Cancer stem cells and metastasis. Semin Cancer Biol. 2012;22:187-193. [PMID: 22774232 DOI: 10.1016/j.semcancer.2012.03.002]

A comprehensive look at the role of hyperlipidemia in promoting colorectal cancer liver metastasis

Colorectal cancer (CRC) is one of the most malignant cancers, and it tends to migrate to the liver and has a high mortality rate. Several mechanisms behind the metastasis of CRC have been identified, including hyperlipidemia. For example, hyperlipidemia can lead to enhanced stemness and neutrophil infiltration, which increases CRC metastasis. There are three primary aspects to the relationship between hyperlipidemia and CRC metastasis: hyperlipidemia (1) promotes the initial metastatic properties of CRC, (2) stimulates CRC cells to leave the vasculature, and (3) facilitates the development of CRC metastasis. In this study, we provide a comprehensive overview of the role that hyperlipidemia played in CRC metastasis to help reduce the mortality associated with CRC metastasis from the standpoint of metabolic. We also review cancer metastasis.

Above the Epitranscriptome: RNA Modifications and Stem Cell Identity

Sequence databases and transcriptome-wide mapping have revealed different reversible and dynamic chemical modifications of the nitrogen bases of RNA molecules. Modifications occur in coding RNAs and noncoding-RNAs post-transcriptionally and they can influence the RNA structure, metabolism, and function. The result is the expansion of the variety of the transcriptome. In fact, depending on the type of modification, RNA molecules enter into a specific program exerting the role of the player or/and the target in biological and pathological processes. Many research groups are exploring the role of RNA modifications (alias epitranscriptome) in cell proliferation, survival, and in more specialized activities. More recently, the role of RNA modifications has been also explored in stem cell biology. Our understanding in this context is still in its infancy. Available evidence addresses the role of RNA modifications in self-renewal, commitment, and differentiation processes of stem cells. In this review, we will focus on five epitranscriptomic marks: N6-methyladenosine, N1-methyladenosine, 5-methylcytosine, Pseudouridine (Ψ) and Adenosine-to-Inosine editing. We will provide insights into the function and the distribution of these chemical modifications in coding RNAs and noncoding-RNAs. Mainly, we will emphasize the role of epitranscriptomic mechanisms in the biology of naïve, primed, embryonic, adult, and cancer stem cells.

Increasing aggressiveness of patient-derived xenograft models of cervix carcinoma during serial transplantation

Four patient-derived xenograft (PDX) models (BK-12, ED-15, HL-16, LA-19) of carcinoma of the uterine cervix have been developed in our laboratory, and their stability during serial transplantation in vivo was investigated in this study. Two frozen cell stocks were established, one from xenografted tumors in passage 2 (early generation) and the other from xenografted tumors transplanted serially in mice for approximately two years (late generation), and the biology of late generation tumors was compared with that of early generation tumors. Late generation tumors showed higher incidence of lymph node metastases than early generation tumors in three models (ED-15, HL-16, LA-19), and the increased metastatic propensity was associated with increased tumor growth rate, increased microvascular density, and increased expression of angiogenesis-related and cancer stem cell-related genes. Furthermore, late generation tumors showed decreased fraction of pimonidazole-positive tissue (i.e., decreased fraction of hypoxic tissue) in two models (HL-16, LA-19) and decreased fraction of collagen-I-positive tissue (i.e., less extensive extracellular matrix) in two models (ED-15, HL-16). This study showed that serially transplanted PDXs may not necessarily mirror the donor patients’ diseases, and consequently, proper use of serially transplanted PDX models in translational cancer research requires careful molecular monitoring of the models.

Up-Regulation of PI 3-Kinases and the Activation of PI3K-Akt Signaling Pathway in Cancer Stem-Like Cells Through DNA Hypomethylation Mediated by the Cancer Microenvironment

Previously, we have succeeded in converting induced pluripotent stem cells (iPSCs) into cancer stem cells (CSCs) by treating the iPSCs with conditioned medium of Lewis lung carcinoma (LLC) cells. The converted CSCs, named miPS-LLCcm cells, exhibited the self-renewal, differentiation potential, and potential to form malignant tumors with metastasis. In this study, we further characterized miPS-LLCcm cells both in vivo and in vitro. The tumors formed by subcutaneous injection showed the structures with pathophysiological features consisting of undifferentiated and malignant phenotypes generally found in adenocarcinoma. Metastasis in the lung was also observed as nodule structures. Excising from the tumors, primary cultured cells from the tumor and the nodule showed self-renewal, differentiation potential as well as tumor forming ability, which are the essential characters of CSCs. We then characterized the epigenetic regulation occurring in the CSCs. By comparing the DNA methylation level of CG rich regions, the differentially methylated regions (DMRs) were evaluated in all stages of CSCs when compared with the parental iPSCs. In DMRs, hypomethylation was found superior to hypermethylation in the miPS-LLCcm cells and its derivatives. The hypo- and hypermethylated genes were used to nominate KEGG pathways related with CSC. As a result, several categories were defined in the KEGG pathways from which most related with cancers, significant and high expression of components was PI3K-AKT signaling pathway. Simultaneously, the AKT activation was also confirmed in the CSCs. The PI3K-Akt signaling pathway should be an important pathway for the CSCs established by the treatment with conditioned medium of LLC cells.

Interleukin-30/IL27p28 Shapes Prostate Cancer Stem-like Cell Behavior and Is Critical for Tumor Onset and Metastasization

Prostate cancer stem-like cells (PCSLC) are believed to be responsible for prostate cancer onset and metastasis. Autocrine and microenvironmental signals dictate PCSLC behavior and patient outcome. In prostate cancer patients, IL30/IL27p28 has been linked with tumor progression, but the mechanisms underlying this link remain mostly elusive. Here, we asked whether IL30 may favor prostate cancer progression by conditioning PCSLCs and assessed the value of blocking IL30 to suppress tumor growth. IL30 was produced by PCSLCs in human and murine prostatic intraepithelial neoplasia and displayed significant autocrine and paracrine effects. PCSLC-derived IL30 supported PCSLC viability, self-renewal and tumorigenicity, expression of inflammatory mediators and growth factors, tumor immune evasion, and regulated chemokine and chemokine receptor genes, primarily via STAT1/STAT3 signaling. IL30 overproduction by PCSLCs promoted tumor onset and development associated with increased proliferation, vascularization, and myeloid cell recruitment. Furthermore, it promoted PCSLC dissemination to lymph nodes and bone marrow by upregulating the CXCR5/CXCL13 axis, and drove metastasis to lungs through the CXCR4/CXCL12 axis. These mechanisms were drastically hindered by IL30 knockdown or knockout in PCSLCs. Collectively, these results mark IL30 as a key driver of PCSLC behavior. Targeting IL30 signaling may be a potential therapeutic strategy against prostate cancer progression and recurrence.Significance: IL30 plays an important role in regulating prostate cancer stem-like cell behavior and metastatic potential, therefore targeting this cytokine could hamper prostate cancer progression or recurrence. Cancer Res; 78(10); 2654-68. ©2018 AACR.

MtDNA depleted PC3 cells exhibit Warburg effect and cancer stem cell features

Reducing mtDNA content was considered as a critical step in the metabolism restructuring for cell stemness restoration and further neoplastic development. However, the connections between mtDNA depletion and metabolism reprograming-based cancer cell stemness in prostate cancers are still lack of studies. Here, we demonstrated that human CRPC cell line PC3 tolerated high concentration of the mtDNA replication inhibitor ethidium bromide (EtBr) and the mtDNA depletion triggered a universal metabolic remodeling process. Failure in completing that process caused lethal consequences. The mtDNA depleted (MtDP) PC3 cells could be steadily maintained in the special medium in slow cycling status. The MtDP PC3 cells contained immature mitochondria and exhibited Warburg effect. Furthermore, the MtDP PC3 cells were resistant to therapeutic treatments and contained greater cancer stem cell-like subpopulations: CD44+, ABCG2+, side-population and ALDH^bright. In conclusion, these results highlight the association of mtDNA content, mitochondrial function and cancer cell stemness features.

Multimodal targeting of tumor vasculature and cancer stem-like cells in sarcomas with VEGF-A inhibition, HIF-1α inhibition, and hypoxia-activated chemotherapy

Vascular endothelial growth factor A (VEGF-A) inhibition with pazopanib is an approved therapy for sarcomas, but likely results in compensatory pathways such as upregulation of hypoxia inducible factor 1α (HIF-1α). In addition, cancer stem-like cells can preferentially reside in hypoxic regions of tumors and be resistant to standard chemotherapies. In this study, we hypothesized that the combination of VEGF-A inhibition, HIF-1α inhibition, and hypoxia-activated chemotherapy with evofosfamide would be an effective multimodal strategy. Multimodal therapy was examined in one genetically engineered and two xenograft mouse models of sarcoma. In all three models, multimodal therapy showed greater efficacy than any single agent therapy or bimodality therapy in blocking tumor growth. Even after cessation of therapy, tumors treated with multimodal therapy remained relatively dormant for up to 2 months. Compared to the next best bimodality therapy, multimodal therapy caused 2.8-3.3 fold more DNA damage, 1.5-2.7 fold more overall apoptosis, and 2.3-3.6 fold more endothelial cell-specific apoptosis. Multimodal therapy also decreased microvessel density and HIF-1α activity by 85-90% and 79-89%, respectively, compared to controls. Sarcomas treated with multimodal therapy had 95-96% depletion of CD133(+) cancer stem-like ells compared to control tumors. Sarcoma cells grown as spheroids to enrich for CD133(+) cancer stem-like cells were more sensitive than monolayer cells to multimodal therapy in terms of DNA damage and apoptosis, especially under hypoxic conditions. Thus multimodal therapy of sarcomas with VEGF-A inhibition, HIF-1α inhibition, and hypoxia-activated chemotherapy effectively blocks sarcoma growth through inhibition of tumor vasculature and cancer stem-like cells.

Expression of Cancer Stem Cell Marker CD44 and Its Polymorphisms in Patients with Chronic Gastritis, Precancerous Gastric Lesion, and Gastric Cancer: A Cross-Sectional Multicenter Study in Thailand

Here we investigated CD44 protein expression and its polymorphisms in patients with chronic gastritis, precancerous gastric lesions, and gastric cancer; and we evaluated our result with the risk of CD44 protein expression and clinicopathological characteristics. Our results obtained by analyzing 162 gastric cancer patients, 125 chronic gastritis, and 165 precancerous gastric lesions from three study centers in Thailand showed that CD44 expression was significantly higher in patients with precancerous gastric lesions and gastric cancer while patients with chronic gastritis were negative for CD44 staining (p = 0.036). We further observed the significant association of variant genotype; gastric cancer patients carrying AG or GG of CD44 rs187116 had more increased risk of CD44 expression than wild-type (WT) carriers (AG: odds ratio (OR) = 5.67; 95% CI = 1.57-7.23; p = 0.024 and GG: OR = 8.32; 95% CI = 2.94-11.42; p = 0.016), but no significant difference in the risk of CD44 expression due to polymorphism in patients with precancerous gastric lesions. Our results suggested that CD44 expression could be used as a marker for the prediction of gastric cancer development, particularly in patients with precancerous gastric lesions carrying AG or GG, who were selected to surveillance follow-up for gastric cancer prevention.

Identification of Key Genes in Colorectal Cancer Regulated by miR-34a

Background

The aim of this study was to screen the molecular targets of miR-34a in colorectal cancer (CRC) and construct the regulatory network, to gain more insights to the pathogenesis of CRC.

Material/Methods

The microarray data of CRC samples and normal samples (GSE4988), as well as CRC samples transformed with miR-34a and non-transfected CRC samples (GSE7754), were downloaded from the Gene Expression Omnibus (GEO) database. The differently expressed genes (DEGs) were identified via the LIMMA package in R language. The Database for Annotation, Visualization and Integrated Discovery (DAVID) was used to identify significant Gene Ontology (GO) terms and pathways in DEGs. The targets of miR-34a were obtained via the miRWalk database, and then the overlaps between them were selected out to construct the regulatory network of miR-34a in CRC using the Cytoscape software.

Results

A total of 392 DEGs were identified in CRC samples compared with normal samples, including 239 upregulated genes and 153 downregulated ones. These DEGs were enriched in 75 GO terms and one Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. At the same time, 332 DEGs (188 upregulated and 144 downregulated) were screened out between miR-34a transformed CRC and miR-34a non-transfected CRC samples and they were enriched in 20 GO terms and eight KEGG pathways. Six overlapped genes were identified in two DEGs groups. There were 1,668 targets of miR-34a obtained via the miRWalk database, among which 21 were identified differently expressed in miR-34a transformed CRC samples compared with miR-34a non-transfected CRC samples. Two regulatory networks of miR-34a in CRC within these two groups of overlapped genes were constructed respectively.

Conclusions

Pathways related to cell cycle, DNA replication, oocyte meiosis, and pyrimidine metabolism might play critical roles in the progression of CRC. Several genes such as SERPINE1, KLF4, SEMA4B, PPARG, CDC45, and KIAA0101 might be the targets of miR-34a and the potential therapeutic targets of CRC.

Piperlongumine inhibits cancer stem cell properties and regulates multiple malignant phenotypes in oral cancer

Piperlongumine (PL), a natural product of Piper longum, inhibits multiple malignant phenotypes. Therefore, the present study examined whether PL suppresses cancer stemness in oral cancer. The cellular effects of PL were determined by examining alterations in tumor sphere formation, cell migration, invasion, proliferation ability, chemosensitivity and radiosensitivity. Reverse transcription-quantitative polymerase chain reaction analysis and western blotting were performed in order to determine molecular expression levels. The present study revealed that PL inhibited cancer stem cell-forming ability and suppressed the expression of the stemness-related transcription factors SRY-Box 2, POU class 5 homeobox 1, and Nanog homeobox. However, it increased the expression of the differentiation marker cytokeratin 18. PL also suppressed cell migration and invasion, resulting in the elimination of the epithelial-mesenchymal transition. Furthermore, PL increased chemo- and radiosensitivity and suppressed tumor growth in vitro and in vivo. The results of the present study suggested that PL inhibits malignant phenotypes via the suppression of cancer stemness in oral cancer. Thus, PL may serve as an effective therapeutic agent for oral cancer.

Role of ALDH1 in the prognosis of esophageal cancer and its relationship with tumor microenvironment

Aldehyde dehydrogenase 1 (ALDH1) is associated with tumorigenesis, and significantly increased in cancer stem-like cells. In the present study, the role of ALDH1 in esophageal squamous cell carcinoma (ESCC) was investigated. We retrospectively analyzed the clinical outcomes of 148 ESCC and examined its correlation with ALDH1 levels. Furthermore, we preformed cellular and animal experiments to investigate the role of ALDH1 in tumor progression and microenvironment. Our data revealed that ALDH1 staining was positively linked to a higher clinical stage, higher loco-regional failure rate, and shorter survival time. Furthermore, there was a positive link between ALDH1 expression and IL-6 signaling according to the data of clinical specimens and cellular experiments. Using animal model, ALDH1-positive tumors were associated with aggressive tumor growth, increased IL-6, augmented epithelial-mesenchymal transition (EMT), and activation of myeloid-derived suppressor cells (MDSCs). Blockade of COX-2 attenuated the aggressive tumor growth of ALDH1-positive cancer cells. In conclusion, our findings suggested that ALDH1 played an important role in tumor aggressiveness and associated with a tumor-promoting microenvironment in esophageal cancer. Directly targeting ALDH1 or using a COX-2 inhibitor could be a promising strategy for the treatment of ESCC.

Intratumor heterogeneity predicts metastasis of triple-negative breast cancer

Even with the identical clinicopathological features, the ability for metastasis is vastly different among triple-negative breast cancer (TNBC) patients. Intratumor heterogeneity (ITH), which is common in breast cancer, may be a key mechanism leading to the tumor progression. In this study, we studied whether a quantitative genetic definition of ITH can predict clinical outcomes in patients with TNBC. We quantified ITH by calculating Shannon index, a measure of diversity in a population, based on Myc, epidermal growth factor receptor/centromeric probe 7 (EGFR/CEP7) and cyclin D1/centromeric probe 11 (CCND1/CEP11) copy number variations (CNVs) in 300 cells at three different locations of a tumor. Among 75 TNBC patients, those who developed metastasis had significantly higher ITH, that is Shannon indices of EGFR/CEP7 and CCND1/CEP11 CNVs. Higher Shannon indices of EGFR/CEP7 and CCND1/CEP11 CNVs were significantly associated with the development of metastasis and were predictive of significantly worse metastasis-free survival (MFS). Regional heterogeneity, defined as the difference in copy numbers of Myc, EGFR or CCND1 at different locations, was found in 52 patients. However, the presence of regional heterogeneity did not correlate with metastasis or MFS. Our findings demonstrate that higher ITH of EGFR/CEP7 and CCND1/CEP11 CNVs is predictive of metastasis and is associated with significantly worse MFS in TNBC patients, suggesting that ITH is a very promising novel prognostic factor in TNBC.

Metabolic reprogramming is associated with flavopiridol resistance in prostate cancer DU145 cells

Flavopiridol (FP) is a pan-cyclin dependent kinase inhibitor, which shows strong efficacy in inducing cancer cell apoptosis. Although FP is potent against most cancer cells in vitro, unfortunately it proved less efficacious in clinical trials in various aggressive cancers. To date, the molecular mechanisms of the FP resistance are mostly unknown. Here, we report that a small fraction human prostate cancer DU145 cells can survive long-term FP treatment and emerge as FP-resistant cells (DU145FP). These DU145FP cells show accumulated mitochondrial lesions with stronger glycolytic features, and they proliferate in slow-cycling and behave highly migratory with strong anti-apoptotic potential. In addition, the cells are less sensitive to cisplatin and docetaxel-induced apoptotic pressure, and over-express multiple stem cell associated biomarkers. Our studies collectively uncover for the first time that FP-resistant prostate cancer cells show metabolic remodeling, and the metabolic plasticity might be required for the FP resistance-associated cancer cell stemness up-regulation.

Antagonizing miR-455-3p inhibits chemoresistance and aggressiveness in esophageal squamous cell carcinoma

Background

The plasticity of cancer stem cells (CSCs)/tumor-initiating cells (T-ICs) suggests that multiple CSC/T-IC subpopulations exist within a tumor and that multiple oncogenic pathways collaborate to maintain the CSC/T-IC state. Here, we aimed to identify potential therapeutic targets that concomitantly regulate multiple T-IC subpopulations and CSC/T-IC-associated pathways.

Methods

A chemoresistant patient-derived xenograft (PDX) model of human esophageal squamous cell carcinoma (ESCC) was employed to identify microRNAs that contribute to ESCC aggressiveness. The oncogenic effects of microRNA-455-3p (miR-455-3p) on ESCC chemoresistance and tumorigenesis were examined by in vivo and in vitro chemoresistance, tumorsphere formation, side-population, and in vivo limiting dilution assays. The roles of miR-455-3p in activation of the Wnt/β-catenin and transforming growth factor-β (TGF-β)/Smad pathways were determined by luciferase and RNA immunoprecipitation assays.

Results

We found that miR-455-3p played essential roles in ESCC chemoresistance and tumorigenesis. Treatment with a miR-455-3p antagomir dramatically chemosensitized ESCC cells and reduced the subpopulations of CD90⁺ and CD271⁺ T-ICs via deactivation of multiple stemness-associated pathways, including Wnt/β-catenin and TGF-β signaling. Importantly, miR-455-3p exhibited aberrant upregulation in various human cancer types, and was significantly associated with decreased overall survival of cancer patients.

Conclusions

Our results demonstrate that miR-455-3p functions as an oncomiR in ESCC progression and may provide a potential therapeutic target to achieve better clinical outcomes in cancer patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-017-0669-9) contains supplementary material, which is available to authorized users.

Reduction in Migratory Phenotype in a Metastasized Breast Cancer Cell Line via Downregulation of S100A4 and GRM3

To investigate phenotypic and genotypic alterations before and after bone metastasis, we conducted genome-wide mRNA profiling and DNA exon sequencing of two cell lines (TMD and BMD) derived from a mouse xenograft model. TMD cells were harvested from the mammary fat pad after transfecting MDA-MB-231 breast cancer cells, while BMD cells were isolated from the metastasized bone. Compared to BMD cells, TMD cells exhibited higher cellular motility. In contrast, BMD cells formed a spheroid with a smoother and more circular surface when co-cultured with osteoblasts. In characterizing mRNA expression using principal component analysis, S100 calcium-binding protein A4 (S100A4) was aligned to a principal axis associated with metastasis. Partial silencing of S100A4 suppressed migratory capabilities of TMD cells, while Paclitaxel decreased the S100A4 level and reduced TMD’s cellular motility. DNA mutation analysis revealed that the glutamate metabotropic receptor 3 (GRM3) gene gained a premature stop codon in BMD cells, and silencing GRM3 in TMD cells altered their spheroid shape closer to that of BMD cells. Collectively, this study demonstrates that metastasized cells are less migratory due in part to the post-metastatic downregulation of S100A4 and GRM3. Targeting S100A4 and GRM3 may help prevent bone metastasis.

Label retention and stem cell marker expression in the developing and adult prostate identifies basal and luminal epithelial stem cell subpopulations

BACKGROUND

Prostate cancer is the second most frequent cancer among males worldwide, and most patients with metastatic disease eventually develop therapy-resistant disease. Recent research has suggested the existence of cancer stem-like cells, and that such cells are behind the therapy resistance and progression.

METHODS

Here, we have taken advantage of the relatively quiescent nature of stem cells to identify the slow-cycling label-retaining stem cell (LRC) populations of the prostate gland. Mice were pulsed with bromodeoxyuridine (BrdU) during prostate organogenesis, and the LRC populations were then identified and characterized in 5-day-old and in 6-month-old adult animals using immunohistochemistry and immunofluorescence.

RESULTS

Quantification of LRCs in the adult mouse prostate showed that epithelial LRCs were significantly more numerous in prostatic ducts (3.7 ± 0.47% SD) when compared to the proximal (1.4 ± 0.83%) and distal epithelium (0.48 ± 0.08%) of the secretory lobes. LRCs were identified in both the basal and epithelial cell layers of the prostate, and LRCs co-expressed several candidate stem cell markers in a developmental and duct/acini-specific manner, including Sca-1, TROP-2, CD133, CD44, c-kit, and the novel prostate progenitor marker cytokeratin-7. Importantly, a significant proportion of LRCs were localized in the luminal cell layer, the majority in ducts and the proximal prostate, that co-expressed high levels of androgen receptor in the adult prostate.

CONCLUSIONS

Our results suggest that there are separate basal and luminal stem cell populations in the prostate, and they open up the possibility that androgen receptor-expressing luminal stem-like cells could function as cancer-initiating and relapse-responsible cells in prostate cancer.

A liquid biopsy-based method for the detection and quantification of circulating tumor cells in surgical osteosarcoma patients

A method for the enumeration and quantification of osteosarcoma (OS) circulating tumor cells (CTCs) is currently not available. A correlation between the number of CTCs and progression-free survival (PFS) has been established for other cancers, but not for OS CTCs. A method was therefore developed for CTC quantification in OS and validated in a prospective cohort of surgical patients with primary and recurrent/metastatic OS (N=23). Human OS cells, acting as CTCs, were enumerated from spiked human peripheral blood (PB) following erythrocyte and leukocyte depletion. The OS cells were quantified microscopically based on aneuploidy and a CK18-/CD45- phenotype. Aneuploidy was assayed by fluorescence in situ hybridization (FISH) using fluorescence-labeled alpha-satellite probes for the centromeres of chromosome (CEP 8). CK18 and CD45 phenotyping was performed with immunocytochemistry. HOS cells in spiked PB could be effectively retrieved with the FISH-based enumeration method, which was subsequently employed in an OS patient cohort. PB of recurrent/metastatic OS patients contained more CTCs than the PB of primary OS patients. OS patients with ≥2 CTCs per 7.5 ml of PB had worse PFS than patients whose PB contained <2 CTCs. In 2 cases, CTCs were present in PB of OS patients with negative X-ray and chest CT scans. In conclusion, our method was able to quantitate CTCs in liquid biopsies of OS patients. The number of CTCs has diagnostic and prognostic value.

Co-delivery of all-trans-retinoic acid enhances the anti-metastasis effect of albumin-bound paclitaxel nanoparticles

Co-delivery of the cell differentiation agent ATRA significantly enhances the anti-metastasis effect of nanoparticle albumin-bound paclitaxel in breast cancer treatment.

The role of cancer stem cells in tumor heterogeneity and resistance to therapy

Cancer is a heterogenous disease displaying marked inter- and intra-tumoral diversity. The existence of cancer stem cells (CSCs) has been experimentally demonstrated in a number of cancer types as a subpopulation of tumor cells that drives the tumorigenic and metastatic properties of the entire cancer. Thus, eradication of the CSC population is critical for the complete ablation of a tumor. This is, however, confounded by the inherent resistance of CSCs to standard anticancer therapies, eventually leading to the outgrowth of resistant tumor cells and relapse in patients. The cellular mechanisms of therapy resistance in CSCs are ascribed to several factors including a state of quiescence, an enhanced DNA damage response and active repair mechanisms, up-regulated expression of drug efflux transporters, as well as the activation of pro-survival signaling pathways and inactivation of apoptotic signaling. Understanding the mechanisms underlying the acquisition of resistance to therapy may hold the key to targeting the CSC population.

Potential therapeutic effect of epigenetic therapy on treatment-induced neuroendocrine prostate cancer

Although adenocarcinomas of the prostate are relatively indolent, some patients with advanced adenocarcinomas show recurrence of treatment-induced neuroendocrine prostate cancer, which is highly aggressive and lethal. Detailed biological features of treatment-induced neuroendocrine prostate cancer have not been characterized owing to limited biopsies/resections and the lack of a cellular model. In this study, we used a unique cellular model (LNCaP/NE1.8) to investigate the potential role of cancer stem cells in treatment-induced neuroendocrine prostate cancer with acquired resistance to hormonal therapy and chemotherapy. We also studied the role of cancer stem cells in enhancing invasion in treatment-induced neuroendocrine prostate cancer cells that recurred after long-term androgen-ablation treatment. Using an in vitro system mimicking clinical androgen-ablation, our results showed that the neuroendocrine-like subclone NE1.8 cells were enriched with cancer stem cells. Compared to parental prostate adenocarcinoma LNCaP cells, NE1.8 cells are more resistant to androgen deprivation therapy and chemotherapeutic agents and show increased cancer cell invasiveness. Results from this study also suggest a potential epigenetic therapeutic strategy using suberoylanilide hydroxamic acid, a histone deacetylase inhibitor, as a chemotherapeutic agent for therapy-resistant treatment-induced neuroendocrine prostate cancer cells to minimize the risk of prostate cancer recurrence and metastasis.

Epigenetic therapy potential of suberoylanilide hydroxamic acid on invasive human non-small cell lung cancer cells

Metastasis is the reason for most cancer death, and a crucial primary step for cancer metastasis is invasion of the surrounding tissue, which may be initiated by some rare tumor cells that escape the heterogeneous primary tumor. In this study, we isolated invasive subpopulations of cancer cells from human non-small cell lung cancer (NSCLC) H460 and H1299 cell lines, and determined the gene expression profiles and the responses of these invasive cancer cells to treatments of ionizing radiation and chemotherapeutic agents. The subpopulation of highly invasive NSCLC cells showed epigenetic signatures of epithelial-mesenchymal transition, cancer cell stemness, increased DNA damage repair and cell survival signaling. We also investigated the epigenetic therapy potential of suberoylanilide hydroxamic acid (SAHA) on invasive cancer cells, and found that SAHA suppresses cancer cell invasiveness and sensitizes cancer cells to treatments of IR and chemotherapeutic agents. Our results provide guidelines for identification of metastatic predictors and for clinical management of NSCLC. This study also suggests a beneficial clinical potential of SAHA as a chemotherapeutic agent for NSCLC patients.

The DNA Damage Transducer RNF8 Facilitates Cancer Chemoresistance and Progression through Twist Activation

Twist has been shown to cause treatment failure, cancer progression, and cancer-related death. However, strategies that directly target Twist are not yet conceivable. Here we reveal that K63-linked ubiquitination is a crucial regulatory mechanism for Twist activation. Through an E3 ligase screen and biochemical studies, we unexpectedly identified that RNF8 functions as a direct Twist activator by triggering K63-linked ubiquitination of Twist. RNF8-promoted Twist ubiquitination is required for Twist localization to the nucleus for subsequent EMT and CSC functions, thereby conferring chemoresistance. Our histological analyses showed that RNF8 expression is upregulated and correlated with disease progression, EMT features, and poor patient survival in breast cancer. Moreover, RNF8 regulates cancer cell migration and invasion and cancer metastasis, recapitulating the effect of Twist. Together, our findings reveal a previously unrecognized tumor-promoting function of RNF8 and provide evidence that targeting RNF8 is an appealing strategy to tackle tumor aggressiveness and treatment resistance.

Poly lactic-co-glycolic acid controlled delivery of disulfiram to target liver cancer stem-like cells

Disulfiram (DS), an anti-alcoholism drug, shows very strong cytotoxicity in many cancer types. However its clinical application in cancer treatment is limited by the very short half-life in the bloodstream. In this study, we developed a poly lactic-co-glycolic acid (PLGA)-encapsulated DS protecting DS from the degradation in the bloodstream. The newly developed DS-PLGA was characterized. The DS-PLGA has very satisfactory encapsulation efficiency, drug-loading content and controlled release rate in vitro. PLGA encapsulation extended the half-life of DS from shorter than 2minutes to 7hours in serum. In combination with copper, DS-PLGA significantly inhibited the liver cancer stem cell population. CI-isobologram showed a remarkable synergistic cytotoxicity between DS-PLGA and 5-FU or sorafenib. It also demonstrated very promising anticancer efficacy and antimetastatic effect in liver cancer mouse model. Both DS and PLGA are FDA approved products for clinical application. Our study may lead to repositioning of DS into liver cancer treatment.

Quantifying the landscape and kinetic paths for epithelial-mesenchymal transition from a core circuit

Epithelial-mesenchymal transition (EMT), as a crucial process in embryonic development and cancer metastasis, has been investigated extensively. However, how to quantify the global stability and transition dynamics for EMT under fluctuations remains to be elucidated. Starting from a core EMT genetic circuit composed of three key proteins or microRNAs (microRNA-200, ZEB and SNAIL), we uncovered the potential landscape for the EMT process. Three attractors emerge from the landscape, which correspond to epithelial, mesenchymal and partial EMT states respectively. Based on the landscape, we analyzed two important quantities of the EMT system: the barrier heights between different basins of attraction that describe the degree of difficulty for EMT or backward transition, and the mean first passage time (MFPT) that characterizes the kinetic transition rate. These quantities can be harnessed as measurements for the stability of cell types and the degree of difficulty of transitions between different cell types. We also calculated the minimum action paths (MAPs) by path integral approaches. The MAP delineates the transition processes between different cell types quantitatively. We propose two different EMT processes: a direct EMT from E to P, and a step-wise EMT going through an intermediate state, depending on different extracellular environments. The landscape and kinetic paths we acquired offer a new physical and quantitative way for understanding the mechanisms of EMT processes, and indicate the possible roles for the intermediate states.

Transposon mutagenesis identifies genes and cellular processes driving epithelial-mesenchymal transition in hepatocellular carcinoma

Epithelial-mesenchymal transition (EMT) is thought to contribute to metastasis and chemoresistance in patients with hepatocellular carcinoma (HCC), leading to their poor prognosis. The genes driving EMT in HCC are not yet fully understood, however. Here, we show that mobilization of Sleeping Beauty (SB) transposons in immortalized mouse hepatoblasts induces mesenchymal liver tumors on transplantation to nude mice. These tumors show significant down-regulation of epithelial markers, along with up-regulation of mesenchymal markers and EMT-related transcription factors (EMT-TFs). Sequencing of transposon insertion sites from tumors identified 233 candidate cancer genes (CCGs) that were enriched for genes and cellular processes driving EMT. Subsequent trunk driver analysis identified 23 CCGs that are predicted to function early in tumorigenesis and whose mutation or alteration in patients with HCC is correlated with poor patient survival. Validation of the top trunk drivers identified in the screen, including MET (MET proto-oncogene, receptor tyrosine kinase), GRB2-associated binding protein 1 (GAB1), HECT, UBA, and WWE domain containing 1 (HUWE1), lysine-specific demethylase 6A (KDM6A), and protein-tyrosine phosphatase, nonreceptor-type 12 (PTPN12), showed that deregulation of these genes activates an EMT program in human HCC cells that enhances tumor cell migration. Finally, deregulation of these genes in human HCC was found to confer sorafenib resistance through apoptotic tolerance and reduced proliferation, consistent with recent studies showing that EMT contributes to the chemoresistance of tumor cells. Our unique cell-based transposon mutagenesis screen appears to be an excellent resource for discovering genes involved in EMT in human HCC and potentially for identifying new drug targets.

Isoprenaline Induces Periostin Expression in Gastric Cancer

PURPOSE

Periostin mediates critical steps in gastric cancer and is involved in various signaling pathways. However, the roles of periostin in promoting gastric cancer metastasis are not clear. The aim of this study was to investigate the relevance between periostin expression and gastric cancer progression and the role of stress-related hormones in the regulation of cancer development and progression.

MATERIALS AND METHODS

Normal, cancerous and metastatic gastric tissues were collected from patients diagnosed with advanced gastric cancer. The in vivo expression of periostin was evaluated by in situ hybridization and immunofluorescent staining. Meanwhile, human gastric adenocarcinoma cell lines MKN-45 and BGC-803 were used to detect the in vitro expression of periostin by using quantitative real-time polymerase chain reaction (PCR) and western blotting.

RESULTS

Periostin is expressed in the stroma of the primary gastric tumors and metastases, but not in normal gastric tissue. In addition, we observed that periostin is located mainly in pericryptal fibroblasts, but not in the tumor cells, and strongly correlated to the expression of α-smooth muscle actin (SMA). Furthermore, the distribution patterns of periostin were broader as the clinical staging of tumors progressed. We also identified a role of stress-related signaling in promoting cancer development and progression, and found that isoprenaline upregulated expression levels of periostin in gastric cancer cells.

CONCLUSION

These findings suggest that the distribution pattern of periostin was broader as the clinical staging of the tumor progressed and found that isoprenaline upregulated expression levels of periostin in gastric cancer cells.

Stem cell technology in breast cancer: current status and potential applications

Breast cancer, the leading cause of cancer among females, is supported by the presence of a rare subset of undifferentiated cells within the tumor, identified as breast cancer stem cells (BCSCs). BCSCs underlie the mechanisms of tumor initiation and sustenance and are implicated in the dissemination of the primary tumor to metastatic sites, as they have been found circulating in the blood of breast cancer patients. The discovery of BCSCs has generated a great amount of interest among the scientific community toward their isolation, molecular characterization, and therapeutic targeting. In this review, after summarizing the literature on molecular characterization of BCSCs and methodologies used for their isolation, we will focus on recent data supporting their molecular and functional heterogeneity. Additionally, following a synopsis of the latest approaches for BCSC targeting, we will specifically emphasize on the therapeutic use of naïve or engineered normal stem cells in the treatment of breast cancer and present contradictory findings challenging their safety.

Gastric cancer stem cells: evidence, potential markers, and clinical implications

Gastric cancer is a significant global health problem. It is the fifth most common cancer and third leading cause of cancer-related death worldwide (Torre et al. in CA Cancer J Clin 65(2):87-108, 2015). Despite advances in treatment, overall prognosis remains poor, due to tumour relapse and metastasis. There is an urgent need for novel therapeutic approaches to improve clinical outcomes in gastric cancer. The cancer stem cell (CSC) model has been proposed to explain the high rate of relapse and subsequent resistance of cancer to current systemic treatments (Vermeulen et al. in Lancet Oncol 13(2):e83-e89, 2012). CSCs have been identified in many solid malignancies, including gastric cancer, and have significant clinical implications, as targeting the CSC population may be essential in preventing the recurrence and spread of a tumour (Dewi et al. in J Gastroenterol 46(10):1145-1157, 2011). This review seeks to summarise the current evidence for CSC in gastric cancer, with an emphasis on candidate CSC markers, clinical implications, and potential therapeutic approaches.

All-trans retinoic acids induce differentiation and sensitize a radioresistant breast cancer cells to chemotherapy

Background

Radiotherapy is of critical importance in the treatment of breast cancer. However, not all patients derive therapeutic benefit and some breast cancers are resistant to the treatment, and are thus evidenced with prospective distant metastatic spread and local recurrence. In this study, we investigated the potential therapeutic effects of all-trans retinoic acid (ATRA) on radiation-resistant breast cancer cells and the associated invasiveness.

Methods

The MCF7/C6 cells with gained radiation resistance after a long term treatment with fractionated ionizing radiation were derived from human breast cancer MCF7 cell line, and are enriched with cells expressing putative breast cancer stem cell biomarker CD44⁺/CD24^-/low/ALDH⁺. The enhanced invasiveness and the acquired resistances to chemotherapeutic treatments of MCF7/C6 cells were measured, and potential effects of all-trans retinoic acid (ATRA) on the induction of differentiation, invasion and migration, and on the sensitivities to chemotherapies in MCF7/C6 cells were investigated.

Results

MCF7/C6 cells are with enrichment of cancer stem-cell like cells with positive staining of CD44⁺/CD24^-/low, OCT3/4 and NANOG. MCF7/C6 cells showed an increased tumoregensis potential and enhanced aggressiveness of invasion and migration. Treatment with ATRA induces the differentiation in MCF7/C6 cells, resulting in reduced invasiveness and migration, and increased sensitivity to Epirubincin treatment.

Conclusion

Our study suggests a potential clinic impact for ATRA as a chemotherapeutic agent for treatment of therapy-resistant breast cancer especially for the metastatic lesions. The study also provides a rationale for ATRA as a sensitizer of Epirubincin, a first-line treatment option for breast cancer patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-016-1088-y) contains supplementary material, which is available to authorized users.

Autologous melanoma cell vaccine using monocyte-derived dendritic cells (NBS20/eltrapuldencel-T)

Targeted therapy and immunotherapy have revolutionized the treatment of advanced melanoma. Despite recent advances, lack of long-term efficacy from targeted therapy and serious immune-related toxicity are major concerns. There is unmet need for 'durable' and 'safe' treatment options for advanced melanoma. Cancer vaccine therapy in melanoma has been investigated for many years with modest clinical efficacy. More recently, dendritic cell-based vaccine products have become available for clinical use and have been the focus of investigation. CLBS20 (NBS20/eltrapuldencel-T) is a novel dendritic cell-based vaccine product that has shown promising results in early phase trials in advanced melanoma. This cancer vaccine approach could play an important role in providing a sustainable survival benefit, targeting cancer cells themselves and avoiding off-target immune-related toxicity.

Combined Effects of Suberoylanilide Hydroxamic Acid and Cisplatin on Radiation Sensitivity and Cancer Cell Invasion in Non-Small Cell Lung Cancer

Lung cancer is a leading cause of cancer-related mortality worldwide, and concurrent chemoradiotherapy has been explored as a therapeutic option. However, the chemotherapeutic agents cannot be administered for most patients at full doses safely with radical doses of thoracic radiation, and further optimizations of the chemotherapy regimen to be given with radiation are needed. In this study, we examined the effects of suberoylanilide hydroxamic acid (SAHA) and cisplatin on DNA damage repairs, and determined the combination effects of SAHA and cisplatin on human non-small cell lung cancer (NSCLC) cells in response to treatment of ionizing radiation (IR), and on tumor growth of lung cancer H460 xenografts receiving radiotherapy. We also investigated the potential differentiation effect of SAHA and its consequences on cancer cell invasion. Our results showed that SAHA and cisplatin compromise distinct DNA damage repair pathways, and treatment with SAHA enhanced synergistic radiosensitization effects of cisplatin in established NSCLC cell lines in a p53-independent manner, and decreased the DNA damage repair capability in cisplatin-treated primary NSCLC tumor tissues in response to IR. SAHA combined with cisplatin also significantly increased inhibitory effect of radiotherapy on tumor growth in the mouse xenograft model. In addition, SAHA can induce differentiation in stem cell-like cancer cell population, reduce tumorigenicity, and decrease invasiveness of human lung cancer cells. In conclusion, our data suggest a potential clinical impact for SAHA as a radiosensitizer and as a part of a chemoradiotherapy regimen for NSCLC. Mol Cancer Ther; 15(5); 842-53. ©2016 AACR.

Patient-derived xenograft models of squamous cell carcinoma of the uterine cervix

Patient-derived xenograft (PDX) models of cancer are considered to reflect the biology and treatment response of human tumors to a larger extent than xenograft models initiated from established cell lines. The characterization of a panel of four novel PDX models of cervical carcinoma of the uterine cervix is described in this communication. The outcome of treatment differed substantially among the donor patients, and the PDX models were found to mirror the histology, aggressiveness, and metastatic propensity of the donor patients' tumors. Two of the models (BK-12 and LA-19) were highly metastatic, one model (ED-15) was poorly metastatic, and one model (HL-16) was non-metastatic. The primary tumors of the two highly metastatic models showed high density of intratumoral lymphatics, whereas the other two models did not develop intratumoral lymphatics. The potential of the models to metastasize to lymph nodes was associated with high expression of both angiogenesis-related genes and cancer stem cell-related genes. The models may be highly valuable for studying mechanisms linking lymph node metastasis to lymphangiogenesis, hemangiogenesis, and the presence of cancer stem cells.

Low concentrations of 5-aza-2'-deoxycytidine induce breast cancer stem cell differentiation by triggering tumor suppressor gene expression

Background

Breast cancer stem cells (BCSCs) are considered the cause of tumor growth, multidrug resistance, metastasis, and recurrence. Therefore, differentiation therapy to reduce self-renewal of BCSCs is a promising approach. We have examined the effects of 5-aza-2′-deoxycytidine (DAC) on BCSC differentiation.

Materials and methods

BCSCs were treated with a range of DAC concentrations from 0.625 to 100 µM. The differentiation status of DAC-treated BCSCs was graded by changes in cell proliferation, CD44⁺CD24⁻ phenotype, expression of tumor suppressor genes, including BRCA1, BRCA2, p15, p16, p53, and PTEN, and antitumor drug resistance.

Results

DAC treatment caused significant BCSC differentiation. BCSCs showed a 15%–23% reduction in proliferation capacity, 3.0%–21.3% decrease in the expression of BCSC marker CD44⁺/CD24⁻, activation of p53 expression, and increased p15, p16, BRCA1, and BRCA2 expression. Concentrations of DAC ranging from 0.625 to 40 µM efficiently induce cell cycle arrest in S-phase. ABCG2, highly expressed in BCSCs, also decreased with DAC exposure. Of particular note, drug-sensitivity of BCSCs to doxorubicin, verapamil, and tamoxifen also increased 1.5-, 2.0-, and 3.7-fold, respectively, after pretreatment with DAC.

Conclusion

DAC reduced breast cancer cell survival and induced differentiation through reexpression of tumor suppressor genes. These results indicate the potential of DAC in targeting specific chemotherapy-resistant cells within a tumor.

Androgen-glucocorticoid interactions in the era of novel prostate cancer therapy

Great strides have been made in the treatment of castration-resistant prostate cancer (CRPC) with the development of new antiandrogens (enzalutamide) and more potent androgen synthesis inhibitors (abiraterone) that have both improved patient outcomes. These new drugs have also helped unravel the complex biology of androgen-androgen receptor driven prostate cancer and brought into prominence various mechanisms triggering the development of drug resistance and tumour cell survival despite use of androgen deprivation therapy (ADT). The complex role of glucocorticoids in the treatment, management and progression of patients with CRPC is integral to these advances. Historically, glucocorticoid treatment has resulted in both subjective and objective responses in patients with advanced-stage prostate cancer. With the use of these new therapeutic agents, however, unexpected glucocorticoid-related mechanisms that can cause iatrogenic stimulation of prostate cancer growth have emerged, which might contribute to drug resistance and disease progression despite optimal ADT. For example, the upregulation of glucocorticoid receptors (GRs) during enzalutamide therapy results in glucocorticoid-GR-mediated regulation of androgen target genes, leading to escape from enzalutamide blockade. Thus, understanding the biological role of glucocorticoids in patients with prostate cancer is of major importance in the era of new and evolving antiandrogen therapies.

Beyond the histone tale: HP1α deregulation in breast cancer epigenetics

Heterochromatin protein 1α (HP1α) encoded from the CBX5-gene is an evolutionary conserved protein that binds histone H3 di- or tri-methylated at position lysine 9 (H3K9me2/3), a hallmark for heterochromatin, and has an essential role in forming higher order chromatin structures. HP1α has diverse functions in heterochromatin formation, gene regulation, and mitotic progression, and forms complex networks of gene, RNA, and protein interactions. Emerging evidence has shown that HP1α serves a unique biological role in breast cancer related processes and in particular for epigenetic control mechanisms involved in aberrant cell proliferation and metastasis. However, how HP1α deregulation plays dual mechanistic functions for cancer cell proliferation and metastasis suppression and the underlying cellular mechanisms are not yet comprehensively described. In this paper we provide an overview of the role of HP1α as a new sight of epigenetics in proliferation and metastasis of human breast cancer. This highlights the importance of addressing HP1α in breast cancer diagnostics and therapeutics.

The Presence of EpCAM(-)/CD49f(+) Cells in Breast Cancer Is Associated with a Poor Clinical Outcome

Purpose

It is well established that breast cancer stem cells (BCSCs) play an essential role in tumor invasion for both local and distant metastasis. The aim of this study was to establish whether BCSCs could act as a prognostic and clinical marker.

Methods

We analyzed tumor tissues from 161 breast cancer patients. Dual immunohistochemistry and immunofluorescence were performed on all the slides, and we analyzed the relationship between EpCAM^-/CD49f⁺ tumor cells and key clinical and prognostic factors.

Results

Univariate survival analysis using the Kaplan-Meier method showed that the presence of EpCAM^-/CD49f⁺ tumor cells in breast cancer was significantly associated with shorter disease-free survival (DFS) and overall survival (OS). Multivariate analysis showed that the presence of EpCAM^-/CD49f⁺ cells was associated with shorter DFS (p=0.010; hazard ratio [HR], 2.070) and OS (p=0.002; HR, 3.235). Tumors containing EpCAM^-/CD49f⁺ cells were also more likely to metastasize after initial surgery (p=0.048).

Conclusion

Our study suggests that breast tumors containing EpCAM^-/CD49f⁺ cells are more likely to undergo distant metastasis after initial surgery and are associated with a shorter DFS and OS.

Concise review: The obesity cancer paradigm: exploration of the interactions and crosstalk with adipose stem cells

With the recognition of obesity as a global health crisis, researchers have devoted greater effort to defining and understanding the pathophysiological molecular pathways regulating the biology of adipose tissue and obesity. Obesity, the excessive accumulation of adipose tissue due to hyperplasia and hypertrophy, has been linked to an increased incidence and aggressiveness of colon, hematological, prostate, and postmenopausal breast cancers. The increased morbidity and mortality of obesity-associated cancers have been attributed to higher levels of hormones, adipokines, and cytokines secreted by the adipose tissue. The increased amount of adipose tissue also results in higher numbers of adipose stromal/stem cells (ASCs). These ASCs have been shown to impact cancer progression directly through several mechanisms, including the increased recruitment of ASCs to the tumor site and increased production of cytokines and growth factors by ASCs and other cells within the tumor stroma. Emerging evidence indicates that obesity induces alterations in the biologic properties of ASCs, subsequently leading to enhanced tumorigenesis and metastasis of cancer cells. This review will discuss the links between obesity and cancer tumor progression, including obesity-associated changes in adipose tissue, inflammation, adipokines, and chemokines. Novel topics will include a discussion of the contribution of ASCs to this complex system with an emphasis on their role in the tumor stroma. The reciprocal and circular feedback loop between obesity and ASCs as well as the mechanisms by which ASCs from obese patients alter the biology of cancer cells and enhance tumorigenesis will be discussed.

USP44+ Cancer Stem Cell Subclones Contribute to Breast Cancer Aggressiveness by Promoting Vasculogenic Mimicry

Vasculogenic mimicry (VM), a newly defined pattern of tumor blood supply, describes the functional plasticity of aggressive cancer cells that form vascular networks. In our previous study, breast cancer stem cells (CSC) were shown to potentially participate in VM formation. In this study, breast CSCs presented centrosome amplification (CA) phenotype and ubiquitin-specific protease 44 (USP44) upregulation. USP44 expression contributed to the establishment of bipolar spindles in breast CSCs with supernumerary centrosomes by localizing at pole-associated centrosomes. The bipolar spindle patterns of breast CSCs with CA, including planar-like and apico-basal-like, functioned differently during the VM process of CSCs. Moreover, the ability of transendothelial migration in VM-forming cells was increased. In vivo experiment results showed that CSC xenografts presented linearly patterned programmed cell necrosis, which provided a spatial foundation for VM formation as well as angiogenesis. Breast CSCs further showed increased levels of IL6 and IL8. However, USP44 silencing induced spindle multipolarity, abated VM, reduced transendothelial migration, and consequently decreased IL6 and IL8 levels in breast CSCs. Finally, USP44(+) CSC subclones (ALDH1(+)/USP44(+)/IL6(+)/IL8(+)) were identified in breast cancer specimens through consecutive sections scanning. The subclones were related not only to CA, but also to VM. Statistical analysis suggested that USP44(+) CSC subclones could be used as an independent prognostic biomarker of poor clinical outcomes in patients with breast cancer. Collectively, the identification of USP44(+) CSC subclones may contribute to the prediction of VM formation and aggressive behavior. This study provides novel insights into the therapy for advanced breast cancer.