Cancer recurrence and lethality are enabled by enhanced survival and reversible cell cycle arrest of polyaneuploid cells

Aurkin-A, a TPX2-aurora a small molecule inhibitor disrupts Alisertib-induced polyploidy in aggressive diffuse large B cell lymphoma

Chemotherapy induced polyploidy is a mechanism of inherited drug resistance resulting in an aggressive disease course in cancer patients. Alisertib, an Aurora Kinase A (AK-A) ATP site inhibitor, induces cell cycle disruption resulting in polyaneuploidy in Diffuse Large B Cell Lymphoma (DLBCL). Propidium iodide flow cytometry was utilized to quantify alisertib induced polyploidy in U2932 and VAL cell lines. In U2932 cells, 1µM alisertib generated 8n+ polyploidy in 48% of the total cell population after 5 days of treatment. Combination of Aurkin A an AK-A/TPX2 site inhibitor, plus alisertib disrupted alisertib induced polyploidy in a dose-dependent manner with associated increased apoptosis. We generated a stable FUCCI U2932 cell line expressing Geminin-clover (S/G2/M) and cdt1-mKO (G1), to monitor cell cycle progression. Using this system, we identified alisertib induces polyploidy through endomitosis, which was eliminated with Aurkin A treatment. In a VAL mouse xenograft model, we show polyploidy generation in alisertib treated mice versus vehicle control or Aurkin A. Aurkin A plus alisertib significantly reduced polyploidy to vehicle control levels. Our in vitro and in vivo studies show that Aurkin A synergizes with alisertib and significantly decreases the alisertib dose needed to disrupt polyploidy while increasing apoptosis in DLBCL cells.

Oncogenic signaling in the adult Drosophila prostate-like accessory gland leads to activation of a conserved pro-tumorigenic program, in the absence of proliferation

Drosophila models for tumorigenesis and metastasis have revealed conserved mechanisms of signaling that are also involved in mammalian cancer. Many of these models use the proliferating tissues of the larval stages of Drosophila development, when tissues are highly mitotically active, or stem cells are abundant. Fewer Drosophila tumorigenesis models use adult animals to initiate tumor formation when many tissues are largely terminally differentiated and postmitotic. The Drosophila accessory glands are prostate-like tissues and a model for some aspects of prostate tumorigenesis using this tissue has been explored. In this model, oncogenic signaling was induced during the proliferative stage of accessory gland development, raising the question of how oncogenic activity would impact the terminally differentiated and postmitotic adult tissue. Here, we show that oncogenic signaling in the adult Drosophila accessory gland leads to activation of a conserved pro-tumorigenic program, similar to that observed in mitotic larval tissues, but in the absence of proliferation. Oncogenic signaling in the adult postmitotic gland leads to tissue hyperplasia with nuclear anaplasia and aneuploidy through endoreduplication, which increases polyploidy and occasionally results in non-mitotic neoplastic-like extrusions. We compare gene expression changes in our Drosophila model with that of endocycling prostate cancer cells induced by chemotherapy, which potentially mediate tumor recurrence after treatment. Similar signaling pathways are activated in the Drosophila gland and endocycling cancer cells, suggesting the adult accessory glands provide a useful model for aspects of prostate cancer progression that do not involve cellular proliferation.

Cellular Transformation by Human Cytomegalovirus

Epstein-Barr virus (EBV), Kaposi sarcoma human virus (KSHV), human papillomavirus (HPV), hepatitis B and C viruses (HBV, HCV), human T-lymphotropic virus-1 (HTLV-1), and Merkel cell polyomavirus (MCPyV) are the seven human oncoviruses reported so far. While traditionally viewed as a benign virus causing mild symptoms in healthy individuals, human cytomegalovirus (HCMV) has been recently implicated in the pathogenesis of various cancers, spanning a wide range of tissue types and malignancies. This perspective article defines the biological criteria that characterize the oncogenic role of HCMV and based on new findings underlines a critical role for HCMV in cellular transformation and modeling the tumor microenvironment as already reported for the other human oncoviruses.

Polyploidy in Cancer: Causal Mechanisms, Cancer-Specific Consequences, and Emerging Treatments

Drug resistance is the major determinant for metastatic disease and fatalities, across all cancers. Depending on the tissue of origin and the therapeutic course, a variety of biological mechanisms can support and sustain drug resistance. Although genetic mutations and gene silencing through epigenetic mechanisms are major culprits in targeted therapy, drug efflux and polyploidization are more global mechanisms that prevail in a broad range of pathologies, in response to a variety of treatments. There is an unmet need to identify patients at risk for polyploidy, understand the mechanisms underlying polyploidization, and to develop strategies to predict, limit, and reverse polyploidy thus enhancing efficacy of standard-of-care therapy that improve better outcomes. This literature review provides an overview of polyploidy in cancer and offers perspective on patient monitoring and actionable therapy.

Characterization of polyploidy in cancer: Current status and future perspectives

Various cancers frequently exhibit polyploidy, observed in a condition where a cell possesses more than two sets of chromosomes, which is considered a hallmark of the disease. The state of polyploidy often leads to aneuploidy, where cells possess an abnormal number or structure of chromosomes. Recent studies suggest that oncogenes contribute to aneuploidy. This finding significantly underscores its impact on cancer. Cancer cells exposed to certain chemotherapeutic drugs tend to exhibit an increased incidence of polyploidy. This occurrence is strongly associated with several challenges in cancer treatment, including metastasis, resistance to chemotherapy and the recurrence of malignant tumors. Indeed, it poses a significant hurdle to achieve complete tumor eradication and effective cancer therapy. Recently, there has been a growing interest in the field of polyploidy related to cancer for developing effective anti-cancer therapies. Polyploid cancer cells confer both advantages and disadvantages to tumor pathogenicity. This review delineates the diverse characteristics of polyploid cells, elucidates the pivotal role of polyploidy in cancer, and explores the advantages and disadvantages it imparts to cancer cells, along with the current approaches tried in lab settings to target polyploid cells. Additionally, it considers experimental strategies aimed at addressing the outstanding questions within the realm of polyploidy in relation to cancer.

YY2/BUB3 Axis promotes SAC Hyperactivation and Inhibits Colorectal Cancer Progression via Regulating Chromosomal Instability

Spindle assembly checkpoint (SAC) is a crucial safeguard mechanism of mitosis fidelity that ensures equal division of duplicated chromosomes to the two progeny cells. Impaired SAC can lead to chromosomal instability (CIN), a well-recognized hallmark of cancer that facilitates tumor progression; paradoxically, high CIN levels are associated with better therapeutic response and prognosis. However, the mechanism by which CIN determines tumor cell survival and therapeutic response remains poorly understood. Here, using a cross-omics approach, YY2 is identified as a mitotic regulator that promotes SAC activity by activating the transcription of budding uninhibited by benzimidazole 3 (BUB3), a component of SAC. While both conditions induce CIN, a defect in YY2/SAC activity enhances mitosis and tumor growth. Meanwhile, hyperactivation of SAC mediated by YY2/BUB3 triggers a delay in mitosis and suppresses growth. Furthermore, it is revealed that YY2/BUB3-mediated excessive CIN causes higher cell death rates and drug sensitivity, whereas residual tumor cells that survived DNA damage-based therapy have moderate CIN and increased drug resistance. These results provide insights into the role of SAC activity and CIN levels in influencing tumor cell survival and drug response, as well as suggest a novel anti-tumor therapeutic strategy that combines SAC activity modulators and DNA-damage agents.

Polyploidy Promotes Hypertranscription, Apoptosis Resistance, and Ciliogenesis in Cancer Cells and Mesenchymal Stem Cells of Various Origins: Comparative Transcriptome In Silico Study

Mesenchymal stem cells (MSC) attract an increasing amount of attention due to their unique therapeutic properties. Yet, MSC can undergo undesirable genetic and epigenetic changes during their propagation in vitro. In this study, we investigated whether polyploidy can compromise MSC oncological safety and therapeutic properties. For this purpose, we compared the impact of polyploidy on the transcriptome of cancer cells and MSC of various origins (bone marrow, placenta, and heart). First, we identified genes that are consistently ploidy-induced or ploidy-repressed through all comparisons. Then, we selected the master regulators using the protein interaction enrichment analysis (PIEA). The obtained ploidy-related gene signatures were verified using the data gained from polyploid and diploid populations of early cardiomyocytes (CARD) originating from iPSC. The multistep bioinformatic analysis applied to the cancer cells, MSC, and CARD indicated that polyploidy plays a pivotal role in driving the cell into hypertranscription. It was evident from the upregulation of gene modules implicated in housekeeping functions, stemness, unicellularity, DNA repair, and chromatin opening by means of histone acetylation operating via DNA damage associated with the NUA4/TIP60 complex. These features were complemented by the activation of the pathways implicated in centrosome maintenance and ciliogenesis and by the impairment of the pathways related to apoptosis, the circadian clock, and immunity. Overall, our findings suggest that, although polyploidy does not induce oncologic transformation of MSC, it might compromise their therapeutic properties because of global epigenetic changes and alterations in fundamental biological processes. The obtained results can contribute to the development and implementation of approaches enhancing the therapeutic properties of MSC by removing polyploid cells from the cell population.

scRNAseq and High-Throughput Spatial Analysis of Tumor and Normal Microenvironment in Solid Tumors Reveal a Possible Origin of Circulating Tumor Hybrid Cells

Metastatic cancer is a leading cause of death in cancer patients worldwide. While circulating hybrid cells (CHCs) are implicated in metastatic spread, studies documenting their tissue origin remain sparse, with limited candidate approaches using one-two markers. Utilizing high-throughput single-cell and spatial transcriptomics, we identified tumor hybrid cells (THCs) co-expressing epithelial and macrophage markers and expressing a distinct transcriptome. Rarely, normal tissue showed these cells (NHCs), but their transcriptome was easily distinguishable from THCs. THCs with unique transcriptomes were observed in breast and colon cancers, suggesting this to be a generalizable phenomenon across cancer types. This study establishes a framework for HC identification in large datasets, providing compelling evidence for their tissue residence and offering comprehensive transcriptomic characterization. Furthermore, it sheds light on their differential function and identifies pathways that could explain their newly acquired invasive capabilities. THCs should be considered as potential therapeutic targets.

The antagonistic relationship between apoptosis and polyploidy in development and cancer

One of the important functions of regulated cell death is to prevent cells from inappropriately acquiring extra copies of their genome, a state known as polyploidy. Apoptosis is the primary cell death mechanism that prevents polyploidy, and defects in this apoptotic response can result in polyploid cells whose subsequent error-prone chromosome segregation are a major contributor to genome instability and cancer progression. Conversely, some cells actively repress apoptosis to become polyploid as part of normal development or regeneration. Thus, although apoptosis prevents polyploidy, the polyploid state can actively repress apoptosis. In this review, we discuss progress in understanding the antagonistic relationship between apoptosis and polyploidy in development and cancer. Despite recent advances, a key conclusion is that much remains unknown about the mechanisms that link apoptosis to polyploid cell cycles. We suggest that drawing parallels between the regulation of apoptosis in development and cancer could help to fill this knowledge gap and lead to more effective therapies.

A combinatorial genetic strategy for exploring complex genotype-phenotype associations in cancer

Available genetically defined cancer models are limited in genotypic and phenotypic complexity and underrepresent the heterogeneity of human cancer. Here, we describe a combinatorial genetic strategy applied to an organoid transformation assay to rapidly generate diverse, clinically relevant bladder and prostate cancer models. Importantly, the clonal architecture of the resultant tumors can be resolved using single-cell or spatially resolved next-generation sequencing to uncover polygenic drivers of cancer phenotypes.

NOTCH localizes to mitochondria through the TBC1D15-FIS1 interaction and is stabilized via blockade of E3 ligase and CDK8 recruitment to reprogram tumor-initiating cells

The P53-destabilizing TBC1D15-NOTCH protein interaction promotes self-renewal of tumor-initiating stem-like cells (TICs); however, the mechanisms governing the regulation of this pathway have not been fully elucidated. Here, we show that TBC1D15 stabilizes NOTCH and c-JUN through blockade of E3 ligase and CDK8 recruitment to phosphodegron sequences. Chromatin immunoprecipitation (ChIP-seq) analysis was performed to determine whether TBC1D15-dependent NOTCH1 binding occurs in TICs or non-TICs. The TIC population was isolated to evaluate TBC1D15-dependent NOTCH1 stabilization mechanisms. The tumor incidence in hepatocyte-specific triple knockout (Alb::CreERT2;Tbc1d15Flox/Flox;Notch1Flox/Flox;Notch2Flox/Flox;HCV-NS5A) Transgenic (Tg) mice and wild-type mice was compared after being fed an alcohol-containing Western diet (WD) for 12 months. The NOTCH1-TBC1D15-FIS1 interaction resulted in recruitment of mitochondria to the perinuclear region. TBC1D15 bound to full-length NUMB and to NUMB isoform 5, which lacks three Ser phosphorylation sites, and relocalized NUMB5 to mitochondria. TBC1D15 binding to NOTCH1 blocked CDK8- and CDK19-mediated phosphorylation of the NOTCH1 PEST phosphodegron to block FBW7 recruitment to Thr-2512 of NOTCH1. ChIP-seq analysis revealed that TBC1D15 and NOTCH1 regulated the expression of genes involved in mitochondrial metabolism-related pathways required for the maintenance of TICs. TBC1D15 inhibited CDK8-mediated phosphorylation to stabilize NOTCH1 and protect it from degradation The NUMB-binding oncoprotein TBC1D15 rescued NOTCH1 from NUMB-mediated ubiquitin-dependent degradation and recruited NOTCH1 to the mitochondrial outer membrane for the generation and expansion of liver TICs. A NOTCH-TBC1D15 inhibitor was found to inhibit NOTCH-dependent pathways and exhibited potent therapeutic effects in PDX mouse models. This unique targeting of the NOTCH-TBC1D15 interaction not only normalized the perinuclear localization of mitochondria but also promoted potent cytotoxic effects against TICs to eradicate patient-derived xenografts through NOTCH-dependent pathways.

Dormant cancer cells and polyploid giant cancer cells: The roots of cancer recurrence and metastasis

Tumour cell dormancy is critical for metastasis and resistance to chemoradiotherapy. Polyploid giant cancer cells (PGCCs) with giant or multiple nuclei and high DNA content have the properties of cancer stem cell and single PGCCs can individually generate tumours in immunodeficient mice. PGCCs represent a dormant form of cancer cells that survive harsh tumour conditions and contribute to tumour recurrence. Hypoxic mimics, chemotherapeutics, radiation and cytotoxic traditional Chinese medicines can induce PGCCs formation through endoreduplication and/or cell fusion. After incubation, dormant PGCCs can recover from the treatment and produce daughter cells with strong proliferative, migratory and invasive abilities via asymmetric cell division. Additionally, PGCCs can resist hypoxia or chemical stress and have a distinct protein signature that involves chromatin remodelling and cell cycle regulation. Dormant PGCCs form the cellular basis for therapeutic resistance, metastatic cascade and disease recurrence. This review summarises regulatory mechanisms governing dormant cancer cells entry and exit of dormancy, which may be used by PGCCs, and potential therapeutic strategies for targeting PGCCs.

Modeling stress-induced responses: plasticity in continuous state space and gradual clonal evolution

Mathematical models of cancer and bacterial evolution have generally stemmed from a gene-centric framework, assuming clonal evolution via acquisition of resistance-conferring mutations and selection of their corresponding subpopulations. More recently, the role of phenotypic plasticity has been recognized and models accounting for phenotypic switching between discrete cell states (e.g., epithelial and mesenchymal) have been developed. However, seldom do models incorporate both plasticity and mutationally driven resistance, particularly when the state space is continuous and resistance evolves in a continuous fashion. In this paper, we develop a framework to model plastic and mutational mechanisms of acquiring resistance in a continuous gradual fashion. We use this framework to examine ways in which cancer and bacterial populations can respond to stress and consider implications for therapeutic strategies. Although we primarily discuss our framework in the context of cancer and bacteria, it applies broadly to any system capable of evolving via plasticity and genetic evolution.

Polyploid Cancer Cell Models in Drosophila

Cells with an abnormal number of chromosomes have been found in more than 90% of solid tumors, and among these, polyploidy accounts for about 40%. Polyploidized cells most often have duplicate centrosomes as well as genomes, and thus their mitosis tends to promote merotelic spindle attachments and chromosomal instability, which produces a variety of aneuploid daughter cells. Polyploid cells have been found highly resistant to various stress and anticancer therapies, such as radiation and mitogenic inhibitors. In other words, common cancer therapies kill proliferative diploid cells, which make up the majority of cancer tissues, while polyploid cells, which lurk in smaller numbers, may survive. The surviving polyploid cells, prompted by acute environmental changes, begin to mitose with chromosomal instability, leading to an explosion of genetic heterogeneity and a concomitant cell competition and adaptive evolution. The result is a recurrence of the cancer during which the tenacious cells that survived treatment express malignant traits. Although the presence of polyploid cells in cancer tissues has been observed for more than 150 years, the function and exact role of these cells in cancer progression has remained elusive. For this reason, there is currently no effective therapeutic treatment directed against polyploid cells. This is due in part to the lack of suitable experimental models, but recently several models have become available to study polyploid cells in vivo. We propose that the experimental models in Drosophila, for which genetic techniques are highly developed, could be very useful in deciphering mechanisms of polyploidy and its role in cancer progression.

A mathematical investigation of polyaneuploid cancer cell memory and cross-resistance in state-structured cancer populations

The polyaneuploid cancer cell (PACC) state promotes cancer lethality by contributing to survival in extreme conditions and metastasis. Recent experimental evidence suggests that post-therapy PACC-derived recurrent populations display cross-resistance to classes of therapies with independent mechanisms of action. We hypothesize that this can occur through PACC memory, whereby cancer cells that have undergone a polyaneuploid transition (PAT) reenter the PACC state more quickly or have higher levels of innate resistance. In this paper, we build on our prior mathematical models of the eco-evolutionary dynamics of cells in the 2N+ and PACC states to investigate these two hypotheses. We show that although an increase in innate resistance is more effective at promoting cross-resistance, this trend can also be produced via PACC memory. We also find that resensitization of cells that acquire increased innate resistance through the PAT have a considerable impact on eco-evolutionary dynamics and extinction probabilities. This study, though theoretical in nature, can help inspire future experimentation to tease apart hypotheses surrounding how cross-resistance in structured cancer populations arises.

The diapause-like colorectal cancer cells induced by SMC4 attenuation are characterized by low proliferation and chemotherapy insensitivity

In response to adverse environmental conditions, embryonic development may reversibly cease, a process termed diapause. Recent reports connect this phenomenon with the non-genetic responses of tumors to chemotherapy, but the mechanisms involved are poorly understood. Here, we establish a multifarious role for SMC4 in the switching of colorectal cancer cells to a diapause-like state. SMC4 attenuation promotes the expression of three investment phase glycolysis enzymes increasing lactate production while also suppressing PGAM1. Resultant high lactate levels increase ABC transporter expression via histone lactylation, rendering tumor cells insensitive to chemotherapy. SMC4 acts as co-activator of PGAM1 transcription, and the coordinate loss of SMC4 and PGAM1 affects F-actin assembly, inducing cytokinesis failure and polyploidy, thereby inhibiting cell proliferation. These insights into the mechanisms underlying non-genetic chemotherapy resistance may have significant implications for the field, advancing our understanding of aerobic glycolysis functions in tumor and potentially informing future therapeutic strategies.

Cyclers' kinases in cell division: from molecules to cancer therapy

Faithful eucaryotic cell division requires spatio-temporal orchestration of multiple sequential events. To ensure the dynamic nature of these molecular and morphological transitions, a swift modulation of key regulatory pathways is necessary. The molecular process that most certainly fits this description is phosphorylation, the post-translational modification provided by kinases, that is crucial to allowing the progression of the cell cycle and that culminates with the separation of two identical daughter cells. In detail, from the early stages of the interphase to the cytokinesis, each critical step of this process is tightly regulated by multiple families of kinases including the Cyclin-dependent kinases (CDKs), kinases of the Aurora, Polo, Wee1 families, and many others. While cell-cycle-related CDKs control the timing of the different phases, preventing replication machinery errors, the latter modulate the centrosome cycle and the spindle function, avoiding karyotypic abnormalities typical of chromosome instability. Such chromosomal abnormalities may result from replication stress (RS) and chromosome mis-segregation and are considered a hallmark of poor prognosis, therapeutic resistance, and metastasis in cancer patients. Here, we discuss recent advances in the understanding of how different families of kinases concur to govern cell cycle, preventing RS and mitotic infidelity. Additionally, considering the growing number of clinical trials targeting these molecules, we review to what extent and in which tumor context cell-cycle-related kinases inhibitors are worth exploiting as an effective therapeutic strategy.

Chronic oxidative stress adaptation in head and neck cancer cells generates slow-cyclers with decreased tumour growth in vivo

BACKGROUND

Reactive oxygen species (ROS) are implicated in cancer therapy and as drivers of microenvironmental tumour cell adaptations. Medical gas plasma is a multi-ROS generating technology that has been shown effective for palliative tumour control in head and neck cancer (HNC) patients before tumour cells adapted to the oxidative stress and growth regressed fatally.

METHODS

In a bedside-to-bench approach, we sought to explore the oxidative stress adaptation in two human squamous cell carcinoma cell lines. Gas plasma was utilised as a putative therapeutic agent and chronic oxidative stress inducer.

RESULTS

Cellular responses of single and multiple treated cells were compared regarding sensitivity, cellular senescence, redox state and cytokine release. Whole transcriptome analysis revealed a strong correlation of cancer cell adaption with increased interleukin 1 receptor type 2 (IL1R2) expression. Using magnetic resonance imaging, tumour growth and gas plasma treatment responses of wild-type (WT) and repeatedly exposed (RE) A431 cells were further investigated in a xenograft model in vivo. RE cells generated significantly smaller tumours with suppressed inflammatory secretion profiles and increased epidermal growth factor receptor (EGFR) activity showing significantly lower gas plasma sensitivity until day 8.

CONCLUSIONS

Clinically, combination treatments together with cetuximab, an EGFR inhibitor, may overcome acquired oxidative stress resistance in HNC.

Polyploid Giant Cancer Cells Are Frequently Found in the Urine of Prostate Cancer Patients

Prostate cancer is the third cause of cancer-related deaths in men. Its early and reliable diagnosis is still a public health issue, generating many useless prostate biopsies. Prostate cancer cells detected in urine could be the target of a powerful test but they are considered too rare. By using an approach targeting rare cells, we have analyzed urine from 45 patients with prostate cancer and 43 healthy subjects under 50 y.o. We observed a relevant number of giant cells in patients with cancer. Giant cells, named Polyploid Giant Cancer Cells (PGCC), are thought to be involved in tumorigenesis and treatment resistance. We thus performed immune-morphological studies with cancer-related markers such as α-methylacyl-CoA racemase (AMACR), prostate-specific membrane antigen (PSMA), and telomerase reverse transcriptase (TERT) to understand if the giant cells we found are PGCC or other urinary cells. We found PGCC in the urine of 22 patients, including those with early-stage prostate cancer, and one healthy subject. Although these results are preliminary, they provide, for the first time, clinical evidence that prostate cancers release PGCC into the urine. They are expected to stimulate further studies aimed at understanding the role of urinary PGCC and their possible use as a diagnostic tool and therapeutic target.

Cells in the polyaneuploid cancer cell (PACC) state have increased metastatic potential

Although metastasis is the leading cause of cancer deaths, it is quite rare at the cellular level. Only a rare subset of cancer cells (~ 1 in 1.5 billion) can complete the entire metastatic cascade: invasion, intravasation, survival in the circulation, extravasation, and colonization (i.e. are metastasis competent). We propose that cells engaging a Polyaneuploid Cancer Cell (PACC) phenotype are metastasis competent. Cells in the PACC state are enlarged, endocycling (i.e. non-dividing) cells with increased genomic content that form in response to stress. Single-cell tracking using time lapse microscopy reveals that PACC state cells have increased motility. Additionally, cells in the PACC state exhibit increased capacity for environment-sensing and directional migration in chemotactic environments, predicting successful invasion. Magnetic Twisting Cytometry and Atomic Force Microscopy reveal that cells in the PACC state display hyper-elastic properties like increased peripheral deformability and maintained peri-nuclear cortical integrity that predict successful intravasation and extravasation. Furthermore, four orthogonal methods reveal that cells in the PACC state have increased expression of vimentin, a hyper-elastic biomolecule known to modulate biomechanical properties and induce mesenchymal-like motility. Taken together, these data indicate that cells in the PACC state have increased metastatic potential and are worthy of further in vivo analysis.

Nuclear morphology predicts cell survival to cisplatin chemotherapy

The emergence of chemotherapy resistance drives cancer lethality in cancer patients, with treatment initially reducing overall tumor burden followed by resistant recurrent disease. While molecular mechanisms underlying resistance phenotypes have been explored, less is known about the cell biological characteristics of cancer cells that survive to eventually seed the recurrence. To identify the unique phenotypic characteristics associated with survival upon chemotherapy exposure, we characterized nuclear morphology and function as prostate cancer cells recovered following cisplatin treatment. Cells that survived in the days and weeks after treatment and resisted therapy-induced cell death showed increasing cell size and nuclear size, enabled by continuous endocycling resulting in repeated whole genome doubling. We further found that cells that survive after therapy release were predominantly mononucleated and likely employ more efficient DNA damage repair. Finally, we show that surviving cancer cells exhibit a distinct nucleolar phenotype and increased rRNA levels. These data support a paradigm where soon after therapy release, the treated population mostly contains cells with a high level of widespread and catastrophic DNA damage that leads to apoptosis, while the minority of cells that have successful DDR are more likely to access a pro-survival state. These findings are consistent with accession of the polyaneuploid cancer cell (PACC) state, a recently described mechanism of therapy resistance and tumor recurrence. Our findings demonstrate the fate of cancer cells following cisplatin treatment and define key cell phenotypic characteristics of the PACC state. This work is essential for understanding and, ultimately, targeting cancer resistance and recurrence.

Combinatorial genetic strategy accelerates the discovery of cancer genotype-phenotype associations

Available genetically-defined cancer models are limited in genotypic and phenotypic complexity and underrepresent the heterogeneity of human cancer. Herein, we describe a combinatorial genetic strategy applied to an organoid transformation assay to rapidly generate diverse, clinically relevant bladder and prostate cancer models. Importantly, the clonal architecture of the resultant tumors can be resolved using single-cell or spatially resolved next-generation sequencing to uncover polygenic drivers of cancer phenotypes.

Long-Term Transcriptomic Changes and Cardiomyocyte Hyperpolyploidy after Lactose Intolerance in Neonatal Rats

Many cardiovascular diseases originate from growth retardation, inflammation, and malnutrition during early postnatal development. The nature of this phenomenon is not completely understood. Here we aimed to verify the hypothesis that systemic inflammation triggered by neonatal lactose intolerance (NLI) may exert long-term pathologic effects on cardiac developmental programs and cardiomyocyte transcriptome regulation. Using the rat model of NLI triggered by lactase overloading with lactose and the methods of cytophotometry, image analysis, and mRNA-seq, we evaluated cardiomyocyte ploidy, signs of DNA damage, and NLI-associated long-term transcriptomic changes of genes and gene modules that differed qualitatively (i.e., were switched on or switched off) in the experiment vs. the control. Our data indicated that NLI triggers the long-term animal growth retardation, cardiomyocyte hyperpolyploidy, and extensive transcriptomic rearrangements. Many of these rearrangements are known as manifestations of heart pathologies, including DNA and telomere instability, inflammation, fibrosis, and reactivation of fetal gene program. Moreover, bioinformatic analysis identified possible causes of these pathologic traits, including the impaired signaling via thyroid hormone, calcium, and glutathione. We also found transcriptomic manifestations of increased cardiomyocyte polyploidy, such as the induction of gene modules related to open chromatin, e.g., "negative regulation of chromosome organization", "transcription" and "ribosome biogenesis". These findings suggest that ploidy-related epigenetic alterations acquired in the neonatal period permanently rewire gene regulatory networks and alter cardiomyocyte transcriptome. Here we provided first evidence indicating that NLI can be an important trigger of developmental programming of adult cardiovascular disease. The obtained results can help to develop preventive strategies for reducing the NLI-associated adverse effects of inflammation on the developing cardiovascular system.

Elevated Methionine Flux Drives Pyroptosis Evasion in Persister Cancer Cells

Induction of cell death represents a primary goal of most anticancer treatments. Despite the efficacy of such approaches, a small population of "persisters" develop evasion strategies to therapy-induced cell death. While previous studies have identified mechanisms of resistance to apoptosis, the mechanisms by which persisters dampen other forms of cell death, such as pyroptosis, remain to be elucidated. Pyroptosis is a form of inflammatory cell death that involves formation of membrane pores, ion gradient imbalance, water inflow, and membrane rupture. Herein, we investigate mechanisms by which cancer persisters resist pyroptosis, survive, then proliferate in the presence of tyrosine kinase inhibitors (TKI). Lung, prostate, and esophageal cancer persister cells remaining after treatments exhibited several hallmarks indicative of pyroptosis resistance. The inflammatory attributes of persisters included chronic activation of inflammasome, STING, and type I interferons. Comprehensive metabolomic characterization uncovered that TKI-induced pyroptotic persisters display high methionine consumption and excessive taurine production. Elevated methionine flux or exogenous taurine preserved plasma membrane integrity via osmolyte-mediated effects. Increased dependency on methionine flux decreased the level of one carbon metabolism intermediate S-(5'-adenosyl)-L-homocysteine, a determinant of cell methylation capacity. The consequent increase in methylation potential induced DNA hypermethylation of genes regulating metal ion balance and intrinsic immune response. This enabled thwarting TKI resistance by using the hypomethylating agent decitabine. In summary, the evolution of resistance to pyroptosis can occur via a stepwise process of physical acclimation and epigenetic changes without existing or recurrent mutations.

SIGNIFICANCE

Methionine enables cancer cells to persist by evading pyroptotic osmotic lysis, which leads to genome-wide hypermethylation that allows persisters to gain proliferative advantages.

Cell polarity opposes Jak/STAT-mediated Escargot activation that drives intratumor heterogeneity in a Drosophila tumor model

In proliferating neoplasms, microenvironment-derived selective pressures promote tumor heterogeneity by imparting diverse capacities for growth, differentiation, and invasion. However, what makes a tumor cell respond to signaling cues differently from a normal cell is not well understood. In the Drosophila ovarian follicle cells, apicobasal-polarity loss induces heterogeneous epithelial multilayering. When exacerbated by oncogenic-Notch expression, this multilayer displays an increased consistency in the occurrence of morphologically distinguishable cells adjacent to the polar follicle cells. Polar cells release the Jak/STAT ligand Unpaired (Upd), in response to which neighboring polarity-deficient cells exhibit a precursor-like transcriptomic state. Among the several regulons active in these cells, we could detect and further validate the expression of Snail family transcription factor Escargot (Esg). We also ascertain a similar relationship between Upd and Esg in normally developing ovaries, where establishment of polarity determines early follicular differentiation. Overall, our results indicate that epithelial-cell polarity acts as a gatekeeper against microenvironmental selective pressures that drive heterogeneity.

Presence of cells in the polyaneuploid cancer cell (PACC) state predicts the risk of recurrence in prostate cancer

BACKGROUND

The nonproliferating polyaneuploid cancer cell (PACC) state is associated with therapeutic resistance in cancer. A subset of cancer cells enters the PACC state by polyploidization and acts as cancer stem cells by undergoing depolyploidization and repopulating the tumor cell population after the therapeutic stress is relieved. Our aim was to systematically assess the presence and importance of this entity in men who underwent radical prostatectomy with curative intent to treat their presumed localized prostate cancer (PCa).

MATERIALS AND METHODS

Men with National Comprehensive Cancer Network intermediate- or high-risk PCa who underwent radical prostatectomy l from 2007 to 2015 and who did not receive neoadjuvant treatment were included. From the cohort of 2159 patients, the analysis focused on a subcohort of 209 patients and 38 cases. Prostate tissue microarrays (TMAs) were prepared from formalin-fixed, paraffin-embedded blocks of the radical prostatectomy specimens. A total of 2807 tissue samples of matched normal/benign and cancer were arrayed in nine TMA blocks. The presence of PACCs and the number of PACCs on each core were noted.

RESULTS

The total number of cells in the PACC state and the total number of cores with PACCs were significantly correlated with increasing Gleason score (p = 0.0004) and increasing Cancer of the Prostate Risk Assessment Postsurgical (CAPRA-S) (p = 0.004), but no other variables. In univariate proportional hazards models of metastasis-free survival, year of surgery, Gleason score (9-10 vs. 7-8), pathology stage, CAPRA-S, total PACCs, and cores positive for PACCs were all statistically significant. The multivariable models with PACCs that gave the best fit included CAPRA-S. Adding either total PACCs or cores positive for PACCs to CAPRA-S both significantly improved model fit compared to CAPRA-S alone.

CONCLUSION

Our findings show that the number of PACCs and the number of cores positive for PACCs are statistically significant prognostic factors for metastasis-free survival, after adjusting for CAPRA-S, in a case-cohort of intermediate- or high-risk men who underwent radical prostatectomy. In addition, despite the small number of men with complete data to evaluate time to metastatic castration-resistant PCa (mCRPC), the total number of PACCs was a statistically significant predictor of mCRPC in univariate analysis and suggested a prognostic effect even after adjusting for CAPRA-S.

Combination Chemotherapy of Multidrug-resistant Early-stage Colon Cancer: Determining Optimal Dose Schedules by High-performance Computer Simulation

The goal of this project was to utilize mechanistic simulation to demonstrate a methodology that could determine drug combination dose schedules and dose intensities that would be most effective in eliminating multidrug resistant cancer cells in early-stage colon cancer. An agent-based model of cell dynamics in human colon crypts was calibrated using measurements of human biopsy specimens. Mutant cancer cells were simulated as cells that were resistant to each of two drugs when the drugs were used separately. The drugs, 5-flurouracil and sulindac, have different mechanisms of action. An artificial neural network was used to generate nearly two hundred thousand two-drug dose schedules. A high-performance computer simulated each dose schedule as a in silico clinical trial and evaluated each dose schedule for its efficiency to cure (eliminate) multidrug resistant cancer cells and its toxicity to the host, as indicated by continued crypt function. Among the dose schedules that were generated, 2430 dose schedules were found to cure all multidrug resistant mutants in each of the 50 simulated trials and retained colon crypt function. One dose schedule was optimal; it eliminated multidrug resistant cancer cells with the minimum toxicity and had a time schedule that would be practical for implementation in the clinic. These results demonstrate a procedure to identify which combination drug dose schedules could be most effective in eliminating drug resistant cancer cells. This was accomplished using a calibrated agent-based model of a human tissue, and a high-performance computer simulation of clinical trials.

Cancer Cell De-Differentiation: Plasticity-Driven Stratagem For Tumor Metastasis and Recurrence

Tumor recurrence is a colossal challenge in clinical oncology. This multifactorial problem is attributed to the emergence of additional genetic mutations and the presence of dormant cancer cells. However, the plasticity of non-stem cancer cells and the acquisition of cancer stem cell (CSC) functionality is another contributing factor to tumor recurrence. Herein, I focus attention on the mechanisms that fuel cancer cell de-differentiation and the interplay between intra-cellular regulators and tumor microenvironment (TME) landscape that promotes cancer cell stemness. Our understanding of the mechanisms underlying tumor cell de-differentiation is crucial for developing innovative therapeutic strategies that prevent cancer from ever recurring.

The Nuclear-to-Cytoplasmic Ratio: Coupling DNA Content to Cell Size, Cell Cycle, and Biosynthetic Capacity

Though cell size varies between different cells and across species, the nuclear-to-cytoplasmic (N/C) ratio is largely maintained across species and within cell types. A cell maintains a relatively constant N/C ratio by coupling DNA content, nuclear size, and cell size. We explore how cells couple cell division and growth to DNA content. In some cases, cells use DNA as a molecular yardstick to control the availability of cell cycle regulators. In other cases, DNA sets a limit for biosynthetic capacity. Developmentally programmed variations in the N/C ratio for a given cell type suggest that a specific N/C ratio is required to respond to given physiological demands. Recent observations connecting decreased N/C ratios with cellular senescence indicate that maintaining the proper N/C ratio is essential for proper cellular functioning. Together, these findings suggest a causative, not simply correlative, role for the N/C ratio in regulating cell growth and cell cycle progression.

The Transcriptome and Proteome Networks of Malignant Tumours Reveal Atavistic Attractors of Polyploidy-Related Asexual Reproduction

The expression of gametogenesis-related (GG) genes and proteins, as well as whole genome duplications (WGD), are the hallmarks of cancer related to poor prognosis. Currently, it is not clear if these hallmarks are random processes associated only with genome instability or are programmatically linked. Our goal was to elucidate this via a thorough bioinformatics analysis of 1474 GG genes in the context of WGD. We examined their association in protein-protein interaction and coexpression networks, and their phylostratigraphic profiles from publicly available patient tumour data. The results show that GG genes are upregulated in most WGD-enriched somatic cancers at the transcriptome level and reveal robust GG gene expression at the protein level, as well as the ability to associate into correlation networks and enrich the reproductive modules. GG gene phylostratigraphy displayed in WGD+ cancers an attractor of early eukaryotic origin for DNA recombination and meiosis, and one relative to oocyte maturation and embryogenesis from early multicellular organisms. The upregulation of cancer-testis genes emerging with mammalian placentation was also associated with WGD. In general, the results suggest the role of polyploidy for soma-germ transition accessing latent cancer attractors in the human genome network, which appear as pre-formed along the whole Evolution of Life.

Case report: Plasmablastic neoplasm with multinucleated giant cells—Analysis of stemness of the neoplastic multinucleated giant cells

Cancer stem cells have the capability of self-renewal and multipotency and are, therefore, associated with tumor heterogeneity, resistance to chemoradiation therapy, and metastasis. The hypothesis that multinucleated giant cells, which often emerge following chemo- and/or radiotherapy, serve as cancer stem cells has not been fully evaluated. Although a previous study demonstrated that these cells functioned as stem cells, only low levels of Yamanaka factors were expressed, contrasting with the high expression seen from their gestated first-generation mononuclear cells. Herein, we report a case of a plasmablastic neoplasm with multinucleated giant cells that were analyzed for stemness to test the above hypothesis. The patient was a male in his 80s who had a plasmablastic neoplasm that was not easily distinguishable as plasmablastic lymphoma versus plasma cell myeloma of plasmablastic type. Lymph node biopsy showed predominant mononuclear cell proliferation with admixed multinucleated giant cells. Immunohistochemistry and in situ hybridization showed that both multinucleated and mononuclear cells had the same profile: CD138(+), light chain restriction of κ>λ, cyclin D1(+), CD68(-), EBER-ISH (+). These results suggested that both cell types were neoplastic. In accordance with the previous study, the multinucleated giant cells showed low expression of Yamanaka factors, which were highly expressed in some of the mononuclear cells. Furthermore, the multinucleated giant cells showed a much lower proliferative activity (Mib1/Ki67 index) than the mononuclear cells. Based on these results, the multinucleated giant cells were compatible with cancer stem cells. This case is expected to expand the knowledge base regarding biology of cancer stem cells.

High-Risk Oncogenic Human Cytomegalovirus

Human cytomegalovirus (HCMV) is a herpesvirus that infects between 40% and 95% of the population worldwide, usually without symptoms. The host immune response keeps the virus in a latent stage, although HCMV can reactivate in an inflammatory context, which could result in sequential lytic/latent viral cycles during the lifetime and thereby participate in HCMV genomic diversity in humans. The high level of HCMV intra-host genomic variability could participate in the oncomodulatory role of HCMV where the virus will favor the development and spread of cancerous cells. Recently, an oncogenic role of HCMV has been highlighted in which the virus will directly transform primary cells; such HCMV strains are named high-risk (HR) HCMV strains. In light of these new findings, this review defines the criteria that characterize HR-HCMV strains and their molecular as well as the phenotypic impact on the infected cell and its tumor microenvironment.

What Are the Reasons for Continuing Failures in Cancer Therapy? Are Misleading/Inappropriate Preclinical Assays to Be Blamed? Might Some Modern Therapies Cause More Harm than Benefit?

Over 50 years of cancer research has resulted in the generation of massive amounts of information, but relatively little progress has been made in the treatment of patients with solid tumors, except for extending their survival for a few months at best. Here, we will briefly discuss some of the reasons for this failure, focusing on the limitations and sometimes misunderstanding of the clinical relevance of preclinical assays that are widely used to identify novel anticancer drugs and treatment strategies (e.g., "synthetic lethality"). These include colony formation, apoptosis (e.g., caspase-3 activation), immunoblotting, and high-content multiwell plate cell-based assays, as well as tumor growth studies in animal models. A major limitation is that such assays are rarely designed to recapitulate the tumor repopulating properties associated with therapy-induced cancer cell dormancy (durable proliferation arrest) reflecting, for example, premature senescence, polyploidy and/or multinucleation. Furthermore, pro-survival properties of apoptotic cancer cells through phoenix rising, failed apoptosis, and/or anastasis (return from the brink of death), as well as cancer immunoediting and the impact of therapeutic agents on interactions between cancer and immune cells are often overlooked in preclinical studies. A brief review of the history of cancer research makes one wonder if modern strategies for treating patients with solid tumors may sometimes cause more harm than benefit.

p53 mutation in normal esophagus promotes multiple stages of carcinogenesis but is constrained by clonal competition

Aging normal human oesophagus accumulates TP53 mutant clones. These are the origin of most oesophageal squamous carcinomas, in which biallelic TP53 disruption is almost universal. However, how p53 mutant clones expand and contribute to cancer development is unclear. Here we show that inducing the p53R245W mutant in single oesophageal progenitor cells in transgenic mice confers a proliferative advantage and clonal expansion but does not disrupt normal epithelial structure. Loss of the remaining p53 allele in mutant cells results in genomically unstable p53R245W/null epithelium with giant polyaneuploid cells and copy number altered clones. In carcinogenesis, p53 mutation does not initiate tumour formation, but tumours developing from areas with p53 mutation and LOH are larger and show extensive chromosomal instability compared to lesions arising in wild type epithelium. We conclude that p53 has distinct functions at different stages of carcinogenesis and that LOH within p53 mutant clones in normal epithelium is a critical step in malignant transformation.

Oncogenic and Stemness Signatures of the High-Risk HCMV Strains in Breast Cancer Progression

Simple Summary

Lately, human cytomegalovirus (HCMV) has been progressively implicated in carcinogenesis alongside its oncomodulatory impact. CMV-Transformed Human mammary epithelial cells (CTH) phenotype might be defined by giant cell cycling, whereby the generation of polyploid giant cancer cells (PGCCs) could expedite the acquisition of malignant phenotypes. Herein, the main study objectives were to assess the transformation potential in vitro and evaluate the obtained cellular phenotype, the genetic and molecular features, and the activation of cellular stemness programs of HCMV strains, B544 and B693, which were previously isolated from triple-negative breast cancer (TNBC) biopsies. The strains’ sensitivity to paclitaxel and ganciclovir combination therapy was evaluated. A unique molecular landscape was unveiled in the tumor microenvironment of TNBC harboring high-risk HCMV. Overall, the explicit oncogenic and stemness signatures highlight HCMV potential in breast cancer progression thus paving the way for targeted therapies and clinical interventions which prolong the overall survival of breast cancer patients.

Abstract

Background: Human cytomegalovirus (HCMV) oncomodulation, molecular mechanisms, and ability to support polyploid giant cancer cells (PGCCs) generation might underscore its contribution to oncogenesis, especially breast cancers. The heterogeneity of strains can be linked to distinct properties influencing the virus-transforming potential, cancer types induced, and patient’s clinical outcomes. Methods: We evaluated the transforming potential in vitro and assessed the acquired cellular phenotype, genetic and molecular features, and stimulation of stemness of HCMV strains, B544 and B693, isolated from EZH2^HighMyc^High triple-negative breast cancer (TNBC) biopsies. Therapeutic response assessment after paclitaxel (PTX) and ganciclovir (GCV) treatment was conducted in addition to the molecular characterization of the tumor microenvironment (TME). Findings: HCMV-B544 and B693 transformed human mammary epithelial cells (HMECs). We detected multinucleated and lipid droplet-filled PGCCs harboring HCMV. Colony formation was detected and Myc was overexpressed in CMV-Transformed-HMECs (CTH cells). CTH-B544 and B693 stimulated stemness and established an epithelial/mesenchymal hybrid state. HCMV-IE1 was detected in CTH long-term cultures indicating a sustained viral replication. Biopsy B693 unveiled a tumor signature predicting a poor prognosis. CTH-B544 cells were shown to be more sensitive to PTX/GCV therapy. Conclusion: The oncogenic and stemness signatures of HCMV strains accentuate the oncogenic potential of HCMV in breast cancer progression thereby leading the way for targeted therapies and innovative clinical interventions that will improve the overall survival of breast cancer patients.

Polyploidy and Myc Proto-Oncogenes Promote Stress Adaptation via Epigenetic Plasticity and Gene Regulatory Network Rewiring

Polyploid cells demonstrate biological plasticity and stress adaptation in evolution; development; and pathologies, including cardiovascular diseases, neurodegeneration, and cancer. The nature of ploidy-related advantages is still not completely understood. Here, we summarize the literature on molecular mechanisms underlying ploidy-related adaptive features. Polyploidy can regulate gene expression via chromatin opening, reawakening ancient evolutionary programs of embryonality. Chromatin opening switches on genes with bivalent chromatin domains that promote adaptation via rapid induction in response to signals of stress or morphogenesis. Therefore, stress-associated polyploidy can activate Myc proto-oncogenes, which further promote chromatin opening. Moreover, Myc proto-oncogenes can trigger polyploidization de novo and accelerate genome accumulation in already polyploid cells. As a result of these cooperative effects, polyploidy can increase the ability of cells to search for adaptive states of cellular programs through gene regulatory network rewiring. This ability is manifested in epigenetic plasticity associated with traits of stemness, unicellularity, flexible energy metabolism, and a complex system of DNA damage protection, combining primitive error-prone unicellular repair pathways, advanced error-free multicellular repair pathways, and DNA damage-buffering ability. These three features can be considered important components of the increased adaptability of polyploid cells. The evidence presented here contribute to the understanding of the nature of stress resistance associated with ploidy and may be useful in the development of new methods for the prevention and treatment of cardiovascular and oncological diseases.

A life history model of the ecological and evolutionary dynamics of polyaneuploid cancer cells

Therapeutic resistance is one of the main reasons for treatment failure in cancer patients. The polyaneuploid cancer cell (PACC) state has been shown to promote resistance by providing a refuge for cancer cells from the effects of therapy and by helping them adapt to a variety of environmental stressors. This state is the result of aneuploid cancer cells undergoing whole genome doubling and skipping mitosis, cytokinesis, or both. In this paper, we create a novel mathematical framework for modeling the eco-evolutionary dynamics of state-structured populations and use this framework to construct a model of cancer populations with an aneuploid and a PACC state. Using in silico simulations, we explore how the PACC state allows cancer cells to (1) survive extreme environmental conditions by exiting the cell cycle after S phase and protecting genomic material and (2) aid in adaptation to environmental stressors by increasing the cancer cell's ability to generate heritable variation (evolvability) through the increase in genomic content that accompanies polyploidization. In doing so, we demonstrate the ability of the PACC state to allow cancer cells to persist under therapy and evolve therapeutic resistance. By eliminating cells in the PACC state through appropriately-timed PACC-targeted therapies, we show how we can prevent the emergence of resistance and promote cancer eradication.

Glycidamide and cis-2-butene-1,4-dial (BDA) as potential carcinogens and promoters of liver cancer - An in vitro study

Acrylamide and furan are environmental and food contaminants that are metabolized by cytochrome P450 2E1 (CYP2E1), giving rise to glycidamide and cis-2-butene-1,4-dial (BDA) metabolites, respectively. Both glycidamide and BDA are electrophilic species that react with nucleophilic groups, being able to introduce mutations in DNA and perform epigenetic remodeling. However, whereas these carcinogens are primarily metabolized in the liver, the carcinogenic potential of acrylamide and furan in this organ is still controversial, based on findings from experimental animal studies. With the ultimate goal of providing further insights into this issue, we explored in vitro, using a hepatocyte cell line and a hepatocellular carcinoma cell line, the putative effect of these metabolites as carcinogens and cancer promoters. Molecular alterations were investigated in cells that survive glycidamide and BDA toxicity. We observed that those cells express CD133 stemness marker, present a high proliferative capacity and display an adjusted expression profile of genes encoding enzymes involved in oxidative stress control, such as GCL-C, GSTP1, GSTA3 and CAT. These molecular changes seem to be underlined, at least in part, by epigenetic remodeling involving histone deacetylases (HDACs). Although more studies are needed, here we present more insights towards the carcinogenic capacity of glycidamide and BDA and also point out their effect in favoring hepatocellular carcinoma progression.

Polyploid giant cancer cells are dependent on cholesterol for progeny formation through amitotic division

Polyploid Giant Cancer Cells (PGCC) are increasingly being recognized as drivers of cancer recurrence. Therapy stress promotes the formation of these cells, which upon stress cessation often successfully generate more aggressive progeny that repopulate the tumor. Therefore, identification of potential PGCC vulnerabilities is key to preventing therapy failure. We have previously demonstrated that PGCC progeny formation depends on the lysosomal enzyme acid ceramidase (ASAH1). In this study, we compared transcriptomes of parental cancer cells and PGCC in the absence or presence of the ASAH1 inhibitor LCL521. Results show that PGCC express less INSIG1, which downregulates cholesterol metabolism and that inhibition of ASAH1 increased HMGCR which is the rate limiting enzyme in cholesterol synthesis. Confocal microscopy revealed that ceramide and cholesterol do not colocalize. Treatment with LCL521 or simvastatin to inhibit ASAH1 or HMGCR, respectively, resulted in accumulation of ceramide at the cell surface of PGCC and prevented PGCC progeny formation. Our results suggest that similarly to inhibition of ASAH1, disruption of cholesterol signaling is a potential strategy to interfere with PGCC progeny formation.

Tumor microenvironment heterogeneity an important mediator of prostate cancer progression and therapeutic resistance

Prostate cancer is characterized by a high degree of heterogeneity, which poses a major challenge to precision therapy and drug development. In this review, we discuss how nongenetic factors contribute to heterogeneity of prostate cancer. We also discuss tumor heterogeneity and phenotypic switching related to anticancer therapies. Lastly, we summarize the challenges targeting the tumor environments, and emphasize that continued exploration of tumor heterogeneity is needed in order to offer a personalized therapy for advanced prostate cancer patients.

Mutation in SF3B1 gene promotes formation of polyploid giant cells in Leukemia cells

Giant cells with polyploidy, termed polyploid giant cells, have been observed during normal growth, development, and pathologic states, such as solid cancer progression and resistance to therapy. Functional studies of polyploidal giant cancer cells (PGCC) provided evidence that they arise when normal diploid cells are stressed, show stem cell-like properties, and give rise to tumors. In the present study, we report in K562 leukemia cell line that introduction of the hotspot K700E mutation in the gene SF3B1 using CRISPR/Cas9 method results in an increased frequency of multinucleated polyploid giant cells resistant to chemotherapeutic agent and serum starvation stress. These giant cells with higher ploidy are distinct from multinucleated megakaryocytes, are proliferative, and are characterized by increased accumulation of mitochondria. PGCC have been previously documented in solid tumors. This is the first report describing PGCCs in a cell line derived from a liquid cancer where increased frequency of PGCCs is linked to a specific genetic event. Since SF3B1 mutations are predominantly seen in MDS and other hematologic malignancies, our current findings will have significant clinical implications.

Interplay between Cell Death and Cell Proliferation Reveals New Strategies for Cancer Therapy

Cell division and cell death are fundamental processes governing growth and development across the tree of life. This relationship represents an evolutionary link between cell cycle and cell death programs that is present in all cells. Cancer is characterized by aberrant regulation of both, leading to unchecked proliferation and replicative immortality. Conventional anti-cancer therapeutic strategies take advantage of the proliferative dependency of cancer yet, in doing so, are triggering apoptosis, a death pathway to which cancer is inherently resistant. A thorough understanding of how therapeutics kill cancer cells is needed to develop novel, more durable treatment strategies. While cancer evolves cell-intrinsic resistance to physiological cell death pathways, there are opportunities for cell cycle agnostic forms of cell death, for example, necroptosis or ferroptosis. Furthermore, cell cycle independent death programs are immunogenic, potentially licensing host immunity for additional antitumor activity. Identifying cell cycle independent vulnerabilities of cancer is critical for developing alternative strategies that can overcome therapeutic resistance.

Autophagy modulating therapeutics inhibit ovarian cancer colony generation by polyploid giant cancer cells (PGCCs)

Background

Genomic instability and chemoresistance can arise in cancer due to a unique form of plasticity: that of polyploid giant cancer cells (PGCCs). These cells form under the stress of chemotherapy and have higher than diploid chromosome content. PGCCs are able to then repopulate tumors through an asymmetric daughter cell budding process. PGCCs have been observed in ovarian cancer histology, including the deadly and common form high-grade serous ovarian carcinoma (HGSC). We previously discovered that drugs which disrupt the cellular recycling process of autophagy are uniquely efficacious in pre-clinical HGSC models. While autophagy induction has been associated with PGCCs, it has never been previously investigated if autophagy modulation interacts with the PGCC life cycle and this form of tumor cell plasticity.

Methods

CAOV3 and OVCAR3 ovarian cancer cell lines were treated with carboplatin or docetaxel to induce PGCC formation. Microscopy was used to characterize and quantify PGCCs formed by chemotherapy. Two clinically available drugs that inhibit autophagy, hydroxychloroquine and nelfinavir, and a clinically available activator of autophagy, rapamycin, were employed to test the effect of these autophagy modulators on PGCC induction and subsequent colony formation from PGCCs. Crystal violet-stained colony formation assays were used to quantify the tumor-repopulating stage of the PGCC life cycle.

Results

Autophagy inhibitors did not prevent PGCC formation in OVCAR3 or CAOV3 cells. Rapamycin did not induce PGCC formation on its own nor did it exacerbate PGCC formation by chemotherapy. However, hydroxychloroquine prevented efficient colony formation in CAOV3 PGCCs induced by carboplatin (27% inhibition) or docetaxel (41% inhibition), as well as in OVCAR3 cells (95% and 77%, respectively). Nelfinavir similarly prevented colony formation in CAOV3 PGCCs induced by carboplatin (64% inhibition) or docetaxel (94% inhibition) as well as in OVCAR3 cells (89% and 80%, respectively). Rapamycin surprisingly also prevented PGCC colony outgrowth (52–84% inhibition).

Conclusions

While the autophagy previously observed to correlate with PGCC formation is unlikely necessary for PGCCs to form, autophagy modulating drugs severely impair the ability of HGSC PGCCs to form colonies. Clinical trials which utilize hydroxychloroquine, nelfinavir, and/or rapamycin after chemotherapy may be of future interest.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09503-6.

Tumors and Cytomegalovirus: An Intimate Interplay

Human cytomegalovirus (HCMV) is a herpesvirus that alternates lytic and latent infection, infecting between 40 and 95% of the population worldwide, usually without symptoms. During its lytic cycle, HCMV can result in fever, asthenia, and, in some cases, can lead to severe symptoms such as hepatitis, pneumonitis, meningitis, retinitis, and severe cytomegalovirus disease, especially in immunocompromised individuals. Usually, the host immune response keeps the virus in a latent stage, although HCMV can reactivate in an inflammatory context, which could result in sequential lytic/latent viral cycles during the lifetime and thereby participate in the HCMV genomic diversity in humans and the high level of HCMV intrahost genomic variability. The oncomodulatory role of HCMV has been reported, where the virus will favor the development and spread of cancerous cells. Recently, an oncogenic role of HCMV has been highlighted in which the virus will directly transform primary cells and might therefore be defined as the eighth human oncovirus. In light of these new findings, it is critical to understand the role of the immune landscape, including the tumor microenvironment present in HCMV-harboring tumors. Finally, the oncomodulatory/oncogenic potential of HCMV could lead to the development of novel adapted therapeutic approaches against HCMV, especially since immunotherapy has revolutionized cancer therapeutic strategies and new therapeutic approaches are actively needed, particularly to fight tumors of poor prognosis.

Polyploidy as a Fundamental Phenomenon in Evolution, Development, Adaptation and Diseases

DNA replication during cell proliferation is 'vertical' copying, which reproduces an initial amount of genetic information. Polyploidy, which results from whole-genome duplication, is a fundamental complement to vertical copying. Both organismal and cell polyploidy can emerge via premature cell cycle exit or via cell-cell fusion, the latter giving rise to polyploid hybrid organisms and epigenetic hybrids of somatic cells. Polyploidy-related increase in biological plasticity, adaptation, and stress resistance manifests in evolution, development, regeneration, aging, oncogenesis, and cardiovascular diseases. Despite the prevalence in nature and importance for medicine, agri- and aquaculture, biological processes and epigenetic mechanisms underlying these fundamental features largely remain unknown. The evolutionarily conserved features of polyploidy include activation of transcription, response to stress, DNA damage and hypoxia, and induction of programs of morphogenesis, unicellularity, and longevity, suggesting that these common features confer adaptive plasticity, viability, and stress resistance to polyploid cells and organisms. By increasing cell viability, polyploidization can provide survival under stressful conditions where diploid cells cannot survive. However, in somatic cells it occurs at the expense of specific function, thus promoting developmental programming of adult cardiovascular diseases and increasing the risk of cancer. Notably, genes arising via evolutionary polyploidization are heavily involved in cancer and other diseases. Ploidy-related changes of gene expression presumably originate from chromatin modifications and the derepression of bivalent genes. The provided evidence elucidates the role of polyploidy in evolution, development, aging, and carcinogenesis, and may contribute to the development of new strategies for promoting regeneration and preventing cardiovascular diseases and cancer.

Single-Cell Transcriptomes Combining with Consecutive Genomics Reveal Clonal Evolution and Gene Regulatory Networks in Relapsed and Refractory Multiple Myeloma

This study attempted to investigate how clonal structure evolves, along with potential regulatory networks, as a result of multiline therapies in relapsed/refractory multiple myeloma (RRMM). Eight whole exome sequencing (WES) and one single cell RNA sequencing (scRNA-seq) were performed in order to assess dynamic genomic changes in temporal consecutive samples of one RRMM patient from the time of diagnosis to death (about 37 months). The 63-year-old female patient who suffered from MM (P1) had disease progression (PD) nine times from July 2017 [newly diagnosed (ND)] to Aug 2020 (death), and the force to drive branching-pattern evolution of malignant PCs was found to be sustained. The mutant-allele tumor heterogeneity (MATH) and tumor mutation burden (TMB) initially exhibited a downward trend, which was then upward throughout the course of the disease. Various somatic single nucleotide variants (SNVs) that had disappeared after the previous treatment were observed to reappear in later stages. Chromosomal instability (CIN) and homologous recombination deficiency (HRD) scores were observed to be increased during periods of all progression, especially in the period of extramedullary plasmacytoma. Finally, in combination with WES and scRNA-seq of P1-PD9 (the nineth PD), the intro-heterogeneity and gene regulatory networks of MM cells were deciphered. As verified by the overall survival of MM patients in the MMRF CoMMpass and GSE24080 datasets, RUNX3 was identified as a potential driver for RRMM.

Microenvironment-mediated cancer dormancy: Insights from metastability theory

Dormancy is an evolutionarily conserved protective mechanism widely observed in nature. A pathological example is found during cancer metastasis, where cancer cells disseminate from the primary tumor, home to secondary organs, and enter a growth-arrested state, which could last for decades. Recent studies have pointed toward the microenvironment being heavily involved in inducing, preserving, or ceasing this dormant state, with a strong focus on identifying specific molecular mechanisms and signaling pathways. Increasing evidence now suggests the existence of an interplay between intracellular as well as extracellular biochemical and mechanical cues in guiding such processes. Despite the inherent complexities associated with dormancy, proliferation, and growth of cancer cells and tumor tissues, viewing these phenomena from a physical perspective allows for a more global description, independent from many details of the systems. Building on the analogies between tissues and fluids and thermodynamic phase separation concepts, we classify a number of proposed mechanisms in terms of a thermodynamic metastability of the tumor with respect to growth. This can be governed by interaction with the microenvironment in the form of adherence (wetting) to a substrate or by mechanical confinement of the surrounding extracellular matrix. By drawing parallels with clinical and experimental data, we advance the notion that the local energy minima, or metastable states, emerging in the tissue droplet growth kinetics can be associated with a dormant state. Despite its simplicity, the provided framework captures several aspects associated with cancer dormancy and tumor growth.

Tipping cancer cells over the edge: the context-dependent cost of high ploidy

Tetraploidy is an aneuploidy-permissive condition that can fuel tumorgenesis. The tip-over hypothesis of cytotoxic therapy-sensitivity proposes that therapy is effective if it pushes a cell's aneuploidy above a viable tipping point. But elevated aneuploidy alone may not account for this tipping point. Tissue micro-environments (TMEs) that lack sufficient resources to support tetraploid cells can explain the fitness cost of aneuploidy. Raw materials needed to generate deoxynucleotides, the building blocks of DNA, are candidate rate-limiting factors for the evolution of high-ploidy cancer cells. Understanding the resource cost of high ploidy is key to uncover its therapeutic vulnerabilities across tissue sites with versatile energy supplies.

Chemical Genetic Screen in Drosophila Germline Uncovers Small Molecule Drugs That Sensitize Stem Cells to Insult-Induced Apoptosis

Cancer stem cells, in contrast to their more differentiated daughter cells, can endure genotoxic insults, escape apoptosis, and cause tumor recurrence. Understanding how normal adult stem cells survive and go to quiescence may help identify druggable pathways that cancer stem cells have co-opted. In this study, we utilize a genetically tractable model for stem cell survival in the Drosophila gonad to screen drug candidates and probe chemical-genetic interactions. Our study employs three levels of small molecule screening: (1) a medium-throughput primary screen in male germline stem cells (GSCs), (2) a secondary screen with irradiation and protein-constrained food in female GSCs, and (3) a tertiary screen in breast cancer organoids in vitro. Herein, we uncover a series of small molecule drug candidates that may sensitize cancer stem cells to apoptosis. Further, we have assessed these small molecules for chemical-genetic interactions in the germline and identified the NF-κB pathway as an essential and druggable pathway in GSC quiescence and viability. Our study demonstrates the power of the Drosophila stem cell niche as a model system for targeted drug discovery.