Cancer Cell Plasticity Research Articles

Loss of SNAI1 induces cellular plasticity in invasive triple-negative breast cancer cells

The transcription factor SNAI1 mediates epithelial-mesenchymal transition, fibroblast activation and controls inter-tissue migration. High SNAI1 expression characterizes metastatic triple-negative breast carcinomas, and its knockout by CRISPR/Cas9 uncovered an epithelio-mesenchymal phenotype accompanied by reduced signaling by the cytokine TGFβ. The SNAI1 knockout cells exhibited plasticity in differentiation, drifting towards the luminal phenotype, gained stemness potential and could differentiate into acinar mammospheres in 3D culture. Loss of SNAI1 de-repressed the transcription factor FOXA1, a pioneering factor of mammary luminal progenitors. FOXA1 induced a specific gene program, including the androgen receptor (AR). Inhibiting AR via a specific antagonist regenerated the basal phenotype and blocked acinar differentiation. Thus, loss of SNAI1 in the context of triple-negative breast carcinoma cells promotes an intermediary luminal progenitor phenotype that gains differentiation plasticity based on the dual transcriptional action of FOXA1 and AR. This function of SNAI1 provides means to separate cell invasiveness from progenitor cell de-differentiation as independent cellular programs.

In vivo 3D profiling of site-specific human cancer cell morphotypes in zebrafish.

Tissue microenvironments affect the functional states of cancer cells, but determining these influences in vivo has remained a challenge. We present a quantitative high-resolution imaging assay of single cancer cells in zebrafish xenografts to probe functional adaptation to variable cell-extrinsic cues and molecular interventions. Using cell morphology as a surrogate readout of cell functional states, we examine environmental influences on the morphotype distribution of Ewing Sarcoma, a pediatric cancer associated with the oncogene EWSR1-FLI1 and whose plasticity is thought to determine disease outcome through non-genomic mechanisms. Computer vision analysis reveals systematic shifts in the distribution of 3D morphotypes as a function of cell type and seeding site, as well as tissue-specific cellular organizations that recapitulate those observed in human tumors. Reduced expression of the EWSR1-FLI1 protein product causes a shift to more protrusive cells and decreased tissue specificity of the morphotype distribution. Overall, this work establishes a framework for a statistically robust study of cancer cell plasticity in diverse tissue microenvironments.

Melanoma cell plasticity poses diagnostic challenges: a case series.

Phenotype switching is an emerging concept in melanoma research and deals with the cancer cell plasticity. In this paper, we present five cases of patients with metastatic malignant melanoma where the tumor underwent dramatic morphological and immunohistochemical changes thereby mimicking other types of malignancies. The diagnosis of melanoma in all these cases was based on the mutational profile of the tumor assessed by next-generation sequencing compared to the primary lesion or local regional lymph nodes. These cases highlight the importance of thorough diagnostic measures in patients with metastatic melanoma who show progressive disease and where basic pathological assessment shows a diagnostic discrepancy.

Metabolic reprogramming in cholangiocarcinoma.

Metabolic reprogramming is a hallmark of cancer and allows tumour cells to meet the increased energy demands required for rapid proliferation, invasion, and metastasis. Indeed, many tumour cells acquire distinctive metabolic and bioenergetic features that enable them to survive in resource-limited conditions, mainly by harnessing alternative nutrients. Several recent studies have explored the metabolic plasticity of cancer cells with the aim of identifying new druggable targets, while therapeutic strategies to limit the access to nutrients have been successfully applied to the treatment of some tumours. Cholangiocarcinoma (CCA), a highly heterogeneous tumour, is the second most common form of primary liver cancer. It is characterised by resistance to chemotherapy and poor prognosis, with 5-year survival rates of below 20%. Deregulation of metabolic pathways have been described during the onset and progression of CCA. Increased aerobic glycolysis and glutamine anaplerosis provide CCA cells with the ability to generate biosynthetic intermediates. Other metabolic alterations involving carbohydrates, amino acids and lipids have been shown to sustain cancer cell growth and dissemination. In this review, we discuss the complex metabolic rewiring that occurs during CCA development and leads to unique nutrient addiction. The possible role of therapeutic interventions based on metabolic changes is also thoroughly discussed.

A high-throughput drug screen reveals means to differentiate triple-negative breast cancer

Plasticity delineates cancer subtypes with more or less favourable outcomes. In breast cancer, the subtype triple-negative lacks expression of major differentiation markers, e.g., estrogen receptor α (ERα), and its high cellular plasticity results in greater aggressiveness and poorer prognosis than other subtypes. Whether plasticity itself represents a potential vulnerability of cancer cells is not clear. However, we show here that cancer cell plasticity can be exploited to differentiate triple-negative breast cancer (TNBC). Using a high-throughput imaging-based reporter drug screen with 9 501 compounds, we have identified three polo-like kinase 1 (PLK1) inhibitors as major inducers of ERα protein expression and downstream activity in TNBC cells. PLK1 inhibition upregulates a cell differentiation program characterized by increased DNA damage, mitotic arrest, and ultimately cell death. Furthermore, cells surviving PLK1 inhibition have decreased tumorigenic potential, and targeting PLK1 in already established tumours reduces tumour growth both in cell line- and patient-derived xenograft models. In addition, the upregulation of genes upon PLK1 inhibition correlates with their expression in normal breast tissue and with better overall survival in breast cancer patients. Our results indicate that differentiation therapy based on PLK1 inhibition is a potential alternative strategy to treat TNBC.

Therapeutic Targeting of Cancer Stem Cells Prevents Resistance of Colorectal Cancer Cells to MEK Inhibition.

Drug resistance is a leading cause for the failure of cancer treatments. Plasticity of cancer cells to acquire stem cell-like properties enables them to escape drug toxicity through different adaptive mechanisms. Eliminating cancer stem cells (CSCs) can potentially improve treatment outcomes for patients. To determine the role of CSCs in resistance of colorectal cancer cells to targeted therapies and identify treatment strategies, we treated spheroids of BRAFmut and KRASmut colorectal cancer cells with inhibitors of the mitogen-activated protein kinase pathway and studied resistance mechanisms through gene and protein expression analyses. We found that treatments activated several oncogenic pathways and expression of CSC markers CD166 and ALDH1A3. We identified a specific combination treatment using trametinib and mithramycin A to simultaneously inhibit the CSC phenotype and activities of several pathways in cancer cells. This study demonstrates the feasibility of therapeutic targeting of CSCs as a strategy to block tumorigenic activities of cancer cells.

Multiomics characterization implicates PTK7 in ovarian cancer EMT and cell plasticity and offers strategies for therapeutic intervention

Most patients with ovarian cancer (OC) are diagnosed at a late stage when there are very few therapeutic options and a poor prognosis. This is due to the lack of clearly defined underlying mechanisms or an oncogenic addiction that can be targeted pharmacologically, unlike other types of cancer. Here, we identified protein tyrosine kinase 7 (PTK7) as a potential new therapeutic target in OC following a multiomics approach using genetic and pharmacological interventions. We performed proteomics analyses upon PTK7 knockdown in OC cells and identified novel downstream effectors such as synuclein-γ (SNCG), SALL2, and PP1γ, and these findings were corroborated in ex vivo primary samples using PTK7 monoclonal antibody cofetuzumab. Our phosphoproteomics analyses demonstrated that PTK7 modulates cell adhesion and Rho-GTPase signaling to sustain epithelial-mesenchymal transition (EMT) and cell plasticity, which was confirmed by high-content image analysis of 3D models. Furthermore, using high-throughput drug sensitivity testing (525 drugs) we show that targeting PTK7 exhibited synergistic activity with chemotherapeutic agent paclitaxel, CHK1/2 inhibitor prexasertib, and PLK1 inhibitor GSK461364, among others, in OC cells and ex vivo primary samples. Taken together, our study provides unique insight into the function of PTK7, which helps to define its role in mediating aberrant Wnt signaling in ovarian cancer.

Engaging plasticity: Differentiation therapy in solid tumors.

Cancer is a systemic heterogeneous disease that can undergo several rounds of latency and activation. Tumor progression evolves by increasing diversity, adaptation to signals from the microenvironment and escape mechanisms from therapy. These dynamic processes indicate necessity for cell plasticity. Epithelial-mesenchymal transition (EMT) plays a major role in facilitating cell plasticity in solid tumors by inducing dedifferentiation and cell type transitions. These two practices, plasticity and dedifferentiation enhance tumor heterogeneity creating a key challenge in cancer treatment. In this review we will explore cancer cell plasticity and elaborate treatment modalities that aspire to overcome such dynamic processes in solid tumors. We will further discuss the therapeutic potential of utilizing enhanced cell plasticity for differentiation therapy.

Preanalytical Variables in the Analysis of Mitochondrial DNA in Whole Blood and Plasma from Pancreatic Cancer Patients.

Given the crucial role of mitochondria as the main cellular energy provider and its contribution towards tumor growth, chemoresistance, and cancer cell plasticity, mitochondrial DNA (mtDNA) could serve as a relevant biomarker. Thus, the profiling of mtDNA mutations and copy number variations is receiving increasing attention for its possible role in the early diagnosis and monitoring therapies of human cancers. This applies particularly to highly aggressive pancreatic cancer, which is often diagnosed late and is associated with poor prognosis. As current diagnostic procedures are based on imaging, tissue histology, and protein biomarkers with rather low specificity, tumor-derived mtDNA mutations detected from whole blood represents a potential significant leap forward towards early cancer diagnosis. However, for future routine use in clinical settings it is essential that preanalytics related to the characterization of mtDNA in whole blood are thoroughly standardized, controlled, and subject to proper quality assurance, yet this is largely lacking. Therefore, in this study we carried out a comprehensive preanalytical workup comparing different mtDNA extraction methods and testing important preanalytical steps, such as the use of different blood collection tubes, different storage temperatures, length of storage time, and yields in plasma vs. whole blood. To identify analytical and preanalytical differences, all variables were tested in both healthy subjects and pancreatic carcinoma patients. Our results demonstrated a significant difference between cancer patients and healthy subjects for some preanalytical workflows, while other workflows failed to yield statistically significant differences. This underscores the importance of controlling and standardizing preanalytical procedures in the development of clinical assays based on the measurement of mtDNA.

Glycosphingolipids are mediators of cancer plasticity through independent signaling pathways.

The molecular repertoire promoting cancer cell plasticity is not fully elucidated. Here, we propose that glycosphingolipids (GSLs), specifically the globo and ganglio series, correlate and promote the transition between epithelial and mesenchymal cells. The epithelial character of ovarian cancer remains stable throughout disease progression, and spatial glycosphingolipidomics reveals elevated globosides in the tumor compartment compared with the ganglioside-rich stroma. CRISPR-Cas9 knockin mediated truncation of endogenous E-cadherin induces epithelial-to-mesenchymal transition (EMT) and decreases globosides. The transcriptomics analysis identifies the ganglioside-synthesizing enzyme ST8SIA1 to be consistently elevated in mesenchymal-like samples, predicting poor outcome. Subsequent deletion of ST8SIA1 induces epithelial cell features through mTORS2448 phosphorylation, whereas loss of globosides in ΔA4GALT cells, resulting in EMT, is accompanied by increased ERKY202/T204 and AKTS124. The GSL composition dynamics corroborate cancer cell plasticity, and further evidence suggests that mesenchymal cells are maintained through ganglioside-dependent, calcium-mediated mechanisms.

Catulin reporter marks a heterogeneous population of invasive breast cancer cells with some demonstrating plasticity and participating in vascular mimicry

Breast cancer is the most commonly diagnosed cancer in women worldwide. The activation of partial or more complete epithelial–mesenchymal transition in cancer cells enhances acquisition of invasive behaviors and expands their generation of cancer stem cells. Increased by EMT plasticity of tumor cells could promote vascular mimicry, a newly defined pattern of tumor microvascularization by which aggressive tumor cells can form vessel-like structures themselves. VM is strongly associated with a poor prognosis, but biological features of tumor cells that form VM remains unknown. Here we show that catulin is expressed in human BC samples and its expression correlates with the tumor progression. Ablation of catulin in hBC cell lines decreases their invasive potential in the 3D assays. Using a novel catulin promoter based reporter we tracked and characterized the small population of invasive BC cells in xenograft model. RNAseq analysis revealed enrichment in genes important for cellular movement, invasion and interestingly for tumor-vasculature interactions. Analysis of tumors unveiled that catulin reporter marks not only invasive cancer cells but also rare population of plastic, MCAM positive cancer cells that participate in vascular mimicry. Ablation of catulin in the xenograft model revealed deregulation of genes involved in cellular movement, and adhesive properties with striking decrease in CD44 which may impact stemness potential, and plasticity of breast cancer cells. These findings show directly that some plastic tumor cells can change the fate into endothelial-like, expressing MCAM and emphasize the importance of catulin in this process and breast cancer progression.

Highlight: microfluidic devices for cancer metastasis studies

Whilst cancer is the single most researched disease by number of clinical trials, it remains a leading cause of death in middle- to high-income countries, with metastasis as the prime factor in cancer-associated mortality. The complex, multistep process of metastasis, in which cancer cells disseminate from the primary tumour and home to distant sites, is modulated by an extensive set of factors such as matrix properties, cancer cell plasticity, intercellular communication and oxygen tension. However, traditional treatment approaches have been focussed on the removal of the primary and secondary lesions, rather than interference with the metastatic cascade. Microfluidic platforms enable the deconvolution of the processes involved in metastasis by recapitulating key aspects of the tumour microenvironment in a controlled and reproducible fashion. Herein, we review recent developments in microfluidics for metastasis research and explain how these devices offer exceptional potential towards gaining a deeper understanding of this key aspect of malignancy.

The epithelial-to-mesenchymal transition in cancer: pathogenetic features

The epithelial‑to‑mesenchymal transition (EMT) is a cellular biological process, that occurs in a wide range of cells and tissues and is triggered by complex regulatory networks involving transcriptional control with SNAIL, ZEB1, ZEB2, Twist, SLUG, E‑cadherin, vimentin, tumor microenvironment and genetic characteristics. EMT is represented by the multi‑stage development and transformation of cells of the epithelial phenotype into cells that acquire mesenchymal features of various severity. These quasi‑mesenchymal cells are characterized by stemness, tumor heterogeneity, increasing invasiveness, drug resistance and a tendency to distant metastasis, which leads to the proliferation of neoplastic cells, tumor dissemination and initiation of metastasis, which induces the therapy resistance and the oncological recurrence.This review is based on the latest scientific publications about the EMT phenomenon, indexed in PubMed. The aim of the study was to evaluate the biochemical and molecular pathogenetic mechanisms of EMT and the effect of EMT markers on the progression of neoplastic processes and the effectiveness of the treatment. Nowadays the proper EMT scheme that combines all the molecular transformations of sells with quasi‑mesenchymal phenotype doesn’t exist. But analyzing the features of this cellular program, we can find the proper therapy, that could be able to suppress the plasticity of cancer cells, prevent EMT induction by blocking contextual signals, and induce mesenchymal‑epithelial transition. All these aspects will lead to the reduction of the risk of tumor dissemination and the increase of the effectiveness of cancer treatment.

PGC-1α participates in tumor chemoresistance by regulating glucose metabolism and mitochondrial function.

Chemotherapy resistance is the main reason for the failure of cancer treatment. The mechanism of drug resistance is complex and diverse. In recent years, the role of glucose metabolism and mitochondrial function in cancer resistance has gathered considerable interest. The increase in metabolic plasticity of cancer cells' mitochondria and adaptive changes to the mitochondrial function are some of the mechanisms through which cancer cells resist chemotherapy. As a key molecule regulating the mitochondrial function and glucose metabolism, PGC-1α plays an indispensable role in cancer progression. However, the role of PGC-1α in chemotherapy resistance remains controversial. Here, we discuss the role of PGC-1α in glucose metabolism and mitochondrial function and present a comprehensive overview of PGC-1α in chemotherapy resistance.

α-Ketoglutarate-Mediated DNA Demethylation Sustains T-Acute Lymphoblastic Leukemia upon TCA Cycle Targeting.

Simple SummaryA promising anti-cancer strategy is to target the tumor’s dependence on particular nutrients. However, resistance to single-agent treatment is common due to the adaptability of cancer cells. This research seeks to understand how T acute lymphoblastic leukemia (T-ALL) escapes disruption of the tricarboxylic acid (TCA) cycle, a biochemical pathway critical for T-ALL survival. We show that leukemic cells modify their DNA to increase the activity of other pathways to compensate for diminished TCA cycle function. Our findings will help guide the rational selection of therapies to overcome drug resistance.Despite the development of metabolism-based therapy for a variety of malignancies, resistance to single-agent treatment is common due to the metabolic plasticity of cancer cells. Improved understanding of how malignant cells rewire metabolic pathways can guide the rational selection of combination therapy to circumvent drug resistance. Here, we show that human T-ALL cells shift their metabolism from oxidative decarboxylation to reductive carboxylation when the TCA cycle is disrupted. The α-ketoglutarate dehydrogenase complex (KGDHC) in the TCA cycle regulates oxidative decarboxylation by converting α-ketoglutarate (α-KG) to succinyl-CoA, while isocitrate dehydrogenase (IDH) 1 and 2 govern reductive carboxylation. Metabolomics flux analysis of T-ALL reveals enhanced reductive carboxylation upon genetic depletion of the E2 subunit of KGDHC, dihydrolipoamide-succinyl transferase (DLST), mimicking pharmacological inhibition of the complex. Mechanistically, KGDHC dysfunction causes increased demethylation of nuclear DNA by α-KG-dependent dioxygenases (e.g., TET demethylases), leading to increased production of both IDH1 and 2. Consequently, dual pharmacologic inhibition of the TCA cycle and TET demethylases demonstrates additive efficacy in reducing the tumor burden in zebrafish xenografts. These findings provide mechanistic insights into how T-ALL develops resistance to drugs targeting the TCA cycle and therapeutic strategies to overcome this resistance.

Abstract 6291: Integrative single-cell tracking of genome evolution and tumor cell plasticity in small cell lung cancer (SCLC)

Abstract SCLC is the deadliest type of lung cancer, which is mostly diagnosed at late stages and accounts for 15% of pulmonary tumors. Even though chemotherapy is initially effective, SCLC patients relapse quickly with therapy resistant tumors. Genome studies revealed universal loss of TP53 and RB1; recent transcriptional studies categorized SCLC tumors based on the expression of 4 lineage transcription factors (TFs). We aimed to dissect how genomic cues impact transcriptional phenotypes, tumor cell plasticity and the dynamics of tumor and immune cell interactions, to thus decipher molecular mechanisms of phenotypic divergence and therapy resistance in SCLC. We performed genome sequencing and single cell transcriptome profiling on 61 SCLC patient tumors, including primary tumors, metastases and paired relapse tumors acquired throughout therapy. Single cell RNA-seq was performed with the 10x Genomics platform for patient tumors to study cancer cells and the tumor micro-environment (TME)(n=17), and on xenograft models to study tumor cell intrinsic heterogeneity (n=44). Single cell and genome sequencing data were processed with an in-house pipeline. To further validate our findings on the transcriptional level, we performed imaging mass cytometry (IMC) of matched tissue samples to delineate the spatial context of cellular subsets. Single cell transcriptome profiles were determined for 211,446 cells from 61 tumors. Transcriptome profiling at single cell levels revealed co-expression of at least two of the lineage TFs ASCL1, NEUROD1 or POU2F3 for each SCLC tumor. Furthermore, tumor subsets without any expression of the four described TFs were found. Instead of distinct subgroups, our data points to a concerted regulation of a multitude of lineage factors and transcriptional programs in each SCLC tumor. To specifically investigate how underlying genetic alterations affect molecular phenotypes, integrative studies across all patients were performed. This revealed shared transcriptional programs in tumors with MYC family member amplifications; trajectory inference for cases with low and high-level copy gains of MYCN pointed to distinct transcriptional states. We performed multi-regional and longitudinal studies of matched patient cases. We reconstructed genomic patterns of clonal evolution from bulk genome sequencing data, and projected genomic subsets to transcriptional trajectories at single cell level, thus analyzing the effect of genome diversity on the transcriptional landscape. Additionally, tumor intrinsic profiles of heterogeneity were mapped to single cell data of patient tumors to elucidate the effects on the TME, focusing on tumor-immune cell interactions. All together our data provides a first comprehensive framework for the study of underlying genetic alterations that shape the transcriptional landscape and phenotypic plasticity in SCLC. Citation Format: Marcel Schmiel, Roman K. Thomas, Julie George. Integrative single-cell tracking of genome evolution and tumor cell plasticity in small cell lung cancer (SCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6291.

Abstract 1403: ROS metabolism and autophagy as potential targets to improve head and neck cancer treatment

Abstract Introduction: Cancer cells exhibit a high degree of plasticity to adapt the rapidly changing tumor microenvironment (TME), in part by altering cellular metabolic pathways at a faster and more efficient pace than normal cells. Cancer cell plasticity, with genetic and epigenetic alterations, promote the diversity of cancer cells contributing to heterogeneity within the tumor. Head and neck cancer (HNC) is a notable example of this diversity; HNC tumors harbor cells with a wide genetic and metabolic heterogeneity, including cancer stem cells (CSC). Despite current treatment approaches, more than 40% of HNC patients have disease recurrence. Thus, we developed a multimodal approach to effectively prevent the development of radio/drug-resistance. Experimental Procedures: Nuclear-localized mkate2 expressing HNC cell numbers detected for every 6 hours by using IncuCyte S3 instrument. Apoptotic cells detected via NucView 488 Caspase-3 substrate and ROS levels determined using CellROX green simultaneously with cell numbers in the IncuCyte S3 instrument. Synergy scores calculated according to viability in SynergyFinder 2.0 web-application. Results: Our preliminary data profiling of metabolic regulators as radiosensitizer indicate that auranofin (AUR, thioredoxin reductase inhibitor) and buthionine sulfoximine (BSO, γ-glutamylcysteine synthetase inhibitor), given in combination with radiation (RT+AUR+BSO): 1) significantly inhibit proliferation in HNC cell lines, 2) increase ROS accumulation, and 3) reduce the surviving fraction of cells in colony forming assays compared to individual/dual agent applications. Furthermore, we added an autophagy inhibitor, SAR405, in our treatment regimen because of the crosstalk between ROS levels and autophagy. Human (FaDu and UM-SCC-47) and murine (MOC1 and MOC2) HNC cell were treated with +/-AUR+/-BSO+/-SAR405 and high-throughput combinatorial screening of cell numbers obtained over time. The combination of AUR+BSO+SAR405 registered a higher synergy score than the double combinations. Furthermore, as compared to single or double drug applications, the AUR+BSO+SAR405 group had a greater apoptotic cell rate and ROS levels. Conclusion: We present here a high-throughput method to screen multi-drug synergy. Multi-modal approach is important to prevent recurrence by providing a broader effect on heterogenous cancer cells in tumor. Moreover, multi-drug combinations allow usage of lower doses of drugs effectively, hence lowers the treatment-related adverse effects. This approach indicated the possibility of HNC treatment by increasing the ROS levels beyond the containable threshold which is consistent with the recent findings about the alterations in redox metabolism, particularly upregulation in thioredoxin and glutathione pathways, in many cancer types. In vivo experiments are ongoing to evaluate the potential of this combination for clinical studies. Citation Format: Zafer Gurel, Qianyun Luo, Michael S. Luy, Randall J. Kimple. ROS metabolism and autophagy as potential targets to improve head and neck cancer treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1403.

Abstract 2703: Bioinformatics approaches to dissecting androgen receptor activity and cancer stemness during prostate cancer development and progression

Abstract Background: Cancer progression is generally accompanied by loss of differentiation and gain of stemness features. In prostate cancer (PCa), androgen receptor (AR) signaling at the transcription level has been reported to decline in high-grade vs. low-grade tumors. Also, loss of AR expression promotes a stem-like cell phenotype, implicating inverse relationship between AR signaling and stemness in PCa. Here, we aim to understand the dynamic changes in stem-like features and AR signaling activity (AR-A) at the global transcriptomic level, and the relationship between the AR-A and stemness, across the spectrum of PCa development and progression. Methods: We adapted and developed bioinformatic pipelines to assess the degree of cancer stemness (i.e., aggressiveness) and the AR-A during PCa development and progression. And the analysis was performed in published and in-house RNA-seq datasets encompassing normal prostate, primary PCa (TCGA), metastatic castration-resistant PCa (mCRPC), PCa with long-term or neo-adjuvant androgen-deprivation therapy (ADT), and castration-resistant xenografts models. Results: In the normal prostate, significantly higher AR-A and lower stemness were observed in luminal cells compared to basal cells, consistent with the knowledge that luminal cells are differentiated cells regulated by AR signaling whereas the basal cell compartment harbors stem cell activity. In PCa, we have observed that: 1). Surprisingly, both stemness and AR-A are significantly increased in primary PCa compared to benign prostates; 2). In untreated primary PCa, tumor progression is accompanied by significantly reduced AR-A and an increasing trend of stemness; 3). In mCRPC, the AR-A inversely correlates with stemness; 4). Interestingly, while long-term ADT leads to reduced AR-A and increased stemness, short-term ADT during neo-adjuvant therapy (i.e., before the surgery) results in decreased stemness; 5). Our xenograft CRPC models have confirmed the AR-A is significantly reduced in CRPC. Conclusions: PCa development and early growth are accompanied by increased AR-A as well as the stemness. In contrast, the progression of treatment-naïve PCa is accompanied by decreasing AR-A and increasing stemness. In treatment-failed mCRPC, the AR-A shows an inverse correlation with the stemness. Duration of ADT influences the stemness, and stemness functions as a factor of treatment-induced reprogramming. Significance: Developing gene signature scores to assess stemness and AR signaling has allowed us to track the global differentiation status of PCa, and to better understand the cancer cell heterogeneity and plasticity along the course of PCa development, progression and treatment resistance. Our results suggest that increased stemness represents a ‘universal’ feature of PCa progression and aggressiveness and should be therapeutically targeted. Citation Format: Xiaozhuo Liu, Eduardo Cortes Gomez, Yibing Ji, Wanjun Song, Jun Yong, Jianmin Wang, Qiang Hu, Song Liu, Dean Tang. Bioinformatics approaches to dissecting androgen receptor activity and cancer stemness during prostate cancer development and progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2703.

Metabolic plasticity of cancer cells.

A general characteristic of cancer metabolism is the skill to gain the essential nutrients from a relatively poor environment and use them effectively to maintain viability and create new bio-mass. The changes in intracellular and extracellular metabolites that accompany metabolic reprogramming associated with tumor growth subsequently affect gene expression, cell differentiation, and tumor microenvironment. During carcinogenesis, cancer cells face huge selection pressures that force them to constantly optimize dominant metabolic pathways and undergo major metabolic reorganizations. In general, greater flexibility of metabolic pathways increases the ability of tumor cells to satisfy their metabolic needs in a changing environment. In this review, we discuss the metabolic properties of cancer cells and describe the tumor promoting effect of the transformed metabolism. We assume that changes in metabolism are significant enough to facilitate tumorigenesis and may provide interesting targets for cancer therapy.

Abstract 6002: Invasiveness-dependent mechanical plasticity of cancer cells

Abstract Introduction: The capability of living cells to undergo deformations is critical for them to perform different biological functions, such as migration, spreading and endocytosis. Interestingly, recent evidence has also suggested that the mechanical response of cancer cells is intimately related to their pathological state. Physically, a reduced modulus will make it easier for cancer cells to change their morphology when squeezing through tight endothelial cell-cell junctions or pores in the extracellular matrix. However, the deformed cell will fully restore to its original shape if the response is purely elastic or viscoelastic. In this regard, the capability of cells to retain irreversible deformations, and hence effectively “memorize” the characteristics of the physical confinement that they have encountered, could greatly facilitate their subsequent passage through similar barriers, which is a common scenario in tumor cell invasion and metastasis. Here, we developed a method, for the first time to the best of our knowledge, to quantitatively measure the apparent plastic response of tumor cells and examine its correlation with their invasiveness. Materials and Methods: A microfluidic device was designed to deform the cell and then extract its viscoelastic and plastic characteristics from its shape recovery. The chip was casted by molding of silicon wafer which was fabricated using photo etching method. During the test, cells were pushed to squeeze through the deformation channel of the chip. Deformations of the cell and its nucleus were monitored under a fluorescent microscope. Two breast cancer cell lines (MDA-MB-231 and MCF-7), one nasopharyngeal cell line (NP69), and one carcinoma counterpart (HONE-1) were used. To verify the correlation of plastic response with cytoskeleton damage, Latrunculin A was added to block F-actin formation. SYTO fluorescent dye was used for live imaging of the cell nucleus. Results: After being deformed in the narrow channel for a few seconds, cells were released free and recovered the deformation. Interestingly, the highly invasive MDA-MB-231 and HONE-1 cells underwent irreversible deformation even after 10 minutes. However, NP69 and the poorly invasive MCF-7 cells fully recovered to the original round shape in a few minutes. But after blocking the F-actin formation with Latrunculin A, MCF-7 cells retained partial plastic strain. The nucleus elongated when the cell deformed, but fully recovered in 5 minutes. The results indicated the irreversible deformation of cells originated from cytoskeleton damage, but not the nucleus deformation. Conclusions: No apparent irreversible deformation was observed in the less invasive cell lines, suggesting that the plastic response of tumor cells might be correlated with their invasiveness. In addition, it was found that the plastic deformation of highly invasive cancer cells is caused by their cytoskeleton damage rather than plasticity of the nucleus. Citation Format: Xingyu Xia, Zishen Yan, William C. Cho, Yuan Lin. Invasiveness-dependent mechanical plasticity of cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6002.