Manjushree Anjanappa

Cancer Affects microRNA Expression, Release, and Function in Cardiac and Skeletal Muscle

Circulating microRNAs (miRNA) are emerging as important biomarkers of various diseases, including cancer. Intriguingly, circulating levels of several miRNAs are lower in patients with cancer compared with healthy individuals. In this study, we tested the hypothesis that a circulating miRNA might serve as a surrogate of the effects of cancer on miRNA expression or release in distant organs. Here we report that circulating levels of the muscle-enriched miR486 is lower in patients with breast cancer compared with healthy individuals and that this difference is replicated faithfully in MMTV-PyMT and MMTV-Her2 transgenic mouse models of breast cancer. In tumor-bearing mice, levels of miR486 were relatively reduced in muscle, where there was elevated expression of the miR486 target genes PTEN and FOXO1A and dampened signaling through the PI3K/AKT pathway. Skeletal muscle expressed lower levels of the transcription factor MyoD, which controls miR486 expression. Conditioned media (CM) obtained from MMTV-PyMT and MMTV-Her2/Neu tumor cells cultured in vitro were sufficient to elicit reduced levels of miR486 and increased PTEN and FOXO1A expression in C2C12 murine myoblasts. Cytokine analysis implicated tumor necrosis factor α (TNFα) and four additional cytokines as mediators of miR486 expression in CM-treated cells. Because miR486 is a potent modulator of PI3K/AKT signaling and the muscle-enriched transcription factor network in cardiac/skeletal muscle, our findings implicated TNFα-dependent miRNA circuitry in muscle differentiation and survival pathways in cancer.

Ethnicity-Dependent and -Independent Heterogeneity in Healthy Normal Breast Hierarchy Impacts Tumor Characterization

Recent reports of widespread genetic variation affecting regulation of gene expression raise the possibility of significant inter-individual differences in stem-progenitor-mature cell hierarchy in adult organs. This has not been explored because of paucity of methods to quantitatively assess subpopulation of normal epithelial cells on individual basis. We report the remarkable inter-individual differences in differentiation capabilities as documented by phenotypic heterogeneity in stem-progenitor-mature cell hierarchy of the normal breast. Ethnicity and genetic predisposition are partly responsible for this heterogeneity, evidenced by the finding that CD44+/CD24- and PROCR+/EpCAM- multi-potent stem cells were elevated significantly in African American women compared with Caucasians. ALDEFLUOR+ luminal stem/progenitor cells were lower in BRCA1-mutation carriers compared with cells from healthy donors (p = 0.0014). Moreover, tumor and adjoining-normal breast cells of the same patients showed distinct CD49f+/EpCAM+ progenitor, CD271+/EpCAM- basal, and ALDEFLUOR+ cell profiles. These inter-individual differences in the rate of differentiation in the normal breast may contribute to a substantial proportion of transcriptome, epigenome, and signaling pathway alterations and consequently has the potential to spuriously magnify the extent of documented tumor-specific gene expression. Therefore, comparative analysis of phenotypically defined subpopulations of normal and tumor cells on an individual basis may be required to identify cancer-specific aberrations.

Individualized breast cancer characterization through single-cell analysis of tumor and adjacent normal cells

There is a need to individualize assays for tumor molecular phenotyping, given variations in the differentiation status of tumor and normal tissues in different patients. To address this, we performed single-cell genomics of breast tumors and adjacent normal cells propagated for a short duration under growth conditions that enable epithelial reprogramming. Cells analyzed were either unselected for a specific subpopulation or phenotypically defined as undifferentiated and highly clonogenic ALDH+/CD49f+/EpCAM+ luminal progenitors, which express both basal cell and luminal cell-enriched genes. We analyzed 420 tumor cells and 284 adjacent normal cells for expression of 93 genes that included a PAM50-intrinsic subtype classifier and stemness-related genes. ALDH+/CD49f+/EpCAM+ tumor and normal cells clustered differently compared with unselected tumor and normal cells. PAM50 gene-set analyses of ALDH+/CD49f+/EpCAM+ populations efficiently identified major and minor clones of tumor cells, with the major clone resembling clinical parameters of the tumor. Similarly, a stemness-associated gene set identified clones with divergent stemness pathway activation within the same tumor. This refined expression profiling technique distinguished genes truly deregulated in cancer from genes that identify cellular precursors of tumors. Collectively, the assays presented here enable more precise identification of cancer-deregulated genes, allow for early identification of therapeutically targetable tumor cell subpopulations, and ultimately provide a refinement of precision therapeutics for cancer treatment. Cancer Res; 77(10); 2759-69. ©2017 AACR.

Distinct Effects of Adipose-derived Stem Cells and Adipocytes on Normal and Cancer Cell Hierarchy

Adipose-derived stem cells (ASC) have received considerable attention in oncology because of the known direct link between obesity and cancer as well as the use of ASCs in reconstructive surgery after tumor ablation. Previous studies have documented how cancer cells commandeer ASCs to support their survival by altering extracellular matrix composition and stiffness, migration, and metastasis. This study focused on delineating the effects of ASCs and adipocytes on the self-renewal of stem/progenitor cells and hierarchy of breast epithelial cells. The immortalized breast epithelial cell line MCF10A, ductal carcinoma in situ (DCIS) cell lines MCF10DCIS.com and SUM225, and MCF10A-overexpressing SRC oncogene were examined using a mammosphere assay and flow cytometry for the effects of ASCs on their self-renewal and stem-luminal progenitor-differentiated cell surface marker profiles. Interestingly, ASCs promoted the self-renewal of all cell types except SUM225. ASC coculture or treatment with ASC conditioned media altered the number of CD49fhigh/EpCAMlow basal/stem-like and CD49fmedium/EpCAMmedium luminal progenitor cells. Among multiple factors secreted by ASCs, IFNγ and hepatocyte growth factor (HGF) displayed unique actions on epithelial cell hierarchy. IFNγ increased stem/progenitor-like cells while simultaneously reducing the size of mammospheres, whereas HGF increased the size of mammospheres with an accompanying increase in luminal progenitor cells. ASCs expressed higher levels of HGF, whereas adipocytes expressed higher levels of IFNγ. As luminal progenitor cells are believed to be prone for transformation, IFNγ and HGF expression status of ASCs may influence susceptibility for developing breast cancer as well as on outcomes of autologous fat transplantation on residual/dormant tumor cells. Implications: This study suggests that the ratio of ASCs to adipocytes influences cancer cell hierarchy, which may impact incidence and progression. Mol Cancer Res; 14(7); 660–71. ©2016 AACR.

Abstract 4993: Breast epithelial cell lines from normal breast with luminal and intrinsic subtypes -enriched gene expression document inter-individual differences in differentiation cascade

Breast cancers are classified into five intrinsic subtypes based on gene expression profile. It is suggested that these intrinsic subtypes originate from specific developmental stage of breast epithelial cell hierarchy, stem-progenitor-mature cell. However, normal breast epithelial cell lines representing these intrinsic subtypes are yet to be created. Using normal breast tissues of ancestry-mapped Caucasian, African American, and Hispanic women and a primary cell culturing system that allows growth of normal epithelial cells of different developmental stages including estrogen receptor-positive mature luminal cells, we created 15 human telomerase-immortalized breast epithelial cell lines. These cells formed acini on a matrigel and ductal structures on 3-dimensional collagen or hydrogel, indicating that these cell lines have retained characteristics of normal breast epithelial cells. RNA sequencing and PAM50 intrinsic subtype clustering algorithms were used to identify the intrinsic subtypes of the immortalized cell lines together with two well characterized “normal” breast epithelial cell lines MCF10A and HMEC as well as luminal breast cancer cell line MCF-7. Unlike MCF10A and HMEC, which are enriched for basal-like gene expression pattern, our cell lines classified into luminal A, basal, and normal-like subtypes. This was also reflected in the immunofluorescence staining with basal marker KRT14 and luminal marker KRT19. Few of these cell lines were dual positive for KRT14 and KRT19, but in varying proportions. Cell lines representing claudin-low subtypes were also created, which are phenotypically (CD201+/EpCAM-) different from the above cell lines. Cell lines showed inter-individual differences in stemness/differentiation capabilities and variable basal activity of signaling molecules such as NF-kB, AP-1 and pERK, which is consistent with, possibly reflecting, recent discoveries of genetic variations in gene regulatory regions among general population that contribute to widespread differences in gene expression/signaling under “normal” state. As majority of breast cancers are believed to originate from luminal progenitor cells, which are well represented our cell lines, these cell lines are ideal to delineate the impact of inter-individual and ethnic differences in normal breast biology on breast cancer initiation and progression as well as to determine whether cell-type-origin instead of genomic aberration drives intrinsic subtype-enriched gene expression patterns in breast tumors. Citation Format: Brijesh Kumar, Mayuri Prasad, Manjushree Anjanappa, Poornima Nakshatri, Natascia Marino, Anna Maria Storniolo, Xi Rao, Sheng Liu, Jun Wan, Yunlong Liu, Harikrishna Nakshatri. Breast epithelial cell lines from normal breast with luminal and intrinsic subtypes -enriched gene expression document inter-individual differences in differentiation cascade [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 4993.

Dependence receptor UNC5A restricts luminal to basal breast cancer plasticity and metastasis

BackgroundThe majority of estrogen receptor-positive (ERα+) breast cancers respond to endocrine therapies. However, resistance to endocrine therapies is common in 30% of cases, which may be due to altered ERα signaling and/or enhanced plasticity of cancer cells leading to breast cancer subtype conversion. The mechanisms leading to enhanced plasticity of ERα-positive cancer cells are unknown.MethodsWe used short hairpin (sh)RNA and/or the CRISPR/Cas9 system to knockdown the expression of the dependence receptor UNC5A in ERα+ MCF7 and T-47D cell lines. RNA-seq, quantitative reverse transcription polymerase chain reaction, chromatin immunoprecipitation, and Western blotting were used to measure the effect of UNC5A knockdown on basal and estradiol (E2)-regulated gene expression. Mammosphere assay, flow cytometry, and immunofluorescence were used to determine the role of UNC5A in restricting plasticity. Xenograft models were used to measure the effect of UNC5A knockdown on tumor growth and metastasis. Tissue microarray and immunohistochemistry were utilized to determine the prognostic value of UNC5A in breast cancer. Log-rank test, one-way, and two-way analysis of variance (ANOVA) were used for statistical analyses.ResultsKnockdown of the E2-inducible UNC5A resulted in altered basal gene expression affecting plasma membrane integrity and ERα signaling, as evident from ligand-independent activity of ERα, altered turnover of phosphorylated ERα, unique E2-dependent expression of genes effecting histone demethylase activity, enhanced upregulation of E2-inducible genes such as BCL2, and E2-independent tumorigenesis accompanied by multiorgan metastases. UNC5A depletion led to the appearance of a luminal/basal hybrid phenotype supported by elevated expression of basal/stem cell-enriched ∆Np63, CD44, CD49f, epidermal growth factor receptor (EGFR), and the lymphatic vessel permeability factor NTN4, but lower expression of luminal/alveolar differentiation-associated ELF5 while maintaining functional ERα. In addition, UNC5A-depleted cells acquired bipotent luminal progenitor characteristics based on KRT14+/KRT19+ and CD49f+/EpCAM+ phenotype. Consistent with in vitro results, UNC5A expression negatively correlated with EGFR expression in breast tumors, and lower expression of UNC5A, particularly in ERα+/PR+/HER2− tumors, was associated with poor outcome.ConclusionThese studies reveal an unexpected role of the axon guidance receptor UNC5A in fine-tuning ERα and EGFR signaling and the luminal progenitor status of hormone-sensitive breast cancers. Furthermore, UNC5A knockdown cells provide an ideal model system to investigate metastasis of ERα+ breast cancers.

Pharmacological Dual Inhibition of Tumor and Tumor-Induced Functional Limitations in a Transgenic Model of Breast Cancer

Breast cancer progression is associated with systemic effects, including functional limitations and sarcopenia without the appearance of overt cachexia. Autocrine/paracrine actions of cytokines/chemokines produced by cancer cells mediate cancer progression and functional limitations. The cytokine-inducible transcription factor NF-κB could be central to this process, as it displays oncogenic functions and is integral to the Pax7:MyoD:Pgc-1β:miR-486 myogenesis axis. We tested this possibility using the MMTV-PyMT transgenic mammary tumor model and the NF-κB inhibitor dimethylaminoparthenolide (DMAPT). We observed deteriorating physical and functional conditions in PyMT+ mice with disease progression. Compared with wild-type mice, tumor-bearing PyMT+ mice showed decreased fat mass, impaired rotarod performance, and reduced grip strength as well as increased extracellular matrix (ECM) deposition in muscle. Contrary to acute cachexia models described in the literature, mammary tumor progression was associated with reduction in skeletal muscle stem/satellite-specific transcription factor Pax7. Additionally, we observed tumor-induced reduction in Pgc-1β in muscle, which controls mitochondrial biogenesis. DMAPT treatment starting at 6 to 8 weeks age prior to mammary tumor occurrence delayed mammary tumor onset and tumor growth rates without affecting metastasis. DMAPT overcame cancer-induced functional limitations and improved survival, which was accompanied with restoration of Pax7, Pgc-1β, and mitochondria levels and reduced ECM levels in skeletal muscles. In addition, DMAPT restored circulating levels of 6 out of 13 cancer-associated cytokines/chemokines changes to levels seen in healthy animals. These results reveal a pharmacological approach for overcoming cancer-induced functional limitations, and the above-noted cancer/drug-induced changes in muscle gene expression could be utilized as biomarkers of functional limitations. Mol Cancer Ther; 16(12); 2747–58. ©2017 AACR.

Abstract 1753: Refining breast cancer characterization through single-cell analysis ofex vivoreprogrammed tumor and adjacent normal cells

Discovery of inter-individual functional variations in gene regulatory elements and the observation that tumor and normal tissues of the same organ are in different differentiation states necessitate rethinking of gene expression based subclassification/characterization of tumors. To address this issue, we performed single cell genomics of breast tumors and adjacent-normal cells propagated using epithelial reprogramming growth conditions for a short duration. Epithelial cells analyzed were either unselected for specific subpopulation or phenotypically defined undifferentiated ALDH+/CD49f+/EpCAM+ luminal progenitors present in the normal breast, which express both basal and luminal-enriched genes. Expression of 93 genes that included PAM50 intrinsic subtype classifier and stemness-related genes was analyzed in 420 tumor and 284 adjacent-normal cells. ALDH+/CD49f+/EpCAM+ tumor and normal cells clustered differently compared to unselected tumor and normal cells. PAM50 genes-set analyses of ALDH+/CD49f+/EpCAM+ populations efficiently identified major and minor clones of tumor cells with the major clone resembling clinical parameters of the tumor. Similarly, stemness-associated gene set identified clones with divergent stemness pathway activation within the same patient sample. This refined technique distinguished genes truly deregulated in cancer from genes that identify cellular precursors of tumors. Collectively, assays presented here may enable precise identification of genes deregulated in cancer, early identification of therapeutically-targetable minor population of tumor cells, and eventually to refinement of precision therapeutics. Citation Format: Harikrishna Nakshatri, Manjushree Anjanappa, Angelo Cardoso, Lijun Cheng, Safa Mohamad, Andrea Gunawan, Susan Rice, Yan Dong, Lang Li, Edward Srour. Refining breast cancer characterization through single-cell analysis of ex vivo reprogrammed tumor and adjacent normal cells [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 1753. doi:10.1158/1538-7445.AM2017-1753

Abstract P1-06-05: The impact of ethnicity on normal breast biology

The incidence of/mortality from the most aggressive triple negative breast cancer (TNBC) is higher in African American- (AA) than Caucasian (CA)-women. In contrast, breast cancer in Hispanic-women is generally less aggressive. There is an ongoing debate as to whether AA-women have an increased incidence of TNBCs that have poor outcome or there are unique biological factors in AA-women that promote aggressive biology. Through unique approaches, we provide evidence for distinct biology in the normal breasts of CA-women, AA-women, and Hispanic-women. Using resources from the Komen Normal Tissue Bank and a primary cell culturing system that enabled propagation of normal epithelial cells of different lineages including mature-luminal, luminal-progenitor, and stem cells from different ethnic groups, we have identified a subpopulation of CD44high/CD24- cells that are unique to AA-women (p=0.0001). This AA-women-specific subpopulation expressed higher levels of Collagen 3A1, Collagen 5A2, CTNNB1 (β-Catenin of Wnt), FOXC2, and ZEB1 compared to common CD44+/CD24+ subpopulation in every breast. Gene expression pattern in the AA-specific CD44high/CD24- population showed marked similarity to gene expression pattern in the recently described PROCR+ multi-potent mammary stem cells. Indeed, the breast epithelial cells of AA-women were enriched for PROCR-positive stem cells compared to CA-women or Hispanic-women (p=0.015). In contrast to cells from CA- and AA-women, cells isolated from the healthy breast of Hispanic-women displayed mostly differentiated features as they were enriched for CD49f-/EpCAM+ and CD271-/EpCAM+ mature cells. Cells from CA-women, AA-women and Hispanic-women are currently being immortalized to determine the cell types that are preferentially immortalized in each of these ethnic groups. These results suggest ethnicity-dependent differences in Wnt, extracellular matrix, and epithelial to mesenchymal transition (EMT) signaling in normal breast epithelial cells and differences in the proportion of cells that are susceptible to immortalization/transformation. This work is supported by Susan G. Komen for the Cure to HN (SAC110025). Citation Format: Nakshatri H, Anjanappa M, Bhat-Nakshatri P. The impact of ethnicity on normal breast biology. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-06-05.

Abstract 3652: Identification of cancer-specific signaling networks: what is “normal” control

Success of precision medicine depends on definitive identification of cancer-specific alterations in signaling pathways. However, identifying cancer-specific signaling networks is challenging because of lack of proper control tissue for differential gene expression analyses. Most studies in breast cancer utilize tumor-adjacent normal tissue or reduction mammoplasty samples as “normal” controls. We recently reported that breast epithelial cells from healthy donors as well as tumor-adjacent normal are in different differentiation states compared with tumor cells and the differences in differentiation status alone could account for major transcriptome variations between normal and tumor. To overcome these limitations, we propagated breast epithelial cells from three healthy donors (healthy-normal), two high-risk patients, two tumor-adjacent normal (HR/AD-normal) and five tumor samples of different molecular subtypes. Phenotypically defined (CD49f+/EpCAM+) luminal progenitor cells were sorted from these cultures and subjected to RNA-seq analyses. Pathway analysis revealed activation of cell-intrinsic pro-inflammatory signaling in HR/AD-normal cells compared with healthy-normal cells. This signaling network was further amplified in tumor cells. The pro-inflammatory chemokine CCL2, which is overexpressed in highly aggressive breast cancer, and the cytokine TNFRSF11B were elevated in HR/AD-normal luminal progenitor cells. Despite using phenotypically defined cells in the transcriptome analyses, cancer-specific signaling network identification was directly influenced by the type of controls used; healthy-normal or HR/AD-normal. While cancer-enriched PI3K and NF-κB activation was observed when compared to any kind of control, SRC kinase activation was noted only when cells from healthy-normal were used as a control. In general, the number of tumor signaling networks identified using healthy-normal as a control was higher than when compared with HR/AD-normal as a control. These results suggest that considerable attention should be placed on the type of tissues used as control for definitive identification of cancer-specific signaling networks and therapies to target such pathways. Additionally, these data show that non-cancer tissues of breast cancer patients acquire a cell intrinsic pro-inflammatory phenotype, which may be prerequisite for cancer development and potentially an early-detection tool. Citation Format: Manjushree Anjanappa, Yangyang Hao, Howard J. Edenberg, Yunlong Liu, Harikrishna Nakshatri. Identification of cancer-specific signaling networks: what is “normal” control. [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 3652.