The Role of CD44 and Cancer Stem Cells

In silico identification and in vitro validation of alpha-hederin as a potent inhibitor of Wnt/β-catenin signaling pathway in breast cancer stem cells

Cancer stem cells (CSCs) play a vital role in metastasis, recurrence and chemoresistance in breast cancer. β-catenin, which is a frequently over activated protein in CSCs, binds to T-cell factor/lymphoid enhancer factor (Tcf/Lef) family transcription factors leading to ectopic expression of Wnt pathway responsive genes necessary for the maintenance and action of CSCs. With the aim of identifying a small molecules that can effectively eliminate CSCs, molecular docking studies were performed against the Tcf/Lef binding hotspot on β-catenin using a library of 100 natural or synthetic small molecules. Small molecule ligands giving docking energy better than - 7 kcal/mol were further investigated by binding interactions analysis and molecular dynamics (MD) simulations. These compounds were then investigated in vitro, for cytotoxicity against CSCs isolated from MDA-MB-231 triple negative breast cancer cells. Alpha-hederin (AH) was identified as the only compound in the selected library that has cytotoxicity against breast CSCs. AH was further investigated for it's ability to regulate Wnt pathway target genes (Cyclin D1 and CD44)and the tumor suppressor p53by real-time quantitative PCR. Absorption, distribution, metabolism, excretion and toxicity properties of the AH was predicted in silico. AH significantly down regulated the transcription of Cyclin D1 and CD44 while up-regulating the transcription of p53. AH was predicted to have acceptable drug likeness. Although AH is currently known to inhibit the growth of various cancer cells in vitro, present study demonstrated for the first time that it is a potent inhibitor of Wnt/β-catenin signaling pathway and induce apoptosis in breast CSCs.

Predominant factors influencing reactive oxygen species in cancer stem cells

Reactive oxygen species (ROS) and its related signaling pathways and regulating molecules play a major role in the growth and development of cancer stem cells. The concept of ROS and cancer stem cells (CSCs) has been gaining much attention since the past decade and the evidence show that these CSCs possess robust self-renewal and tumorigenic potential and are resistant to conventional chemo- and radiotherapy and believed to be responsible for tumor progression, metastasis, and recurrence. It seems reasonable to say that cancer can be cured only if the CSCs are eradicated. ROS are Janus-faced molecules that can regulate cellular physiology as well as induce cytotoxicity, depending on the magnitude, duration, and site of generation. Unlike normal cancer cells, CSCs expel ROS efficiently by upregulating ROS scavengers. This unique redox regulation in CSCs protects them from ROS-mediated cell death and nullifies the effect of radiation, leading to chemoresistance and radioresistance. However, how these CSCs control ROS production by scavenging free radicals and how they maintain low levels of ROS is a challenging to understand and these attributes make CSCs as prime therapeutic targets. Here, we summarize the mechanisms of redox regulation in CSCs, with a focus on therapy resistance, its various pathways and microRNAs regulation, and the potential therapeutic implications of manipulating the ROS levels to eradicate CSCs. A better understanding of these molecules, their interactions in the CSCs may help us to adopt proper control and treatment measures.

Caveolin-1 mediates the utilization of extracellular proteins for survival in refractory gastric cancer

Despite advances in cancer therapy, the clinical outcome of patients with gastric cancer remains poor, largely due to tumor heterogeneity. Thus, finding a hidden vulnerability of clinically refractory subtypes of gastric cancer is crucial. Here, we report that chemoresistant gastric cancer cells rely heavily on endocytosis, facilitated by caveolin-1, for survival. caveolin-1 was highly upregulated in the most malignant stem-like/EMT/mesenchymal (SEM)-type gastric cancer cells, allowing caveolin-1-mediated endocytosis and utilization of extracellular proteins via lysosomal degradation. Downregulation of caveolin-1 alone was sufficient to induce cell death in SEM-type gastric cancer cells, emphasizing its importance as a survival mechanism. Consistently, chloroquine, a lysosomal inhibitor, successfully blocked caveolin-1-mediated endocytosis, leading to the marked suppression of tumor growth in chemorefractory gastric cancer cells in vitro, including patient-derived organoids, and in vivo. Together, our findings suggest that caveolin-1-mediated endocytosis is a key metabolic pathway for gastric cancer survival and a potential therapeutic target.

The Hyaluronan/CD44 Axis: A Double-Edged Sword in Cancer

Hyaluronic acid (HA) receptor CD44 is widely used for identifying cancer stem cells and its activation promotes stemness. Recent evidence shows that overexpression of CD44 is associated with poor prognosis in most human cancers and mediates therapy resistance. For these reasons, in recent years, CD44 has become a treatment target in precision oncology, often via HA-conjugated antineoplastic drugs. Importantly, HA molecules of different sizes have a dual effect and, therefore, may enhance or attenuate the CD44-mediated signaling pathways, as they compete with endogenous HA for binding to the receptors. The magnitude of these effects could be crucial for cancer progression, as well as for driving the inflammatory response in the tumor microenvironment. The increasingly common use of HA-conjugated drugs in oncology, as well as HA-based compounds as adjuvants in cancer treatment, adds further complexity to the understanding of the net effect of hyaluronan-CD44 activation in cancers. In this review, I focus on the significance of CD44 in malignancy and discuss the dichotomous function of the hyaluronan/CD44 axis in cancer progression.

Hyaluronic acid: More than a carrier, having an overpowering extracellular and intracellular impact on cancer

Hyaluronic acid (HA), also named hyaluronan, is an omnipresent component of the tissue microenvironment. It is extensively used to formulate targeted drug delivery systems for cancer. Although HA itself has pivotal influences in various cancers, its calibers are somewhat neglected when using it as delivering platform to treat cancer. In the last decade, multiple studies revealed roles of HA in cancer cell proliferation, invasion, apoptosis, and dormancy through pathways like mitogen-activated protein kinase-extracellular signal-regulated kinase (MAPK/ERK), P³⁸, and nuclear factor kappa-light chain-enhancer of activated B cells (NFκB). A more fascinating fact is that the distinct molecular weight (MW) of HA exerts disparate effects on the same type of cancer. Its overwhelming use in cancer therapy and other therapeutic products make collective research on the sundry impact of it on various types of cancer, an essential aspect to be considered in all of these domains. Even the development of new therapies against cancer needed meticulous studies on HA because of its divergence of activity based on MW. This review will provide painstaking insight into the extracellular and intracellular bioactivity of HA, its modified forms, and its MW in cancers, which may improve the management of cancer.

The role of tumor microenvironment on cancer stem cell fate in solid tumors

In the last few decades, the role of cancer stem cells in initiating tumors, metastasis, invasion, and resistance to therapies has been recognized as a potential target for tumor therapy. Understanding the mechanisms by which CSCs contribute to cancer progression can help to provide novel therapeutic approaches against solid tumors. In this line, the effects of mechanical forces on CSCs such as epithelial-mesenchymal transition, cellular plasticity, etc., the metabolism pathways of CSCs, players of the tumor microenvironment, and their influence on the regulating of CSCs can lead to cancer progression. This review focused on some of these mechanisms of CSCs, paving the way for a better understanding of their regulatory mechanisms and developing platforms for targeted therapies. While progress has been made in research, more studies will be required in the future to explore more aspects of how CSCs contribute to cancer progression. Video Abstract.

RNA Transcripts in Human Ovarian Cells: Two-Time Cryopreservation Does Not Affect Developmental Potential

Sometimes, for medical reasons, when a frozen tissue has already thawed, an operation by re-transplantation may be cancelled, and ovarian tissues should be re-frozen for transplantation next time. Research about the repeated cryopreservation of ovarian cells is rarely reported. It has been published that there is no difference in the follicle densities, proportions of proliferation of early preantral follicles, appearance of atretic follicles, or ultrastructural quality of frozen-thawed and re-frozen-rethawed tissue. However, the molecular mechanisms of a repeated cryopreservation effect on the developmental potential of ovarian cells are unknown. The aim of our experiments was to investigate the effect of re-freezing and re-thawing ovarian tissue on gene expression, gene function annotation, and protein-protein interactions. The morphological and biological activity of primordial, primary, and secondary follicles, aimed at using these follicles for the formation of artificial ovaries, was also detected. Second-generation mRNA sequencing technology with a high throughput and accuracy was adopted to determine the different transcriptome profiles in the cells of four groups: one-time cryopreserved (frozen and thawed) cells (Group 1), two-time cryopreserved (re-frozen and re-thawed after first cryopreservation) cells (Group 2), one-time cryopreserved (frozen and thawed) and in vitro cultured cells (Group 3), and two times cryopreserved (re-frozen and re-thawed after first cryopreservation) and in vitro cultured cells (Group 4). Some minor changes in the primordial, primary, and secondary follicles in terms of the morphology and biological activity were detected, and finally, the availability of these follicles for the formation of artificial ovaries was explored. It was established that during cryopreservation, the CEBPB/CYP19A1 pathway may be involved in regulating estrogen activity and CD44 is crucial for the development of ovarian cells. An analysis of gene expression in cryopreserved ovarian cells indicates that two-time (repeated) cryopreservation does not significantly affect the developmental potential of these cells. For medical reasons, when ovarian tissue is thawed but cannot be transplanted, it can be immediately re-frozen again.

A type I AIE photosensitiser-loaded biomimetic nanosystem allowing precise depletion of cancer stem cells and prevention of cancer recurrence after radiotherapy

Radioresistance of Cancer stem cell (CSC) is an important cause of tumor recurrence after radiotherapy (RT). Herein, we designed a type I aggregation-induced emission (AIE) photosensitiser-loaded biomimetic mesoporous organosilicon nanosystem (PMT) for precise depletion of CSC to prevent tumor recurrence after RT. This PMT system is composed of a type I AIE photosensitiser (TBP-2) loaded mesoporous organosilicon nanoparticles (MON) with an outer platelet membrane. The PMT system is able to specifically target CSC. Intracellular glutathione activity leads to MON degradation and the release of TBP-2. Type I photodynamic therapy is activated by exposure to white light, producing a large amount of hydroxyl radicals to promote CSC death. The results of in vivo experiments demonstrated specific removal of CSC following PMT treatment, with no tumor recurrence observed when combined with RT. However, tumor recurrence was observed in mice that received RT only. The expression of CSC markers was significantly reduced following PMT treatment. We demonstrate the development of a system for the precise removal of CSC with good biosafety and high potential for clinical translation. We believe the PMT nanosystem represents a novel idea in the prevention of tumor recurrence.

TRRAP Enhances Cancer Stem Cell Characteristics by Regulating NANOG Protein Stability in Colon Cancer Cells

NANOG, a stemness-associated transcription factor, is highly expressed in many cancers and plays a critical role in regulating tumorigenicity. Transformation/transcription domain-associated protein (TRRAP) has been reported to stimulate the tumorigenic potential of cancer cells and induce the gene transcription of NANOG. This study aimed to investigate the role of the TRRAP-NANOG signaling pathway in the tumorigenicity of cancer stem cells. We found that TRRAP overexpression specifically increases NANOG protein stability by interfering with NANOG ubiquitination mediated by FBXW8, an E3 ubiquitin ligase. Mapping of NANOG-binding sites using deletion mutants of TRRAP revealed that a domain of TRRAP (amino acids 1898–2400) is responsible for binding to NANOG and that the overexpression of this TRRAP domain abrogated the FBXW8-mediated ubiquitination of NANOG. TRRAP knockdown decreased the expression of CD44, a cancer stem cell marker, and increased the expression of P53, a tumor suppressor gene, in HCT-15 colon cancer cells. TRRAP depletion attenuated spheroid-forming ability and cisplatin resistance in HCT-15 cells, which could be rescued by NANOG overexpression. Furthermore, TRRAP knockdown significantly reduced tumor growth in a murine xenograft transplantation model, which could be reversed by NANOG overexpression. Together, these results suggest that TRRAP plays a pivotal role in the regulation of the tumorigenic potential of colon cancer cells by modulating NANOG protein stability.

Negative regulation of CD44st by miR-138-5p affects the invasive ability of breast cancer cells and patient prognosis after breast cancer surgery

OBJECTIVE

To investigate how the negative regulation of CD44st by miR-138-5p affects the invasive ability of breast cancer cell lines and prognosis in postoperative breast cancer patients.

METHODS

RT-PCR, qRT-PCR, and western blot assays were used to detect the expression of CD44s, CD44v6, and CD44st at both mRNA and protein levels. The expression of miR-138-5p in breast cancer cell lines was also evaluated. The binding ability of miR-138-5p to CD44st was determined via a dual-luciferase assay. The CD44 protein expression in breast cancer tissues was detected using immunohistochemistry. A Transwell assay was used to detect the invasive ability of tumor cells. The correlation between CD44st and miR-138-5p mRNA expression in breast cancer tissues was evaluated using qRT-PCR, and the relationship between clinicopathological features was statistically analyzed.

RESULTS

CD44s and CD44v6 were highly expressed in MDAMB-231 cell line, while CD44st was highly expressed in MCF-7/Adr and Skbr-3 cells. None of the CD44 isoforms were expressed in MCF-7 cells. The miR-138-5p was highly expressed in MCF-7 cells, but not in MCF-7/Adr, Skbr-3, and MDAMB-231 cells. The dual-luciferase assay suggested that miR-138-5p could bind to wild-type CD44st 3'-UTR, miR-138-5p overexpression significantly inhibited the expression level of CD44 protein in MCF-7/Adr cells, and miR-138-5p + CD44st (3'-UTR)-treated MCF-7/Adr and Skbr-3 cells were significantly less invasive than those in the control group (P < 0.05). RT-PCR results for 80 postoperative breast cancer patients showed that the mRNA expression rate for CD44st was higher in cancer tissues than in paracancerous tissues, and the expression rate of miR-138-5p was higher in paracancerous tissues than in cancerous tissues (P < 0.01). In cancer tissues, CD44st was negatively correlated with miR-138-5p expression, with correlation coefficient r = -0.76 (Pearson's correlation), coefficient of determination R2 = 0.573, F = 106.89, and P < 0.001. The median overall survival value for patients in the low miR-138-5p expression group was 40.39 months [95% confidence interval (CI): 35.59-45.18 months] and 56.30 months (95% CI: 54.38-58.21 months) for patients in the high-expression group, with a log rank (Mantel-Cox) of 13.120, one degree of freedom, and P < 0.001.

CONCLUSION

In breast cancer cell lines, miR-138-5p negatively regulated expression of CD44st and affected the invasive ability of tumor cells and patient prognosis after breast cancer surgery.

Electrostatic potential difference between tumor and paratumor regulates cancer stem cell behavior and prognose tumor spread

Tumor spread is responsible for most deaths related to cancer. Increasing the accuracy of cancer prognosis is critical to reducing the high mortality rates in cancer patients. Here, we report that the electrostatic potential difference (EPD) between tumor and its paratumor tissue is a prognostic marker for tumor spread. This finding is concluded from the patient-specific EPD values and clinical observation. The electrostatic potential values were measured on tissue cryosections from 51 patients using Kelvin probe force microscopy (KPFM). A total of ~44% (15/34) patients of V_{tumor-paratumor} > 0 were featured with tumor spread, whereas only ~18% (2/11) patients of V_{tumor-paratumor} < 0 had tumor spread. Next, we found the increased enrichment of cancer stem cells in paratumors with lower electrostatic potentials using immunofluorescence imaging, which suggested the attribution of tumor spread to the galvanotaxis of cancer stem cells (CSCs) toward lower potential. The findings were finally validated in breast and lung spheroid models composed of differentiated cancer cells and cancer stem cells at the ratio of 1:1 and embedded in Matrigel dopped with negative-, neutral- and positive-charged polymers and CSCs prefer to spread out of spheroids to lower electrostatic potential sites. This work may inspire the development of diagnostic and prognostic strategies targeting at tissue EPDs and CSCs for tumor therapy.

Thioalbamide inhibits F(o)F(1)-ATPase in breast cancer cells and reduces tumor proliferation and invasiveness in breast cancer in vivo models

OBJECTIVE

Thioalbamide is a ribosomally synthesized and post-translationally modified peptide (RiPP) belonging to the family of thioamitides, a rare class of microbial specialized metabolites with unusual post-translational modifications and promising biological activities. Recent studies have demonstrated the ability of thioalbamide to exert highly selective cytotoxic effects on tumor cells by affecting their energy metabolism, thus causing abnormal ROS production and triggering apoptosis. This study is aimed to investigate the molecular mechanisms underlying the antitumor activity of thioalbamide in order to identify its exact molecular target.

METHODS

Wild type MCF-7 and MDA-MB-231 breast cancer cell lines as well as cancer cells deprived of mitochondrial DNA (ρ⁰ cells) were employed in order to assess thioalbamide effects on tumor bioenergetics. In this regard, metabolic profile was evaluated by a Seahorse XFe96 analyzer, and the activity of the enzyme complexes involved in oxidative phosphorylation was quantified by spectrophotometric assays. Thioalbamide effects on tumor invasiveness were assessed by gelatin zymography experiments and invasion assays. In vivo experiments were carried out on breast cancer xenograft and "experimental metastasis" mouse models.

RESULTS

Experiments carried out on ρ⁰ breast cancer cells, together with Seahorse analysis and the application of spectrophotometric enzymatic assays, highlighted the ability of thioalbamide to affect the mitochondrial respiration process, and allowed to propose the F_oF₁-ATPase complex as its main molecular target in breast cancer cells. Additionally, thioalbamide-mediated OXPHOS inhibition was shown, for the first time, to reduce tumor invasiveness by inhibiting metalloproteinase-9 secretion. Furthermore, this study has confirmed the antitumor potential of thioalbamide in two different in vivo models. In particular, experiments on MCF-7 and MDA-MB-231 xenograft mouse models have confirmed in vivo its high anti-proliferative and pro-apoptotic activity, while experiments on MDA-MB-231 ″experimental metastasis" mouse models have highlighted its ability to inhibit breast cancer cell invasiveness.

CONCLUSIONS

Overall, our results shed more light on the molecular mechanisms underlying the pharmacological potential of thioamidated peptides, thus reducing the gap that separates this rare class of microbial metabolites from clinical studies, which could validate them as effective tools for cancer treatment.

Tumor lysis syndrome promotes cancer chemoresistance and relapse through AMPK inhibition

Cancer is a disease caused when cells divide uncontrollably and spread into surrounding tissues. There are different therapeutic modalities that control cancer growth, of which surgery, chemotherapy, and radiotherapy. Chemotherapy is a cancer treatment approach in which medications are used to inhibit cell proliferation and tumor multiplication, thus avoiding invasion and metastasis and thus eradicate cancer. One of the common complications associated with cancer chemotherapy is rapid lysis of expanding tumor cells, known as tumor lysis syndrome (TLS). TLS is associated with number of metabolic changes such as hyperuricemia, hyperkalemia, hyperphosphatemia and hypocalcemia. Among the consequences of hyperuricemia, hyperkalemia, hyperphosphatemia and hypocalcemia is the inhibition of 5' AMP-activated protein kinase (AMPK). Inhibition of AMPK induced different cancer chemo-resistance mechanisms such as cancer stem cells (CSCs), p-glycoproteins, Octamer-binding transcription factor 4 (OCT-4), homeobox protein NANOG, Krüppel-like factor 4 (KLF4) and immune microenvironment and thus leads to poor response to chemotherapy and even relapses after treatment. Our review aims to uncover new mechanisms underlying the metabolic consequences of tumor lysis on AMPK in tumor microenvironment. In this review, we also investigated the effect of AMPK on different cancer chemo-resistance mechanisms such as cancer stem cells, p-glycoproteins, OCT-4, NANOG, KLF4 and immune microenvironment.

Twist1 as a target for prevention of cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) represents an important clinical problem requiring novel approaches for both prevention and treatment. The transcription factor, Twist-related protein 1 (Twist1), has been identified as having a key mechanistic role in the development and progression of cSCC. Studies in relevant mouse models of cSCC have shown that Twist1 regulates epithelial-mesenchymal transition (EMT) and stemness driving progression and metastasis of cSCC. In addition, further research has shown that Twist1 regulates the balance between keratinocyte proliferation and differentiation and therefore impacts earlier stages of cSCC development. Through use of keratinocyte specific Twist1 knockout models, a role for this gene in keratinocyte stem cell homeostasis has been revealed. As a transcription factor, Twist1 regulates a large number of genes both in a positive, as well as a negative manner across several interdependent pathways. Studies in keratinocyte specific knockout models have shown that Twist1 upregulates the expression of genes involved in proliferation, stemness, and EMT while downregulating the expression of genes associated with differentiation. Furthermore, a number of compounds, including naturally occurring compounds, have been identified that target Twist1 and can block its effects in cancer cells and in keratinocytes in vivo. Collectively, the current understanding of Twist1 function in cSCC development and progression suggests that it represents a potential target for prevention and treatment of cSCC.

Breaking the niche: multidimensional nanotherapeutics for tumor microenvironment modulation

Most of the current antitumor therapeutics were developed targeting the cancer cells only. Unfortunately, in the majority of tumors, this single-dimensional therapy is found to be ineffective. Advanced research has shown that cancer is a multicellular disorder. The tumor microenvironment (TME), which is made by a complex network of the bulk tumor cells and other supporting cells, plays a crucial role in tumor progression. Understanding the importance of the TME in tumor growth, different treatment modalities have been developed targeting these supporting cells. Recent clinical results suggest that simultaneously targeting multiple components of the tumor ecosystem with drug combinations can be highly effective. This type of "multidimensional" therapy has a high potential for cancer treatment. However, tumor-specific delivery of such multi-drug combinations remains a challenge. Nanomedicine could be utilized for the tumor-targeted delivery of such multidimensional therapeutics. In this review, we first give a brief overview of the major components of TME. We then highlight the latest developments in nanoparticle-based combination therapies, where one drug targets cancer cells and other drug targets tumor-supporting components in the TME for a synergistic effect. We include the latest preclinical and clinical studies and discuss innovative nanoparticle-mediated targeting strategies.

Molecular Biomarkers of Malignant Transformation in Head and Neck Dysplasia

Head and neck squamous cell carcinoma (HNSCC) and its treatments are associated with substantial morbidity, often resulting in cosmetic deformity and loss of physiologic functions including speech and swallowing. Despite advancements in treatment, 5-year survival rates for mucosal malignancies remain below 70%. Effective prevention of HNSCC demands an understanding of the molecular pathways of carcinogenesis. Specifically, defining features of pre-cancerous dysplastic lesions that indicate a better or worse prognosis is necessary to help identify patients who are likely to develop a carcinoma and allow a more aggressive approach to management. There remains a need for identification of biomarkers that can provide both early prognostic and predictive value in clinical decision-making by serving as both therapeutic targets as well as predictors of therapy response. Here, we comprehensively review the most frequently altered molecular biomarkers of malignant transformation in head and neck dysplasia. These markers are involved in a wide range of cellular processes in head and neck carcinogenesis, including extracellular matrix degradation, cell motility and invasion, cell-cell adhesion, solute transport, immortalization, metabolism, the cell cycle and apoptosis, transcription, and cell signaling.

CD44v6+ Hepatocellular Carcinoma Cells Maintain Stemness Properties through Met/cJun/Nanog Signaling

Cancer stem cells (CSCs) are characterized by their self-renewal and differentiation abilities. CD44v6 is a novel CSC marker that can activate various signaling pathways. Here, we hypothesized that the HGF/Met signaling pathway promotes stemness properties in CD44v6+ hepatocellular carcinoma (HCC) cells via overexpression of the transcription factor, cJun, thus representing a valuable target for HCC therapy. Magnetic activated cell sorting was used to separate the CD44v6+ from CD44v6- cells, and Met levels were regulated using lentiviral particles and the selective Met inhibitor, PHA665752. An orthotopic liver xenograft tumor model was used to assess the self-renewal ability of CD44v6+ cells in immunodeficient NOD/SCID mice. Luciferase reporter and chromatin immunoprecipitation assays were also conducted using cJun-overexpressing 293 T cells to identify the exact binding site of cJun in the Nanog promoter. Our data demonstrate that CD44v6 is an ideal surface marker of liver CSCs. CD44v6+ HCC cells express higher levels of Met and possess self-renewal and tumor growth abilities. Xenograft liver tumors were smaller in nude mice injected with shMet HCC cells. Immunohistochemical analysis of liver tissue specimens revealed that high Met levels in HCC cells were associated with poor patient prognosis. Further, a cJun binding site was identified 1700 bp upstream of the Nanog transcription start site and mutation of the cJun binding site reduced Nanog expression. In conclusion, the HGF/Met signaling pathway is important for maintenance of stemness in CD44v6+ HCC cells by enhancing expression of cJun, which binds 1700 bp upstream of the Nanog transcription start site.

Potential Application of Small Interfering RNA in Gastro-Intestinal Tumors

Despite the progress made in the diagnoses and therapy of gastrointestinal cancers, these diseases are still plagued by a high mortality. Thus, novel therapeutic approaches are urgently required. In this regard, small interfering RNA (siRNA), double-stranded RNA molecules able to specifically target the mRNA of pathological genes, have the potential to be of therapeutic value. To be effective in the human body, siRNAs need to be protected against degradation. Additionally, they need to target the tumor, leaving the normal tissue untouched in an effort to preserve organ function. To accomplish these tasks, siRNAs have been formulated with smart delivery systems such has polymers and lipids. While siRNA protection is not particularly difficult to achieve, their targeting of tumor cells remains problematic. Here, after introducing the general features of gastrointestinal cancers, we describe siRNA characteristics together with representative delivery systems developed for gastrointestinal cancers. Afterward, we present a selection of research papers employing siRNAs against upper- and lower- gastrointestinal cancers. For the liver, we also consider papers using siRNAs to combat liver cirrhosis, a relevant risk factor for liver cancer development. Finally, we present a brief description of clinical trials employing siRNAs for gastrointestinal cancers.

Cancer Stem Cell Derived Extracellular Vesicles with Self-Functionalized 3D Nanosensor for Real-Time Cancer Diagnosis: Eliminating the Roadblocks in Liquid Biopsy

Liquid biopsy for determining the presence of cancer and the underlying tissue of origin is crucial to overcome the limitations of existing tissue biopsy and imaging-based techniques by capturing critical information from the dynamic tumor heterogeneity. A newly emerging liquid biopsy with extracellular vesicles (EVs) is gaining momentum, but its clinical relevance is in question due to the biological and technical challenges posed by existing technologies. The biological barriers of existing technologies include the inability to generate fundamental details of molecular structure, chemical composition as well as functional variations in EVs by gathering simultaneous information on multiple intra-EV molecules, unavailability of holistic qualitative analysis, in addition to the inability to identify tissue of origin. Technological barriers include reliance on EV isolation with a few labeled biomarkers, resulting in the inability to generate comprehensive information on the disease. A more favorable approach would be to generate holistic information on the disease without the use of labels. Such a marker-free diagnosis is impossible with the existing liquid biopsy due to the unavailability clinically validated cancer stem cells (CSC)-specific markers and dependence of existing technologies on EV isolation, undermining the clinical relevance of EV-based liquid biopsy. Here, CSC EVs were employed as an independent liquid biopsy modality. We hypothesize that tracking the signals of CSCs in peripheral blood with CSC EVs will provide a reliable solution for accurate cancer diagnosis, as CSC are the originators of tumor contributing to tumor heterogeneity. We report nanoengineered 3D sensors of extremely small nano-scaled probes self-functionalized for SERS, enabling integrative molecular and functional profiling of otherwise undetectable CSC EVs. A substantially enhanced SERS and ultralow limit of detection (10 EVs per 10 μL) were achieved. This was attributed to the efficient probe-EV interaction due to the 3D networks of nanoprobes, ensuring simultaneous detection of multiple EV signals. We experimentally demonstrate the crucial role of CSC EVs in cancer diagnosis. We then completed a pilot validation of this modality for cancer detection as well as for identification of the tissue of origin. An artificial neural network distinguished cancer from noncancer with 100% sensitivity and 100% specificity for three hard to detect cancers (breast, lung, and colorectal cancer). Binary classification to distinguish one tissue of origin against all other achieved 100% accuracy, while simultaneous identification of all three tissues of origin with multiclass classification achieved up to 79% accuracy. This noninvasive tool may complement existing cancer diagnostics, treatment monitoring as well as longitudinal disease monitoring by validation with a large cohort of clinical samples.

The inhibitory effect and mechanism of Yi-qi-hua-yu-jie-du decoction on the drug resistance of gastric cancer stem cells based on ABC transporters

Background

The drug resistance of tumor stem cells is an obstacle in gastric cancer (GC) treatment and the high expression of ABC transporters is a classic reason for drug resistance. This study aimed to construct a reliable GC drug-resistant stem cell model and explore the inhibitory effect and mechanism of Yi-qi-hua-yu-jie-du medicated serum (YQHY) on the drug resistance of GC stem cells based on ABC transporters.

Methods

The tumor stemness biomarker CD44 was primary identification from WGCNA. The magnetic-activated cell sorting (MACS) method was used to separate CD44( +)BGC823/5-Fu (BGC823/5–Fu-CSCs) cells and the stemness characteristics were verified from multiple dimensions. Then, the drug resistance index and expression of ABC transporter genes MDR1 and MRP1 were detected in CD44(−)/CD44(+) cells. The inhibition and apoptosis rates of the cells administrated with YQHY or/and 5-Fu were calculated to confirm that YQHY can suppress the drug resistance of BGC823/5-Fu-CSCs. Afterwards, the effects of YQHY on the expression of MDR1 and MRP1 and the activation of the PI3K/Akt/Nrf2 pathway were observed. Finally, under the administration of IGF-1 (the activator of PI3K/Akt pathway) and Nrf2 siRNA, the mechanism of YQHY on reversing the drug resistance of BGC823/5–Fu-CSCs through inhibiting the expression of MDR1 and MRP1 via PI3K/Akt/Nrf2 was verified.

Results

CD44 was a reliable GC stemness biomarker and can be applied to construct the drug-resistant GC stem cell model CD44(+)BGC823/5-Fu. The growth rate, cell proliferation index, soft agar colony formation, expression of stemness specific genes and tumorigenesis ability of CD44(+)BGC823/5-Fu cells were significantly higher than those of CD44(−)BGC823/5-Fu cells. BGC823/5–Fu-CSCs exhibited strong drug resistance to 5-Fu and high expression of ABC transporter genes MDR1 and MRP1 compared to CD44(-) cells. YQHY increased the inhibition and apoptosis rates to efficiently inhibit the drug resistance of BGC823/5–Fu-CSCs. Meanwhile, it suppressed the expression of MDR1 and MRP1 and restrained the activation of PI3K/Akt/Nrf2 signaling pathway. Finally, it was found that IGF-1 partially restored the activation of PI3K/Akt/Nrf2 pathway, alleviated the inhibition of MDR1 and MRP1, blocked the proliferation-inhibitory and apoptosis-promotion effects. YQHY and si-Nrf2 synergistically suppressed the MDR1/MRP1 expression and the drug resistance of BGC823/5–Fu-CSCs.

Conclusions

CD44 was a reliable GC stemness biomarker, and the high expression of ABC transporter genes MDR1 and MRP1 was an important feature of drug-resistant stem cells. YQHY inhibited the MDR1 and MRP1 expression via PI3K/Akt/Nrf2 pathway, thus reversing the drug resistance of BGC823/5–Fu-CSCs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-022-00647-y.

CD44 Glycosylation as a Therapeutic Target in Oncology

The interaction of non-kinase transmembrane glycoprotein CD44 with ligands including hyaluronic acid (HA) is closely related to the occurrence and development of tumors. Changes in CD44 glycosylation can regulate its binding to HA, Siglec-15, fibronectin, TM4SF5, PRG4, FGF2, collagen and podoplanin and activate or inhibit c-Src/STAT3/Twist1/Bmi1, PI3K/AKT/mTOR, ERK/NF-κB/NANOG and other signaling pathways, thereby having a profound impact on the tumor microenvironment and tumor cell fate. However, the glycosylation of CD44 is complex and largely unknown, and the current understanding of how CD44 glycosylation affects tumors is limited. These issues must be addressed before targeted CD44 glycosylation can be applied to treat human cancers.

The uptake of metal-organic frameworks: a journey into the cell

The application of metal-organic frameworks (MOFs) in drug delivery has advanced rapidly over the past decade, showing huge progress in the development of novel systems. Although a large number of versatile MOFs that can carry and release multiple compounds have been designed and tested, one of the main limitations to their translation to the clinic is the limited biological understanding of their interaction with cells and the way they penetrate them. This is a crucial aspect of drug delivery, as MOFs need to be able not only to enter into cells but also to release their cargo in the correct intracellular location. While small molecules can enter cells by passive diffusion, nanoparticles (NPs) usually require an energy-dependent process known as endocytosis. Importantly, the fate of NPs after being taken up by cells is dependent on the endocytic pathways they enter through. However, no general guidelines for MOF particle internalization have been established due to the inherent complexity of endocytosis as a mechanism, with several factors affecting cellular uptake, namely NP size and surface chemistry. In this review, we cover recent advances regarding the understanding of the mechanisms of uptake of nano-sized MOFs (nanoMOFs)s, their journey inside the cell, and the importance of biological context in their final fate. We examine critically the impact of MOF physicochemical properties on intracellular trafficking and successful cargo delivery. Finally, we highlight key unanswered questions on the topic and discuss the future of the field and the next steps for nanoMOFs as drug delivery systems.

Tumor budding of cervical squamous cell carcinoma: epithelial-mesenchymal transition-like cancer stem cells?

Recent evidence indicates that cancer stem cells (CSCs) are the origin of cancers. Scientists have identified CSCs in various tumors and have suggested the existence of a variety of states of CSCs. The existence of epithelial-mesenchymal transition (EMT)-like CSCs has been confirmed in vitro, but they have not been identified in vivo. Tumor budding was defined as single cell or clusters of ≤ 5 cells at the invasive front of cancers. Such tumor budding is hypothesized to be closely related to EMT and linked to CSCs, especially to those migrating at the invasive front. Therefore, tumor budding has been proposed to represent EMT-like stem cells. However, this hypothesis has not yet been proven. Thus, we studied the expression of EMT markers, certain CSC markers of tumor budding, and the tumor center of cervical squamous cell carcinoma (CxSCC). We performed tissue chip analyses of 95 primary CxSCCs from patients. Expression of EMT and CSC markers (E-cadherin, β-catenin, vimentin, Ki67, CD44, SOX2 , and ALDH1A1) in a set of tumor samples on tissue chips (87 cases of tumor budding/the main tumor body) were evaluated by immunohistochemistry. We found that the cell-membranous expression of β-catenin was stronger in the main tumor body than in tumor buds. Compared with the main tumor body, tumor buds had reduced proliferative activity as measured by Ki67. Moreover, vimentin expression was high and E-cadherin expression was low in tumor buds. Expression of EMT-related markers suggested that tumor buds were correlated with EMT. We noted that CxSCC tumor buds had a CD44negative/low/SOX2high/ALDH1A1high staining pattern, indicating that tumor buds of CxSCC present CSC-like immunophenotypic features. Taken together, our data indicate that tumor buds in CxSCC may represent EMT-like CSCs in vivo.

Regulation of Tissue Factor by CD44 Supports Coagulant Activity in Breast Tumor Cells

Simple Summary

Metastasis and thromboembolic complications are the main cause of cancer-associated death. An overexpression of coagulation factors, and particularly Tissue factor, by tumor cells is a key event implicated in this observed hypercoagulability. Tissue Factor is indeed a cellular initiator of the coagulation cascade which has been associated with aggressive tumor phenotypes such as those characteristic of Epithelial-Mesenchymal Transitions (EMTs) and Cancer Stem Cells (CSCs). Understanding molecular mechanisms controlling Tissue Factor overexpression in those tumor phenotypes is thus an important aspect of cancer research. We show here that CD44 (a transmembrane marker of CSC and EMT phenotypes) contributes to regulate TF expression at a transcriptional level, thereby supporting procoagulant properties in tumor cells that facilitate their metastatic spread.

Abstract

Previous work identified Tissue Factor (TF), a key activator of the coagulation cascade, as a gene induced in cellular contexts of Epithelial-Mesenchymal Transitions (EMTs), providing EMT⁺ Circulating Tumor Cells (CTCs) with coagulant properties that facilitate their metastatic seeding. Deciphering further molecular aspects of TF regulation in tumor cells, we report here that CD44 and TF coexpress in EMT contexts, and that CD44 acts as a regulator of TF expression supporting procoagulant properties and metastatic seeding. A transcriptional regulatory mechanism bridging CD44 to TF expression was further evidenced. Comparing different TF –promoter luciferase reporter constructs, we indeed found that the shortest -111 pb TF promoter fragment harboring three Specificity Protein 1 (Sp1) binding sites is still responsive to CD44 silencing. The observation that (i) mutation within Sp1 binding sites decreased the basal activity of the -111 pb TF promoter construct, (ii) CD44 silencing decreased Sp1 protein and mRNA levels and (iii) Sp1 silencing diminished TF expression further points to Sp1 as a key mediator linking CD44 to TF regulation. All together, these data thus report a transcriptional regulatory mechanism of TF expression by CD44 supporting procoagulant activity and metastatic competence of CTCs.

The Route of the Malignant Plasma Cell in Its Survival Niche: Exploring “Multiple Myelomas”

Growing evidence points to multiple myeloma (MM) and its stromal microenvironment using several mechanisms to subvert effective immune and anti-tumor responses. Recent advances have uncovered the tumor-stromal cell influence in regulating the immune-microenvironment and have envisioned targeting these suppressive pathways to improve therapeutic outcomes. Nevertheless, some subgroups of patients include those with particularly unfavorable prognoses. Biological stratification can be used to categorize patient-, disease- or therapy-related factors, or alternatively, these biological determinants can be included in a dynamic model that customizes a given treatment to a specific patient. Genetic heterogeneity and current knowledge enforce a systematic and comprehensive bench-to-bedside approach. Given the increasing role of cancer stem cells (CSCs) in better characterizing the pathogenesis of solid and hematological malignancies, disease relapse, and drug resistance, identifying and describing CSCs is of paramount importance in the management of MM. Even though the function of CSCs is well-known in other cancer types, their role in MM remains elusive. With this review, we aim to provide an update on MM homing and resilience in the bone marrow micro milieu. These data are particularly interesting for clinicians facing unmet medical needs while designing novel treatment approaches for MM.

TNF-α-inducing protein of Helicobacter pylori promotes EMT and cancer stem-like cells properties via activation of Wnt/β-catenin signaling pathway in gastric cancer cells

Tumor necrosis factor-α-inducing protein (Tipα) is a newly identified toxin, which promotes the inflammation and carcinogenesis caused by Helicobacter pylori (H. pylori). However, its mechanism of pathogenesis is still unclear. To investigate the carcinogenic mechanisms of Tipα, SGC7901 cells and SGC7901-derived cancer stem-like cells (CSCs) were stimulated by recombinant Tipα protein with or without Wnt/β-catenin signaling inhibitor XAV939. qRT-PCR and Western blotting were employed to detect expression of epithelial-mesenchymal transition (EMT), CSCs markers, and downstream target genes of this signaling pathway. The cell migration ability was measured by wound healing assay and transwell assay. Our results indicated that Tipα promoted CSC properties of SGC7901 spheroids, including increased expression of CSC specific surface markers CD44, Oct4, Nanog, and an increased capacity for self-renewal. Tipα activated Wnt/β-catenin signaling in both SGC7901 cells or CSCs. Furthermore, Tipα induced the EMT and increased the expressions of downstream target genes of this signaling, including c-myc, cyclin D1, and CD44. However, XAV939 pretreatment inhibited Tipα-induced EMT and CSC properties in SGC7901 cells or CSCs. These results suggest that Tipα promotes EMT and CSC-like properties in gastric cancer cells through activation of Wnt/β-catenin signaling pathway, thereby accelerating the progression of gastric cancer.

Revealing the human mucinome

Mucin domains are densely O-glycosylated modular protein domains found in various extracellular and transmembrane proteins. Mucin-domain glycoproteins play important roles in many human diseases, such as cancer and cystic fibrosis, but the scope of the mucinome remains poorly defined. Recently, we characterized a bacterial O-glycoprotease, StcE, and demonstrated that an inactive point mutant retains binding selectivity for mucin-domain glycoproteins. In this work, we leverage inactive StcE to selectively enrich and identify mucin-domain glycoproteins from complex samples like cell lysate and crude ovarian cancer patient ascites fluid. Our enrichment strategy is further aided by an algorithm to assign confidence to mucin-domain glycoprotein identifications. This mucinomics platform facilitates detection of hundreds of glycopeptides from mucin domains and highly overlapping populations of mucin-domain glycoproteins from ovarian cancer patients. Ultimately, we demonstrate our mucinomics approach can reveal key molecular signatures of cancer from in vitro and ex vivo sources.

Mucin-domain glycoproteins are densely O-glycosylated proteins with unique secondary structure that imparts a large influence on cellular environments. Here, the authors develop a technique to selectively enrich and characterize mucin-domain glycoproteins from cell lysate and patient biofluids.

LncRNA CBR3-AS1 promotes osteosarcoma progression through the network of miR-140-5p/DDX54-NUCKS1-mTOR signaling pathway

Long noncoding RNA (lncRNA) CBR3-AS1 (termed as CBR3-AS1) has been reported to be upregulated in several cancers including osteosarcoma. Its positive impact on the proliferation, migration, and invasion of osteosarcoma cells has been unveiled; nevertheless, whether it also affects the stemness and epithelial-mesenchymal transition (EMT) of osteosarcoma cells is unclear. The purpose for this study was to explore the effects of CBR3-AS1 on the stemness and EMT of osteosarcoma cells as well as its underlying mechanism. qRT-PCR and western blot were applied to detect target gene expression. Function assays were conducted to evaluate the effect of genes on the stemness and EMT of osteosarcoma cells. Mechanism assays were done to verify the association among different genes. In vivo assays were also performed. The obtained data showed that CBR3-AS1 demonstrated a high expression in osteosarcoma cells. CBR3-AS1 could promote stemness and EMT of osteosarcoma cells as well as osteosarcoma tumor growth. Mechanically, CBR3-AS1 sponged miR-140-5p and recruited DDX54 to upregulate NUCKS1, thus activating the mTOR signaling pathway. Furthermore, NUCKS1 could facilitate stemness and EMT of osteosarcoma cells. In summary, this study reveals that CBR3-AS1 exerts an oncogenic role in osteosarcoma through modulating the network of the miR-140-5p/DDX54-NUCKS1-mTOR signaling pathway.

Modelling the Tumor Microenvironment: Recapitulating Nano- and Micro-Scale Properties that Regulate Tumor Progression

Breast cancer remains a significant burden with 1 in 8 women affected and metastasis posing a significant challenge for patient survival. Disease progression involves remodeling of the extracellular matrix (ECM). In breast cancer, tissue stiffness increases owing to an increase in collagen production by recruited cancer-associated fibroblasts (CAFs). These stromal modifications are notable during primary tumor growth and have a dualistic action by creating a hard capsule to prevent penetration of anti-cancer therapies and forming a favorable environment for tumor progression. Remodeling of the tumor microenvironment immediately presented to cells can include changes in protein composition, concentration and structural arrangement and provides the first mechanical stimuli in the metastatic cascade. Not surprisingly, metastatic cancer cells possess the ability to mechanically adapt, and their adaptability ensures not only survival but successful invasion within altered environments. In the past decade, the importance of the microenvironment and its regulatory role in diseases have gained traction and this is evident in the shift from plastic culture to the development of novel biomaterials that mimic in vivo tissue. With these advances, elucidations can be made into how ECM remodeling and more specifically, altered cell-ECM adhesions, regulate tumor growth and cancer cell plasticity. Such enabling tools in mechanobiology will identify fundamental mechanisms in cancer progression that eventually help develop preventative and therapeutic treatment from a clinical perspective. This review will focus on current platforms engineered to mimic the micro and nano-properties of the tumor microenvironment and subsequent understanding of mechanically regulated pathways in cancer.

Resistance to Gemcitabine in Pancreatic Ductal Adenocarcinoma: A Physiopathologic and Pharmacologic Review

Pancreatic ductal adenocarcinoma (PDAC) is a very aggressive tumor with a poor prognosis and inadequate response to treatment. Many factors contribute to this therapeutic failure: lack of symptoms until the tumor reaches an advanced stage, leading to late diagnosis; early lymphatic and hematic spread; advanced age of patients; important development of a pro-tumoral and hyperfibrotic stroma; high genetic and metabolic heterogeneity; poor vascular supply; a highly acidic matrix; extreme hypoxia; and early development of resistance to the available therapeutic options. In most cases, the disease is silent for a long time, andwhen it does become symptomatic, it is too late for ablative surgery; this is one of the major reasons explaining the short survival associated with the disease. Even when surgery is possible, relapsesare frequent, andthe causes of this devastating picture are the low efficacy ofand early resistance to all known chemotherapeutic treatments. Thus, it is imperative to analyze the roots of this resistance in order to improve the benefits of therapy. PDAC chemoresistance is the final product of different, but to some extent, interconnected factors. Surgery, being the most adequate treatment for pancreatic cancer and the only one that in a few selected cases can achieve longer survival, is only possible in less than 20% of patients. Thus, the treatment burden relies on chemotherapy in mostcases. While the FOLFIRINOX scheme has a slightly longer overall survival, it also produces many more adverse eventsso that gemcitabine is still considered the first choice for treatment, especially in combination with other compounds/agents. This review discusses the multiple causes of gemcitabine resistance in PDAC.

TDP43 promotes stemness of breast cancer stem cells through CD44 variant splicing isoforms

Alternative splicing (AS) is a promising clinical target for cancer treatment at the post-transcriptional level. We previously identified a unique AS profile in triple-negative breast cancer (TNBC), which is regulated by the splicing regulator TAR DNA-binding protein-43 (TDP43), thus indicating the crucial role of TDP43 in heterogeneous TNBC. Cluster of differentiation 44 (CD44), a widely recognized marker for breast cancer stem cells (BCSCs), is extensively spliced into CD44 variant AS isoforms (CD44v) during the development of breast cancer. At present, however, the regulatory mechanism of CD44v is not fully understood. In the current study, we found that loss of TDP43 inhibits BCSC stemness by reducing the abundance of CD44v. In addition, serine-arginine-rich splicing factor 3 (SRSF3), another splicing factor and partner of TDP43, acts as an upstream regulator of TDP43 to maintain CD44v isoforms and thereafter BCSC stemness. Mechanistically, SRSF3 stabilizes the mRNA of TDP43 by inhibiting nonsense-mediated decay (NMD). These findings illustrate the important role of complicated regulatory networks formed by splicing factors in TNBC progression, thus providing potential therapeutic targets from an AS perspective.

Hyaluronic Acid: Known for Almost a Century, but Still in Vogue

Hyaluronic acid (HA) has a special position among glycosaminoglycans. As a major component of the extracellular matrix (ECM). This simple, unbranched polysaccharide is involved in the regulation of various biological cell processes, whether under physiological conditions or in cases of cell damage. This review summarizes the history of this molecule’s study, its distinctive metabolic pathway in the body, its unique properties, and current information regarding its interaction partners. Our main goal, however, is to intensively investigate whether this relatively simple polymer may find applications in protecting against ionizing radiation (IR) or for therapy in cases of radiation-induced damage. After exposure to IR, acute and belated damage develops in each tissue depending upon the dose received and the cellular composition of a given organ. A common feature of all organ damage is a distinct change in composition and structure of the ECM. In particular, the important role of HA was shown in lung tissue and the variability of this flexible molecule in the complex mechanism of radiation-induced lung injuries. Moreover, HA is also involved in intermediating cell behavior during morphogenesis and in tissue repair during inflammation, injury, and would healing. The possibility of using the HA polymer to affect or treat radiation tissue damage may point to the missing gaps in the responsible mechanisms in the onset of this disease. Therefore, in this article, we will also focus on obtaining answers from current knowledge and the results of studies as to whether hyaluronic acid can also find application in radiation science.

Cancer Stem Cell DNA Enabled Real-Time Genotyping with Self-Functionalized Quantum Superstructures-Overcoming the Barriers of Noninvasive cfDNA Cancer Diagnostics

Cancer diagnosis and determining its tissue of origin are crucial for clinical implementation of personalized medicine. Conventional diagnostic techniques such as imaging and tissue biopsy are unable to capture the dynamic tumor landscape. Although circulating tumor DNA (ctDNA) shows promise for diagnosis, the clinical relevance of ctDNA remains largely undetermined due to several biological and technical complexities. Here, cancer stem cell-ctDNA is used to overcome the biological complexities like the inability for molecular analysis of ctDNA and dependence on ctDNA concentration rather than the molecular profile. Ultrasensitive quantum superstructures overcome the technical complexities of trace-level detection and rapid diagnosis to detect ctDNA within its short half-life. Activation of multiple surface enhanced Raman scattering mechanisms of the quantum superstructures achieved a very high enhancement factor (1.35 × 10¹¹ ) and detection at ultralow concentration (10^-15 M) with very high reliability (RSD: 3-12%). Pilot validation with clinical plasma samples from an independent validation cohort achieved a diagnosis sensitivity of ≈95% and specificity of 83%. Quantum superstructures identified the tissue of origin with ≈75-86% sensitivity and ≈92-96% specificity. With large scale clinical validation, the technology can develop into a clinically useful liquid biopsy tool improving cancer diagnostics.

siRNA-induced CD44 knockdown suppresses the proliferation and invasion of colorectal cancer stem cells through inhibiting epithelial-mesenchymal transition

CD44 has shown prognostic values and promising therapeutic potential in multiple human cancers; however, the effects of CD44 silencing on biological behaviors of cancer stem cells (CSCs) have not been fully understood in colorectal cancer. To examine the contribution of siRNA‐induced knockdown of CD44 to the biological features of colorectal CSCs, colorectal CSCs HCT116‐CSCs were generated, and CD44 was knocked down in HCT116‐CSCs using siRNA. The proliferation, migration and invasion of HCT116‐CSCs were measured, and apoptosis and cell‐cycle analyses were performed. The sensitivity of HCT116‐CSCs to oxaliplatin was tested, and xenograft tumor growth assay was performed to examine the role of CD44 in HCT116‐CSCs tumorigenesis in vivo. In addition, the expression of epithelial–mesenchymal transition (EMT) markers E‐cadherin, N‐cadherin and vimentin was quantified. siRNA‐induced knockdown of CD44 was found to inhibit the proliferation, migration and invasion, induce apoptosis, promote cell‐cycle arrest at the G1/G0 phase and increase the sensitivity of HCT116‐CSCs to oxaliplatin in HCT116‐CSCs, and knockdown of CD44 suppressed in vivo tumorigenesis and intrapulmonary metastasis of HCT116‐CSCs. Moreover, silencing CD44 resulted in EMT inhibition. Our findings demonstrate that siRNA‐induced CD44 knockdown suppresses the proliferation, invasion and in vivo tumorigenesis and metastasis of colorectal CSCs by inhibiting EMT.

Identification of Key Pathways and Genes Related to Immunotherapy Resistance of LUAD Based on WGCNA Analysis

Immunotherapy resistance is a major barrier in the application of immune checkpoint inhibitors (ICI) in lung adenocarcinoma (LUAD) patients. Although recent studies have found several mechanisms and potential genes responsible for immunotherapy resistance, ways to solve this problem are still lacking. Tumor immune dysfunction and exclusion (TIDE) algorithm is a newly developed method to calculate potential regulators and indicators of ICI resistance. In this article, we combined TIDE and weighted gene co-expression network analysis (WGCNA) to screen potential modules and hub genes that are highly associated with immunotherapy resistance using the Cancer Genome Atlas (TCGA) dataset of LUAD patients. We identified 45 gene co-expression modules, and the pink module was most correlated with TIDE score and other immunosuppressive features. After considering the potential factors in immunotherapy resistance, we found that the pink module was also highly related to cancer stemness. Further analysis showed enriched immunosuppressive cells in the extracellular matrix (ECM), immunotherapy resistance indicators, and common cancer-related signaling pathways in the pink module. Seven hub genes in the pink module were shown to be significantly upregulated in tumor tissues compared with normal lung tissue, and were related to poor survival of LUAD patients. Among them, THY1 was the gene most associated with TIDE score, a gene highly related to suppressive immune states, and was shown to be strongly expressed in late-stage patients. Immunohistochemistry (IHC) results demonstrated that THY1 level was higher in the progressive disease (PD) group of LUAD patients receiving a PD-1 monoclonal antibody (mAb) and positively correlated with SOX9. Collectively, we identified that THY1 could be a critical biomarker in predicting ICI efficiency and a potential target for avoiding tumor immunotherapy resistance.

Functional and Molecular Characters of Cancer Stem Cells Through Development to Establishment

Cancer stem cells (CSCs) are small subpopulation sharing similar properties like normal stem such as self-renewal and differentiation potential to direct tumor growth. Last few years, scientists considered CSCs as the cause of phenotypic heterogeneity in diverse cancer types. Also, CSCs contribute to cancer metastasis and recurrence. The cellular and molecular regulators influence on the CSCs' phenotype changing their behaviors in different stages of cancer progression. CSC markers play significance roles in cancer diagnosis and characterization. We delineate the cross-talks between CSCs and the tumor microenvironment that supports their intrinsic properties including survival, stemness, quiescence and their cellular and molecular adaptation. An insight into the markers of CSCs specific to organs is described.

A xCT role in tumour-associated ferroptosis shed light on novel therapeutic options

Solute carrier family 7 member 11 (SLC7A11; also known as xCT), a key component of the cystine/glutamate antiporter, is essential for the maintenance of cellular redox status and the regulation of tumor-associated ferroptosis. Accumulating evidence has demonstrated that xCT overexpression, resulting from different oncogenic and tumor suppressor signaling, promotes tumor progression and multidrug resistance partially via suppressing ferroptosis. In addition, recent studies have highlighted the role of xCT in regulating the metabolic flexibility in cancer cells. In this review, the xCT activities in intracellular redox balance and in ferroptotic cell death have been summarized. Moreover, the role of xCT in promoting tumor development, drug resistance, and nutrient dependency in cancer cells has been explored. Finally, different therapeutic strategies, xCT-based, for anti-cancer treatments have been discussed.

Knockdown of zinc finger protein 267 suppresses diffuse large B-cell lymphoma progression, metastasis, and cancer stem cell properties

Zinc finger protein 267 (ZNF267) is a member of the Kruppel-like transcription factor family, which regulates various biological processes such as cell proliferation and differentiation. However, the biological significance of ZNF267 and its potential role in diffuse large B-cell lymphoma (DLBCL) remain to be documented. Experiments were herein conducted to study the role of ZNF267 in DLBCL. real-time quantitative reverse transcription PCR and Western blotting assays were conducted to detect the expression of ZNF267 in tissues and cells. Tissue microarray and bioinformatics analyses of public data were also done to detect the expression status and clinical significance of ZNF267. Functional cell experiments including CCK8 assay, colony formation assay, 5-ethynyl-2'-deoxyuridine (EDU) assay, terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) assay, transwell assay, and wound healing assay were conducted to study the effects of ZNF267 knockdown and overexpression on cell proliferation and mobility. Xenograft assay was also conducted to confirm the effects of ZNF267 knockdown in vivo. In the present study, we found ZNF267 was significantly upregulated in DLBCL and predicted a poor survival outcome based on the bioinformatics analysis. Functionally, the knockdown of ZNF267 resulted in less cell proliferation and mobility, whereas the overexpression led to enhanced cell proliferation and mobility. Animal experiments also confirmed that ZNF267 silence contributed to less tumor growth and less lung metastasis. Further analysis showed that ZFN267 knockdown resulted in decreased epithelial-mesenchymal transition (EMT) and cancer stem cell (CSC) properties. Our results suggest that ZNF267 is an oncogene in DLBCL and its silence could compromise the aggression of DLBCL, which makes ZNF267 a promising therapeutic target.

Eliminating Cancer Stem-Like Cells in Oral Cancer by Targeting Elementary Signaling Pathways

Oral cancer is a heterogeneous, aggressive, and complex entity. Current major treatment options for the disease are surgery, chemo, and/or radiotherapy either alone or in combination with each other. Each treatment method has its own limitations such as a significant journey with deformities and a protracted rehabilitation process leading to loss of self-esteem, loss of tolerance, and therapeutic side effects. Conventional therapies are frequently experienced with regimen resistance and recurrence attributed to the cancer stem cells (CSCs). Given that CSCs exert their tumorigenesis by affecting several cellular and molecular targets and pathways an improved understanding of CSCs' actions is required. Hence, more research is recommended to fully understand the fundamental mechanisms driving CSC-mediated treatment resistance. Despite the difficulties and disagreements surrounding the removal of CSCs from solid tumors, a great amount of knowledge has been derived from the characterization of CSCs. Various efforts have been made to identify the CSCs using several cell surface markers. In the current review, we will discuss numerous cell surface markers such as CD44, ALDH1, EPCAM, CD24, CD133, CD271, CD90, and Cripto-1 for identifying and isolating CSCs from primary oral squamous cell carcinoma (OSCC). Further, a spectrum of embryonic signaling pathways has been thought to be the main culprit of CSCs' active state in cancers, resulting in conventional therapeutic resistance. Hence, we discuss the functional and molecular bases of several signaling pathways such as the Wnt/beta;-catenin, Notch, Hedgehog, and Hippo pathways and their associations with disease aggressiveness. Moreover, numerous inhibitors targeting the above mentioned signaling pathways have already been identified and some of them are already undergoing clinical trials. Hence, the present review encapsulates the characterization and effectiveness of the prospective potential targeted therapies for eradicating CSCs in oral cancers.

Reduction in O-glycome induces differentially glycosylated CD44 to promote stemness and metastasis in pancreatic cancer

Aberrant protein glycosylation has been shown to have a significant contribution in aggressive cancer, including pancreatic cancer (PC). Emerging evidence has implicated the involvement of cancer stem cells (CSCs) in PC aggressiveness; however, the contribution of glycosylation on self-renewal properties and maintenance of CSC is understudied. Here, using several in vitro and in vivo models lacking C1GALT1 expression, we identified the role of aberrant O-glycosylation in stemness properties and aggressive PC metastasis. A loss in C1GALT1 was found to result in the truncation of O-glycosylation on several glycoproteins with an enrichment of Tn carbohydrate antigen. Mapping of Tn-bearing glycoproteins in C1GALT1 KO cells identified significant Tn enrichment on CSC glycoprotein CD44. Notably, a loss of C1GALT1 in PC cells was found to enhance CSC features (side population-SP, ALDH1+, and tumorspheres) and self-renewal markers NANOG, SOX9, and KLF4. Furthermore, a loss of CD44 in existing C1GALT1 KO cells decreased NANOG expression and CSC features. We determined that O-glycosylation of CD44 activates ERK/NF-kB signaling, which results in increased NANOG expression in PC cells that facilitated the alteration of CSC features, suggesting that NANOG is essential for PC stemness. Finally, we identified that loss of C1GALT1 expression was found to augment tumorigenic and metastatic potential, while an additional loss of CD44 in these cells reversed the effects. Overall, our results identified that truncation of O-glycans on CD44 increases NANOG activation that mediates increased CSC activation.

BTB and CNC homology 1 (Bach1) induces lung cancer stem cell phenotypes by stimulating CD44 expression

BACKGROUND

Growing evidence suggests that cancer stem cells (CSCs) are responsible for cancer initiation in tumors. Bach1 has been identified to contribute to several tumor progression, including lung cancer. The role of Bach1 in CSCs remains poorly known. Therefore, the function of Bach1 on lung CSCs was focused currently.

METHODS

The expression of Bach1, CD133, CD44, Sox2, Nanog and Oct4 mRNA was assessed using Real-Time Quantitative Reverse Transcription PCR (RT-qPCR). Protein expression of Bach1, CD133, CD44, Sox2, Nanog, Oct4, p53, BCL2, BAX, p-p38, p-AKT1, c-Fos and c-Jun protein was analyzed by western blotting. 5-ethynyl-29-deoxyuridine (EdU), colony formation, Flow cytometry analysis and transwell invasion assay were carried out to analyze lung cancer cell proliferation, apoptosis and invasion respectively. Tumor sphere formation assay was utilized to evaluate spheroid capacity. Flow cytometry analysis was carried out to isolate CD133 or CD44 positive lung cancer cells. The relationship between Bach1 and CD44 was verified using ChIP-qPCR and dual-luciferase reporter assay. Xenograft tumor tissues were collected for hematoxylin and eosin (HE) staining and IHC analysis to evaluate histology and Ki-67.

RESULTS

The ratio of CD44 + CSCs from A549 and SPC-A1 cells were significantly enriched. Tumor growth of CD44 + CSCs was obviously suppressed in vivo compared to CD44- CSCs. Bach1 expression was obviously increased in CD44 + CSCs. Then, via using the in vitro experiment, it was observed that CSCs proliferation and invasion were greatly reduced by the down-regulation of Bach1 while cell apoptosis was triggered by knockdown of Bach1. Loss of Bach1 was able to repress tumor-sphere formation and tumor-initiating CSC markers. A repression of CSCs growth and metastasis of shRNA-Bach1 was confirmed using xenograft models and caudal vein injection. The direct interaction between Bach1 and CD44 was confirmed by ChIP-qPCR and dual-luciferase reporter assay. Furthermore, mitogen-activated protein kinases (MAPK) signaling pathway was selected and we proved the effects of Bach1 on lung CSCs were associated with the activation of the MAPK pathway. As manifested, loss of Bach1 was able to repress p-p38, p-AKT1, c-Fos, c-Jun protein levels in lung CSCs. Inhibition of MAPK signaling remarkably restrained lung CSCs growth and CSCs properties induced by Bach1 overexpression.

CONCLUSION

In summary, we imply that Bach1 demonstrates great potential for the treatment of lung cancer metastasis and recurrence via activating CD44 and MPAK signaling.

Targeting Cancer Stem Cell Markers or Pathways: A Potential Therapeutic Strategy for Oral Cancer Treatment

Cancer stem cells (CSCs) are a small subset of cancer cells with stem cell-like properties, self-renewal potential, and differentiation capacity into multiple cell types. Critical genetic alterations or aberrantly activated signaling pathways associated with drug resistance and recurrence have been observed in multiple types of CSCs. In this context, CSCs are considered to be responsible for tumor initiation, growth, progression, therapeutic resistance, and metastasis. Therefore, to effectively eradicate CSCs, tremendous efforts have been devoted to identify specific target molecules that play a critical role in regulating their distinct functions and to develop novel therapeutics, such as proteins, monoclonal antibodies, selective small molecule inhibitors, and small antisense RNA (asRNA) drugs. Similar to other CSC types, oral CSCs can be characterized by certain pluripotency-associated markers, and oral CSCs can also survive and form 3D tumor spheres in suspension culture conditions. These oral CSC-targeting therapeutics selectively suppress specific surface markers or key signaling components and subsequently inhibit the stem-like properties of oral CSCs. A large number of new therapeutic candidates have been tested, and some products are currently in the pre-clinical or clinical development phase. In the present study, we review new oral CSC-targeted therapeutic strategies and discuss the various specific CSC surface markers and key signaling components involved in the stem-like properties, growth, drug resistance, and tumorigenicity of oral CSCs.

Exosome CTLA-4 Regulates PTEN/CD44 Signal Pathway in Spleen Deficiency Internal Environment to Promote Invasion and Metastasis of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common primary cancers, and its pathogenesis is complicated and difficult to screen. Currently, there is no effective treatment. In traditional Chinese medicine, a large proportion of patients with HCC have been diagnosed with spleen deficiency (SD) syndrome and treated with tonifying traditional Chinese medicine, which has significant clinical efficacy. However, the role and molecular mechanism of SD in HCC remain unclear. In this study, 40 mice were randomly divided into four groups: control, SD, HCC, and SD-HCC groups. The liver cancer model of SD was established by reserpine induction and orthotopic transplantation. The effects of SD on the proliferation, apoptosis, invasion, and metastasis of HCC cells were studied by cell proliferation, cell apoptosis, cell scratch, and transwell assay. We found that compared with the HCC group, the protein expressions of cytotoxic T lymphocyte antigen 4 (CTLA-4), programmed cell death protein 1 (PD-1), phosphatase and tensin homolog (PTEN), and AKT (also known as protein kinase B or PKB) in the exosomes of the SD-HCC group were upregulated. In addition, the metastases and self-renewal of exosomes in the SD-HCC group were more aggressive than those in the HCC group, which could be partially reversed with the addition of CTLA-4 inhibitors. Further studies showed that in the internal environment of SD, CTLA-4 promoted tumor invasion and metastasis by regulating the PTEN/CD44 pathway. In conclusion, our findings suggest that during SD in the internal environment, exosome CTLA-4 regulates the PTEN/CD44 signal pathway to promote the proliferation, self-renewal, and metastasis of liver cancer.

Wogonoside inhibits TNF receptor-associated factor 6 (TRAF6) mediated-tumor microenvironment and prognosis of pancreatic cancer

Background

Pancreatic cancer (PC) is one of the worst prognostic cancers. Here, we probed the anti-cancer activity of wogonoside (Wog), a flavonoid isolated from Scutellaria baicalensis Georgi, on PC, as well as potential molecular mechanism.

Methods

Following Wog stimulation, the viability, proliferation, apoptosis, stem cell-like transition, and mesenchymal transition were detected in PC cells. Bioinformatics analysis was used to identify possible signaling pathways involved in the anti-PC activity of Wog. Tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) was overexpressed and TRAF6 activator IL-1β was used in PC cells to confirm whether Wog exerted anti-PC activity via modulating TRAF6. In vivo, an experiment was conducted to further confirm our supposition.

Results

Wog inhibited PC cell proliferation, promoted cell apoptosis, limited PC cell stem cell-like transition and mesenchymal transition. TNF signaling pathway was activated in PC. Besides, Wog inactivated TRAF6/nuclear factor-kappa B (NF-κB)/p65 pathway in PC cells. TRAF6, vascular cell adhesion molecule-1 (VCAM1), CD44, and matrix metalloproteinase 14 (MMP14) expressions were upregulated in PC tissues and negatively correlated with PC survival and prognosis. Finally, Wog suppressed TRAF6 overexpression-induced PC cell stem cell-like transition and mesenchymal transition in vitro and tumor growth in vivo.

Conclusions

Wog exerted anti-cancer activity on PC and suppressed the TRAF6 mediated-tumor microenvironment of PC, thereby regulating PC's prognosis.

The Role of Cellular Prion Protein in Cancer Biology: A Potential Therapeutic Target

Prion protein has two isoforms including cellular prion protein (PrP^C) and scrapie prion protein (PrP^Sc). PrP^Sc is the pathological aggregated form of prion protein and it plays an important role in neurodegenerative diseases. PrP^C is a glycosylphosphatidylinositol (GPI)-anchored protein that can attach to a membrane. Its expression begins at embryogenesis and reaches the highest level in adulthood. PrP^C is expressed in the neurons of the nervous system as well as other peripheral organs. Studies in recent years have disclosed the involvement of PrP^C in various aspects of cancer biology. In this review, we provide an overview of the current understanding of the roles of PrP^C in proliferation, cell survival, invasion/metastasis, and stem cells of cancer cells, as well as its role as a potential therapeutic target.

Targeted delivery of doxorubicin through CD44 aptamer to cancer cells

Aim: The current investigation is focused on the targeted delivery of doxorubicin through CD44 aptamer-mediated active targeting to the human breast cancer cells. Methods: CD44 aptamer-doxorubicin (Apt-Dox) conjugates were developed by incubating different molar ratios of aptamer and doxorubicin. Cytotoxicity, selective intracellular accumulation and uptake of the Apt-Dox conjugates were analyzed to evaluate the efficacy of Apt-Dox conjugates. Results: Dox was efficiently conjugated with aptamer at 1:2 Apt-Dox molar ratios. Apt-Dox conjugate significantly inhibited the proliferation of CD44-overexpressing breast cancer cells, whereas negligible inhibition of cell proliferation was found in the control cells. Apt-Dox conjugate selectively internalized and accumulated in CD44-overexpressing cells. Conclusion: Apt-Dox conjugate selectively delivers doxorubicin to CD44-expressing cancer cells, thereby inhibiting selective cell proliferation and enhancing the targeted therapy.

Stem Cells and Cancer Stem Cells: The Jekyll and Hyde Scenario and Their Implications in Stem Cell Therapy

"Jekyll and Hyde" refers to persons with an unpredictably dual personality, who are battling between good and evil within themselves In this regard, even cells consist of good and evil counterparts. Normal stem cells (NSCs) and cancer stem cells (CSCs) are two types of cells that share some similar characteristics but have distinct functions that play a major role in physiological and pathophysiological development. In reality, NSCs such as the adult and embryonic stem cells, are the good cells and the ultimate treatment used in cell therapy. CSCs are the corrupted cells that are a subpopulation of cancer cells within the cancer microenvironment that grow into a massive tumour or malignancy that needs to be treated. Hence, understanding the connection between NSCs and CSCs is important not just in cancer development but also in their therapeutic implication, which is the focus of this review.

Reduced DAPK1 Expression Promotes Stem Cell-Like Characteristics of Prostate Cancer Cells by Activating ZEB1 via Hippo/YAP Signaling Pathway

Prostate cancer (PCa) is a malignant tumor that originates in the male genitourinary system. Downregulation of death-associated protein kinase 1 (DAPK1) is closely related to PCa. Little is known about the functional role of DAPK1 in regulating cancer stem cell (CSC)-like characteristics of PCa cells, and we have conducted research on this topic. Compared with tumor-adjacent normal tissues, DAPK1 was severely downregulated in tumor tissues of PCa patients. DAPK1 expression was also reduced in PCa cell lines with respect to that in normal prostate cells. Moreover, we sorted PCa-CSCs (PCa-CD133⁺ cells) from PCa cells. PCa-CD133⁺ cells also exhibited a reduced DAPK1 level and elevated levels of stem cell markers (CD44, OCT4, and SOX2). DAPK1 knockdown promoted sphere formation and enhanced the proportions of PCa-CD133⁺/PCa-CD133^- cells. Inhibition of DAPK1 also accelerated migration and invasion of PCa-CD133⁺ cells. In addition, DAPK1 interacted with zinc finger E-box-binding homeobox-1 (ZEB1) and repressed ZEB1 expression in PCa-CD133⁺ cells. DAPK1 suppressed Hippo/YAP signaling pathway by interacting with ZEB1. Finally, we generated a tumor xenograft model to verify the effect of PCa-CD133⁺ cells following DAPK1 overexpression on tumor growth of PCa. DAPK1 overexpression inhibited tumor growth of PCa and repressed the expression of ZEB1, YAP, and TAZ in the tumor tissues of PCa mice. In conclusion, reduced DAPK1 expression promoted stem cell-like characteristics of PCa cells through activating ZEB1 via Hippo/YAP signaling pathway. Taken together, this work sheds lights on the potential of DAPK1 as a target for PCa therapeutics from bench to clinic.

Nanotherapeutic approach to tackle chemotherapeutic resistance of cancer stem cells

Estimates indicate that cancer will become the leading cause of mortality worldwide in the future. Tumorigenesis is a complex process that involves self-sufficiency in signs of growth, insensitivity to anti-growth signals, prevention of apoptosis, unlimited replication, sustained angiogenesis, tissue invasion, and metastasis. Cancer stem cells (CSCs) have an important role in tumor development and resistance. Here we will approach phenotypic plasticity capacity, highly efficient DNA repair systems, anti-apoptotic machinery, sustained stemness features, interaction with the tumor microenvironment, and Notch, Wnt, and Hedgehog signaling pathways. The researches about CSCs as a target in cancer treatment has been growing. Many different options have pointed beneficial results, such as pathways and CSC-surface markers targeting. Besides its limitations, nanotherapeutics have emerged as a potential strategy in this context since they aim to improve pharmacokinetics, biodistribution, and reduce the side effects observed in traditional treatments. Nanoparticles have been studied in this field, mostly for drug delivery and a multitherapy approach. Another widely researched approaches in this area are related to heat therapy, such as photothermal therapy, photodynamic therapy and magnetic hyperthermia, besides molecular targeting. This review will contemplate the most relevant studies that have shown the effects of nanotherapeutics. In conclusion, although the studies analyzed are mostly preclinical, we believe that there is strong evidence that nanoparticles can increase the chances of a better prognosis to cancer in the future. It is also essential to transpose these findings to the clinic to confirm and better understand the role of nanotherapeutics in this context.