WT1 role in mammary gland and breast cancer biology

The Wilms' Tumour Suppressor gene 1, WT1, encodes for a complex protein which is essential in mammals throughout life. Its roles vary with the developmental stages: in the embryo, it regulates the epithelial-mesenchymal balance required for a correct organogenesis and acts as a tumour suppressor; in the adult, it is involved in the maintenance of tissue homeostasis and has been controversially considered as an oncogene. Breast cancer is one of the adult tumours in which WT1 oncogenic function was first hypothesised. This malignancy is the most common in women, with more than one million cases being diagnosed worldwide every year, and represents the leading cause of cancer related deaths. Because of its major health burden, this disease has been extensively studied and special attention has also been paid to normal mammary gland biology: several works have shown that breast cancer can be divided into many molecular subtypes, which may reflect the cell of origin of the tumour; moreover, many genes involved in the normal development of the mammary gland have been proven to also play a role in breast tumorigenesis. WT1 expression has been previously reported in both healthy mammary glands and breast cancer samples, however, its function in this context is not well understood and the evidence gathered so far is extremely contradictory. This thesis aimed to investigate the exact role played by WT1 in both mammary gland and breast cancer biology, using a combination of in vivo and in vitro techniques. Following flow cytometry isolation, Wt1 mRNA expression was detected in the myoepithelial and stem cell subpopulations of the healthy gland. To investigate the effects of WT1 loss, Wt1 conditional mice were crossed with two different mammary specific Cre lines: the knockout animals developed, bred and lactated normally, however, they showed a significant increase of ductular branches during pregnancy, suggesting that WT1 may be involved in the regulation of branching morphogenesis. In order to study WT1 role in mammary tumours, the gene was knocked out in a breast cancer mouse model and knocked down in several breast cancer cell lines, using both constitutive and inducible lentivirus-based systems. WT1 loss did not seem to affect cell proliferation, but resulted in a significant increase in cell migration in vitro and in the upregulation of mesenchymal markers. Furthermore, bioinformatics analysis showed that the WT1-positive tumours mainly belong to the luminal/ER-positive subtypes and express lower levels of mesenchymal markers than the WT1-negative tumours. As a whole, the findings of this thesis characterise WT1 expression in the healthy mammary gland and provide the first evidence of its possible function in this organ; moreover, this work seems to rule out an oncogenic role for WT1 in breast cancer, while suggesting that it could be an upstream regulator of cell migration. Additional experiments are required to confirm this result in vivo and verify whether it could lead to any clinical application

Transcription factor, Wilms’ Tumour 1 regulates developmental RNAs through 3’ UTR interaction.

Wilms' tumor 1 (WT1) is essential for the development and homeostasis of multiple mesodermal tissues. Despite evidence for post-transcriptional roles, no endogenous WT1 target RNAs exist. Using RNA immunoprecipitation and UV cross-linking, we show that WT1 binds preferentially to 3' untranslated regions (UTRs) of developmental targets. These target mRNAs are down-regulated upon WT1 depletion in cell culture and developing kidney mesenchyme. Wt1 deletion leads to rapid turnover of specific mRNAs. WT1 regulates reporter gene expression through interaction with 3' UTR-binding sites. Combining experimental and computational analyses, we propose that WT1 influences key developmental and disease processes in part through regulating mRNA turnover

WT1 expression in breast cancer disrupts the epithelial/mesenchymal balance of tumour cells and correlates with the metabolic response to docetaxel

WT1 is a transcription factor which regulates the epithelial-mesenchymal balance during embryonic development and, if mutated, can lead to the formation of Wilms' tumour, the most common paediatric kidney cancer. Its expression has also been reported in several adult tumour types, including breast cancer, and usually correlates with poor outcome. However, published data is inconsistent and the role of WT1 in this malignancy remains unclear. Here we provide a complete study of WT1 expression across different breast cancer subtypes as well as isoform specific expression analysis. Using in vitro cell lines, clinical samples and publicly available gene expression datasets, we demonstrate that WT1 plays a role in regulating the epithelial-mesenchymal balance of breast cancer cells and that WT1-expressing tumours are mainly associated with a mesenchymal phenotype. WT1 gene expression also correlates with CYP3A4 levels and is associated with poorer response to taxane treatment. Our work is the first to demonstrate that the known association between WT1 expression in breast cancer and poor prognosis is potentially due to cancer-related epithelial-to-mesenchymal transition (EMT) and poor chemotherapy response

Enhanced Immunogenicity of Mitochondrial-Localized Proteins in Cancer Cells.

Epitopes derived from mutated cancer proteins elicit strong antitumor T-cell responses that correlate with clinical efficacy in a proportion of patients. However, it remains unclear whether the subcellular localization of mutated proteins influences the efficiency of T-cell priming. To address this question, we compared the immunogenicity of NY-ESO-1 and OVA localized either in the cytosol or in mitochondria. We showed that tumors expressing mitochondrial-localized NY-ESO-1 and OVA proteins elicit significantdly higher frequencies of antigen-specific CD8+ T cells in vivo. We also demonstrated that this stronger immune response is dependent on the mitochondrial location of the antigenic proteins, which contributes to their higher steady-state amount, compared with cytosolic localized proteins. Consistent with these findings, we showed that injection of mitochondria purified from B16 melanoma cells can protect mice from a challenge with B16 cells, but not with irrelevant tumors. Finally, we extended these findings to cancer patients by demonstrating the presence of T-cell responses specific for mutated mitochondrial-localized proteins. These findings highlight the utility of prioritizing epitopes derived from mitochondrial-localized mutated proteins as targets for cancer vaccination strategies.S

Promises and challenges of adoptive T-cell therapies for solid tumours

From Springer Nature via Jisc Publications RouterHistory: received 2020-11-09, rev-recd 2021-02-22, accepted 2021-03-04, registration 2021-03-04, pub-electronic 2021-03-29, online 2021-03-29, pub-print 2021-05-25Publication status: PublishedFunder: DH | National Institute for Health Research (NIHR); doi: https://doi.org/10.13039/501100000272; Grant(s): RCF18/046Funder: Ovarian Cancer Action; doi: https://doi.org/10.13039/501100000299; Grant(s): HER000762Abstract: Cancer is a leading cause of death worldwide and, despite new targeted therapies and immunotherapies, many patients with advanced-stage- or high-risk cancers still die, owing to metastatic disease. Adoptive T-cell therapy, involving the autologous or allogeneic transplant of tumour-infiltrating lymphocytes or genetically modified T cells expressing novel T-cell receptors or chimeric antigen receptors, has shown promise in the treatment of cancer patients, leading to durable responses and, in some cases, cure. Technological advances in genomics, computational biology, immunology and cell manufacturing have brought the aspiration of individualised therapies for cancer patients closer to reality. This new era of cell-based individualised therapeutics challenges the traditional standards of therapeutic interventions and provides opportunities for a paradigm shift in our approach to cancer therapy. Invited speakers at a 2020 symposium discussed three areas—cancer genomics, cancer immunology and cell-therapy manufacturing—that are essential to the effective translation of T-cell therapies in the treatment of solid malignancies. Key advances have been made in understanding genetic intratumour heterogeneity, and strategies to accurately identify neoantigens, overcome T-cell exhaustion and circumvent tumour immunosuppression after cell-therapy infusion are being developed. Advances are being made in cell-manufacturing approaches that have the potential to establish cell-therapies as credible therapeutic options. T-cell therapies face many challenges but hold great promise for improving clinical outcomes for patients with solid tumours

Promises and challenges of adoptive T-cell therapies for solid tumours.

Cancer is a leading cause of death worldwide and, despite new targeted therapies and immunotherapies, many patients with advanced-stage- or high-risk cancers still die, owing to metastatic disease. Adoptive T-cell therapy, involving the autologous or allogeneic transplant of tumour-infiltrating lymphocytes or genetically modified T cells expressing novel T-cell receptors or chimeric antigen receptors, has shown promise in the treatment of cancer patients, leading to durable responses and, in some cases, cure. Technological advances in genomics, computational biology, immunology and cell manufacturing have brought the aspiration of individualised therapies for cancer patients closer to reality. This new era of cell-based individualised therapeutics challenges the traditional standards of therapeutic interventions and provides opportunities for a paradigm shift in our approach to cancer therapy. Invited speakers at a 2020 symposium discussed three areas-cancer genomics, cancer immunology and cell-therapy manufacturing-that are essential to the effective translation of T-cell therapies in the treatment of solid malignancies. Key advances have been made in understanding genetic intratumour heterogeneity, and strategies to accurately identify neoantigens, overcome T-cell exhaustion and circumvent tumour immunosuppression after cell-therapy infusion are being developed. Advances are being made in cell-manufacturing approaches that have the potential to establish cell-therapies as credible therapeutic options. T-cell therapies face many challenges but hold great promise for improving clinical outcomes for patients with solid tumours

Dose-Dependent Onset of Regenerative Program in Neutron Irradiated Mouse Skin

Background: Tissue response to irradiation is not easily recapitulated by cell culture studies. The objective of this investigation was to characterize, the transcriptional response and the onset of regenerative processes in mouse skin irradiated with different doses of fast neutrons. Methodology/Principal Findings: To monitor general response to irradiation and individual animal to animal variation, we performed gene and protein expression analysis with both pooled and individual mouse samples. A high-throughput gene expression analysis, by DNA oligonucleotide microarray was done with three months old C57Bl/6 mice irradiated with 0.2 and 1 Gy of mono-energetic 14 MeV neutron compared to sham irradiated controls. The results on 440 irradiation modulated genes, partially validated by quantitative real time RT-PCR, showed a dose-dependent up-regulation of a subclass of keratin and keratin associated proteins, and members of the S100 family of Ca2+-binding proteins. Immunohistochemistry confirmed mRNA expression data enabled mapping of protein expression. Interestingly, proteins up-regulated in thickening epidermis: keratin 6 and S100A8 showed the most significant up-regulation and the least mouse-to-mouse variation following 0.2 Gy irradiation, in a concerted effort toward skin tissue regeneration. Conversely, mice irradiated at 1 Gy showed most evidence of apoptosis (Caspase-3 and TUNEL staining) and most 8-oxo-G accumulation at 24 h post-irradiation. Moreover, no cell proliferation accompanied 1 Gy exposure as shown by Ki67 immunohistochemistry. Conclusions/Significance: The dose-dependent differential gene expression at the tissue level following in vivo exposure to neutron radiation is reminiscent of the onset of re-epithelialization and wound healing and depends on the proportion of cells carrying multiple chromosomal lesions in the entire tissue. Thus, this study presents in vivo evidence of a skin regenerative program exerted independently from DNA repair-associated pathways

Role of immunotherapy in ovarian cancer: a narrative review

Background and Objective: Ovarian cancer (OC) is a deadly gynaecological cancer with limited successful treatment options; approximately 70–80% of patients relapse, even those who initially respond well to treatment. It has been recently suggested that relapse occurs due to dormancy, an inactive cellular state which can evade traditional therapeutics targeting highly proliferating cells through different mechanisms. One is immune evasion, which conceals tumour cells from the body’s natural defence system. The cells can modulate their immunogenicity and that of the host to overcome the opposing tumour-immune system operation. Therefore, developing immunotherapies, which function to arm the host immune system against the tumour, is vital to patient survival. Considering the successes of immunotherapies in other cancers, this review will outline various tumour immune evasion strategies within its complex microenvironment and examine current significant developments in immunotherapies to inflame the ovarian tumour and overcome the resistance such that no cell is left behind. Methods: A PubMed search prioritising all types of literature since 2010 was conducted using the keywords “ovarian cancer”, “epithelial ovarian cancer”, “immunotherapy”, “immune evasion”, and “relapse” in various combinations. Secondary searches and other citations were based off reference lists. Key Content and Findings: Numerous molecular and cellular modifications are utilised by OC cells to evade the immune system. Further, the tumour microenvironment creates a physical barrier to immune infiltration and an immunosuppressive environment. In response, many immunotherapies have been created to combat OC, including antibodies, vaccines, adoptive cell therapy (ACT), immunomodulators and immunogenic cell death (ICD) inducers. Conclusions: Most immunotherapies targeting OC are still in early stages and far from being used clinically. While combination therapy is suggested, it may also be beneficial to recruit various types of immune cells to the tumour. Awareness of immune evasion strategies is critical to treatment development and targeting relapse