Recapitulating thyroid cancer histotypes through engineering embryonic stem cells

Thyroid carcinoma (TC) is the most common malignancy of endocrine organs. The cell subpopulation in the lineage hierarchy that serves as cell of origin for the different TC histotypes is unknown. Human embryonic stem cells (hESCs) with appropriate in vitro stimulation undergo sequential differentiation into thyroid progenitor cells (TPCs-day 22), which maturate into thyrocytes (day 30). Here, we create follicular cell-derived TCs of all the different histotypes based on specific genomic alterations delivered by CRISPR-Cas9 in hESC-derived TPCs. Specifically, TPCs harboring BRAF^V600E or NRAS^Q61R mutations generate papillary or follicular TC, respectively, whereas addition of TP53^R248Q generate undifferentiated TCs. Of note, TCs arise by engineering TPCs, whereas mature thyrocytes have a very limited tumorigenic capacity. The same mutations result in teratocarcinomas when delivered in early differentiating hESCs. Tissue Inhibitor of Metalloproteinase 1 (TIMP1)/Matrix metallopeptidase 9 (MMP9)/Cluster of differentiation 44 (CD44) ternary complex, in cooperation with Kisspeptin receptor (KISS1R), is involved in TC initiation and progression. Increasing radioiodine uptake, KISS1R and TIMP1 targeting may represent a therapeutic adjuvant option for undifferentiated TCs.

Correlative Raman-Electron-Light (CREL) Microscopy Analysis of Lipid Droplets in Melanoma Cancer Stem Cells

Among all neoplasms, melanoma is characterized by a very high percentage of cancer stem cells (CSCs). Several markers have been proposed for their identification, and lipid droplets (LDs) are among them. Different techniques are used for their characterization such as mass spectrometry, imaging techniques, and vibrational spectroscopies. Some emerging experimental approaches for the study of LDs are represented by correlative light-electron microscopy and by correlative Raman imaging-scanning electron microscopy (SEM). Based on these scientific approaches, we developed a novel methodology (CREL) by combining Raman micro-spectroscopy, confocal fluorescence microscopy, and SEM coupled with an energy-dispersive X-ray spectroscopy module. This procedure correlated cellular morphology, chemical properties, and spatial distribution from the same region of interest, and in this work, we presented the application of CREL for the analysis of LDs within patient-derived melanoma CSCs (MCSCs).

BCL-XL inhibition induces an FGFR4-mediated rescue response in colorectal cancer

The heterogeneous therapy response observed in colorectal cancer is in part due to cancer stem cells (CSCs) that resist chemotherapeutic insults. The anti-apoptotic protein BCL-XL plays a critical role in protecting CSCs from cell death, where its inhibition with high doses of BH3 mimetics can induce apoptosis. Here, we screen a compound library for synergy with low-dose BCL-XL inhibitor A-1155463 to identify pathways that regulate sensitivity to BCL-XL inhibition and reveal that fibroblast growth factor receptor (FGFR)4 inhibition effectively sensitizes to A-1155463 both in vitro and in vivo. Mechanistically, we identify a rescue response that is activated upon BCL-XL inhibition and leads to rapid FGF2 secretion and subsequent FGFR4-mediated post-translational stabilization of MCL-1. FGFR4 inhibition prevents MCL-1 upregulation and thereby sensitizes CSCs to BCL-XL inhibition. Altogether, our findings suggest a cell transferable induction of a FGF2/FGFR4 rescue response in CRC that is induced upon BCL-XL inhibition and leads to MCL-1 upregulation.

Dual Inhibition of Myc Transcription and PI3K Activity Effectively Targets Colorectal Cancer Stem Cells

Simple Summary

Compelling evidence has shown that cancer stem cells (CSCs) are responsible for high resistance to conventional anti-cancer therapies. Here, we demonstrate that the tumor microenvironment protects CR-CSCs from EGFR/HER2, BRAF and PI3K targeting, promoting CD44v6 and Myc expression. Alternatively, as a substitution for HER2 and BRAF, the Myc transcription inhibitor can overcome the protective effects of microenvironmental cytokines, impairing the survival of CR-CSCs. These data highlight the targeting of Myc and PI3K activity as a novel therapeutic strategy against advanced colorectal cancer.

Abstract

Despite advances in the curative approach, the survival rate of advanced colorectal cancer (CRC) patients is still poor, which is likely due to the emergence of cancer cell clones resistant to the available therapeutic options. We have already shown that CD44v6-positive CRC stem cells (CR-CSCs) are refractory toward standard anti-tumor therapeutic agents due to the activation of the PI3K pathway together with high HER2 expression levels. Tumor microenvironmental cytokines confer resistance to CR-CSCs against HER2/PI3K targeting by enhancing activation of the MAPK pathway. Here, we show that the CSC compartment, spared by BRAF inhibitor-based targeted therapy, is associated with increased expression levels of CD44v6 and Myc and retains boosted clonogenic activity along with residual tumorigenic potential. Inhibition of Myc transcription, downstream of the MAPK cascade components, and PI3K pathway activity was able to overcome the protective effects of microenvironmental cytokines, affecting the survival and the clonogenic activity of CR-CSCs, regardless of their mutational background. Likewise, the double targeting induced stabilization of mouse tumor avatars. Altogether, these data outline the rationale for dual kinase targeting of CR-CSCs to prevent their adaptive response, which would lead to disease progression.

PI3K-driven HER2 expression is a potential therapeutic target in colorectal cancer stem cells

OBJECTIVE

Cancer stem cells are responsible for tumour spreading and relapse. Human epidermal growth factor receptor 2 (HER2) expression is a negative prognostic factor in colorectal cancer (CRC) and a potential target in tumours carrying the gene amplification. Our aim was to define the expression of HER2 in colorectal cancer stem cells (CR-CSCs) and its possible role as therapeutic target in CRC resistant to anti- epidermal growth factor receptor (EGFR) therapy.

DESIGN

A collection of primary sphere cell cultures obtained from 60 CRC specimens was used to generate CR-CSC mouse avatars to preclinically validate therapeutic options. We also made use of the ChIP-seq analysis for transcriptional evaluation of HER2 activation and global RNA-seq to identify the mechanisms underlying therapy resistance.

RESULTS

Here we show that in CD44v6-positive CR-CSCs, high HER2 expression levels are associated with an activation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, which promotes the acetylation at the regulatory elements of the Erbb2 gene. HER2 targeting in combination with phosphatidylinositol 3-kinase (PI3K) and mitogen-activated protein kinase kinase (MEK) inhibitors induces CR-CSC death and regression of tumour xenografts, including those carrying Kras and Pik3ca mutation. Requirement for the triple targeting is due to the presence of cancer-associated fibroblasts, which release cytokines able to confer CR-CSC resistance to PI3K/AKT inhibitors. In contrast, targeting of PI3K/AKT as monotherapy is sufficient to kill liver-disseminating CR-CSCs in a model of adjuvant therapy.

CONCLUSIONS

While PI3K targeting kills liver-colonising CR-CSCs, the concomitant inhibition of PI3K, HER2 and MEK is required to induce regression of tumours resistant to anti-EGFR therapies. These data may provide a rationale for designing clinical trials in the adjuvant and metastatic setting.

FACS-based protocol to assess cytotoxicity and clonogenic potential of colorectal cancer stem cells using a Wnt/β-catenin signaling pathway reporter

Cancer stem cells (CSCs) play a key role in tumor initiation and progression. A real-time tool to evaluate the activation of CSC-specific signaling pathways is crucial for the study of this cancer cell subset. Here, we present a protocol to monitor, in vitro, the activation of Wnt/β-catenin signaling pathway, which is considered a functional biomarker for colorectal CSCs (CR-CSCs). This flow-cytometry-based protocol allows it to isolate CR-CSCs and to evaluate their cytotoxicity upon anti-tumor treatments. For complete details on the use and execution of this protocol, please refer to Di Franco et al. (2021).

Adipose stromal cells promote the transition of colorectal cancer cells toward a mesenchymal-like phenotype

Colon cancer progression is among the risks that increase with obesity. We have recently unveiled the molecular mechanism by which adipose tissue-released molecules, HGF and IL-6, make colorectal cancer (CRC) cells acquiring mesenchymal traits. Targeting of adipose-derived factors abrogate the metastatic potential of CRC stem cells (CR-CSCs) in obese patients.

Messing Up the Cancer Stem Cell Chemoresistance Mechanisms Supported by Tumor Microenvironment

Despite the recent advances in cancer patient management and in the development of targeted therapies, systemic chemotherapy is currently used as a first-line treatment for many cancer types. After an initial partial response, patients become refractory to standard therapy fostering rapid tumor progression. Compelling evidence highlights that the resistance to chemotherapeutic regimens is a peculiarity of a subpopulation of cancer cells within tumor mass, known as cancer stem cells (CSCs). This cellular compartment is endowed with tumor-initiating and metastasis formation capabilities. CSC chemoresistance is sustained by a plethora of grow factors and cytokines released by neighboring tumor microenvironment (TME), which is mainly composed by adipocytes, cancer-associated fibroblasts (CAFs), immune and endothelial cells. TME strengthens CSC refractoriness to standard and targeted therapies by enhancing survival signaling pathways, DNA repair machinery, expression of drug efflux transporters and anti-apoptotic proteins. In the last years many efforts have been made to understand CSC-TME crosstalk and develop therapeutic strategy halting this interplay. Here, we report the combinatorial approaches, which perturb the interaction network between CSCs and the different component of TME.

CHK1 inhibitor sensitizes resistant colorectal cancer stem cells to nortopsentin

Limited therapeutic options are available for advanced colorectal cancer (CRC). Herein, we report that exposure to a neo-synthetic bis(indolyl)thiazole alkaloid analog, nortopsentin 234 (NORA234), leads to an initial reduction of proliferative and clonogenic potential of CRC sphere cells (CR-CSphCs), followed by an adaptive response selecting the CR-CSphC-resistant compartment. Cells spared by the treatment with NORA234 express high levels of CD44v6, associated with a constitutive activation of Wnt pathway. In CR-CSphC-based organoids, NORA234 causes a genotoxic stress paralleled by G2-M cell cycle arrest and activation of CHK1, driving the DNA damage repair of CR-CSphCs, regardless of the mutational background, microsatellite stability, and consensus molecular subtype. Synergistic combination of NORA234 and CHK1 (rabusertib) targeting is synthetic lethal inducing death of both CD44v6-negative and CD44v6-positive CRC stem cell fractions, aside from Wnt pathway activity. These data could provide a rational basis to develop an effective strategy for the treatment of patients with CRC.

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CR-CSCs acquire a long-term resistance to the NORA234 treatment

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Replicative and genotoxic stress induces the activation of CHK1

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Adaptive response to NORA234 is associated with high expression levels of CHK1

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NORA234 together with targeting of CHK1 leads to depletion of CR-CSC compartment

Magnetic Nanoparticle-Based Hyperthermia Mediates Drug Delivery and Impairs the Tumorigenic Capacity of Quiescent Colorectal Cancer Stem Cells

Cancer stem cells (CSCs) are the tumor cell subpopulation responsible for resistance to chemotherapy, tumor recurrence, and metastasis. An efficient therapy must act on low proliferating quiescent-CSCs (q-CSCs). We here investigate the effect of magnetic hyperthermia (MHT) in combination with local chemotherapy as a dual therapy to inhibit patient-derived colorectal qCR-CSCs. We apply iron oxide nanocubes as MHT heat mediators, coated with a thermoresponsive polymer (TR-Cubes) and loaded with DOXO (TR-DOXO) as a chemotherapeutic agent. The thermoresponsive polymer releases DOXO only at a temperature above 44 °C. In colony-forming assays, the cells exposed to TR-Cubes with MHT reveal that qCR-CSCs struggle to survive the heat damage and, with a due delay, restart the division of dormant cells. The eradication of qCR-CSCs with a complete stop of the colony formation was achieved only with TR-DOXO when exposed to MHT. The in vivo tumor formation study confirms the combined effects of MHT with heat-mediated drug release: only the group of animals that received the CR-CSCs pretreated, in vitro, with TR-DOXO and MHT lacked the formation of tumor even after several months. For DOXO-resistant CR-CSCs cells, the same results were shown, in vitro, when choosing the drug oxaliplatin rather than DOXO and applying MHT. These findings emphasize the potential of our nanoplatforms as an effective patient-personalized cancer treatment against qCR-CSCs.

Pharmacological targeting of the novel β-catenin chromatin-associated kinase p38α in colorectal cancer stem cell tumorspheres and organoids

The prognosis of locally advanced colorectal cancer (CRC) is currently unsatisfactory. This is mainly due to drug resistance, recurrence, and subsequent metastatic dissemination, which are sustained by the cancer stem cell (CSC) population. The main driver of the CSC gene expression program is Wnt signaling, and previous reports indicate that Wnt3a can activate p38 MAPK. Besides, p38 was shown to feed into the canonical Wnt/β-catenin pathway. Here we show that patient-derived locally advanced CRC stem cells (CRC-SCs) are characterized by increased expression of p38α and are "addicted" to its kinase activity. Of note, we found that stage III CRC patients with high p38α levels display reduced disease-free and progression-free survival. Extensive molecular analysis in patient-derived CRC-SC tumorspheres and APCMin/+ mice intestinal organoids revealed that p38α acts as a β-catenin chromatin-associated kinase required for the regulation of a signaling platform involved in tumor proliferation, metastatic dissemination, and chemoresistance in these CRC model systems. In particular, the p38α kinase inhibitor ralimetinib, which has already entered clinical trials, promoted sensitization of patient-derived CRC-SCs to chemotherapeutic agents commonly used for CRC treatment and showed a synthetic lethality effect when used in combination with the MEK1 inhibitor trametinib. Taken together, these results suggest that p38α may be targeted in CSCs to devise new personalized CRC treatment strategies.

ROS and Lipid Droplet accumulation induced by high glucose exposure in healthy colon and Colorectal Cancer Stem Cells

Lipid Droplets (LDs) are emerging as crucial players in colon cancer development and maintenance. Their expression has been associated with high tumorigenicity in Cancer Stem Cells (CSCs), so that they have been proposed as a new functional marker in Colorectal Cancer Stem Cells (CR-CSCs). They are also indirectly involved in the modulation of the tumor microenvironment through the production of pro-inflammatory molecules. There is growing evidence that a possible connection between metabolic alterations and malignant transformation exists, although the effects of nutrients, primarily glucose, on the CSC behavior are still mostly unexplored. Glucose is an essential fuel for cancer cells, and the connections with LDs in the healthy and CSC populations merit to be more deeply investigated. Here, we showed that a high glucose concentration activated the PI3K/AKT pathway and increased the expression of CD133 and CD44v6 CSC markers. Additionally, glucose was responsible for the increased amount of Reactive Oxygen Species (ROS) and LDs in both healthy and CR-CSC samples. We also investigated the gene modulations following the HG treatment and found out that the healthy cell gene profile was the most affected. Lastly, Atorvastatin, a lipid-lowering drug, induced the highest mortality on CR-CSCs without affecting the healthy counterpart.

DNA methylation of shelf, shore and open sea CpG positions distinguish high microsatellite instability from low or stable microsatellite status colon cancer stem cells

Aim: To investigate the genome-wide methylation of genetically characterized colorectal cancer stem cell (CR-CSC) lines. Materials & methods: Eight CR-CSC lines were isolated from primary colorectal cancer (CRC) tissues, cultured and characterized for aneuploidy, mutational status of CRC-related genes and microsatellite instability (MSI). Genome-wide DNA methylation was assessed by MethylationEPIC microarray. Results: We describe a distinctive methylation pattern that is maintained following in vivo passages in immune-compromised mice. We identified an epigenetic CR-CSC signature associated with MSI. We noticed that the preponderance of the differentially methylated positions do not reside at CpG islands, but spread to shelf and open sea regions. Conclusion: Given that CRCs with MSI-high status have a lower metastatic potential, the identification of a MSI-related methylation signature could provide new insights and possible targets into metastatic CRC.

Cancer-associated fibroblasts as abettors of tumor progression at the crossroads of EMT and therapy resistance

In the last decades, the role of the microenvironment in tumor progression and therapeutic outcome has gained increasing attention. Cancer-associated fibroblasts (CAFs) have emerged as key players among stromal cells, owing to their abundance in most solid tumors and their diverse tumor-restraining/promoting roles. The interplay between tumor cells and neighboring CAFs takes place by both paracrine signals (cytokines, exosomes and metabolites) or by the multifaceted functions of the surrounding extracellular matrix. Here, we dissect the most recent identified mechanisms underlying CAF-mediated control of tumor progression and therapy resistance, which include induction of the epithelial-to-mesenchymal transition (EMT), activation of survival pathways or stemness-related programs and metabolic reprogramming in tumor cells. Importantly, the recently unveiled heterogeneity in CAFs claims tailored therapeutic efforts aimed at eradicating the specific subset facilitating tumor progression, therapy resistance and relapse. However, despite the large amount of pre-clinical data, much effort is still needed to translate CAF-directed anti-cancer strategies from the bench to the clinic.

CHK1-targeted therapy to deplete DNA replication-stressed, p53-deficient, hyperdiploid colorectal cancer stem cells

OBJECTIVE

Cancer stem cells (CSCs) are responsible for tumour formation and spreading, and their targeting is required for tumour eradication. There are limited therapeutic options for advanced colorectal cancer (CRC), particularly for tumours carrying RAS-activating mutations. The aim of this study was to identify novel CSC-targeting strategies.

DESIGN

To discover potential therapeutics to be clinically investigated as single agent, we performed a screening with a panel of FDA-approved or investigational drugs on primary CRC cells enriched for CSCs (CRC-SCs) isolated from 27 patients. Candidate predictive biomarkers of efficacy were identified by integrating genomic, reverse-phase protein microarray (RPPA) and cytogenetic analyses, and validated by immunostainings. DNA replication stress (RS) was increased by employing DNA replication-perturbing or polyploidising agents.

RESULTS

The drug-library screening led to the identification of LY2606368 as a potent anti-CSC agent acting in vitro and in vivo in tumour cells from a considerable number of patients (∼36%). By inhibiting checkpoint kinase (CHK)1, LY2606368 affected DNA replication in most CRC-SCs, including RAS-mutated ones, forcing them into premature, lethal mitoses. Parallel genomic, RPPA and cytogenetic analyses indicated that CRC-SCs sensitive to LY2606368 displayed signs of ongoing RS response, including the phosphorylation of RPA32 and ataxia telangiectasia mutated serine/threonine kinase (ATM). This was associated with mutation(s) in TP53 and hyperdiploidy, and made these CRC-SCs exquisitely dependent on CHK1 function. Accordingly, experimental increase of RS sensitised resistant CRC-SCs to LY2606368.

CONCLUSIONS

LY2606368 selectively eliminates replication-stressed, p53-deficient and hyperdiploid CRC-SCs independently of RAS mutational status. These results provide a strong rationale for biomarker-driven clinical trials with LY2606368 in patients with CRC.

Combined platelet-rich plasma and lipofilling treatment provides great improvement in facial skin-induced lesion regeneration for scleroderma patients

Background

The use of stem cells, including mesenchymal stem cells (MSCs), for regenerative medicine is gaining interest for the clinical benefits so far obtained in patients. This study investigates the use of adipose autologous tissue in combination with platelet-rich plasma (PRP) to improve the clinical outcome of patients affected by systemic sclerosis (SSc).

Methods

Adipose-derived mesenchymal stem cells (AD-MSCs) and PRPs were purified from healthy donors and SSc patients. The multilineage differentiation potential of AD-MSCs and their genotypic–phenotypic features were investigated. A cytokine production profile was evaluated on AD-MSCs and PRPs from both healthy subjects and SSc patients. The adipose tissue-derived cell fraction, the so-called stromal vascular fraction (SVF), was coinjected with PRP in the perioral area of SSc patients.

Results

Histopathological and phenotypical analysis of adipose tissue from SSc patients revealed a disorganization of its distinct architecture coupled with an altered cell composition. Although AD-MSCs derived from SSc patients showed high multipotency, they failed to sustain a terminally differentiated progeny. Furthermore, SVFs derived from SSc patients differed from healthy donors in their MSC-like traits coupled with an aberrant cytokine production profile. Finally, the administration of PRP in combination with autologous SVF improved buccal’s rhyme, skin elasticity and vascularization for all of the SSc patients enrolled in this study.

Conclusions

This innovative regenerative therapy could be exploited for the treatment of chronic connective tissue diseases, including SSc.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0690-3) contains supplementary material, which is available to authorized users.

Role of Type I and II Interferons in Colorectal Cancer and Melanoma

Cancer can be considered an aberrant organ with a hierarchical composition of different cell populations. The tumor microenvironment, including the immune cells and related cytokines, is crucial during all the steps of tumor development. In particular, type I and II interferons (IFNs) are involved in a plethora of mechanisms that regulate immune responses in cancer, thus balancing immune escape versus immune surveillance. IFNs are involved in both the direct and indirect regulation of cancer cell proliferation and metastatic potential. The mutational background of genes involved in IFNs signaling could serve as a prognostic biomarker and a powerful tool to screen cancer patients eligible for checkpoint blocking therapies. We herewith describe the latest findings regarding the contribution of IFNs in colorectal cancer and melanoma by researching their dual role as either tumor promoter or suppressor, in diverse tumor types, and microenvironmental context. We are reporting the most innovative and promising approaches of IFN-based therapies that have achieved considerable outcomes in clinical oncology practice and explain the possible mechanisms responsible for their failure.

IL4 Primes the Dynamics of Breast Cancer Progression via DUSP4 Inhibition

The tumor microenvironment supplies proinflammatory cytokines favoring a permissive milieu for cancer cell growth and invasive behavior. Here we show how breast cancer progression is facilitated by IL4 secreted by adipose tissue and estrogen receptor-positive and triple-negative breast cancer cell types. Blocking autocrine and paracrine IL4 signaling with the IL4Rα antagonist IL4DM compromised breast cancer cell proliferation, invasion, and tumor growth by downregulating MAPK pathway activity. IL4DM reduced numbers of CD44⁺/CD24^- cancer stem-like cells and elevated expression of the dual specificity phosphatase DUSP4 by inhibiting NF-κB. Enforced expression of DUSP4 drove conversion of metastatic cells to nonmetastatic cells. Mechanistically, RNAi-mediated attenuation of DUSP4 activated the ERK and p38 MAPK pathways, increased stem-like properties, and spawned metastatic capacity. Targeting IL4 signaling sensitized breast cancer cells to anticancer therapy and strengthened immune responses by enhancing the number of IFNγ-positive CTLs. Our results showed the role of IL4 in promoting breast cancer aggressiveness and how its targeting may improve the efficacy of current therapies. Cancer Res; 77(12); 3268-79. ©2017 AACR.

Targeting DNA double strand break repair with hyperthermia and DNA-PKcs inhibition to enhance the effect of radiation treatment

Radiotherapy is based on the induction of lethal DNA damage, primarily DNA double-strand breaks (DSB). Efficient DSB repair via Non-Homologous End Joining or Homologous Recombination can therefore undermine the efficacy of radiotherapy. By suppressing DNA-DSB repair with hyperthermia (HT) and DNA-PKcs inhibitor NU7441 (DNA-PKcsi), we aim to enhance the effect of radiation.The sensitizing effect of HT for 1 hour at 42°C and DNA-PKcsi [1 μM] to radiation treatment was investigated in cervical and breast cancer cells, primary breast cancer sphere cells (BCSCs) enriched for cancer stem cells, and in an in vivo human tumor model. A significant radio-enhancement effect was observed for all cell types when DNA-PKcsi and HT were applied separately, and when both were combined, HT and DNA-PKcsi enhanced radio-sensitivity to an even greater extent. Strikingly, combined treatment resulted in significantly lower survival rates, 2 to 2.5 fold increase in apoptosis, more residual DNA-DSB 6 h post treatment and a G2-phase arrest. In addition, tumor growth analysis in vivo showed significant reduction in tumor growth and elevated caspase-3 activity when radiation was combined with HT and DNA-PKcsi compared to radiation alone. Importantly, no toxic side effects of HT or DNA-PKcsi were found.In conclusion, inhibiting DNA-DSB repair using HT and DNA-PKcsi before radiotherapy leads to enhanced cytotoxicity in cancer cells. This effect was even noticed in the more radio-resistant BCSCs, which are clearly sensitized by combined treatment. Therefore, the addition of HT and DNA-PKcsi to conventional radiotherapy is promising and might contribute to more efficient tumor control and patient outcome.

Abstract 3311: Autocrine and paracrine IL-4 maintains breast cancer stem cells traits via RAS/MAPK/DUSP pathway

Background:

Despite the advent of successful treatment of localized malignancies, metastatic cancer still lacks efficacious therapeutic approaches, including breast cancer. It is now well established that within malignant tumors Cancer Stem Cells (CSCs) constitute a unique cell subset that fuel and succeed at tumor growth and metastases formation. Tumor microenvironment sustains CSCs characteristics, making the molecular mechanisms driving tumor progression and recurrence more complex and difficult to elucidate. Furthermore, the interaction that occurs between CSCs and the nearby stroma has proven to enhance the aggressive behavior of several carcinomas through the secretion of microenvironmental cytokines. In this context, IL-4 has already been described to promote survival of cancer cells through the up-regulation of several anti-apoptotic factors. However, still little is known about its role in promoting breast cancer progression.

Results:

Here we show for the first time that autocrine and paracrine production of IL-4 regulates breast CSCs (BCSCs) features, including cell proliferation, motility and cytoskeletal organization via RAS/MAPK pathway. Interestingly, relief from IL-4 impaired BCSCs proliferation, colony forming efficiency and in vivo tumor formation, while it fostered the expression of the dual specificity phosphatase-4 (DUSP4) in triple-negative basal-like BCSCs, leading to the decrease of CD44+/CD24- population. DUSP4 is commonly deficient in the most aggressive breast cancers, such as the basal-like subtype. Likewise, we observed that the enforced expression of DUSP4 increases the CD24+ compartment in basal-like BCSCs, determining also a dramatic decrease of their proliferation, colony forming efficiency, invasiveness and metastases formation. Contrarily, in luminal-like BCSCs, DUSP4 suppression favors BCSCs cell traits, including their tumorigenic and metastagenic properties.

Methods:

Patient-derived BCSCs were obtained by digestion of breast cancer tissues and plated in serum-free media with bFGF and EGF. DUSP4 were inserted into the p-Lenti expression vector. Stable DUSP4 knockdown was produced by lentiviral transduction of the pGFP-C vector. IL-4 function was impaired by using a high affinity IL-4Rα antagonist. To assess tumorigenicity and metastases formation, BCSCs were suspended in matrigel and injected either orthotopically or intra caudal in NOD/SCID mice.

Conclusions:

These findings will shed light on the molecular basis of cancer progression and on the complex crosstalk occurring between tumor and its microenvironment. The identification of tumor-related molecular events, such as the IL-4 activated signaling, might be clinically exploited as therapeutic targets in the adjuvant setting and synergize the effect of conventional chemotherapy in patients affected by breast cancers with limited therapeutic options, such as triple-negative breast cancers.

Citation Format: Alice Turdo, Miriam Gaggianesi, Tiziana Apuzzo, Antonina Benfante, Aurora Chinnici, Alessandro Giammona, Simone Di Franco, Giorgio Stassi, Matilde Todaro. Autocrine and paracrine IL-4 maintains breast cancer stem cells traits via RAS/MAPK/DUSP pathway. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3311.

Effect of Restorative Protocol on Cuspal Strain and Residual Stress in Endodontically Treated Molars

Objectives

To evaluate the effect of the restorative protocol on cuspal strain, fracture resistance, residual stress, and mechanical properties of restorative materials in endodontically treated molars.

Methods

Forty-five molars received mesio-occlusal-distal (MOD) Class II preparations and endodontic treatment followed by direct restorations using three restorative protocols: composite resin (CR) only (Filtek Supreme, 3M-ESPE), resin modified glass ionomer cement in combination with CR (Vitremer, 3M-ESPE in pulp chamber and Filtek Supreme in MOD cavity), conventional glass ionomer cement in combination with composite resin (CGI-CR) (Ketac Fil, 3M-ESPE in pulp chamber and Filtek Supreme in MOD cavity). Cuspal strain was measured using strain gauges, and fracture resistance was tested with an occlusal load. Elastic modulus (EM) and Vickers hardness (VH) of the restorative materials were determined at different depths using dynamic microhardness indentation. Curing shrinkage was measured using the strain gauge technique. The restorative protocols were also simulated in finite element analysis (FEA). The shrinkage strain, cuspal strain, EM, VH, and fracture resistance data were statistically analyzed using split-plot analysis of variance and Tukey test (p=0.05). Residual shrinkage stresses were expressed in modified von Mises equivalent stresses.

Results

Shrinkage strain values (in volume %) were Ketac Fil (0.08±0.01) < Vitremer (0.18±0.01) < Filtek Supreme (0.54±0.03). Cuspal strain was higher and fracture resistance was lower when using CR only compared with the techniques that used glass ionomer. The EM and VH of the materials in the pulp chamber were significantly lower for glass ionomer. The FEA showed that using CR only resulted in higher residual stresses in enamel and root dentin close to the pulp chamber than the combinations with glass ionomers (RMGI-CR and CGI-CR).

Conclusions

The choice of restorative protocol significantly affected the biomechanical behavior of endodontically treated molars. Using glass ionomer to fill the pulp chamber is recommended when endodontically treated molars receive direct composite restorations because it reduces cuspal strain and increases fracture resistance.

Lipid droplets: a new player in colorectal cancer stem cells unveiled by spectroscopic imaging

The cancer stem cell (CSC) model is describing tumors as a hierarchical organized system and CSCs are suggested to be responsible for cancer recurrence after therapy. The identification of specific markers of CSCs is therefore of paramount importance. Here, we show that high levels of lipid droplets (LDs) are a distinctive mark of CSCs in colorectal (CR) cancer. This increased lipid content was clearly revealed by label-free Raman spectroscopy and it directly correlates with well-accepted CR-CSC markers as CD133 and Wnt pathway activity. By xenotransplantation experiments, we have finally demonstrated that CR-CSCs overexpressing LDs retain most tumorigenic potential. A relevant conceptual advance in this work is the demonstration that a cellular organelle, the LD, is a signature of CSCs, in addition to molecular markers. A further functional characterization of LDs could lead soon to design new target therapies against CR-CSCs. Stem Cells2015;33:35–44

Effect of Photoactivation Timing on the Mechanical Properties of Resin Cements and Bond Strength of Fiberglass Post to Root Dentin

OBJECTIVES

This study tested the hypothesis that photoactivation timing and resin cement affect mechanical properties and bond strength of fiberglass posts to root dentin at different depths.

METHODS

Fiberglass posts (Exacto, Angelus) were luted with RelyX Unicem (3M ESPE), Panavia F 2.0 (Kuraray), or RelyX ARC (3M ESPE) using three photoactivation timings: light curing immediately, after three minutes, or after five minutes. Push-out bonding strength, PBS (n=10) was measured on each root region (coronal, middle, apical). The elastic modulus (E) and Vickers hardness (VHN) of the cement layer along the root canal were determined using dynamic indentation (n=5). A strain-gauge test was used to measure post-gel shrinkage of each cement (n=10). Residual shrinkage stress was assessed with finite element analysis. Data were analyzed with two-way analysis of variance in a split-plot arrangement and a Tukey test (α=0.05). Multiple linear regression analysis was used to determine the influence of study factors.

RESULTS

The five-minute delay photoactivation timing significantly increased the PBS for all resin cements evaluated. The PBS decreased significantly from coronal to apical root canal regions. The mean values for E and VHN increased significantly with the delayed photoactivation for RelyX Unicem and decreased from coronal to apical root regions for all resin cements with the immediate-curing timing.

CONCLUSIONS

The PBS of fiber posts to root dentin, E, and VHN values were affected by the root canal region, photoactivation timing, and resin cement type. Shrinkage stress values decreased gradually with delayed photoactivation for all the cements.

Abstract LB-143: DNp63 governs metastatic outgrowth of breast cancer stem cells

Background: In the human mammary gland p63 isoforms control mammary epithelial cells fate and DNp63, which lacks the amino-terminal trans-activation domain, counterbalances the full-length isoform TAp63 to allow maturation of epithelia and the maintenance of the myoepithelial/basal cells features. Mammary gland tissue's adult stem cells retain self-renewal and multi-lineage differentiation ability and, by acquiring a malignant behavior, are in charge of tumor seeding. A correlation between Cancer Stem Cells (CSCs) in primary lesions and increased metastatic dissemination has been reported, however, still little is known about the unique profile of distant metastasis’ cell origin. Herein, we show for the first time that breast CSCs (BCSCs) expressing DNp63 are capable to generate metastasis in a preclinical model, while TAp63 can be solely tumorigenic and unable to serial xenografting. We anticipate novel farsighted implications for a prognostic role of p63 and for its targeting to prevent tumor growth and metastatic disease.

Methods: BCSCs were freshly isolated from the histological uninvolved resection of breast cancer tissues. Obtained cells were plated in ultra-low flask in serum-free media in presence of bFGF and EGF. Cells were treated with 1mmol/l doxorubicin hydrochloride. Synthetic genes encoding DNp63 and TAp63 were inserted into the p-TWEEN EGFP lentiviral expression vector. Stable p63 knockdown was produced by lentiviral transduction of the pLentilox 3.7 vector carrying shp63 and scramble sequences. For the tumorigenic and metastagenic assay BCSCs (3×105) were suspended in matrigel and injected orthotopically or in the sub-renal capsule of NOD/SCID mice, respectively. Tumors were measured with a caliper each week and volume was calculated by the formula: π/6 x larger diameter x (smaller diameter)2. Metastasis formation was followed over time and visualized by in vivo imaging.

Summary: Herein, we demonstrate that luminal and basal BCSCs differ in the content of p63 isoforms, DNp63expression was higher in the stem-like compartment of basal BCSCs, compared to TAp63 mainly expressed in bulk primary cells. DNp63 increased the G0-G1 phase in both luminal and basal BCSCs, enhanced doxorubicin resistance and induced a mesenchymal switch. Despite both TAp63 and DNp63 overexpressing BCSCs formed subcutaneous xenografts in NOD/SCID mice, DNp63 cells exclusively retain capabilities of serial xenografting. Thus, suggesting that exogenous expression of TAp63 could promote transition from stem cells to progenitor cells. In a metastatic preclinical model TAp63 overexpression hampered metastatic potential of BCSCs, while DNp63 overexpressing cells gained capabilities to colonize distant organs such as lung and kidney.

Conclusions: These findings state DNp63 as a major regulator of stemness and invasiveness in malignant breast tissues and offer new insights on p63 role as a prognostic biomarker and therapeutic target.

Citation Format: Alice Turdo, Simone Di Franco, Antonina Benfante, Maria Luisa Colorito, Marco Bonanno, Miriam Gaggianesi, Daniela Barcaroli, Francesco Dieli, Jan Paul Medema, Vincenzo De Laurenzi, Giorgio Stassi, Matilde Todaro. DNp63 governs metastatic outgrowth of breast cancer stem cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-143. doi:10.1158/1538-7445.AM2015-LB-143

Incremental filling technique and composite material--part I: cuspal deformation, bond strength, and physical properties

OBJECTIVES

To evaluate the effect of composite resins (one conventional and two low-shrink composites) and filling techniques on cuspal strains (CS), microtensile bond strength (μTBS), composite ultimate tensile strength (UTS), and mechanical properties of the composites at various depths in molars with large Class II restorations.

MATERIALS AND METHODS

One hundred seventeen human molars received standardized Class II mesio-oclusal-distal cavity preparations and restorations with three composites (Filtek LS [3M-ESPE]; Aelite LS [BISCO]; and Filtek Supreme [3M-ESPE]) using three filling techniques (bulk, eight increments, and 16 increments). CS was measured using strain gauges, after which the same restored teeth were used to assess μTBS and UTS. The elastic modulus (E) and Vickers hardness (VH) at different depths were determined from microhardness indentations. The CS, μTBS, UTS, E, and VH data were statistically analyzed using split-plot analysis of variance and Tukey test (p=0.05).

RESULTS

The CS was higher when using 16 increments. The 'low-shrink' composites caused lower CS. The μTBS and UTS were similar for eight- and 16-increment techniques and higher when compared to the bulk filling in all composites. E and VH were constant through the depth when applied in eight or 16 increments.

CONCLUSIONS

Type of composite and filling technique affected the CS, μTBS, UTS, and mechanical properties of large Class II restorations. The eight-increments filling technique resulted in generally less CS with the same μTBS and UTS than was obtained with 16 increments, without affecting E and VH through the depth of the composites.

Tumor and its microenvironment: a synergistic interplay

The mutual and interdependent interaction between tumor and its microenvironment is a crucial topic in cancer research. Recently, it was reported that targeting stromal events could improve efficacies of current therapeutics and prevent metastatic spreading. Tumor microenvironment is a "complex network" of different cell types, soluble factors, signaling molecules and extracellular matrix components, which orchestrate the fate of tumor progression. As by definition, cancer stem cells (CSCs) are proposed to be the unique cell type able to maintain tumor mass and survive outside the primary tumor at metastatic sites. Being exposed to environmental stressors, including reactive oxygen species (ROS), CSCs have developed a GSH-dependent antioxidant system to improve ROS defense capability and acquire a malignant phenotype. Nevertheless, tumor progression is dependent on extracellular matrix remodeling, fibroblasts and macrophages activation in response to oxidative stress, as well as epithelial mesenchymal transition (EMT)-inducing signals and endothelial and perivascular cells recruitment. Besides providing a survival advantage by inducing de novo angiogenesis, tumor-associated vessels contribute to successful dissemination by facilitating tumor cells entry into the circulatory system and driving the formation of pre-metastatic niche. In this review, we focus on the synergistic effect of hypoxia inducible factors (HIFs) and vascular endothelial growth factors (VEGFs) in the successful outgrowth of metastasis, integrating therefore many of the emerging models and theories in the field.

Human NK cells selective targeting of colon cancer-initiating cells: a role for natural cytotoxicity receptors and MHC class I molecules

Tumor cell populations have been recently proposed to be composed of two compartments: tumor-initiating cells characterized by a slow and asymmetrical growth, and the "differentiated" cancer cells with a fast and symmetrical growth. Cancer stem cells or cancer-initiating cells (CICs) play a crucial role in tumor recurrence. The resistance of CICs to drugs and irradiation often allows them to survive traditional therapy. NK cells are potent cytotoxic lymphocytes that can recognize tumor cells. In this study, we have analyzed the NK cell recognition of tumor target cells derived from the two cancer cell compartments of colon adenocarcinoma lesions. Our data demonstrate that freshly purified allogeneic NK cells can recognize and kill colorectal carcinoma-derived CICs whereas the non-CIC counterpart of the tumors (differentiated tumor cells), either autologous or allogeneic, is less susceptible to NK cells. This difference in the NK cell susceptibility correlates with higher expression on CICs of ligands for NKp30 and NKp44 in the natural cytotoxicity receptor (NCR) group of activating NK receptors. In contrast, CICs express lower levels of MHC class I, known to inhibit NK recognition, on their surface than do the "differentiated" tumor cells. These data have been validated by confocal microscopy where NCR ligands and MHC class I molecule membrane distribution have been analyzed. Moreover, NK cell receptor blockade in cytotoxicity assays demonstrates that NCRs play a major role in the recognition of CIC targets. This study strengthens the idea that biology-based therapy harnessing NK cells could be an attractive opportunity in solid tumors.

Proliferation state and polo-like kinase1 dependence of tumorigenic colon cancer cells

Tumor-initiating cells are responsible for tumor maintenance and relapse in solid and hematologic cancers. Although tumor-initiating cells were initially believed to be mainly quiescent, rapidly proliferating tumorigenic cells were found in breast cancer. In colon cancer, the proliferative activity of the tumorigenic population has not been defined, although it represents an essential parameter for the development of more effective therapeutic strategies. Here, we show that tumorigenic colon cancer cells can be found in a rapidly proliferating state in vitro and in vivo, both in human tumors and mouse xenografts. Inhibitors of polo-like kinase1 (Plk1), a mitotic kinase essential for cell proliferation, demonstrated maximal efficiency over other targeted compounds and chemotherapeutic agents in inducing death of colon cancer-initiating cells in vitro. In vivo, Plk1 inhibitors killed CD133(+) colon cancer cells leading to complete growth arrest of colon cancer stem cell-derived xenografts, whereas chemotherapeutic agents only slowed tumor progression. While chemotherapy treatment increased CD133(+) cell proliferation, treatment with Plk1 inhibitors eliminated all proliferating tumor-initiating cells. Quiescent CD133(+) cells that survived the treatment with Plk1 inhibitors could be killed by subsequent Plk1 inhibition when they exited from quiescence. Altogether, these results provide a new insight into the proliferative status of colon tumor-initiating cells both in basal conditions and in response to therapy and indicate Plk1 inhibitors as potentially useful in the treatment of colorectal cancer.

CD133 as a target for colon cancer

INTRODUCTION

Recent evidence based on cancer stem cell (CSC) models, is boosting the progress of translational research and providing relevant clinical implications in many tumour types, including colorectal cancer. The current failure of standard therapies is attributed to a small fraction of the primary cell population with stem-like characteristics, such as self-renewal and differentiation. Identification of CSCs is based on two different criteria of selection: stemness-selective conditions and direct isolation based on putative stem cell markers expression. CD133, a transmembrane glycoprotein, was associated with tumor-initiating cells derived from several histological variants of tumors, including colon.

AREAS COVERED

In this review the current understandings about CD133 as putative marker of tumour-initiating cells in colorectal cancer (CRC) is described. The focus of the discussion is on the need for additional markers to better identify the cell population able to recapitulate the parental tumor in immunocompromised mice.

EXPERT OPINION

Identification and characterization of CSCs represents a relevant issue to define innovative therapeutic approaches, overcoming the emergence of cancer cell clones capable of evading standard therapy.