Cellular Pliancy and the Multistep Process of Tumorigenesis

The epipliancy journey: Tumor initiation at the mercy of identity crisis and epigenetic drift

Cellular pliancy refers to the unique disposition of different stages of cellular differentiation to transform when exposed to specific oncogenic insults. This concept highlights a strong interconnection between cellular identity and tumorigenesis, and implies overcoming of epigenetic barriers defining cellular states. Emerging evidence suggests that the cell-type-specific response to intrinsic and extrinsic stresses is modulated by accessibility to certain areas of the genome. Understanding the interplay between epigenetic mechanisms, cellular differentiation, and oncogenic insults is crucial for deciphering the complex nature of tumorigenesis and developing targeted therapies. Hence, cellular pliancy relies on a dynamic cooperation between the cellular identity and the cellular context through epigenetic control, including the reactivation of cellular mechanisms, such as epithelial-to-mesenchymal transition (EMT). Such mechanisms and pathways confer plasticity to the cell allowing it to adapt to a hostile environment in a context of tumor initiation, thus changing its cellular identity. Indeed, growing evidence suggests that cancer is a disease of cell identity crisis, whereby differentiated cells lose their defined identity and gain progenitor characteristics. The loss of cell fate commitment is a central feature of tumorigenesis and appears to be a prerequisite for neoplastic transformation. In this context, EMT-inducing transcription factors (EMT-TFs) cooperate with mitogenic oncoproteins to foster malignant transformation. The aberrant activation of EMT-TFs plays an active role in tumor initiation by alleviating key oncosuppressive mechanisms and by endowing cancer cells with stem cell-like properties, including the ability to self-renew, thus changing the course of tumorigenesis. This highly dynamic phenotypic change occurs concomitantly to major epigenome reorganization, a key component of cell differentiation and cancer cell plasticity regulation. The concept of pliancy was initially proposed to address a fundamental question in cancer biology: why are some cells more likely to become cancerous in response to specific oncogenic events at particular developmental stages? We propose the concept of epipliancy, whereby a difference in epigenetic configuration leads to malignant transformation following an oncogenic insult. Here, we present recent studies furthering our understanding of how the epigenetic landscape may impact the modulation of cellular pliancy during early stages of cancer initiation.

Aging-Associated Vacuolation of Multi-Ciliated Cells in the Distal Mouse Oviduct Reflects Unique Cell Identity and Luminal Microenvironment

The female reproductive organs present with the earliest aging characteristics, such as a decline in fertility and estrous cyclicity. While age-related changes in the ovary are well documented, it is unclear if any age-associated changes occur in the other female reproductive organs, such as the oviduct/Fallopian tube. At the distal end of aged oviducts in mice, we found vacuolated multi-ciliated cells (MCCs) with a severely apically displaced and deformed nucleus. This phenotype was unique to the distal oviduct epithelium-the infundibulum (INF) and ampulla (AMP). Ovariectomy did not affect the timeline of MCC vacuolation, suggesting little involvement of ovulation and hormonal regulation. MCC vacuolation was induced in hypoxia or hydroxyurea treatments in in vitro organotypic culture of all oviduct regions, not limited to the INF/AMP epithelium. This suggests a high oxygen demand in MCCs, compared to other cell types, and a uniquely stressed INF/AMP epithelial microenvironment in vivo. We found that the blood circulation of INF/AMP depended on the ovarian artery, different from the rest of the oviduct epithelium, and its circulation declined along with ovarian activities. We conclude that a decline in local blood circulation and distinct cellular identity of the INF/AMP epithelium caused age-associated MCC vacuolation, reflecting its mild, chronically stressed microenvironment.

Biotechnological advances in 3D modeling of cancer initiation. Examples from pancreatic cancer research and beyond

In recent years, biofabrication technologies have garnered significant attention within the scientific community for their potential to create advancedin vitrocancer models. While these technologies have been predominantly applied to model advanced stages of cancer, there exists a pressing need to develop pertinent, reproducible, and sensitive 3D models that mimic cancer initiation lesions within their native tissue microenvironment. Such models hold profound relevance for comprehending the intricacies of cancer initiation, to devise novel strategies for early intervention, and/or to conduct sophisticated toxicology assessments of putative carcinogens. Here, we will explain the pivotal factors that must be faithfully recapitulated when constructing these models, with a specific focus on early pancreatic cancer lesions. By synthesizing the current state of research in this field, we will provide insights into recent advances and breakthroughs. Additionally, we will delineate the key technological and biological challenges that necessitate resolution in future endeavors, thereby paving the way for more accurate and insightfulin vitrocancer initiation models.

Developmental Heterogeneity of Rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is a pediatric embryonal solid tumor and the most common pediatric soft tissue sarcoma. The histology and transcriptome of RMS resemble skeletal muscle progenitor cells that have failed to terminally differentiate. Thus, RMS is typically thought to arise from corrupted skeletal muscle progenitor cells during development. However, RMS can occur in body regions devoid of skeletal muscle, suggesting the potential for nonmyogenic cells of origin. Here, we discuss the interplay between RMS driver mutations and cell(s) of origin with an emphasis on driving location specificity. Additionally, we discuss the mechanisms governing RMS transformation events and tumor heterogeneity through the lens of transcriptional networks and epigenetic control. Finally, we reimagine Waddington's developmental landscape to include a plane of transformation connecting distinct lineage landscapes to more accurately reflect the phenomena observed in pediatric cancers.

Lessons Learned from Cancer Metabolism for Physiology and Disease

Tumor cells divide rapidly and dramatically alter their metabolism to meet biosynthetic and bioenergetic needs. Through studying the aberrant metabolism of cancer cells, other contexts in which metabolism drives cell state transitions become apparent. In this work, we will discuss how principles established by the field of cancer metabolism have led to discoveries in the contexts of physiology and tissue injury, mammalian embryonic development, and virus infection. We present specific examples of findings from each of these fields that have been shaped by the study of cancer metabolism. We also discuss the next important scientific questions facing these subject areas collectively. Altogether, these examples demonstrate that the study of "cancer metabolism" is indeed the study of cell metabolism in the context of a tumor, and undoubtedly discoveries from each of the fields discussed here will continue to build on each other in the future.

Patient-derived tumor organoids: A preclinical platform for personalized cancer therapy

Patient-derived tumor organoids (PDTOs) represent a significant advancement in cancer research and personalized medicine. These organoids, derived from various cancer types, have shown the ability to retain the genetic and molecular characteristics of the original tumors, allowing for the detailed study of tumor biology and drug responses on an individual basis. The success rates of establishing PDTOs vary widely and are influenced by factors such as cancer type, tissue quality, and media composition. Furthermore, the dynamic nature of organoid cultures may also lead to unique molecular characteristics that deviate from the original tumors, affecting their interpretation in clinical settings without the implementation of rigorous validation and establishment of standardized protocols. Recent studies have supported the correlation between PDTOs and the corresponding patient response. Although these studies involved a small number of patients, they promoted the integration of PDTOs in observational and interventional clinical trials to advance translational cancer therapies.

Epigenomic heterogeneity as a source of tumour evolution

In the past decade, remarkable progress in cancer medicine has been achieved by the development of treatments that target DNA sequence variants. However, a purely genetic approach to treatment selection is hampered by the fact that diverse cell states can emerge from the same genotype. In multicellular organisms, cell-state heterogeneity is driven by epigenetic processes that regulate DNA-based functions such as transcription; disruption of these processes is a hallmark of cancer that enables the emergence of defective cell states. Advances in single-cell technologies have unlocked our ability to quantify the epigenomic heterogeneity of tumours and understand its mechanisms, thereby transforming our appreciation of how epigenomic changes drive cancer evolution. This Review explores the idea that epigenomic heterogeneity and plasticity act as a reservoir of cell states and therefore as a source of tumour evolution. Best practices to quantify epigenomic heterogeneity and explore its various causes and consequences are discussed, including epigenomic reprogramming, stochastic changes and lasting memory. The design of new therapeutic approaches to restrict epigenomic heterogeneity, with the long-term objective of limiting cancer development and progression, is also addressed.

Biochemical pharmacology of adenylyl cyclases in cancer

Globally, despite extensive research and pharmacological advancement, cancer remains one of the most common causes of mortality. Understanding the signaling pathways involved in cancer progression is essential for the discovery of new drug targets. The adenylyl cyclase (AC) superfamily comprises glycoproteins that regulate intracellular signaling and convert ATP into cyclic AMP, an important second messenger. The present review highlights the involvement of ACs in cancer progression and suppression, broken down for each specific mammalian AC isoform. The precise mechanisms by which ACs contribute to cancer cell proliferation and invasion are not well understood and are variable among cancer types; however, AC overactivation, along with that of downstream regulators, presents a potential target for novel anticancer therapies. The expression patterns of ACs in numerous cancers are discussed. In addition, we highlight inhibitors of AC-related signaling that are currently under investigation, with a focus on possible anti-cancer strategies. Recent discoveries with small molecules regarding more direct modulation AC activity are also discussed in detail. A more comprehensive understanding of different components in AC-related signaling could potentially lead to the development of novel therapeutic strategies for personalized oncology and might enhance the efficacy of chemoimmunotherapy in the treatment of various cancers.

An Overview of Cancer Biology, Pathophysiological Development and It's Treatment Modalities: Current Challenges of Cancer anti-Angiogenic Therapy

A number of conditions and factors can cause the transformation of normal cells in the body into malignant tissue by changing the normal functions of a wide range of regulatory, apoptotic, and signal transduction pathways. Despite the current deficiency in fully understanding the mechanism of cancer action accurately and clearly, numerous genes and proteins that are causally involved in the initiation, progression, and metastasis of cancer have been identified. But due to the lack of space and the abundance of details on this complex topic, we have emphasized here more recent advances in our understanding of the principles implied tumor cell transformation, development, invasion, angiogenesis, and metastasis. Inhibition of angiogenesis is a significant strategy for the treatment of various solid tumors, that essentially depend on cutting or at least limiting the supply of blood to micro-regions of tumors, leading to pan-hypoxia and pan-necrosis inside solid tumor tissues. Researchers have continued to enhance the efficiency of anti-angiogenic drugs over the past two decades, to identify their potential in the drug interaction, and to discover reasonable interpretations for possible resistance to treatment. In this review, we have discussed an overview of cancer history and recent methods use in cancer therapy, focusing on anti-angiogenic inhibitors targeting angiogenesis formation. Further, this review has explained the molecular mechanism of action of these anti-angiogenic inhibitors in various tumor types and their limitations use. In addition, we described the synergistic mechanisms of immunotherapy and anti-angiogenic therapy and summarizes current clinical trials of these combinations. Many phase III trials found that combining immunotherapy and anti-angiogenic therapy improved survival. Therefore, targeting the source supply of cancer cells to grow and spread with new anti-angiogenic agents in combination with different conventional therapy is a novel method to reduce cancer progression. The aim of this paper is to overview the varying concepts of cancer focusing on mechanisms involved in tumor angiogenesis and provide an overview of the recent trends in anti-angiogenic strategies for cancer therapy.

The role of Atg5 gene in tumorigenesis under autophagy deficiency conditions

Autophagy is a self-recycling machinery to maintain cellular homeostasis by degrading harmful materials in the cell. Autophagy-related gene 5 (Atg5) is required for autophagosome maturation. However, the role of Atg5 in tumorigenesis under autophagy deficient conditions remains unclear. This study focused on the autophagy-independent role of Atg5 and the underlying mechanism in tumorigenesis. We demonstrated that knockout of autophagy-related genes including Atg5, Atg7, Atg9, and p62 in mouse embryonic fibroblast (MEF) cells consistently decreased cell proliferation and motility, implying that autophagy is required to maintain diverse cellular functions. An Atg7 knockout MEF (Atg7-/- MEF) cell line representing deprivation of autophagy function was used to clarify the role of Atg5 transgene in tumorigenesis. We found that Atg5-overexpressed Atg7-/-MEF (clone A) showed increased cell proliferation, colony formation, and migration under autophagy deficient conditions. Accordingly, rescuing the autophagy deficiency of clone A by overexpression of Atg7 gene shifts the role of Atg5 from pro-tumor to anti-tumor status, indicating the dual role of Atg5 in tumorigenesis. Notably, the xenograft mouse model showed that clone A of Atg5-overexpressed Atg7-/- MEF cells induced temporal tumor formation, but could not prolong further tumor growth. Finally, biomechanical analysis disclosed increased Wnt5a secretion and p-JNK expression along with decreased β-catenin expression. In summary, Atg5 functions as a tumor suppressor to protect the cell under normal conditions. In contrast, Atg5 shifts to a pro-tumor status under autophagy deprivation conditions.

Brd4::Nutm1 fusion gene initiates NUT carcinoma in vivo

NUT carcinoma (NC) is an aggressive cancer with no effective treatment. About 70% of NUT carcinoma is associated with chromosome translocation events that lead to the formation of a BRD4::NUTM1 fusion gene. Because the BRD4::NUTM1 gene is unequivocally cytotoxic when ectopically expressed in cell lines, questions remain on whether the fusion gene can initiate NC. Here, we report the first genetically engineered mouse model for NUT carcinoma that recapitulates the human t(15;19) chromosome translocation in mice. We demonstrated that the mouse t(2;17) syntenic chromosome translocation, forming the Brd4::Nutm1 fusion gene, could induce aggressive carcinomas in mice. The tumors present histopathological and molecular features similar to human NC, with enrichment of undifferentiated cells. Similar to the reports of human NC incidence, Brd4::Nutm1 can induce NC from a broad range of tissues with a strong phenotypical variability. The consistent induction of poorly differentiated carcinoma demonstrated a strong reprogramming activity of BRD4::NUTM1. The new mouse model provided a critical preclinical model for NC that will lead to better understanding and therapy development for NC.

Cellular plasticity in reprogramming, rejuvenation and tumorigenesis: a pioneer TF perspective

The multistep process of in vivo reprogramming, mediated by the transcription factors (TFs) Oct4, Sox2, Klf4, and c-Myc (OSKM), holds great promise for the development of rejuvenating and regenerative strategies. However, most of the approaches developed so far are accompanied by a persistent risk of tumorigenicity. Here, we review the groundbreaking effects of in vivo reprogramming with a particular focus on rejuvenation and regeneration. We discuss how the activity of pioneer TFs generates cellular plasticity that may be critical for inducing not only reprogramming and regeneration, but also cancer initiation. Finally, we highlight how a better understanding of the uncoupled control of cellular identity, plasticity, and aging during reprogramming might pave the way to the development of rejuvenating/regenerating strategies in a nontumorigenic manner.

Ribogenesis boosts controlled by HEATR1-MYC interplay promote transition into brain tumour growth

Cell commitment to tumourigenesis and the onset of uncontrolled growth are critical determinants in cancer development but the early events directing tumour initiating cell (TIC) fate remain unclear. We reveal a single-cell transcriptome profile of brain TICs transitioning into tumour growth using the brain tumour (brat) neural stem cell-based Drosophila model. Prominent changes in metabolic and proteostasis-associated processes including ribogenesis are identified. Increased ribogenesis is a known cell adaptation in established tumours. Here we propose that brain TICs boost ribogenesis prior to tumour growth. In brat-deficient TICs, we show that this dramatic change is mediated by upregulated HEAT-Repeat Containing 1 (HEATR1) to promote ribosomal RNA generation, TIC enlargement and onset of overgrowth. High HEATR1 expression correlates with poor glioma patient survival and patient-derived glioblastoma stem cells rely on HEATR1 for enhanced ribogenesis and tumourigenic potential. Finally, we show that HEATR1 binds the master growth regulator MYC, promotes its nucleolar localisation and appears required for MYC-driven ribogenesis, suggesting a mechanism co-opted in ribogenesis reprogramming during early brain TIC development.

Characterization of tumour microenvironment reprogramming reveals invasion in epithelial ovarian carcinoma

BACKGROUND

Patients with epithelial ovarian carcinoma (EOC) are usually diagnosed at an advanced stage with tumour cell invasion. However, identifying the underlying molecular mechanisms and biomarkers of EOC proliferation and invasion remains challenging.

RESULTS

Herein, we explored the relationship between tumour microenvironment (TME) reprogramming and tissue invasion based on single-cell RNA sequencing (scRNA-seq) datasets. Interestingly, hypoxia, oxidative phosphorylation (OXPHOS) and glycolysis, which have biologically active trajectories during epithelial mesenchymal transition (EMT), were positively correlated. Moreover, energy metabolism and anti-apoptotic activity were found to be critical contributors to intratumor heterogeneity. In addition, HMGA1, EGR1 and RUNX1 were found to be critical drivers of the EMT process in EOC. Experimental validation revealed that suppressing EGR1 expression inhibited tumour cell invasion, significantly upregulated the expression of E-cadherin and decreased the expression of N-cadherin. In cell components analysis, cancer-associated fibroblasts (CAFs) were found to significantly contribute to immune infiltration and tumour invasion, and the accumulation of CAFs was associated with poorer patient survival.

CONCLUSION

We revealed the molecular mechanism and biomarkers of tumour invasion and TME reprogramming in EOC, which provides effective targets for the suppression of tumour invasion.

Disruption of lineage integrity as a precursor to breast tumor initiation

Increase in lineage infidelity and/or imbalance is frequently observed around the earliest stage of breast tumor initiation. In response to disruption of homeostasis, differentiated cells can partially lose their identity and gain cellular plasticity, a process involving epigenome landscape remodeling. This increase of cellular plasticity may promote the malignant transformation of breast tumors and fuel their heterogeneity. Here, we review recent studies that have yield insights into important regulators of lineage integrity and mechanisms that trigger mammary epithelial lineage derail, and evaluate their impacts on breast tumor development.

Chi3l1 Is a Modulator of Glioma Stem Cell States and a Therapeutic Target in Glioblastoma

Chitinase 3-like 1 (Chi3l1) is a secreted protein that is highly expressed in glioblastoma. Here, we show that Chi3l1 alters the state of glioma stem cells (GSC) to support tumor growth. Exposure of patient-derived GSCs to Chi3l1 reduced the frequency of CD133+SOX2+ cells and increased the CD44+Chi3l1+ cells. Chi3l1 bound to CD44 and induced phosphorylation and nuclear translocation of β-catenin, Akt, and STAT3. Single-cell RNA sequencing and RNA velocity following incubation of GSCs with Chi3l1 showed significant changes in GSC state dynamics driving GSCs towards a mesenchymal expression profile and reducing transition probabilities towards terminal cellular states. ATAC-seq revealed that Chi3l1 increases accessibility of promoters containing a Myc-associated zinc finger protein (MAZ) transcription factor footprint. Inhibition of MAZ downregulated a set of genes with high expression in cellular clusters that exhibit significant cell state transitions after treatment with Chi3l1, and MAZ deficiency rescued the Chi3L-induced increase of GSC self-renewal. Finally, targeting Chi3l1 in vivo with a blocking antibody inhibited tumor growth and increased the probability of survival. Overall, this work suggests that Chi3l1 interacts with CD44 on the surface of GSCs to induce Akt/β-catenin signaling and MAZ transcriptional activity, which in turn upregulates CD44 expression in a pro-mesenchymal feed-forward loop. The role of Chi3l1 in regulating cellular plasticity confers a targetable vulnerability to glioblastoma.

SIGNIFICANCE

Chi3l1 is a modulator of glioma stem cell states that can be targeted to promote differentiation and suppress growth of glioblastoma.

Regulative Roles of Metabolic Plasticity Caused by Mitochondrial Oxidative Phosphorylation and Glycolysis on the Initiation and Progression of Tumorigenesis

One important feature of tumour development is the regulatory role of metabolic plasticity in maintaining the balance of mitochondrial oxidative phosphorylation and glycolysis in cancer cells. In recent years, the transition and/or function of metabolic phenotypes between mitochondrial oxidative phosphorylation and glycolysis in tumour cells have been extensively studied. In this review, we aimed to elucidate the characteristics of metabolic plasticity (emphasizing their effects, such as immune escape, angiogenesis migration, invasiveness, heterogeneity, adhesion, and phenotypic properties of cancers, among others) on tumour progression, including the initiation and progression phases. Thus, this article provides an overall understanding of the influence of abnormal metabolic remodeling on malignant proliferation and pathophysiological changes in carcinoma.

Glycosylated proteins with abnormal glycosylation changes are potential biomarkers for early diagnosis of breast cancer

Conventional cancer management relies on tumor type and stage for diagnosis and treatment, which leads to recurrence and metastasis and death in young women. Early detection of proteins in the serum aids diagnosis, progression, and clinical outcomes, possibly improving survival rate of breast cancer patients. In this review, we provided an insight into the influence of aberrant glycosylation on breast cancer development and progression. Examined literatures revealed that mechanisms underlying glycosylation moieties alteration could enhance early detection, monitoring, and therapeutic efficacy in breast cancer patients. This would serve as a guide for the development of new serum biomarkers with higher sensitivity and specificity, providing possible serological biomarkers for breast cancer diagnosis, progression, and treatment.

Numb/Parkin-directed mitochondrial fitness governs cancer cell fate via metabolic regulation of histone lactylation

Cell plasticity and neuroendocrine differentiation in prostate and lung adenocarcinomas are one of the major reasons for therapeutic resistance to targeted therapy. Whether and how metabolic changes contribute to this adenocarcinoma-to-neuroendocrine cell fate transition remains largely unclear. Here we show that neuroendocrine prostate or lung cancer cells possess mostly fragmented mitochondria with low membrane potential and rely on glycolysis for energy metabolism. We further show an important role of the cell fate determinant Numb in mitochondrial quality control via binding to Parkin and facilitating Parkin-mediated mitophagy. Deficiency in the Numb/Parkin pathway in prostate or lung adenocarcinomas causes a metabolic reprogramming featured with a significant increase in production of lactate acid, which subsequently leads to an upregulation of histone lactylation and transcription of neuroendocrine-associated genes. Collectively, the Numb/Parkin-directed mitochondrial fitness is a key metabolic switch and a promising therapeutic target on cancer cell plasticity through the regulation of histone lactylation.

Gold nanoparticles as antiangiogenic and antimetastatic agents

Angiogenesis and metastasis are two interdependent cancer hallmarks, the latter of which is the key cause of treatment failure. Thus, establishing effective antiangiogenesis/antimetastasis agents is the final frontier in cancer research. Gold nanoparticles (GNPs) may provide disruptive advancements in this regard due to their intrinsic physical and physiological features. Here, we comprehensively discuss recent potential therapeutical strategies to treat angiogenesis and metastasis and present a critical review on the state-of-the-art in vitro and in vivo evaluations of the antiangiogenic/antimetastatic activity of GNPs. Finally, we provide perspectives on the contribution of GNPs to the advancement of cancer management.

Bcl11b and Atoh8 Coordinate Cellular Plasticity for Reprogramming and Transformation

By dissecting and comparing the transcriptional trajectories and epigenomic traits of reprogramming and transforming cells at the single-cell resolution, Huyghe et al discovered Bcl11b and Atoh8, two key transcription factors controlling cell plasticity during pluripotent reprogramming and oncogenic transformation.

Single-cell dissection of remodeled inflammatory ecosystem in primary and metastatic gallbladder carcinoma

Gallbladder carcinoma (GBC) is the most common biliary tract malignancy with the lowest survival rate, primarily arising from chronic inflammation. To better characterize the progression from inflammation to cancer to metastasis, we performed single-cell RNA sequencing across samples of 6 chronic cholecystitis, 12 treatment-naive GBCs, and 6 matched metastases. Benign epithelial cells from inflamed gallbladders displayed resting, immune-regulating, and gastrointestinal metaplastic phenotypes. A small amount of PLA2G2A⁺ epithelial cells with copy number variation were identified from a histologically benign sample. We validated significant overexpression of PLA2G2A across in situ GBCs, together with increased proliferation and cancer stemness in PLA2G2A-overexpressing GBC cells, indicating an important role for PLA2G2A during early carcinogenesis. Malignant epithelial cells displayed pervasive cancer hallmarks and cellular plasticity, differentiating into metaplastic, inflammatory, and mesenchymal subtypes with distinct transcriptomic, genomic, and prognostic patterns. Chronic cholecystitis led to an adapted microenvironment characterized by MDSC-like macrophages, CD8⁺ T_RM cells, and CCL2⁺ immunity-regulating fibroblasts. By contrast, GBC instigated an aggressive and immunosuppressive microenvironment, featured by tumor-associated macrophages, Treg cells, CD8⁺ T_EX cells, and STMN1⁺ tumor-promoting fibroblasts. Single-cell and bulk RNA-seq profiles consistently showed a more suppressive immune milieu for GBCs with inflammatory epithelial signatures, coupled with strengthened epithelial-immune crosstalk. We further pinpointed a subset of senescence-like fibroblasts (FN1⁺TGM2⁺) preferentially enriched in metastatic lesions, which promoted GBC migration and invasion via their secretory phenotype. Collectively, this study provides comprehensive insights into epithelial and microenvironmental reprogramming throughout cholecystitis-propelled carcinogenesis and metastasis, laying a new foundation for the precision therapy of GBC.

Cancer Prevention for Survivors: Incidence of Second Primary Cancers and Sex Differences-A Population-Based Study from an Italian Cancer Registry

BACKGROUND

The number of cancer survivors continues to increase, thanks to advances in cancer diagnosis and treatment. Unfortunately, the incidence of a second primary cancer (SPC) is also increasing, but limited studies reporting incidence data are available regarding multiple cancers. This study presents our observations on multiple primary malignant cancers, the associations between sites, and the inherent sex differences.

PATIENTS AND METHODS

We report the data, disaggregated by sex, concerning the SPCs that were recorded in the "Registro Tumori Integrato" (RTI) a population-based cancer registry in Sicily, Italy, as observed in the period from 2003 to 2017, in a total population of approximately 2,300,000. SPCs were divided into synchronous and metachronous cancers. The International Classification of Diseases for Oncology, third edition (ICD-O-3), was used for topographical and morphological classifications. Multiple primary cancers with multi-organ primitiveness were selected from the database of the RTI by extracting patients with more than one diagnosis. SPCs had different histology or morphology from the particular cancer that was considered to be the index cancer case. Multicenter or multifocal cancers, or metastases, were excluded. The percentages of cancer by sex and topography, the average age of incidence, and a breakdown by age were computed.

RESULTS

Differences were observed between sexes in terms of incidence and site for SPCs. The most frequent SPC was skin cancer (20% of the SPCs observed). The associations among sites of multiple cancers are reported.

CONCLUSION

There are many gaps in our knowledge of sex differences in cancer. The study of multiple primary cancers could bring more likely opportunities for evaluation of the cancer burden and trends that can be used to identify new research areas by population health programs, as well as for clinical researchers.

Comparative roadmaps of reprogramming and oncogenic transformation identify Bcl11b and Atoh8 as broad regulators of cellular plasticity

Coordinated changes of cellular plasticity and identity are critical for pluripotent reprogramming and oncogenic transformation. However, the sequences of events that orchestrate these intermingled modifications have never been comparatively dissected. Here, we deconvolute the cellular trajectories of reprogramming (via Oct4/Sox2/Klf4/c-Myc) and transformation (via Ras/c-Myc) at the single-cell resolution and reveal how the two processes intersect before they bifurcate. This approach led us to identify the transcription factor Bcl11b as a broad-range regulator of cell fate changes, as well as a pertinent marker to capture early cellular intermediates that emerge simultaneously during reprogramming and transformation. Multiomics characterization of these intermediates unveiled a c-Myc/Atoh8/Sfrp1 regulatory axis that constrains reprogramming, transformation and transdifferentiation. Mechanistically, we found that Atoh8 restrains cellular plasticity, independent of cellular identity, by binding a specific enhancer network. This study provides insights into the partitioned control of cellular plasticity and identity for both regenerative and cancer biology.

Huyghe, Furlan et al. compare pluripotent reprogramming with oncogenic transformation and identify Bcl11b and Atoh8 as regulators of cellular plasticity in both processes, thus offering a unifying theory on the factors constraining cell fate changes.

Fate decisions of breast cancer stem cells in cancer progression

Breast cancer has a marked recurrence and metastatic trait and is one of the most prevalent malignancies affecting women’s health worldwide. Tumor initiation and progression begin after the cell goes from a quiescent to an activated state and requires different mechanisms to act in concert to regulate t a specific set of spectral genes for expression. Cancer stem cells (CSCs) have been proven to initiate and drive tumorigenesis due to their capability of self-renew and differentiate. In addition, CSCs are believed to be capable of causing resistance to anti-tumor drugs, recurrence and metastasis. Therefore, exploring the origin, regulatory mechanisms and ultimate fate decision of CSCs in breast cancer outcomes has far-reaching clinical implications for the development of breast cancer stem cell (BCSC)-targeted therapeutic strategies. In this review, we will highlight the contribution of BCSCs to breast cancer and explore the internal and external factors that regulate the fate of BCSCs.

Particulate Matter (PM10) Promotes Cell Invasion through Epithelial-Mesenchymal Transition (EMT) by TGF-β Activation in A549 Lung Cells

Air pollution presents a major environmental problem, inducing harmful effects on human health. Particulate matter of 10 μm or less in diameter (PM₁₀) is considered an important risk factor in lung carcinogenesis. Epithelial-mesenchymal transition (EMT) is a regulatory program capable of inducing invasion and metastasis in cancer. In this study, we demonstrated that PM₁₀ treatment induced phosphorylation of SMAD2/3 and upregulation of SMAD4. We also reported that PM₁₀ increased the expression and protein levels of TGFB1 (TGF-β), as well as EMT markers SNAI1 (Snail), SNAI2 (Slug), ZEB1 (ZEB1), CDH2 (N-cadherin), ACTA2 (α-SMA), and VIM (vimentin) in the lung A549 cell line. Cell exposed to PM₁₀ also showed a decrease in the expression of CDH1 (E-cadherin). We also demonstrated that expression levels of these EMT markers were reduced when cells are transfected with small interfering RNAs (siRNAs) against TGFB1. Interestingly, phosphorylation of SMAD2/3 and upregulation of SMAD induced by PM₁₀ were not affected by transfection of TGFB1 siRNAs. Finally, cells treated with PM₁₀ exhibited an increase in the capacity of invasiveness because of EMT induction. Our results provide new evidence regarding the effect of PM₁₀ in EMT and the acquisition of an invasive phenotype, a hallmark necessary for lung cancer progression.

Charting oncogenicity of genes and variants across lineages via multiplexed screens in teratomas

Deconstructing tissue-specific effects of genes and variants on proliferation is critical to understanding cellular transformation and systematically selecting cancer therapeutics. This requires scalable methods for multiplexed genetic screens tracking fitness across time, across lineages, and in a suitable niche, since physiological cues influence functional differences. Towards this, we present an approach, coupling single-cell cancer driver screens in teratomas with hit enrichment by serial teratoma reinjection, to simultaneously screen drivers across multiple lineages in vivo. Using this system, we analyzed population shifts and lineage-specific enrichment for 51 cancer associated genes and variants, profiling over 100,000 cells spanning over 20 lineages, across two rounds of serial reinjection. We confirmed that c-MYC alone or combined with myristoylated AKT1 potently drives proliferation in progenitor neural lineages, demonstrating signatures of malignancy. Additionally, mutant MEK1 S218D/S222D provides a proliferative advantage in mesenchymal lineages like fibroblasts. Our method provides a powerful platform for multi-lineage longitudinal study of oncogenesis.

Crosslink between p53 and metastasis: focus on epithelial-mesenchymal transition, cancer stem cell, angiogenesis, autophagy, and anoikis

INTRODUCTION

P53, as a tumor suppressor gene, is believed to be one of the most mutated genes in cancer cells. The mutant forms of this protein often play a tumorigenic role in cancer cells. Recent evidence shows that p53 plays a critical role in the migration, metastasis, and invasion of cancer cells. The present article aims to investigate the molecular mechanism that induces metastasis in cancer cells generated by the mutant P53, and to highlight the compounds targeting mutant-p53 together with their clinical applications.

METHODS

A detailed literature search was conducted to find information about the role of the mutant-p53 in the processes involved in metastasis in various databases.

RESULTS

A growing body of evidence suggests that Mutant-p53 enhances tumor metastasis affecting the Epithelial-mesenchymal transition (EMT) process, cancer stem cells, angiogenesis, autophagy, anoikis, and any other mechanisms regarding metastasis.

CONCLUSIONS

Taken together, targeting mutant-p53 by altering the processes involved in metastasis could be a potential therapeutic strategy in the treatment of metastatic cancer.

Cellular Plasticity: A Route to Senescence Exit and Tumorigenesis

Senescence is a dynamic, multistep program that results in permanent cell cycle arrest and is triggered by developmental or environmental, oncogenic or therapy-induced stress signals. Senescence is considered as a tumor suppressor mechanism that prevents the risk of neoplastic transformation by restricting the proliferation of damaged cells. Cells undergoing senescence sustain important morphological changes, chromatin remodeling and metabolic reprogramming, and secrete pro-inflammatory factors termed senescence-associated secretory phenotype (SASP). SASP activation is required for the clearance of senescent cells by innate immunity. Therefore, escape from senescence and the associated immune editing would be a prerequisite for tumor initiation and progression as well as therapeutic resistance. One of the possible mechanisms for overcoming senescence could be the acquisition of cellular plasticity resulting from the accumulation of genomic alterations and genetic and epigenetic reprogramming. The modified composition of the SASP produced by these reprogrammed cancer cells would create a permissive environment, allowing their immune evasion. Additionally, the SASP produced by cancer cells could enhance the cellular plasticity of neighboring cells, thus hindering their recognition by the immune system. Here, we propose a comprehensive review of the literature, highlighting the role of cellular plasticity in the pro-tumoral activity of senescence in normal cells and in the cancer context.

Oviduct epithelial cells constitute two developmentally distinct lineages that are spatially separated along the distal-proximal axis

Owing to technical advances in single-cell biology, the appreciation of cellular heterogeneity has increased, which has aided our understanding of organ function, homeostasis, and disease progression. The oviduct (also known as the fallopian tube) is the distalmost portion of the female reproductive tract. It is essential for reproduction and the proposed origin of high-grade serous ovarian carcinoma (HGSOC). In mammals, the oviduct is morphologically segmented along the ovary-uterus axis into four evolutionally conserved regions. It is unclear, however, if there is a diversification of epithelial cell characteristics between these regions. In this study, we identify transcriptionally distinct populations of secretory and multiciliated cells restricted to the distal and proximal regions of the oviduct. We demonstrate that distal and proximal populations are distinct lineages specified early in Müllerian duct development and are maintained separately. These results aid our understanding of epithelial development, homeostasis, and initiation of disease from the oviduct.

Nervous System-Systemic Crosstalk in SARS-CoV-2/COVID-19: A Unique Dyshomeostasis Syndrome

SARS-CoV-2 infection is associated with a spectrum of acute neurological syndromes. A subset of these syndromes promotes higher in-hospital mortality than is predicted by traditional parameters defining critical care illness. This suggests that deregulation of components of the central and peripheral nervous systems compromises the interplay with systemic cellular, tissue and organ interfaces to mediate numerous atypical manifestations of COVID-19 through impairments in organismal homeostasis. This unique dyshomeostasis syndrome involves components of the ACE-2/1 lifecycles, renin-angiotensin system regulatory axes, integrated nervous system functional interactions and brain regions differentially sculpted by accelerated evolutionary processes and more primordial homeostatic functions. These biological contingencies suggest a mechanistic blueprint to define long-term neurological sequelae and systemic manifestations such as premature aging phenotypes, including organ fibrosis, tissue degeneration and cancer. Therapeutic initiatives must therefore encompass innovative combinatorial agents, including repurposing FDA-approved drugs targeting components of the autonomic nervous system and recently identified products of SARS-CoV-2-host interactions.

Breast Cancer-Epidemiology, Risk Factors, Classification, Prognostic Markers, and Current Treatment Strategies-An Updated Review

Breast cancer (BC) is the most frequently diagnosed cancer in women worldwide with more than 2 million new cases in 2020. Its incidence and death rates have increased over the last three decades due to the change in risk factor profiles, better cancer registration, and cancer detection. The number of risk factors of BC is significant and includes both the modifiable factors and non-modifiable factors. Currently, about 80% of patients with BC are individuals aged >50. Survival depends on both stage and molecular subtype. Invasive BCs comprise wide spectrum tumors that show a variation concerning their clinical presentation, behavior, and morphology. Based on mRNA gene expression levels, BC can be divided into molecular subtypes (Luminal A, Luminal B, HER2-enriched, and basal-like). The molecular subtypes provide insights into new treatment strategies and patient stratifications that impact the management of BC patients. The eighth edition of TNM classification outlines a new staging system for BC that, in addition to anatomical features, acknowledges biological factors. Treatment of breast cancer is complex and involves a combination of different modalities including surgery, radiotherapy, chemotherapy, hormonal therapy, or biological therapies delivered in diverse sequences.

Putative homeostatic role of cancer driver mutations

Somatic mutations have traditionally been associated with cancer, yet more recently, it was realized that they also appear in nontransformed cells beginning in early life. Remarkably, some of these mutations, commonly viewed as cancer driver mutations, are widely spread among cells of noncancerous tissues, sometimes affecting the majority of the tissue cells. This spreading process intensifies upon aging or exposure to extrinsic insults, such as UV irradiation, inhaling smoke, and inflammatory cues. Whereas classic driver mutations in normal cells are mostly viewed as a first step in the carcinogenesis process, here, we speculate that in certain states, they can play beneficial homeostatic roles while confronting stress and aging tissue repair.

CENP-A overexpression promotes distinct fates in human cells, depending on p53 status

Tumour evolution is driven by both genetic and epigenetic changes. CENP-A, the centromeric histone H3 variant, is an epigenetic mark that directly perturbs genetic stability and chromatin when overexpressed. Although CENP-A overexpression is a common feature of many cancers, how this impacts cell fate and response to therapy remains unclear. Here, we established a tunable system of inducible and reversible CENP-A overexpression combined with a switch in p53 status in human cell lines. Through clonogenic survival assays, single-cell RNA-sequencing and cell trajectory analysis, we uncover the tumour suppressor p53 as a key determinant of how CENP-A impacts cell state, cell identity and therapeutic response. If p53 is functional, CENP-A overexpression promotes senescence and radiosensitivity. Surprisingly, when we inactivate p53, CENP-A overexpression instead promotes epithelial-mesenchymal transition, an essential process in mammalian development but also a precursor for tumour cell invasion and metastasis. Thus, we uncover an unanticipated function of CENP-A overexpression to promote cell fate reprogramming, with important implications for development and tumour evolution.

In vitro Modeling of Embryonal Tumors

A subset of pediatric tumors affects very young children and are thought to arise during fetal life. A common theme is that these embryonal tumors hijack developmental programs, causing a block in differentiation and, as a consequence, unrestricted proliferation. Embryonal tumors, therefore typically maintain an embryonic gene signature not found in their differentiated progeny. Still, the processes underpinning malignant transformation remain largely unknown, which is hampering therapeutic innovation. To gain more insight into these processes, in vitro and in vivo research models are indispensable. However, embryonic development is an extremely dynamic process with continuously changing cellular identities, making it challenging to define cells-of-origin. This is crucial for the development of representative models, as targeting the wrong cell or targeting a cell within an incorrect developmental time window can result in completely different phenotypes. Recent innovations in in vitro cell models may provide more versatile platforms to study embryonal tumors in a scalable manner. In this review, we outline different in vitro models that can be explored to study embryonal tumorigenesis and for therapy development.

Morphologic and molecular classification of lung neuroendocrine neoplasms

Neuroendocrine neoplasms (NENs) of the lung encompass neuroendocrine tumors (NETs) composed of typical (TC) and atypical (AC) carcinoids and full-fledged carcinomas (NECs) inclusive of large cell neuroendocrine carcinoma (LCNEC) and small cell carcinoma (SCLC). NETs and NECs are thought to represent distinct and separate lesions with neither molecular overlap nor common developmental continuum. Two perspectives were addressed regarding the morphologic and molecular classification of lung NENs: (i) a supervised approach by browsing the traditional classification, the relevant gene alterations, and their clinical implications; and (ii) an unsupervised approach, by reappraising neoplasms according to risk factors and natural history of disease to construct an interpretation model relied on biological data. We herein emphasize lights and shadows of the current classification of lung NENs and provide an alternative outlook on these tumors focused on what we currently know about the biological determinants and the natural history of disease.

Synthetic Lethal Activity of Benzophenanthridine Alkaloids From Zanthoxylum coco Against BRCA1-Deficient Cancer Cells

Several plants from South America show strong antitumoral properties based on anti-proliferative and/or pro-apoptotic activities. In this work we aimed to identify selective cytotoxic compounds that target BRCA1-deficient cancer cells by Synthetic Lethality (SL) induction. Using a high-throughput screening technology developed in our laboratory, we analyzed a collection of extracts from 46 native plant species from Argentina using a wide dose-response scheme. A highly selective SL-induction capacity was found in an alkaloidal extract from Zanthoxylum coco (Fam. Rutaceae). Bio-guided fractionation coupled to HPLC led to the identification of active benzophenanthridine alkaloids. The most potent SL activity was found with the compound oxynitidine, which showed a remarkably low relative abundance in the active fractions. Further validation experiments were performed using the commercially available and closely related analog nitidine, which showed SL-induction activity against various BRCA1-deficient cell lines with different genetic backgrounds, even in the nanomolar range. Exploration of the underlying mechanism of action using BRCA1-KO cells revealed AKT and topoisomerases as the potential targets responsible of nitidine-triggered SL-induction. Taken together, our findings expose an unforeseen therapeutic activity of alkaloids from Zanthoxylum-spp. that position them as novel lead molecules for drug discovery.

Breast cancers, mammary stem cells, and cancer stem cells, characteristics, and hypotheses

The cellular heterogeneity of breast cancers still represents a major therapeutic challenge. The latest genomic studies have classified breast cancers in distinct clusters to inform the therapeutic approaches and predict clinical outcomes. The mammary epithelium is composed of luminal and basal cells, and this seemingly hierarchical organization is dependent on various stem cells and progenitors populating the mammary gland. Some cancer cells are conceptually similar to the stem cells as they can self-renew and generate bulk populations of nontumorigenic cells. Two models have been proposed to explain the cell of origin of breast cancer and involve either the reprogramming of differentiated mammary cells or the dysregulation of mammary stem cells or progenitors. Both hypotheses are not exclusive and imply the accumulation of independent mutational events. Cancer stem cells have been isolated from breast tumors and implicated in the development, metastasis, and recurrence of breast cancers. Recent advances in single-cell sequencing help deciphering the clonal evolution within each breast tumor. Still, few clinical trials have been focused on these specific cancer cell populations.

Non-genetic mechanisms of therapeutic resistance in cancer

Therapeutic resistance continues to be an indominable foe in our ambition for curative cancer treatment. Recent insights into the molecular determinants of acquired treatment resistance in the clinical and experimental setting have challenged the widely held view of sequential genetic evolution as the primary cause of resistance and brought into sharp focus a range of non-genetic adaptive mechanisms. Notably, the genetic landscape of the tumour and the non-genetic mechanisms used to escape therapy are frequently linked. Remarkably, whereas some oncogenic mutations allow the cancer cells to rapidly adapt their transcriptional and/or metabolic programme to meet and survive the therapeutic pressure, other oncogenic drivers convey an inherent cellular plasticity to the cancer cell enabling lineage switching and/or the evasion of anticancer immunosurveillance. The prevalence and diverse array of non-genetic resistance mechanisms pose a new challenge to the field that requires innovative strategies to monitor and counteract these adaptive processes. In this Perspective we discuss the key principles of non-genetic therapy resistance in cancer. We provide a perspective on the emerging data from clinical studies and sophisticated cancer models that have studied various non-genetic resistance pathways and highlight promising therapeutic avenues that may be used to negate and/or counteract the non-genetic adaptive pathways.

Type I interferons and related pathways in cell senescence

This review article addresses the largely unanticipated convergence of two landmark discoveries. The first is the discovery of interferons, critical signaling molecules for all aspects of both innate and adaptive immunity, discovered originally by Isaacs and Lindenmann at the National Institute for Medical Research, London, in 1957 (Proceedings of the Royal Society of London. Series B: Biological Sciences, 1957, 147, 258). The second, formerly unrelated discovery, by Leonard Hayflick and Paul Moorhead (Wistar Institute, Philadelphia) is that cultured cells undergo an irreversible but viable growth arrest, termed senescence, after a finite and predictable number of cell divisions (Experimental Cell Research, 1961, 25, 585). This phenomenon was suspected to relate to organismal aging, which was confirmed subsequently (Nature, 2011, 479, 232). Cell senescence has broad‐ranging implications for normal homeostasis, including immunity, and for diverse disease states, including cancer progression and response to therapy (Nature Medicine, 2015, 21, 1424; Cell, 2019, 179, 813; Cell, 2017, 169, 1000; Trends in Cell Biology, 2018, 28, 436; Journal of Cell Biology, 2018, 217, 65). Here, we critically address the bidirectional interplay between interferons (focusing on type I) and cell senescence, with important implications for health and healthspan.

Cell plasticity in cancer: A complex interplay of genetic, epigenetic mechanisms and tumor micro-environment

Cell plasticity, also known as lineage plasticity is defined as the ability of a cell to reprogram and change its phenotype identity. Cell plasticity is context dependent and occurs during the development of an embryo, tissue regeneration, wound healing. However when deregulated and aberrant it also contributes to cancer initiation, progression, metastases and resistance to therapies. Tumors cells exhibit varying forms of cell plasticity in each stage of the disease to evade normal regulation as would have occurred in normal cell division and homeostasis. Current evidence demonstrates complex interplay between the genes, epigenes, tumor microenvironment and the EMT in cell reprogramming and cancer cell plasticity. Herein we present experimental evidence and evolving new developments in cell plasticity in cancer cells. Additionally "Deregulated/aberrant/hijacked cell plasticity" could be considered as an additional hallmark of a cancer. In the future, combining the advances in next generation sequencing and single cell RNA techniques with evolving AI (artificial intelligence) technologies such as deep learning techniques may predict the trajectories of cancer cells and assist in navigating through the complex intricacies of the cancers. A durable, precise, personalized oncologic treatment could be a reality.

Outdoor air pollution and cancer: An overview of the current evidence and public health recommendations

Outdoor air pollution is a major contributor to the burden of disease worldwide. Most of the global population resides in places where air pollution levels, because of emissions from industry, power generation, transportation, and domestic burning, considerably exceed the World Health Organization's health-based air-quality guidelines. Outdoor air pollution poses an urgent worldwide public health challenge because it is ubiquitous and has numerous serious adverse human health effects, including cancer. Currently, there is substantial evidence from studies of humans and experimental animals as well as mechanistic evidence to support a causal link between outdoor (ambient) air pollution, and especially particulate matter (PM) in outdoor air, with lung cancer incidence and mortality. It is estimated that hundreds of thousands of lung cancer deaths annually worldwide are attributable to PM air pollution. Epidemiological evidence on outdoor air pollution and the risk of other types of cancer, such as bladder cancer or breast cancer, is more limited. Outdoor air pollution may also be associated with poorer cancer survival, although further research is needed. This report presents an overview of outdoor air pollutants, sources, and global levels, as well as a description of epidemiological evidence linking outdoor air pollution with cancer incidence and mortality. Biological mechanisms of air pollution-derived carcinogenesis are also described. This report concludes by summarizing public health/policy recommendations, including multilevel interventions aimed at individual, community, and regional scales. Specific roles for medical and health care communities with regard to prevention and advocacy and recommendations for further research are also described.

Temporal patterning in neural progenitors: from Drosophila development to childhood cancers

The developing central nervous system (CNS) is particularly prone to malignant transformation, but the underlying mechanisms remain unresolved. However, periods of tumor susceptibility appear to correlate with windows of increased proliferation, which are often observed during embryonic and fetal stages and reflect stereotypical changes in the proliferative properties of neural progenitors. The temporal mechanisms underlying these proliferation patterns are still unclear in mammals. In Drosophila, two decades of work have revealed a network of sequentially expressed transcription factors and RNA-binding proteins that compose a neural progenitor-intrinsic temporal patterning system. Temporal patterning controls both the identity of the post-mitotic progeny of neural progenitors, according to the order in which they arose, and the proliferative properties of neural progenitors along development. In addition, in Drosophila, temporal patterning delineates early windows of cancer susceptibility and is aberrantly regulated in developmental tumors to govern cellular hierarchy as well as the metabolic and proliferative heterogeneity of tumor cells. Whereas recent studies have shown that similar genetic programs unfold during both fetal development and pediatric brain tumors, I discuss, in this Review, how the concept of temporal patterning that was pioneered in Drosophila could help to understand the mechanisms of initiation and progression of CNS tumors in children.

Twist-mediated PAR1 induction is required for breast cancer progression and metastasis by inhibiting Hippo pathway

Breast cancer is considered to be the most prevalent cancer in women worldwide, and metastasis is the primary cause of death. Protease-activated receptor 1 (PAR1) is a GPCR family member involved in the invasive and metastatic processes of cancer cells. However, the functions and underlying mechanisms of PAR1 in breast cancer remain unclear. In this study, we found that PAR1 is highly expressed in high invasive breast cancer cells, and predicts poor prognosis in ER-negative and high-grade breast cancer patients. Mechanistically, Twist transcriptionally induces PAR1 expression, leading to inhibition of Hippo pathway and activation of YAP/TAZ; Inhibition of PAR1 suppresses YAP/TAZ-induced epithelial-mesenchymal transition (EMT), invasion, migration, cancer stem cell (CSC)-like properties, tumor growth and metastasis of breast cancer cells in vitro and in vivo. These findings suggest that PAR1 acts as a direct transcriptionally target of Twist, can promote EMT, tumorigenicity and metastasis by controlling the Hippo pathway; this may lead to a potential therapeutic target for treating invasive breast cancer.

Comprehensive characterization of claudin-low breast tumors reflects the impact of the cell-of-origin on cancer evolution

Claudin-low breast cancers are aggressive tumors defined by the low expression of key components of cellular junctions, associated with mesenchymal and stemness features. Although they are generally considered as the most primitive breast malignancies, their histogenesis remains elusive. Here we show that this molecular subtype of breast cancers exhibits a significant diversity, comprising three main subgroups that emerge from unique evolutionary processes. Genetic, gene methylation and gene expression analyses reveal that two of the subgroups relate, respectively, to luminal breast cancers and basal-like breast cancers through the activation of an EMT process over the course of tumor progression. The third subgroup is closely related to normal human mammary stem cells. This unique subgroup of breast cancers shows a paucity of genomic aberrations and a low frequency of TP53 mutations, supporting the emerging notion that the intrinsic properties of the cell-of-origin constitute a major determinant of the genetic history of tumorigenesis.

Re-definition of claudin-low as a breast cancer phenotype

The claudin-low breast cancer subtype is defined by gene expression characteristics and encompasses a remarkably diverse range of breast tumors. Here, we investigate genomic, transcriptomic, and clinical features of claudin-low breast tumors. We show that claudin-low is not simply a subtype analogous to the intrinsic subtypes (basal-like, HER2-enriched, luminal A, luminal B and normal-like) as previously portrayed, but is a complex additional phenotype which may permeate breast tumors of various intrinsic subtypes. Claudin-low tumors are distinguished by low genomic instability, mutational burden and proliferation levels, and high levels of immune and stromal cell infiltration. In other aspects, claudin-low tumors reflect characteristics of their intrinsic subtype. Finally, we explore an alternative method for identifying claudin-low tumors and thereby uncover potential weaknesses in the established claudin-low classifier. In sum, these findings elucidate the heterogeneity in claudin-low breast tumors, and substantiate a re-definition of claudin-low as a cancer phenotype.

In breast cancer, the claudin-low breast cancer subtype is remarkably diverse. Here, the authors propose that claudin-low is not a classical intrinsic breast cancer subtype, but rather a complex additional phenotype that can occur across intrinsic subtypes.

Plasticity of Cancer Stem Cell: Origin and Role in Disease Progression and Therapy Resistance

In embryonic development and throughout life, there are some cells can exhibit phenotypic plasticity. Phenotypic plasticity is the ability of cells to differentiate into multiple lineages. In normal development, plasticity is highly regulated whereas cancer cells re-activate this dynamic ability for their own progression. The re-activation of these mechanisms enables cancer cells to acquire a cancer stem cell (CSC) phenotype- a subpopulation of cells with increased ability to survive in a hostile environment and resist therapeutic insults. There are several contributors fuel CSC plasticity in different stages of disease progression such as a complex network of tumour stroma, epidermal microenvironment and different sub-compartments within tumour. These factors play a key role in the transformation of tumour cells from a stable condition to a progressive state. In addition, flexibility in the metabolic state of CSCs helps in disease progression. Moreover, epigenetic changes such as chromatin, DNA methylation could stimulate the phenotypic change of CSCs. Development of resistance to therapy due to highly plastic behaviour of CSCs is a major cause of treatment failure in cancers. However, recent studies explored that plasticity can also expose the weaknesses in CSCs, thereby could be utilized for future therapeutic development. Therefore, in this review, we discuss how cancer cells acquire the plasticity, especially the role of the normal developmental process, tumour microenvironment, and epigenetic changes in the development of plasticity. We further highlight the therapeutic resistance property of CSCs attributed by plasticity. Also, outline some potential therapeutic options against plasticity of CSCs. Graphical Abstract .

HNF-1a promotes pancreatic cancer growth and apoptosis resistance via its target gene PKLR

Pancreatic ductal adenocarcinoma is one of the deadliest malignant tumors, and many genes play important roles in its development. The hepatocyte nuclear factor-1a (HNF-1a) gene encodes HNF-1a, which is a transcriptional activator. HNF-1a regulates the tissue-specific expression of multiple genes, especially in pancreatic islet cells and in the liver. However, the role of the HNF-1a gene in the development of pancreatic cancer is still unclear. Here, we used immunohistochemical staining and real-time PCR to analyze HNF-1a expression in pancreatic cancer tissue. Stable cell lines with HNF-1a knockdown or overexpression were established to analyze the role of HNF-1a in pancreatic cancer cell proliferation and apoptosis by colony formation assay and flow cytometry. We also analyzed the L-type pyruvate kinase (PKLR) promoter sequence to identify the regulatory effect of HNF-1a on PKLR transcription and confirmed the HNF-1a binding site in the PKLR promoter via a chromatin immunoprecipitation assay. HNF-1a was found to be overexpressed in pancreatic cancer and promoted proliferation while inhibiting apoptosis in pancreatic cancer cells. PKLR was identified as the downstream target gene of HNF-1a and binding of HNF-1a at two sites in PKLR (-1931/-1926 and -966/-961) regulated PKLR transcription. In conclusion, HNF-1a is overexpressed in pancreatic cancer, and the transcription factor HNF-1a can promote pancreatic cancer growth and apoptosis resistance via its target gene PKLR.