Activation of an Estrogen/ Estrogen Receptor Signaling by BIG3 Through Its Inhibitory Effect on Nuclear Transport of PHB2/REA in Breast Cancer

Breast cancer is known to be a hormone-dependent disease, and estrogens through an interaction with estrogen receptor (ER) enhance the proliferative and metastatic activity of breast tumor cells. Here we show a critical role of transactivation of BIG3, brefeldin A-inhibited guanine nucleotide-exchange protein 3, in activation of the estrogen/ER signaling in breast cancer cells. Knocking-down of BIG3 expression with small-interfering RNA (siRNA) drastically suppressed the growth of breast cancer cells. Subsequent co-immunoprecipitation and immunoblotting assays revealed an interaction of BIG3 with prohibitin 2/repressor of estrogen receptor activity (PHB2/REA). When BIG3 was absent, stimulation of estradiol caused the translocation of PHB2/REA to the nucleus, enhanced the interaction of PHB2/REA and ER[alpha], and resulted in suppression of the ER[alpha]; transcriptional activity. On the other hand, when BIG3 was present, BIG3 trapped PHB2/REA in cytoplasm and inhibited its nuclear translocation, and caused enhancement of ER[alpha]; transcriptional activity. Our results imply that BIG3 overexpression is one of the important mechanisms causing the activation of the estrogen/ER[alpha]; signaling pathway in the hormone-related growth of breast cancer cells

LRH-1 drives colon cancer cell growth by repressing the expression of the <i>CDKN1A</i> gene in a p53-dependent manner

Liver receptor homologue 1 (LRH-1) is an orphan nuclear receptor that has been implicated in the progression of breast, pancreatic and colorectal cancer (CRC). To determine mechanisms underlying growth promotion by LRH-1 in CRC, we undertook global expression profiling following siRNA-mediated LRH-1 knockdown in HCT116 cells, which require LRH-1 for growth and in HT29 cells, in which LRH-1 does not regulate growth. Interestingly, expression of the cell cycle inhibitor p21 (CDKN1A) was regulated by LRH-1 in HCT116 cells. p21 regulation was not observed in HT29 cells, where p53 is mutated. p53 dependence for the regulation of p21 by LRH-1 was confirmed by p53 knockdown with siRNA, while LRH-1-regulation of p21 was not evident in HCT116 cells where p53 had been deleted. We demonstrate that LRH-1-mediated p21 regulation in HCT116 cells does not involve altered p53 protein or phosphorylation, and we show that LRH-1 inhibits p53 recruitment to the p21 promoter, likely through a mechanism involving chromatin remodelling. Our study suggests an important role for LRH-1 in the growth of CRC cells that retain wild-type p53

Involvement of maternal embryonic leucine zipper kinase (MELK) in mammary carcinogenesis through interaction with Bcl-G, a pro-apoptotic member of the Bcl-2 family

INTRODUCTION: Cancer therapies directed at specific molecular targets in signaling pathways of cancer cells, such as tamoxifen, aromatase inhibitors and trastuzumab, have proven useful for treatment of advanced breast cancers. However, increased risk of endometrial cancer with long-term tamoxifen administration and of bone fracture due to osteoporosis in postmenopausal women undergoing aromatase inhibitor therapy are recognized side effects. These side effects as well as drug resistance make it necessary to search for novel molecular targets for drugs on the basis of well-characterized mechanisms of action. METHODS: Using accurate genome-wide expression profiles of breast cancers, we found maternal embryonic leucine-zipper kinase (MELK) to be significantly overexpressed in the great majority of breast cancer cells. To assess whether MELK has a role in mammary carcinogenesis, we knocked down the expression of endogenous MELK in breast cancer cell lines using mammalian vector-based RNA interference. Furthermore, we identified a long isoform of Bcl-G (Bcl-G(L)), a pro-apoptotic member of the Bcl-2 family, as a possible substrate for MELK by pull-down assay with recombinant wild-type and kinase-dead MELK. Finally, we performed TUNEL assays and FACS analysis, measuring proportions of apoptotic cells, to investigate whether MELK is involved in the apoptosis cascade through the Bcl-G(L)-related pathway. RESULTS: Northern blot analyses on multiple human tissues and cancer cell lines demonstrated that MELK was overexpressed at a significantly high level in a great majority of breast cancers and cell lines, but was not expressed in normal vital organs (heart, liver, lung and kidney). Suppression of MELK expression by small interfering RNA significantly inhibited growth of human breast cancer cells. We also found that MELK physically interacted with Bcl-G(L )through its amino-terminal region. Immunocomplex kinase assay showed that Bcl-G(L )was specifically phosphorylated by MELK in vitro. TUNEL assays and FACS analysis revealed that overexpression of wild-type MELK suppressed Bcl-G(L)-induced apoptosis, while that of D150A-MELK did not. CONCLUSION: Our findings suggest that the kinase activity of MELK is likely to affect mammary carcinogenesis through inhibition of the pro-apoptotic function of Bcl-G(L). The kinase activity of MELK could be a promising molecular target for development of therapy for patients with breast cancers

Hepatocytes undergo punctuated expansion dynamics from a periportal stem cell niche in normal human liver

Background & Aims: While normal human liver is thought to be generally quiescent, clonal hepatocyte expansions have been observed, though neither their cellular source nor their expansion dynamics have been determined. Knowing the hepatocyte cell of origin, and their subsequent dynamics and trajectory within the human liver will provide an important basis to understand disease-associated dysregulation. Methods: Herein, we use in vivo lineage tracing and methylation sequence analysis to demonstrate normal human hepatocyte ancestry. We exploit next-generation mitochondrial sequencing to determine hepatocyte clonal expansion dynamics across spatially distinct areas of laser-captured, microdissected, clones, in tandem with computational modelling in morphologically normal human liver. Results: Hepatocyte clones and rare SOX9+ hepatocyte progenitors commonly associate with portal tracts and we present evidence that clones can lineage-trace with cholangiocytes, indicating the presence of a bipotential common ancestor at this niche. Within clones, we demonstrate methylation CpG sequence diversity patterns indicative of periportal not pericentral ancestral origins, indicating a portal to central vein expansion trajectory. Using spatial analysis of mitochondrial DNA variants by next-generation sequencing coupled with mathematical modelling and Bayesian inference across the portal-central axis, we demonstrate that patterns of mitochondrial DNA variants reveal large numbers of spatially restricted mutations in conjunction with limited numbers of clonal mutations. Conclusions: These datasets support the existence of a periportal progenitor niche and indicate that clonal patches exhibit punctuated but slow growth, then quiesce, likely due to acute environmental stimuli. These findings crucially contribute to our understanding of hepatocyte dynamics in the normal human liver. Impact and implications: The liver is mainly composed of hepatocytes, but we know little regarding the source of these cells or how they multiply over time within the disease-free human liver. In this study, we determine a source of new hepatocytes by combining many different lab-based methods and computational predictions to show that hepatocytes share a common cell of origin with bile ducts. Both our experimental and computational data also demonstrate hepatocyte clones are likely to expand in slow waves across the liver in a specific trajectory, but often lie dormant for many years. These data show for the first time the expansion dynamics of hepatocytes in normal liver and their cell of origin enabling the accurate measurment of changes to their dynamics that may lead to liver disease. These findings are important for researchers determining cancer risk in human liver

Clonal transitions and phenotypic evolution in Barrett esophagus

BACKGROUND & AIMS: Barrett's esophagus (BE) is a risk factor for esophageal adenocarcinoma but our understanding of how it evolves is poorly understood. We investigated BE gland phenotype distribution, the clonal nature of phenotypic change, and how phenotypic diversity plays a role in progression. METHODS: Using immunohistochemistry and histology, we analyzed the distribution and the diversity of gland phenotype between and within biopsy specimens from patients with nondysplastic BE and those who had progressed to dysplasia or had developed postesophagectomy BE. Clonal relationships were determined by the presence of shared mutations between distinct gland types using laser capture microdissection sequencing of the mitochondrial genome. RESULTS: We identified 5 different gland phenotypes in a cohort of 51 nondysplastic patients where biopsy specimens were taken at the same anatomic site (1.0-2.0 cm superior to the gastroesophageal junction. Here, we observed the same number of glands with 1 and 2 phenotypes, but 3 phenotypes were rare. We showed a common ancestor between parietal cell-containing, mature gastric (oxyntocardiac) and goblet cell-containing, intestinal (specialized) gland phenotypes. Similarly, we have shown a clonal relationship between cardiac-type glands and specialized and mature intestinal glands. Using the Shannon diversity index as a marker of gland diversity, we observed significantly increased phenotypic diversity in patients with BE adjacent to dysplasia and predysplasia compared to nondysplastic BE and postesophagectomy BE, suggesting that diversity develops over time. CONCLUSIONS: We showed that the range of BE phenotypes represents an evolutionary process and that changes in gland diversity may play a role in progression. Furthermore, we showed a common ancestry between gastric and intestinal-type glands in BE

Alterations of the composition and spatial organization of the microenvironment following non-dysplastic Barrett’s esophagus through progression to cancer

Barrett’s esophagus (BE), a metaplastic condition that is the only known precursor for esophageal adenocarcinoma (EAC), is relatively common, but progression to cancer is infrequent. BE is inflamed but the contribution of the immune system to the carcinogenic process is unknown. To this end, we contrasted non-dysplastic metaplasia of BE patients, captured when they did not progress (non-progressors), did subsequently, but had not yet progressed (pre-progressors) or had already progressed to EAC (progressors). Using spatial multiplexed 56-protein analysis, serial laser capture microdissection (LCM) RNAseq and shallow whole genome sequencing, we identified prooncogenic immune neighbourhoods and dysregulated immune cell populations predictive of subsequent progression to EAC. Indeed, spatial analysis revealed that M1 macrophages, regulatory natural killer (NK) cells, neutrophils and altered ratios of intraepithelial CD4+ and CD8+ lymphocytes typify tumor microenvironmental (TME) changes associated with cancer initiation. Spatially derived cell-to-cell interactions revealed progression-specific immune cell interaction signatures predominantly involving M1 macrophages NK cells and plasma cells. Furthermore, LCM RNAseq analysis identified gene expression ‘hot’ signatures enriched in pre-progression and progression samples. Notably, we also observed a correlation between immune cells and copy number alterations in progressor metaplasia. By exposing coordinated changes in the immune cell landscape in patients at high risk of developing EAC, this multi-omic dataset provides novel diagnostic and therapeutic opportunitie

Single-cell paired-end genome sequencing reveals structural variation per cell cycle

The nature and pace of genome mutation is largely unknown. Because standard methods sequence DNA from populations of cells, the genetic composition of individual cells is lost, de novo mutations in cells are concealed within the bulk signal and per cell cycle mutation rates and mechanisms remain elusive. Although single-cell genome analyses could resolve these problems, such analyses are error-prone because of whole-genome amplification (WGA) artefacts and are limited in the types of DNA mutation that can be discerned. We developed methods for paired-end sequence analysis of single-cell WGA products that enable (i) detecting multiple classes of DNA mutation, (ii) distinguishing DNA copy number changes from allelic WGA-amplification artefacts by the discovery of matching aberrantly mapping read pairs among the surfeit of paired-end WGA and mapping artefacts and (iii) delineating the break points and architecture of structural variants. By applying the methods, we capture DNA copy number changes acquired over one cell cycle in breast cancer cells and in blastomeres derived from a human zygote after in vitro fertilization. Furthermore, we were able to discover and fine-map a heritable inter-chromosomal rearrangement t(1;16)(p36;p12) by sequencing a single blastomere. The methods will expedite applications in basic genome research and provide a stepping stone to novel approaches for clinical genetic diagnosis

Expression profiling of nuclear receptors in breast cancer identifies TLX as a mediator of growth and invasion in triple-negative breast cancer

The Nuclear Receptor (NR) superfamily of transcription factors comprises 48 members, several of which have been implicated in breast cancer. Most important is estrogen receptor-α (ERα), which is a key therapeutic target. ERα action is facilitated by co-operativity with other NR and there is evidence that ERα function may be recapitulated by other NRs in ERα-negative breast cancer. In order to examine the inter-relationships between nuclear receptors, and to obtain evidence for previously unsuspected roles for any NRs, we undertook quantitative RT-PCR and bioinformatics analysis to examine their expression in breast cancer. While most NRs were expressed, bioinformatic analyses differentiated tumours into distinct prognostic groups that were validated by analyzing public microarray data sets. Although ERα and progesterone receptor were dominant in distinguishing prognostic groups, other NR strengthened these groups. Clustering analysis identified several family members with potential importance in breast cancer. Specifically, RORγ is identified as being co-expressed with ERα, whilst several NRs are preferentially expressed in ERα-negative disease, with TLX expression being prognostic in this subtype. Functional studies demonstrated the importance of TLX in regulating growth and invasion in ERα-negative breast cancer cells.</p

The Peptidoglycan Recognition Protein 1 confers immune evasive properties on pancreatic cancer stem cells

[Objective]: Pancreatic ductal adenocarcinoma (PDAC) has limited therapeutic options, particularly with immune checkpoint inhibitors. Highly chemoresistant ‘stem-like’ cells, known as cancer stem cells (CSCs), are implicated in PDAC aggressiveness. Thus, comprehending how this subset of cells evades the immune system is crucial for advancing novel therapies.[Design]: We used the KPC mouse model (LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre) and primary tumour cell lines to investigate putative CSC populations. Transcriptomic analyses were conducted to pinpoint new genes involved in immune evasion. Overexpressing and knockout cell lines were established with lentiviral vectors. Subsequent in vitro coculture assays, in vivo mouse and zebrafish tumorigenesis studies, and in silico database approaches were performed.[Results]: Using the KPC mouse model, we functionally confirmed a population of cells marked by EpCAM, Sca-1 and CD133 as authentic CSCs and investigated their transcriptional profile. Immune evasion signatures/genes, notably the gene peptidoglycan recognition protein 1 (PGLYRP1), were significantly overexpressed in these CSCs. Modulating PGLYRP1 impacted CSC immune evasion, affecting their resistance to macrophage-mediated and T-cell-mediated killing and their tumourigenesis in immunocompetent mice. Mechanistically, tumour necrosis factor alpha (TNFα)-regulated PGLYRP1 expression interferes with the immune tumour microenvironment (TME) landscape, promoting myeloid cell-derived immunosuppression and activated T-cell death. Importantly, these findings were not only replicated in human models, but clinically, secreted PGLYRP1 levels were significantly elevated in patients with PDAC.[Conclusions]: This study establishes PGLYRP1 as a novel CSC-associated marker crucial for immune evasion, particularly against macrophage phagocytosis and T-cell killing, presenting it as a promising target for PDAC immunotherapy.JCL-G received support from a ’la Caixa’ Foundation (ID 100010434) fellowship (LCF/BQ/DR21/11880011) and an EMBO Scientific Exchange Fellowship (ID 10210). AP-C was a recipient of a Juan de la Cierva Formación 2020 (FJC2020- 044220-I) grant. This study was supported by a Fero Foundation Grant (BSJr.) and Rámon y Cajal Merit Award (RYC-2012-12104) from the Ministerio de Economía y Competitividad, Spain (BSJr.); received funding from the Beca Carmen Delgado/ Miguel Pérez-Mateo from AESPANC-ACANPAN Spain (BSJr), a Conquer Cancer Now Grant from the Concern Foundation (Los Angeles, CA, USA) (BSJr), a Coordinated grant (GC16173694BARB) from the Fundación Asociación Española Contra el Cáncer (AECC) (BSJr; AC), and FIS grants PI18/00757 and PI21/01110 (BSJr), PI19/00514 (CG) and PI22/00492 (VJSAL); and cofinanced through Fondo Europeo de Desarrollo Regional ’Una manera de hacer Europa’). We also acknowledge the support from CIBERONC (CB16/12/00446) (AC) and Ayudas de Consolidación y Estructuración de grupos from Consellería de Educación, Universidade y Formación profesional (ED431C-2028/28) and Programa de axudas á etapa posdotoral, both from Xunta de Galicia (LS, PCS). Projects were financed via MCIN/ AEI/FEDER (10.13039/501100011033) (REF-PID2021-125705OB-I00 (GdC) and REF-RTI2018- 095496-B-100) (GdC), and PID2021-124520OA-I00 and RYC2020-029767 (EE), and others including AECC (LABAE16017DECÁ, GdC and TRNSC213893ESPI, SG-M); the Clinical Research Priority Program ’ImmunoCure’ of the University of Zurich (CN-A), the German Research Foundation (SFB1292 Project Number 318346496, TPQ1 and TP22), GA1818/2-3 (MMG) as well as funding from an ERC Advanced Investigator Grant (Pa-CSC 233460, CH), the European Community’s Seventh Framework Programme (FP7) under grant agreement n° 602783 (CAM-PaC, CH), the Fondazione del Piemonte per l’Oncologia – IRCCS (PTCRC-Intra-2021, CH), the Fondazione AIRC per la ricerca sul cancro (IG 2023 ID 28933, CH), the Shanghai Municipal Education Commission (2021-01-07-00-02-E00090, CH), and the National Science Foundation China (82130074, CH).Peer reviewe