Autophagy Enhances Longevity of Induced Pluripotent Stem Cell-Derived Endothelium via mTOR-Independent ULK1 Kinase

Stem cells are enabling an improved understanding of the peripheral arterial disease, and patient-specific stem cell-derived endothelial cells (ECs) present major advantages as a therapeutic modality. However, applications of patient-specific induced pluripotent stem cell (iPSC)-derived ECs are limited by rapid loss of mature cellular function in culture. We hypothesized that changes in autophagy impact the phenotype and cellular proliferation of iPSC-ECs. Endothelial cells were differentiated from distinct induced pluripotent stem cell lines in 2D culture and purified for CD144 positive cells. Autophagy, mitochondrial morphology, and proliferation were characterized during differentiation and over serial passages in culture. We found that autophagy activity was stimulated during differentiation but stagnated in mature iPSC-ECs. Mitochondria remodeled through mitophagy during differentiation and demonstrated increasing membrane potential and mass through serial passages; however, these plateaued, coinciding with decreased proliferation. To evaluate for oxidative damage, iPSC-ECs were alternatively grown under hypoxic culture conditions; however, hypoxia only transiently improved the proliferation. Stimulating mTOR-independent ULK1-mediated autophagy with a plant derivative AMP kinase activator Rg2 significantly improved proliferative capacity of iPSC-ECs over multiple passages. Therefore, autophagy, a known mediator of longevity, played an active role in remodeling mitochondria during maturation from pluripotency to a terminally differentiated state. Autophagy failed to compensate for increasing mitochondrial mass over serial passages, which correlated with loss of proliferation in iPSC-ECs. Stimulating ULK1-kinase-driven autophagy conferred improved proliferation and longevity over multiple passages in culture. This represents a novel approach to overcoming a major barrier limiting the use of iPSC-ECs for clinical and research applications.

An efficient method to generate kidney organoids at the air-liquid interface

The prevalence of kidney dysfunction continues to increase worldwide, driving the need to develop transplantable renal tissues. The kidney develops from four major renal progenitor populations: nephron epithelial, ureteric epithelial, interstitial and endothelial progenitors. Methods have been developed to generate kidney organoids but few or dispersed tubular clusters within the organoids hamper its use in regenerative applications. Here, we describe a detailed protocol of asynchronous mixing of kidney progenitors using organotypic culture conditions to generate kidney organoids tightly packed with tubular clusters and major renal structures including endothelial network and functional proximal tubules. This protocol provides guidance in the culture of human embryonic stem cells from a National Institute of Health-approved line and their directed differentiation into kidney organoids. Our 18-day protocol provides a rapid method to generate kidney organoids that facilitate the study of different nephrological events including in vitro tissue development, disease modeling and chemical screening. However, further studies are required to optimize the protocol to generate additional renal-specific cell types, interconnected nephron segments and physiologically functional renal tissues.

Taking the Next Step: a Neural Coaptation Orthotopic Hind Limb Transplant Model to Maximize Functional Recovery in Rat

Limb transplant in particular and vascularized composite allotransplant (VCA) in general have wide therapeutic promise that have been stymied by current limitations in immunosuppression and functional neuromotor recovery. Many animal models have been developed for studying unique features of VCA, but here we present a robust reproducible model of orthotopic hind limb transplant in rats designed to simultaneously investigate both aspects of current VCA limitation: immunosuppression strategies and functional neuromotor recovery. At the core of the model rests a commitment to meticulous, time-tested microsurgical techniques such as hand sewn vascular anastomoses and hand sewn neural coaptation of the femoral nerve and the sciatic nerve. This approach yields durable limb reconstructions that allow for longer lived animals capable of rehabilitation, resumption of daily activities, and functional testing. With short-term treatment of conventional immunosuppressive agents, allotransplanted animals survived up to 70 days post-transplant, and isotransplanted animals provide long lived controls beyond 200 days post-operatively. Evidence of neurologic functional recovery is present by 30 days post operatively. This model not only provides a useful platform for interrogating immunological questions unique to VCA and nerve regeneration, but also allows for in vivo testing of new therapeutic strategies specifically tailored for VCA.

A novel and cost-effective ex vivo orthotopic model for the study of human breast cancer in mouse mammary gland organ culture

Mouse mammary organ culture (MMOC) is used to evaluate the efficacy of chemopreventive agents against the development of carcinogen-induced preneoplastic lesions and is highly correlative to in vivo carcinogenesis models. Here, we developed a new ex vivo MMOC model, by introducing human breast cancer cells into the mouse mammary gland. This novel model, termed human breast cancer in MMOC (BCa-MMOC), mimics in vivo orthotopic breast cancer mouse models. To develop this model, estradiol- and progesterone-sensitized female mice were injected with letrozole-sensitive and -resistant T47D breast cancer cells in the mammary glands and then euthanized. The glands were cultured in vitro with hormone-supplemented media. On day 25, the glands were fixed and processed by histopathology and immunohistochemistry to evaluate for the presence of T47D cells, growth pattern, cancer markers and estradiol responsiveness. Histopathological analyses demonstrated an identical pattern of growth between the breast cancer cells injected ex vivo and in vivo Interestingly, clusters of cancer cells in the mammary gland stroma appeared similar to those observed in human breast tumors. The injected T47D cells survived and proliferated for 15 days maintaining expression of estrogen receptor alpha (ER), progesterone receptor (PR), epidermal growth factor receptor (EGFR), and aromatase. The aromatase-overexpressing T47D grown in the BCa-MMOC sufficiently metabolized estrogen, resulting in enhanced cell proliferation, induction of estrogen target genes (i.e. ER and PR-B), and showed typical changes to estrogenic milieu. In summary, here we show a novel, inexpensive ex vivo model, to potentially study the effects of therapeutic agents on cancer cells grown in an orthotopic micromilieu.This article has an associated First Person interview with the first author of the paper.

Expression of miR-18a and miR-210 in Normal Breast Tissue as Candidate Biomarkers of Breast Cancer Risk

miRNAs are noncoding RNAs with abnormal expression in breast cancer; their expression in high-risk benign breast tissue may relate to breast cancer risk. We examined miRNA profiles in contralateral unaffected breasts (CUB) of patients with breast cancer and validated resulting candidates in two additional sample sets. Expression profiles of 754 mature miRNAs were examined using TaqMan Low Density Arrays in 30 breast cancer samples [15 estrogen receptor (ER)-positive and 15 ER-negative] and paired CUBs and 15 reduction mammoplasty controls. Pairwise comparisons identified miRNAs with significantly differential expression. Seven candidate miRNAs were examined using qRT-PCR in a second CUB sample set (40 cases, 20 ER+, 20 ER-) and 20 reduction mammoplasty controls. Further validation was performed in 80 benign breast biopsy (BBB) samples; 40 from cases who subsequently developed breast cancer and 40 from controls who did not. Logistic regression, using tertiles of miRNA expression, was used to discriminate cases from controls. Seven miRNAs were differentially expressed in tumors and CUBs versus reduction mammoplasty samples. Among them, miR-18a and miR-210 were validated in the second CUB set, showing significantly higher expression in tumor and CUBs than in reduction mammoplasty controls. The expression of miR-18a and miR-210 was also significantly higher in BBB cases than in BBB controls. When both miR-18a and miR-210 were expressed in the upper tertiles in BBB, OR for subsequent cancer was 3.20, P = 0.023. miR-18a and miR-210 are expressed at higher levels in CUBs of patients with breast cancer, and in BBB prior to cancer development, and are therefore candidate breast cancer risk biomarkers. Cancer Prev Res; 10(1); 89-97. ©2016 AACR.

Progesterone receptor blockade in human breast cancer cells decreases cell cycle progression through G2/M by repressing G2/M genes

Background

The synthesis of specific, potent progesterone antagonists adds potential agents to the breast cancer prevention and treatment armamentarium. The identification of individuals who will benefit from these agents will be a critical factor for their clinical success.

Methods

We utilized telapristone acetate (TPA; CDB-4124) to understand the effects of progesterone receptor (PR) blockade on proliferation, apoptosis, promoter binding, cell cycle progression, and gene expression. We then identified a set of genes that overlap with human breast luteal-phase expressed genes and signify progesterone activity in both normal breast cells and breast cancer cell lines.

Results

TPA administration to T47D cells results in a 30 % decrease in cell number at 24 h, which is maintained over 72 h only in the presence of estradiol. Blockade of progesterone signaling by TPA for 24 h results in fewer cells in G2/M, attributable to decreased expression of genes that facilitate the G2/M transition. Gene expression data suggest that TPA affects several mechanisms that progesterone utilizes to control gene expression, including specific post-translational modifications, and nucleosomal organization and higher order chromatin structure, which regulate access of PR to its DNA binding sites.

Conclusions

By comparing genes induced by the progestin R5020 in T47D cells with those increased in the luteal-phase normal breast, we have identified a set of genes that predict functional progesterone signaling in tissue. These data will facilitate an understanding of the ways in which drugs such as TPA may be utilized for the prevention, and possibly the therapy, of human breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2355-5) contains supplementary material, which is available to authorized users.

Abstract P3-04-10: Progesterone receptor (PR) blockade by antiprogestin, CDB4124 in hormone receptor positive breast cancer cells leads to significant inhibition of G2/M cell cycle genes

Background: Several lines of evidence suggest that progesterone signaling is important in the breast cancer development, particularly in young women. Therefore, we sought to establish the effects of the antiprogestin CDB4124 (telapristone), and to identify PR related signature genes in hormone receptor positive (ER+ PR+) breast cancer cells.

Methods: The PR expressing breast cancer cell line T47D was used to evaluate responses to PR ligands (P4, MPA and R5020, 10nM) alone or in combination with estradiol (E2, 1nM). The effects of the antiprogestin CDB4124 (0.1 or 1μM) were tested using varying hormonal conditions. The effect on (a) PRE promoter activity by dual luciferase assay; (b) cell proliferation using the MTT assay; (c) cell cycle by flow cytometry; (d) determination of gene expression signatures related to active PR responses. For the gene array experiment, cells were treated with either vehicle or R5020 (10nM) or R5020 (10nM) plus CDB4124 (1μM) in triplicate for 24hr. Total RNA was isolated and converted to cDNA and human Illumina chip microarray was performed. Data obtained from the microarray was further analyzed by Metacore Gene GO and Ingenuity Pathway Analysis. Real time PCR was performed in triplicate to confirm the expression of those genes related to the cell cycle and proliferation. ANOVA analysis and post-hoc Sidak test were used to determined the statistical significance of the data.

Results: The PRE reporter activity resulting from P4, MPA and R5020 stimulation was inhibited by 80-90% in the presence of CDB4124 at 10 to 1000nM (p< 0.001). Cell proliferation was increased by PR ligands (P4, MPA and R5020) in the presence of E2; the addition of CDB4124 caused 50% inhibition of proliferation (p< 0.01) at 72 hours. Cell cycle analysis of T47D cells treated with P4, MPA and R5020 alone or in combination with E2 showed significant increases in S and G2/M phase and decreases in G0/G1. These were blocked by CDB4124 at 0.1 or 1.0μM (p<0.05 for all). Gene GO metacore analysis of genes identified in the microarray revealed significant enrichment of cell cycle pathways (FDR, p< 1.0X10-11 ) upon treatment with R5020. The addition of CDB4124 to R5020 treated samples showed inhibition of the same cell cycle pathways (FDR,p<1.0X10-14). A 16-gene panel related to G2/M phase of cell cycle was selected based on >1.5 fold upregulation (p<0.001) during treatment with R5020,10nM and blockade by CD4124. Real time PCR confirmed upregulation of this 16 gene panel ≥2.0 (p<0.05) in the presence of PR ligands alone or in combination with E2 which were significantly blocked by the addition of CDB4124.

Conclusion: These data demonstrate that PR mediated cell proliferation occurs upon treatment with three different ligands of PR (P4, MPA and R5020); that PR actively engages key genes involved in the G2/M phase of the cell cycle to drive proliferation of ER+ and PR+ cells; and that the antiprogestin, CBD4124 is a potent transcriptional inhibitor for blockade of PR mediated cell proliferation in hormone receptor positive breast cancer cells.

Citation Format: Akash Gupa, Mi Ran Choi, Susan E Clare, Jun Wang, Oukseub Lee, David Z Ivancic, J Julie Kim, Seema A Khan. Progesterone receptor (PR) blockade by antiprogestin, CDB4124 in hormone receptor positive breast cancer cells leads to significant inhibition of G2/M cell cycle genes [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-04-10.

Abstract 168: Differential microRNA expression profiles of breast cancer and matched benign breast samples stratified by ER status

Background: The identification of women at high risk for breast cancer remains a challenge. Robust risk markers that better stratify women for their probability of developing breast cancer would represent a significant advance for breast cancer prevention research. microRNAs (miRNAs) are a large group of non-coding RNAs, generally 18-25 nt long, which block messenger RNA (mRNA) translation and affect mRNA stability. Since the molecular signature of ER-positive breast cancer differs from that of ER-negative breast cancer, we hypothesized that miRNA profile differences may be reflected in the contralateral normal breast tissue of women with breast cancer.Methods:we used a well-annotated set of samples comprised of matched contra-lateral benign breast tissue (MCBB) from 30 women (15 ER positive and 15 ER negative tumor with their corresponding MCBBs matched for age and race) to generate expression profiles of 754 mature miRNAs by TaqMan Low Density Arrays (TLDAs). Following background subtraction, miRNA levels were normalized against controls and compared across groups using tests of contrast on estimated parameters from a full ANOVA model with Empirical Bayes variance correction and False Discovery Rate (FDR) control at p≪0.05 using the Benjamini-Hochberg method. Following this strategy, we have performed different pair-wise comparisons as follows: 1) ER+ to ER- tumors, 2) ER+ tumor to MCBB tissue, 3) ER- tumor to MCBB, and 4) MCBB tissue from women with ER+ versus ER- tumors.Results: We observe clear patterns of differential expression between ER+ and ER- tumors. Four miRNAs were significantly down-regulated in ER+ tumors compared to ER-negative, whereas miR190b was significantly up-regulated in ER- lesions. More striking were the patterns of differential expression of 23 miRNAs in ER- breast cancer tissue compared to MCCB. A similar analysis in ER+ breast cancer and MCBB yeilded at least 29 miRNAs with significantly differential expression. Among these differentially expressed miRNAs, nine miRNAs were common in the ER- and ER+ cancers, and the remainder were distinct. Notably, we found that miR-18a and miR-18b expression were more than 50-fold higher in ER- cancer samples compared to MCBB, but when we compared ER+ tumor to MCBB, we found no significant difference in miR-18b expression. On the other hand, miR-96 and miR-183 are over-expressed in both ER+ and ER- tumors when compared to the MCBB set. Comparing MCBB from women with ER-and ER+ breast cancer yielded no significant differences. Conclusion: we see striking differences in the patterns of miRNA expression differences between breast cancer samples and matched contralateral benign tissue when stratified by ER status.The majority of the miRNAs identified in our analyses are novel. These findings have significant potential for the identification of new ER- status specific and biologically significant molecular biomarkers.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 168. doi:10.1158/1538-7445.AM2011-168