Stem cells, colorectal cancer and cancer stem cell markers correlations

Development of a 5-mRNAsi-related gene signature to predict the prognosis of colon adenocarcinoma

Aim

To create a prognosis model based on mRNA-based stem index (mRNAsi) for evaluating the prognostic outcomes of colon adenocarcinoma (COAD).

Background

Generation of heterogeneous COAD cells could be promoted by the self-renewal and differentiation potential of cancer stem cells (CSCs). Biomarkers contributing to the development of COAD stem cells remained to be discovered.

Objective

To develop and validate an mRNAsi-based risk model for estimating the prognostic outcomes of patients suffering from COAD.

Methods

Samples were collected from Rectal Adenocarcinoma (TCGA-READ) PanCancer Atlas datasets, The Cancer Genome Atlas Colon Adenocarcinoma (TCGA-COAD), and the GSE87211 dataset. MRNAsi was calculated by one-class logistic regression (OCLR) algorithm. Under the criterion of correlation greater than 0.4, genes related to mRNAsi were screened and clustered. Meanwhile, differentially expressed genes (DEGs) between molecular subtypes were identified to establish a risk model. According to the median risk score value for immunotherapy and results from immune cell infiltration and clinicopathological analyses, clusters and patients were divided into high-RiskScore and low-RiskScore groups. Cell apoptosis and viability were detected by flow cytometer and Cell Counting Kit-8 (CCK-8) assay, respectively.

Results

A negative correlation between mRNAsi and clinical stages was observed. Three clusters of patients (C1, C2, and C3) were defined based on a total of 165 survival-related mRNAsi genes. Specifically, C1 patients had greater immune cell infiltration and a poorer prognosis. A 5-mRNAsi-gene signature (HEYL, FSTL3, FABP4, ADAM8, and EBF4) served as a prediction index for COAD prognosis. High-RiskScore patients had a poorer prognosis and higher level of immune cell infiltration. In addition, the five genes in the signature all showed a high expression in COAD cells. Knocking down HEYL promoted COAD cell apoptosis and inhibited viability.

Conclusion

Our mRNAsi risk model could better predict the prognosis of COAD patients.

Preventive cancer stem cell-based vaccination modulates tumor development in syngeneic colon adenocarcinoma murine model

BACKGROUND

Cancer stem cells (CSCs), a rare sub-fraction of tumor cells, with the capability of self-renewal and strong oncogenicity are tightly responsible for chemo and radio resistance and tumor metastasis in colorectal cancer. Hence, CSCs targeting would improve the efficacy of therapeutic strategies and clinical outcomes.

METHODS

Here, using three-dimensional CSC spheroids and syngeneic mice model, we evaluated the cancer preventive impact of CSCs-based vaccination. CSCs enrichment was performed via colonosphere formation from CT-26 cell line and CT-26-derived tumor biopsy and characterized by confirming high expression of key stemness genes (OCT4, SOX2, and NANOG) and CSC-related surface biomarkers (CD166, DCLK1, and CD133) via real-time PCR and flow cytometry, respectively. Then, the stemness phenotype and self-renewal in CSC-enriched spheroids were further confirmed by showing serial sphere formation capacity, clonogenicity potential, and enhanced in vivo tumorigenic capacity compared to their parental counterparts. CSCs lysates were used as vaccines in prophylactic settings compared to the parental cell lysate and PBS groups.

RESULT

Immunization of syngeneic mice with CSCs lysates was effective in the prevention of tumor establishment and significantly decreased tumor growth rate accompanied by an improvement in survival rate in tumor-bearing mice compared to groups subjected to parental cells lysate and PBS. These results, for the first time, showed that mice immunized with cell lysate from tumor biopsy-derived spheroids are resistant to tumor induction. Immunofluorescence staining indicated that only the serum antibodies from CSC-vaccinated mice reacted with colonospheres.

CONCLUSIONS

These findings represent CSCs lysate-based vaccination as a potential approach to hampering immunotherapy failure of colorectal cancer which along with other traditional therapies may effectively apply to prevent the establishment of aggressive tumors harboring stemness features.

Dissecting the Mechanism of Action of Spiperone-A Candidate for Drug Repurposing for Colorectal Cancer

Simple Summary

Despite advances in primary and adjuvant treatments, approximately 50% of colorectal cancer (CRC) patients still die from recurrence and metastatic disease. Thus, alternative and more effective therapeutic approaches are expected to be developed. Drug repurposing is increasing interest in cancer therapy, as it represents a cheaper and faster alternative strategy to de novo drug synthesis. Psychiatric medications are promising as a new generation of antitumor drugs. Here, we demonstrate that spiperone—a licensed drug for the treatment of schizophrenia—induces apoptosis in CRC cells. Our data reveal that spiperone’s cytotoxicity in CRC cells is mediated by phospholipase C activation, intracellular calcium homeostasis dysregulation, and irreversible endoplasmic reticulum stress induction, resulting in lipid metabolism alteration and Golgi apparatus damage. By identifying new targetable pathways in CRC cells, our findings represent a promising starting point for the design of novel therapeutic strategies for CRC.

Abstract

Approximately 50% of colorectal cancer (CRC) patients still die from recurrence and metastatic disease, highlighting the need for novel therapeutic strategies. Drug repurposing is attracting increasing attention because, compared to traditional de novo drug discovery processes, it may reduce drug development periods and costs. Epidemiological and preclinical evidence support the antitumor activity of antipsychotic drugs. Herein, we dissect the mechanism of action of the typical antipsychotic spiperone in CRC. Spiperone can reduce the clonogenic potential of stem-like CRC cells (CRC-SCs) and induce cell cycle arrest and apoptosis, in both differentiated and CRC-SCs, at clinically relevant concentrations whose toxicity is negligible for non-neoplastic cells. Analysis of intracellular Ca²⁺ kinetics upon spiperone treatment revealed a massive phospholipase C (PLC)-dependent endoplasmic reticulum (ER) Ca²⁺ release, resulting in ER Ca²⁺ homeostasis disruption. RNA sequencing revealed unfolded protein response (UPR) activation, ER stress, and induction of apoptosis, along with IRE1-dependent decay of mRNA (RIDD) activation. Lipidomic analysis showed a significant alteration of lipid profile and, in particular, of sphingolipids. Damage to the Golgi apparatus was also observed. Our data suggest that spiperone can represent an effective drug in the treatment of CRC, and that ER stress induction, along with lipid metabolism alteration, represents effective druggable pathways in CRC.

Significant co-expression of putative cancer stem cell markers, EpCAM and CD166, correlates with tumor stage and invasive behavior in colorectal cancer

BACKGROUND

The crucial oncogenic role of cancer stem cells (CSCs) in tumor maintenance, progression, drug resistance, and relapse has been clarified in different cancers, particularly in colorectal cancer (CRC). The current study was conducted to evaluate the co-expression pattern and clinical significance of epithelial cell adhesion molecules (EpCAM) and activated leukocyte cell adhesion (CD166 or ALCAM) in CRC patients.

METHODS

This study was carried out on 458 paraffin-embedded CRC specimens by immunohistochemistry on tissue microarray (TMA) slides.

RESULTS

Elevated expression of EpCAM and CD166 was observed in 61.5% (246/427) and 40.5% (164/405) of CRC cases. Our analysis showed a significant positive association of EpCAM expression with tumor size (P = 0.02), tumor stage (P = 0.007), tumor differentiate (P = 0.005), vascular (P = 0.01), neural (P = 0.01), and lymph node (P = 0.001) invasion. There were no significant differences between CD166 expression and clinicopathological parameters. Moreover, the combined analysis demonstrated a reciprocal significant correlation between EpCAM and CD166 expression (P = 0.02). Interestingly, there was a significant positive correlation between EpCAM/CD166 phenotypes expression and tumor stage (P = 0.03), tumor differentiation (P = 0.05), neural, and lymph node invasion (P =0.01).

CONCLUSIONS

The significant correlation of EpCAM and CD166 expression and their association with tumor progression and aggressive behavior is the reason for the suggestion of these two CSC markers as promising targets to promote novel effective targeted-therapy strategies for cancer treatment in the present study.

Stem cells as therapeutic targets in colorectal cancer

Colorectal cancer continues to represent a significant burden on public health as the second highest cause of cancer mortality, when men and women are combined, in the US. About 50% of patients either present with late-stage metastatic disease, or develop metastatic recurrences, and ultimately die. In turn, this mortality largely reflects cancer stem cells, tumor-initiating cells that are responsible for cancer progression, drug resistance, recurrence and metastasis. This review summarizes the unique properties of colorectal cancer stem cells, and the emerging strategies by which they can be selectively targeted as a therapeutic approach to eradicating this disease.

Clinicopathological Significance of Tumor Stem Cell Markers ALDH1 and CD133 in Colorectal Carcinoma

Background & Objective:

Colorectal cancer (CRC) is the third most common cancer worldwide with a high mortality rate. The main causes of death in patients are recurrence and metastasis which are mainly attributed to the small subpopulation of cells within tumors called cancer stem cells (CSCs). This study aimed to evaluate the correlation between the expression of ALDH1 and CD133 as CSC associated markers and clinicopathological characteristics in CRC.

Methods:

In this cross-sectional study, a total of 483 CRC tumor samples were immunohistochemically stained for detection of CD133 and ALDH1 markers. Correlations of marker expression with clinicopathological factors were also evaluated.

Results:

There was a significant correlation between the luminal intensity of CD133 and neural invasion (P=0.05) and between the cytoplasmic intensity of CD133 and metastasis (P=0.05). In terms of H-score, a positive significant relation was observed between cytoplasmic expression of CD133 and lymph node (P=0.02), neural (P=0.04) and vascular invasion (P=0.02). The ALDH1 cytoplasmic expression showed a significant correlation with tumor size (P=0.001).

Conclusion:

Our findings showed that increased expression of CD133 and ALDH1 is associated with tumor progression and worse outcomes in CRC patients. These markers can be good candidates for localized targeting of CSCs using antibodies. Future researches need to be improved approaches for early detection of CRC, and treatment monitoring for CRC and other cancers.

Diacerein treatment prevents colitis-associated cancer in mice

BACKGROUND

Inflammation is a well-established enabling factor for cancer development and provides a framework for the high prevalence of colon cancer in inflammatory bowel disease. In accordance, chronic inflammation has recently been implicated in the development of cancer stem cells (CSCs). However, the mechanism whereby anti-inflammatory drugs act in the prevention of colitis-associated cancer (CAC) is only partially understood.

AIM

To evaluate the role of diacerein (DAR), an anti-inflammatory drug that mainly acts through the inhibition of interleukin (IL)-1β expression in the development of CSCs and CAC.

METHODS

The effects of DAR on colon inflammation in mice with CAC were evaluated by inflammatory index, reverse real-time transcription polymerase chain reaction and western blot. Cytokine levels were measured by enzyme-linked immunosorbent assay. Cells assays evaluated the effects of DAR on CSCs. Immunohistochemistry and apoptosis assays were also used to evaluate the effects of DAR on tumorigenesis associated with inflammation.

RESULTS

DAR treatment reduced colon inflammation as well as the number and size of tumors in azoxymethane plus dextran sulphate sodium-treated animals. Accordingly, DAR treatment was associated with reduced intracellular signals of inflammation (inhibitor of nuclear factor kappa B kinase and c-Jun N-terminal kinase phosphorylation) in the colon. In addition, DAR treatment was associated with a decrease in colon CSC formation, suggesting that besides reducing colonic inflammation, DAR has a direct effect on the inhibition of colon carcinogenesis.

CONCLUSION

Together, these data indicate that DAR-mediated IL-1β suppression attenuates inflammation-induced colon cancer and CSC formation, highlighting DAR as a potential candidate for the chemoprevention of CAC.

Cancer Stem Cells: Acquisition, Characteristics, Therapeutic Implications, Targeting Strategies and Future Prospects

Since last two decades, the major cancer research has focused on understanding the characteristic properties and mechanism of formation of Cancer stem cells (CSCs), due to their ability to initiate tumor growth, self-renewal property and multi-drug resistance. The discovery of the mechanism of acquisition of stem-like properties by carcinoma cells via epithelial-mesenchymal transition (EMT) has paved a way towards a deeper understanding of CSCs and presented a possible avenue for the development of therapeutic strategies. In spite of years of research, various challenges, such as identification of CSC subpopulation, lack of appropriate experimental models, targeting cancer cells and CSCs specifically without harming normal cells, are being faced while dealing with CSCs. Here, we discuss the biology and characteristics of CSCs, mode of acquisition of stemness (via EMT) and development of multi-drug resistance, the role of tumor niche, the process of dissemination and metastasis, therapeutic implications of CSCs and necessity of targeting them. We emphasise various strategies being developed to specifically target CSCs, including those targeting biomarkers, key pathways and microenvironment. Finally, we focus on the challenges that need to be subdued and propose the aspects that need to be addressed in future studies in order to broaden the understanding of CSCs and develop novel strategies to eradicate them in clinical applications. Graphical Abstract Cancer Stem Cells(CSCs) have gained much attention in the last few decades due to their ability to initiate tumor growth and, self-renewal property and multi-drug resistance. Here, we represent the CSC model of cancer, Characteristics of CSCs, acquisition of stemness and metastatic dissemination of cancer, Therapeutic implications of CSCs and Various strategies being employed to target and eradicate CSCs.

A Nucleotide Analog Prevents Colitis-Associated Cancer via Beta-Catenin Independently of Inflammation and Autophagy

BACKGROUND & AIMS

Chronic bowel inflammation increases the risk of colon cancer; colitis-associated cancer (CAC). Thiopurine treatments are associated with a reduction in dysplasia and CAC in inflammatory bowel disease (IBD). Abnormal Wnt/β-catenin signalling is characteristic of >90% of colorectal cancers. Immunosuppression by thiopurines is via Rac1 GTPase, which also affects Wnt/β-catenin signalling. Autophagy is implicated in colonic tumors, and topical delivery of the thiopurine thioguanine (TG) is known to alleviate colitis and augment autophagy. This study investigated the effects of TG in a murine model of CAC and potential mechanisms.

METHODS

Colonic dysplasia was induced by exposure to azoxymethane (AOM) and dextran sodium sulfate (DSS) in wild-type (WT) mice and mice harboring intestinal epithelial cell-specific deletion of autophagy related 7 gene (Atg7^ΔIEC). TG or vehicle was administered intrarectally, and the effect on tumor burden and β-catenin activity was assessed. The mechanisms of action of TG were investigated in vitro and in vivo.

RESULTS

TG ameliorated DSS colitis in wild-type but not Atg7^ΔIEC mice, demonstrating that anti-inflammatory effects of locally delivered TG are autophagy-dependent. However, TG inhibited CAC in both wild-type and Atg7^ΔIEC mice. This was associated with decreased β-catenin activation/nuclear translocation demonstrating that TG's inhibition of tumorigenesis occurred independently of anti-inflammatory and pro-autophagic actions. These results were confirmed in cell lines, and the dependency on Rac1 GTPase was demonstrated by siRNA knockdown and overexpression of constitutively active Rac1.

CONCLUSIONS

Our findings provide evidence for a new mechanism that could be exploited to improve CAC chemoprophylactic approaches.

The Association Between Inflammation, Epithelial Mesenchymal Transition and Stemness in Colorectal Carcinoma

Background

Inflammation plays an important albeit dual role in carcinogenesis. Survival studies have highlighted the prognostic significance of peritumorous inflammation. Currently, the theoretical background allows inflammation, epithelial mesenchymal transition (EMT) and the closely associated stem cell differentiation in colorectal carcinoma (CRC) to be linked. However, there is scarce direct morphological evidence.

Purpose and methods

The aim of our study was to investigate the role of inflammation in cancer growth and invasion by analyzing the association between inflammation and known morphological prognostic features of colorectal cancer, EMT, stemness and mismatch repair (MMR) protein expression. The study was designed as a retrospective morphological and immunohistochemical assessment of 553 consecutive cases of surgically treated primary CRC.

Results

There were statistically significant associations between high-grade inflammation and lower pT (p = 0.002), absence of lymph node metastases (p < 0.001) and less frequent lymphatic (p = 0.003), venous (p = 0.017), arterial (p = 0.012), perineural (p = 0.001) and intraneural (p = 0.01) invasion. In contrast, Crohn's like reaction (CLR) by density of lymphoid follicles in the invasive front lacked significant differences in regard to pT, pN, tumor invasion into surrounding structures (blood or lymphatic vessels, nerves), grade or necrosis (all p > 0.05). The expression of E-cadherin, CD44 and MMR proteins yielded no statistically significant associations with peritumorous inflammation by Klintrup-Mäkinen score or the density of lymphoid follicles. Nevertheless, E-cadherin levels were significantly associated with the density of eosinophils (p = 0.007).

Conclusion

High-grade peritumorous inflammation is associated with beneficial morphologic CRC features, including less frequent manifestations of invasion, and is not secondary to tissue damage and necrosis. CLR is not associated with cancer spread by pTN; this finding indirectly suggests an independent role of CLR in carcinogenesis. Further, inflammation by Klintrup-Mäkinen grade and CLR is not dependent on epithelial-mesenchymal transition and stem cell differentiation. Our study highlights the complex associations between inflammation, tumor morphology, EMT, stemness and MMR protein expression in human CRC tissues.

20(R)-Ginsenoside Rg3 Influences Cancer Stem Cell Properties and the Epithelial-Mesenchymal Transition in Colorectal Cancer via the SNAIL Signaling Axis

Background

Cancer stem cells (CSCs) have been proposed as central drivers of cancer relapse in many cancers. In the present study, we investigated the inhibitory effect of 20(R)-Ginsenoside Rg3 (Rg3R), a major active component of ginseng saponin, on CSC-like cells and the Epithelial-Mesenchymal Transition (EMT) in colorectal cancer (CRC).

Methods

The effects of ginsenoside Rg3R on the colony-forming, migration, invasion, and wound-healing abilities of CRC cells were determined in HT29 and SW620 cell lines in vitro. Further, ginsenoside Rg3R was given intraperitoneally at 5mg/kg of mouse body weight to check its effect on the metastasis of CRC cells in vivo.

Results

Ginsenoside Rg3R significantly inhibited CSC properties, but did not affect cell proliferation. Moreover, ginsenoside Rg3R treatment significantly inhibited the motility of CRC cells based on migration, invasion, and wound-healing assays. The inhibitory effects of ginsenoside Rg3R on CRC are potentially mediated by significant down-regulation of the expression of stemness genes and EMT markers in CRC cells in a SNAIL-dependent manner. Furthermore, ginsenoside Rg3R treatment decreased both the number and size of tumor nodules in the liver, lung, and kidney tissues in a metastasis mouse model.

Conclusion

These findings highlighted the potential use of ginsenoside Rg3R in clinical applications for colorectal cancer treatment.

Exosomes, metastases, and the miracle of cancer stem cell markers

Cancer-initiating cells (CIC) are the driving force in tumor progression. There is strong evidence that CIC fulfill this task via exosomes (TEX), which modulate and reprogram stroma, nontransformed cells, and non-CIC. Characterization of CIC, besides others, builds on expression of CIC markers, many of which are known as metastasis-associated molecules. We here discuss that the linkage between CIC/CIC-TEX and metastasis-associated molecules is not fortuitously, but relies on the contribution of these markers to TEX biogenesis including loading and TEX target interactions. In addition, CIC markers contribute to TEX binding- and uptake-promoted activation of signaling cascades, transcription initiation, and translational control. Our point of view will be outlined for pancreas and colon CIC highly expressing CD44v6, Tspan8, EPCAM, claudin7, and LGR5, which distinctly but coordinately contribute to tumor progression. Despite overwhelming progress in unraveling the metastatic cascade and the multiple tasks taken over by CIC-TEX, there remains a considerable gap in linking CIC biomarkers, TEX, and TEX-initiated target modulation with metastasis. We will try to outline possible bridges, which could allow depicting pathways for new and expectedly powerful therapeutic interference with tumor progression.

[Culture and identification of tumor stem cells from surgically resected colorectal cancer tissues]

OBJECTIVE

To obtain cancer stem cells (CSCs) from surgically resected colorectal cancer specimens and identify their stem cell characteristics.

METHODS

Colorectal cancer tissue specimen obtained from a patient undergoing radical resection of colorectal cancer were implanted in nude mice, and the xenograft was harvested 1 month later to obtain purified tumor cells by enzyme digestion and adherent culture. The CSCs were screened by limiting dilution method and serum-free culture to identify their phenotypes. Soft agar colony assay was used to assess the proliferative ability of the CSCs and human colorectal cancer cell line SW480. The tumorigenic ability of the isolated CSCs and SW480 cells was evaluated by observing their subcutaneous tumor formation in nude mice. Western blotting and immunofluorescence assay were used to detect the immunophenotype of the CSCs and SW480 cells.

RESULTS

The primary cultured CSCs from clinical specimens of colorectal cancer underwent differentiation in the presence of serum in the culture. Soft agar colony formation assay showed that the CSCs had a colony formation rate above 50%, significantly higher than the rate of colorectal cancer SW480 cells (4.41%; P < 0.01). In nude mice, subcutaneous injection of 500 CSCs was sufficient to result in subcutaneous tumor formation, while the injection of 500 SW480 cells failed to form any subcutaneous tumors. The CSCs expressed CD133 and CD44 but not CK7, while SW480 cells expressed CK7 but not CD133 or CD44.

CONCLUSIONS

CSCs can be derived by primary culture of cancer cells obtained from surgically resected colorectal cancer tissue followed by serum-free culture, and the CSCs obtained have self-renewal and differentiation abilities.

Targeting Cancer Stem Cells to Overcome Chemoresistance

Cancers are heterogeneous at the cell level, and the mechanisms leading to cancer heterogeneity could be clonal evolution or cancer stem cells. Cancer stem cells are resistant to most anti-cancer treatments and could be preferential targets to reverse this resistance, either targeting stemness pathways or cancer stem cell surface markers. Gold nanoparticles have emerged as innovative tools, particularly for photo-thermal therapy since they can be excited by laser to induce hyperthermia. Gold nanoparticles can be functionalized with antibodies to specifically target cancer stem cells. Preclinical studies using photo-thermal therapy have demonstrated the feasibility of targeting chemo-resistant cancer cells to reverse clinical chemoresistance. Here, we review the data linking cancer stem cells and chemoresistance and discuss the way to target them to reverse resistance. We particularly focus on the use of functionalized gold nanoparticles in the treatment of chemo-resistant metastatic cancers.

Cancer Stem Cells or Tumor Survival Cells?

Research endeavors originally generated stem cell definitions for the purpose of describing normally sustainable developmental and tissue turnover processes in various species, including humans. The notion of investigating cells that possess a vague capacity of “stamm (phylum)” can be traced back to the late 19th century, mainly concentrating on cells that could produce the germline or the entire blood system. Lately, such undertakings have been recapitulated for oncogenesis, tumor growth, and cancer cell resistance to oncolytic therapies. However, due to the complexity and basic life-origin mechanisms comprising the genetic and epigenetic repertoire of the stemness in every developing or growing cell, presently there are ongoing debates regarding the biological essentials of the stem cell-like tumor initiation cells (ie, cancer stem cells; CSCs). This conceptual analysis focuses on the potential pitfalls of extrapolating that CSCs bear major traits of stemness. We propose a novel nomenclature of Tumor Survival Cells (TSCs) to further define tumor cells behaving like CSCs, based on the ruthless and detrimental features of Cancer Cell Survivology that appears fundamentally different from stem cell biology. Hence, precise academic separation of TSCs from all the stem cell-related labels applied to these unique tumor cells may help to improve scientific reasoning and strategies to decode the desperado-like survival behaviors of TSCs to eventually overcome cancer.

Selenoprotein K deficiency inhibits melanoma by reducing calcium flux required for tumor growth and metastasis

Interest has emerged in the therapeutic potential of inhibiting store operated calcium (Ca²⁺) entry (SOCE) for melanoma and other cancers because malignant cells exhibit a strong dependence on Ca²⁺ flux for disease progression. We investigated the effects of deleting Selenoprotein K (SELENOK) in melanoma since previous work in immune cells showed SELENOK was required for efficient Ca²⁺ flux through the endoplasmic reticulum Ca²⁺ channel protein, inositol 1,4,5-trisphosphate receptor (IP3R), which is due to the role SELENOK plays in palmitoylating and stabilizing the expression of IP3R. CRISPR/Cas9 was used to generate SELENOK-deficiency in human melanoma cells and this led to reduced Ca²⁺ flux and impaired IP3R function, which inhibited cell proliferation, invasion, and migration. Ca²⁺-dependent signaling through calcineurin was inhibited with SELENOK-deficiency, and gene array analyses together with evaluation of transcript and protein levels showed altered transcriptional programs that ultimately disrupted stemness and pro-growth properties. In vivo investigations were conducted using the Grm1-Tg transgenic mouse strain that develops spontaneous metastatic melanoma, which was crossed with SELENOK^−/− mice to generate the following littermates: Grm1-Tg/SELENOK^−/−, Grm1-Tg/SELENOK^−/+, Grm1-Tg/SELENOK^+/+. SELENOK-deficiency in Grm1-Tg/SELENOK^−/− male and female mice inhibited primary tumor growth on tails and ears and reduced metastasis to draining lymph nodes down to levels equivalent to non-tumor control mice. Cancer stem cell pools were also decreased in Grm1-Tg/SELENOK^−/− mice compared to littermates. These results suggest that melanoma requires SELENOK expression for IP3R dependent maintenance of stemness, tumor growth and metastasic potential, thus revealing a new potential therapeutic target for treating melanoma and possibly other cancers.

The co-stimulatory molecule B7-H3 promotes the epithelial-mesenchymal transition in colorectal cancer

B7-H3, first recognized as a co-stimulatory molecule, is abnormally expressed in cancer tissues and is associated with cancer metastasis and a poor prognosis. However, as an initial event of metastasis, the relationship between the Epithelial-Mesenchymal Transition (EMT ) in cancer cells and B7-H3 has still not been investigated. In this study, we first analyzed B7-H3 expression by immunohistochemistry in colorectal cancer tissues. B7-H3 was expressed in the cancer cell membrane and was associated with the T stage of colorectal cancer; it also showed a positive correlation with MMP2 and MMP9 expression in cancer tissues. Over-expression of B7-H3 in SW480 cells allowed cancer cells to invade and metastasize more than the control cells, whereas invasion and metastasis capabilities were decreased after B7-H3 was knocked down in Caco-2 cells. We further showed that B7-H3 down-regulated the expression of E-cadherin and β-catenin and up-regulated N-cadherin and Vimentin expression, implying that B7-H3 promoted the EMT in colorectal cancer cells. We also checked another character of the EMT, the stemness of cancer cells. CD133, CD44 and Oct4 were significantly elevated after the SW480 cells were transfected with B7-H3 and reduced in Caco-2 cells after B7-H3 was inhibited. In subsequent studies, we proved that B7-H3 upregulated the expression of Smad1 via PI3K-Akt. In conclusion, B7-H3 promotes the EMT in colorectal cancer cells by activating the PI3K-Akt pathway and upregulating the expression of Smad1.

Ginsenoside Rg3 targets cancer stem cells and tumor angiogenesis to inhibit colorectal cancer progression in vivo

Anti-angiogenic therapy has been successfully applied to treat colorectal cancer (CRC). Ginsenoside Rg3, derived from the Chinese herb ginseng, has anti-vascularization effects and can inhibit tumor growth and metastasis, and can sensitize cancer cells to chemotherapy. Therefore, in the present study, we investigated whether Rg3 could be appropriate for CRC treatment. Growth of CRC cells was assessed by an MTT (methyl thiazolyl tetrazolium) assay in vitro and using orthotopic xenograft models in vivo. mRNA expression was evaluated using real-time PCR. Protein levels were tested by western blotting, flow cytometry and immunohistochemistry. Migration was determined using a wound-healing assay. Stemness was further confirmed using a plate clone formation assay. We found that Rg3 repressed the growth and stemness of CRC cells both in vitro and in vivo. Rg3 also impaired the migration of CRC cells in vitro. Rg3 downregulated the expressions of angiogenesis-related genes, and repressed the vascularization of CRC xenografts. In addition, Rg3 strengthened the cytotoxicity of 5-Fluorouracil and oxaliplatin against orthotopic xenografts in vivo. Moreover, Rg3 downregulated the expressions of B7-H1 and B7-H3, high expressions of which were associated with reduced overall survival (OS) of CRC patients. Hence, Rg3 not only repressed the growth and stemness of CRC cells, but could also remodel the tumor microenvironment through repressing angiogenesis and promoting antitumor immunity. Therefore, Rg3 could be a novel therapeutic for the CRC treatment.

FOXD3 Regulates CSC Marker, DCLK1-S, and Invasive Potential: Prognostic Implications in Colon Cancer

The 5' (α)-promoter of the human doublecortin-like kinase 1 (DCLK1) gene becomes epigenetically silenced during colon carcinogenesis, resulting in loss of expression of the canonical long(L)-isoform1 (DCLK1-L) in human colon adenocarcinomas (hCRCs). Instead, hCRCs express a short(S)-isoform2 (DCLK1-S) from an alternate (β)-promoter of DCLK1. The current study, examined if the transcriptional activity of the (β)-promoter is suppressed in normal versus cancerous cells. On the basis of in silico and molecular approaches, it was discovered that FOXD3 potently inhibits the transcriptional activity of the (β)-promoter. FOXD3 becomes methylated in human colon cancer cells (hCCC), with loss of FOXD3 expression, allowing expression of the DCLK1(S) variant in hCCCs/hCRCs. Relative levels of FOXD3/DCLK1(S/L) were measured in a cohort of CRC patient specimens (n = 92), in relation to overall survival (OS). Patients expressing high DCLK1(S), with or without low FOXD3, had significantly worse OS compared with patients expressing low DCLK1(S). The relative levels of DCLK1-L did not correlate with OS. In a pilot retrospective study, colon adenomas from high-risk patients (who developed CRCs in <15 years) demonstrated significantly higher staining for DCLK1(S) + significantly lower staining for FOXD3, compared with adenomas from low-risk patients (who remained free of CRCs). Latter results strongly suggest a prognostic value of measuring DCLK1(S)/FOXD3 in adenomas. Overexpression of DCLK1(S), but not DCLK1(L), caused a significant increase in the invasive potential of hCCCs, which may explain worse outcomes for patients with high DCLK1-S-expressing tumors. On the basis of these data, FOXD3 is a potent repressor of DCLK1-S expression in normal cells; loss of FOXD3 in hCCCs/hCRCs allows upregulation of DCLK1-S, imparting a potent invasive potential to the cells. Mol Cancer Res; 15(12); 1678-91. ©2017 AACR.

Targeting Cancer Stem Cells-A Renewed Therapeutic Paradigm

Metastasis is often accompanied by radio- and chemotherapeutic resistance to anticancer treatments and is the major cause of death in cancer patients. Better understanding of how cancer cells circumvent therapeutic insults and how disseminated cancer clones generate life-threatening metastases would therefore be paramount to the development of effective therapeutic approaches for clinical management of malignant disease. Mounting reports over the past two decades have provided evidence for the existence of a minor population of highly malignant cells within liquid and solid tumors, which are capable of self-renewing and of regenerating secondary growths with the heterogeneity of the primary tumors from which they derive. These cells, called tumor-initiating cells or cancer stem cells (CSCs) exhibit increased resistance to standard radio- and chemotherapies and appear to have mechanisms that enable them to evade immune surveillance. CSCs are therefore considered to be responsible for systemic residual disease after cancer therapy, as well as for disease relapse. How CSCs develop, the nature of the interactions they establish with their microenvironment, their phenotypic and functional characteristics, as well as their molecular dependencies have all taken center stage in cancer therapy. Indeed, improved understanding of CSC biology is critical to the development of important CSC-based anti-neoplastic approaches that have the potential to radically improve cancer management. Here, we summarize some of the most pertinent elements regarding CSC development and properties, and highlight some of the clinical modalities in current development as anti-CSC therapeutics.

Metformin increases chemo-sensitivity via gene downregulation encoding DNA replication proteins in 5-Fu resistant colorectal cancer cells

Metformin is most widely prescribed for type 2 diabetes. Recently, evidences have shown that metformin has anticancer effects on pancreatic-, colorectal-, ovarian-, and other cancers. Because metformin has less adverse effects and is inexpensive, it could be a useful chemo-therapeutic agent with anticancer effects. In this study, we demonstrated metformin inhibited by cell proliferation, cell migration ability, clonogenic ability, and cancer stem cell population. Metformin also induced cell cycle arrest in parental-(SNU-C5), and 5-Fu resistant-colorectal cancer cell line (SNU-C5_5FuR). Moreover, a treatment that combines 5-Fu and metformin was found to have a synergistic effect on the cell proliferation rate, especially in SNU-C5_5FuR, which was mediated by the activation of AMPK pathway and NF-ƙB pathway, well-known metformin mechanisms. In this study, we suggested novel anticancer mechanism of metformin that inhibited DNA replication machinery, such as the MCM family in SNU-C5_5FuR. In conclusion, we provided that how metformin acts as not only a chemo-sensitizer, but also as a synergistic effector of 5-Fu in the 5-Fu resistant-cell line. We speculate that metformin used for adjuvant therapy is effective on 5-Fu resistant cancer cells.

Serum CD166: A novel biomarker for predicting nasopharyngeal carcinoma response to radiotherapy

The present study aimed to identify whether CD166 can be used as a biomarker for predicting the response of nasopharyngeal carcinoma (NPC) to radiotherapy. The serum concentration of CD166 in patients with NPC were detected by enzyme-linked immunosorbent assay. The secreted level of CD166 with radioresistant NPC was significantly higher than that with radiosensitive NPC. In vitro, the CD166 positive rate in the CNE2 cell membrane was significantly lower than that in the CNE2R cell membrane. The magnetic-activated cell sorting technology was used to obtain CNE-2R-CD166(+) and CNE-2R-CD166(−) cell lines. Then radiosensitivity, cell proliferation, and apoptosis were assessed using colony formation assay, cell counting kit 8 assay (CCK-8), and flow cytometry, respectively. The radiation sensitivity ratio was 1.28, indicating that the CNE2R-CD166(−) cells had a stronger radiation sensitivity. The result of CCK-8 assay indicated that the survival fraction of CNE2R-CD166(+) cells was significantly higher than that of CNE2R-CD166(−) cells. The apoptotic rate of CNE2R-CD166(+) cells was significantly lower than that of CNE2R-CD166(−) cells. Our data demonstrate that the secreted protein CD166 may be can used as a biomarker for predicting the response of NPC to radiotherapy.

Cancer Stem Cells: Cellular Plasticity, Niche, and its Clinical Relevance

Cancer handles an estimated 7.6 million deaths worldwide per annum. A recent theory focuses on the role Cancer Stem Cells (CSCs) in driving tumorigenesis and disease progression. This theory hypothesizes that a population of the tumor cell with similar functional and phenotypic characteristics as normal tissue stem cells are responsible for formation and advancement of many human cancers. The CSCs subpopulation can differentiate into non-CSC tumor cells and promote phenotypic and functional heterogeneity within the tumor. The presence of CSCs has been reported in a number of human cancers including blood, breast, brain, colon, lung, pancreas prostate and liver. Although the origin of CSCs remains a mystery, recent reports suggest that the phenotypic characteristics of CSCs may be plastic and are influenced by the microenvironment specific for the individual tumor. Such factors unique to each tumor preserve the dynamic balance between CSCs to non-CSCs cell fate, as well as maintain the proper equilibrium. Alternating such equilibrium via dedifferentiation can result in aggressiveness, as CSCs are considered to be more resistant to the conventional cancer treatments of chemotherapy and radiation. Understanding how the tumoral microenvironment affects the plasticity driven CSC niche will be critical for developing a more effective treatment for cancer by eliminating its aggressive and recurring nature that now is believed to be perpetuated by CSCs.

Oncolytic viruses against cancer stem cells: A promising approach for gastrointestinal cancer

Gastrointestinal cancer has been one of the five most commonly diagnosed and leading causes of cancer mortality over the past few decades. Great progress in traditional therapies has been made, which prolonged survival in patients with early cancer, yet tumor relapse and drug resistance still occurred, which is explained by the cancer stem cell (CSC) theory. Oncolytic virotherapy has attracted increasing interest in cancer because of its ability to infect and lyse CSCs. This paper reviews the basic knowledge, CSC markers and therapeutics of gastrointestinal cancer (liver, gastric, colon and pancreatic cancer), as well as research advances and possible molecular mechanisms of various oncolytic viruses against gastrointestinal CSCs. This paper also summarizes the existing obstacles to oncolytic virotherapy and proposes several alternative suggestions to overcome the therapeutic limitations.

Prevention of pancreatic cancer in a hamster model by cAMP decrease

Smoking and alcoholism are risk factors for the development of pancreatitis-associated pancreatic ductal adenocarcinoma (PDAC). We have previously shown that these cancers overexpressed stress neurotransmitters and cyclic adenosine monophosphate (cAMP) while the inhibitory neurotransmitter γ-aminobutyric acid (GABA) was suppressed. Using a hamster model, the current study has tested the hypothesis that cAMP decrease by GABA supplementation in the drinking water prevents the development of pancreatitis-associated PDAC. Our data reveal strong preventive effects of GABA supplementation on the development of PDAC and pancreatic intraductal neoplasia (PanIN). ELISA assays and immunohistochemistry revealed significant decreases in the levels of cAMP and interleukin 6 accompanied by reductions in the expression of several cancer stem cell markers and phosphorylated signaling proteins, which stimulate cell proliferation, and migration in pancreatic exocrine cells of GABA treated animals. We conclude that cAMP decrease by GABA supplementation inhibits multiple cancer stimulating pathways in cancer stem cells, differentiated cancer cells and the immune system, identifying this approach as promising novel tool for the prevention of PDAC in individuals with a history of smoking and alcoholism.

A novel method to limit breast cancer stem cells in states of quiescence, proliferation or differentiation: Use of gel stress in combination with stem cell growth factors

The majority of cancer stem cells exist in the G0, or quiescent phase of the cell cycle. However, the cells can escape quiescence following routine radiotherapy and chemotherapy, resulting in tumor recurrence. Presently, achieving the accurate regulation of cancer stem cell growth in order to study a specific state, including the quiescent (mostly G0 or G1 phase), proliferative (mostly S phase) or differential (mostly G2/M phase) states, can be challenging. This makes the determination of cell cycle state-specific characteristics and analysis of potential intervention treatments difficult, particularly for quiescent cells. Breast cancer stem cells were cultured on a soft or hard agar matrix surface in the presence or absence of stem cell growth factors. Cells could be successfully limited in either the quiescent, proliferative or differentiated states. These findings provide a foundation for further study of the cell cycle in breast cancer stem cells.

CD90 and CD24 Co-Expression Is Associated with Pancreatic Intraepithelial Neoplasias

Thy-1 (CD90) has been shown to be a potential marker for several different types of cancer. However, reports on CD90 expression in pancreatic intraepithelial neoplasia (PanIN) lesions are still limited where PanINs are the most important precursor lesion of pancreatic ductal adenocarcinoma (PDAC). Herein, we investigate candidate markers for PanIN lesions by examining the distribution and trend of CD90 and CD24 expression as well as their co-expression in various stages of PanINs. Thirty cases of PanINs, which were confirmed histopathologically and clinically, were used to evaluate protein expression of CD90 and CD24 by immunofluoresence double staining. CD90 was found to be mainly expressed in stroma around lesion ducts while not observed in acini and islets in PanINs. CD90 also showed increased expression in PanIN III compared to PanIN III. CD24 was mainly present in the cytoplasm and membrane of pancreatic ductal epithelia, especially in the apical epithelium of the duct. CD24 had higher expression in PanIN III compared with PanIN IIIIII or PanIN III. CD90 was expressed around CD24 sites, but there was little overlap between cells that expressed each of these proteins. A correlation analysis showed that these two proteins have a moderate relationship with PanIN stages respectively. These results suggest that co-expression of CD90 and CD24 may have an important role in the development and progression of PanINs, which is also conducive to early detection and treatment of PDAC.

Minimal residual disease in breast cancer: an overview of circulating and disseminated tumour cells

Within the field of cancer research, focus on the study of minimal residual disease (MRD) in the context of carcinoma has grown exponentially over the past several years. MRD encompasses circulating tumour cells (CTCs)—cancer cells on the move via the circulatory or lymphatic system, disseminated tumour cells (DTCs)—cancer cells which have escaped into a distant site (most studies have focused on bone marrow), and resistant cancer cells surviving therapy—be they local or distant, all of which may ultimately give rise to local relapse or overt metastasis. Initial studies simply recorded the presence and number of CTCs and DTCs; however recent advances are allowing assessment of the relationship between their persistence, patient prognosis and the biological properties of MRD, leading to a better understanding of the metastatic process. Technological developments for the isolation and analysis of circulating and disseminated tumour cells continue to emerge, creating new opportunities to monitor disease progression and perhaps alter disease outcome. This review outlines our knowledge to date on both measurement and categorisation of MRD in the form of CTCs and DTCs with respect to how this relates to cancer outcomes, and the hurdles and future of research into both CTCs and DTCs.

Prognostic Molecular Subtypes of Low-Grade Cancer of the Appendix

BACKGROUND

Appendiceal cancer (AC) patients treated with cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) often demonstrate an unpredictable variability in their survival outcomes. Biomarkers predictive of CRS/HIPEC efficacy could better guide treatment decisions. We hypothesized that variation in the transcriptional programming of AC tumors might distinguish molecular subtypes with differential outcomes after CRS/HIPEC.

STUDY DESIGN

Gene expression profiles of 2 AC cohorts were analyzed using Affymetrix whole-genome expression microarrays. Hierarchical clustering methods, Kaplan-Meier analysis, and Cox regression models were used to discover and validate prognostic molecular subtypes of AC. Gene set enrichment analysis was used to infer pathologic attributes of the molecular subtypes.

RESULTS

Unsupervised hierarchical clustering analysis of tumor expression profiles revealed a 139-gene cassette that distinguished 2 molecular subtypes (based on low vs high expression of the gene cassette) with statistically significant survival differences (disease-specific survival, p = 0.0075; progression-free survival, p = 0.0072). In a second AC cohort, the 139-gene cassette reproducibly partitioned tumors into subtypes with significant survival differences. Tumors showing high relative expression of the genes comprising the cassette associated with poor survival outcomes (disease-specific survival, p = 0.047; progression-free survival, p = 0.0079), and exhibited gene expression patterns enriched for oncogenic processes and pathways. The prognostic value of the molecular subtypes was specific for low-grade appendiceal tumors (disease-specific survival, p = 0.028; progression-free survival, p = 0.0016), and remained significant in the presence of conventional prognostic markers, including grade, surgical resection score, Eastern Cooperative Oncology Group status, and age.

CONCLUSIONS

The 139-gene cassette can have actionable clinical utility for identifying low-grade appendiceal tumor molecular subtypes predictive of therapeutic efficacy of CRS/HIPEC.

CD24 promotes HCC progression via triggering Notch-related EMT and modulation of tumor microenvironment

CD24 is known as a cell surface molecule in hematopoiesis and also described as a diagnostic marker for tumors. Previous studies suggested the important role of CD24 in hepatocellular carcinoma (HCC) pathogenesis. However, precise functions of CD24 in HCC are still unknown. Here, we found that CD24 is highly expressed in HCC both in mRNA and protein levels. Further, the epithelial-mesenchymal transition (EMT) and Notch1 signaling activations mediated by CD24 were elucidated as potential mechanisms of HCC promotion in Hepa1-6/Hepa1-6-CD24 cell models. Additionally, possible systemic immune reaction was explored through immune cells and Hepa1-6/Hepa1-6-CD24 cell co-culture. We demonstrated that the EMT process of HCC cell was effectively induced by CD24; also, the tumor immune microenvironment was changed by facilitating Notch-related EMT in vivo. These results reveal the underlying link between the HCC processes mediated by CD24. Moreover, as a clear tumor promoter, CD24 is considered a potential new target for HCC treatment.

Therapies targeting cancer stem cells: Current trends and future challenges

Traditional therapies against cancer, chemo- and radiotherapy, have multiple limitations that lead to treatment failure and cancer recurrence. These limitations are related to systemic and local toxicity, while treatment failure and cancer relapse are due to drug resistance and self-renewal, properties of a small population of tumor cells called cancer stem cells (CSCs). These cells are involved in cancer initiation, maintenance, metastasis and recurrence. Therefore, in order to develop efficient treatments that can induce a long-lasting clinical response preventing tumor relapse it is important to develop drugs that can specifically target and eliminate CSCs. Recent identification of surface markers and understanding of molecular feature associated with CSC phenotype helped with the design of effective treatments. In this review we discuss targeting surface biomarkers, signaling pathways that regulate CSCs self-renewal and differentiation, drug-efflux pumps involved in apoptosis resistance, microenvironmental signals that sustain CSCs growth, manipulation of miRNA expression, and induction of CSCs apoptosis and differentiation, with specific aim to hamper CSCs regeneration and cancer relapse. Some of these agents are under evaluation in preclinical and clinical studies, most of them for using in combination with traditional therapies. The combined therapy using conventional anticancer drugs with CSCs-targeting agents, may offer a promising strategy for management and eradication of different types of cancers.

Expression of cancer stem cell markers and their correlation with pathogenesis in vascular tumors

Vascular tumor, which belongs to a kind of complicated lesion in soft tissue tumor, is derived from mesenchymal tissue. Although many studies have been focused on the pathogenesis of vascular tumors in human, the specific mechanism of the vascular tumors was currently unclear. Previous studies have reported an association of cancer stem cells with the development of tumor in many solid tumors. Thus the purpose of this study was to explore whether different expression level of cancer stem cell markers including CD29, CD44, CD133, nestin and ALDH1 in vascular tumor may help to elucidate the possible pathogenesis of vascular tumor. In present study, tissues of 9 cases of hemangioma, 22 cases of hemangiosarcoma, 3 cases of Kaposi's sarcoma, and 5 cases of hemangioendothelioma were immunostained for CD29, CD44, CD133, nestin and ALDH1. Of the 39 vascular tumor cases included in the current study, CD29, CD133 and nestin were positive in most vascular tumor cases. Although CD44 and ALDH1 were observed in vascular tumor cases, the percentage of cells staining for the two markers was less than 2% in all cases of vascular tumor. Capillary hemangiomas exhibited significantly higher expression rate of CD29 and nestin compared with malignant vascular tumors and hemangioendotheliomas (P<0.05, Fisher's exact test), while CD44, CD133 and ALDH1 exhibited no statistically significant difference between these two groups. Pearson correlation analysis exhibited that CD29 expression and nestin expression in vascular tumor were no statistically significant relationship (C=0.288, P=0.063>0.05). Our findings confirmed that the five cancer stem cells markers, including CD29, CD44, CD133, nestin and ALDH1, exhibited different expression levels in vascular tumors and demonstrated that immunohistochemical analysis for cancer stem cells markers may provide useful information for studying the pathogenesis of vascular tumors.

Progress in understanding role of epithelial to mesenchymal transition in acquisition of stem cell properties by colorectal tumor cells

Epithelial-mesenchymal transition (EMT) is a dynamic process in which cells lose epithelial features and gain mesenchymal properties. This process not only contributes to the normal development of tissues and organs, inflammation and wound-related fibrosis or mucosal repair but also participates in carcinoma progression, promotes tumor cell invasion and metastasis and induces stem cell properties. EMT also contributes to occurrence of tumor recurrence, metastasis and multi-drug resistance. This review illuminates the mechanism that EMT promotes colorectal carcinoma cells to obtain stemness in terms of microRNAs, signaling pathways and microenvironment, with an aim to provide novel and safe strategies for clinical target therapy.

Stem and immune cells in colorectal primary tumour: Number and function of subsets may diagnose metastasis

An important percentage of colorectal cancer (CRC) patients will develop metastasis, mainly in the liver, even after a successful curative resection. This leads to a very high mortality rate if metastasis is not detected early on. Disseminated cancer cells develop from metastatic stem cells (MetSCs). Recent knowledge has accumulated about these cells particularly in CRC, so they may now be tracked from the removed primary tumour. This approach could be especially important in prognosis of metastasis because it is becoming clear that metastasis does not particularly rely on testable driver mutations. Among the many traits supporting an epigenetic amplification of cell survival and self-renewal mechanisms of MetSCs, the role of many immune cell populations present in tumour tissues is becoming clear. The amount of tumour-infiltrating lymphocytes (T, B and natural killer cells), dendritic cells and some regulatory populations have already shown prognostic value or to be correlated with disease-free survival time, mainly in immunohistochemistry studies of unique cell populations. Parallel analyses of these immune cell populations together with MetSCs in the primary tumour of patients, with later follow-up data of the patients, will define the usefulness of specific combinations of both immune and MetSCs cell populations. It is expected that these combinations, together to different biomarkers in the form of an immune score, may predict future tumour recurrences, metastases and/or mortality in CRC. It will also support the future design of improved immunotherapeutic approaches against metastasis.