Tumor cell dormancy

SNAI2 enhances HPV‑negative cervical cancer cell dormancy by modulating u‑PAR expression and the activity of the ERK/p38 signaling pathway in vitro

The prognosis of patients with human papillomavirus (HPV)‑negative cervical cancer is significantly worse than that of patients with HPV‑positive cervical cancer. Understanding the mechanisms of this is crucial for preventing disease evolution. In the present study, the GV367‑snail family transcriptional repressor 2 (SNAI2) lentiviral vector was constructed and transduced into C‑33A cells. Subsequently, the proliferation of tumor cells was detected using the Cell Counting Kit (CCK)‑8 method. Flow cytometry was used to analyze the cell cycle progression of tumor cells. The glucose consumption of tumor cells was detected using an oxidase assay, and the senescence of tumor cells was detected using beta‑galactosidase staining. The gene expression and the activity of p38 and ERK1/2 were detected using reverse transcription‑quantitative PCR and western blotting, respectively. The C‑33A‑SNAI2 cell line was successfully established. Compared with HeLa and C‑33A‑Wild cells, the proliferation and percentage of G0/G1‑phase cells in the C‑33A‑SNAI2 group were decreased, as detected by the CCK‑8 assay (100±0 vs. 239.1±58.3 vs. 39.7±20.1, P<0.01) and flow cytometry (34.0±7.1% vs. 46.2±10.6% vs. 61.3±5.3%, P<0.05). Compared with the HeLa group, the glucose consumption of the C‑33A‑Wild and C‑33A‑SNAI2 groups was significantly decreased (P<0.01). The results of beta‑galactosidase staining showed that the proportion of beta‑galactosidase‑positive cells in the C‑33A‑SNAI2 group was significantly decreased compared with the C‑33A‑Wild group (P<0.01). Upregulation of SNAI2 enhanced the increase in p21 expression, and the decrease in CDK1, urokinase plasminogen activator receptor (u‑PAR) and cyclin D1 expression in C‑33A cells compared with C‑33A‑Wild cells (P<0.05). In addition, the activities of p38, ERK1/2 and the phosphorylated (p)‑ERK1/2/p‑p38 ratio were decreased in the C‑33A‑SNAI2 group compared with the C‑33A‑Wild and HeLa groups (P<0.05). In conclusion, SNAI2 enhanced HPV‑negative cervical cancer C‑33A cell dormancy, which was characterized by G0/G1 arrest, by the downregulation of u‑PAR expression, and a decrease in the activity of the p‑ERK1/2 and p‑p38MAPK signaling pathways in vitro. Cancer recurrence and metastases are responsible for most cancer‑related deaths. Given that SNAI2 is required for enhancing HPV‑negative cervical cancer cell dormancy, regulating this process may promote cervical tumor cells to enter a continuous dormant state, which could be a potential approach for tumor therapy.

Bone niches in the regulation of tumour cell dormancy

Secondary metastases, accounting for 90 % of cancer-related deaths, pose a formidable challenge in cancer treatment, with bone being a prevalent site. Importantly, tumours may relapse, often in the skeleton even after successful eradication of the primary tumour, indicating that tumour cells may lay dormant within bone for extended periods of time. This review summarises recent findings in the mechanisms underlying tumour cell dormancy and the role of bone cells in this process. Hematopoietic stem cell (HSC) niches in bone provide a model for understanding regulatory microenvironments. Dormant tumour cells have been shown to exploit similar niches, with evidence suggesting interactions with osteoblast-lineage cells and other stromal cells via CXCL12-CXCR4, integrins, and TAM receptor signalling, especially through GAS6-AXL, led to dormancy, with exit of dormancy potentially regulated by osteoclastic bone resorption and neuronal signalling. A comprehensive understanding of dormant tumour cell niches and their regulatory mechanisms is essential for developing targeted therapies, a critical step towards eradicating metastatic tumours and stopping disease relapse.

Tumor Dormancy and Reactivation: The Role of Heat Shock Proteins

Tumors are a heterogeneous group of cell masses originating in various organs or tissues. The cellular composition of the tumor cell mass interacts in an intricate manner, influenced by humoral, genetic, molecular, and tumor microenvironment cues that dictate tumor growth or suppression. As a result, tumors undergo a period of a dormant state before their clinically discernible stage, which surpasses the clinical dormancy threshold. Moreover, as a genetically imprinted strategy, early-seeder cells, a distinct population of tumor cells, break off to dock nearby or extravasate into blood vessels to secondary tissues, where they form disseminated solitary dormant tumor cells with reversible capacity. Among the various mechanisms underlying the dormant tumor mass and dormant tumor cell formation, heat shock proteins (HSPs) might play one of the most important roles in how the dormancy program plays out. It is known that numerous aberrant cellular processes, such as malignant transformation, cancer cell stemness, tumor invasion, metastasis, angiogenesis, and signaling pathway maintenance, are influenced by the HSPs. An accumulating body of knowledge suggests that HSPs may be involved in the angiogenic switch, immune editing, and extracellular matrix (ECM) remodeling cascades, crucial genetically imprinted strategies important to the tumor dormancy initiation and dormancy maintenance program. In this review, we highlight the biological events that orchestrate the dormancy state and the body of work that has been conducted on the dynamics of HSPs in a tumor mass, as well as tumor cell dormancy and reactivation. Additionally, we propose a conceptual framework that could possibly underlie dormant tumor reactivation in metastatic relapse.

Advances in circulating tumor cells for early detection, prognosis and metastasis reduction in lung cancer

Globally, lung cancer stands as the leading type of cancer in terms of incidence and is the major source of mortality attributed to cancer. We have outlined the molecular biomarkers for lung cancer that are available clinically. Circulating tumor cells (CTCs) spread from the original location, circulate in the bloodstream, extravasate, and metastasize, forming secondary tumors by invading and establishing a favorable environment. CTC analysis is considered a common liquid biopsy method for lung cancer. We have enumerated both in vivo and ex vivo techniques for CTC separation and enrichment, examined the advantages and limitations of these methods, and also discussed the detection of CTCs in other bodily fluids. We have evaluated the value of CTCs, as well as CTCs in conjunction with other biomarkers, for their utility in the early detection and prognostic assessment of patients with lung cancer. CTCs engage with diverse cells of the metastatic process, interfering with the interaction between CTCs and various cells in metastasis, potentially halting metastasis and enhancing patient prognosis.

Cancer stem-like cells in uveal melanoma: novel insights and therapeutic implications

Uveal melanoma (UM) is the most common primary ocular tumor in the adult population. Even though these primary tumors are successfully treated in 90% of cases, almost 50% of patients ultimately develop metastasis, mainly in the liver, via hematological dissemination, with a median survival spanning from 6 to 12 months after diagnosis. In this context, chemotherapy regimens and molecular targeted therapies have demonstrated poor response rates and failed to improve survival. Among the multiple reasons for therapy failure, the presence of cancer stem-like cells (CSCs) represents the main cause of resistance to anticancer therapies. In the last few years, the existence of CSCs in UM has been demonstrated both in preclinical and clinical studies, and new molecular pathways and mechanisms have been described for this subpopulation of UM cells. Here, we will discuss the state of the art of CSC biology and their potential exploitation as therapeutic target in UM.

Metastatic organotropism: a brief overview

Organotropism has been known since 1889, yet this vital component of metastasis has predominantly stayed elusive. This mini-review gives an overview of the current understanding of the underlying mechanisms of organotropism and metastases development by focusing on the formation of the pre-metastatic niche, immune defenses against metastases, and genomic alterations associated with organotropism. The particular case of brain metastases is also addressed, as well as the impact of organotropism in cancer therapy. The limited comprehension of the factors behind organotropism underscores the necessity for efficient strategies and treatments to manage metastases.

Oncolytic Adenovirus for the Targeting of Paclitaxel-Resistant Breast Cancer Stem Cells

Adjuvant systemic therapies effectively reduce the risk of breast cancer recurrence and metastasis, but therapy resistance can develop in some patients due to breast cancer stem cells (BCSCs). Oncolytic adenovirus (OAd) represents a promising therapeutic approach as it can specifically target cancer cells. However, its potential to target BCSCs remains unclear. Here, we evaluated a Cox-2 promoter-controlled, Ad5/3 fiber-modified OAd designed to encode the human sodium iodide symporter (hNIS) in breast cancer models. To confirm the potential of OAds to target BCSCs, we employed BCSC-enriched estrogen receptor-positive (ER+) paclitaxel-resistant (TaxR) cells and tumorsphere assays. OAd-hNIS demonstrated significantly enhanced binding and superior oncolysis in breast cancer cells, including ER+ cells, while exhibiting no activity in normal mammary epithelial cells. We observed improved NIS expression as the result of adenovirus death protein deletion. OAd-hNIS demonstrated efficacy in targeting TaxR BCSCs, exhibiting superior killing and hNIS expression compared to the parental cells. Our vector was capable of inhibiting tumorsphere formation upon early infection and reversing paclitaxel resistance in TaxR cells. Importantly, OAd-hNIS also destroyed already formed tumorspheres seven days after their initiation. Overall, our findings highlight the promise of OAd-hNIS as a potential tool for studying and targeting ER+ breast cancer recurrence and metastasis.

Phenotypic plasticity - Implications for tumours in bone

Metastasis is a major contributor to cancer patient mortality. Tumour cells often develop phenotypic plasticity to successfully metastasize to different target organs. Recent progress in the study of bone metastasis has provided novel insight into the biological processes that drive the spread and growth of cancer cells in the bone. In this review, we provide a summary of how the bone marrow microenvironment promotes phenotypic plasticity of metastatic tumour cells and alters therapeutic responses. We highlight pivotal transformations in cellular status driven by plasticity, including mesenchymal-epithelial transition, acquisition of stem-like traits, and awakening from dormancy. Additionally, we describe the phenomenon of host-organ mimicry and metabolic rewiring that collectively serve as key attributes of disseminated tumour cells, enabling their successful colonization and growth within the bone marrow microenvironment.

Tumor-to-Tumor Metastasis of Lung Cancer to Kidney Cancer: A Review of the Literature and Our Experience

Tumor-to-tumor metastasis (TTM) is a rare phenomenon documented in patients with multiple primary cancers. This condition is defined as a metastasis between two true primary tumors. The most frequently reported recipient tumor is renal cell carcinoma (RCC), and the lung carcinomas are the most common metastatic tumor donors. Therefore, this paper attempts to address the current gap in knowledge about this rare phenomenon. The first part of this review outlines the recently proposed models and mechanisms involved in the TTM process. The second part then summarizes and analyzes previous case reports in the literature. We also present our experience with the case of lung cancer that metastasized into RCC. Given the sporadic incidence of TTM, no specific management guidelines exist. Therefore, considering TTM in patients with multiple primary tumors is important as it could potentially modify the oncological management offered.

Targeting SMAD-Dependent Signaling: Considerations in Epithelial and Mesenchymal Solid Tumors

SMADs are the canonical intracellular effector proteins of the TGF-β (transforming growth factor-β). SMADs translocate from plasma membrane receptors to the nucleus regulated by many SMAD-interacting proteins through phosphorylation and other post-translational modifications that govern their nucleocytoplasmic shuttling and subsequent transcriptional activity. The signaling pathway of TGF-β/SMAD exhibits both tumor-suppressing and tumor-promoting phenotypes in epithelial-derived solid tumors. Collectively, the pleiotropic nature of TGF-β/SMAD signaling presents significant challenges for the development of effective cancer therapies. Here, we review preclinical studies that evaluate the efficacy of inhibitors targeting major SMAD-regulating and/or -interacting proteins, particularly enzymes that may play important roles in epithelial or mesenchymal compartments within solid tumors.

Donors risk assessment in transplantation: From the guidelines to their real-world application

Transplantation of an organ from a donor carries an unavoidable risk of tumor transmission. The need to extend the donor pool increases the use of organs from donors with malignancies and potential disease transmission is a constant tension influencing donor suitability decisions. Current classification systems for the assessment of donor malignancy transmission risk have evolved from reports of potential transmission events in recipients to national donation and transplant surveillance agencies. Although the risk of malignancy transmission is very low in the general transplant setting it must constantly be balanced with the transplant benefits. Guidelines are mainly based on large registries and sparse case reports of transmission, so they cannot cover all the possible situations. For this reason, in 2004 in Italy, the National Transplant Center gave rise to the Second Opinion Service, charged by the Ministry of Health, by structuring expertise in diagnostic oncology and risk transmission and making it available to the Italian Transplant Centers. In this paper the registry of the Italian Oncological Second Opinion was reviewed, from 2016 to 2018, to detail the most frequent and problematic neoplastic topics addressed, those are separately reported and discussed. Furthermore, a review of the most recent strategies and risk stratification is provided, according to the most recent literature evidence and to the European Guidelines.

Tumor-derived cell-free DNA and circulating tumor cells: partners or rivals in metastasis formation?

The origin of metastases is a topic that has sparked controversy. Despite recent advancements, metastatic disease continues to pose challenges. The first admitted model of how metastases develop revolves around cells breaking away from the primary tumor, known as circulating tumor cells (CTCs). These cells survive while circulating through the bloodstream and subsequently establish themselves in secondary organs, a process often referred to as the "metastatic cascade". This intricate and dynamic process involves various steps, but all the mechanisms behind metastatic dissemination are not yet comprehensively elucidated. The "seed and soil" theory has shed light on the phenomenon of metastatic organotropism and the existence of pre-metastatic niches. It is now established that these niches can be primed by factors secreted by the primary tumor before the arrival of CTCs. In particular, exosomes have been identified as important contributors to this priming. Another concept then emerged, i.e. the "genometastasis" theory, which challenged all other postulates. It emphasizes the intriguing but promising role of cell-free DNA (cfDNA) in metastasis formation through oncogenic formation of recipient cells. However, it cannot be ruled out that all these theories are intertwined. This review outlines the primary theories regarding the metastases formation that involve CTCs, and depicts cfDNA, a potential second player in the metastasis formation. We discuss the potential interrelationships between CTCs and cfDNA, and propose both in vitro and in vivo experimental strategies to explore all plausible theories.

Comparative efficacy and safety of extended adjuvant endocrine therapy for hormone receptor-positive early breast cancer: a Bayesian network meta-analysis

PURPOSE

Optimal extended adjuvant endocrine therapy (ET) duration and strategy for hormone receptor-positive (HR +) early breast cancer remain unclear. In this network meta-analysis (NMA), the efficacy and safety of all available extended adjuvant ETs were compared and ranked.

METHODS

PubMed, Embase, and Cochrane Library and abstracts presented at ASCO, SABCS, and ESMO were searched on March 5, 2022. Fourteen randomized controlled trials (RCTs) comprising eight extended adjuvant ETs for HR + breast cancer and 38,070 patients were analyzed. Main outcomes were disease-free survival (DFS), overall survival (OS), grade ≥ 3 adverse events (AEs), and contralateral breast cancer (CBC). Direct and indirect comparisons were integrated via Bayesian NMA. Hierarchical cluster analysis was performed to jointly rank efficacy and safety outcomes.

RESULTS

Compared with that of 5 year ET, extended 10 year aromatase inhibitor (AI) treatment provided the greatest DFS benefit (HR = 0.45, 95%CrI 0.23-0.83), whereas no strategy differed significantly in terms of the other main outcomes. Extended 10 year AI treatment was the preferred strategy for DFS improvement and CBC prevention (surface under the cumulative ranking curve: 93.51% and 91.29% probability, respectively). All strategies had comparable safeties (grade ≥ 3 AEs). Compared with that of 5 year ET, 10 year extended AI significantly increased arthralgia (OR = 1.65, 95%CrI 1.02-2.93) and osteoporosis (OR = 3.33, 95%CrI 1.19-9.68).

CONCLUSION

Extended 10 year AI therapy may be optimal for HR + early breast cancer given its relatively high efficacy and safety.

Targeting endoplasmic reticulum associated degradation pathway combined with radiotherapy enhances the immunogenicity of esophageal cancer cells

Immunogenic cell death (ICD) is essential for the activation of immune system against cancer. We aimed to investigate the efficacy of endoplasmic reticulum (ER)-associated protein degradation (ERAD) inhibitors (EerI and NMS-873) in enhancing radiation-induced ICD in esophageal cancer (EC). EC cells were administered with ERAD inhibitors, radiation therapy (RT), and the combination treatment. ICD hallmarks including calreticulin (CALR), adenosine triphosphate (ATP), and high mobility group protein B1 (HMGB1) were detected. The efficacy of ERAD inhibitors combined with RT in stimulating ICD was analyzed. Additionally, the role of ICD hallmarks in immune cell infiltration and patient survival was investigated. Inhibiting ERAD pathways was able to stimulate ICD component emission from dying EC cells in a dose-dependent pattern. Radiation-induced ICD was significantly increased after high doses RT (≥10 Gy). ERAD inhibitor combined with moderate dose RT (≥6 Gy) was capable of stimulating increased ICD in EC cells. Dual therapy could elicit the antitumor immune response by enhancing dendritic cells maturation and phagocytosis. Further investigation revealed a significant correlation between CALR and tumor-infiltrating immune cells. Low expression of ATP and HMGB1 and high expression of CALR were associated with favorable survival in patients with EC. The immunogenicityof EC can be enhanced by ERAD inhibitors combined with moderate doses of RT. ICD hallmark genes, especially CALR, are correlated to immune cell infiltration and clinical outcomes in EC. The present results demonstrated an important method to improve the immunogenicity of EC cells for enhanced antitumor immune response.

Premetastatic Niche Mimicking Bone-On-A-Chip: A Microfluidic Platform to Study Bone Metastasis in Cancer Patients

Primary cancer modulates the bone microenvironment to sow the seeds of dormancy and metastasis in tumor cells, leading to multiple organ metastasis and death. In this study, 3D printing and bone-on-a-chip (BOC) are combined to develop a BOC platform that mimics the pre-metastatic niches (PMNs) and facilitates elucidation of the interactions between bone-resident cells and metastatic tumor cells under the influence of primary cancer. Photocrosslinkable gelatin methacrylate (GelMA) is used as a 3D culturing hydrogel to encapsulate cells, and circulate tumor culture medium (CM) adjacent to the hydrogel to verify the critical role of mesenchymal stem cells (MSCs) and osteoclasts (RAW264.7s). Three niches: the dormancy niche, the perivascular niche, and the "vicious cycle" niche, are devised to recapitulate bone metastasis in one chip with high cell viability and excellent nutrient exchange. With respect to tumor dormancy and reactivation, the invadopodia formation of A549 lung cancer cells in communication with MSCs and RAW264.7 via the cortactin pathway is researched. As a proof of concept, the functionality and practicality of the platform are demonstrated by analyzing the invadopodia formation and the influence of various cells, and the establishment of the dynamic niches paves the way to understanding PMN formation and related drug discovery.

Targeting Translation and the Cell Cycle Inversely Affects CTC Metabolism but Not Metastasis

Melanoma brain metastasis (MBM) is significantly associated with poor prognosis and is diagnosed in 80% of patients at autopsy. Circulating tumor cells (CTCs) are "seeds" of metastasis and the smallest functional units of cancer. Our multilevel approach has previously identified a CTC RPL/RPS gene signature directly linked to MBM onset. We hypothesized that targeting ribogenesis prevents MBM/metastasis in CTC-derived xenografts. We treated parallel cohorts of MBM mice with FDA-approved protein translation inhibitor omacetaxine with or without CDK4/CDK6 inhibitor palbociclib, and monitored metastatic development and cell proliferation. Necropsies and IVIS imaging showed decreased MBM/extracranial metastasis in drug-treated mice, and RNA-Seq on mouse-blood-derived CTCs revealed downregulation of four RPL/RPS genes. However, mitochondrial stress tests and RT-qPCR showed that omacetaxine and palbociclib inversely affected glycolytic metabolism, demonstrating that dual targeting of cell translation/proliferation is critical to suppress plasticity in metastasis-competent CTCs. Equally relevant, we provide the first-ever functional metabolic characterization of patient-derived circulating neoplastic cells/CTCs.

Resistance to 2-Hydroxy-Flutamide in Prostate Cancer Cells Is Associated with the Downregulation of Phosphatidylcholine Biosynthesis and Epigenetic Modifications

In this study, we examined the metabolic adaptations of a chemoresistant prostate cancer cell line in comparison to a sensitive cell line. We utilized prostate cancer LNCaP cells and subjected them to a stepwise increase in the antiandrogen 2-hydroxy-flutamide (FLU) concentration to generate a FLU-resistant cell line (LN-FLU). These LN-FLU cells displayed characteristics of cancer stem cells, exhibited drug resistance, and showed a significantly reduced expression of Cyclin D1, along with the overexpression of p16, pointing to a proliferation arrest. In comparing the cancer stem-like LN-FLU cells to the LNCaP cells, we observed a decrease in the expression of CTP-choline cytidylyl transferase α (CCTα), as well as a decline in choline kinase, suggesting altogether a downregulation of the phosphatidylcholine biosynthetic pathway. In addition, we found decreased levels of the protein methyl transferase PRMT2 and the upregulation of the histone deacetylase Sirtuin1 (Sirt1). Analysis of the human prostate cancer samples revealed similar results in a population with high expressions of the stem cell markers Oct4 and ABCB1A1. Our findings suggest that the adaptation of prostate cancer cells to antiandrogens could induce reprogramming into stem cells that survive in a low phosphocholine metabolism and cell cycle arrest and display drug resistance.

Immunomodulatory and pro-oncologic effects of ketamine and isoflurane anesthetics in a murine model

INTRODUCTION

Volatile and intravenous anesthetics may worsen oncologic outcomes in basic science animal models. These effects may be related to suppressed innate and adaptive immunity, decreased immunosurveillance, and disrupted cellular signaling. We hypothesized that anesthetics would promote lung tumor growth via altered immune function in a murine model and tested this using an immunological control group of immunodeficient mice.

METHODS

Lewis lung carcinoma cells were injected via tail vein into C57BL/6 immunocompetent and NSG immunodeficient mice during exposure to isoflurane and ketamine versus controls without anesthesia. Mice were imaged on days 0, 3, 10, and 14 post-tumor cell injection. On day 14, mice were euthanized and organs fixed for metastasis quantification and immunohistochemistry staining. We compared growth of tumors measured from bioluminescent imaging and tumor metastasis in ex vivo bioluminescent imaging of lung and liver.

RESULTS

Metastases were significantly greater for immunocompromised NSG mice than immunocompetent C57BL/6 mice over the 14-day experiment (partial η2 = 0.67, 95% CI = 0.54, 0.76). Among immunocompetent mice, metastases were greatest for mice receiving ketamine, intermediate for those receiving isoflurane, and least for control mice (partial η2 = 0.88, 95% CI = 0.82, 0.91). In immunocompetent mice, significantly decreased T lymphocyte (partial η2 = 0.83, 95% CI = 0.29, 0.93) and monocyte (partial η2 = 0.90, 95% CI = 0.52, 0.96) infiltration was observed in anesthetic-treated mice versus controls.

CONCLUSIONS

The immune system appears central to the pro-metastatic effects of isoflurane and ketamine in a murine model, with decreased T lymphocytes and monocytes likely playing a role.

MiR-662 is associated with metastatic relapse in early-stage breast cancer and promotes metastasis by stimulating cancer cell stemness

BACKGROUND

Breast cancer (BC) metastasis, which often occurs in bone, contributes substantially to mortality. MicroRNAs play a fundamental role in BC metastasis, although microRNA-regulated mechanisms driving metastasis progression remain poorly understood.

METHODS

MiRome analysis in serum from BC patients was performed by TaqMan™ low-density array. MiR-662 was overexpressed following MIMIC-transfection or lentivirus transduction. Animal models were used to investigate the role of miR-662 in BC (bone) metastasis. The effect of miR-662-overexpressing BC cell conditioned medium on osteoclastogenesis was investigated. ALDEFLUOR assays were performed to study BC stemness. RNA-sequencing transcriptomic analysis of miR-662-overexpressing BC cells was performed to evaluate gene expression changes.

RESULTS

High levels of hsa-miR-662 (miR-662) in serum from BC patients, at baseline (time of surgery), were associated with future recurrence in bone. At an early-stage of the metastatic disease, miR-662 could mask the presence of BC metastases in bone by inhibiting the differentiation of bone-resorbing osteoclasts. Nonetheless, metastatic miR-662-overexpressing BC cells then progressed as overt osteolytic metastases thanks to increased stem cell-like traits.

CONCLUSIONS

MiR-662 is involved in BC metastasis progression, suggesting it may be used as a prognostic marker to identify BC patients at high risk of metastasis.

The role of mesenchymal stem cells derived exosomes as a novel nanobiotechnology target in the diagnosis and treatment of cancer

Mesenchymal stem cells (MSCs), one of the most common types of stem cells, are involved in the modulation of the tumor microenvironment (TME). With the advancement of nanotechnology, exosomes, especially exosomes secreted by MSCs, have been found to play an important role in the initiation and development of tumors. In recent years, nanobiotechnology and bioengineering technology have been gradually developed to detect and identify exosomes for diagnosis and modify exosomes for tumor treatment. Several novel therapeutic strategies bioengineer exosomes to carry drugs, proteins, and RNAs, and further deliver their encapsulated cargoes to cancer cells through the properties of exosomes. The unique properties of exosomes in cancer treatment include targeting, low immunogenicity, flexibility in modification, and high biological barrier permeability. Nevertheless, the current comprehensive understanding of the roles of MSCs and their secreted exosomes in cancer development remain inadequate. It is necessary to better understand/update the mechanism of action of MSCs-secreted exosomes in cancer development, providing insights for better modification of exosomes through bioengineering technology and nanobiotechnology. Therefore, this review focuses on the role of MSCs-secreted exosomes and bioengineered exosomes in the development, progression, diagnosis, and treatment of cancer.

Glioblastoma Biology, Genetics and Possible Therapies

Glioblastoma is the most aggressive intracranial tumor [...].

MAGI1 Prevents Senescence and Promotes the DNA Damage Response in ER+ Breast Cancer

MAGI1 acts as a tumor suppressor in estrogen receptor-positive (ER+) breast cancer (BC), and its loss correlates with a more aggressive phenotype. To identify the pathways and events affected by MAGI1 loss, we deleted the MAGI1 gene in the ER+ MCF7 BC cell line and performed RNA sequencing and functional experiments in vitro. Transcriptome analyses revealed gene sets and biological processes related to estrogen signaling, the cell cycle, and DNA damage responses affected by MAGI1 loss. Upon exposure to TNF-α/IFN-γ, MCF7 MAGI1 KO cells entered a deeper level of quiescence/senescence compared with MCF7 control cells and activated the AKT and MAPK signaling pathways. MCF7 MAGI1 KO cells exposed to ionizing radiations or cisplatin had reduced expression of DNA repair proteins and showed increased sensitivity towards PARP1 inhibition using olaparib. Treatment with PI3K and AKT inhibitors (alpelisib and MK-2206) restored the expression of DNA repair proteins and sensitized cells to fulvestrant. An analysis of human BC patients' transcriptomic data revealed that patients with low MAGI1 levels had a higher tumor mutational burden and homologous recombination deficiency. Moreover, MAGI1 expression levels negatively correlated with PI3K/AKT and MAPK signaling, which confirmed our in vitro observations. Pharmacological and genomic evidence indicate HDACs as regulators of MAGI1 expression. Our findings provide a new view on MAGI1 function in cancer and identify potential treatment options to improve the management of ER+ BC patients with low MAGI1 levels.

Persistent Circulating Tumor Cells at 1 Year After Oncologic Resection Predict Late Recurrence in Pancreatic Cancer

OBJECTIVE

The aim of the study was to assess the association between persistent circulating tumor cells (CTCs) and subsequent recurrence in patients who were clinically recurrence free ~12 months postoperatively.

BACKGROUND

Circulating tumor cells have been proposed as biomarkers to predict survival in pancreatic cancer. Some patients demonstrate persistent CTCs postoperatively, which could represent minimal residual disease.

METHODS

Patients from previously published prospective circulating tumor cell in pancreatic cancer trial without clinical evidence of recurrence 12 months postoperatively and CTC testing performed 9 to 15 months postoperatively were included. The presence of epithelial and transitional CTCs (trCTCs) was evaluated as predictor of recurrence. Kaplan-Meier curve, log-rank test, and Cox model were used for survival analysis.

RESULTS

Thirty-three of 129 eligible patients (circulating tumor cell in pancreatic cancer trial) were included. The trCTC-positive and negative patients were well balanced in clinicopathologic features. Patients with trCTCs had a recurrence rate per-person-month of 10.3% compared with 3.1% in trCTCs-negative patients with a median time to recurrence of 3.9 versus 27.1 months, respectively. On multivariable analysis, trCTCs positivity was associated with higher risk of late recurrence (hazard ratio: 4.7, 95% CI, 1.2-18.3, P =0.024). Fourteen (42.4%) patients recurred during the second postoperative year. One-year postoperative trCTCs positivity was associated with a higher rate of recurrence during the second year (odds ratio:13.1, 95% CI, 1.6-1953.4, P =0.028, area under curve=0.72). Integrating clinicopathologic features with trCTCs increased the area under curve to 0.80. A majority of trCTCs-positive patients (N=5, 62.5%) had multisite recurrence, followed by local-only (N=2, 25.0%) and liver-only (N=1, 12.5%) recurrence. This was in striking contrast to trCTCs-negative patients, where a majority (N=6, 66.7%) had a local-only recurrence, followed by liver-only (N=2, 22.2%) and multisite (N=1, 11.1%) recurrence.

CONCLUSIONS

In patients deemed to be clinically disease-free 12 months postoperatively, trCTCs positivity is associated with higher rates of subsequent recurrence with distinct patterns of recurrence. CTCs could be used a putative biomarker to guide patient prognostication and management in pancreatic cancer.

Live Cell Lineage Tracing of Dormant Cancer Cells

Breast cancer is a leading cause of global cancer-related deaths, and metastasis is the overwhelming culprit of poor patient prognosis. The most nefarious aspect of metastasis is dormancy, a prolonged period between primary tumor resection and relapse. Current therapies are insufficient at killing dormant cells; thus, they can remain quiescent in the body for decades until eventually undergoing a phenotypic switch, resulting in metastases that are more adaptable and drug resistant. Unfortunately, dormancy has few in vitro models, largely because lab-derived cell lines are highly proliferative. Existing models address tumor dormancy, not cellular dormancy, because tracking individual cells is technically challenging. To combat this problem, a live cell lineage approach to find and track individual dormant cells, distinguishing them from proliferative and dying cells over multiple days, is adapted. This approach is applied across a range of different in vitro microenvironments. This approach reveals that the proportion of cells that exhibit long-term quiescence is regulated by both cell intrinsic and extrinsic factors, with the most dormant cells found in 3D collagen gels. This paper envisions that this approach will prove useful to biologists and bioengineers in the dormancy community to identify, quantify, and study dormant tumor cells.

Rationale and trial design of NATALEE: a Phase III trial of adjuvant ribociclib + endocrine therapy versus endocrine therapy alone in patients with HR+/HER2- early breast cancer

Background

Ribociclib has demonstrated a statistically significant overall survival benefit in pre- and postmenopausal patients with hormone receptor positive/human epidermal growth factor receptor 2 negative (HR+/HER2-) advanced breast cancer. New Adjuvant Trial with Ribociclib [LEE011] (NATALEE) is a trial evaluating the efficacy and safety of adjuvant ribociclib plus endocrine therapy (ET) versus ET alone in patients with HR+/HER2- early nonmetastatic breast cancer (EBC).

Methods/design

NATALEE is a multicenter, randomized, open-label, Phase III trial in patients with HR+/HER2- EBC. Eligible patients include women, regardless of menopausal status, and men aged ⩾18 years. Select patients with stage IIA, stage IIB, or stage III disease (per the anatomic classification in the AJCC Cancer Staging Manual, 8th edition) with an initial diagnosis ⩽18 months prior to randomization are eligible. Patients receiving standard (neo)adjuvant ET are eligible if treatment was initiated ⩽12 months before randomization. Patients undergo 1:1 randomization to ribociclib 400 mg/day (3 weeks on/1 week off) +ET (letrozole 2.5 mg/day or anastrozole 1 mg/day [investigator's discretion] plus goserelin [men or premenopausal women]) or ET alone. Ribociclib treatment duration is 36 months; ET treatment duration is ⩾60 months. The primary end point is invasive disease-free survival.

Discussion

The 36-month treatment duration of ribociclib in NATALEE is extended compared with that in other adjuvant cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitor trials and is intended to maximize efficacy due to longer duration of CDK4/6 inhibition. Compared with the 600-mg/day dose used in advanced breast cancer, the reduced ribociclib dose used in NATALEE may improve tolerability while maintaining efficacy. NATALEE includes the broadest population of patients with HR+/HER2- EBC of any Phase III trial currently evaluating adjuvant CDK4/6 inhibitor treatment.

Trial registration

ClinicalTrials.gov identifier: NCT03701334 (https://clinicaltrials.gov/ct2/show/NCT03701334).

KISS1 metastasis suppressor in tumor dormancy: a potential therapeutic target for metastatic cancers?

Present therapeutic approaches do not effectively target metastatic cancers, often limited by their inability to eliminate already-seeded non-proliferative, growth-arrested, or therapy-resistant tumor cells. Devising effective approaches targeting dormant tumor cells has been a focus of cancer clinicians for decades. However, progress has been limited due to limited understanding of the tumor dormancy process. Studies on tumor dormancy have picked up pace and have resulted in the identification of several regulators. This review focuses on KISS1, a metastasis suppressor gene that suppresses metastasis by keeping tumor cells in a state of dormancy at ectopic sites. The review explores mechanistic insights of KISS1 and discusses its potential application as a therapeutic against metastatic cancers by eliminating quiescent cells or inducing long-term dormancy in tumor cells.

Metastasis prevention: How to catch metastatic seeds

Despite considerable advances in the evolution of anticancer therapies, metastasis still remains the main cause of cancer mortality. Therefore, current strategies for cancer cure should be redirected towards prevention of metastasis. Targeting metastatic pathways represents a promising therapeutic opportunity aimed at obstructing tumor cell dissemination and metastatic colonization. In this review, we focus on preclinical studies and clinical trials over the last five years that showed high efficacy in suppressing metastasis through targeting lymph node dissemination, tumor cell extravasation, reactive oxygen species, pre-metastatic niche, exosome machinery, and dormancy.

Exosomes from LSD1 knockdown breast cancer cells activate osteoclastogenesis and inhibit osteoblastogenesis

Bone metastasis is a common and incurable complication of breast cancer. Lysine-specific demethylase 1 (LSD1), a histone demethylase, plays an important role in the metastasis of breast cancer. However, the role of LSD1 in bone metastasis of breast cancer is unclear. We hypothesized that exosomes from LSD1 knockdown breast cancer cells promote bone metastasis by remodeling bone microenvironment. To verify this hypothesis, exosomes from LSD1 knockdown Estrogen receptor-positive cancer cell lines, MCF7 and T47D, were isolated, and the effects of these exosomes on osteoblast and osteoclast differentiation were investigated. Interestingly, exosomes from LSD1 knockdown breast cancer cells inhibited osteoblast differentiation and promoted osteoclast differentiation. Mechanistically, miR-6881-3p was decreased in the exosomes from LSD1 knockdown cells, and miR-6881-3p suppressed the expression of pre-B-cell leukemia homeobox 1 (PBX1) and additional sex combs like-2 (ASXL2), two genes with essential functions in osteoblast and osteoclast differentiations respectively. Transfection of miR-6881-3p into LSD1 knockdown cells reversed the effects of the exosomes on osteoblast and osteoclast differentiations. Our study reveals important roles of LSD1 on the regulation of exosomal miRNAs and the formation of favorable bone microenvironment for metastasis.

Natural Killer Cell-Derived Extracellular Vesicles as a Promising Immunotherapeutic Strategy for Cancer: A Systematic Review

Cancer is the second leading contributor to global deaths caused by non-communicable diseases. The cancer cells are known to interact with the surrounding non-cancerous cells, including the immune cells and stromal cells, within the tumor microenvironment (TME) to modulate the tumor progression, metastasis and resistance. Currently, chemotherapy and radiotherapy are the standard treatments for cancers. However, these treatments cause a significant number of side effects, as they damage both the cancer cells and the actively dividing normal cells indiscriminately. Hence, a new generation of immunotherapy using natural killer (NK) cells, cytotoxic CD8⁺ T-lymphocytes or macrophages was developed to achieve tumor-specific targeting and circumvent the adverse effects. However, the progression of cell-based immunotherapy is hindered by the combined action of TME and TD-EVs, which render the cancer cells less immunogenic. Recently, there has been an increase in interest in using immune cell derivatives to treat cancers. One of the highly potential immune cell derivatives is the NK cell-derived EVs (NK-EVs). As an acellular product, NK-EVs are resistant to the influence of TME and TD-EVs, and can be designed for "off-the-shelf" use. In this systematic review, we examine the safety and efficacy of NK-EVs to treat various cancers in vitro and in vivo.

C4orf47 contributes to the dormancy of pancreatic cancer under hypoxic conditions

In our comprehensive analysis of pancreatic cancer pathology, we found that the C4orf47 molecule was upregulated in hypoxic environments. C4orf47 is reported to be a centrosome-associated protein, but its biological significance in cancer is completely unknown; therefore, we assessed its role in pancreatic cancer. We found that C4orf47 was a direct target of HIF-1α and is upregulated in hypoxic conditions, in which it suppressed the cell cycle and inhibits cell proliferation through up-regulation of the cell cycle repressors Fbxw-7, P27, and p57; and the down-regulation of the cell cycle promoters c-myc, cyclinD1, and cyclinC. Furthermore, C4orf47 induced epithelial-mesenchymal transition and enhanced their cell plasticity and invasiveness. In addition, the p-Erk/p-p38 ratio was significantly enhanced and down-regulated CD44 expression by C4orf47 suppression, suggesting that C4orf47 is involved in pancreatic cancer dormancy under hypoxic conditions. Furthermore, the potential of C4orf47 expression was a good prognostic biomarker for pancreatic cancer. These results contribute to the elucidation of the pathology of refractory pancreatic cancer and the development of novel therapeutic strategies.

From ecology to oncology: To understand cancer stem cell dormancy, ask a Brine shrimp (Artemia)

The brine shrimp (Artemia), releases embryos that can remain dormant for up to a decade. Molecular and cellular level controlling factors of dormancy in Artemia are now being recognized or applied as active controllers of dormancy (quiescence) in cancers. Most notably, the epigenetic regulation by SET domain-containing protein 4 (SETD4), is revealed as highly conserved and the primary control factor governing the maintenance of cellular dormancy from Artemia embryonic cells to cancer stem cells (CSCs). Conversely, DEK, has recently emerged as the primary factor in the control of dormancy exit/reactivation, in both cases. The latter has been now successfully applied to the reactivation of quiescent CSCs, negating their resistance to therapy and leading to their subsequent destruction in mouse models of breast cancer, without recurrence or metastasis potential. In this review, we introduce the many mechanisms of dormancy from Artemia ecology that have been translated into cancer biology, and herald Artemia's arrival on the model organism stage. We show how Artemia studies have unlocked the mechanisms of the maintenance and termination of cellular dormancy. We then discuss how the antagonistic balance of SETD4 and DEK fundamentally controls chromatin structure and consequently governs CSCs function, chemo/radiotherapy resistance, and dormancy in cancers. Many key stages from transcription factors to small RNAs, tRNA trafficking, molecular chaperones, ion channels, and links with various pathways and aspects of signaling are also noted, all of which link studies in Artemia to those of cancer on a molecular and/or cellular level. We particularly emphasize that the application of such emerging factors as SETD4 and DEK may open new and clear avenues for the treatment for various human cancers.

In vivo metabolic imaging identifies lipid vulnerability in a preclinical model of Her2+/Neu breast cancer residual disease and recurrence

Recurrent cancer cells that evade therapy is a leading cause of death in breast cancer patients. This risk is high for women showing an overexpression of human epidermal growth factor receptor 2 (Her2). Cells that persist can rely on different substrates for energy production relative to their primary tumor counterpart. Here, we characterize metabolic reprogramming related to tumor dormancy and recurrence in a doxycycline-induced Her2+/Neu model of breast cancer with varying times to recurrence using longitudinal fluorescence microscopy. Glucose uptake (2-NBDG) and mitochondrial membrane potential (TMRE) imaging metabolically phenotype mammary tumors as they transition to regression, dormancy, and recurrence. “Fast-recurrence” tumors (time to recurrence ~55 days), transition from glycolysis to mitochondrial metabolism during regression and this persists upon recurrence. “Slow-recurrence” tumors (time to recurrence ~100 days) rely on both glycolysis and mitochondrial metabolism during recurrence. The increase in mitochondrial activity in fast-recurrence tumors is attributed to a switch from glucose to fatty acids as the primary energy source for mitochondrial metabolism. Consequently, when fast-recurrence tumors receive treatment with a fatty acid inhibitor, Etomoxir, tumors report an increase in glucose uptake and lipid synthesis during regression. Treatment with Etomoxir ultimately prolongs survival. We show that metabolic reprogramming reports on tumor recurrence characteristics, particularly at time points that are essential for actionable targets. The temporal characteristics of metabolic reprogramming will be critical in determining the use of an appropriate timing for potential therapies; namely, the notion that metabolic-targeted inhibition during regression reports long-term therapeutic benefit.

Osteoblastic protein kinase D1 contributes to the prostate cancer cells dormancy via GAS6-circadian clock signaling

Disseminated prostate cancer (PCa) is known to have a strong propensity for bone marrow. These disseminated tumor cells (DTCs) can survive in bone marrow for years without obvious proliferation, while maintaining the ability to develop into metastatic lesions. However, how DTCs kept dormant and recur is still uncertain. Here, we focus on the role of osteoblastic protein kinase D1 (PKD1) in PCa (PC-3 and DU145) dormancy using co-culture experiments. Using flow cytometry, western blotting, and immunofluorescence, we observed that in co-cultures osteoblasts could induce a dormant state in PCa cells, which is manifested by a fewer cell divisions, a decrease Ki-67-positive populations and a lower ERK/p38 ratio. In contrast, silencing of PKD1 gene in osteoblasts impedes co-cultured prostate cancer cell's dormancy ability. Mechanismly, protein kinase D1 (PKD1) in osteoblasts induces PCa dormancy via activating CREB1, which promoting the expression and secretion of growth arrest specific 6 (GAS6). Furthermore, GAS6-induced dormancy signaling significantly increased the expression of core circadian clock molecules in PCa cells, and a negative correlation of circadian clock proteins (BMAL1, CLOCK and DEC2) with recurrence-free survival is observed in metastatic prostate cancer patients. Interestingly, the expression of cell cycle factors (p21, p27, CDK1 and PCNA) which regulated by circadian clock also upregulated in response to GAS6 stimulation. Taken together, we provide evidence that osteoblastic PKD1/CREB1/GAS6 signaling regulates cellular dormancy of PCa cells, and highlights the importance of circadian clock in PCa cells dormancy.

Lipopolysaccharide sensitizes the therapeutic response of breast cancer to IAP antagonist

Inhibitor of apoptosis protein (IAP) is a class of E3 ubiquitin ligases functioning to support cancer survival and growth. Many small-molecule IAP antagonists have been developed, aiming to degrade IAP proteins to kill cancer. We have evaluated the effect of lipopolysaccharide (LPS), a component of the bacterial outer membrane, on IAP antagonists in treating breast cancer in a mouse model to guide future clinical trials. We show that LPS promotes IAP antagonist-induced regression of triple-negative breast cancer (TNBC) from MDA-MB-231 cells in immunodeficient mice. IAP antagonists such as SM-164, AT-406, and BV6, do not kill MDA-MB-231 cells alone, but allow LPS to induce cancer cell apoptosis rapidly. The apoptosis caused by LPS plus SM-164 is blocked by toll-like receptor 4 (TLR4) or MyD88 inhibitor, which inhibits LPS-induced TNFα production by the cancer cells. Consistent with this, MDA-MB-231 cell apoptosis induced by LPS plus SM-164 is also blocked by the TNF inhibitor. LPS alone does not kill MDA-MB-231 cells because it markedly increases the protein level of cIAP1/2, which is directly associated with and stabilized by MyD88, an adaptor protein of TLR4. ER⁺ MCF7 breast cancer cells expressing low levels of cIAP1/2 undergo apoptosis in response to SM-164 combined with TNFα but not with LPS. Furthermore, TNFα but not LPS alone inhibits MCF7 cell growth in vitro. Consistent with these, LPS combined with SM-164, but not either of them alone, causes regression of ER⁺ breast cancer from MCF7 cells in immunodeficient mice. In summary, LPS sensitizes the therapeutic response of both triple-negative and ER⁺ breast cancer to IAP antagonist therapy by inducing rapid apoptosis of the cancer cells through TLR4- and MyD88-mediated production of TNFα. We conclude that antibiotics that can reduce microbiota-derived LPS should not be used together with an IAP antagonist for cancer therapy.

Review old bone, new tricks

Despite the significant progress made over the past decade with combination of molecular profiling data and the development of new clinical strategies, our understanding of metastasis remains elusive. Bone metastasis is a complex process and a major cause of mortality in breast and prostate cancer patients, for which there is no effective treatment to-date. The current review summarizes the routes taken by the metastatic cells and the interactions between them and the bone microenvironment. We emphasize the role of the specified niches and cues that promote cellular adhesion, colonization, prolonged dormancy, and reactivation. Understanding these mechanisms will provide better insights for future studies and treatment strategies for bone metastatic conditions.

Circulatory Level of Inflammatory Cytoskeleton Signaling Regime Proteins in Cancer Invasion and Metastasis

Early detection of metastatic breast cancer (MBC) is a serious issue for the healthcare system. It is essential to develop potential non-invasive, low-cost molecular biomarkers. The present study explored specific serum proteins of inflammatory, MAPK, and cytoskeletal signaling pathways involved in the progression of MBC to establish a panel of blood-based diagnostic and prognostic biomarkers. Healthy-control (HC), non-metastatic (NM), and metastatic (M) (pre- and post-therapy) breast cancer (BC) patients were recruited. LOX5, Rac1, Rac1b, p38α, phospho-p38α (Y182), LIMK1, phospho-LIMK1 (T508), cofilin1, and phospho-cofilin1 (S3) were quantified in the serum of the study group by real-time label-free surface plasmon resonance technology and verified by Western blot. Proteins were found to be significantly elevated in the serum of BC patients compared to HC and also higher in M compared to NM, which further downregulated in post-therapy M patients. Elevation of phospho-LIMK1 and phospho-cofilin1, which are critical for M, was also indicated in the serum level and can differentiate from NM. Receiver operating characteristics (ROC) derived area under the curve (AUC) (0.9) is very strong to differentiate between HC and BC. Moreover, the combined ROC of 3 molecules phospho-LIMK, p38α, and phospho-p38α were found to be a potent predictive panel of biomarkers between M and NM with AUC0.95. The panel of inflammatory cytoskeleton signaling regime proteins specified in this study can have significant clinical utility for diagnosis as well as prognosis of MBC at an early stage. The study may have a high translational value in a simple and cost-effective way by avoiding frequent CT/PET scans.

Stromal changes in the aged lung induce an emergence from melanoma dormancy

Disseminated cancer cells from primary tumours can seed in distal tissues, but may take several years to form overt metastases, a phenomenon that is termed tumour dormancy. Despite its importance in metastasis and residual disease, few studies have been able to successfully characterize dormancy within melanoma. Here we show that the aged lung microenvironment facilitates a permissive niche for efficient outgrowth of dormant disseminated cancer cells-in contrast to the aged skin, in which age-related changes suppress melanoma growth but drive dissemination. These microenvironmental complexities can be explained by the phenotype switching model, which argues that melanoma cells switch between a proliferative cell state and a slower-cycling, invasive state1-3. It was previously shown that dermal fibroblasts promote phenotype switching in melanoma during ageing4-8. We now identify WNT5A as an activator of dormancy in melanoma disseminated cancer cells within the lung, which initially enables the efficient dissemination and seeding of melanoma cells in metastatic niches. Age-induced reprogramming of lung fibroblasts increases their secretion of the soluble WNT antagonist sFRP1, which inhibits WNT5A in melanoma cells and thereby enables efficient metastatic outgrowth. We also identify the tyrosine kinase receptors AXL and MER as promoting a dormancy-to-reactivation axis within melanoma cells. Overall, we find that age-induced changes in distal metastatic microenvironments promote the efficient reactivation of dormant melanoma cells in the lung.

Dormancy in Breast Cancer, the Role of Autophagy, lncRNAs, miRNAs and Exosomes

Breast cancer (BC) is the most frequently diagnosed cancer in women for which numerous diagnostic and therapeutic options have been developed. Namely, the targeted treatment of BC, for the most part, relies on the expression of growth factors and hormone receptors by these cancer cells. Despite this, close to 30% of BC patients may experience relapse due to the presence of minimal residual disease (MRD) consisting of surviving disseminated tumour cells (DTCs) from the primary tumour which can colonise a secondary site. This can lead to either detectable metastasis or DTCs entering a dormant state for a prolonged period where they are undetectable. In the latter, cells can re-emerge from their dormant state due to intrinsic and microenvironmental cues leading to relapse and metastatic outgrowth. Pre- and clinical studies propose that targeting dormant DTCs may inhibit metastasis, but the choice between keeping them dormant or forcing their “awakening” is still controversial. This review will focus on cancer cells’ microenvironmental cues and metabolic and molecular properties, which lead to dormancy, relapse, and metastatic latency in BC. Furthermore, we will focus on the role of autophagy, long non-coding RNAs (lncRNAs), miRNAs, and exosomes in influencing the induction of dormancy and awakening of dormant BC cells. In addition, we have analysed BC treatment from a viewpoint of autophagy, lncRNAs, miRNAs, and exosomes. We propose the targeted modulation of these processes and molecules as modern aspects of precision medicine for BC treatment, improving both novel and traditional BC treatment options. Understanding these pathways and processes may ultimately improve BC patient prognosis, patient survival, and treatment response.

Tuning Hydrogel Adhesivity and Degradability to Model the Influence of Premetastatic Niche Matrix Properties on Breast Cancer Dormancy and Reactivation

Dormant, disseminated tumor cells (DTCs) can persist for decades in secondary tissues before being reactivated to form tumors. The properties of the premetastatic niche can influence the DTC phenotype. To better understand how matrix properties of premetastatic niches influence DTC behavior, three hydrogel formulations are implemented to model a permissive niche and two nonpermissive niches. Poly(ethylene glycol) (PEG)-based hydrogels with varying adhesivity ([RGDS]) and degradability ([N-vinyl pyrrolidinone]) are implemented to mimic a permissive niche with high adhesivity and degradability and two nonpermissive niches, one with moderate adhesivity and degradability and one with no adhesivity and high degradability. The influence of matrix properties on estrogen receptor positive (ER⁺ ) breast cancer cells (MCF7s) is determined via a multimetric analysis. MCF7s cultured in the permissive niche adopted a growth state, while those in the nonpermissive niche with reduced adhesivity and degradability underwent tumor mass dormancy. Complete removal of adhesivity while maintaining high degradability induced single cell dormancy. The ability to mimic reactivation of dormant cells through a dynamic increase in [RGDS] is also demonstrated. This platform provides the capability of inducing growth, dormancy, and reactivation of ER⁺  breast cancer and can be useful in understanding how premetastatic niche properties influence cancer cell fate.

Resveratrol Contrasts IL-6 Pro-Growth Effects and Promotes Autophagy-Mediated Cancer Cell Dormancy in 3D Ovarian Cancer: Role of miR-1305 and of Its Target ARH-I

Tumor dormancy is the extended period during which patients are asymptomatic before recurrence, and it represents a difficult phenomenon to target pharmacologically. The relapse of tumors, for instance arising from the interruption of dormant metastases, is frequently observed in ovarian cancer patients and determines poor survival. Inflammatory cytokines present in the tumor microenvironment likely contribute to such events. Cancer cell dormancy and autophagy are interconnected at the molecular level through ARH-I (DIRAS3) and BECLIN-1, two tumor suppressors often dysregulated in ovarian cancers. IL-6 disrupts autophagy in ovarian cancer cells via miRNAs downregulation of ARH-I, an effect contrasted by the nutraceutical protein restriction mimetic resveratrol (RV). By using three ovarian cancer cell lines with different genetic background in 2D and 3D models, the latter mimicking the growth of peritoneal metastases, we show that RV keeps the cancer cells in a dormant-like quiescent state contrasting the IL-6 growth-promoting activity. Mechanistically, this effect is mediated by BECLIN-1-dependent autophagy and relies on the availability of ARH-I. We also show that ARH-I (DIRAS3) is a bona fide target of miR-1305, a novel oncomiRNA upregulated by IL-6 and downregulated by RV. Clinically relevant, bioinformatic analysis of a transcriptomic database showed that the high expression of DIRAS3 and MAP1LC3B mRNAs together with that of CDKN1A, directing a cellular dormant phenotype, predicts better overall survival in ovarian cancer patients, and this correlates with MIR1305 downregulation. The possibility of maintaining a permanent cell dormancy in ovarian cancer by the chronic administration of RV should be considered as a therapeutic option to prevent the "awakening" of cancer cells in response to a permissive microenvironment, thus limiting the risk of tumor relapse and metastasis.

Mini-Review: Can the Metastatic Cascade Be Inhibited by Targeting CD147/EMMPRIN to Prevent Tumor Recurrence?

Solid tumors metastasize very early in their development, and once the metastatic cell is lodged in a remote organ, it can proliferate to generate a metastatic lesion or remain dormant for long periods. Dormant cells represent a real risk for future tumor recurrence, but because they are typically undetectable and insensitive to current modalities of treatment, it is difficult to treat them in time. We describe the metastatic cascade, which is the process that allows tumor cells to detach from the primary tumor, migrate in the tissue, intravasate and extravasate the lymphatics or a blood vessel, adhere to a remote tissue and eventually outgrow. We focus on the critical enabling role of the interactions between tumor cells and immune cells, especially macrophages, in driving the metastatic cascade, and on those stages that can potentially be targeted. In order to prevent the metastatic cascade and tumor recurrence, we would need to target a molecule that is involved in all of the steps of the process, and evidence is brought to suggest that CD147/EMMPRIN is such a protein and that targeting it blocks metastasis and prevents tumor recurrence.

Bacterial Involvement in Progression and Metastasis of Colorectal Neoplasia

While the gut microbiome is composed of numerous bacteria, specific bacteria within the gut may play a significant role in carcinogenesis, progression, and metastasis of colorectal carcinoma (CRC). Certain microbial species are known to be associated with specific cancers; however, the interrelationship between bacteria and metastasis is still enigmatic. Mounting evidence suggests that bacteria participate in cancer organotropism during solid tumor metastasis. A critical review of the literature was conducted to better characterize what is known about bacteria populating a distant site and whether a tumor depends upon the same microenvironment during or after metastasis. The processes of carcinogenesis, tumor growth and metastatic spread in the setting of bacterial infection were examined in detail. The literature was scrutinized to discover the role of the lymphatic and venous systems in tumor metastasis and how microbes affect these processes. Some bacteria have a potent ability to enhance epithelial-mesenchymal transition, a critical step in the metastatic cascade. Bacteria also can modify the microenvironment and the local immune profile at a metastatic site. Early targeted antibiotic therapy should be further investigated as a measure to prevent metastatic spread in the setting of bacterial infection.

Dissecting Tumor Growth: The Role of Cancer Stem Cells in Drug Resistance and Recurrence

Simple Summary

Cancer is one of the most debated problems all over the world. Cancer stem cells are considered responsible of tumor initiation, metastasis, drug resistance, and recurrence. This subpopulation of cells has been found into the tumor bulk and showed the capacity to self-renew, differentiate, up to generate a new tumor. In the last decades, several studies have been set on the molecular mechanisms behind their specific characteristics as the Wnt/β-catenin signaling, Notch signaling, Hedgehog signaling, transcription factors, etc. The most powerful part of CSCs is represented by the niches as “promoter” of their self-renewal and “protector” from the common oncological treatment as chemotherapy and radiotherapy. In our review article we highlighted the primary mechanisms involved in CSC tumorigenesis for the setting of further targets to control the metastatic process.

Abstract

Emerging evidence suggests that a small subpopulation of cancer stem cells (CSCs) is responsible for initiation, progression, and metastasis cascade in tumors. CSCs share characteristics with normal stem cells, i.e., self-renewal and differentiation potential, suggesting that they can drive cancer progression. Consequently, targeting CSCs to prevent tumor growth or regrowth might offer a chance to lead the fight against cancer. CSCs create their niche, a specific area within tissue with a unique microenvironment that sustains their vital functions. Interactions between CSCs and their niches play a critical role in regulating CSCs’ self-renewal and tumorigenesis. Differences observed in the frequency of CSCs, due to the phenotypic plasticity of many cancer cells, remain a challenge in cancer therapeutics, since CSCs can modulate their transcriptional activities into a more stem-like state to protect themselves from destruction. This plasticity represents an essential step for future therapeutic approaches. Regarding self-renewal, CSCs are modulated by the same molecular pathways found in normal stem cells, such as Wnt/β-catenin signaling, Notch signaling, and Hedgehog signaling. Another key characteristic of CSCs is their resistance to standard chemotherapy and radiotherapy treatments, due to their capacity to rest in a quiescent state. This review will analyze the primary mechanisms involved in CSC tumorigenesis, with particular attention to the roles of CSCs in tumor progression in benign and malignant diseases; and will examine future perspectives on the identification of new markers to better control tumorigenesis, as well as dissecting the metastasis process.

Multi-ligand modified PC@DOX-PA/EGCG micelles effectively inhibit the growth of ER+, PR+ or HER2+ breast cancer

Breast cancer is one of the most common cancers in the world with tumor heterogeneity. Currently, cancer treatment mainly relies on surgical intervention, chemotherapy, and radiotherapy, for which the side effects, drug resistance and cost need to be resolved. In this study, we develop a natural medicine targeted therapy system. Phosphatidylcholine (PC), doxorubicin (DOX), procyanidin (PA), and epigallocatechin gallate (EGCG) are assembled and PC@DOX-PA/EGCG nanoparticles (NPs) are obtained. In addition, the HER2, ER and PR ligands were grafted on the surface of the NPs to acquire the targeted nanoparticles NP-ER, NP-ER-HER2, and NP-ER-HER2-PR. The physicochemical properties of the nanoparticles were detected and it was found that the nanoparticles are spherical and less than 200 nm in diameter. Furthermore, in vitro and in vivo results indicate that the nanoparticles can target BT-474, MCF-7, EMT-6, and MDA-MB-231 breast cancer cells, effectively inhibiting the growth of the breast cancer cells. In short, this research will provide some strategies for the treatment of heterogeneous breast cancer.

The role of RNA processing and regulation in metastatic dormancy

Tumor dormancy is a major contributor to the lethality of metastatic disease, especially for cancer patients who develop metastases years-to-decades after initial diagnosis. Indeed, tumor cells can disseminate during early disease stages and persist in new microenvironments at distal sites for months, years, or even decades before initiating metastatic outgrowth. This delay between primary tumor remission and metastatic relapse is known as "dormancy," during which disseminated tumor cells (DTCs) acquire quiescent states in response to intrinsic (i.e., cellular) and extrinsic (i.e., microenvironmental) signals. Maintaining dormancy-associated phenotypes requires DTCs to activate transcriptional, translational, and post-translational mechanisms that engender cellular plasticity. RNA processing is emerging as an essential facet of cellular plasticity, particularly with respect to the initiation, maintenance, and reversal of dormancy-associated phenotypes. Moreover, dysregulated RNA processing, particularly that associated with alternative RNA splicing and expression of noncoding RNAs (ncRNAs), can occur in DTCs to mediate intrinsic and extrinsic metastatic dormancy. Here we review the pathophysiological impact of alternative RNA splicing and ncRNAs in promoting metastatic dormancy and disease recurrence in human cancers.

Reviewing cancer's biology: an eclectic approach

BACKGROUND

Cancer refers to a group of some of the worldwide most diagnosed and deadliest pathophysiological conditions that conquered researchers' attention for decades and yet begs for more questions for a full comprehension of its complex cellular and molecular pathology.

MAIN BODY

The disease conditions are commonly characterized by unrestricted cell proliferation and dysfunctional replicative senescence pathways. In fact, the cell cycle operates under the rigorous control of complex signaling pathways involving cyclins and cyclin-dependent kinases assumed to be specific to each phase of the cycle. At each of these checkpoints, the cell is checked essentially for its DNA integrity. Genetic defects observed in these molecules (i.e., cyclins, cyclin-dependent kinases) are common features of cancer cells. Nevertheless, each cancer is different concerning its molecular and cellular etiology. These could range from the genetic defects mechanisms and/or the environmental conditions favoring epigenetically harbored homeostasis driving tumorigenesis alongside with the intratumoral heterogeneity with respect to the model that the tumor follows.

CONCLUSIONS

This review is not meant to be an exhaustive interpretation of carcinogenesis but to summarize some basic features of the molecular etiology of cancer and the intratumoral heterogeneity models that eventually bolster anticancer drug resistance for a more efficient design of drug targeting the pitfalls of the models.

Therapeutic roles of mesenchymal stem cell-derived extracellular vesicles in cancer

Extracellular vesicles (EVs) are cell-derived membrane structures enclosing proteins, lipids, RNAs, metabolites, growth factors, and cytokines. EVs have emerged as essential intercellular communication regulators in multiple physiological and pathological processes. Previous studies revealed that mesenchymal stem cells (MSCs) could either support or suppress tumor progression in different cancers by paracrine signaling via MSC-derived EVs. Evidence suggested that MSC-derived EVs could mimic their parental cells, possessing pro-tumor and anti-tumor effects, and inherent tumor tropism. Therefore, MSC-derived EVs can be a cell-free cancer treatment alternative. This review discusses different insights regarding MSC-derived EVs' roles in cancer treatment and summarizes bioengineered MSC-derived EVs’ applications as safe and versatile anti-tumor agent delivery platforms. Meanwhile, current hurdles of moving MSC-derived EVs from bench to bedside are also discussed.

Quantitative analysis of metastatic breast cancer in mice using deep learning on cryo-image data

Cryo-imaging sections and images a whole mouse and provides ~ 120-GBytes of microscopic 3D color anatomy and fluorescence images, making fully manual analysis of metastases an onerous task. A convolutional neural network (CNN)-based metastases segmentation algorithm included three steps: candidate segmentation, candidate classification, and semi-automatic correction of the classification result. The candidate segmentation generated > 5000 candidates in each of the breast cancer-bearing mice. Random forest classifier with multi-scale CNN features and hand-crafted intensity and morphology features achieved 0.8645 ± 0.0858, 0.9738 ± 0.0074, and 0.9709 ± 0.0182 sensitivity, specificity, and area under the curve (AUC) of the receiver operating characteristic (ROC), with fourfold cross validation. Classification results guided manual correction by an expert with our in-house MATLAB software. Finally, 225, 148, 165, and 344 metastases were identified in the four cancer mice. With CNN-based segmentation, the human intervention time was reduced from > 12 to ~ 2 h. We demonstrated that 4T1 breast cancer metastases spread to the lung, liver, bone, and brain. Assessing the size and distribution of metastases proves the usefulness and robustness of cryo-imaging and our software for evaluating new cancer imaging and therapeutics technologies. Application of the method with only minor modification to a pancreatic metastatic cancer model demonstrated generalizability to other tumor models.

Transcriptomic Profiling Reveals Novel Candidate Genes and Signalling Programs in Breast Cancer Quiescence and Dormancy

Metastatic recurrence, the major cause of breast cancer mortality, is driven by reactivation of dormant disseminated tumour cells that are defined by mitotic quiescence and chemoresistance. The molecular mechanisms underpinning mitotic quiescence in cancer are poorly understood, severely limiting the development of novel therapies for removal of residual, metastasis-initiating tumour cells. Here, we present a molecular portrait of the quiescent breast cancer cell transcriptome across the four main breast cancer sub-types (luminal, HER2-enriched, basal-like and claudin-low) and identify a novel quiescence-associated 22-gene signature using an established lipophilic-dye (Vybrant^® DiD) retention model and whole-transcriptomic profiling (mRNA-Seq). Using functional association network analysis, we elucidate the molecular interactors of these signature genes. We then go on to demonstrate that our novel 22-gene signature strongly correlates with low tumoural proliferative activity, and with dormant disease and late metastatic recurrence (≥5 years after primary tumour diagnosis) in metastatic breast cancer in multiple clinical cohorts. These genes may govern the formation and persistence of disseminated tumour cell populations responsible for breast cancer recurrence, and therefore represent prospective novel candidates to inform future development of therapeutic strategies to target disseminated tumour cells in breast cancer, eliminate minimal residual disease and prevent metastatic recurrence.