Elimination Of Cancer Stem Cells Research Articles

Engineering Amyloid Aggregation as a New Way to Eliminate Cancer Stem Cells by the Disruption of Iron Homeostasis.

Cancer stem cells (CSCs) play crucial roles in tumor initiation. Amyloid β (Aβ), which is associated with Alzheimer's disease (AD), has been identified to induce cytotoxicity in tumor cells besides brain cells. Herein, we find that oligomeric Aβ1-42 and Aβ1-40 (OAβ1-42 and OAβ1-40) can repress the viability of breast CSCs. Intriguingly, OAβ1-42 and OAβ1-40 preferentially induce the growth arrest of breast CSCs by contrast with the bulk cancer cells. Further studies indicate that OAβ1-42 and OAβ1-40 disturb iron homeostasis, which results in iron accumulation in lysosomes. The iron in lysosomes then induces ROS production by Fenton reaction, leading to breast CSC death. In vivo experiments show that the tumorigenesis of breast CSCs pretreated with OAβ1-42 is inhibited. These results reveal that OAβ1-42 and OAβ1-40 are multifaceted players with the ability to eliminate CSCs. Our work may provide a new clue to better understand the biological functions of amyloid oligomers.

Quercetin induces proteolysis of mesenchymal marker vimentin through activation of caspase-3, and decreases cancer stem cell population in human papillary thyroid cancer cell line.

Back groundEpithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs) play an essential role in metastasis of papillary thyroid cancer (PTC), and vimentin is associated with lymph node metastasis and poor prognosis. Hence, inhibition of EMT and effective elimination of CSCs offers a novel target for developing new therapeutic agents. The objective of this study is to inspect the effect of quercetin, a major dietary bioactive flavonoid, on vimentin, CSCs and associated mechanism. MethodsThe first mechanism of quercetin mediated cytotoxicity was investigated in NPA cell line. Subsequently, the effect of quercetin was investigated on glycolysis, vimentin, CSCs, and the mechanism of vimentin degradation was also explored. ResultQuercetin effectively induces cytotoxicity by executing intrinsic apoptosis and activates caspase-3 through extracellular signal-regulated kinase (ERK) activation in NPA cell line having typical mesenchymal characters. Quercetin inhibits NPA cells migration and reduces extracellular acidification rate (ECAR), an indicator of enhanced glycolysis, required for cell migration. Quercetin treatment suppresses vimentin phosphorylation at lower concentrations, a critical step in cell migration, further proving its potential against cell migration. Phosphorylation of Vimentin is also crucial in the protection of vimentin from caspase-mediated proteolysis. Interestingly, quercetin activates caspase-3 at higher concentrations; hence, total vimentin levels were investigated, and caspase-3 mediated proteolysis of vimentin was observed. Vimentin and glycolysis are essential features of the mesenchymal state, which is required to maintain CSCs. Ours data also suggests quercetin mediated reduction in CSCs population. ConclusionWe report a novel mechanism of quercetin mediated inhibition of NPA cells migration by suppressing vimentin phosphorylation and subsequent proteolysis. Collectively our data suggest the potential of quercetin as an innovative anti-cancer therapeutic agent for PTC management.

Targeting therapy-resistant lung cancer stem cells via disruption of the AKT/TSPYL5/PTEN positive-feedback loop

Cancer stem cells (CSCs) are regarded as essential targets to overcome tumor progression and therapeutic resistance; however, practical targeting approaches are limited. Here, we identify testis-specific Y-like protein 5 (TSPYL5) as an upstream regulator of CSC-associated genes in non-small cell lung cancer cells, and suggest as a therapeutic target for CSC elimination. TSPYL5 elevation is driven by AKT-dependent TSPYL5 phosphorylation at threonine-120 and stabilization via inhibiting its ubiquitination. TSPYL5-pT120 also induces nuclear translocation and functions as a transcriptional activator of CSC-associated genes, ALDH1 and CD44. Also, nuclear TSPYL5 suppresses the transcription of PTEN, a negative regulator of PI3K signaling. TSPYL5-pT120 maintains persistent CSC-like characteristics via transcriptional activation of CSC-associated genes and a positive feedback loop consisting of AKT/TSPYL5/PTEN signaling pathway. Accordingly, elimination of TSPYL5 by inhibiting TSPYL5-pT120 can block aberrant AKT/TSPYL5/PTEN cyclic signaling and TSPYL5-mediated cancer stemness regulation. Our study suggests TSPYL5 be an effective target for therapy-resistant cancer.

The impact of fusion genes on cancer stem cells and drug resistance.

With ever increasing evidences on the role of fusion genes as the oncogenic protagonists in myriad cancers, it's time to explore if fusion genes can be the next generational drug targets in meeting the current demands of higher drug efficacy. Eliminating cancer stem cells (CSC) has become the current focus; however, we have reached a standstill in drug development owing to the lack of effective strategies to eradicate CSC. We believe that fusion genes could be the novel targets to overcome this limitation. The intriguing feature of fusion genes is that it dominantly impacts every aspect of CSC including self-renewal, differentiation, lineage commitment, tumorigenicity and stemness. Given the clinical success of fusion gene-based drugs in hematological cancers, our attempt to target fusion genes in eradicating CSC can be rewarding. As fusion genes are expressed explicitly in cancer cells, eradicating CSC by targeting fusion genes provides yet an another advantage of negligible patient side effects since normal cells remain unaffected by the drug. We hereby delineate the latest evidences on how fusion genes regulate CSC and drug resistance.

Nanoscale Formulations: Incorporating Curcumin into Combination Strategies for the Treatment of Lung Cancer.

Lung cancer remains the most common cancer worldwide. Although significant advances in screening have been made and early diagnosis strategies and therapeutic regimens have been developed, the overall survival rate remains bleak. Curcumin is extracted from the rhizomes of turmeric and exhibits a wide range of biological activities. In lung cancer, evidence has shown that curcumin can markedly inhibit tumor growth, invasion and metastasis, overcome resistance to therapy, and even eliminate cancer stem cells (CSCs). Herein, the underlying molecular mechanisms of curcumin were summarized by distinct biological processes. To solve the limiting factors that curtail the clinical applications of curcumin, nanoformulations encapsulating curcumin were surveyed in detail. Nanoparticles, including liposomes, micelles, carbon nanotubes (CNTs), solid lipid nanoparticles (SLNs), nanosuspensions, and nanoemulsions, were explored as proper carriers of curcumin. Moreover, it was firmly verified that curcumin has the ability to sensitize lung cancer cells to chemotherapeutic drugs, such as cisplatin and docetaxel, and to various targeted therapies. Regarding the advantages and drawbacks of curcumin, we concluded that combination therapy based on nanoparticles would be the optimal approach to broaden the application of curcumin in the clinic in the near future.

Repurposing Chloroquine Analogs as an Adjuvant Cancer Therapy.

Drug repurposing is emerging as an attractive strategy with lower attrition rate, lower cost and shorter timeframe than traditional drug discovery methods. Chloroquine (CQ) and its analogs are old drugs originally indicated for malaria treatment. Serendipitous discovery in early years revealed its anti-inflammatory properties, thus allowing its repositioned use in autoimmune diseases. Recent evidence also suggested its potential therapeutic use for anticancer therapy. This article reviews the molecular mechanisms, clinical evaluation and recent patents of CQ analogs in cancer therapy. Literature and patent searches were conducted using PubMed database and Google Patent/ USPTO Patent Search database, respectively. The keywords including "chloroquine", "hydroxychloroquine", "chloroquine analogs", "chloroquine derivatives", "repurposing", "autophagy", and "cancer" were used. CQ analogs have been reported to elicit their anticancer effects by modulating autophagy, inducing apoptosis, eliminating cancer stem cells, normalizing tumor vasculature and modulating antitumor immunity. As documented by recent patents and clinical trials, CQ analogs have been repurposed as an adjuvant therapy and combined with other anticancer agents for synergistic enhancement of treatment efficacy. However, most clinical trials on CQ only demonstrated modest improvement in anti-cancer efficacy. Given that CQ loses its anticancer activity in acidic and hypoxic environment within a tumor, novel CQ analogs and/or their formulations are under active investigation to improve their physicochemical properties and biological activity. On the other hand, identification of new biomarkers for better patient selection has been advocated in future trials in order to realize the repurposing of CQ analogs for cancer treatment in a personalized manner.

PIK3C3 Inhibition Promotes Sensitivity to Colon Cancer Therapy by Inhibiting Cancer Stem Cells.

Simple SummaryColorectal cancer (CRC) represents a heterogeneous population of tumor cells and cancer stem cells (CSCs) where CSCs are postulated to resist the chemotherapy, and support cancer malignancy. Eliminating CSC can therefore improve CRC therapy and patient survival; however, such strategies have not yielded the desired outcome. Inhibiting autophagy has shown promise in suppressing therapy resistance; however, current autophagy inhibitors have failed in the clinical trials. In the current study, we provided data supporting the efficacy of 36-077, a potent inhibitor of PIK3C3/VPS34, in inhibiting autophagy to kill the CSC to promote the efficacy of colon cancer therapy.Background: Despite recent advances in therapies, resistance to chemotherapy remains a critical problem in the clinical management of colorectal cancer (CRC). Cancer stem cells (CSCs) play a central role in therapy resistance. Thus, elimination of CSCs is crucial for effective CRC therapy; however, such strategies are limited. Autophagy promotes resistance to cancer therapy; however, whether autophagy protects CSCs to promote resistance to CRC-therapy is not well understood. Moreover, specific and potent autophagy inhibitors are warranted as clinical trials with hydroxychloroquine have not been successful. Methods: Colon cancer cells and tumoroids were used. Fluorescent reporter-based analysis of autophagy flux, spheroid and side population (SP) culture, and qPCR were done. We synthesized 36-077, a potent inhibitor of PIK3C3/VPS34 kinase, to inhibit autophagy. Combination treatments were done using 5-fluorouracil (5-FU) and 36-077. Results: The 5-FU treatment induced autophagy only in a subset of the treated colon cancer. These autophagy-enriched cells also showed increased expression of CSC markers. Co-treatment with 36-077 significantly improved efficacy of the 5-FU treatment. Mechanistic studies revealed that combination therapy inhibited GSK-3β/Wnt/β-catenin signaling to inhibit CSC population. Conclusion: Autophagy promotes resistance to CRC-therapy by specifically promoting GSK-3β/Wnt/β-catenin signaling to promote CSC survival, and 36-077, a PIK3C3/VPS34 inhibitor, helps promote efficacy of CRC therapy.

Combination of PKCδ Inhibition with Conventional TKI Treatment to Target CML Models.

Simple SummaryThe tyrosine kinase inhibitor (TKI) imatinib was the first targeted therapy to show clinical efficacy against chronic myeloid leukemia (CML) through inhibition of the breakpoint cluster region–Abelson murine leukemia viral oncogene homolog (BCR-ABL), which is responsible for the disease. Two other generations of TKIs have succeeded imatinib, offering additional therapeutic solutions for a growing number of patients with imatinib-resistant CML. However, these clinical approaches although very effective, generate many unwanted side effects because of their daily administration. Attempts to stop TKI when the disease is no longer detectable at the molecular level, unfortunately result in relapses in more than half of cases. This highlights the presence of undetectable leukemia cells, recognized as leukemic stem cells (LSCs) that are TKI insensitive. It therefore appears necessary to identify new biochemical pathways in LSCs, the targeting of which would make re-sensitization to TKIs possible. The results presented here demonstrate that targeting the protein kinase Cδ (PKCδ) pathway represents a valid alternative for LSC elimination.Numerous combinations of signaling pathway blockades in association with tyrosine kinase inhibitor (TKI) treatment have been proposed for eradicating leukemic stem cells (LSCs) in chronic myeloid leukemia (CML), but none are currently clinically available. Because targeting protein kinase Cδ (PKCδ) was demonstrated to eliminate cancer stem cells (CSCs) in solid tumors, we evaluated the efficacy of PKCδ inhibition in combination with TKIs for CML cells. We observed that inhibition of PKCδ by a pharmacological inhibitor, by gene silencing, or by using K562 CML cells expressing dominant-negative (DN) or constitutively active (CA) PKCδ isoforms clearly points to PKCδ as a regulator of the expression of the stemness regulator BMI1. As a consequence, inhibition of PKCδ impaired clonogenicity and cell proliferation for leukemic cells. PKCδ targeting in K562 and LAMA-84 CML cell lines clearly enhanced the apoptotic response triggered by any TKI. A strong synergism was observed for apoptosis induction through an increase in caspase-9 and caspase-3 activation and significantly decreased expression of the Bcl-xL Bcl-2 family member. Inhibition of PKCδ did not modify BCR-ABL phosphorylation but acted downstream of the oncogene by downregulating BMI1 expression, decreasing clonogenicity. PKCδ inhibition interfered with the clonogenicity of primary CML CD34+ and BCR-ABL-transduced healthy CD34+ cells as efficiently as any TKI while it did not affect differentiation of healthy CD34+ cells. LTC-IC experiments pinpointed that PKCδ inhibition strongly decreased the progenitors/LSCs frequency. All together, these results demonstrate that targeting of PKCδ in combination with a conventional TKI could be a new therapeutic opportunity to affect for CML cells.

Introductions to the community: Early-career researchers in the time of COVID-19.

COVID-19 has unfortunately halted lab work, conferences, and in-person networking, which is especially detrimental to researchers just starting their labs. Through social media and our reviewer networks, we met some early-career stem cell investigators impacted by the closures. Here, they introduce themselves and their research to our readers.

Efficacy of the new therapeutic approach in curing malignant neoplasms on the model of human glioblastoma.

Objective:Glioma is a highly invasive tumor, frequently disposed in essential areas of the brain, which makes its surgical excision extremely difficult; meanwhile adjuvant therapy remains quite ineffective.Methods:In the current report, a new therapeutic approach in curing malignant neoplasms has been performed on the U87 human glioblastoma model. This approach, termed “Karanahan”, is aimed at the eradication of cancer stem cells (CSCs), which were recently shown to be capable of internalizing fragments of extracellular double-stranded DNA. After being internalized, these fragments interfere in the process of repairing interstrand cross-links caused by exposure to appropriate cytostatics, and such an interference results either in elimination of CSCs or in the loss of their tumorigenic potency. Implementation of the approach requires a scheduled administration of cytostatic and complex composite double-stranded DNA preparation.Results:U87 cells treated in vitro in accordance with the Karanahan approach completely lost their tumorigenicity and produced no grafts upon intracerebral transplantation into immunodeficient mice. In SCID mice with developed subcutaneous grafts, the treatment resulted in reliable slowing down of tumor growth rate (P < 0.05). In the experiment with intracerebral transplantation of U87 cells followed by surgical excision of the developed graft and subsequent therapeutic treatment, the Karanahan approach was shown to reliably slow down the tumor growth rate and increase the median survival of the mice twofold relative to the control.Conclusions:The effectiveness of the Karanahan approach has been demonstrated both in vitro and in vivo in treating developed subcutaneous grafts as well as orthotopic grafts after surgical excision of the tumor.

Therapeutic targeting of pancreatic cancer stem cells by dexamethasone modulation of the MKP-1–JNK axis

Postoperative recurrence from microscopic residual disease must be prevented to cure intractable cancers, including pancreatic cancer. Key to this goal is the elimination of cancer stem cells (CSCs) endowed with tumor-initiating capacity and drug resistance. However, current therapeutic strategies capable of accomplishing this are insufficient. Using in vitro models of CSCs and in vivo models of tumor initiation in which CSCs give rise to xenograft tumors, we show that dexamethasone induces expression of MKP-1, a MAPK phosphatase, via glucocorticoid receptor activation, thereby inactivating JNK, which is required for self-renewal and tumor initiation by pancreatic CSCs as well as for their expression of survivin, an anti-apoptotic protein implicated in multidrug resistance. We also demonstrate that systemic administration of clinically relevant doses of dexamethasone together with gemcitabine prevents tumor formation by CSCs in a pancreatic cancer xenograft model. Our study thus provides preclinical evidence for the efficacy of dexamethasone as an adjuvant therapy to prevent postoperative recurrence in patients with pancreatic cancer.

Immune Remodeling of the Extracellular Matrix Drives Loss of Cancer Stem Cells and Tumor Rejection.

The nature of the tumor microenvironment (TME) influences the ability of tumor-specific T cells to control tumor growth. In this study, we performed an unbiased comparison of the TME of regulatory T-cell (Treg)-replete and Treg-depleted carcinogen-induced tumors, including Treg-depleted responding (regressing) and non-responding (growing) tumors. This analysis revealed an inverse relationship between extracellular matrix (ECM) and T-cell infiltrates where responding tumors were T-cell rich and ECM poor, whereas the converse was observed in non-responder tumors. For this reason, we hypothesized that the ECM acted as a barrier to successful T-cell infiltration and tumor rejection. However, further experiments revealed that this was not the case but instead showed that an effective T-cell response dramatically altered the density of ECM in the TME. Along with loss of ECM and high numbers of infiltrating T cells, responder tumors were distinguished by the development of lymphatic and blood vessel networks with specialized immune function. ECM-rich tumors exhibited a stem cell-like gene expression profile and superior tumor-initiating capacity, whereas such features were absent in responder tumors. Overall, these findings define an extended role for an effective immune response, not just in direct killing of tumor cells but in widescale remodeling of the TME to favor loss of ECM, elimination of cancer stem cells, and propagation of adaptive immunity.

Mitochondrial rewiring through mitophagy and mitochondrial biogenesis in cancer stem cells: A potential target for anti-CSC cancer therapy.

Cancer stem cells (CSCs) are distinct subpopulations of cancer cells with stem cell-like abilities and are more resilient to chemotherapy, causing tumor relapse. Mitophagy, a selective form of autophagy, removes damaged unwanted mitochondria from cells through a lysosome-based degradation pathway to maintain cellular homeostasis. CSCs use mitophagy as a chief survival response mechanism for their growth, propagation, and tumorigenic ability. Mitochondrial biogenesis is a crucial cellular event replacing damaged mitochondria through the coordinated regulation of several transcription factors to achieve the bioenergetic demands of the cell. Because of the high mitochondrial content in CSCs, mitochondrial biogenesis is an interesting target to address the resistance mechanisms of anti-CSC therapy. However, to what extent both mitophagy and mitochondrial biogenesis are vital in promoting stemness, metabolic reprogramming, and drug resistance in CSCs has yet to be established. Therefore, in this review, we focus on understanding the interesting aspects of mitochondrial rewiring that involve mitophagy and mitochondrial biogenesis in CSCs. We also discuss their coordinated regulation in the elimination of CSCs, with respect to stemness and differentiation of the CSC phenotype, and the different aspects of tumorigenesis such as cancer initiation, progression, resistance, and tumor relapse. Finally, we address several other unanswered questions relating to targeted anti-CSC cancer therapy, which improves patient survival.

Targeting poor proteasomal function with radioiodine eliminates CT26 colon cancer stem cells resistant to bortezomib therapy

We tested the hypothesis that tumor response to conventional bortezomib (BTZ) treatment is enhanced by targeted radiotherapy of resistant cancer stem cells (CSCs) that have characteristically poor proteasome function. This was accomplished by augmenting 131I uptake through expression of a sodium-iodide symporter (NIS) fusion protein that accumulates in cells with low proteasome activity. The NIS gene fused with the C-terminal of ornithine decarboxylase degron (NIS-cODC) was cloned. Stably expressing CT26/NIS-cODC cells and tumorsphere-derived CSCs were evaluated for NIS expression and radioiodine uptake. CT26/NIS-cODC cells implanted into mice underwent PET imaging, and tumor-bearing mice were treated with BTZ alone or with BTZ plus 131I. CT26/NIS-cODC cells accumulated NIS protein, which led to high radioiodine uptake when proteasome activity was inhibited or after enrichment for stemness. The cell population that survived BTZ treatment was enriched with CSCs that were susceptible to 131I treatment, which suppressed stemness features. Positron emission tomography and uptake measurements confirmed high 124I and 131I uptake of CT26/NIS-cODC CSCs implanted in living mice. In CT26/NIS-cODC tumor-bearing mice, whereas BTZ treatment modestly retarded tumor growth and increased stemness markers, combining 131I therapy suppressed stemness features and achieved greater antitumor effects. The NIS-cODC system offer radioiodine-targeted elimination of CSCs that are tolerant to proteasome inhibition therapy.

Increasing the colon cancer cells sensitivity toward radiation therapy via application of Oct4-Sox2 complex decoy oligodeoxynucleotides.

Low sensitivity of cancer stem cells toward regular cancer therapy strategies is an important issue in the field of cancer remedy. The concept of cancer stem cell elimination has been a topic of interest in the field of molecular medicine for a long time. At the current study, it was aimed to elevate the sensitivity of cancer stem-like cells toward radiotherapy by treating with Oct4-Sox2 complex decoy oligodeoxynucleotides (ODNs). After treating HT29 and HT29-ShE cells with Oct4-Sox2 complex decoy ODNs, and analyzing the cellular uptake and localization of decoys, treated cells and control groups were subjected to irradiation by fractionated 6MV X-ray with a final dose of 2Gy. Thereafter, the influence of radiotherapy on ODNs treated groups and control group was investigated on cell viability, cell cycle, apoptosis, colonosphere formation and scratch assay. Cellular uptake and localization assays demonstrated that decoy ODNs can efficiently be transfected to the cells and reside in subcellular compartment, where they pose their action on gene regulation. Post radiotherapy analysis indicated statistical significance in decoy ODNs treated cells by means of lower cell viability, cell cycle arrest in G2/M phase, increased cellular apoptosis,and reduced cell motility. Also, formed colonospheres were smaller in size and fewer in numbers. Considering the role of Oct4, and Sox2 transcription factors in signaling pathways of preserving stemness and inducing reverse EMT, application of decoy strategy could increasethe sensitivity of cancer cells toward irradiation, which has a potential to eliminate the cancerous cells fromtumors andsupport cancer treatment.

Therapeutic Targeting of Signaling Pathways Related to Cancer Stemness.

The theory of cancer stem cells (CSCs) proposes that the different cells within a tumor, as well as metastasis deriving from it, are originated from a single subpopulation of cells with self-renewal and differentiation capacities. These cancer stem cells are supposed to be critical for tumor expansion and metastasis, tumor relapse and resistance to conventional therapies, such as chemo- and radiotherapy. The acquisition of these abilities has been attributed to the activation of alternative pathways, for instance, WNT, NOTCH, SHH, PI3K, Hippo, or NF-κB pathways, that regulate detoxification mechanisms; increase the metabolic rate; induce resistance to apoptotic, autophagic, and senescence pathways; promote the overexpression of drug transporter proteins; and activate specific stem cell transcription factors. The elimination of CSCs is an important goal in cancer therapeutic approaches because it could decrease relapses and metastatic dissemination, which are main causes of mortality in oncology patients. In this work, we discuss the role of these signaling pathways in CSCs along with their therapeutic potential.

Apigenin Enhanced Antitumor Effect of Cisplatin in Lung Cancer via Inhibition of Cancer Stem Cells

Cancer stem cell theory has been proposed to explain tumor heterogeneity and the carcinogenesis process. Highly tumorigenic lung cancer stem cells develop resistance to cisplatin (CDDP), a common chemotherapy drug. Herein, we attempted to clarify whether apigenin (API) can improve the antitumor efficiency of CDDP in lung cancer using cancer stem cells. Lung cancer stem cells were identified as CD 133 positive cancer cells in non-small cell lung cancer (NSCLC) A549, H1299 cells and CDDP-resistant NSCLC A549R cells. The cytotoxic effect of API was measured in CDDP-treated A549, H1299, and A549R cells. API repressed CD 133 positive cells and enhanced the antitumor effect of CDDP in A549, H1299, and A549R cells. The synergistic antitumor effect of API and CDDP was blocked by addition of the p53 inhibitor Pifithrin-α, and siRNA targeting the p53 gene in A549R cells. Furthermore, API eliminates CDDP-induced CSC via p53, since A549R cells lacking p53 and Pifithrin-α addition derepressed the decrease in CD 133 positive cells after API treatment in CDDP-treated A549 and A549R cells. The findings indicate that API might eliminate cancer stem cells and enhance the antitumor effects of CDDP in NSCLC via p53.

Cancer Chemopreventive Activities of Silibinin on Colorectal Cancer through Regulation of E-Cadherin/β-Catenin Pathway

Purpose Silibinin is the most active flavonolignan constituent of Silymarin, the extract of milk thistle seeds. In this study, we investigated the anticancer properties and molecular mechanisms of silibinin on colorectal cancer (CRC) cells. Methods HCT-116 cells were used to investigate the effects of silibinin on proliferation, migration, epithelial-mesenchymal transition (EMT), cancer stem cells (CSCs), apoptosis and signaling pathways underlying these functions by using 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) and colony formation assay, quantitative reverse-transcription polymerase chain reaction (RT-qPCR), Western blot, Acridine orange/propidium iodide double staining, migration and sphere formation assay. Results Silibinin significantly suppressed HCT-116 cells proliferation and migration and induced the apoptosis via increasing the Bax/Bcl-2 ratio. Silibinin down-regulated cancer stemness markers; prominin-1 (CD133), CD44, BMI1, Aldehyde dehydrogenase 1 (ALDH1), and doublecortin-like kinase 1 (DCLK1) of HCT-116 cell line. Silibinin attenuated EMT through decreased expression of N- cadherin and vimentin and increased expression of (E-cadherin). Furthermore, silibinin decreased the β-catenin gene and protein expression. Conclusion Our study revealed that silibinin maintains various antitumor activities such as induction of apoptosis, suppression of migration, elimination of CSCs and attenuation of EMT related markers in CRC cells. These underlying anti-tumor mechanisms of silibinin are likely to act through the blockage of the β-catenin signaling pathway, which is the key component of Wnt signaling pathway, one of the hallmarks of CRC development.

Antisense oligonucleotides targeting lncRNA AC104041.1 induces antitumor activity through Wnt2B/\u03b2-catenin pathway in head and neck squamous cell carcinomas

Long non-coding RNAs (lncRNAs) contribute to the initiation and progression of various tumors, including head and neck squamous carcinoma (HNSCC), which is a common malignancy with high morbidity and low survival rate. However, the mechanism of lncRNAs in HNSCC tumorigenesis remains largely unexplored. In this work, we identified a novel lncRNA AC104041.1 which is highly upregulated and correlated with poor survival in HNSCC patients. Moreover, AC104041.1 overexpression significantly promoted tumor growth and metastasis of HNSCC in vitro and in vivo. Mechanistically, AC104041.1 mainly located in the cytoplasm and could function as ceRNA (competing endogenous RNA) for miR-6817-3p, thereby stabilized Wnt2B, and consequently inducing β-catenin nuclear translocation and activation. Moreover, we demonstrate that salinomycin, which as a highly effective antibiotic in the elimination of cancer stem cells through the Wnt/β-catenin signaling, could enhance the inhibition of tumor growth by antisense oligonucleotides (ASO) targeting AC104041.1 in HNSCC cells and PDXs (patient-derived xenograft) model. Thus, our data provide preclinical evidence to support a novel strategy of ASOs targeting AC104041.1 in combination with salinomycin and may as a beneficial treatment approach for HNSCC.

The Relevance of Transcription Factors in Gastric and Colorectal Cancer Stem Cells Identification and Eradication.

Gastric and colorectal cancers have a high incidence and mortality worldwide. The presence of cancer stem cells (CSCs) within the tumor mass has been indicated as the main reason for tumor relapse, metastasis and therapy resistance, leading to poor overall survival. Thus, the elimination of CSCs became a crucial goal for cancer treatment. The identification of these cells has been performed by using cell-surface markers, a reliable approach, however it lacks specificity and usually differs among tumor type and in some cases even within the same type. In theory, the ideal CSC markers are those that are required to maintain their stemness features. The knowledge that CSCs exhibit characteristics comparable to normal stem cells that could be associated with the expression of similar transcription factors (TFs) including SOX2, OCT4, NANOG, KLF4 and c-Myc, and signaling pathways such as the Wnt/β-catenin, Hedgehog (Hh), Notch and PI3K/AKT/mTOR directed the attention to the use of these similarities to identify and target CSCs in different tumor types. Several studies have demonstrated that the abnormal expression of some TFs and the dysregulation of signaling pathways are associated with tumorigenesis and CSC phenotype. The disclosure of common and appropriate biomarkers for CSCs will provide an incredible tool for cancer prognosis and treatment. Therefore, this review aims to gather the new insights in gastric and colorectal CSC identification specially by using TFs as biomarkers and divulge promising drugs that have been found and tested for targeting these cells.