Tumor heterogeneity observed between patients has made it challenging to develop universal or broadly effective cancer therapies. Therefore, an ever-growing movement within cancer research aims to tailor cancer therapies to individual patients or specific tumor subtypes. Tumor stratification is generally dictated by the genomic mutation status of the tumor cells themselves. Importantly, non-genetic influences – such as interactions between tumor cells and other components of the tumor microenvironment – have largely been ignored. Therefore, in an effort to increase treatment predictability and efficacy, we investigated how tumor-stroma interactions contribute to drug sensitivity and drug resistance. I designed a high throughput co-culture screening platform to measure how tumor-stroma interactions alter drug mediated cell death. I identified tumor-stroma interactions that strongly desensitize or sensitize cancer cells to various drug treatments. The directionality of these observed phenotypes was dependent on the stromal cell tissue of origin. Further study revealed that interactions between tumor cells and fibroblasts modulate apoptotic priming in tumor cells to mediate sensitivity to chemotherapeutics. The principles uncovered in this study have important implications on the use of drugs that are designed to enhance apoptosis. For example, based on our screening data, I hypothesized and experimentally validated that the effectiveness of BH3 mimetic compounds would be strongly dependent on the fibroblast growth environment. Taken together, our study highlights the importance of understanding how environmental interactions alter the drug responses of cancer cells and reveals a mechanism by which stromal cells drive broad spectrum changes in tumor cell sensitivities to common chemotherapeutics.

<p>Triple Negative Breast Cancer (TNBC) is the most aggressive type of breast cancer. TNBC patients are resistant to virtually all target therapies and suffer a higher post-chemotherapy relapse with a worse overall survival compared with other types of breast cancers. Therefore, the development of an effective therapy is urgently needed. PKM2 plays a prominent role in mediating<b> </b>tumor glycolysis and PKM2 is often overexpressed in human cancers. However, whether PKM2 mediated glycolysis is necessary for cancer cell growth is questionable. Here, I have found that inhibition of PKM2 does not affect TNBC cell growth due to a metabolic switch from glycolysis to fatty acid oxidation (FAO). We show that PKM2 directly interacts with EZH2 to coordinately mediate epigenetic silencing of SLC16A9, transporter of a key player in FAO, Carnitine. Inhibition of either PKM2 or EZH2 increases levels of SLC16A9 and intracellular Carnitine to promote FAO and thereby sustains cancer cell growth. Direct inhibition of EZH2 using a clinically tested EZH2 inhibitor, GSK126, is able to elicit a previously unidentified vulnerability to a clinically tested FAO inhibitor, Etomoxir. As a result, combined GSK126-Etomoxir treatment synergistically abolishes TNBC xenograft tumor growth in vivo. Together, this study uncovers PKM2-EZH2 mediated metabolic reprogramming that leads to a new drug combination therapy by dual targeting of EZH2 and FAO for effective treatment of TNBC.<b> </b></p> <p> </p> <p>Furthermore, Dendritic Cell (DC) vaccination has shown promise in treating cancer patients. However, the <i>in vitro</i> generation of a fully functional DC remains a big challenge in this field. EZH2 inhibition has shown to be able to create an immunologically ‘hot’ tumors. Nonetheless, the role of EZH2 in regulation of DC function is still unclear. I found that the expression levels of EZH2 and its functional maker, H3K27Me3, are enhanced following maturation from immature DC (iDC) into two functional DCs, α-type 1-polarized-DC (αDC) and gold standard DC (sDC). Moreover, inhibition of EZH2 by GSK126 treatment elicits a dependency of sDC on FAO. These results suggest that EZH2 plays a role in maturation of DC through metabolic reprogramming, which may also provide new DC based immunotherapy of TNBC. </p>

Despite progress being made in our understanding of triple negative breast cancer (TNBC), the overall survival and disease-free survival for TNBC patients continues to be considerably poorer than their ER/PR/HER2+ counterparts. Metastasis and chemoresistance are the pivotal issues holding back the long-term success of TNBC treatments. In addition to the bulk tumor cells, cancer stem cells (CSCs) have emerged as important targets for alleviating TNBC progression and relapse. Cisplatin, a platinum based chemotherapeutic agent, has shown promising potential for the treatment of TNBC in clinical trials; however, cisplatin treatment is associated with tumor hypoxia that in turn promotes CSC enrichment and drug resistance. My work is to develop a combinational treatment to improve the long-term therapeutic potential of cisplatin that not only targeted the bulk TNBC population but also ALDHhigh and CD44+/CD24- CSC populations. Through clinical dataset analysis, I found that patient TNBC tumors expressed high levels of epidermal growth factor receptor (EGFR) and hypoxia genes. A similar expression pattern was demonstrated in cisplatin-resistant ovarian cancer. I therefore developed a combinational therapeutic to co-inhibit EGFR and hypoxia using metformin (an AMPK activator) and gefitinib (an EGFR inhibitor), which sensitized bulk TNBC cells to cisplatin and also led to the effective inhibition of both CD44+/CD24- and ALDHhigh CSCs. I obtained similar results by using clinically relevant TNBC patient samples ex vivo. Since these drugs are already frequently used in the clinic, this study illustrates a novel, clinically translatable therapeutic approach to improve the long-term therapeutic outcome of cisplatin for TNBC treatment.

Breast cancer is a multifaceted disease that affects 1 in every 8 women. Triple negative breast cancer (TNBC) accounts for ~15-20% of all diagnosed breast cancers and is characterized by the absence of ER, PR, and HER2 on the tumor cell surface. As most cancer therapies to date target these cell surface receptors, TNBC is the only subtype of breast cancer without a targeted therapy and thus prognosis for it remains poor. The heterogeneity of TNBC also makes finding a targeted therapy particularly difficult. This work focuses on different methods of targeting distinct subpopulations of TNBC in order to identify potential novel therapeutic nodes to exploit as targeted therapies. The first chapter describes the use of a directed siRNA synthetic lethality screen to target vulnerabilities associated with basal TNBC, the most common TNBC subtype. The screen identified multiple dependency genes associated with RNA splicing, particularly those in the U4/U6.U5 tri-snRNP complex (PRPF8, PRPF38A). Depletion of these genes or the upstream splicing inhibitor E7107 in basal TNBC cell lines resulted in intronic retention and altered splicing of transcripts in pathways necessary for TNBC survival, including mitosis and apoptosis. In vivo, E7107 hindered the growth of both basal cell line and patient derived xenographs, a phenotype that was enhanced with the addition of the proteasome inhibitor bortezomib. This suggests that splicing and proteasome inhibition could be an effective basal TNBC treatment. The second chapter investigates the role of G-Protein Pathway Suppressor 2 (GPS2) as a tumor suppressor in the PI3K/AKT pathway in TNBC. Previous work has shown that GPS2 acts as a negative regulator of this pathway through inhibition of Ubc13-mediated activation of AKT in the insulin signaling pathway. In this study, MDA-MB231-GPS2KO cells were found to have increased proliferative, migratory, and invasive properties, which were rescued upon treatment with the allosteric AKT inhibitor MK2206. In vivo, GPS2 depleted cells conferred greater tumor burden in an orthotopic mouse model that was also responsive to AKT inhibition. Transcriptomic analysis showed significant overlap between MB231-GPS2KO and MB231 cells modified to have constitutively active AKT, indicating that the phenotypes observed in MB231-GPS2KO were at least in part due to loss of GPS2-mediated regulation of AKT activation. These studies point to GPS2 as a potential biomarker for a subclass of breast cancers that would be responsive to PI3K-class inhibitor drugs. In sum, these studies elucidate interactions and processes that seem to specifically adversely affect TNBC cells, which broaden our knowledge of TNBC biology and its potential weaknesses. / 2022-03-03T00:00:00Z

Tesis por compendio / [ES] La inmunoterapia es un tratamiento prometedor para el cáncer de mama triple negativo (TNBC), pero los pacientes recaen, lo que destaca la necesidad de comprender los mecanismos de resistencia. En esta tesis doctoral hemos descubierto que, en el tumor primario de cáncer de mama, las células tumorales que resisten el ataque de los linfocitos T son quiescentes. Las células cancerosas quiescentes (QCC) forman nichos con baja infiltración inmune. Estas células QCC exhiben mayor capacidad de regenerar tumores 2 y tienen un perfil de expresión génica relacionado con resistencia a quimioterapia y pluripotencia. Adaptamos la secuenciación de ARN unicelular para obtener también una resolución espacial precisa que nos permitiese analizar los infiltrados dentro y fuera del nicho de QCC. Este análisis transcriptómico reveló la inducción de programas relacionados con la hipoxia e identificó células T más agotadas, fibroblastos supresores y células dendríticas disfuncionales dentro de las áreas de QCC. Esto pone de manifiesto los fenotipos diferenciales en las células infiltrantes según su ubicación intratumoral. Fuimos capaces además de identificar la activación HIF1a específicamente en las QCC como el responsable del fenotipo de exclusión y disfuncionalidad inmune. La activación forzada de HIF1a en células tumorales era suficiente para recapitular el fenotipo observado en las áreas con QCC. Por todo esto, hemos demostrado que las QCC constituyen reservorios resistentes a la inmunoterapia al orquestar un medio inmunosupresor hipóxico localizado que bloquea la función de las células dendríticas y por tanto de los linfocitos T. La eliminación de las QCC es la clave que promete contrarrestar la resistencia a la inmunoterapia y prevenir la recurrencia de la enfermedad en el TNBC. / [CA] La immunoteràpia és un tractament prometedor per al càncer de mama triple negatiu (TNBC), però els pacients recauen, fent destacar la necessitat de comprendre els mecanismes de resistència. En aquesta tesi doctoral hem descobert que al tumor primari de càncer de mama, les cèl·lules tumorals que resisteixen l'atac dels limfòcits T són quiescents. Les cèl·lules canceroses quiescents (QCC) formen nínxols amb baixa infiltració immune. Aquestes cèl·lules QCC exhibeixen més capacitat de regenerar tumors i tenen un perfil d'expressió gènica relacionat amb resistència a quimioteràpia i pluripotència. Hem adaptat la sequ¿enciació d'ARN unicel·lular per obtenir també una resolució espacial precisa que ens permetés analitzar els infiltrats dins i fora del nínxol de QCC. Aquesta anàlisi transcriptòmica va revelar la inducció de programes relacionats 3 amb la hipòxia i va identificar cèl·lules T més esgotades, fibroblasts supressors i cèl·lules dendrítiques disfuncionals dins de les àrees de QCC. Això posa de manifest els fenotips diferencials a les cèl·lules infiltrants segons la seva ubicació intratumoral. Vam ser capaços a més d'identificar l'activació de HIF1a específicament a les QCC com a responsable del fenotip d'exclusió i disfuncionalitat immune. L'activació forçada de HIF1a en cèl·lules tumorals era suficient per recapitular el fenotip observat a les àrees amb QCC. Per tot això, hem demostrat que les QCC constitueixen reservoris resistents a la immunoteràpia en orquestrar un micro-ambient immunosupressor hipòxic localitzat que bloqueja la funció de les cèl·lules dendrítiques i per tant dels limfòcits T. L'eliminació de les QCC és la clau que promet contrarestar la resistència a la immunoteràpia i prevenir la recurrència de la malaltia al TNBC. / [EN] Immunotherapy is a promising treatment for Triple-Negative Breast Cancer (TNBC), but many patients relapse or do not respond, highlighting the need to understand mechanisms of resistance. In this doctoral thesis we discovered that in primary breast cancer, tumor cells that resist T cell attack are quiescent. These Quiescent Cancer Cells (QCCs) form clusters with reduced immune infiltration. They also display superior tumorigenic capacity and higher expression of chemotherapy resistance and stemness genes. We adapted single-cell-RNA-sequencing with precise spatial resolution to profile infiltrating cells (stromal and immune cells) inside and outside the QCC niche. This transcriptomic analysis revealed hypoxia-induced programs and identified the presence of more abundant exhausted T-cells, tumor-protective fibroblasts, and dysfunctional dendritic cells inside clusters of QCCs. This uncovered differential phenotypes in infiltrating cells based on their intra-tumor location with respect to QCCs. We were also able to identify HIF1a expression in QCC as the driver of immune exclusion and dysfunction. Forced activation of a HIF1a program in cancer cells recapitulated the immune phenotype observed in the QCCs' niche. Thus, QCCs constitute immunotherapyresistant reservoirs by orchestrating a local immune-suppressive milieu that blocks DC activation impairing T-cell function. Eliminating QCCs holds the promise to counteract immunotherapy resistance and prevent disease recurrence in TNBC. / Baldominos Flores, P. (2024). Study of immune resistant mechanisms in mouse models of breast cancer [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/203657 / Compendio

Philosophiae Doctor - PhD / Globally, breast cancer is the most common cancer affecting women and it is predicted that in 2030 about 12 million deaths will occur with approximately 21.7 million new cases [2]. Genetic risk factors as well as race and ethnicity, account for about 5-10% of all breast cancer occurrences. Triple negative breast cancer (TNBC), tumors that tested negative for oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2), contribute to 10-20% of all breast carcinomas [3,4] and is known to be a more aggressive type of cancer with varying degree of response to chemotherapeutic and radiation therapy [5,6] / 2022-02-24

<p>One in eight woman develop breast cancer in the United States of America and is the most common type of cancer in the world. Breast cancer has the highest rate of death compared to any other form of cancer. Triple Negative Breast Cancer (TNBC) is the most lethal type of breast cancer, which is the most fatal of all breast cancer types. TNBC is onerous to treat since it lacks all the three most commonly targeted hormones and receptors. Current patients afflicted with TNBC are treated with platinum core chemotherapeutics, namely Cisplatin. Despite the anticancer effects shown by Cisplatin, TNBC attenuates its effect and develops a resistance eventually, which results in reoccurrence of TNBC after few years. Hence there is a demand for effective and alternative ways to treat TNBC. To inhibit the TNBC cell proliferation, blocking the key glycolytic enzyme Lactase Dehydrogenase B (LDHB) is studied and validated. Galloflavin (GF), a proven LDHB inhibitor is utilized in this series of studies and analysis. In addition, Electrochemotherapy, which involves the application of electrical pulses (EP) were utilized to enhance the uptake of GF. The combination of Electrochemotherapy (ECT) with LDHB is a novel way to treat TNBC to produce an alternative to traditional chemotherapy. EP+GF will be subjected onto TNBC cells at various concentrations and pulse parameters. The purpose of this study is to test the effect of alternative chemotherapeutic drug delivery methods for TNBC patients for decrease in mortality rate and improve quality of life. Results indicate TNBC cell viability is the least for EP+GF treatments and the maximum Reactive Oxygen Species (ROS) levels and a maximum decrease in Glucose and Lactate uptake for EP+GF treatments relative to control. Immunoblotting studies indicate the inhibition of LDHB is the most on EP+GF treatments, indicating that this could be a novel modality to treat TNBC.<br></p>

Introduction: Breast cancer is the second highest cause of cancer mortality in women worldwide. Hormonal therapy is considered one of the most effective therapies and is used against luminal-type malignancies. However, 40-50% of tumour cells can develop resistance, thereby limiting the success in breast cancer treatment. In this study, mechanisms of resistance were investigated using a novel multi-stable isotope labelled amino acids (SILAC) proteomics approach in phenotype-specific breast cancer cell lines resistant to endocrine treatment. Method: In vitro chemo-sensitivity (IC50) was determined for MCF7, T47D, MDA-MB-231, MDA-MB-468, MDA-MB-453, BT-20 and MCF-10A breast cell lines using four endocrine-based therapeutic agents (Tamoxifen, 4-Hydroxytamoxifen OHT, Raloxifene, Anastrozole) to select viable strains for resistance studies. MCF7 (luminal-type A) and MDA-MB-231 (triple negative breast cancer, TNBC) were selected and initially subject to OHT or raloxifene exposure with gradual increments for 10 months. WT cells were grown in the absence of drug in parallel as passage controls. Resistant cell lines were assessed by MTT and IF for comparison with parental cell lines. Resistant cell lines, along with the passage control and a SILAC control, were grown in “light” SILAC medium together with WT strains cultured in “heavy” SILAC medium. Proteins were extracted, concentrations determined and analysed by SDS PAGE for quality control. An aliquot of each “light” cell line (resistant, passage control or SILAC control) was combined with an equal amount of “heavy” WT, trypsin digested and analysed by nano-HPLC Orbitrap Fusion mass spectrometry (2D-LC MS/MS). Proteins were identified by database searching using MascotTM. Relative changes (resistant/WT ratio) in protein levels were determined and bioinformatics tools (STRING and UniProt) used to explore significantly changed pathways associated with resistance. Western blotting was used to verify selected target proteins. Results: Four consistently resistant sublines were generated MCF7 OHT Res (2.00-fold more resistant), MCF7 Ralx Res (2.00-fold), MDA-MB-231 OHT Res (1.90-fold change) and MDA-MB-231 Ralx Res (2.00-fold), in addition to two high passage controls. ER expression by IF was decreased in MCF7 OHT Res compared to the WT and MCF7 Ralx Res, whereas CD44 was increased. Proteomic analysis revealed 2247 and 2880 total proteins in MCF7 OHT Res and MCF7 Ralx Res whilst 3471 and 3495 total proteins were identified in MDA-MB-231 OHT Res and MDA-MB-231 Ralx Res, respectively. Bioinformatics tools identified significantly changed pathways included apoptosis, cytoskeleton, cell motility and redox cell homeostasis. Components of the MAPK-signalling cascade were consistently found to be upregulated in resistant cell lines. MAPK1 (ERK2), previously associated with tamoxifen resistance was increased in MDA-MB-231 Ralx Res cell lines by 4.45-fold and confirmed by Western blotting. Sorcin, which contributes to calcium homeostasis and is also linked to multidrug resistance was increased 4.11- and 2.35-fold in MCF7 OHT Res and Ralx Res sub cell lines, respectively. Some results, such as those for c-Jun, were inconsistent between proteomic analysis and Western blotting and require further investigation. Conclusion: The unique resistant cell lines generated here, as well the MCF7 OHT resistant line, provided novel data that give insights into the biological pathways involved in mechanisms of endocrine drug resistance in breast cancer. Proteomics analysis provided extensive data on common functionality and pathways across the resistant cell lines independent of phenotype or SERM. Overall, the results provided interesting targets for re-sensitising resistant breast cancer and the potential to investigate novel combination therapies in the future. / Al-Ahliyya Amman University scholaships

Poly-(ADP-ribsoyl) Polymerases (PARPs) are a superfamily of enzymes comprised of 17 known isoforms. PARP inhibitors (PARPi) have shown success in clinical trials for the treatment of homologous recombination-deficient cancers. Though proven effective initially, tumors treated with PARPi eventually develop resistance. Combinatorial therapeutics targeting PARP and other pathways that may re-sensitize tumors to PARP inhibition, including PI3K/AKT/mTor pathway, and cell-cycle checkpoints (such as CDKs, CHK, and Wee) are being tested. In this context, the synthetic lethality of cyclin-dependent kinase 1 (CDK1) and PARP1 is known. Evaluation of PARP1 and CDK1 pharmacophores led to the development of the tetrahydro-arylazepinone (TAAP) scaffold as a potential dual PARP1/CDK1 inhibitor. We screened a handful of TAAP analogs against PARP1 in a cell-free assay that identified the low micromolar PARP1 inhibitor 1,2,3,4-tetrahydro-5H-benzo[e][1,4]-diazepin-5-one (TBAP), which served as the lead compound. The analogous 1,2,3,4-tetrahydro-5H-pyrido[2,3-e][1,4]-diazepin-5-one (TPAP) series showed a similar bioactivity profile. Satisfyingly, the N1-benzyl TPAP analogue showed activity in the low nanomolar range. The TAAP series (i.e., 6/7-membered scaffold) unfortunately lacked CDK1 inhibitory activity. Finally, many PARPi's show poor isoform-selectivity. The development of isoform-selective PARPi can clarify the specific function of each PARP isoform and may reduce the adverse side effects shown by PARPi. A handful of TAAP analogs were screened against 13 PARP isoforms, where some compounds demonstrated exquisite PARP1/2 selectivity. Concurrently, we discovered an inhibitor for PARP11, an isoform that lacks any known synthetic ligand. Future directions are suggested towards fine-tuning the structure-activity relationship of TAAP-isoform selective PARPi as well as developing a dual PARP1/CDK1 inhibitor. / Master of Science

Breast cancer is the most prevalent cancer in women in the UK with over 50,000 new cases diagnosed each year. Almost all breast cancer deaths are due to metastatic disease. The RUNX1-CBFbeta transcription factor complex has been implicated in the development of human breast cancer and recent evidence from our laboratory indicated that it might have a role in metastasis. The aim of this project was therefore to determine the role of the RUNX1 transcription factor in breast cancer metastasis. Initial experiments to knockdown RUNX1 by shRNA also decreased the expression of RUNX2. Therefore, due to the off-target effect of shRUNX1, CRISPR-Cas9n was used to establish a RUNX1-negative cell line by targeting the first exon of the RUNX1 gene. Migration and invasion capacity of the cells decreased in the absence of RUNX1 and it was comparable to the absence of RUNX2 and CBFbeta respectively, which are known to play roles in migration and invasion of MDA-MB-231 cells. The cells also formed spherical clusters in 3D culture which was associated with the changes in cell morphology from stellate to round shape in the absence of RUNX1. The expression of the metastasis-related genes MMP13, MMP9, OPN and SLUG also decreased in parallel with the loss of the mesenchymal-like phenotype whilst the expression of the epithelial markers cytokeratin, desmoplakin and E-cadherin increased concomitantly. Importantly, re-expression of RUNX1 in the RUNX1-negative cell lines using an inducible expression system rescued migration and invasion. Therefore, RUNX1 is required to maintain the mesenchymal-like phenotype of MDA-MB-231 cells and hence is important for the epithelial to mesenchyme transition (EMT), a key characteristic of metastatic cells. The transcription factor SLUG is a known regulator of EMT. Data obtained shows that RUNX1 down-regulates the expression of SLUG. ChIP analysis demonstrated that RUNX1 was bound to the SLUG promoter and RUNX1 was subsequently shown to activate the promoter activity. Finally, experiments to inhibit the activity of the RUNX transcription factors pharmacologically showed changes in cell differentiation and also affected cell viability, possibly by off-target effects. Taken together, data presented in this work demonstrates that RUNX1 is required for EMT in the metastatic breast cancer cells and it is therefore a potential therapeutic target to prevent breast cancer metastasis.