Endothelial cell-derived interleukin-6 regulates tumor growth

Single-cell transcriptomics reveals activation of endothelial cell and identifies LHPP as a potential target in ulcerative colitis

This study delves into Ulcerative colitis (UC), a persistent gastrointestinal disorder marked by inflammation and ulcers, significantly elevating colorectal cancer risk. The emergence of single-cell RNA sequencing (scRNA-seq) technology has opened new avenues for dissecting the intricate cellular dynamics and molecular mechanisms at play in UC pathology. By analyzing scRNA-seq data from individuals with UC, our study has revealed a consistent enhancement of inflammatory response pathways throughout the course of the disease, alongside detailing the characteristics of endothelial cell damage within colitis environments. A noteworthy finding is the downregulation of Phospholysine Phosphohistidine Inorganic Pyrophosphate Phosphatase (LHPP), which exhibited a inversely correlate with STAT3 expression levels. The markedly reduced expression of LHPP in both the tissues and plasma of UC patients positions LHPP as a compelling target for therapeutic intervention. Our findings highlight the pivotal role LHPP could play in moderating inflammation, spotlighting its potential as a crucial molecular target in the quest to understand and treat UC.

Single-cell analysis identifies phospholysine phosphohistidine inorganic pyrophosphate phosphatase as a target in ulcerative colitis

BACKGROUND

Ulcerative colitis (UC) is a chronic gastrointestinal disorder characterized by inflammation and ulceration, representing a significant predisposition to colorectal cancer. Recent advances in single-cell RNA sequencing (scRNA-seq) technology offer a promising avenue for dissecting the complex cellular inter-actions and molecular signatures driving UC pathology.

AIM

To utilize scRNA-seq technology to dissect the complex cellular interactions and molecular signatures that underlie UC pathology.

METHODS

In this research, we integrated and analyzed the scRNA-seq data from UC patients. Moreover, we conducted mRNA and protein level assays as well as pathology-related staining tests on clinical patient samples.

RESULTS

In this study, we identified the sustained upregulation of inflammatory response pathways during UC progression, characterized the features of damaged endo-thelial cells in colitis. Furthermore, we uncovered the downregulation of phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP) has a negative correlation with signal transducer and activator of transcription 3. Significant downregulation of LHPP in UC patient tissues and plasma suggests that LHPP may serve as a potential therapeutic target for UC. This paper highlights the importance of LHPP as a potential key target in UC and unveils its potential role in inflammation regulation.

CONCLUSION

The findings suggest that LHPP may serve as a potential therapeutic target for UC, emphasizing its importance as a potential key target in UC and unveiling its role in inflammation regulation.

Anti-cancer therapeutic strategies based on HGF/MET, EpCAM, and tumor-stromal cross talk

As an intelligent disease, tumors apply several pathways to evade the immune system. It can use alternative routes to bypass intracellular signaling pathways, such as nuclear factor-κB (NF-κB), Wnt, and mitogen-activated protein (MAP)/phosphoinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR). Therefore, these mechanisms lead to therapeutic resistance in cancer. Also, these pathways play important roles in the proliferation, survival, migration, and invasion of cells. In most cancers, these signaling pathways are overactivated, caused by mutation, overexpression, etc. Since numerous molecules share these signaling pathways, the identification of key molecules is crucial to achieve favorable consequences in cancer therapy. One of the key molecules is the mesenchymal-epithelial transition factor (MET; c-Met) and its ligand hepatocyte growth factor (HGF). Another molecule is the epithelial cell adhesion molecule (EpCAM), which its binding is hemophilic. Although both of them are involved in many physiologic processes (especially in embryonic stages), in some cancers, they are overexpressed on epithelial cells. Since they share intracellular pathways, targeting them simultaneously may inhibit substitute pathways that tumor uses to evade the immune system and resistant to therapeutic agents.

Impact of tumor microenvironment on adoptive T cell transfer activity

Recent advances in immunotherapy have revolutionized the treatment of cancer. The use of adoptive cell therapies (ACT) such as those based on tumor infiltrating lymphocytes (TILs) or genetically modified cells (transgenic TCR lymphocytes or CAR-T cells), has shown impressive results in the treatment of several types of cancers. However, cancer cells can exploit mechanisms to escape from immunosurveillance resulting in many patients not responding to these therapies or respond only transiently. The failure of immunotherapy to achieve long-term tumor control is multifactorial. On the one hand, only a limited percentage of the transferred lymphocytes is capable of circulating through the bloodstream, interacting and crossing the tumor endothelium to infiltrate the tumor. Metabolic competition, excessive glucose consumption, the high level of lactic acid secretion and the extracellular pH acidification, the shortage of essential amino acids, the hypoxic conditions or the accumulation of fatty acids in the tumor microenvironment (TME), greatly hinder the anti-tumor activity of the immune cells in ACT therapy strategies. Therefore, there is a new trend in immunotherapy research that seeks to unravel the fundamental biology that underpins the response to therapy and identifies new approaches to better amplify the efficacy of immunotherapies. In this review we address important aspects that may significantly affect the efficacy of ACT, indicating also the therapeutic alternatives that are currently being implemented to overcome these drawbacks.

Disabling partners in crime: Gold nanoparticles disrupt multicellular communications within the tumor microenvironment to inhibit ovarian tumor aggressiveness

The tumor microenvironment (TME) plays a key role in the poor prognosis of many cancers. However, there is a knowledge gap concerning how multicellular communication among the critical players within the TME contributes to such poor outcomes. Using epithelial ovarian cancer (EOC) as a model, we show how crosstalk among cancer cells (CC), cancer associated fibroblasts (CAF), and endothelial cells (EC) promotes EOC growth. We demonstrate here that co-culturing CC with CAF and EC promotes CC proliferation, migration, and invasion in vitro and that co-implantation of the three cell types facilitates tumor growth in vivo. We further demonstrate that disruption of this multicellular crosstalk using a gold nanoparticle (GNP) inhibits these pro-tumorigenic phenotypes in vitro as well as tumor growth in vivo. Mechanistically, GNP treatment reduces expression of several tumor-promoting cytokines and growth factors, resulting in inhibition of MAPK and PI3K-AKT activation and epithelial-mesenchymal transition - three key oncogenic signaling pathways responsible for the aggressiveness of EOC. The current work highlights the importance of multicellular crosstalk within the TME and its role for the aggressive nature of EOC, and demonstrates the disruption of these multicellular communications by self-therapeutic GNP, thus providing new avenues to interrogate the crosstalk and identify key perpetrators responsible for poor prognosis of this intractable malignancy.

Endothelial Reprogramming Stimulated by Oncostatin M Promotes Inflammation and Tumorigenesis in VHL-Deficient Kidney Tissue

Clear-cell renal cell carcinoma (ccRCC) is the most prevalent subtype of renal cell carcinoma (RCC), and its progression has been linked to chronic inflammation. About 70% of the ccRCC cases are associated with inactivation of the von Hippel-Lindau (VHL) tumor-suppressor gene. However, it is still not clear how mutations in VHL, encoding the substrate-recognition subunit of an E3 ubiquitin ligase that targets the alpha subunit of hypoxia-inducible factor-α (HIFα), can coordinate tissue inflammation and tumorigenesis. We previously generated mice with conditional Vhlh knockout in kidney tubules, which resulted in severe inflammation and fibrosis in addition to hyperplasia and the appearance of transformed clear cells. Interestingly, the endothelial cells (EC), although not subject to genetic manipulation, nonetheless showed profound changes in gene expression that suggest a role in promoting inflammation and tumorigenesis. Oncostatin M (OSM) mediated the interaction between VHL-deficient renal tubule cells and the ECs, and the activated ECs in turn induced macrophage recruitment and polarization. The OSM-dependent microenvironment also promoted metastasis of exogenous tumors. Thus, OSM signaling initiates reconstitution of an inflammatory and tumorigenic microenvironment by VHL-deficient renal tubule cells, which plays a critical role in ccRCC initiation and progression. SIGNIFICANCE: A novel mechanism of cross-talk between ECs and VHL-deficient kidney tubules that stimulates inflammation and tumorigenesis is discovered, suggesting OSM could be a potential target for ccRCC intervention.

Localization of interleukin-6 signaling complex in epithelialized apical lesions of endodontic origin

OBJECTIVES

We aimed to determine the immunolocalization patterns of the interleukin (IL)-6 signaling complex in epithelialized and non-epithelialized apical lesions of endodontic origin (ALEOs).

MATERIALS AND METHODS

Epithelialized (n = 8) and non-epithelialized (n = 7) ALEOs were obtained from teeth with indication of extraction in patients with clinical diagnosis of apical periodontitis. All tissues were subjected to routine processing for histopathologic examination and primary antibodies for IL-6, IL-6 receptor (R), and glycoprotein (gp)-130 were used for immunohistochemistry and double immunofluorescence co-localization.

RESULTS

IL-6, IL-6R, and gp-130 were immunolocalized in endothelial cells and mononuclear leukocytes in a diffuse pattern within the connective tissue of epithelialized and non-epithelialized ALEOs. In the epithelialized lesions, two different patterns were identified: IL-6 signaling complex was localized within the proliferating epithelium in a diffuse intracellular pattern and in a cell membrane localization pattern within the mature epithelial lining, showing a decreased intensity towards the surface layers.

CONCLUSIONS

IL-6, IL-6R, and gp-130 localized to mononuclear inflammatory cells, vascular endothelial cells, and immature proliferating epithelia in a diffuse pattern and in mature lining epithelia in a localized cell membrane pattern, supporting a role for epithelial proliferation during cyst formation. Additional cell membrane co-localization of IL-6 receptor complex suggests classic signaling involvement in addition to trans-signaling.

CAR T cells targeting tumor endothelial marker CLEC14A inhibit tumor growth

Engineering T cells to express chimeric antigen receptors (CARs) specific for antigens on hematological cancers has yielded remarkable clinical responses, but with solid tumors, benefit has been more limited. This may reflect lack of suitable target antigens, immune evasion mechanisms in malignant cells, and/or lack of T cell infiltration into tumors. An alternative approach, to circumvent these problems, is targeting the tumor vasculature rather than the malignant cells directly. CLEC14A is a glycoprotein selectively overexpressed on the vasculature of many solid human cancers and is, therefore, of considerable interest as a target antigen. Here, we generated CARs from 2 CLEC14A-specific antibodies and expressed them in T cells. In vitro studies demonstrated that, when exposed to their target antigen, these engineered T cells proliferate, release IFN-γ, and mediate cytotoxicity. Infusing CAR engineered T cells into healthy mice showed no signs of toxicity, yet these T cells targeted tumor tissue and significantly inhibited tumor growth in 3 mouse models of cancer (Rip-Tag2, mPDAC, and Lewis lung carcinoma). Reduced tumor burden also correlated with significant loss of CLEC14A expression and reduced vascular density within malignant tissues. These data suggest the tumor vasculature can be safely and effectively targeted with CLEC14A-specific CAR T cells, offering a potent and widely applicable therapy for cancer.

T cells expressing a chimeric antigen receptor specific for the tumor vascular marker CLEC14A inhibited tumor growth in three mouse cancer models.

Epigenetic regulation of TLR2-mediated periapical inflammation

AIM

To determine the methylation pattern of TLR2 gene promoter and its association with the transcriptional regulation of periapical inflammatory and angiogenic responses in symptomatic and asymptomatic forms of apical periodontitis.

METHODOLOGY

In this cross-sectional study, apical lesions were obtained from volunteers with asymptomatic apical periodontitis (AAP) (n = 17) and symptomatic apical periodontitis (SAP) (n = 17) scheduled for tooth extraction, and both total RNA and DNA were extracted. DNA was bisulfite-treated, a region of CpG island within the TLR2 gene was amplified by qPCR and the products were sequenced. Additionally, the mRNA expression of TLR2, TLR4, IL-6, IL-12, TNFalpha, IL-23, IL-10, TGFbeta, VEGFA and CDH5 was analysed by qPCR. The data were analysed with chi-square tests, Mann-Whitney or unpaired t-tests, and Spearman´s correlation; variable adjustments were performed using multiple linear regression (P < 0.05).

RESULTS

TLR2 depicted a hypomethylated DNA profile at the CpG island in SAP when compared with AAP, along with upregulated expression of TLR2, with pro-inflammatory cytokines IL-6 and IL-23, and the angiogenesis marker CDH5 (P < 0.05). TLR2 methylation percentage negatively correlated with mRNA levels of IL-23 and CDH5 in apical periodontitis. Lower methylation frequencies of single CpG dinucleotides -8 and -10 localized in close proximity to nuclear factor κB (NFκB) binding within the TLR2 promoter were identified in SAP versus AAP (P < 0.05). Finally, unmethylated -10 and -8 single sites demonstrated up-regulation of IL-23, IL-10 and CDH5 transcripts compared to their methylated counterparts (P < 0.05).

CONCLUSIONS

TLR2 gene promoter hypomethylation was linked to transcriptional activity of pro-inflammatory cytokines and angiogenic markers in exacerbated periapical inflammation. Moreover, unmethylated single sites in close proximity to NFκB binding were involved in active transcription of IL-23, IL-10 and CDH5.

Matrix density drives 3D organotypic lymphatic vessel activation in a microfluidic model of the breast tumor microenvironment

Lymphatic vessels (LVs) have been suggested as a preferential conduit for metastatic progression in breast cancer, where a correlation between the occurrence of lymph node metastasis and an increased extracellular matrix (ECM) density has been reported. However, the effect of ECM density on LV function is largely unknown. To better understand these effects, we used a microfluidic device to recreate tubular LVs in a collagen type I matrix. The density of the matrix was tailored to mimic normal breast tissue using a low-density collagen (LD-3 mg mL-1) and cancerous breast tissue using a high-density collagen (HD-6 mg mL-1). We investigated the effect of ECM density on LV morphology, growth, cytokine secretion, and barrier function. LVs cultured in HD matrices showed morphological changes as compared to LVs cultured in a LD matrix. Specifically, LVs cultured in HD matrices had a 3-fold higher secretion of the pro-inflammatory cytokine, IL-6, and a leakier phenotype, suggesting LVs acquired characteristics of activated vessels. Interestingly, LV leakiness was mitigated by blocking the IL-6 receptor on the lymphatic ECs, maintaining endothelium permeability at similar levels of LV cultured in a LD matrix. To recreate a more in vivo microenvironment, we incorporated metastatic breast cancer cells (MDA-MB-231) into the LD and HD matrices. For HD matrices, co-culture with MDA-MB-231 cells exacerbated vessel leakiness and secretion of IL-6. In summary, our data suggest that (1) ECM density is an important microenvironmental cue that affects LV function in the breast tumor microenvironment (TME), (2) dense matrices condition LVs towards an activated phenotype and (3) blockade of IL-6 signaling may be a potential therapeutic target to mitigate LV dysfunction. Overall, modeling LVs and their interactions with the TME can help identify novel therapeutic targets and, in turn, advance therapeutic discovery.

Interleukin-6 from Adipose-Derived Stem Cells Promotes Tissue Repair by the Increase of Cell Proliferation and Hair Follicles in Ischemia/Reperfusion-Treated Skin Flaps

The most common postoperative complication after reconstructive surgery is flap necrosis. Adipose-derived stem cells (ADSCs) and their secretomes are reported to mediate skin repair. This study was designed to investigate whether conditioned media from ADSCs (ADSC-CM) protects ischemia/reperfusion- (I/R-) induced injury in skin flaps by promoting cell proliferation and increasing the number of hair follicles. The mouse flap model of ischemia was ligating the long thoracic vessels for 3 h, followed by blood reperfusion. ADSC-CM was administered to the flaps, and their survival was observed on postoperative day 5. ADSC-CM treatment led to a significant increase in cell proliferation and the number of hair follicles. IL-6 levels in the lysate and CM from ADSCs were significantly higher than those from Hs68 fibroblasts. Furthermore, a strong decrease in cell proliferation and the number of hair follicles was observed after treatment with IL-6-neutralizing antibodies or si-IL-6-ADSC. In addition, ADSC transplantation increased flap repair, cell proliferation, and hair follicle number in I/R injury of IL-6-knockout mice. In conclusion, IL-6 secreted from ADSCs promotes the survival of I/R-induced flaps by increasing cell proliferation and the number of hair follicles. ADSCs represent a promising therapy for preventing skin flap necrosis following reconstructive and plastic surgery.

IL-6 Mediates Cross-Talk between Tumor Cells and Activated Fibroblasts in the Tumor Microenvironment

The tumor microenvironment (TME) plays a major role in the pathogenesis of multiple cancer types, including upper-gastrointestinal (GI) cancers that currently lack effective therapeutic options. Cancer-associated fibroblasts (CAF) are an essential component of the TME, contributing to tumorigenesis by secreting growth factors, modifying the extracellular matrix, supporting angiogenesis, and suppressing antitumor immune responses. Through an unbiased approach, we have established that IL-6 mediates cross-talk between tumor cells and CAF not only by supporting tumor cell growth, but also by promoting fibroblast activation. As a result, IL-6 receptor (IL6Rα) and downstream effectors offer opportunities for targeted therapy in upper-GI cancers. IL-6 loss suppressed tumorigenesis in physiologically relevant three-dimensional (3D) organotypic and 3D tumoroid models and murine models of esophageal cancer. Tocilizumab, an anti-IL6Rα antibody, suppressed tumor growth in vivo in part via inhibition of STAT3 and MEK/ERK signaling. Analysis of a pan-cancer TCGA dataset revealed an inverse correlation between IL-6 and IL6Rα overexpression and patient survival. Therefore, we expanded evaluation of tocilizumab to head and neck squamous cell carcinoma patient-derived xenografts and gastric adenocarcinoma xenografts, demonstrating suppression of tumor growth and altered STAT3 and ERK1/2 gene signatures. We used small-molecule inhibitors of STAT3 and MEK1/2 signaling to suppress tumorigenesis in the 3D organotypic model of esophageal cancer. We demonstrate that IL6 is a major contributor to the dynamic cross-talk between tumor cells and CAF in the TME. Our findings provide a translational rationale for inhibition of IL6Rα and downstream signaling pathways as a novel targeted therapy in oral-upper-GI cancers.Significance: These findings demonstrate the interaction of esophageal cancer and cancer-associated fibroblasts through IL-6 signaling, providing rationale for a novel therapeutic approach to target these cancers. Cancer Res; 78(17); 4957-70. ©2018 AACR.

A mathematical model for IL-6-mediated, stem cell driven tumor growth and targeted treatment

Targeting key regulators of the cancer stem cell phenotype to overcome their critical influence on tumor growth is a promising new strategy for cancer treatment. Here we present a modeling framework that operates at both the cellular and molecular levels, for investigating IL-6 mediated, cancer stem cell driven tumor growth and targeted treatment with anti-IL6 antibodies. Our immediate goal is to quantify the influence of IL-6 on cancer stem cell self-renewal and survival, and to characterize the subsequent impact on tumor growth dynamics. By including the molecular details of IL-6 binding, we are able to quantify the temporal changes in fractional occupancies of bound receptors and their influence on tumor volume. There is a strong correlation between the model output and experimental data for primary tumor xenografts. We also used the model to predict tumor response to administration of the humanized IL-6R monoclonal antibody, tocilizumab (TCZ), and we found that as little as 1mg/kg of TCZ administered weekly for 7 weeks is sufficient to result in tumor reduction and a sustained deceleration of tumor growth.

A small population of cancer stem cells that share many of the biological characteristics of normal adult stem cells are believed to initiate and sustain tumor growth for a wide variety of malignancies. Growth and survival of these cancer stem cells is highly influenced by tumor micro-environmental factors and molecular signaling initiated by cytokines and growth factors. This work focuses on quantifying the influence of IL-6, a pleiotropic cytokine secreted by a variety of cell types, on cancer stem cell self-renewal and survival. We present a mathematical model for IL-6 mediated, cancer stem cell driven tumor growth that operates at the following levels: (1) the molecular level—capturing cell surface dynamics of receptor-ligand binding and receptor activation that lead to intra-cellular signal transduction cascades; and (2) the cellular level—describing tumor growth, cellular composition, and response to treatments targeted against IL-6.

The roles of signal transducer and activator of transcription factor 3 in tumor angiogenesis

Angiogenesis is the development of new blood vessels, which is required for tumor growth and metastasis. Signal transducer and activator of transcription factor 3 (STAT3) is a transcription factor that regulates a variety of cellular events including proliferation, differentiation and apoptosis. Previous studies revealed that activation of STAT3 promotes tumor angiogenesis. In this review, we described the activities of STAT3 signaling in different cell types involved in angiogenesis. Particularly, we elucidated the molecular mechanisms of STAT3-mediated gene regulation in angiogenic endothelial cells in response to external stimulations such as hypoxia and inflammation. The potential for STAT3 as a therapeutic target was also discussed. Overall, this review provides mechanistic insights for the roles of STAT3 signaling in tumor angiogenesis.

Adipose-Derived Stem Cells Protect Skin Flaps against Ischemia/Reperfusion Injury via IL-6 Expression

Flap necrosis is the most frequent postoperative complication encountered in reconstructive surgery. We elucidated whether adipose-derived stem cells (ADSCs) and their derivatives might induce neovascularization and protect skin flaps during ischemia/reperfusion (I/R) injury. Flaps were subjected to 3 hours of ischemia by ligating long thoracic vessels and then to blood reperfusion. Qtracker-labeled ADSCs, ADSCs in conditioned medium (ADSC-CM), or ADSC exosomes (ADSC-Exo) were injected into the flaps. These treatments led to significantly increased flap survival and capillary density compared with I/R on postoperative day 5. IL-6 levels in the cell lysates or in conditioned medium were significantly higher in ADSCs than in Hs68 fibroblasts. ADSC-CM and ADSC-Exo increased tube formation. This result was corroborated by a strong decrease in skin repair after adding IL-6-neutralizing antibodies or small interfering RNA for IL-6 ADSCs. ADSC transplantation also increased flap recovery in I/R injury of IL-6-knockout mice. IL-6 was secreted from ADSCs through signal transducer and activator of transcription phosphorylation, and then IL-6 stimulated angiogenesis and enhanced recovery after I/R injury by the classic signaling pathway. The mechanism of skin recovery includes the direct differentiation of ADSCs into endothelial cells and the indirect effect of IL-6 released from ADSCs. ADSC-CM and ADSC-Exo could be used as off-the-shelf products for this therapy.

Cancer development, chemoresistance, epithelial to mesenchymal transition and stem cells: A snapshot of IL-6 mediated involvement

Interleukin-6 (IL-6) is a cytokine present in tumor microenvironment. Elevated level of IL-6 is associated with cancer cell proliferation, angiogenesis and metastasis through fueling STAT3, MAPK and Akt signaling. It promotes epithelial to mesenchymal transition (EMT) through altered expression of N-cadherin, vimentin, snail, twist and E-cadherin leading to cancer metastasis. IL-6 boosts mammosphere formation, self-renewal of stem cells, stemness properties of cancer cells and recruitment of mesenchymal stem cells. IL-6 is also a contributing factor for multidrug resistance in cancer due to gp130/MAPK/STAT3 mediated activation of transcription factors C/EBPβ/δ, overexpression of p-glycoprotein, EMT transition and expansion of stem cells. The in-depth investigation of IL-6 mediated cellular effects and its signaling pathway can provide the new window for future research and clinical development of IL-6 targeted therapy in cancer. Thus, an overview is delivered in this review deciphering the emerging aspect of the predominant influence of IL-6 in malignant transformation, EMT, cancer-associated stem cells and chemoresistance.

Anti-tumor effect of inhibition of IL-6 signaling in mucoepidermoid carcinoma

Mucoepidermoid carcinoma (MEC) is the most frequent malignant salivary gland cancer. Response to chemoradiotherapy is modest, and therefore radical surgery remains the standard-of-care. Emerging evidence suggests that Interleukin (IL)-6 signaling correlates with the survival of cancer stem cells and resistance to therapy. Here, we investigated whether inhibition of IL-6 receptor (IL-6R) signaling with tocilizumab (humanized anti-human IL-6R antibody) sensitizes MEC to chemotherapy using human mucoepidermoid carcinoma cell lines (UM-HMC) and correspondent xenograft models. In vitro, we observed that tocilizumab inhibited STAT3 phosphorylation but had no measurable effect in MEC cell viability (UM-HMC-1,-3A,-3B). In contrast, the anti-tumor effect of single agent tocilizumab on MEC xenografts was comparable to paclitaxel or cisplatin. Combination of tocilizumab with cisplatin or paclitaxel enhanced the inhibitory effect of chemotherapy on xenograft growth (P < 0.05), time to failure (P < 0.01), decreased vascular endothelial growth factor (VEGF) expression and tumor microvessel density (P < 0.05) without added systemic toxicities. Notably, tocilizumab decreased the fraction of MEC cancer stem cells (ALDH(high)CD44(high)) in vitro, and prevented paclitaxel-induced increase in the fraction of cancer stem cells in vivo (P < 0.05). Collectively, these findings demonstrate that tocilizumab enhances the anti-tumor effect of conventional chemotherapy in preclinical models of mucoepidermoid carcinoma, and suggest that patients might benefit from combination therapy with an inhibitor of IL-6R signaling and chemotherapeutic agent such as paclitaxel.

Endothelial interleukin-6 defines the tumorigenic potential of primary human cancer stem cells

Head and neck squamous cell carcinomas (HNSCC) contain a small subpopulation of stem cells endowed with unique capacity to generate tumors. These cancer stem cells (CSC) are localized in perivascular niches and rely on crosstalk with endothelial cells for survival and self-renewal, but the mechanisms involved are unknown. Here, we report that stromal interleukin (IL)-6 defines the tumorigenic capacity of CSC sorted from primary human HNSCC and transplanted into mice. In search for the cellular source of Interleukin-6 (IL-6), we observed a direct correlation between IL-6 levels in tumor-associated endothelial cells and the tumorigenicity of CSC. In vitro, endothelial cell-IL-6 enhanced orosphere formation, p-STAT3 activation, survival, and self-renewal of human CSC. Notably, a humanized anti-IL-6R antibody (tocilizumab) inhibited primary human CSC-mediated tumor initiation. Collectively, these data demonstrate that endothelial cell-secreted IL-6 defines the tumorigenic potential of CSC, and suggest that HNSCC patients might benefit from therapeutic inhibition of IL-6/IL-6R signaling.

In vitro microtumors provide a physiologically predictive tool for breast cancer therapeutic screening

Many anti-cancer drugs fail in human trials despite showing efficacy in preclinical models. It is clear that the in vitro assays involving 2D monoculture do not reflect the complex extracellular matrix, chemical, and cellular microenvironment of the tumor tissue, and this may explain the failure of 2D models to predict clinical efficacy. We first optimized an in vitro microtumor model using a tumor-aligned ECM, a tumor-aligned medium, MCF-7 and MDA-MB-231 breast cancer spheroids, human umbilical vein endothelial cells, and human stromal cells to recapitulate the tissue architecture, chemical environment, and cellular organization of a growing and invading tumor. We assayed the microtumor for cell proliferation and invasion in a tumor-aligned extracellular matrix, exhibiting collagen deposition, acidity, glucose deprivation, and hypoxia. We found maximal proliferation and invasion when the multicellular spheroids were cultured in a tumor-aligned medium, having low pH and low glucose, with 10% fetal bovine serum under hypoxic conditions. In a 7-day assay, varying doses of fluorouracil or paclitaxel had differential effects on proliferation for MCF-7 and MDA-MB-231 tumor spheroids in microtumor compared to 2D and 3D monoculture. The microtumors exhibited a tumor morphology and drug response similar to published xenograft data, thus demonstrating a more physiologically predictive in vitro model.

Paired single cell co-culture microenvironments isolated by two-phase flow with continuous nutrient renewal

Cancer-stromal cell interactions are a critical process in tumorigenesis. Conventional dish-based assays, which simply mix two cell types, have limitations in three aspects: 1) limited control of the cell microenvironment; 2) inability to study cell behavior in a single-cell manner; and 3) have difficulties in characterizing single cell behavior within a highly heterogeneous cell population (e.g. tumor). An innovative use of microfluidic technology is for improving the spatial resolution for single cell assays. However, it is challenging to isolate the paired interacting cells while maintaining nutrient renewal. In this work, two-phase flow was used as a simple isolation method, separating the microenvironment of each individual chamber. As nutrients in an isolated chamber are consumed by cells, media exchange is required. To connect the cell culture chamber to the media exchange layer, we demonstrated a 3D microsystem integration technique using vertical connections fabricated by deep reactive-ion etching (DRIE). Compared to previous approaches, the presented process allows area reduction of vertical connections by an order of magnitude, enabling compact 3D integration. A semi-permeable membrane was sandwiched between the cell culture layer and the media exchange layer. The selectivity of the semi-permeable membrane results in the retention of the signaling proteins within the chamber while allowing free diffusion of nutrients (e.g., glucose and amino acids). Thus, paracrine signals are accumulated inside the chamber without cross-talk between cells in other chambers. Utilizing these innovations, we co-cultured UM-SCC-1 (head and neck squamous cell carcinoma) cells and endothelial cells to simulate tumor proliferation enhancement in the vascular endothelial niche.

Lymphatic endothelial cells support tumor growth in breast cancer

Tumor lymphatic vessels (LV) serve as a conduit of tumor cell dissemination, due to their leaky nature and secretion of tumor-recruiting factors. Though lymphatic endothelial cells (LEC) lining the LV express distinct factors (also called lymphangiocrine factors), these factors and their roles in the tumor microenvironment are not well understood. Here we employ LEC, microvascular endothelial cells (MEC), and human umbilical vein endothelial cells (HUVEC) cultured in triple-negative MDA-MB-231 tumor-conditioned media (TCM) to determine the factors that may be secreted by various EC in the MDA-MB-231 breast tumor. These factors will serve as endothelium derived signaling molecules in the tumor microenvironment. We co-injected these EC with MDA-MB-231 breast cancer cells into animals and showed that LEC support tumor growth, HUVEC have no significant effect on tumor growth, whereas MEC suppress it. Focusing on LEC-mediated tumor growth, we discovered that TCM-treated LEC (‘tumor-educated LEC') secrete high amounts of EGF and PDGF-BB, compared to normal LEC. LEC-secreted EGF promotes tumor cell proliferation. LEC-secreted PDGF-BB induces pericyte infiltration and angiogenesis. These lymphangiocrine factors may support tumor growth in the tumor microenvironment. This study shows that LV serve a novel role in the tumor microenvironment apart from their classical role as conduits of metastasis.