Common stemness regulators of embryonic and cancer stem cells

Increased insulin-like growth factor 1 production by polyploid adipose stem cells promotes growth of breast cancer cells

Background

Adipose-tissue stem cells (ASCs) are subject of intensive research since their successful use in regenerative therapy. The drawback of ASCs is that they may serve as stroma for cancer cells and assist tumor progression. It is disquieting that ASCs frequently undergo genetic and epigenetic changes during their in vitro propagation. In this study, we describe the polyploidization of murine ASCs and the accompanying phenotypical, gene expressional and functional changes under long term culturing.

Methods

ASCs were isolated from visceral fat of C57BL/6 J mice, and cultured in vitro for prolonged time. The phenotypical changes were followed by microscopy and flow cytometry. Gene expressional changes were determined by differential transcriptome analysis and changes in protein expression were shown by Western blotting. The tumor growth promoting effect of ASCs was examined by co-culturing them with 4 T1 murine breast cancer cells.

Results

After five passages, the proliferation of ASCs decreases and cells enter a senescence-like state, from which a proportion of cells escape by polyploidization. The resulting ASC line is susceptible to adipogenic, osteogenic and chondrogenic differentiation, and expresses the stem cell markers CD29 and Sca-1 on an upregulated level. Differential transcriptome analysis of ASCs with normal and polyploid karyotype shows altered expression of genes that are involved in regulation of cancer, cellular growth and proliferation. We verified the increased expression of Klf4 and loss of Nestin on protein level. We found that elevated production of insulin-like growth factor 1 by polyploid ASCs rendered them more potent in tumor growth promotion in vitro.

Conclusions

Our model indicates how ASCs with altered genetic background may support tumor progression.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4781-z) contains supplementary material, which is available to authorized users.

Non-Coding RNA Pvt1 Promotes Cancer Stem Cell-Like Traits in Nasopharyngeal Cancer via Inhibiting miR-1207

Nasopharyngeal carcinoma (NPC) is a kind of head-neck malignant tumor. lncRNA-PVT1 can promote the proliferation of carcinoma cells, and induce cells to have stem cell-like potentials. However, the function of PVT1 in NPC cells is not clear. The expressions of lncRNA-PVT1 and the expressions of the stem cell markers in NPC tissues or cell lines were investigated by qRT-PCR or western blot. The cell proliferation, and the ability of NPC cells to form spherical, clonal colonies were investigated by MTT assay, colony formation assay, and tumor-sphere formation assay. Cancer stem cells surface markers were detected by flow cytometry and western blot. PI3K/AKT signal activation in NPC cells was determined by western blot. PVT1 was significantly up-regulated in both NPC tissues and cell lines and associated with poor prognosis. PVT1 knockdown reduced NPC cells viability, clonogenicity, the cell surface CD44+/CD24- stem phenotype, and the expressions of the stem cell markers in NPC cells, including Oct4, c-Myc, SOX2, and ALDH. Furthermore, PVT1 negatively regulates the expression levels of miR-1207 in NPC cells and spheres cells, which is critical for NPC stemness. Knockdown of miR-1207 promoted stem phenotype and the expressions of the stem cell markers in NPC cells. Moreover, phosphor-PI3K (p-PI3K) and phosphor-AKT (p-AKT) were found to be down-regulated after PVT1 siRNAs transfection in NPC cells. And miR-1207 inhibitor transfection reversed the all the effects brought by PVT1 knockdown. Pvt1 promotes cancer stem cell-like properties in NPC cells via inhibiting miR-1207 and activating the PI3K/AKT signal pathway.

High collagen density augments mTOR-dependent cancer stem cells in ERα+ mammary carcinomas, and increases mTOR-independent lung metastases

Metastatic estrogen receptor alpha positive (ERα+) cancers account for most breast cancer mortality. Cancer stem cells (CSCs) and dense/stiff extracellular matrices are implicated in aggression and therapy resistance. We examined this interplay and response to mTOR inhibition using ERα+ adenocarcinomas from NRL-PRL females in combination with Col1a1^tmJae/+ (mCol1a1) mice, which accumulate collagen-I around growing tumors. Orthotopic transplantation of tumor cells to mCol1a1 but not wildtype hosts resulted in striking desmoplasia. Mammary tumors in mCol1a1 recipients displayed higher CSC activity and enhanced AKT-mTOR and YAP activation, and these animals developed more and larger lung metastases. Treatment with the mTOR inhibitor, rapamycin, with or without the anti-estrogen, ICI182780, rapidly diminished mammary tumors, which rapidly reversed when treatment ceased. In contrast, lung metastases, which exhibited lower proliferation and pS6RP, indicating lower mTOR activity, were unresponsive, and mCol1a1 hosts continued to sustain greater metastatic burdens. These findings shed light on the influence of desmoplastic tumor microenvironments on the CSC niche and metastatic behavior in ERα+ breast cancer. The differential mTOR dependence of local mammary tumors and pulmonary lesions has implications for success of mTOR inhibitors in advanced ERα+ disease.

SHP2-Mediated Signal Networks in Stem Cell Homeostasis and Dysfunction

Stem cells, including embryonic stem cells (ESCs) and adult stem cells, play a central role in mammal organism development and homeostasis. They have two unique properties: the capacity for self-renewal and the ability to differentiate into many specialized cell types. Src homology region 2- (SH2-) containing protein tyrosine phosphatase 2 (SHP-2), a nonreceptor protein tyrosine phosphatase encoded by protein tyrosine phosphatase nonreceptor type 11 gene (PTPN11), regulates multicellular differentiation, proliferation, and survival through numerous conserved signal pathways. Gain-of-function (GOF) or loss-of-function (LOF) SHP2 in various cells, especially for stem cells, disrupt organism self-balance and lead to a plethora of diseases, such as cancer, maldevelopment, and excessive hyperblastosis. However, the exact mechanisms of SHP2 dysfunction in stem cells remain unclear. In this review, we intended to raise the attention and clarify the framework of SHP2-mediated signal pathways in various stem cells. Establishment of integrated signal architecture, from ESCs to adult stem cells, will help us to understand the changes of dynamic, multilayered pathways in response to SHP2 dysfunction. Overall, better understanding the functions of SHP2 in stem cells provides a new avenue to treat SHP2-associated diseases.

Inhibition of NF-κB Signaling Reduces the Stemness Characteristics of Lung Cancer Stem Cells

Cancer stem cells (CSCs) are a subpopulation of cancer cells that play a pivotal role in tumor development, invasion, metastasis, and recurrence. We and others have reported significant involvement of the NF-κB pathway in regulating CSCs of non-small cell lung cancer (NSCLC). In this study, we evaluated the effects of NF-κB inhibition on self-renewal, stemness, migration, and expression of genes involved in the epithelial to mesenchymal transition (EMT) and apoptosis resistance in lung CSCs. Different concentrations of the NF-κB inhibitor BMS-345541 (0.4, 4.0, and 10.0 µM), an inhibitor the NF-κB upstream kinase IKKβ, were used to treat both lung CSCs (CD166⁺CD44⁺, CD166⁺EpCAM⁺) and non-CSC NSCLC cells (CD166⁻CD44⁻, CD166⁻EpCAM⁻) in A549 and H2170 cell lines. We assessed the impact of BMS-345541 on the ability to form tumorspheres (self-renewal assay), expression of stemness genes (SOX2, OCT4, NANOG, SCA-1, and KLF4), migration, and expression of EMT and apoptosis-related genes. Inhibition of NF-κB by BMS-345541 effectively reduced the stemness, self-renewal, and migration capacity of lung CSCs. Moreover, expression of genes involved in the EMT (SNAI1 and TWIST) and apoptosis resistance (BCL-2, BAX, and BIRC5) was significantly reduced following the treatments, suggesting that NF-κB inhibition is sufficient to prevent the EMT and induce apoptosis in lung CSCs. Our findings suggest that NF-κB inhibition could reduce the capability of CSCs to maintain their population within the tumor mass, potentially decelerating cancer progression, relapse, and chemotherapy resistance.

Application of induced pluripotency in cancer studies

As soon as induced pluripotent stem cells (iPSCs) reprogramming of somatic cells were developed, the discovery attracted the attention of scientists, offering new perspectives for personalized medicine and providing a powerful platform for drug testing. The technology was almost immediately applied to cancer studies. As presented in this review, direct reprogramming of cancer cells with enforced expression of pluripotency factors have several basic purposes, all of which aim to explain the complex nature of cancer development and progression, therapy-resistance and relapse, and ultimately lead to the development of novel anti-cancer therapies. Here, we briefly present recent advances in reprogramming methodologies as well as commonalities between cell reprogramming and carcinogenesis and discuss recent outcomes from the implementation of induced pluripotency into cancer research.

The Role of CtBP1 in Oncogenic Processes and Its Potential as a Therapeutic Target

Transcriptional corepressor proteins have emerged as an important facet of cancer etiology. These corepressor proteins are often altered by loss- or gain-of-function mutations, leading to transcriptional imbalance. Thus, research directed at expanding our current understanding of transcriptional corepressors could impact the future development of new cancer diagnostics, prognostics, and therapies. In this review, our current understanding of the CtBP corepressors, and their role in both development and disease, is discussed in detail. Importantly, the role of CtBP1 overexpression in adult tissues in promoting the progression of multiple cancer types through their ability to modulate the transcription of developmental genes ectopically is explored. CtBP1 overexpression is known to be protumorigenic and affects the regulation of gene networks associated with "cancer hallmarks" and malignant behavior, including increased cell survival, proliferation, migration, invasion, and the epithelial-mesenchymal transition. As a transcriptional regulator of broad developmental processes capable of promoting malignant growth in adult tissues, therapeutically targeting the CtBP1 corepressor has the potential to be an effective method for the treatment of diverse tumor types. Although efforts to develop CtBP1 inhibitors are still in the early stages, the current progress and the future perspectives of therapeutically targeting this transcriptional corepressor are also discussed. Mol Cancer Ther; 16(6); 981-90. ©2017 AACR.

CARP-1 functional mimetics are novel inhibitors of drug-resistant triple negative breast cancers

Doxorubicin and Cisplatin are the frontline therapeutics for treatment of the triple negative breast cancers (TNBCs). Emergence of drug-resistance often contributes to failure of drugs and poor prognosis, and thus necessitates development of new and improved modalities to treat TNBCs. We generated and characterized chemotherapy-resistant TNBC cells following their culture in chronic presence of Doxorubicin or Cisplatin, and tested whether their viabilities were inhibited by a novel class of CARP- 1 functional mimetic (CFM) compounds. Analogs of parent compound CFM-4 were obtained through structure-activity based medicinal chemistry studies. CFM-4.16, a novel analog of CFM-4, caused superior inhibition of viability of TNBC cells when used in combination with doxorubicin. Doxorubicin and cisplatin inhibited viabilities of parental cells with GI₅₀ dose of 0.02–0.1 μM and 1.65 μM, respectively. The GI₅₀ dose of doxorubicin for doxorubicin-resistant TNBC cells was ≥ 10.0 μM. For Cisplatin-resistant cells, the GI₅₀ dose of Cisplatin was ≥ 6–15.0 μM for MDA-MB-468 sublines and ≥ 150.0 μM for MDA-MB-231 sublines. CFM-4.16 inhibited viability of chemotherapy-resistant TNBC cells, in part by inhibiting oncogenic cMet activation and expression, stimulating CARP-1 expression, caspase-8 cleavage and apoptosis. CFM-4.16 pretreatment enhanced anti-TNBC efficacies of inhibitors of cMET (Tevatinib) or cSrc (Dasatinib). CFM-4.16 suppressed growth of resistant TNBC cells in soft agar as well as in three-dimensional suspension cultures derived from enriched, stem-like cells. Finally, a nanolipid formulation of CFM-4.16 in combination with doxorubicin had superior efficacy in inhibiting TNBC xenograft growth. Our findings collectively demonstrate therapeutic potential of CFM-4.16 for parental and drug-resistant TNBCs.

PDE5 inhibition eliminates cancer stem cells via induction of PKA signaling

Cancer stem cells (CSCs) are involved in metastasis and resistance development, thus affecting anticancer therapy efficacy. The underlying pathways required for CSC maintenance and survival are not fully understood and only a limited number of treatment strategies to specifically target CSCs have been identified. To identify novel CSC targeting compounds, we here set-up an aldehyde dehydrogenase (ALDH)-based phenotypic screening system that allows for an automated and standardized identification of CSCs. By staining cancer cells for ALDH activity and applying high-content-based single-cell population analysis, the proportion of a potential CSC subpopulation with significantly higher ALDH activity (ALDH_high) can be quantified in a heterogeneous cell population. We confirmed high ALDH activity as surrogate marker for the CSC subpopulation in vitro and validated Wnt signaling as an essential factor for the maintenance of CSCs in SUM149 breast cancer cells. In a small molecule screen, we identified phosphodiesterase type 5 (PDE5) inhibition as potential strategy to target CSC maintenance and survival in multiple cancer cell lines. CSC elimination by PDE5 inhibition was not dependent on PKG signaling, and we suggest a novel mechanism in which PDE5 inhibition leads to elevated cGMP levels that stimulate cAMP/PKA signaling to eliminate CSCs.

Characterization of Cancer Stem Cells in Colon Adenocarcinoma Metastasis to the Liver

Background

Fifty percent of colorectal cancer (CRC) patients develop liver metastasis. This study identified and characterized cancer stem cells (CSCs) within colon adenocarcinoma metastasis to the liver (CAML).

Methods

3,3-Diaminobenzidine immunohistochemical (IHC) staining was performed on nine CAML samples for embryonic stem cell (ESC) markers OCT4, SOX2, NANOG, c-Myc, and KLF4. Immunofluorescence (IF) IHC staining was performed to investigate coexpression of two markers. NanoString mRNA expression analysis and colorimetric in situ hybridization (CISH) were performed on four snap-frozen CAML tissue samples for transcript expression of these ESC markers. Cells stained positively and negatively for each marker by IHC and CISH staining were counted and analyzed.

Results

3,3-Diaminobenzidine IHC staining, and NanoString and CISH mRNA analyses demonstrated the expression of OCT4, SOX2, NANOG, c-Myc, and KLF4 within in all nine CAML samples, except for SOX2 which was below detectable levels on NanoString mRNA analysis. IF IHC staining showed the presence of a SOX2⁺/NANOG⁺/KLF4⁺/c-Myc⁺/OCT⁻ CSC subpopulation within the tumor nests, and a SOX2⁺/NANOG⁺/KLF4⁺/c-Myc⁺/OCT4⁻ CSC subpopulation and a SOX2⁺/NANOG⁺/KLF4⁺/c-Myc⁺/OCT4⁺ CSC subpopulation within the peritumoral stroma.

Conclusion

The novel finding of three CSC subpopulations within CAML provides insights into the biology of CRC.

NSC30049 inhibits Chk1 pathway in 5-FU-resistant CRC bulk and stem cell populations

The 5-fluorouracil (5-FU) treatment induces DNA damage and stalling of DNA replication forks. These stalled replication forks then collapse to form one sided double-strand breaks, leading to apoptosis. However, colorectal cancer (CRC) stem cells rapidly repair the stalled/collapsed replication forks and overcome treatment effects. Recent evidence suggests a critical role of checkpoint kinase 1 (Chk1) in preventing the replicative stress. Therefore, Chk1 kinase has been a target for developing mono or combination therapeutic agents. In the present study, we have identified a novel orphan molecule NSC30049 (NSC49L) that is effective alone, and in combination potentiates 5-FU-mediated growth inhibition of CRC heterogeneous bulk and FOLFOX-resistant cell lines in culture with minimal effect on normal colonic epithelial cells. It also inhibits the sphere forming activity of CRC stem cells, and decreases the expression levels of mRNAs of CRC stem cell marker genes. Results showed that NSC49L induces 5-FU-mediated S-phase cell cycle arrest due to increased load of DNA damage and increased γ-H2AX staining as a mechanism of cytotoxicity. The pharmacokinetic analysis showed a higher bioavailability of this compound, however, with a short plasma half-life. The drug is highly tolerated by animals with no pathological aberrations. Furthermore, NSC49L showed very potent activity in a HDTX model of CRC stem cell tumors either alone or in combination with 5-FU. Thus, NSC49L as a single agent or combined with 5-FU can be developed as a therapeutic agent by targeting the Chk1 pathway in 5-FU-resistant CRC heterogeneous bulk and CRC stem cell populations.

Expression of CD133 in endometrial cancer cells and its implications

Cancer stem cells are an attractive therapeutic target for cancer. The present study examined stem cell characteristics of CD133+ cells isolated from endometrial cancer. Phenotypic characteristics, proliferation, migration, anchorage-independent growth, chemoresistance, gene expression profile and tumorigenicity of CD133+ tumor cells were assessed. Primary tumor exhibited immunoreactivity for CD133. Endometrial CD133+ tumor cells enhanced proliferation rate, colony formation, chemotaxis migration ability, and chemoresistance to cisplatin, paclitaxel, and doxorubicin than CD133- cells. CD133+ cells expressed more cancer stem cells markers such as EpCAM, aldehyde dehydrogenase 1 and insulin-like growth factor-1 receptor than CD133- cells. Moreover, CD133+ cells also increased expression of embryonic stem cell markers including oct4, nanog, sox2, and cmyc than CD133- cells. Finally, CD133+ tumor cells could generate xenograft but not CD133- tumor cells. CD133 and Ki67 were extensively expressed in the xenograft. In conclusion, endometrial CD133+ tumor cells displayed cancer stem cell characteristics and might represent a valuable tool for identifying endometrial cancer stem cells and hence a potential therapeutic target.

Proinflammatory Cytokines IL-6 and TNF-α Increased Telomerase Activity through NF-κB/STAT1/STAT3 Activation, and Withaferin A Inhibited the Signaling in Colorectal Cancer Cells

There are increasing evidences of proinflammatory cytokine involvement in cancer development. Here, we found that two cytokines, IL-6 and TNF-α, activated colorectal cancer cells to be more invasive and stem-like. Combined treatment of IL-6 and TNF-α phosphorylated transcription factors STAT3 in a synergistic manner. STAT3, STAT1, and NF-κB physically interacted upon the cytokine stimulation. STAT3 was bound to the promoter region of human telomerase reverse transcriptase (hTERT). IL-6 and TNF-α stimulation further enhanced STAT3 binding affinity. Stem cell marker Oct-4 was upregulated in colorectal cancer cells upon IL-6 and TNF-α stimulation. Withaferin A, an anti-inflammatory steroidal lactone, inhibited the IL-6- and TNF-α-induced cancer cell invasion and decreased colonosphere formation. Notably, withaferin A inhibited STAT3 phosphorylation and abolished the STAT3, STAT1, and NF-κB interactions. Oct-4 expression was also downregulated by withaferin A inhibition. The binding of STAT3 to the hTERT promoter region and telomerase activity showed reduction with withaferin A treatments. Proinflammatory cytokine-induced cancer cell invasiveness is mediated by a STAT3-regulated mechanism in colorectal cancer cells. Our data suggest that withaferin A could be a promising anticancer agent that effectively inhibits the progression of colorectal cancer.

Enhanced cancer stem cell properties of a mitotically quiescent subpopulation of p75NTR-positive cells in esophageal squamous cell carcinoma

Mitotically quiescent cancer stem cells (CSCs) possess higher malignant potential than other CSCs, indicating their higher contribution to therapeutic resistance than that of other CSCs. In esophageal squamous cell carcinoma (ESCC), p75 neurotrophin receptor (p75NTR) is expressed in a candidate CSC population showing high tumorigenicity and chemoresistance. In the present study, we isolated and characterized quiescent CSCs population in ESCC based on p75NTR expression and cell cycle status. Expression of p75NTR and Ki-67 in ESCC cell lines (KYSE cells) and surgically resected ESCC specimens was detected by performing immunocytochemical analysis. p75NTR-positive KYSE cells were fractionated into quiescent and proliferating cells by performing flow cytometry with a fluorescent DNA-staining dye to determine their CSC phenotype. Immunocytochemical analysis showed that 21.8 and 36.5% of the p75NTR-positive cells were Ki-67-negative (G0), which accounted for 11.4 and 15.7% of cells in KYSE-30 and KYSE-140 cell lines, respectively. Flow cytometric cell sorting showed that p75NTR-positive cells in the G0-G1 phase (p75NTR-positive/G0-1 cells) but not in the S-G2-M phase (p75NTR-positive/S-G2-M cells) showed strong expression of stem cell-related genes Nanog, BMI-1, and p63; high colony formation ability; high tumorigenicity in a mouse xenograft model; and strong chemoresistance against cisplatin because of the expression of drug resistance genes ABCG2 and ERCC1. Label-retention assay showed that 3.4% p75NTR-positive cells retained fluorescent cell-tracing dye, but p75NTR-negative cells did not. Immunohistochemical analysis of ESCC specimens showed p75NTR expression in 39 of 95 (41.1%) patients, with a median of 13.2% (range, 3.0-80.1%) p75NTR-positive/Ki-67-negative cells, which were found to be associated with poorly differentiated histology. Our results suggest that p75NTR-positive/G0-1 cells represent quiescent CSCs in ESCC and indicate that these cells can be used as targets to investigate molecular processes regulating CSC phenotype and to develop novel therapeutic strategies.

Promyelocytic Leukemia Protein Is an Essential Regulator of Stem Cell Pluripotency and Somatic Cell Reprogramming

Promyelocytic leukemia protein (PML), the main constituent of PML nuclear bodies, regulates various physiological processes in different cell types. However, little is known about its functions in embryonic stem cells (ESC). Here, we report that PML contributes to ESC self-renewal maintenance by controlling cell-cycle progression and sustaining the expression of crucial pluripotency factors. Transcriptomic analysis and gain- or loss-of-function approaches showed that PML-deficient ESC exhibit morphological, metabolic, and growth properties distinct to naive and closer to the primed pluripotent state. During differentiation of embryoid bodies, PML influences cell-fate decisions between mesoderm and endoderm by controlling the expression of Tbx3. PML loss compromises the reprogramming ability of embryonic fibroblasts to induced pluripotent stem cells by inhibiting the transforming growth factor β pathway at the very early stages. Collectively, these results designate PML as a member of the regulatory network for ESC naive pluripotency and somatic cell reprogramming.

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PML is essential for the maintenance of naive pluripotent cells

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PML prevents the naive to primed pluripotency transition

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PML influences cell-fate commitment through Tbx3 regulation

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PML is required for iPSCs formation via regulation of TGF signaling pathway

The Identification of Three Cancer Stem Cell Subpopulations within Moderately Differentiated Lip Squamous Cell Carcinoma

Aim

To identify and characterize cancer stem cells (CSCs) in moderately differentiated lip squamous cell carcinoma (MDLSCC).

Method

MDLSCC samples underwent 3,3-diaminobenzidine (DAB) immunohistochemical (IHC) staining for squamous cell carcinoma marker EMA, CSC marker CD44 and embryonic stem cell markers NANOG, octamer-binding transcription factor 4 (OCT4), spalt-like transcription factor 4 (SALL4), sex-determining region Y-box 2 (SOX2), and phosphorylated signal transducer and activator of transcription 3 (pSTAT3). Immunofluorescent IHC staining was performed on two MDLSCC samples. Western blotting (WB) was used to confirm the expression of the aforementioned proteins and their transcription activation was investigated using NanoString and RT-qPCR.

Results

IHC staining demonstrated the presence of (1) an EMA⁺/CD44⁺/SALL4⁺/NANOG⁺/pSTAT3⁺/SOX2⁺/OCT4⁻ CSC subpopulation within the tumor nests (TNs); (2) a CD44⁺/SALL4⁺/NANOG⁺/pSTAT3⁺/SOX2⁺/OCT4⁻ CSC subpopulation; and (3) a CD44⁺/SALL4⁺/NANOG⁺/pSTAT3⁺/SOX2⁺/OCT4⁺ CSC subpopulation within the stroma, between the TNs. NanoString and RT-qPCR confirmed the presence of mRNA for CD44, SALL4, STAT3, SOX2, and OCT4, and WB confirmed the presence of NANOG, pSTAT3, SOX2, and OCT4.

Conclusion

This study demonstrates three putative CSC subpopulations within MDLSCC.

Induction of metastasis, cancer stem cell phenotype, and oncogenic metabolism in cancer cells by ionizing radiation

Radiation therapy is one of the major tools of cancer treatment, and is widely used for a variety of malignant tumours. Radiotherapy causes DNA damage directly by ionization or indirectly via the generation of reactive oxygen species (ROS), thereby destroying cancer cells. However, ionizing radiation (IR) paradoxically promotes metastasis and invasion of cancer cells by inducing the epithelial-mesenchymal transition (EMT). Metastasis is a major obstacle to successful cancer therapy, and is closely linked to the rates of morbidity and mortality of many cancers. ROS have been shown to play important roles in mediating the biological effects of IR. ROS have been implicated in IR-induced EMT, via activation of several EMT transcription factors—including Snail, HIF-1, ZEB1, and STAT3—that are activated by signalling pathways, including those of TGF-β, Wnt, Hedgehog, Notch, G-CSF, EGFR/PI3K/Akt, and MAPK. Cancer cells that undergo EMT have been shown to acquire stemness and undergo metabolic changes, although these points are debated. IR is known to induce cancer stem cell (CSC) properties, including dedifferentiation and self-renewal, and to promote oncogenic metabolism by activating these EMT-inducing pathways. Much accumulated evidence has shown that metabolic alterations in cancer cells are closely associated with the EMT and CSC phenotypes; specifically, the IR-induced oncogenic metabolism seems to be required for acquisition of the EMT and CSC phenotypes. IR can also elicit various changes in the tumour microenvironment (TME) that may affect invasion and metastasis. EMT, CSC, and oncogenic metabolism are involved in radioresistance; targeting them may improve the efficacy of radiotherapy, preventing tumour recurrence and metastasis. This study focuses on the molecular mechanisms of IR-induced EMT, CSCs, oncogenic metabolism, and alterations in the TME. We discuss how IR-induced EMT/CSC/oncogenic metabolism may promote resistance to radiotherapy; we also review efforts to develop therapeutic approaches to eliminate these IR-induced adverse effects.

Epigenetic control of cancer by neuropeptides

Neuropeptides act as neurohormones, neurotransmitters and/or neuromodulators. Neuropeptides maintain physiological homeostasis and are paramount in molecular mechanisms of disease progression and regulation, including in cancer. Neuropeptides, by their definition, originate and are secreted from the neuronal cells, they are able to signal to neighboring cells or are released into the blood flow, if they act as neurohormones. The majority of neuropeptides exert their functions through G protein-coupled receptors, with certain exceptions. Although previous studies indicate that neuropeptides function in supporting proliferation of malignant cells in many types of solid tumor, the antitumorigenic action of the neuropeptides and their receptors, for example, in gastric cancers and chondrosarcoma, were also reported. It is known that epigenetically modified chromatin regulates molecular mechanisms involved in gene expression and malignant progression. The epigenetic modifications are genetically heritable, although they do not cause changes in DNA sequence. DNA methylation, histone modifications and miRNA expression are subject to those modifications. While there is substantial data on epigenetic regulation of neuropeptides, the epigenetic control of cancer by neuropeptides is considered to be uncharted territory. The aim of the current review is to describe the involvement of neuropeptides in the epigenetic machinery of cancer based on data obtained from our laboratory and from other authors.

Characterization of Cancer Stem Cells in Moderately Differentiated Buccal Mucosal Squamous Cell Carcinoma

Aim

To identify and characterize cancer stem cells (CSC) in moderately differentiated buccal mucosa squamous cell carcinoma (MDBMSCC).

Methods

Four micrometer-thick, formalin-fixed, paraffin-embedded MDBMSCC samples from six patients underwent 3,3-diaminobenzidine (DAB) immunohistochemical (IHC) staining for the embryonic stem cell (ESC) markers, NANOG, OCT4, SALL4, SOX2, and pSTAT3; cancer stem cell marker, CD44; squamous cell carcinoma (SCC) marker, EMA; and endothelial marker, CD34. The transcriptional activities of the genes encoding NANOG, OCT4, SOX2, SALL4, STAT3, and CD44 were studied using NanoString gene expression analysis and colorimetric in situ hybridization (CISH) for NANOG, OCT4, SOX2, SALL4, and STAT3.

Results

Diaminobenzidine and immunofluorescent (IF) IHC staining demonstrated the presence of (1) an EMA⁺/CD44⁺/SOX2⁺/SALL4⁺/OCT4⁺/pSTAT3⁺/NANOG⁺ CSC subpopulation within the tumor nests; (2) an EMA⁻/CD44⁻/CD34⁻/SOX2⁺/OCT4⁺/pSTAT3⁺/NANOG⁺ subpopulation within the stroma between the tumor nests; and (3) an EMA⁻/CD44⁻/CD34⁺/SOX2⁺/SALL4⁺/OCT4⁺/pSTAT3⁺/NANOG⁺ subpopulation on the endothelium of the microvessels within the stroma. The expression of CD44, SOX2, SALL4, OCT4, pSTAT3, and NANOG was confirmed by the presence of mRNA transcripts, using NanoString analysis and NANOG, OCT4, SOX2, SALL4, and STAT3 by CISH staining.

Conclusion

This study demonstrated a novel finding of three separate CSC subpopulations within MDBMSCC: (1) within the tumor nests expressing EMA, CD44, SOX2, SALL4, OCT4, pSTAT3, and NANOG; (2) within the stroma expressing SOX2, SALL4, OCT4, pSTAT3, and NANOG; and (3) on the endothelium of the microvessels within the stroma expressing CD34, SOX2, SALL4, OCT4, pSTAT3, and NANOG.

Cancer Stem Cell Quiescence and Plasticity as Major Challenges in Cancer Therapy

Cells with stem-like properties, tumorigenic potential, and treatment-resistant phenotypes have been identified in many human malignancies. Based on the properties they share with nonneoplastic stem cells or their ability to initiate and propagate tumors in vivo, such cells were designated as cancer stem (stem-like) or tumor initiating/propagating cells. Owing to their implication in treatment resistance, cancer stem cells (CSCs) have been the subject of intense investigation in past years. Comprehension of CSCs' intrinsic properties and mechanisms they develop to survive and even enhance their aggressive phenotype within the hostile conditions of the tumor microenvironment has reoriented therapeutic strategies to fight cancer. This report provides selected examples of malignancies in which the presence of CSCs has been evidenced and briefly discusses methods to identify, isolate, and functionally characterize the CSC subpopulation of cancer cells. Relevant biological targets in CSCs, their link to treatment resistance, proposed targeting strategies, and limitations of these approaches are presented. Two major aspects of CSC physiopathology, namely, relative in vivo quiescence and plasticity in response to microenvironmental cues or treatment, are highlighted. Implications of these findings in the context of the development of new therapies are discussed.

Developmental signaling pathways regulating mammary stem cells and contributing to the etiology of triple-negative breast cancer

Cancer has been considered as temporal and spatial aberrations of normal development in tissues. Similarities between mammary embryonic development and cell transformation suggest that the underlying processes required for mammary gland development are also those perturbed during various stages of mammary tumorigenesis and breast cancer (BC) development. The master regulators of embryonic development Cripto-1, Notch/CSL, and Wnt/β-catenin play key roles in modulating mammary gland morphogenesis and cell fate specification in the embryo through fetal mammary stem cells (fMaSC) and in the adult organism particularly within the adult mammary stem cells (aMaSC), which determine mammary progenitor cell lineages that generate the basal/myoepithelial and luminal compartments of the adult mammary gland. Together with recognized transcription factors and embryonic stem cell markers, these embryonic regulatory molecules can be inappropriately augmented during tumorigenesis to support the tumor-initiating cell (TIC)/cancer stem cell (CSC) compartment, and the effects of their deregulation may contribute for the etiology of BC, in particular the most aggressive subtype of BC, triple-negative breast cancer (TNBC). This in depth review will present evidence of the involvement of Cripto-1, Notch/CSL, and Wnt/β-catenin in the normal mammary gland morphogenesis and tumorigenesis, from fMaSC/aMaSC regulation to TIC generation and maintenance in TNBC. Specific therapies for treating TNBC by targeting these embryonic pathways in TICs will be further discussed, providing new opportunities to destroy not only the bulk tumor, but also TICs that initiate and promote the metastatic spread and recurrence of this aggressive subtype of BC.

Pluripotency transcription factors in lung cancer-a review

Lung cancer is the leading cause of cancer-related mortality worldwide. Diagnosis of lung cancer in an early stage is still a challenge due to the asymptomatic course of early stages of the disease and the lack of a standard screening program for the population. Nowadays, learning about the mechanisms that lead to cancerogenesis in the lung is crucial for the development of new diagnostic and therapeutic strategies. Recently, many studies have proved that cancer stem cells (CSCs) are responsible for the initiation, progression, metastasis, recurrence, and even resistance of chemo- and radiotherapeutic treatment in patients with lung cancer. The expression of pluripotency transcription factors is responsible for stemness properties. In this review, we summarize the current knowledge on the role of CSCs and pluripotency transcription factors in lung carcinogenesis.