homologous to PCR primer overhangs and probes for genomic regions of interest. The STAR-FISH signals present in intact formalin-fixed paraffin embedded (FFPE) samples are imaged and quantified in each individual nucleus within a tissue, with false discovery rate at 0.001, which facilitates identification of sub-populations of cells with different genetic makeup. The method was validated against FACS, immunofluorescence, droplet digital PCR, and MassArray; high correlation of the results was observed (R2=0.901 -0.9037, p&lt;0.001).

We applied STAR-FISH for PIK3CA hot-spot mutation and HER2 amplification to FFPE samples of HER2 positive breast tumors from 22 patients. For each case a chemotherapy naïve core needle biopsy and a post-neoadjuvant chemotherapy sample upon tumor resection were collected. STAR-FISH analysis was performed on 3-5 regions of each sample, to account for intratumor heterogeneity. Long-term patient survival data after adjuvant treatment, mostly with trastuzumab, were available for all the patients.

High-sensitivity of STAR-FISH allowed us to detect rare single cells carrying PIK3CA mutation in most of the pre-treatment samples. After adjuvant chemotherapy the frequency of these cells was significantly increased. Since the STAR-FISH signals are quantified in each individual nucleus, subpopulations of cells with PIK3CA mutation or HER2 amplification or both features can be distinguished. Based on frequencies of cells within each of these subpopulations we calculated Shannon diversity index for each pre- and post-chemotherapy sample. The index was significantly increased after treatment. However, only topologic and not overall changes in diversity predicted poor long-term survival of the patients.

In addition to analyzing the frequency of cells with PIK3CA mutation, HER2 amplification or both changes, STAR-FISH also assesses the spatial distribution of genetically distinct subtypes. We have found that cells with PIK3CA mutation, irrespective of their HER2 status, are much more dispersed within tumors after neaodjuvant chemotherapy, whereas cells with HER2 amplification and wild-type PIK3CA cluster together. These results suggest that PIK3CA mutant cells are more migratory and invasive, in agreement with prior studies of cell lines and animal models.

STAR-FISH provides a unique view into genetic intratumor heterogeneity since thousands of cells within different regions of a single tumor biopsy can be analyzed within their tissue environment. Application of this novel in situ method allowed us to detect rare cells with PIK3CA mutation, pre-existing in the majority of treatment-naïve tumors and increasing in frequency after neoadjuvant chemotherapy. Moreover, STAR-FISH data revealed the correlation of chemotherapy-induced changes in intratumor heterogeneity with long-term survival of HER2+ breast cancer patients and support the significance of tumor diversity in situ analyses.

Citation Format: Michalina Janiszewska, Lin Liu, Vanessa Almendro, Yanan Kuang, Cloud Paweletz, Britta Weigelt, Rita A. Sakr, Tari A. King, Sarat Chandarlapaty, Jorge S. Reis-Filho, Ariella B. Hanker, Carlos L. Arteaga, Park So Yeon, Franziska Michor, Kornelia Polyak. The effect of chemotherapy on HER2+ breast cancer heterogeneity measured by STAR-FISH: Detection of PIK3CA mutation and HER2 amplification at single-cell level in situ. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr PR05.

In situ single-cell analysis identifies heterogeneity for PIK3CA mutation and HER2 amplification in HER2-positive breast cancer

Detection of minor, genetically distinct subpopulations within tumors is a key challenge in cancer genomics. Here we report STAR-FISH (specific-to-allele PCR-FISH), a novel method for the combined detection of single-nucleotide and copy number alterations in single cells in intact archived tissues. Using this method, we assessed the clinical impact of changes in the frequency and topology of PIK3CA mutation and HER2 (ERBB2) amplification within HER2-positive breast cancer during neoadjuvant therapy. We found that these two genetic events are not always present in the same cells. Chemotherapy selects for PIK3CA-mutant cells, a minor subpopulation in nearly all treatment-naive samples, and modulates genetic diversity within tumors. Treatment-associated changes in the spatial distribution of cellular genetic diversity correlated with poor long-term outcome following adjuvant therapy with trastuzumab. Our findings support the use of in situ single cell-based methods in cancer genomics and imply that chemotherapy before HER2-targeted therapy may promote treatment resistance.

The Transmodulation of HER2 and EGFR by Substance P in Breast Cancer Cells Requires c-Src and Metalloproteinase Activation

Background

Substance P (SP) is a pleiotropic cytokine/neuropeptide that enhances breast cancer (BC) aggressiveness by transactivating tyrosine kinase receptors like EGFR and HER2. We previously showed that SP and its cognate receptor NK-1 (SP/NK1-R) signaling modulates the basal phosphorylation of HER2 and EGFR in BC, increasing aggressiveness and drug resistance. In order to elucidate the mechanisms responsible for NK-1R-mediated HER2 and EGFR transactivation, we investigated the involvement of c-Src (a ligand-independent mediator) and of metalloproteinases (ligand-dependent mediators) in HER2/EGFR activation.

Results and Discussion

Overexpression of NK-1R in MDA-MB-231 and its chemical inhibition in SK-BR-3, BT-474 and MDA-MB-468 BC cells significantly modulated c-Src activation, suggesting that this protein is a mediator of NK-1R signaling. In addition, the c-Src inhibitor 4-(4’-phenoxyanilino)-6,7-dimethoxyquinazoline prevented SP-induced activation of HER2. On the other hand, SP-dependent phosphorylation of HER2 and EGFR decreased substantially in the presence of the MMP inhibitor 1–10, phenanthroline monohydrate, and the dual inhibition of both c-Src and MMP almost abolished the activation of HER2 and EGFR. Moreover, the use of these inhibitors demonstrated that this Src and MMP-dependent signaling is important to the cell viability and migration capacity of HER2+ and EGFR+ cell lines.

Conclusion

Our results indicate that the transactivation of HER2 and EGFR by the pro-inflammatory cytokine/neuropeptide SP in BC cells is a c-Src and MMP-dependent process.

Comparison of methods for the isolation of human breast epithelial and myoepithelial cells

Two lineages, epithelial, and myoepithelial cells are the main cell populations in the normal mammary gland and in breast cancer. Traditionally, cancer research has been performed using commercial cell lines, but primary cell cultures obtained from fresh breast tissue are a powerful tool to study more reliably new aspects of mammary gland biology, including normal and pathological conditions. Nevertheless, the methods described to date have some technical problems in terms of cell viability and yield, which hamper work with primary mammary cells. Therefore, there is a need to optimize technology for the proper isolation of epithelial and myoepithelial cells. For this reason, we compared four methods in an effort to improve the isolation and primary cell culture of different cell populations of human mammary epithelium. The samples were obtained from healthy tissue of patients who had undergone mammoplasty or mastectomy surgery. We based our approaches on previously described methods, and incorporated additional steps to ameliorate technical efficiency and increase cell survival. We determined cell growth and viability by phase-contrast images, growth curve analysis and cell yield, and identified cell-lineage specific markers by flow cytometry and immunofluorescence in 3D cell cultures. These techniques allowed us to better evaluate the functional capabilities of these two main mammary lineages, using CD227/K19 (epithelial cells) and CD10/K14 (myoepithelial cells) antigens. Our results show that slow digestion at low enzymatic concentration combined with the differential centrifugation technique is the method that best fits the main goal of the present study: protocol efficiency and cell survival yield. In summary, we propose some guidelines to establish primary mammary epithelial cell lines more efficiently and to provide us with a strong research instrument to better understand the role of different epithelial cell types in the origin of breast cancer.

GoIFISH: a system for the quantification of single cell heterogeneity from IFISH images

Molecular analysis has revealed extensive intra-tumor heterogeneity in human cancer samples, but cannot identify cell-to-cell variations within the tissue microenvironment. In contrast, in situ analysis can identify genetic aberrations in phenotypically defined cell subpopulations while preserving tissue-context specificity. GoIFISHGoIFISH is a widely applicable, user-friendly system tailored for the objective and semi-automated visualization, detection and quantification of genomic alterations and protein expression obtained from fluorescence in situ analysis. In a sample set of HER2-positive breast cancers GoIFISHGoIFISH is highly robust in visual analysis and its accuracy compares favorably to other leading image analysis methods. GoIFISHGoIFISH is freely available at www.sourceforge.net/projects/goifish/.

The neurokinin-1 receptor antagonist aprepitant is a promising candidate for the treatment of breast cancer

The substance P (SP)/neurokinin (NK)-1 receptor system plays an important role in the development of cancer. No in-depth studies of the involvement of this system in breast cancer (BC) have been carried out, and the action exerted by the drug aprepitant on BC cells is currently unknown. We show the involvement of this system in human BC cell lines: i) these cells express mRNA for the NK-1 receptor; ii) they overexpress NK-1 receptors; iii) the NK-1 receptor is involved in their viability; iv) SP induces their proliferation; v) NK-1 receptor antagonists block SP-induced mitogen stimulation of these cells; vi) the specific antitumor action of such antagonists on these cells occurs through the NK-1 receptor; and vii) BC cell death is due to apoptosis. We also found NK-1 receptors and SP in all human BC samples studied. The NK-1 receptor may be a promising target in the treatment of BC and NK-1 receptor antagonists could be candidates as a new antitumor drug in the treatment of BC.

JARID1B is a luminal lineage-driving oncogene in breast cancer

Recurrent mutations in histone-modifying enzymes imply key roles in tumorigenesis, yet their functional relevance is largely unknown. Here, we show that JARID1B, encoding a histone H3 lysine 4 (H3K4) demethylase, is frequently amplified and overexpressed in luminal breast tumors and a somatic mutation in a basal-like breast cancer results in the gain of unique chromatin binding and luminal expression and splicing patterns. Downregulation of JARID1B in luminal cells induces basal genes expression and growth arrest, which is rescued by TGFβ pathway inhibitors. Integrated JARID1B chromatin binding, H3K4 methylation, and expression profiles suggest a key function for JARID1B in luminal cell-specific expression programs. High luminal JARID1B activity is associated with poor outcome in patients with hormone receptor-positive breast tumors.

Inference of tumor evolution during chemotherapy by computational modeling and in situ analysis of genetic and phenotypic cellular diversity

Cancer therapy exerts a strong selection pressure that shapes tumor evolution, yet our knowledge of how tumors change during treatment is limited. Here, we report the analysis of cellular heterogeneity for genetic and phenotypic features and their spatial distribution in breast tumors pre- and post-neoadjuvant chemotherapy. We found that intratumor genetic diversity was tumor-subtype specific, and it did not change during treatment in tumors with partial or no response. However, lower pretreatment genetic diversity was significantly associated with pathologic complete response. In contrast, phenotypic diversity was different between pre- and posttreatment samples. We also observed significant changes in the spatial distribution of cells with distinct genetic and phenotypic features. We used these experimental data to develop a stochastic computational model to infer tumor growth patterns and evolutionary dynamics. Our results highlight the importance of integrated analysis of genotypes and phenotypes of single cells in intact tissues to predict tumor evolution.

Genetic and phenotypic diversity in breast tumor metastases

Metastatic disease is the main cause of cancer-related mortality due to almost universal therapeutic resistance. Despite its high clinical relevance, our knowledge of how cancer cell populations change during metastatic progression is limited. Here, we investigated intratumor genetic and phenotypic heterogeneity during metastatic progression of breast cancer. We analyzed cellular genotypes and phenotypes at the single cell level by performing immunoFISH in intact tissue sections of distant metastatic tumors from rapid autopsy cases and from primary tumors and matched lymph node metastases collected before systemic therapy. We calculated the Shannon index of intratumor diversity in all cancer cells and within phenotypically distinct cell populations. We found that the extent of intratumor genetic diversity was similar regardless of the chromosomal region analyzed, implying that it may reflect an inherent property of the tumors. We observed that genetic diversity was highest in distant metastases and was generally concordant across lesions within the same patient, whereas treatment-naïve primary tumors and matched lymph node metastases were frequently genetically more divergent. In contrast, cellular phenotypes were more discordant between distant metastases than primary tumors and matched lymph node metastases. Diversity for 8q24 was consistently higher in HER2(+) tumors compared with other subtypes and in metastases of triple-negative tumors relative to primary sites. We conclude that our integrative method that couples ecologic models with experimental data in human tissue samples could be used for the improved prognostication of patients with cancer and for the design of more effective therapies for progressive disease.

Abstract A150: A methodology for the isolation, culture, and immortalization of human breast epithelial and myoepithelial cells

Introduction: Breast tissue is composed by different cell types including epithelial and myoepithelial cells, macrophages, fibroblasts, adipocytes, and cells from the immune system. Two main lineages, epithelial and myoepithelial cells, are the most essential cell populations in the normal mammary gland and also in breast cancer. Traditionally, cancer research has been performed using commercial cell lines, but primary cell cultures suppose a powerful tool to study with a higher reliability new aspects of mammary gland biology including normal and diseased tissue. However, normal primary human epithelial cells in culture achieve senescence at 10 to 40 population doubling, hampering their long-term culture. In addition, some studies have described lineage-specific marker limitations to be used in order to isolate these two cell types, since some of the markers tend to change during cell culture.

Experimental Procedures: In this protocol we compared two different methodologies in an effort to improve isolation, culture and immortalization of different cell populations of human normal mammary epithelium. We based our approaches in previously described methods incorporating additional steps to improve cell survival, to preserve cellular antigens used for isolation and validation of cell subpopulations and to enhance cellular transformation. For these purposes, we determined cell growth and viability, and also cell-lineage specific markers of cytospinned cells in both methodologies used.

Results: One of the goals of the present work to yield on cell survival and antigens preservation is in fact overnight digestion at low enzymatic concentration. Other crucial steps are cell immortalization and also addition of critical compounds to the cell culture media.

Conclusions: In the present work, we propose some guidelines to establish more efficiently mammary epithelial cell lines allowing long-term cell culture system and providing us a strong instrument to better understand the role of the different epithelial cell types and the origins of breast cancer.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A150.

Citation Format: Gemma Fuster, Arantzazu Zubeldia-Plazaola, Mario Mancino, Patricia Fernández-Nogueira, Elisabet Ametller, Pedro Gascón, Vanessa Almendro. A methodology for the isolation, culture, and immortalization of human breast epithelial and myoepithelial cells. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A150.

Substance P autocrine signaling contributes to persistent HER2 activation that drives malignant progression and drug resistance in breast cancer

ERBB receptor transmodulation by heterologous G-protein-coupled receptors (GPCR) generates functional diversity in signal transduction. Tachykinins are neuropeptides and proinflammatory cytokines that promote cell survival and cancer progression by activating several GPCRs. In this work, we found that the pain-associated tachykinin Substance P (SP) contributes to persistent transmodulation of the ERBB receptors, EGFR and HER2, in breast cancer, acting to enhance malignancy and therapeutic resistance. SP and its high-affinity receptor NK-1R were highly expressed in HER2(+) primary breast tumors (relative to the luminal and triple-negative subtypes) and were overall correlated with poor prognosis factors. In breast cancer cell lines and primary cultures derived from breast cancer samples, we found that SP could activate HER2. Conversely, RNA interference-mediated attenuation of NK-1R, or its chemical inhibition, or suppression of overall GPCR-mediated signaling, all strongly decreased steady-state expression of EGFR and HER2, establishing that their basal activity relied upon transdirectional activation by GPCR. Thus, SP exposure affected cellular responses to anti-ERBB therapies. Our work reveals an important oncogenic cooperation between NK-1R and HER2, thereby adding a novel link between inflammation and cancer progression that may be targetable by SP antagonists that have been clinically explored.

Abstract A60: Activation of compensatory receptor tyrosine kinases after the acquisition of resistance to anti-Her2 therapies

Background: Acquired resistance to therapy is a main obstacle in the success of cancer treatment. In HER2+ breast cancer (BC) patient survival has raised considerably after the introduction of the anti-target therapies Trastuzumab and Lapatinib. However, a considerable number of patients develop resistance to anti-HER2 therapies by HER2-related and unrelated mechanisms. Cancer cells displaying HER2 overexpression initially rely on the oncogenic addiction for HER2-controlled survival signaling pathways. However, the fact that some tumors resistant to anti-HER2 therapies still present HER2 amplification suggest the activation of compensatory pathways for the control of cell survival.

Objectives: We aimed to identify compensatory survival pathways activated after the acquisition of resistance to Trastuzumab and Lapatinib that could be therapeutically targeted to overcome resistance to anti-HER2 therapies. We focus our efforts in identifying activated RTKs given that they are easily targetable proteins.

Experimental Procedures: To identify compensatory pathways related to tumor escape to anti-HER2 therapies we developed an in vitro model of drug resistance by continuous exposure of the MDA-MB-453, BT474, and SKBR3 cell lines to increased concentrations of Trastuzumab or Lapatinib for over 6 months. Activated RTKs were identified by a phosphoproteome array, and their role in cell survival in cell lines resistant to anti-HER2 therapies was validated by siRNA and chemical inhibition experiments.

Results: The resistant phenotype of the cell lines was confirmed by determining cell proliferation and apoptosis upon drug treatment. Moreover, the resistant cell lines displayed the more aggressive biological behavior in vitro and in vivo, as evidenced by the increased clonogenic ability and their tumorigenicity in immmunosupressed mice. We did not observed changes in the copy number of 17q12 (HER2) or 7p12 (EGFR) by FISH or in the mRNA levels by qPCR in any of the resistant cell lines, although there was a significant increase in the protein levels as determined by immunohistochemistry. By phosphoproteome array we identified the activation of several RTKs. The INGENUITY pathway analysis of the receptors identified indicated a main relevance for the processes related to cell signaling and cell cycle, cellular growth and proliferation, and more interestingly with axonal guidance signaling and human embryonic stem cell pluripotency. To confirm the involvement of those receptors in the activation of compensatory pathways in Trastuzumab and Lapatinib resistant cell lines, we performed a chemical screening. We further validated the involvement of several receptors in cell survival by siRNA.

Conclusion: Several compensatory pathways for cell survival are activated after the acquisition of resistance to Trastuzumab and Lapatinib. The inhibition of such pathways could be used a new therapeutic approach for the treatment of resistant tumors, or to avoid the development of resistant cells.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A60.

Citation Format: Patricia Fernandez Nogueira, Anke Bill, Inga Rye, Domiziana Costamagna, Hege Russnes, Pedro Gascón, Alex Gaither, Vanessa Almendro. Activation of compensatory receptor tyrosine kinases after the acquisition of resistance to anti-Her2 therapies. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A60.

Abstract C47: Inference of tumor evolution during chemotherapy by computational modeling and single cell analysis of diversity

Cancer therapy exerts a strong selection that shapes tumor evolution, yet our knowledge of how tumors change during treatment is limited. Here we report the analysis of single-cell heterogeneity of genetic and phenotypic features and their spatial distribution in breast tumors pre and post neoadjuvant therapy. We found that broad intratumor genetic diversity is tumor subtype specific but does not change significantly during treatment. However, we observed significant alterations in the spatial distribution of cells after chemotherapy whereas adjacent tumor cells were more likely to be genetically divergent yet phenotypically similar. We then developed a stochastic computational model to infer tumor growth patterns and evolutionary dynamics from these topologic features. Lastly, we found that lower pretreatment genetic diversity is associated with a better response, emphasizing the clinical utility of our study. Our results highlight the importance of an integrated analysis of genotype and phenotype of single cells in intact tissue to predict how tumors evolve.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C47.

Citation Format: Vanessa Almendro, Yu-Kang Cheng, Mithat Gönen, Shalev Itzkovitz, Andriy Marusyk, Elisabet Ametller, Xavier Gonzalez-Farre, Montse Muñoz, Hege Russnes, Åslaug Helland, Inga Rye, Anne Lise Borresen-Dale, Reo Maruyama, Alexander van Oudenaarden, Mitchell Dowsett, Robin L. Jones, Jorge Reis-Filho, Pere Gascon, Franziska Michor, Kornelia Polyak. Inference of tumor evolution during chemotherapy by computational modeling and single cell analysis of diversity. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C47.

Abstract B100: Subtype specific expression of HRH1 contributes to increased chemoresistance of breast cancer cells

Background: Histamine is a monoamine produced by α-decarboxylation of histidine by the enzyme histidine decarboxylase (HDC). Histamine acts as an autocrine regulator of cell proliferation through its binding to HRH1-4 receptors. In breast cancer (BC), there are controversial results about the therapeutic efficacy of HRH1 or HRH2 inhibitors and the role of histamine receptors in tumor progression.

Given the phenotypic heterogeneity of BC and the presence of different molecular subtypes with different clinical outcome, we aimed to investigate the contribution of histamine receptors in the proliferation, migration and cell survival of BC cells of different molecular subtypes.

Methods: The expression of histamine receptors HRH1-4 and HDC in human breast tumors of different subtypes, and their correlation with clinical variables were gathered through informatics analysis using the “Gene expression based Outcome for Breast cancer Online” (GOBO) web-based tool. The measurement of the mRNA levels of HRH1-4 and HDC in a panel of breast cancer cell lines was used to confirm the subtype specific expression of each protein. Using specific HRH inhibitors in luminal and basal-like breast cancer cell lines we assessed the functional role of histamine receptors in cell proliferation, migration and survival.

Results: HRH1 was highly expressed in ER+ tumors while HDC was highly expressed in the ER- tumors. In any case, the high expression of HRH1 or HDC was significantly correlated with lower overall survival only in ER+ tumors. The same pattern of expression was observed in BC cell lines, where HRH1 was highly expressed in basal-like BC cells compared to the luminal ones. HRH2 and HRH3 were highly expressed in the estrogen-dependent MCF7 cell line, while HRH4 was not detected in any breast cancer cell line. Only the antagonism of HRH1 induced apoptosis, and decreased proliferation and migration, while HRH2 or HRH3 inhibition had no effect on cell survival. Interestingly, the luminal cell lines were more sensitive than the basal-like cell lines to HRH1 antagonism, even though the low expression of HRH1 in these cells.

Conclusion: Taken together, these findings suggest a complex role of the autocrine histamine signaling system in the progression of BC tumors of different subtype through the activation of HRH1.

Citation Format: Mario Mancino, Patricia Fernandez-Nogueira, Estel Enreig, Elisabet Ametller, Pedro Gascón, Vanessa Almendro. Subtype specific expression of HRH1 contributes to increased chemoresistance of breast cancer cells. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr B100.

Abstract P3-05-04: Intra-tumor heterogeneity as a predictor of therapy response in HER2 positive breast cancer

Background: Breast cancer is known to be a heterogeneous disease both at the clinical and molecular level. In addition, heterogeneity can also exist within a given tumor, and subpopulations can have distinct phenotypic and genomic features. Little is known about the relationship between intra-tumor heterogeneity and prediction of response to treatment. This study aimed at using a combination of immunofluorescence and fluorescence in situ (FISH) technique (“double immunoFISH”) to identify intra-tumor heterogeneity in tumors from neo-adjuvant treated patients prior to and after therapy, searching for features predicting the response to neo adjuvant treatment.

Material and methods: Twentytwo patients diagnosed with HER2 positive, neo-adjuvant treated breast cancer ((3–4 FEC100 followed by 4 docetaxel plus trastuzumab, 3qw) were selected. Half of the patients had complete response and the others had partial response. By double immunoFISH both phenotypic (ER and HER2 protein) and genomic changes (copy number of HER2 gene and centromere 17) were assessed in the same cells simultaneously on biopsies before and after treatment. The samples were photographed in a Zeiss Axio Imager M1 with 5 fluorescence channels and analyzed with axiovision software. The intensity and localization of HER2 and ER immunofluorescence were semi-quantitatively estimated while the HER2 and centromere 17 FISH signals were counted in 100 cells.

Results: The patients with partial response displayed a high grade of cell-to-cell diversity regarding HER2 copy number, nuclear shape and size and the expression of the membrane protein HER2. This was in contrast to the results from the complete responders who showed a reduced diversity and were more frequently ER negative. In the patients with partial response, a higher diversity was seen after treatment.

Conclusion: The genomic variability prior to therapy was higher in the partial-responders vs. the complete responders, and the remaining tumor was even more heterogeneous after treatment than prior to treatment. Double immunoFISH is a valuable tool for visualization of both phenotypic and genomic alterations in the same cell in FFPE sections. The cohort will be expanded to explore the diversity further, and the results will be presented.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-05-04.

Cellular heterogeneity and molecular evolution in cancer

Intratumor heterogeneity represents a major obstacle to effective cancer treatment and personalized medicine. However, investigators are now elucidating intratumor heterogeneity at the single-cell level due to improvements in technologies. Better understanding of the composition of tumors, and monitoring changes in cell populations during disease progression and treatment, will improve cancer diagnosis and therapeutic design. Measurements of intratumor heterogeneity may also be used as biomarkers to predict the risk of progression and therapeutic resistance. We summarize important considerations related to intratumor heterogeneity during tumor evolution. We also discuss experimental approaches that are commonly used to infer intratumor heterogeneity and describe how these methodologies can be translated into clinical practice.

Amplified loci on chromosomes 8 and 17 predict early relapse in ER-positive breast cancers

Adjuvant hormonal therapy is administered to all early stage ER+ breast cancers, and has led to significantly improved survival. Unfortunately, a subset of ER+ breast cancers suffer early relapse despite hormonal therapy. To identify molecular markers associated with early relapse in ER+ breast cancer, an outlier analysis method was applied to a published gene expression dataset of 268 ER+ early-stage breast cancers treated with tamoxifen alone. Increased expression of sets of genes that clustered in chromosomal locations consistent with the presence of amplicons at 8q24.3, 8p11.2, 17q12 (HER2 locus) and 17q21.33-q25.1 were each found to be independent markers for early disease recurrence. Distant metastasis free survival (DMFS) after 10 years for cases with any amplicon (DMFS  = 56.1%, 95% CI  = 48.3–63.9%) was significantly lower (P  = 0.0016) than cases without any of the amplicons (DMFS  = 87%, 95% CI  = 76.3% –97.7%). The association between presence of chromosomal amplifications in these regions and poor outcome in ER+ breast cancers was independent of histologic grade and was confirmed in independent clinical datasets. A separate validation using a FISH-based assay to detect the amplicons at 8q24.3, 8p11.2, and 17q21.33-q25.1 in a set of 36 early stage ER+/HER2- breast cancers treated with tamoxifen suggests that the presence of these amplicons are indeed predictive of early recurrence. We conclude that these amplicons may serve as prognostic markers of early relapse in ER+ breast cancer, and may identify novel therapeutic targets for poor prognosis ER+ breast cancers.

Intra-tumour heterogeneity: a looking glass for cancer?

Populations of tumour cells display remarkable variability in almost every discernable phenotypic trait, including clinically important phenotypes such as ability to seed metastases and to survive therapy. This phenotypic diversity results from the integration of both genetic and non-genetic influences. Recent technological advances have improved the molecular understanding of cancers and the identification of targets for therapeutic interventions. However, it has become exceedingly apparent that the utility of profiles based on the analysis of tumours en masse is limited by intra-tumour genetic and epigenetic heterogeneity, as characteristics of the most abundant cell type might not necessarily predict the properties of mixed populations. In this Review, we discuss both genetic and non-genetic causes of phenotypic heterogeneity of tumour cells, with an emphasis on heritable phenotypes that serve as a substrate for clonal selection. We discuss the implications of intra-tumour heterogeneity in diagnostics and the development of therapeutic resistance.

Evolutionary pathways in BRCA1-associated breast tumors

BRCA1-associated breast tumors display loss of BRCA1 and frequent somatic mutations of PTEN and TP53. Here we describe the analysis of BRCA1, PTEN, and p53 at the single cell level in 55 BRCA1-associated breast tumors and computational methods to predict the relative temporal order of somatic events, on the basis of the frequency of cells with single or combined alterations. Although there is no obligatory order of events, we found that loss of PTEN is the most common first event and is associated with basal-like subtype, whereas in the majority of luminal tumors, mutation of TP53 occurs first and mutant PIK3CA is rarely detected. We also observed intratumor heterogeneity for the loss of wild-type BRCA1 and increased cell proliferation and centrosome amplification in the normal breast epithelium of BRCA1 mutation carriers. Our results have important implications for the design of chemopreventive and therapeutic interventions in this high-risk patient population.

The JAK2/STAT3 signaling pathway is required for growth of CD44⁺CD24⁻ stem cell-like breast cancer cells in human tumors

Intratumor heterogeneity is a major clinical problem because tumor cell subtypes display variable sensitivity to therapeutics and may play different roles in progression. We previously characterized 2 cell populations in human breast tumors with distinct properties: CD44+CD24- cells that have stem cell-like characteristics, and CD44-CD24+ cells that resemble more differentiated breast cancer cells. Here we identified 15 genes required for cell growth or proliferation in CD44+CD24- human breast cancer cells in a large-scale loss-of-function screen and found that inhibition of several of these (IL6, PTGIS, HAS1, CXCL3, and PFKFB3) reduced Stat3 activation. We found that the IL-6/JAK2/Stat3 pathway was preferentially active in CD44+CD24- breast cancer cells compared with other tumor cell types, and inhibition of JAK2 decreased their number and blocked growth of xenografts. Our results highlight the differences between distinct breast cancer cell types and identify targets such as JAK2 and Stat3 that may lead to more specific and effective breast cancer therapies.

Characterization of human pancreatic orthotopic tumor xenografts suitable for drug screening

BACKGROUND

Efforts to identify novel therapeutic options for human pancreatic ductal adenocarcinoma (PDAC) have failed to result in a clear improvement in patient survival to date. Pancreatic cancer requires efficient therapies that must be designed and assayed in preclinical models with improved predictor ability. Among the available preclinical models, the orthotopic approach fits with this expectation, but its use is still occasional.

METHODS

An in vivo platform of 11 orthotopic tumor xenografts has been generated by direct implantation of fresh surgical material. In addition, a frozen tumorgraft bank has been created, ensuring future model recovery and tumor tissue availability.

RESULTS

Tissue microarray studies allow showing a high degree of original histology preservation and maintenance of protein expression patterns through passages. The models display stable growth kinetics and characteristic metastatic behavior. Moreover, the molecular diversity may facilitate the identification of tumor subtypes and comparison of drug responses that complement or confirm information obtained with other preclinical models.

CONCLUSIONS

This panel represents a useful preclinical tool for testing new agents and treatment protocols and for further exploration of the biological basis of drug responses.

The neuronal influence on tumor progression

Nerve fibers accompany blood and lymphatic vessels all over the body. An extensive amount of knowledge has been obtained with regard to tumor angiogenesis and tumor lymphangiogenesis, yet little is known about the potential biological effects of "neoneurogenesis". Cancer cells can exploit the advantage of the factors released by the nerve fibers to generate a positive microenvironment for cell survival and proliferation. At the same time, they can stimulate the formation of neurites by secreting neurotrophic factors and axon guidance molecules. The neuronal influence on the biology of a neoplasm was initially described several decades ago. Since then, an increasing amount of experimental evidence strongly suggests the existence of reciprocal interactions between cancer cells and nerves in humans. Moreover, researchers have been able to demonstrate a crosstalk between cancer cells and nerve fibers as a strategy for survival. Despite all these evidence, a lot remains to be done in order to clarify the role of neurotransmitters, neuropeptides, and their associated receptor-initiated signaling pathways in the development and progression of cancer, and response to therapy. A global-wide characterization of the neurotransmitters or neuropeptides present in the tumor microenvironment would provide insights into the real biological influences of the neuronal tissue on tumor progression. This review is intended to discuss our current understanding of neurosignaling in cancer and its potential implications on cancer prevention and therapy. The review will focus on the soluble factors released by cancer cells and nerve endings, their biological effects and their potential relevance in the treatment of cancer.

Tyrosine kinase receptor transactivation associated to G protein-coupled receptors

G protein-coupled receptors (GPCRs) comprise a large family of membrane receptors involved in signal transduction. These receptors are linked to a variety of physiological and biological processes such as regulation of neurotransmission, growth, cell differentiation and oncogenesis among others. Some of the effects of GPCRs are known to be mediated by the activation of MAPK pathways. Several GPCRs are also able to transactivate receptors with tyrosine kinase activity (TKR) such as EGFR and HER2 and thus to control DNA synthesis and cell proliferation. The interaction between these receptors not only plays an important physiological role but its disregulation can induce pathological states such as cancer. For this reason, the crosstalk between these two types of receptors can be considered a possible mechanism for cell transformation, tumor progression, reactivation of the metastatic disease, and the acquisition of resistance to therapies targeting TKR receptors. The transactivation of some TKRs by GPCRs is related to the lost of response of TKRs to inhibitors of TK activity, mainly by the activation of the c-Src protein which can directly phosphorylate and activate the cytoplasmic domain of a TKR. For these reason, the dual inhibition of GPCRs and TKRs in some types of cancer has been proposed as a better strategy to kill tumor cells. Increased understanding of the mechanisms that interconnect the two pathways regulated by GPCRs and TKRs may facilitate the design of new therapeutic strategies.

Tumor promoting effects of CD95 signaling in chemoresistant cells

Background

CD95 is a death receptor controlling not only apoptotic pathways but also activating mechanisms promoting tumor growth. During the acquisition of chemoresistance to oxaliplatin there is a progressive loss of CD95 expression in colon cancer cells and a decreased ability of this receptor to induce cell death. The aim of this study was to characterize some key cellular responses controlled by CD95 signaling in oxaliplatin-resistant colon cancer cells.

Results

We show that CD95 triggering results in an increased metastatic ability in resistant cells. Moreover, oxaliplatin treatment itself stimulates cell migration and decreases cell adhesion through CD95 activation, since CD95 expression inhibition by siRNA blocks the promigratory effects of oxaliplatin. These promigratory effects are related to the epithelia-to-mesenchymal transition (EMT) phenomenon, as evidenced by the up-regulation of some transcription factors and mesenchymal markers both in vitro and in vivo.

Conclusions

We conclude that oxaliplatin treatment in cells that have acquired resistance to oxaliplatin-induced apoptosis results in tumor-promoting effects through the activation of CD95 signaling and by inducing EMT, all these events jointly contributing to a metastatic phenotype.

Interleukin-15 increases calcineurin expression in 3T3-L1 cells: possible involvement on in vivo adipocyte differentiation

Different studies have revealed that the Ca2+-dependent serine/threonine phosphatase calcineurin is involved in the regulation of adipocyte differentiation. Calcineurin acts as a Ca2+-dependent molecular switch that negatively regulates the ability of 3T3-L1 cells to undergo adipocyte differentiation by preventing the expression of critical proadipogenic transcription factors. In this study we investigated the role of interleukin-15 (IL-15), a cytokine previously known to be involved in the control of fat accretion by adipose cells, in the differentiation of the 3T3-L1 preadipose cell line. We found that IL-15 is able to increase alpha-calcineurin mRNA content in white adipose tissue of rats chronically treated with the cytokine and also in the 3T3-L1 preadipose cell line. Moreover, IL-15 promoted a decrease in both leptin mRNA expression and lipid accumulation, as estimated by Red Oil O staining. Cotreatment with IL-15 and FK506 (a calcineurin inhibitor) resulted in no changes in lipid content compared with the non-treated group. These data suggest that IL-15 directly inhibits adipogenesis, possibly by upregulating alpha-calcineurin and preventing the induction of adipocyte differentiation.

The role of MMP7 and its cross-talk with the FAS/FASL system during the acquisition of chemoresistance to oxaliplatin

Background

The efficacy of oxaliplatin in cancer chemotherapy is limited by the development of drug resistance. MMP7 has been related to the loss of tumor cell response to cytotoxic agents although the exact mechanism is not fully understood. Moreover, MMP7 is an independent prognosis factor for survival in patients with colorectal cancer. The aim of the present study was to analyze the role of MMP7 and its cross-talk with the Fas/FasL system during the acquisition of oxaliplatin resistance in colon cancer cells.

Principal Findings

For this purpose we have developed three different oxaliplatin-resistant cell lines (RHT29, RHCT116 p53^+/+, RHCT116 p53^−/−) from the parental HT29, HCT116 p53^+/+ and HCT116 p53^−/− colon cancer cells. MMP7 basal expression was higher in the resistant compared to the parental cell lines. MMP7 was also upregulated by oxaliplatin in both HT29 (p53 mutant) and RHCT116 p53^−/− but not in the RHCT116 p53^+/+. Inhibition of MMP by 1,10-phenantroline monohydrate or siRNA of MMP7 restores cell sensitivity to oxaliplatin-induced apoptosis in both HT29 and RHCT116 p53^−/− but not in the RHCT116 p53^+/+. Some of these effects are caused by alterations in Fas receptor. Fas is upregulated by oxaliplatin in colon cancer cells, however the RHT29 cells treated with oxaliplatin showed a 3.8-fold lower Fas expression at the cell surface than the HT29 cells. Decrease of Fas at the plasma membrane seems to be caused by MMP7 since its inhibition restores Fas levels. Moreover, functional analysis of Fas demonstrates that this receptor was less potent in inducing apoptosis in RHT29 cells and that its activation induces MAPK signaling in resistant cells.

Conclusions

Taking together, these results suggest that MMP7 is related to the acquisition of oxaliplatin-resistance and that its inhibition restores drug sensitivity by increasing Fas receptor. Furthermore, Fas undergoes a change in its functionality in oxaliplatin-resistant cells inducing survival pathways instead of apoptotic signals.

Effects of IL-15 on rat brown adipose tissue: uncoupling proteins and PPARs

OBJECTIVES

Interleukin-15 (IL-15) plays an important role in lipid metabolism as its administration to rats causes a marked depletion of white adipose tissue (WAT). This reduction in fat mass seems to be caused by and related to hipotriglyceridemia as a result of a lower hepatic lipogenesis and an increased fatty acid oxidation. We have previously observed that IL-15 treatment induces the expression of uncoupling proteins (UCPs) in muscle. The aim of this study was to investigate the effects of IL-15 on brown adipose tissue (BAT), and in particular on genes related to lipid metabolism in this tissue.

METHODS AND PROCEDURES

Male Wistar rats were treated daily with IL-15 for 7 days. Adipose tissues were collected and the mRNA content of UCPs, peroxisome proliferator-activated receptors (PPARs) and several genes implicated in fatty acid transport and oxidation were evaluated on BAT.

RESULTS

IL-15 treatment in rats causes a decrease in the mass of both WAT and BAT (35 and 24%, respectively). In BAT, an important upregulation of the mRNA content of thermogenic proteins (UCP1 and UCP3), lipid-related transcription factors (PPARdelta and PPARalpha) and other proteins implicated in membrane transport (fatty acid translocase (FAT) and fatty acid transport protein (FATP)), mitochondrial transport (carnitine palmitoyl transferase-I (CPT-I) and CPT-II) and consumption (acyl-CoA synthetase 4 (ACS4)) of fatty acids was observed as a consequence of the treatment.

DISCUSSION

The changes observed in BAT suggest that IL-15 could be implicated in lipid consumption in this tissue by regulating lipid oxidation and probably thermogenesis, processes mediated by UCPs and PPARs.

Antiproteolytic effects of plasma from hibernating bears: A new approach for muscle wasting therapy?

BACKGROUND & AIMS

In rodents and humans, inactivity or starvation leads to atrophy of skeletal muscle including a decrease in the number and size of muscle cells and in the myofibrillar protein content. It has previously been described that in overwintering bears the inactivity does not provoke any loss of skeletal muscle cell number or size. Taking all these into account, the aim of this study is to test if hibernating bear plasma has any antiproteolytic effect on incubated rat skeletal muscle.

METHODS

Rat skeletal extensor digitorum longus (EDL) muscles were incubated in the presence of hibernating, non-hibernating and control bear plasma. After that, proteolytic rate was evaluated as levels of tyrosine released to the medium and muscle mRNA content for different proteolytic systems were measured by Northern blot.

RESULTS

Rat skeletal EDL muscles incubation in the presence of hibernating bear plasma resulted in a 40% decrease of the net proteolytic rate. This inhibition of proteolysis was accompanied by decreases in the expression of both lysosomal (cathepsin B) and ubiquitin-dependent (ubiquitin) proteolytic systems.

CONCLUSIONS

The results suggest that during hibernation the bear is able to produce a powerful proteolytic inhibitor which is released to the circulation and blocks muscle wasting associated with immobilization.

Are Peroxisome Proliferator-Activated Receptors Involved in Skeletal Muscle Wasting during Experimental Cancer Cachexia? Role of β2-Adrenergic Agonists

Implantation of the Yoshida AH-130 ascites hepatoma to rats resulted in a decrease in muscle weight 7 days after the inoculation of the tumor. These changes were associated with increases in the mRNA content for both peroxisome proliferator-activated receptor (PPAR) gamma and PPAR delta in skeletal muscle. The increase in gene expression for these transcription factors was related to increases in the expression of several genes involved in fatty acid transport, activation, and oxidation. Tumor burden also resulted in increases in PPAR gamma coactivator-1 alpha gene expression and pyruvate dehydrogenase kinase 4. All these changes in lipid metabolism genes suggest that a metabolic shift occurs in skeletal muscle of tumor-bearing rats toward a more oxidative phenotype. Formoterol treatment to tumor-bearing rats resulted in an amelioration of all the changes observed as a result of tumor burden. Administration of this beta(2)-adrenergic agonist also resulted in a decrease in mRNA content of muscle PPAR alpha, PPAR delta, and PPAR gamma, as well as in mRNA levels of many of the genes involved in both lipid and mitochondrial metabolism. All these results suggest an involvement of the different PPARs as transcription factors related with muscle wasting and also indicate that a possible mode of action of the anticachectic compound formoterol may involve a normalization of the levels of these transcription factors.

Optimized preclinical models for human pancreatic adenocarcinoma therapy research

15019

Background: Efforts to find new therapies for human pancreatic ductal adenocarcinoma (PDAC) have not resulted in clear improvements on patient survival. Better knowledge of resistance mechanisms and redefiniton of molecular targets is essential to design more efficient therapies. The multifactorial origin of PDAC points to combined strategies as the therapy of choice, though the effective development of such strategies is hampered by the lack of optimal preclinical models. We have generated and validated optimized human PDAC models by direct implantation of fresh tumoral tissue into the pancreas of athymic mice. Methods: Thirteen pancreatic adenocarcinoma specimens from PDAC patients were obtained by surgical resection. From each specimen, several 10 mg-fragments were used to generate the corresponding intrapancreatic xenografted tumours. Eleven human PDAC orthotopic models have been successfully generated and perpetuated by succesive passages (up to 4). Histological and molecular analyses of both primary and xenografted tumors have been performed by tissue- array, western-blot and DNA sequentiation. Results: Initial engraftment rate ranged from 20 to 100% (mean 59%) and it improved with succesive passages (mean 76% at second and 90% at third generation). Ki67 expression and degree of differentiation in primary tumors correlated with xenograft growth kinetics. Furthermore, their spontaneous metastatic behaviour fairly reproduced the original patient dissemination patterns. Xenografted tumors kept the original architecture and expression patterns of common PDAC markers. Efficacy of several agents was tested on different xenografted tumors, validating this model and underlining its utility to define future therapeutic strategies for drug development and clinical trials. Conclusions: The orthotopic models described here are, probably, the closest resemblance to a patient clinical setting since they preserve human pancreatic structures, genotypic features and biological behaviour. From their use, biological relevant data could be drawn for future clinical trials and for testing new agents and new drug combinations since they represent, very likely, the most reliable animal models at present.

No significant financial relationships to disclose.

Targets in clinical oncology: the metabolic environment of the patient

Cancer cachexia is a syndrome characterized by a marked weight loss, anorexia, asthenia and anemia. The degree of cachexia is inversely correlated with the survival time of the patient and it always implies a poor prognosis. Lean body mass depletion is one of the main features of cachexia and it involves not only skeletal muscle but also affects cardiac protein. The cachectic state is invariably associated with the presence and growth of the tumour and leads to a malnutrition status due to the induction of anorexia or decreased food intake. In addition, the competition for nutrients between the tumour and the host leads to an accelerated starvation state which promotes severe metabolic disturbances in the host, including hypermetabolism which leads to an increased energetic inefficiency. Unfortunately, at the clinical level, cachexia is not treated until the patient suffers from a considerable weight loss and wasting. Therefore, it is of great interest to analyze possible early markers of the syndrome. In the present review both metabolic and hormonal markers are described. Although the search for the cachectic factor(s) started a long time ago, and although many scientific and economic efforts have been devoted to its discovery, we are still a long way from fully understanding the underlying basis for this syndrome. The suggested mediators (associated with both depletion of fat stores and muscular tissue) can be divided into two categories: of tumour origin (produced and released by the neoplasm) and humoural factors (mainly cytokines). One of the aims of the present review is to summarize and evaluate the different catabolic mediators (both humoural and tumoural) involved in cancer cachexia, since they may represent targets for clinical investigations. Additionally, an overview of the main therapeutic approaches for the treatment of the cachectic syndrome is presented.

The AP-1/NF-kappaB double inhibitor SP100030 can revert muscle wasting during experimental cancer cachexia

Daily treatment of rats bearing the cachectic Yoshida AH-130 ascites hepatoma with the double inhibitor of NF-kappaB and AP-1 SP100030 at a dose of 1 mg/kg of body weight resulted in a clear amelioration of the cachectic effect, especially at the level of skeletal muscle. Thus, tumour-bearing rats treated with SP100030 showed a significant recovery in the weights of gastrocnemius, EDL, tibialis and cardiac muscles. In addition, treatment with the inhibitor affected both liver and kidney weights. The amelioration in muscle weight was accompanied by an increase in MyoD gene expression, the main transcription factor of muscle tissue involved in muscle differentiation, in gastrocnemius muscle. At the dose used in this study, SP100030 was an effective inhibitor of AP-1; however, the NF-kappaB transcription factor was not affected. The effects of the inhibitor seem to be at the level of proteolysis since lower total proteolytic rates were found when incubating isolated rat muscles in the presence of SP100030. The inhibitor influenced the gene expression of the ubiquitin-conjugating enzyme E214K in skeletal muscle of tumour-bearing rats; this enzyme seems to be the main regulator of the activity of the main proteolytic system involved during cancer cachexia, the ubiquitin-proteasome system. In conclusion, treatment of cachectic tumour-bearing rats with SP100030 results in an amelioration of the muscle wasting effect, suggesting that the AP-1 signaling cascade plays an important role in the signaling of muscle wasting associated with disease.