Oct-4 is required for an antiapoptotic behavior of chemoresistant colorectal cancer cells enriched for cancer stem cells: effects associated with STAT3/Survivin

Clinical Significance of Overexpression of Oct4 in Advanced Stage Gallbladder Carcinoma

BACKGROUND

Oct4 has critical role in maintaining pluripotency, proliferative potential, and self-renewal capacity in embryonic stem and germ cells. Although Oct4 has been shown to be upregulated in many cancers, its clinical significance in gallbladder carcinoma is poorly understood.

METHODS

We studied the expression profile of Oct4 in 61 GBC and 30 chronic cholecystitis (as control) using real time RT-PCR, western blotting, and immunohistochemistry. The expression data was correlated with clinico-pathological parameters. The diagnostic utility was assessed through ROC curve, and prognostic value was analyzed by Kaplan-Meier method.

RESULTS

Oct4 was significantly upregulated at mRNA as well as protein levels. The higher mRNA expression shows significant association with late stage, late T stage, and higher grade of tumor. A significant positive correlation was also observed with stage, T stage, and tumor grade. Sum score analysis of protein expression shows positive correlation with stage and the presence or absence of gallstone in tumor samples. The ROC curve analysis revealed the moderate diagnostic potential of Oct4. Kaplan-Meier analysis showed that patients having higher expression of Oct4 were having low mean survival compared with the patients with lower Oct4 expression.

CONCLUSION

In conclusion, our data suggests that higher expression of Oct4 may serve as potential biological indicator for tumor aggressiveness and poor prognosis of GBC.

STAT3 as a newly emerging target in colorectal cancer therapy: Tumorigenesis, therapy response, and pharmacological/nanoplatform strategies

Colorectal cancer (CRC) ranks as the third most aggressive tumor globally, and it can be categorized into two forms: colitis-mediated CRC and sporadic CRC. The therapeutic approaches for CRC encompass surgical intervention, chemotherapy, and radiotherapy. However, even with the implementation of these techniques, the 5-year survival rate for metastatic CRC remains at a mere 12-14%. In the realm of CRC treatment, gene therapy has emerged as a novel therapeutic approach. Among the crucial molecular pathways that govern tumorigenesis, STAT3 plays a significant role. This pathway is subject to regulation by cytokines and growth factors. Once translocated into the nucleus, STAT3 influences the expression levels of factors associated with cell proliferation and metastasis. Literature suggests that the upregulation of STAT3 expression is observed as CRC cells progress towards metastatic stages. Consequently, elevated STAT3 levels serve as a significant determinant of poor prognosis and can be utilized as a diagnostic factor for cancer patients. The biological and malignant characteristics of CRC cells contribute to low survival rates in patients, as the upregulation of STAT3 prevents apoptosis and promotes pro-survival autophagy, thereby accelerating tumorigenesis. Furthermore, STAT3 plays a role in facilitating the proliferation of CRC cells through the stimulation of glycolysis and promoting metastasis via the induction of epithelial-mesenchymal transition (EMT). Notably, an intriguing observation is that the upregulation of STAT3 can mediate resistance to 5-fluorouracil, oxaliplatin, and other anti-cancer drugs. Moreover, the radio-sensitivity of CRC diminishes with increased STAT3 expression. Compounds such as curcumin, epigallocatechin gallate, and other anti-tumor agents exhibit the ability to suppress STAT3 and its associated pathways, thereby impeding tumorigenesis in CRC. Furthermore, it is worth noting that nanostructures have demonstrated anti-proliferative and anti-metastatic properties in CRC.

Expression of OCT4 isoforms is reduced in primary colorectal cancer

Introduction

Colorectal cancer (CRC) is one of the most common types of cancer worldwide. The carcinogenesis of CRC is indeed complex, and there are many different mechanisms and pathways that contribute to the development of malignancy and the progression from primary to metastatic tumors. The OCT4A, encoded by the POU5F1 gene, is a transcription factor responsible for the phenotype of stem cells, maintaining pluripotency and regulation of differentiation. The POU5F1 gene is made up of five exons that can create numerous isoforms through alternative promoter or alternative splicing. In addition to OCT4A, other isoforms called OCT4B are also translated into protein; however, their role in cells has been unclear. The aim of our work was to investigate the expression patterns of OCT4 isoforms in primary and metastatic CRC, providing us with useful information about their role in the development and progression of CRC.

Methods

Surgical specimens from a total of 78 patients were collected and isolated from primary tumors (n = 47) and metastases (n = 31). The relative gene expression of OCT4 isoforms was investigated using the RT-qPCR method together with the TaqMan probes for particular OCT4 isoforms.

Results

Our results suggest significantly downregulated expression of the OCT4A and OCT4Bs isoforms in both primary (p = 0.0002 and p < 0.0001, respectively) and metastatic tumors (p = 0.0006 and p = 0.00051, respectively) when compared with the control samples. We also observed a correlation between reduced expression of all OCT4 isoforms and both primary and left-sided tumors (p = 0.001 and p = 0.030, respectively). On the other hand, the expression of all OCT4 isoforms was significantly upregulated in metastases compared with primary tumors (p < 0.0001).

Discussion

Unlike previous reports, we found out that the expression of OCT4A, OCT4Bs, and all OCT4 isoforms was significantly reduced in primary tumors and metastases compared with control samples. On the other hand, we supposed that the expression rate of all OCT4 isoforms may be related to the cancer type and side, as well as to liver metastases. However, further studies are required to investigate the detailed expression patterns and significance of individual OCT4 isoforms in carcinogenesis.

Melatonin and 5-fluorouracil combination chemotherapy: opportunities and efficacy in cancer therapy

Combined chemotherapy is a treatment method based on the simultaneous use of two or more therapeutic agents; it is frequently necessary to produce a more effective treatment for cancer patients. Such combined treatments often improve the outcomes over that of the monotherapy approach, as the drugs synergistically target critical cell signaling pathways or work independently at different oncostatic sites. A better prognosis has been reported in patients treated with combination therapy than in patients treated with single drug chemotherapy. In recent decades, 5-fluorouracil (5-FU) has become one of the most widely used chemotherapy agents in cancer treatment. This medication, which is soluble in water, is used as the first line of anti-neoplastic agent in the treatment of several cancer types including breast, head and neck, stomach and colon cancer. Within the last three decades, many studies have investigated melatonin as an anti-cancer agent; this molecule exhibits various functions in controlling the behavior of cancer cells, such as inhibiting cell growth, inducing apoptosis, and inhibiting invasion. The aim of this review is to comprehensively evaluate the role of melatonin as a complementary agent with 5-FU-based chemotherapy for cancers. Additionally, we identify the potential common signaling pathways by which melatonin and 5-FU interact to enhance the efficacy of the combined therapy. Video abstract.

Revisiting the Anti-Cancer Toxicity of Clinically Approved Platinating Derivatives

Cisplatin (CDDP), carboplatin (CP), and oxaliplatin (OXP) are three platinating agents clinically approved worldwide for use against a variety of cancers. They are canonically known as DNA damage inducers; however, that is only one of their mechanisms of cytotoxicity. CDDP mediates its effects through DNA damage-induced transcription inhibition and apoptotic signalling. In addition, CDDP targets the endoplasmic reticulum (ER) to induce ER stress, the mitochondria via mitochondrial DNA damage leading to ROS production, and the plasma membrane and cytoskeletal components. CP acts in a similar fashion to CDDP by inducing DNA damage, mitochondrial damage, and ER stress. Additionally, CP is also able to upregulate micro-RNA activity, enhancing intrinsic apoptosis. OXP, on the other hand, at first induces damage to all the same targets as CDDP and CP, yet it is also capable of inducing immunogenic cell death via ER stress and can decrease ribosome biogenesis through its nucleolar effects. In this comprehensive review, we provide detailed mechanisms of action for the three platinating agents, going beyond their nuclear effects to include their cytoplasmic impact within cancer cells. In addition, we cover their current clinical use and limitations, including side effects and mechanisms of resistance.

Inside the stemness engine: Mechanistic links between deregulated transcription factors and stemness in cancer

Cell identity is largely determined by its transcriptional profile. In tumour, deregulation of transcription factor expression and/or activity enables cancer cell to acquire a stem-like state characterised by capacity to self-renew, differentiate and form tumours in vivo. These stem-like cancer cells are highly metastatic and therapy resistant, thus warranting a more complete understanding of the molecular mechanisms downstream of the transcription factors that mediate the establishment of stemness state. Here, we review recent research findings that provide a mechanistic link between the commonly deregulated transcription factors and stemness in cancer. In particular, we describe the role of master transcription factors (SOX, OCT4, NANOG, KLF, BRACHYURY, SALL, HOX, FOX and RUNX), signalling-regulated transcription factors (SMAD, β-catenin, YAP, TAZ, AP-1, NOTCH, STAT, GLI, ETS and NF-κB) and unclassified transcription factors (c-MYC, HIF, EMT transcription factors and P53) across diverse tumour types, thereby yielding a comprehensive overview identifying shared downstream targets, highlighting unique mechanisms and discussing complexities.

Gemcitabine: An Alternative Treatment for Oxaliplatin-Resistant Colorectal Cancer

Resistance to treatments is one of the leading causes of cancer therapy failure. Oxaliplatin is a standard chemotherapy used to treat metastatic colorectal cancer. However, its efficacy is greatly reduced by the development of resistances. In a previous study, we deciphered the mechanisms leading to oxaliplatin resistance and highlighted the roles played by ROS production and the p38 MAPK pathway in this phenomenon. In this report, we studied the effects of different chemotherapy molecules on our oxaliplatin-resistant cells to identify alternative treatments. Among all the studied molecules, gemcitabine was the only one to present a major cytotoxic effect on oxaliplatin-resistant cancer cells both in vivo and in vitro. However, the combination of oxaliplatin and gemcitabine did not present any major interest. Indeed, the study of combination efficiency using Chou and Talalay's method showed no synergy between oxaliplatin and gemcitabine. Using PamGene technology to decipher gemcitabine's effects on oxaliplatin-resistant cells, we were able to show that gemcitabine counteracts chemoresistance by strongly inhibiting the Akt and src/p38 MAPK pathways, leading to apoptosis induction and cell death. In view of these results, gemcitabine could be an interesting alternative therapy for patients with colorectal cancer not responding to oxaliplatin-based protocols such as FOLFOX.

Curcumin inhibits the cancer‑associated fibroblast‑derived chemoresistance of gastric cancer through the suppression of the JAK/STAT3 signaling pathway

The present study aimed to investigate whether the Janus-activated kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) signaling pathway is a critical mechanism underlying the cancer-associated fibroblast (CAF)-induced chemoresistance of gastric cancer (GC). In addition, the present study tried to suggest a natural product to compromise the effects of CAF on the chemoresistance of GC. The results of cell proliferation assay revealed that the conditioned medium (CM) collected from CAFs further increased resistance to 5-fluorouracil (5-FU) in GC cell lines. Secretome analysis revealed that the levels of several secreted proteins, including C-C motif chemokine ligand 2, C-X-C motif chemokine ligand 1, interleukin (IL)-6 and IL-8, were increased in the CM from CAFs co-cultured with cancer cells compared to CM from cancer cells. Western blot analysis revealed that CAFs activated the JAK/STAT3 signaling pathway in cancer cells. The experimental models revealed that curcumin abrogated the CAF-mediated activation of the JAK/STAT3 signaling pathway in GC cells. In vivo data revealed the synergistic effects of curcumin with 5-FU treatment in xenograft GC tumors. These data strongly suggest that the suppression of the JAK/STAT3 signaling pathway counteracts the CAF-induced chemoresistance of GC cells. It is suggested that curcumin may be a suitable natural product which may be used to overcome chemoresistance by inhibiting the CAF-induced activation of the JAK/STAT3 signaling pathway in GC.

5-fluorouracil treatment of patient-derived scaffolds from colorectal cancer reveal clinically critical information

BACKGROUND

Colorectal cancer is a commonly diagnosed cancer worldwide. Unfortunately, many patients do not respond to standard chemotherapy treatments and develop disease relapse and metastases. Besides cancer cell specific genetic changes, heterogeneity in the tumor microenvironment contribute to the clinical presentation of the disease and can potentially also influence drug resistance. By using a recently developed patient-derived scaffold method monitoring how a standardized reporter cancer cell line adapts to various microenvironments treated with chemotherapy, we wanted to clarify how individual patient specific microenvironments influence the chemotherapy response in colorectal cancer.

METHODS

Surgically resected colorectal cancer specimens from 89 patients were decellularized to produce patient-derived scaffold, which were seeded with HT29 cells, cultured for 3 weeks, and treated with 5-fluorouracil. Gene expression changes of adapted and treated HT29 cells were monitored by qPCR and compared with clinical parameters including disease-free survival.

RESULTS

The effects of 5-fluorouracil treatment varied between different patient-derived scaffold, but generally induced a reduced expression of proliferation genes and increased expression of pluripotency and epithelial-to-mesenchymal transition genes. Interestingly, patient-derived scaffold cultures obtained from patients with disease recurrences showed a significantly less pronounced anti-proliferative effect of 5-fluorouracil and more pronounced increase of pluripotency, with MKI67 and POU5F1 being among the most significant genes linked to disease relapse in colorectal cancer.

CONCLUSIONS

Colorectal patient-derived scaffold can decode clinically relevant tumor microenvironmental influence of 5-fluorouracil treatment effects opening up for optimized precision medicine in colorectal cancer treatment.

The Pro-Survival Oct4/Stat1/Mcl-1 Axis Is Associated with Poor Prognosis in Lung Adenocarcinoma Patients

The embryonic stem cell marker Oct4 is expressed in several human cancers and is positively correlated with a poor outcome in cancer patients. However, its physiological role in cancer progression remains poorly understood. Tumor cells block apoptosis to escape cell death so that they can proliferate indefinitely, leading to ineffective therapy for cancer patients. In this study, we investigated whether Oct4 regulates the apoptosis pathway and contributes to poor prognosis in patients with lung adenocarcinoma. Our results revealed that Oct4 expression is correlated with Stat1 expression in lung adenocarcinoma patients and Oct4 is directly bound to the Stat1 promoter to transactivate Stat1 in lung adenocarcinoma cells. Expression of the Stat1 downstream gene Mcl-1 increased in Oct4-overexpressing cancer cells, while Stat1 knockdown in Oct4-overexpressing cancer cells sensitized them to cisplatin-induced apoptosis. Furthermore, Oct4 promoted Stat1 expression and tumor growth, whereas silencing of Stat1 reduced Oct4-induced tumor growth in human lung tumor xenograft models. Taken together, we demonstrate that Oct4 is a pro-survival factor by inducing Stat1 expression and that the Oct4/Stat1/Mcl-1 axis may be a potential therapeutic target for lung adenocarcinoma.

Translational insights into stem cell preconditioning: From molecular mechanisms to preclinical applications

Cell-based therapy (CBT) is a revolutionary approach for curing a variety of degenerative diseases. Stem cell-based regenerative medicine is a novel strategy for treating tissue damages regarding stem cells unique properties such as differentiation potential, paracrine impacts, and self-renewal ability. However, the current cell-based treatments encounter considerable challenges to be translated into clinical practice, including low cell survival, migration, and differentiation rate of transplanted stem cells. The poor stem cell therapy outcomes mainly originate from the unfavorable condition of damaged tissues for transplanted stem cells. The promising method of preconditioning improves cell resistance against the host environment's stress by imposing certain conditions similar to the harsh microenvironment of the damaged tissues on the transplanted stem cells. Various pharmacological, biological, and physical inducers are able to establish preconditioning. In addition to their known pharmacological effects on tissues and cells, these preconditioning agents improve cell biological aspects such as cell survival, proliferation, differentiation, migration, immunomodulation, paracrine impacts, and angiogenesis. This review focuses on different protocols and inducers of preconditioning along with underlying molecular mechanisms of their effects on stem cell behavior. Moreover, preclinical applications of preconditioned stem cells in various damaged organs such as heart, lung, brain, bone, cartilage, liver, and kidney are discussed with prospects of their translation into the clinic.

MicroRNA‑8063 targets heterogeneous nuclear ribonucleoprotein AB to inhibit the self‑renewal of colorectal cancer stem cells via the Wnt/β‑catenin pathway

The presence of cancer stem cells (CSCs) is a major cause of therapeutic failure in a variety of cancer types, including colorectal cancer (CRC). However, the underlying mechanisms that regulate the self-renewal of colorectal cancer stem cells (CRCSCs) remain unclear. Our previous study utilized CRCSCs and their parent cells; through gene microarray screening and bioinformatics analysis, we hypothesized that microRNA (miR)-8063 may bind to, and regulate the expression of, heterogeneous nuclear ribonucleoprotein AB (hnRNPAB) to facilitate the regulation of CRCSC self-renewal. The aim of the present study was to confirm this conjecture through relevant experiments. The results indicated that compared with that in parent cells, miR-8063 expression was significantly downregulated in CRCSCs, while hnRNPAB expression was increased. Furthermore, hnRNPAB was identified as a direct target of miR-8063 using a dual-Luciferase assay. Overexpression of hnRNPAB promoted the acquisition of CSC characteristics in CRC cells (increased colony formation ability, enhanced tumorigenicity, and upregulated expression of CSC markers), as well as the upregulation of key proteins (Wnt3a, Wnt5a and β-catenin) in the Wnt/β-catenin signaling pathway. Similarly, after silencing miR-8063 in CRC cells, the characteristics of CSC were altered, and the expression of hnRNPAB protein was promoted. However, post overexpression of miR-8063 in CRCSCs, the self-renewal ability of CSCs was weakened with the downregulation of hnRNPAB protein, Wnt3a, Wnt5a and β-catenin. These results suggest that as a tumor suppressor, miR-8063 is involved in regulating the self-renewal of CRCSCs, where loss of miR-8063 expression weakens its inhibition on hnRNPAB, which leads to the activation of Wnt/β-catenin signaling to promote the self-renewal of CRCSCs.

A Pilot Study Investigating the Expression Levels of Pluripotency-Associated Genes in Rectal Swab Samples for Colorectal Polyp and Cancer Diagnosis and Prognosis

Change in gene expression is inevitable in cancer development. With more studies demonstrating the contributions of cancer stem cells (CSCs) in colorectal cancer (CRC) development, this study is aimed at investigating whether rectal swab specimen serves as a tool for detection of dysregulation of CSC or stem cell (SC) markers and at evaluating its potential as a new promising screening method for high-risk patients. Expression levels of 15 pluripotency-associated genes were assessed by quantitative PCR in 53 rectal swab specimens referred for endoscopic screening. Dysregulated genes and joint panels based on such genes were examined for their diagnostic potentials for both polyp and CRC. Out of 15 genes, Oct4, CD26, c-MYC, and CXCR4 showed significantly differential expression among normal, polyp, and CRC patients. A panel of Oct4 and CD26 showed an AUC value of 0.80 (p = 0.003) in identifying CRC patients from polyp/normal subjects, with sensitivity and specificity of 84.6% and 69.2%. A panel of c-MYC and CXCR4 achieved CRC/polyp identification with an AUC value of 0.79 (p = 0.002), with a sensitivity of 82.8% and specificity of 80.0%. The sensitivity for polyp and CRC was 80.0% and 85.7%, respectively. Further analysis showed that higher c-MYC and CXCR4 level was detected in normal subjects who developed polyps after 5-6 years, in comparison with subjects with no lesion developed, and the AUC of the c-MYC and CXCR4 panel increased to 0.88 (p < 0.001), with sensitivity and specificity of 84.4% and 92.3%, respectively, when these patients were included in the polyp group. This study suggests that the Oct4 and CD26 panel is a promising biomarker for distinguishing CRC from normal and polyp patients, whereas the c-MYC and CXCR4 panel may identify polyp and CRC from normal individuals.

Emerging Importance of Survivin in Stem Cells and Cancer: the Development of New Cancer Therapeutics

Survivin is one of the rare proteins that is differentially expressed in normal and cancer cells and is directly or indirectly involved in numerous pathways required for tumor maintenance. It is expressed in almost all cancers and its expression has been detected at early stages of cancer. These traits make survivin an exceptionally attractive target for cancer therapeutics. Even with these promising features to be an oncotherapeutic target, there has been limited success in the clinical trials targeting survivin. Only recently it has emerged that survivin was not being specifically targeted which could have resulted in the negative clinical outcome. Also, focus of research has now shifted from survivin expression in the overall heterogeneous tumor cell populations to survivin expression in cancer stem cells as these cells have proved to be the major drivers of tumors. Therefore, in this review we have analyzed the expression of survivin in normal and cancer cells with a particular focus on its expression in cancer stem cell compartment. We have discussed the major signaling pathways involved in regulation of survivin. We have explored the current development status of various types of interventions for inhibition of survivin. Furthermore, we have discussed the challenges involving the development of potent and specific survivin inhibitors for cancer therapeutics. Finally we have given insights for some of the promising future anticancer treatments.

Prognostic implication of SOX2 expression in small intestinal adenocarcinoma

The presence of KRAS mutation enhances the stem cell features of colorectal carcinoma cells containing mutant adenomatous polyposis coli (APC). However, their potential role in small intestinal adenocarcinoma remains elusive. Here, we aimed to investigate the clinical significance of cancer stem cell markers expression in the context of small intestinal adenocarcinoma with the KRAS genotype. SOX2, NANOG, and OCT4 expression were assessed by immunohistochemistry and digital image analysis, and their potential association with KRAS was further examined in 185 Korean patients with small intestinal adenocarcinomas, which were collected from 22 institutions in South Korea. Positive expression of SOX2, NANOG, and OCT4 was detected in 65 (35.1%), 94 (50.8%), and 82 (44.3%) of patients, respectively. Patients with high SOX2 (SOX2+) expression displayed worse overall survival compared to those with low SOX2 (SOX2-) expression (P < 0.001). Patients with SOX2+/mutant KRAS (KRAS^MT) (11.1 months) had significantly shorter overall survival than those with SOX2-/KRAS^WT (53.6 months) (P < 0.001). In multivariate analysis, SOX2+, distal location, high pT and pN categories, microsatellite stable, and absence of predisposing diseases were independent prognostic factors for worse overall survival. These results suggest that SOX2 expression has the potential to predict clinical outcomes in patients with small intestinal adenocarcinomas.

Curcumol increases the sensitivity of colon cancer to 5-FU by regulating Wnt/β-catenin signaling

Background

5-fluorouracil (5-FU) resistance is the leading cause of treatment failure in colon cancer. Combination therapy is an effective strategy to inhibit cancer cells and prevent drug resistance. Therefore, we studied the antitumor effect of curcumol alone or combined with 5-FU on human colon cancer drug-resistant cells.

Methods

The 5-FU resistant HCT116 cell line (HCT116/5-FU) was established by repeated exposure to gradually increasing concentrations of 5-FU; Cell viability was measured by cell counting kit-8 (CCK-8); apoptosis rate of HCT116 cells was detected using Annexin V-fluorescein isothiocyanate (FITC) assay kit; cell proliferation and invasion were detected using colony formation assays, wound healing assay and transwell invasion assays; activity of transplanted tumor in vivo in specific pathogen free (SPF) BALB/c nude mice (6 weeks old, male) was monitored by bioluminescence imaging, immunohistochemistry and western blot analysis.

Results

Our study showed the potent antitumor effect of curcumol by induction of apoptosis, inhibition of proliferation, invasion, migration, and improvement of the therapeutic efficacy of 5-FU toward human colon cancer HCT116 cells. From our results, curcumol could chemosensitize 5-FU-resistant HCT116 cells. The combination of curcumol and 5-FU exerted a synergistic inhibitory effect on the induction of apoptosis. Also, this combination inhibited the proliferation, invasion, and migration of both chemo-resistant and sensitive cells. Curcumol treatment decreased multidrug resistance-associated protein 2 (MRP-2), P-glycoprotein (P-gp), survivin, and β-catenin expression, which correlated with multidrug resistance (MDR) and the target genes of Wnt/β-catenin. It significantly increased the p-β-catenin level and Bad/Bcl-2 ratio in HCT116/5-FU cells compared with 5-FU treatment. In vivo, curcumol significantly inhibited the growth of transplanted tumors and the expression of Ki-67, proliferating cell nuclear antigen (PCNA), and vascular endothelial growth factor (VEGF) in colon cancer cells.

Conclusions

Curcumol as a potential chemotherapeutic agent combined with 5-FU can overcome colon cancer resistance.

Targeting stemness of cancer stem cells to fight colorectal cancers

Cancer initiating/ stem cells (CSCs) undergo self-renewal and differentiation that contributes to tumor initiation, recurrence and metastasis in colorectal cancer (CRC). Targeting of colorectal cancer stem cells (CCSCs) holds significant promise in eradicating cancer cells and ultimately curing patients with cancer. In this review, we will introduce the current progress of CCSC studies, including the specific surface markers of CCSCs, the intrinsic signaling pathways that regulate the stemness and differentiation characteristics of CCSCs, and the tumor organoid model for CCSC research. We will focus on how these studies will lead to the progress in targeting specific surface markers or signaling pathways on CCSCs by monoclonal antibodies, or by natural or synthetic compounds, or by immunotherapy. As CSCs are highly heterogeneous and plastic, we suggest that combinatory approaches that target the stemness network may represent an important strategy for eradicating cancers.

Farnesyl dimethyl chromanol targets colon cancer stem cells and prevents colorectal cancer metastasis

The activation and growth of tumour-initiating cells with stem-like properties in distant organs characterize colorectal cancer (CRC) growth and metastasis. Thus, inhibition of colon cancer stem cell (CCSC) growth holds promise for CRC growth and metastasis prevention. We and others have shown that farnesyl dimethyl chromanol (FDMC) inhibits cancer cell growth and induces apoptosis in vitro and in vivo. We provide the first demonstration that FDMC inhibits CCSC viability, survival, self-renewal (spheroid formation), pluripotent transcription factors (Nanog, Oct4, and Sox2) expression, organoids formation, and Wnt/β-catenin signalling, as evidenced by comparisons with vehicle-treated controls. In addition, FDMC inhibits CCSC migration, invasion, inflammation (NF-kB), angiogenesis (vascular endothelial growth factor, VEGF), and metastasis (MMP9), which are critical tumour metastasis processes. Moreover, FDMC induced apoptosis (TUNEL, Annexin V, cleaved caspase 3, and cleaved PARP) in CCSCs and CCSC-derived spheroids and organoids. Finally, in an orthotopic (cecum-injected CCSCs) xenograft metastasis model, we show that FDMC significantly retards CCSC-derived tumour growth (Ki-67); inhibits inflammation (NF-kB), angiogenesis (VEGF and CD31), and β-catenin signalling; and induces apoptosis (cleaved PARP) in tumour tissues and inhibits liver metastasis. In summary, our results demonstrate that FDMC inhibits the CCSC metastatic phenotype and thereby supports investigating its ability to prevent CRC metastases.

Hsa-miR-3658 down-regulates OCT4 gene expression followed by suppressing SW480 cell proliferation and migration

The pluripotency factor, OCT4 gene is a stemness marker that is involved in the tumorigenicity of different cancer types and knowing about molecular mechanisms of its regulation is crucially important. To date, a few microRNAs (miRNAs) are known to be regulators of OCT4 gene expression. Looking for the novel miRNAs which are capable of regulating OCT4 gene expression, our bioinformatics analysis introduced hsa-miR-3658 (miR-3658) as a bona fide candidate. Then, RT-qPCR results indicated that miR-3658 expression is decreased in colorectal cancer (CRC) tumor tissues, compared with normal pairs. Furthermore, RT-qPCR and western blot analysis showed that the OCT4 gene has been down-regulated following the miR-3658 overexpression. Consistently, dual-luciferase assay supported the direct interaction of miR-3658 with the 3'-UTR sequence of OCT4 gene. Unlike in HCT116 cells, overexpression of miR-3658 in SW480 cells brought about growth inhibition, cell cycle arrest and reduced cell migration, detected by flow cytometry, and scratch test assay. Overall, these findings demonstrated that miR-3658 as a tumor suppressor miRNA exerts its effect against OCT4 gene expression, and it has the potential of being used as a prognostic marker and therapeutic target against colorectal cancer.

Is There Such a Thing as a Genuine Cancer Stem Cell Marker? Perspectives from the Gut, the Brain and the Dental Pulp

The conversion of healthy stem cells into cancer stem cells (CSCs) is believed to underlie tumor relapse after surgical removal and fuel tumor growth and invasiveness. CSCs often arise from the malignant transformation of resident multipotent stem cells, which are present in most human tissues. Some organs, such as the gut and the brain, can give rise to very aggressive types of cancers, contrary to the dental pulp, which is a tissue with a very remarkable resistance to oncogenesis. In this review, we focus on the similarities and differences between gut, brain and dental pulp stem cells and their related CSCs, placing a particular emphasis on both their shared and distinctive cell markers, including the expression of pluripotency core factors. We discuss some of their similarities and differences with regard to oncogenic signaling, telomerase activity and their intrinsic propensity to degenerate to CSCs. We also explore the characteristics of the events and mutations leading to malignant transformation in each case. Importantly, healthy dental pulp stem cells (DPSCs) share a great deal of features with many of the so far reported CSC phenotypes found in malignant neoplasms. However, there exist literally no reports about the contribution of DPSCs to malignant tumors. This raises the question about the particularities of the dental pulp and what specific barriers to malignancy might be present in the case of this tissue. These notable differences warrant further research to decipher the singular properties of DPSCs that make them resistant to transformation, and to unravel new therapeutic targets to treat deadly tumors.

Intracellular and extracellular S100A9 trigger epithelial-mesenchymal transition and promote the invasive phenotype of pituitary adenoma through activation of AKT1

Pituitary adenoma (PA) is mostly benign intracranial tumor, but it also displays invasive growth characteristics and provokes challenging clinical conditions. S100A9 protein enhances tumor progression. In this study, we firstly demonstrated that both intracellular and extracellular S100A9 promoted the expression of Vimentin and Intercellular cell adhesion molecule-1 (ICAM-1), coupled with reduced E-cadherin in PA. As a result, PA acquired the phenotype of Epithelial-Mesenchymal Transition (EMT), leading to proliferation, cell cycle progression, migration and invasion. In addition, we indicated S100A9-induced EMT was mediated by activation of AKT1. Furthermore, immunohistochemistry showed that S100A9 expression was higher in invasive PA than that in non-invasive PA. These data extended our understanding for the effects of S100A9 on PA invasion and contributed to further development of a promising therapeutic target for invasive PA.

Prognostic value of octamer binding transcription factor 4 for patients with solid tumors: A meta-analysis

BACKGROUND

Octamer binding transcription factor 4 (Oct4) is critically important in the development and progression of cancer, and is considered a potential biomarker for tumor prognosis. However, the prognostic value of Oct4 in patients with solid tumors remains elusive. Herein, we conducted a meta-analysis to assess the prognostic value of Oct4 in patients with solid tumors.

METHODS

We conducted a literature search on PubMed, Embase, and Web of Science databases to retrieve comprehensive and eligible studies published until December 2019. The study was conducted per the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. The pooled hazard ratios (HRs) with 95% confidence intervals (CIs) of overall survival (OS) and disease-free survival (DFS)/recurrence-free survival (RFS)/progress-free survival (PFS) were used to evaluate the prognostic value of Oct4 in patients with solid tumors via either random or fixed-effects models.

RESULTS

In total, 36 studies with 5198 patients were included in the meta-analysis. Notably, elevated Oct4 expression was associated with worse OS (pooled HR: 2.02, 95% CI: 1.55-2.62, P < .001) and DFS/RFS/PFS (pooled HR: 2.34, 95% CI: 1.88-2.92, P < .001).

CONCLUSION

This work demonstrated that patients with solid tumors show high expression of Oct4 which is linked to worse prognosis in patients with solid tumors including hepatocellular carcinoma (OS, DFS/RFS/PFS), esophageal squamous cell carcinoma (OS), gastric cancer (OS), cervical cancer (OS, DFS/RFS/PFS), and colorectal cancer (OS, DFS/RFS/PFS), this implicated Oct4 as a potential biomarker to predict the prognosis of tumors.

Chemotherapy and chemo-resistance in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is closely associated with Epstein-Barr virus (EBV) and occurs frequently in the south of China and Southeast Asian countries. Concurrent chemo-radiotherapy is one of the main treatments for NPC. Although, the combined treatment of chemo-radiotherapy produces a satisfying survival rate, the chemo-resistance arises as a big obstacle in curing recurrent NPC patients. The acquirement of chemo-resistance is usually along with a poor prognosis. So far, the mechanism of chemo-resistance in NPC has not been fully elucidated and there have not been a comprehensive review on this issue. Thus, it is of great significance to summarize the mechanisms involved in NPC chemo-resistance. In this review, the importance and limitations of chemotherapy and the mechanisms of chemo-resistances in NPC were discussed.

Prognostic value of stem cell markers in esophageal and esophagogastric junction cancer: a meta-analysis

Background: Esophageal cancer is an aggressive tumor, with poor prognosis and low survival rates. Although diagnosis and treatment have improved considerably, more efficient prognostic factors are urgently needed to prevent postoperative recurrence and metastasis. Cancer stem cells are key players in tumor progression and several studies have investigated the association between the expression of stemness genes and clinical outcome. However, the prognostic value of stemness markers in esophageal cancer remains controversial. We identified six factors involved in angiogenesis, anti-apoptosis and self-renewal that have been associated to poor prognosis in other types of cancer. We conducted a review of the literature and a meta-analysis to assess their potential prognostic role in this malignancy.

Material and Methods: The database of PMC, PubMed, Web of Science, Embase and The Cochrane Library were searched to investigate the association between CD34, CD133, Nucleostemin, OCT-4, NANOG and CD90, and the survival of patients affected by esophageal squamous cell carcinoma or esophageal adenocarcinoma. Among the 615 eligible studies, a total of 19 articles (including 1586 patients) met the inclusion criteria for the meta-analysis, and the pooled hazard ratio and 95% confidence intervals were calculated.

Results: Data showed that high expression of CD34 (HR 2.10; 95%CI 1.41-3.14; I²=56%; p=0.0003), CD133 (HR 1.91; 95%CI 1.15-3.19; I²=55%; p=0.01) and Nucleostemin (HR 2.97; 95%CI 1.11-7.98; I²=0%; p=0.03) were associated with poor prognosis in patients affected by esophageal cancer. The expression of NANOG and OCT-4 showed no significant association with survival of patients, whereas no study involving CD90 was included in this meta-analysis. Conclusion: CD34, CD133 and Nucleostemin might represent useful prognostic markers in patients affected by esophageal cancer.

Role of Oct4-Sox2 complex decoy oligodeoxynucleotides strategy on reverse epithelial to mesenchymal transition (EMT) induction in HT29-ShE encompassing enriched cancer stem-like cells

Cancer stem cells are commonly tolerant toward chemotherapy and radiotherapy. Oct4 and Sox2 transcription factors are shown to be overexpressed in various cancers. At the current research, inhibition of Oct4 and Sox2 transcription factors was performed through application of decoy oligodeoxynucleotides (ODNs) strategy via repressing stemness properties in HT29-ShE cells encompassing enriched cancer stem-like cells. Designed Oct4-Sox2 complex decoy ODNs were transfected into HT29-ShE cells with Lipofectamine reagent. At the next step, ODNs efficiency transfection and subcellular localization were determined via flow cytometry and fluorescence microscopy, respectively. Further investigations such as cell proliferation and apoptosis analysis, colonosphere formation, invasion and migration, and real-time PCR assays were also carried out. Obtained results shed light on the fact that the designed complex decoys were effectively transfected into HT29-ShE cells, and they were found to be localized in subcellular compartments. Oct4-Sox2 decoy ODNs led to decreased cell viability, arresting the cell cycle in G0/G1 phases, increasing apoptosis, inhibition of migration/invasion and colonosphere formation ability of HT29-ShE cells in comparison with control and scramble groups. Furthermore, Oct4-Sox2 complex decoy could modulate the MET process via alteration of mRNA expression of downstream genes. It could be concluded that application of Oct4-Sox2 transcription factor decoy strategy in cells with stemness potential could lead to inhibiting the cell growth and triggering differentiation. Therefore, this technique could be applied along with usual remedies (chemotherapy and radiotherapy) as high potential method for treating cancer.

Cancer stem cell subpopulations in primary colon adenocarcinoma

Aims

The cancer stem cell concept proposes that tumor growth and recurrence is driven by a small population of cancer stem cells (CSCs). In this study we investigated the expression of induced-pluripotent stem cell (iPSC) markers and their localization in primary low-grade adenocarcinoma (LGCA) and high-grade adenocarcinoma (HGCA) and their patient-matched normal colon samples.

Materials and methods

Transcription and translation of iPSC markers OCT4, SOX2, NANOG, KLF4 and c-MYC were investigated using immunohistochemical (IHC) staining, RT-qPCR and in-situ hybridization (ISH).

Results

All five iPSC markers were detected at the transcriptional and translational levels. Protein abundance was found to be correlated with tumor grade. Based on their protein expression within the tumors, two sub-populations of cells were identified: a NANOG⁺/OCT4^- epithelial subpopulation and an OCT4⁺/NANOG^- stromal subpopulation. All cases were accurately graded based on four pieces of iPSC marker-related data.

Conclusions

This study suggests the presence of two putative sub-populations of CSCs: a NANOG⁺/OCT4^- epithelial subpopulation and an OCT4⁺/NANOG^- stromal subpopulation. Normal colon, LGCA and HGCA could be accurately distinguished from one another using iPSC marker expression. Once validated, novel combinations of iPSC markers may provide diagnostic and prognostic value to help guide patient management.

OCT4B1 Promoted EMT and Regulated the Self-Renewal of CSCs in CRC: Effects Associated with the Balance of miR-8064/PLK1

Cancer stem cells (CSCs) are the main cause of tumor generation, recurrence, metastasis, and therapy failure in various malignancies including colorectal cancer (CRC). Accumulating evidence suggests that tumor cells can acquire CSC characteristics through the epithelial-mesenchymal transition (EMT) process. However, the molecular mechanism of CSCs remains unclear. OCT4B1 is a transcript of OCT4, which is initially expressed in embryonic stem and carcinoma cells, and is involved in the regulation and maintenance of an undifferentiated state of stem cells. In this study, three-dimensional (3D) microspheres were confirmed as CRC stem cells. Compared with that of parental cells, their self-renewal ability was significantly increased, and OCT4B1 expression was increased and promoted the EMT process. The knockdown of OCT4B1 decreased the self-renewal of CSCs and reversed EMT. Moreover, OCT4B1 induced the expression of Polo-like kinase 1 (PLK1), which is a key regulator of EMT in tumor cells. Further examination showed that OCT4B1 regulated the miR-8064/PLK1 balance to exert its function. Taken together, our data suggest that OCT4B1 may be involved in regulating the self-renewal of colorectal CSCs through EMT, which is at least partially due to the miR-8064/PLK1 balance. This study indicates that OCT4B1 is a potential therapeutic target for CRC by targeting CSCs.

The pluripotency network in colorectal cancer pathogenesis and prognosis: an update

Stemness characteristics are defining properties of cancer initiating cells and are associated with the ability to metastasize and survive in hostile environments. Establishment of the stem cell network depends on the action of a set of core transcription factors that work in concert with other ancillary proteins that are also important during embryonic development. New data consolidate the role of core pluripotency transcription factors OCT4, SOX2 and NANOG as adverse prognostic factors in colorectal cancer. mRNA-binding proteins LIN28 and Musashi, that are associated with stemness, and epigenetic modifiers such as de-acetylase SIRT1 may also have prognostic value in colorectal cancer. This paper provides an update of the stem cell factors in the pathogenesis and prognosis of colorectal cancer.

TUFT1 Promotes Triple Negative Breast Cancer Metastasis, Stemness, and Chemoresistance by Up-Regulating the Rac1/β-Catenin Pathway

Objectives: Triple negative breast cancer (TNBC) is a subtype of breast cancer with stronger invasion and metastasis, but its specific mechanism of action is still unclear. Tuft1 plays an important regulatory role in the survival of breast cancer cells; however, its role in regulating TNBC metastatic potential has not been well-characterized. Our aim was therefore to systematically study the mechanism of TUFT1 in the metastasis, stemness, and chemoresistance of TNBC and provide new predictors and targets for BC treatment. Methods: We used western blotting and IHC to measure TUFT1and Rac1-GTP expression levels in both human BC samples and cell lines. A combination of shRNA, migration/invasion assays, sphere formation assay, apoptosis assays, nude mouse xenograft tumor model, and GTP activity assays was used for further mechanistic studies. Results: We demonstrated that silencing TUFT1 in TNBC cells significantly inhibited cell metastasis and stemness in vitro. A nude mouse xenograft tumor model revealed that TUFT1 knockdown greatly decreased spontaneous lung metastasis of TNBC tumors. Mechanism studies showed that TUFT1 promoted tumor cell metastasis and stemness by up-regulating the Rac1/β-catenin pathway. Moreover, mechanistic studies indicated that the lack of TUFT1 expression in TNBC cells conferred more sensitive to chemotherapy and increased cell apoptosis via down-regulating the Rac1/β-catenin signaling pathway. Further, TUFT1 expression positively correlated with Rac1-GTP in TNBC samples, and co-expression of TUFT1 and Rac1-GTP predicted poor prognosis in TNBC patients who treated with chemotherapy. Conclusion: Our findings suggest that TUFT1/Rac1/β-catenin pathway may provide a potential target for more effective treatment of TNBC.

Cancer stem cells: A review from origin to therapeutic implications

Cancer stem cells (CSCs), also known as tumor-initiating cells (TICs), are elucidated as cells that can perpetuate themselves via autorestoration. These cells are highly resistant to current therapeutic approaches and are the main reason for cancer recurrence. Radiotherapy has made a lot of contributions to cancer treatment. However, despite continuous achievements, therapy resistance and tumor recurrence are still prevalent in most patients. This resistance might be partly related to the existence of CSCs. In the present study, recent advances in the investigation of different biological properties of CSCs, such as their origin, markers, characteristics, and targeting have been reviewed. We have also focused our discussion on radioresistance and adaptive responses of CSCs and their related extrinsic and intrinsic influential factors. In summary, we suggest CSCs as the prime therapeutic target for cancer treatment.

Effect and Mechanism of Survivin on Hypoxia-Induced Multidrug Resistance of Human Laryngeal Carcinoma Cells

This study aimed at clarifying the mechanism and role of survivin in hypoxia-induced multidrug resistance (MDR) of laryngeal carcinoma cells. Human laryngeal cancer cells were incubated under hypoxia or normoxia. The expression of survivin was silenced by performing RNA interference. Additionally, by Western blot and real-time quantitative RT-PCR, survivin expression was detected. The sensitivity of human laryngeal carcinoma cells to multiple drugs was measured by CCK-8 assay. Meanwhile, the apoptosis of cells induced by cisplatin or paclitaxel was assessed by Annexin-V/propidium iodide staining analysis. Under hypoxic conditions, the upregulation of survivin was abolished by RNA interference. Then, CCK-8 analysis demonstrated that the sensitivity to multiple agents of laryngeal carcinoma cells could be increased by inhibiting survivin expression (P < 0.05). Moreover, Annexin-V/propidium iodide staining analysis revealed that decreased expression of survivin could evidently increase the apoptosis rate of laryngeal carcinoma cells that were induced by cisplatin or paclitaxel evidently (P < 0.05). Our data suggests that hypoxia-elicited survivin may exert a pivotal role in regulating hypoxia-induced MDR of laryngeal cancer cells by preventing the apoptosis of cells induced by chemotherapeutic drug. Thus, blocking survivin expression in human laryngeal carcinoma cells may provide an avenue for gene therapy.

TIAM1 promotes chemoresistance and tumor invasiveness in colorectal cancer

Accumulating evidence suggests that cancer cells with stem cell-like features have higher resistance to chemotherapeutic agents. Herein, we identified T-lymphoma invasion and metastasis-inducing protein-1 (TIAM1) as one of the Wnt-signaling associated genes which drives self-renewal and its expression is upregulated by cancer associated fibroblasts (CAFs). TIAM1 expression was assessed in resected colorectal cancer (CRC) tissues from 300 patients who did or did not respond to chemotherapy. siRNA and CRISPR/Cas9 was used to examine whether the inhibition of TIAM1 affects chemosensitivity of CRC. We demonstrate that stemness through Wnt signaling regulates chemosensitivity and this phenomenon occurs exclusively in cancer stem cells. Subsequently, we established patient-derived CAFs and tested whether the drug sensitivity of CRC cell lines is altered with CAF-derived conditioned medium. High-TIAM1 expression correlated significantly with poor prognosis of CRC patients, and was overexpressed in patients who did not respond to chemotherapy. We demonstrated that the inhibition of TIAM1 enhanced sensitivity to chemotherapeutic drugs and reduced tumor invasiveness in a series of experiments in vitro. Moreover, CAF-derived conditioned media increased stemness and chemoresistance in CRC cell lines through TIAM1 overexpression. In addition, we validated TIAM1 associated drug sensitivity using a xenograft model. We have demonstrated that TIAM1 is overexpressed in CRC tumors from patients who did not respond to chemotherapeutic drugs and levels of TIAM1 expression served as an independent prognostic factor. Mechanistically, CAFs enhanced CRC chemoresistance through TIAM1 overexpression. Collectively, these results suggest that TIAM1 regulates chemosensitivity in tumors and stroma and thus may be an attractive therapeutic target.

Sox2 is associated with cancer stem-like properties in colorectal cancer

Sox2 is known as the undifferentiated cell marker. Recent studies have shown that Sox2 may also be involved in the maintenance of cancer stem cells (CSCs) in skin and bladder cancers. In this study, we aimed to clarify the role of Sox2 in colorectal CSCs. Sox2 expression was measured in colon cancer cells and colorectal clinical samples by qRT-PCR and western blot analysis. To visualize the active Sox2 mRNA production, we generated a Sox2 promoter-dependent DsRed fluorescence emission system. Colon cancer cell lines and colorectal tumor tissues generally expressed the Sox2 protein. Knockdown of Sox2 by siRNA led to increased proliferative activity in Caco2 cells. Kaplan-Meier survival curves showed that the group with high Sox2 mRNA expression had a worse prognosis for relapse-free survival (RFS) than the low expression group (P = 0.045, median follow-up 60.0 months). Time-lapse image analysis revealed that most DsRed⁺ cells exhibited typical asymmetric cell division and had higher CSC marker expressions. The DsRed⁺ cells exhibited chemoresistance and they grew slower in vitro, yet they established rather larger tumors in vivo. Our data suggest that Sox2 may be a potential biomarker for colorectal CSCs.

Trifluoperazine prevents FOXO1 nuclear excretion and reverses doxorubicin-resistance in the SHG44/DOX drug-resistant glioma cell line

As a tumor suppressor, Forkhead box O1 (FOXO1) is located in the nucleus where it regulates gene expression and inhibits tumor progression. However, the antitumor effects of FOXO1 are attenuated in several tumors due to its translocation from the nucleus to the cytoplasm. Trifluoperazine (TFP) is able to reverse tumor drug resistance by inhibiting multidrug resistance (MDR), however, the detailed molecular mechanisms by which this occurs remain to be fully elucidated. In the present study, the doxorubicin (DOX)‑resistant SHG44/DOX glioma cell line was established. The results showed that TFP promoted DOX‑induced cytotoxicity, cell cycle arrest and early apoptosis using a Cell Counting Kit‑8 and flow cytometry. In vivo experiments also demonstrated that DOX combined with TFP reduced tumor volumes and proliferation indices, and led to higher protein levels of FOXO1. In addition, TFP inhibited the nuclear exclusion of FOXO1, contributing toward the downregulation of MDR genes and an increase in intracellular DOX concentrations by reverse transcription‑quantitative polymerase chain reaction, western blot analysis, immunofluorescence and spectrophotometer analysis. Therefore, TFP may inhibit DOX resistance by stimulating FOXO1 nuclear translocation and suppressing MDF genes in SHG44/DOX cells, contributing to promising clinical prospects for tumor chemotherapy.

Melatonin and 5-fluorouracil co-suppress colon cancer stem cells by regulating cellular prion protein-Oct4 axis

Melatonin suppresses tumor development. However, the exact relationship between melatonin and cancer stem cells (CSCs) is poorly understood. This study found that melatonin inhibits colon CSCs by regulating the PrP^C -Oct4 axis. In specimens from patients with colorectal cancer, the expressions of cellular prion protein (PrP^C ) and Oct4 were significantly correlated with metastasis and tumor stages. Co-treatment with 5-fluorouracil (5-FU) and melatonin inhibited the stem cell markers Oct4, Nanog, Sox2, and ALDH1A1 by downregulating PrP^C . In this way, tumor growth, proliferation, and tumor-mediated angiogenesis were suppressed. In colorectal CSCs, PRNP overexpression protects Oct4 against inhibition by 5-FU and melatonin. In contrast, Nanog, Sox2, and ALDH1A1 have no such protection. These results indicate that PrP^C directly regulates Oct4, whereas it indirectly regulates Nanog, Sox2, and ALDH1A1. Taken together, our findings suggest that co-treatment with anticancer drug and melatonin is a potential therapy for colorectal cancer. Furthermore, PrP^C maintains cancer stemness during tumor progression. Therefore, targeting the PrP^C -Oct4 axis may prove instrumental in colorectal cancer therapy.

An ABCG2 non-substrate anticancer agent FL118 targets drug-resistant cancer stem-like cells and overcomes treatment resistance of human pancreatic cancer

Background

Pancreatic cancer is a deadly disease with a very low 5-year patient survival rate of 6–8%. The major challenges of eliminating pancreatic cancer are treatment resistance and stromal barriers to optimal drug access within the tumor. Therefore, effective molecular targeting drugs with high intra-tumor access and retention are urgently needed for managing this devastating disease in the clinic.

Methods

This study has used the following in vitro and in vivo techniques for the investigation of exceptional anticancer drug FL118’s efficacy in treatment of resistant pancreatic cancer: cell culture; immunoblotting analysis to test protein expression; DNA sub-G1 flow cytometry analyses to test cell death; MTT assay to test cell viability; pancreatic cancer stem cell assays (fluorescence microscopy tracing; matrigel assay; CD44-positive cell colony formation assay); human luciferase-labeled pancreatic tumor orthotopic animal model in vivo imaging; pancreatic cancer patient-derived xenograft (PDX) animal models; and toxicology studies with immune-competent BALB/cj mice and beagle dogs.

Results

Our studies found that FL118 alone preferentially killed cisplatin-resistant cancer cells, while a combination of FL118 with cisplatin synergistically killed resistant pancreatic cancer cells and reduced spheroid formation of treatment-resistant pancreatic cancer stem-like cells. Furthermore, using in vivo-imaging, we found that FL118 in combination with cisplatin strongly inhibited both drug-resistant pancreatic xenograft tumor growth and metastasis. In PDX model, we demonstrated that FL118 alone effectively eliminated PDX tumors, while FL118 in combination with gemcitabine eliminated PDX tumors that showed relative resistance (less sensitivity) to treatment with FL118. These FL118 efficacy results are consistent with our molecular-targeting data showing that FL118 inhibited the expression of multiple antiapoptotic proteins (survivin, Mcl-1, XIAP, cIAP2) and ERCC6, a critical regulator of DNA repair, in treatment-resistant pancreatic stem-like cancer cells. Furthermore, FL118 toxicity studies in BALB/cj mice and beagle dogs indicated that FL118 exhibits favorable hematopoietic and biochemical toxicities.

Conclusion

Together, our studies suggest that FL118 is a promising anticancer drug for further clinical development to effectively treat drug-resistant pancreatic cancer alone or in combination with other pancreatic cancer chemotherapeutic drugs.

Regulation of tNOX expression through the ROS-p53-POU3F2 axis contributes to cellular responses against oxaliplatin in human colon cancer cells

BACKGROUND

Oxaliplatin belongs to the platinum-based drug family and has shown promise in treating cancer by binding to DNA to induce cytotoxicity. However, individual patients show diverse therapeutic responses toward oxaliplatin due to yet-unknown underlying mechanisms. We recently established that oxaliplatin also exert its anti-cancer activity in gastric cancer cell lines by targeting tumor-associated NADH oxidase (tNOX), attenuate NAD⁺ generation and reduce NAD⁺-dependent sirtuin 1 (SIRT1) deacetylase activity, which in turn enhances p53 acetylation and apoptosis.

METHODS

In this study, differential cellular outcomes in response to oxaliplatin exposure of p53-wild-type versus p53-null HCT116 human colon cancer cells were examined. Cell growth profile was determined by cell impedance measurements and apoptosis was analyzed by flow cytometry. The engagement between oxaliplatin and tNOX protein was studied by cellular thermal shift assay. Furthermore, western blot analysis revealed that p53 was important in regulating tNOX expression in these cell lines.

RESULTS

In p53-wild-type cells, we found that oxaliplatin inhibited cell growth by inducing apoptosis and concurrently down-regulating tNOX at both the transcriptional and translational levels. In p53-null cells, in contrast, oxaliplatin moderately up-regulated tNOX expression and yielded no apoptosis and much less cytotoxicity. Further experiments revealed that in p53-wild-type cells, oxaliplatin enhanced ROS generation and p53 transcriptional activation, leading to down-regulation of the transcriptional factor, POU3F2, which enhances the expression of tNOX. Moreover, the addition of a ROS scavenger reversed the p53 activation, POU3F2 down-regulation, and apoptosis induced by oxaliplatin in p53-wild-type cells. In the p53-null line, on the other hand, oxaliplatin treatment triggered less ROS generation and no p53 protein, such that POU3F2 and tNOX were not down-regulated and oxaliplatin-mediated cytotoxicity was attenuated.

CONCLUSION

Our results show that oxaliplatin mediates differential cellular responses in colon cancer cells depending on their p53 status, and demonstrate that the ROS-p53 axis is important for regulating POU3F2 and its downstream target, tNOX. Notably, the depletion of tNOX sensitizes p53-null cells to both spontaneous and oxaliplatin-induced apoptosis. Our work thus clearly shows a scenario in which targeting of tNOX may be a potential strategy for cancer therapy in a p53-inactivated system.

The Dual Role of Bone Morphogenetic Proteins in Cancer

Bone morphogenetic proteins (BMPs) are a diverse class of molecules with over 20 growth factor proteins that belong to the transforming growth factor-β (TGF-β) family and are highly associated with bone formation and disease development. Aberrant expression of various BMPs has been reported in several cancer tissues. Biological function studies have elicited the dual role of BMPs in both cancer development and suppression. Furthermore, a variety of BMP antagonists, ligands, and receptors have been shown to reduce or enhance tumorigenesis and metastasis. Knockout mouse models of BMP signaling components have also revealed that the suppression of BMP signaling impairs cancer metastasis. Herein, we highlight the basic clinical background and involvement of BMPs in modulating cancer progression and their dynamic interactions (e.g., with microRNAs) in the tumor microenvironment in addition to their mutations and roles in chemoprevention. We also suggest that BMPs should be considered a powerful putative therapeutic target in tumorigenesis and bone metastasis.

KIAA0247 suppresses the proliferation, angiogenesis and promote apoptosis of human glioma through inactivation of the AKT and Stat3 signaling pathway

Gliomas are the most common and aggressive type of primary adult brain tumors. Although KIAA0247 previously is a speculated target of the tumor suppressor gene, little is known about the association between KIAA0247 and glioma. In this study, we clearly demonstrate that KIAA0247 expression is decreased in glioma and was negatively correlated with the histologic grade. Overexpression of KIAA0247 in glioma cells inhibits proliferation, angiogenesis and promoted apoptosis of human glioma cells in vitro. In contrast, knockdown of KIAA0247 increases the proliferation, angiogenesis and decreases apoptosis of these cells. In a tumor xenograft model, overexpression of KIAA0247 suppresses tumor growth of glioma cells in vivo, while KIAA0247 knockdown promotes the tumor growth. Mechanistically, overexpression of KIAA0247 is able to inhibit phosphorylation of AKT and Stat3 in glioma cells, resulting in inactivation of the AKT and Stat3 signaling pathways, this ultimately decreases the expression of PCNA, CyclinD1, Bcl2 and VEGF. Collectively, these data indicate that KIAA0247 may work as a tumor suppressor gene in glioma and a promising therapeutic target for gliomas.

Dishevelled1-3 contribute to multidrug resistance in colorectal cancer via activating Wnt/β-catenin signaling

Multidrug resistance is a great obstacle in successful chemotherapy of colorectal cancer. However, the molecular mechanism underlying multidrug resistance is not fully understood. Dishevelled, a pivot in Wnt signaling, has been linked to cancer progression, while its role in chemoresistance remains unclear. Here, we found that Dishevelled1-3 was over-expressed in multidrug-resistant colorectal cancer cells (HCT-8/VCR) compared to their parental cells. Silencing Dishevelled1-3 resensitized HCT-8/VCR cells to multiple drugs including vincristine, 5-fluorouracil and oxaliplatin. Moreover, Dishevelled1-3 increased the protein levels of multidrug resistance protein 1 (P-gp/MDR1), multidrug resistance-associated protein 2 (MRP2), and breast cancer resistance protein (BCRP), Survivin and Bcl-2 which are correlated with multidrug resistance. shβ-catenin abolished Dishevelled-mediated these protein expressions. Unexpectedly, none of Dishevelled1-3 controlled β-catenin accumulation and nuclear translocation. Furthermore, the nuclear translocations of Dishevelled1-3 were promoted in HCT-8/VCR cells compared to HCT-8. Dishevelled1-3 bound to β-catenin in nucleus, and promoted nuclear complex formation and transcription activity of β-catenin/TCF. Taken together, Dishevelled1-3 contributed to multidrug resistance in colorectal cancer via activating Wnt/β-catenin signaling and inducing the expressions of P-gp, MRP2, BCRP, Survivin and Bcl-2, independently of β-catenin accumulation and nuclear translocation. Silencing Dishevelled1-3 resensitized multidrug-resistant colorectal cancer cells, providing a novel therapeutic target for successful chemotherapy of colorectal cancer.

Esophageal adenocarcinoma microenvironment: Peritumoral adipose tissue effects associated with chemoresistance

Peritumoral microenvironment affects cancer development and chemoresistance, and visceral adipose tissue may play a critical role. We aimed to identify depot‐specific adipose characteristics associated with carcinogenesis and resistance to neoadjuvant therapy in esophageal adenocarcinoma (EAC). We analyzed: (i) the peritumoral adipose tissue of rats following the induction of esophageal carcinogenesis; (ii) the peritumoral and distal (omental) adipose tissue of patients affected by EAC; (iii) adipose‐derived stem cells (ADSC) isolated from healthy patients and treated with conditioned medium (CM), collected from tumoral and adipose tissue of patients with EAC. In peritumoral adipose tissue of rats, CD34, CD31 and vascular endothelial growth factor (VEGF) expression increased progressively during EAC development. In patients with EAC, expression of CD34, CD45, CD90 and nucleostemin (NSTM) was higher in peritumoral than in distal adipose tissue and decreased in the presence of neoadjuvant therapy. Moreover, expression of NSTM, octamer‐binding transcription factor 4 (OCT‐4) and VEGF was higher in peritumoral (but not in distal) adipose tissue of chemoresistant patients. In ADSC, treatment with peritumoral adipose tissue CM increased the adipogenic potential and the expression of CD34, CD90, NSTM and OCT‐4. These effects were similar to those induced by cancer‐derived CM, but were not observed in ADSC treated with distal adipose tissue CM and were partially reduced by a leptin antagonist. Last, ADSC treated with peritumoral CM of chemoresistant patients displayed increased expression of NSTM, OCT‐4, leptin, leptin receptor, alpha‐smooth muscle actin (α‐SMA), CD34 and VEGF. These results suggest that peritumoral adipose tissue may promote, by paracrine signaling, the expression of depot‐specific factors associated with therapeutic resistance.

Cancer stem cells in colorectal cancer: a review

Colorectal cancer (CRC) is the second most common cancer in women and the third most common in men. Adenocarcinoma accounts for 90% of CRC cases. There has been accumulating evidence in support of the cancer stem cell (CSC) concept of cancer which proposes that CSCs are central in the initiation of cancer. CSCs have been the focus of study in a range of cancers, including CRC. This has led to the identification and understanding of genes involved in the induction and maintenance of pluripotency of stem cells, and markers for CSCs, including those investigated specifically in CRC. Knowledge of the expression pattern of CSCs in CRC has been increasing in recent years, revealing a heterogeneous population of cells within CRC ranging from pluripotent to differentiated cells, with overlapping and sometimes unique combinations of markers. This review summarises current literature on the understanding of CSCs in CRC, including evidence of the presence of CSC subpopulations, and the stem cell markers currently used to identify and localise these CSC subpopulations. Future research into this field may lead to improved methods for early detection of CRC, novel therapy and monitoring of treatment for CRC and other cancer types.

MiR-338-5p enhances the radiosensitivity of esophageal squamous cell carcinoma by inducing apoptosis through targeting survivin

Radioresistance is a challenge in the treatment of esophageal squamous cell carcinoma (ESCC). MicroRNAs (miRNAs) are known to play an important role in the functional modification of cancer cells and recent studies have reported miRNA-mediated radiotherapy resistance. However, further research is necessary to reveal the regulation mechanisms, and treatment strategies using miRNA are yet to be established for ESCC. We compared the miRNA expression profiles of ESCC parental (TE-4) and acquired radioresistance (TE-4R) cell lines using a miRNA microarray and qRT-PCR. Our data showed that miR-338-5p, one of the target miRNA biomarkers, was significantly downregulated in TE-4R. Ectopic overexpression of miR-338-5p induced apoptosis and sensitivity to radiation treatment by interfering with survivin, which is a known inhibitor of apoptosis. Overexpression of survivin reversed miR-338-5p-induced apoptosis. Tumor xenograft experiments indicated that therapeutic delivery of the miR-338-5p mimics via direct injection into tumor mass increased sensitivity to radiation therapy. In conclusion, our findings suggest that miR-338-5p is a potential radiosensitizer and may be a therapeutic biomarker for radioresistant in ESCC.

Tumor-associated NADH oxidase (tNOX)-NAD+-sirtuin 1 axis contributes to oxaliplatin-induced apoptosis of gastric cancer cells

Oxaliplatin belongs to the platinum-based drug family and has shown promise in cancer treatment. The major mechanism of action of platinum compounds is to form platinum–DNA adducts, leading to DNA damage and apoptosis. Accumulating evidence suggests that they might also target non-DNA molecules for their apoptotic activity. We explored the effects of oxaliplatin on a tumor-associated NADH oxidase (tNOX) in gastric cancer lines. In AGS cells, we found that the oxaliplatin-inhibited tNOX effectively attenuated the NAD⁺/NADH ratio and reduced the deacetylase activity of an NAD⁺-dependent sirtuin 1, thereby enhancing p53 acetylation and apoptosis. Similar results were also observed in tNOX-knockdown AGS cells. In the more aggressive MKN45 and TMK-1 lines, oxaliplatin did not inhibit tNOX, and induced only minimal apoptosis and cytotoxicity. However, the downregulation of either sirtuin 1 or tNOX sensitized TMK-1 cells to oxaliplatin-induced apoptosis. Moreover, tNOX-depletion in these resistant cells enhanced spontaneous apoptosis, reduced cyclin D expression and prolonged the cell cycle, resulting in diminished cancer cell growth. Together, our results demonstrate that oxaliplatin targets tNOX and SIRT1, and that the tNOX-NAD⁺-sirtuin 1 axis is essential for oxaliplatin-induced apoptosis.

Clinical value of octamer-binding transcription factor 4 as a prognostic marker in patients with digestive system cancers: A systematic review and meta-analysis

BACKGROUND AND AIM

The role of octamer-binding transcription factor 4 (Oct4) has been implicated in the clinical prognosis of various kinds of digestive system cancers, but the results remain controversial. The purpose of this meta-analysis is to assess the potential role of Oct4 as a prognostic marker in digestive system tumors.

METHODS

Relevant articles were retrieved from Pubmed, Web of Science, and Cochrane Library up to July 2016. The software Stata 12.0 was used to analyze the outcomes, including overall survival (OS), disease-free survival, recurrence-free survival, and clinicopathological characteristics.

RESULTS

A total of 13 eligible studies with 1538 patients were included. Elevated Oct4 expression was significantly associated with poor OS (pooled hazard ratio [HR] = 2.183, 95% confidence interval [CI]: 1.824-2.612), disease-free survival (pooled HR = 1.973, 95% CI: 1.538-2.532), and recurrence-free survival (pooled HR = 2.209, 95% CI: 1.461-3.338) of digestive system malignancies. Subgroup analyses showed that cancer type, sample size, study quality, and laboratory detection method did not alter the significant prognostic value of Oct4. Additionally, Oct4 expression was found to be an independent predictive factor for OS (HR = 2.068, 95% CI: 1.633-2.619). No significant association was found between Oct4 and clinicopathological features of digestive system malignancies.

CONCLUSION

This study provided evidence of Oct4 and/or its closely related homolog protein as a predictive factor for patients with digestive system cancers. More large-scale clinical studies on the prognostic value of Oct4 are warranted.

BEX3 contributes to cisplatin chemoresistance in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) can develop cisplatin‐resistant phenotype. Research has revealed that enriched in cancer stem cell population is involved in developing cisplatin‐resistant phenotype. CD271 is a candidate stem cell maker in head and neck cancers. The CD receptor does not possess any enzymatic property. Signal transduction function of CD271 is mediated by the cellular receptor‐associated protein. Our data showed that Brain‐expressed X‐linked 3 (BEX3), a CD271 receptor‐associated protein, was overexpressed in NPC. BEX3 overexpression was a unique event in cancer developed in the head and neck regions, especially NPC. BEX3 expression was inducible by cisplatin in NPC. In cisplatin‐resistant NPC xenograft, treatment with nontoxic level of cisplatin led to a remarkable increase in BEX3 level. High BEX3 expression was accompanied with high octamer‐binding transcription factor 4 (OCT4) expression in cisplatin‐resistant NPC. To confirm the inducing role of BEX3 on OCT4 expression, we knockdown BEX3 using siRNA and compared the expression of OCT4 with mock transfectants. Suppressing BEX3 transcripts led to a significant reduction in OCT4. In addition, targeting BEX3 using shRNA could increase the sensitivity of NPC cells to cisplatin. In summary, our results indicated a unique functional role of BEX3 in mediating the sensitivity of NPC cells to cisplatin. Targeting or blocking BEX3 activity might be useful in reversing the cisplatin‐resistant phenotype in NPC.

Acquisition of anticancer drug resistance is partially associated with cancer stemness in human colon cancer cells

Colorectal cancer (CRC) is one of the most aggressive cancers worldwide. Several anticancer agents are available to treat CRC, but eventually cancer relapse occurs. One major cause of chemotherapy failure is the emergence of drug-resistant tumor cells, suspected to originate from the stem cell compartment. The aim of this study was to ask whether drug resistance was associated with the acquisition of stem cell-like properties. We isolated drug-resistant derivatives of two human CRC cell lines, HT29 and HCT116, using two anticancer drugs with distinct modes of action, oxaliplatin and docetaxel. HT29 cells resistant to oxaliplatin and both HT29 and HCT116 cells resistant to docetaxel were characterized for their expression of genes potentially involved in drug resistance, cell growth and cell division, and by surveying stem cell-like phenotypic traits, including marker genes, the ability to repair cell-wound and to form colonospheres. Among the genes involved in platinum or taxane resistance (MDR1, ABCG2, MRP2 or ATP7B), MDR1 was uniquely overexpressed in all the resistant cells. An increase in the cyclin-dependent kinase inhibitor p21, in cyclin D1 and in CD26, CD166 cancer stem cell markers, was noted in the resistant cells, together with a higher ability to form larger and more abundant colonospheres. However, many phenotypic traits were selectively altered in either HT29- or in HCT116-resistant cells. Expression of EPHB2, ITGβ-1 or Myc was specifically increased in the HT29-resistant cells, whereas only HCT116-resistant cells efficiently repaired cell- wounds. Taken together, our results show that human CRC cells selected for their resistance to anticancer drugs displayed a few stem cell characteristics, a small fraction of which was shared between cell lines. The occurrence of marked phenotypic differences between HT29- and HCT116-drug resistant cells indicates that the acquired resistance depends mostly on the parental cell characteristics, rather than on the drug type used.

Down-regulation of S100A9 inhibits osteosarcoma cell growth through inactivating MAPK and NF-κB signaling pathways

Background

Osteosarcoma (OS) is well-known for poor prognosis due to its high incidence of proliferation and metastasis. Researches have provided valuable insights into the tumorigenesis of S100A9 in some cancers. We aimed to understand the expression level, functions and mechanisms of S100A9 in human osteosarcoma for the first time.

Methods

The expression of S100A9 protein was detected in 120 human osteosarcoma tissues and 40 normal human bone tissues using tissue microarrays analysis. The knockdown of S100A9 induced by RNA interference (RNAi) method in three osteosarcoma cell lines (U2OS, 143B, MG63) was applied to analyze the effects of S100A9 on cell proliferation, cell cycle distribution, migration, invasion and xenotransplanted tumors. Moreover, MAPK-ERK1/2, MAPK-p38, NF-κB-p65, NF-κB-p50, p21, p27, CDK2 and CDK4 were tested.

Results

The expression of S100A9 was increased in human osteosarcoma issues and was positively correlated with clinical classification and survival rate. Down-regulation of S100A9 inhibited OS cellular proliferation, migration, invasion and cell cycle S phase in vitro and suppressed tumor formation in vivo with the reduction on PCNA and Ki67 proliferation index. Our data also demonstrated that knockdown of S100A9 repressed the protein levels of phospho-ERK1/2, phospho-p50, phospho-p65 except phospho-p38, and prompted up-regulation of p21 and p27 leading to inactivation of cyclin dependent kinase 2(CDK2) and cyclin dependent kinase 4(CDK4).

Conclusions

S100A9 might be a significant role for predicting osteosarcoma prognosis and down-regulation of S100A9 could be used as a potential target for gene therapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2294-1) contains supplementary material, which is available to authorized users.

Mitochondrial Stat3, the Need for Design Thinking

Stat3 has been studied extensively as a transcription factor, however the finding that Stat3 also localizes to mitochondria has opened a new area to discover non-classical functions. Here we review the current knowledge of mitochondrial Stat3 as a regulator of the electron transport chain (ETC) and its impact on mitochondrial production of ATP and ROS. We also describe recent findings identifying Stat3 as a regulator of mitochondrial Ca(2+) homeostasis through its effect on the ETC. It is becoming evident that these non-classical functions of Stat3 can have a major impact on cancer progression, cardiovascular diseases, and inflammatory diseases. Therefore, mitochondrial Stat3 functions challenge the current design of therapies that solely target Stat3 as a transcription factor and suggest the need for "design thinking," which leads to the development of novel strategies, to intervene the Stat3 pathway.