Cancer biology. All in the stroma: cancer's Cosa Nostra

Circulating Tumor Microenvironment in Metastasis

Activation of invasion and metastasis is a central hallmark of cancer, contributing to the primary cause of death for patients with cancer. In the multistep metastatic process, cancer cells must infiltrate the circulation, survive, arrest at capillary beds, extravasate, and form metastatic clones in distant organs. However, only a small proportion of circulating tumor cells (CTC) successfully form metastases, with transit of CTCs in the circulation being the rate-limiting step. The fate of CTCs is influenced by the circulating tumor microenvironment (cTME), which encompasses factors affecting their biological behaviors in the circulation. This liquid and flowing microenvironment differs significantly from the primary TME or the premetastatic niche. This review summarizes the latest advancements in identifying the biophysical cues, key components, and biological roles of the cTME, highlighting the network among biophysical attributes, blood cells, and nonblood factors in cancer metastasis. In addition to the potential of the cTME as a therapeutic target for inhibiting metastasis, the cTME could also represent as a biomarker for predicting patient outcomes and developing strategies for treating cancer.

CAFs secrete CXCL12 to accelerate the progression and cisplatin resistance of colorectal cancer through promoting M2 polarization of macrophages

The purpose of this study was to investigate the effect of the interaction between tumor-associated fibroblasts (CAFs) and macrophage polarization on colorectal cancer (CRC) progression. Clinical tissue samples of CRC and health volunteers were collected to isolate normal fibroblasts (NFs) and CAFs. LoVo, HCT116, or THP-1 cells were co-cultured with NFs or CAFs. Immunofluorescence and western blot detected the expression of related markers. MTT assay measured cell viability and IC50. Cell proliferation and metastasis were detected through colony formation and transwell assays. CRC mice models were constructed by injection of HCT116 cells, with IHC assessing C-X-C Motif Chemokine Ligand 12 (CXCL12) expression. The proliferation, migration, invasion, and cisplatin (DDP) resistance of CRC cells were apparently increased after co-culture with CAFs. Compared to NFs, CAFs have a markedly higher ability to recruit macrophages and promote macrophages M2 polarization by secreting CXCL12. Further experiments affirmed that CXCL12 secreted by CAFs boosted proliferation, migration, invasion, and DDP resistance of CRC cells via induction of the M2 polarization of macrophages. In vivo experiments confirmed that CAFs promoted the progression of CRC and DDP resistance by affecting M2 polarization through CXCL12. CAFs recruit macrophages and secrete CXCL12 to induce M2 polarization of macrophages, thus mediating cell function and DDP resistance of CRC.

A Bloody Conspiracy. Blood Vessels and Immune Cells in the Tumor Microenvironment

Simple Summary

The tumor microenvironment has risen over the last years as a significant contributor to the failure of antitumoral strategies due to its numerous pro-tumorigenic activities. In this review, we focused on two features of this microenvironment, namely angiogenesis and immunity, which have been the targets of therapies to tackle tumors via its microenvironmental part over the last decade. Increasing our knowledge of the complex interactions within this ecosystem is mandatory to optimize these therapeutic approaches. The development of innovative experimental models is of great help in reaching this goal.

Abstract

Cancer progression occurs in concomitance with a profound remodeling of the cellular microenvironment. Far from being a mere passive event, the re-orchestration of interactions between the various cell types surrounding tumors highly contributes to the progression of the latter. Tumors notably recruit and stimulate the sprouting of new blood vessels through a process called neo-angiogenesis. Beyond helping the tumor cope with an increased metabolic demand associated with rapid growth, this also controls the metastatic dissemination of cancer cells and the infiltration of immune cells in the tumor microenvironment. To decipher this critical interplay for the clinical progression of tumors, the research community has developed several valuable models in the last decades. This review offers an overview of the various instrumental solutions currently available, including microfluidic chips, co-culture models, and the recent rise of organoids. We highlight the advantages of each technique and the specific questions they can address to better understand the tumor immuno-angiogenic ecosystem. Finally, we discuss this development field’s fundamental and applied perspectives.

Reconceptualize tall-cell variant papillary thyroid microcarcinoma: From a "sonographic histology" perspective

OBJECTIVE

This study aimed to examine the relationship between sonographic features and histological manifestations in the tall-cell variant of papillary thyroid microcarcinoma (TCV-PTMC), thus proposing the concept of "sonographic histology" and examine its value in the clinical management of the aggressive tall-cell variant.

METHODS

This study retrospectively included 104 participants who were admitted to Peking University Third Hospital from 2015 to 2022 and were histopathologically confirmed as having TCV-PTMC or classical PTMC. We mainly compared the general characteristics, sonographic characteristics, and pathological specimens between the two cohorts.

RESULTS

Hypoechoic nodules with a localized central isoechoic lesion and hypoechoic halo around nodules were most often observed in TCV-PTMC, which correlated with circumferentially distributed tumor epithelium and densely distributed tumor stroma histopathologically. Additionally, TCV-PTMC showed nodules with a more regular margin and less microcalcification than classical PTMC, which led to an underestimation of the risk of TCV-PTMC.

CONCLUSION

The good association between the ultrasound echo pattern and tissue cell arrangement was defined as sonographic histology in this study and can be applied in the preoperative identification of TCV-PTMC. This concept may provide novel insight for the identification of special subtypes of thyroid tumors and may modify pitfalls of the Thyroid Imaging Reporting and Data System in aggressive variants of microcarcinoma.

Catecholamine levels and gene expression of their receptors in tissues of adults with osteosarcoma

AIM

The purpose of this work was to identify and measure catecholamines, their metabolites, and the gene expression of catecholamine receptors in osteosarcoma tissue.

MATERIALS AND METHODS

The levels of 3,4-dihydroxyphenylacetic acid, norepinephrine, serotonin, and 5-hydroxyindoleacetic acid in cancer tissue and in adjacent and non-oncological bone tissue were analysed by high-performance liquid chromatography, and the gene expression of catecholamine receptors and of dopamine β-hydroxylase, monoaminoxidase, ki67, and Runx2 in the osteosarcoma tissue, tissue adjacent to the tumour, non-oncological bone, and human brain tissue was analysed by RT-PCR.

RESULTS

We found significantly higher levels of 3,4-dihydroxyphenylacetic acid and norepinephrine in the cancer sample than in adjacent and non-oncological bone. We found that β-adrenergic receptors and dopaminergic receptors, dopamine β-hydroxylase, ki67, Runx2, and serotonergic receptor gene expression were significantly higher in tumour tissue than in adjacent and non-oncological bone.

CONCLUSION

Catecholamines and their receptors could be potential molecular markers for osteosarcoma progression.

The Role of Tubule-Interstitial Crosstalk in Renal Injury and Recovery

Renal epithelial cells show remarkable regenerative capacity to recover from acute injury, which involves specific phenotypic changes, but also significant profibrotic tubule-interstitial crosstalk. Tubule-derived profibrotic stimuli and subsequent myofibroblast activation and extracellular matrix deposition have been linked closely with decline of renal function and nephron loss. However, recent data have questioned the view of purely detrimental effects of myofibroblast activation in the injured kidney and even suggested its beneficial role for epithelial regeneration. This article reviews the current understanding of the underlying mechanisms of tubular cell turnover, new suggested pathways of proregenerative tubular-interstitial crosstalk, and relevant insights of proliferation-enhancing effects of myofibroblasts on epithelial cells in nonrenal tissues.

Assessment of protein biomarkers for preoperative differential diagnosis between benign and malignant ovarian tumors

OBJECTIVE

To estimate the diagnostic value of tumor and immune related proteins in the discrimination between benign and malignant adnexal masses, and between different subgroups of tumors.

METHODS

In this exploratory diagnostic study, 254 patients with an adnexal mass scheduled for surgery were consecutively enrolled at the University Hospitals Leuven (128 benign, 42 borderline, 22 stage I, 55 stage II-IV, and 7 secondary metastatic tumors). The quantification of 33 serum proteins was done preoperatively, using multiplex high throughput immunoassays (Luminex) and electrochemiluminescence immuno-assay (ECLIA). We calculated univariable areas under the Receiver Operating Characteristic Curves (AUCs). To discriminate malignant from benign tumors, multivariable ridge logistic regression with backward elimination was performed, using bootstrapping to validate the resulting AUCs.

RESULTS

CA125 had the highest univariable AUC to discriminate malignant from benign tumors (0.85, 95% confidence interval 0.79-0.89). Combining CA125 with CA72.4 and HE4 increased the AUC to 0.87. For benign vs borderline tumors, CA125 had the highest univariable AUC (0.74). For borderline vs stage I malignancy, no proteins were promising. For stage I vs II-IV malignancy, CA125, HE4, CA72.4, CA15.3 and LAP had univariable AUCs ≥0.80.

CONCLUSIONS

The results confirm the dominant role of CA125 for identifying malignancy, and suggest that other markers (HE4, CA72.4, CA15.3 and LAP) may help to distinguish between stage I and stage II-IV malignancies. However, further research is needed, also to investigate the added value over clinical and ultrasound predictors of malignancy, focusing on the differentiation between subtypes of malignancy.

Single Cell Mass Cytometry Revealed the Immunomodulatory Effect of Cisplatin Via Downregulation of Splenic CD44+, IL-17A+ MDSCs and Promotion of Circulating IFN-γ+ Myeloid Cells in the 4T1 Metastatic Breast Cancer Model

The treatment of metastatic breast cancer remained a challenge despite the recent breakthrough in the immunotherapy regimens. Here, we addressed the multidimensional immunophenotyping of 4T1 metastatic breast cancer by the state-of-the-art single cell mass cytometry (CyTOF). We determined the dose and time dependent cytotoxicity of cisplatin on 4T1 cells by the xCelligence real-time electronic sensing assay. Cisplatin treatment reduced tumor growth, number of lung metastasis, and the splenomegaly of 4T1 tumor bearing mice. We showed that cisplatin inhibited the tumor stroma formation, the polarization of carcinoma-associated fibroblasts by the diminished proteolytic activity of fibroblast activating protein. The CyTOF analysis revealed the emergence of CD11b+/Gr-1+/CD44+ or CD11b+/Gr-1+/IL-17A+ myeloid-derived suppressor cells (MDSCs) and the absence of B220+ or CD62L+ B-cells, the CD62L+/CD4+ and CD62L+/CD8+ T-cells in the spleen of advanced cancer. We could show the immunomodulatory effect of cisplatin via the suppression of splenic MDSCs and via the promotion of peripheral IFN-γ+ myeloid cells. Our data could support the use of low dose chemotherapy with cisplatin as an immunomodulatory agent for metastatic triple negative breast cancer.

TIPE1 suppresses osteosarcoma tumor growth by regulating macrophage infiltration

BACKGROUND

Osteosarcoma is the most common primary malignancy of the bone, and macrophages play a promotional role during osteosarcoma development and progression. TIPE1 is known to function as a tumor suppressor in diverse cancers by inducing cell arrest and apoptosis. However, the biological function of TIPE1 in osteosarcoma is still unclear.

PURPOSE

The purpose of this study was to investigate the expression and function of TIPE1 in osteosarcoma.

METHODS

In the present study, TIPE1 expression in osteosarcoma cancer cells was determined by qPCR and western blotting. A subcutaneous tumor model was established to investigate the potential anti-tumor activity of TIPE1 in osteosarcoma. Further, flow cytometry, western blotting, immunofluorescence staining, and ELISA were performed to clarify the underlying mechanism by which TIPE1 regulates growth of osteosarcoma.

RESULTS

Our results suggest that TIPE1 is downregulated in osteosarcoma cancer cells, and ectopic expression TIPE1 significantly inhibited osteosarcoma tumor growth in vivo. Furthermore, TIPE1 inhibits the infiltration of macrophages in osteosarcoma tumor by suppressing MCP-1 expression in osteosarcoma cells. Further in vivo study revealed that inhibition of MCP-1/CCR2 axis by Bindarit blocked the inhibitory effect of TIPE1 on osteosarcoma growth.

CONCLUSION

Collectively, our results demonstrate the anti-tumor role of TIPE1 in osteosarcoma and reveal a novel therapy target for osteosarcoma.

Mesenchymal stem cells up-regulate the invasive potential of prostate cancer cells via the eotaxin-3/CCR3 axis

This study aimed to clarify the role of mesenchymal stem cells (MSCs) as a component of the cancer microenvironment. We investigated the homing-related chemokine expression levels of MSCs treated with a prostate cancer cell line (PC-3) -conditioned medium. Among several homing chemokines, an antibody array revealed that expression of eotaxin-3 (but not eotxin-1 and -2) was highly enhanced in MSCs treated with PC-3-conditioned medium. A gene expression array showed significantly increased expression of CCR3, a receptor of eotaxin-3, in PC-3. In a matrigel invasion assay, interferon-gamma, a specific inhibitor of eotaxin-related homing, significantly reduced the transmigration of PC-3 cells, under co-cultured condition with MSCs, in a dose-dependent manner (P < 0.05). Consistent with these results, anti-CCR3 antibody successfully reduced PC-3 migration under the co-cultured condition. These findings suggest that MSCs to modulation of the invasive potential of prostate cancer cells via the eotaxin-3/CCR3 axis.

miRNA-1246 induces pro-inflammatory responses in mesenchymal stem/stromal cells by regulating PKA and PP2A

The tumor microenvironment (TME) has an impact on breast cancer progression by creating a pro-inflammatory milieu within the tumor. However, little is known about the roles of miRNAs in cells of the TME during this process. We identified six putative oncomiRs in a breast cancer dataset, all strongly correlating with poor overall patient survival. Out of the six candidates, miR-1246 was upregulated in aggressive breast cancer subtypes and expressed at highest levels in mesenchymal stem/stroma cells (MSCs). Functionally, miR-1246 led to a p65-dependent increase in transcription and release of pro-inflammatory mediators IL-6, CCL2 and CCL5 in MSCs, and increased NF-κB activity. The pro-inflammatory phenotype of miR-1246 in MSCs was independent of TNFα stimulations and mediated by direct targeting of the tumor-suppressors PRKAR1A and PPP2CB. In vitro recapitulation of the TME revealed increased Stat3 phosphorylation in breast epithelial (MCF10A) and cancer cells (SK-BR-3, MCF7, T47D) upon incubation with conditioned medium (CM) of MSCs overexpressing miR-1246. Additionally, this stimulation enhanced proliferation of MCF10A cells, increased migration of MDA-MB-231 cells and induced attraction of THP-1 monocytic cells. Our data shows that miR-1246 acts as both key-enhancer of pro-inflammatory responses in MSCs and putative oncomiR in breast cancer, suggesting its influence on cancer-related inflammation and breast cancer progression.

Galectins: Multitask signaling molecules linking fibroblast, endothelial and immune cell programs in the tumor microenvironment

Tumor cells corrupt surrounding normal cells instructing them to support proliferative, pro-angiogenic and immunosuppressive networks that favor tumorigenesis and metastasis. This dynamic cross-talk is sustained by a range of intracellular signals and extracellular mediators produced by both tumoral and non-tumoral cells. Galectins -whether secreted or intracellularly expressed- play central roles in the tumorigenic process by delivering regulatory signals that contribute to reprogram fibroblasts, endothelial and immune cell programs. Through glycosylation-dependent or independent mechanisms, these endogenous lectins control a variety of cellular events leading to tumor cell proliferation, survival, migration, inflammation, angiogenesis and immune escape. Here we discuss the role of galectin-driven pathways, particularly those activated in non-tumoral stromal cells, in modulating tumor progression.

Prominent role of RAB39A-RXRB axis in cancer development and stemness

In this study, we found that RAB39A, a member of the RAS oncogene family, was selectively expressed in cancer cells of different histotypes, by analyzing gene expression in human osteosarcoma cells and the cancer stem cells (CSCs) and by comparing them with normal cells through global transcriptomics and principal component analyses. We further validated RAB39A as a therapeutic target, by silencing its expression. The silencing impaired cancer stemness and spherogenic ability in vitro, as well as tumorigenesis in vivo. RNA-seq analyses in the silenced spheres suggested that RAB39A is associated downstream with RXRB and KLF4. Notably, RXRB expression was inhibited in RAB39A-silenced CSCs. Induced overexpression of RXRB in RAB39A-silenced cells restored spherogenic ability and tumorigenesis, confirming RXRB as a major effector of RAB39A. Quantitative RT-PCR analysis of ∼400 human cancer tissues showed that RAB39A was highly expressed in sarcomas and in malignancies of lymphoid, adrenal and testicular tissues. Our data provide the rationale for targeting of the RAB39A-RXRB axis as a therapy for aggressive cancers.

Thinking in three dimensions: discovering reciprocal signaling between the extracellular matrix and nucleus and the wisdom of microenvironment and tissue architecture

I thought long and hard whether I could avoid talking about family and personal life, and just share the excitement of being a scientist and how science continues to sustain us all. But so many people, especially younger scientists, want to know-and always ask-How did you do it? A woman from Iran, a Middle Eastern country and essentially Muslim, now considered backwards and misguided if not downright scary, traveling very young and alone to the United States, finishing college and graduate school together with having children, first-year graduate school and second-year post doc-years ago, going against a number of entrenched dogmas, and yet succeeding against many odds and obstacles, and all the while on soft money? Below is my personal narrative answering some of these questions.

Cancer-associated mesenchymal stroma fosters the stemness of osteosarcoma cells in response to intratumoral acidosis via NF-κB activation

The role of mesenchymal stem cells (MSC) in osteosarcoma (OS), the most common primary tumor of bone, has not been extensively elucidated. We have recently shown that OS is characterized by interstitial acidosis, a microenvironmental condition that is similar to a wound setting, in which mesenchymal reactive cells are activated to release mitogenic and chemotactic factors. We therefore intended to test the hypothesis that, in OS, acid-activated MSC influence tumor cell behavior. Conditioned media or co-culture with normal MSC previously incubated with short-term acidosis (pH 6.8 for 10 hr, H⁺ -MSC) enhanced OS clonogenicity and invasion. This effect was mediated by NF-κB pathway activation. In fact, deep-sequencing analysis, confirmed by Real-Time PCR and ELISA, demonstrated that H⁺ -MSC differentially induced a tissue remodeling phenotype with increased expression of RelA, RelB and NF-κB1, and downstream, of CSF2/GM-CSF, CSF3/G-CSF and BMP2 colony-promoting factors, and of chemokines (CCL5, CXCL5 and CXCL1), and cytokines (IL6 and IL8), with an increased expression of CXCR4. An increased expression of IL6 and IL8 were found only in normal stromal cells, but not in OS cells, and this was confirmed in tumor-associated stromal cells isolated from OS tissue. Finally, H⁺ -MSC conditioned medium differentially promoted OS stemness (sarcosphere number, stem-associated gene expression), and chemoresistance also via IL6 secretion. Our data support the hypothesis that the acidic OS microenvironment is a key factor for MSC activation, in turn promoting the secretion of paracrine factors that influence tumor behavior, a mechanism that holds the potential for future therapeutic interventions aimed to target OS.

C/EBP-δ positively regulates MDSC expansion and endothelial VEGFR2 expression in tumor development

Vascular endothelial cells and Gr-1+CD11b+ myeloid derived suppressor cells (MDSCs) are two important components that constitute the tumor microenvironment. Targeting these cells offers the potential to halt tumor growth. In this study, we report a common mediator in C/EBP-δ that regulates both components and aids in tumor development. C/EBP-δ is elevated in tumor derived MDSCs. Interestingly, genetic deletion of C/EBP-δ in mice significantly impaired MDSC expansion in response to tumor progression, but it had no effect on Gr-1+CD11b+ cell production in normal development. It suggests a specific role of C/EBP-δ in emergency myelopoiesis under tumor conditions. Consistent with the pro tumor functions of MDSCs, loss of C/EBP-δ resulted in reduced tumor angiogenesis and tumor growth. Moreover, we found expression of C/EBP-δ in vascular endothelial cells. C/EBP-δ regulated cell motility, endothelial network formation and vascular sprouting. Notably, inactivation of C/EBP-δ in endothelial cells specifically inhibited the expression of VEGFR2 but not VEGFR1. Ectopic expression of C/EBP-δ increased and knockdown of the gene decreased VEGFR2 expression. C/EBP-δ is recruited to the promoter region of VEGFR2, indicative of transcriptional regulation. Collectively, this study has identified a positive mediator in C/EBP-δ, which regulates tumor induced MDSC expansion and VEGFR2 expression in endothelium. Considering the importance of MDSCs and endothelial cells in tumor progression, targeting C/EBP-δ may provide an interesting means for cancer therapy, killing two birds with one stone.

The Expression of Fibroblast Activation Protein in Clear Cell Renal Cell Carcinomas Is Associated with Synchronous Lymph Node Metastases

Clear cell renal cell carcinoma (CCRCC) is a heterogeneous and complex disease that frequently develops distant metastases. Fibroblast activation protein (FAP) is a serine peptidase the expression of which in cancer-associated fibroblasts has been associated with higher risk of metastases and poor survival. The objective of this study was to evaluate the role of FAP in metastatic CCRCC (mCCRCC). A series of 59 mCCRCC retrospectively collected was included in the study. Metastases developed either synchronous (n = 14) or metachronous to renal disease (n = 45). Tumor specimens were obtained from both primary lesion (n = 59) and metastases (n = 54) and FAP expression was immunohistochemically analyzed. FAP expression in fibroblasts from primary tumors correlated with FAP expression in the corresponding metastatic lesions. Also, primary and metastatic FAP expression was correlated with large tumor diameter (>7cm), high grade (G3/4), high stage (pT3/4), tumor necrosis and sarcomatoid transformation. The expression of FAP in primary tumors and in their metastases was associated both with synchronous metastases and also with metastases to the lymph nodes. FAP expression in the primary tumor was correlated with worse 10-year overall survival. Immunohistochemical detection of FAP in the stromal tumor fibroblasts could be a biomarker of early lymph node metastatic status and therefore could account for the poor prognosis of FAP positive CCRCC.

Fibroblast activation protein predicts prognosis in clear cell renal cell carcinoma

Clear cell renal cell carcinoma is a complex disease with only partial response to therapy and scarce reliable clinical parameters indicative of progression and survival. Fibroblast activation protein expression has been correlated with prognosis in several malignancies but never in renal cancer. We aim to analyze the immunohistochemical expression of fibroblast activation protein in 208 clear cell renal cell carcinomas and to evaluate its impact on the prognosis and survival. A positive cytoplasmic immunostaining of this protein in the stromal fibroblasts associated to cancer cells is associated with large tumor diameter (≥4cm), high-grade (G3/4) tumors, and high-stage (≥pT3) tumors. Fibroblast activation protein-positive cases had significantly shorter survivals after 5 (P=.00015), 10 (P=.0000042), and 15 (P=.000043) years of follow-up, with a hazard ratio of 0.31. Multivariate analysis showed that fibroblast activation protein (P=.00117) was stronger than grade and stage in predicting clinical aggressiveness in clear cell renal cell carcinoma. This study confirms the usefulness of fibroblast activation protein detection in the stromal fibroblast associated to cancer in clear cell renal cell carcinoma and adds a new immunohistochemical marker to predict clinical behavior in these patients.

A multi-antigen vaccine in combination with an immunotoxin targeting tumor-associated fibroblast for treating murine melanoma

A therapeutically effective cancer vaccine must generate potent antitumor immune responses and be able to overcome tolerance mechanisms mediated by the progressing tumor itself. Previous studies showed that glycoprotein 100 (gp100), tyrosinase-related protein 1 (TRP1), and tyrosinase-related protein 2 (TRP2) are promising immunogens for melanoma immunotherapy. In this study, we administered these three melanoma-associated antigens via lentiviral vectors (termed LV-3Ag) and found that this multi-antigen vaccine strategy markedly increased functional T-cell infiltration into tumors and generated protective and therapeutic antitumor immunity. We also engineered a novel immunotoxin, αFAP-PE38, capable of targeting fibroblast activation protein (FAP)-expressing fibroblasts within the tumor stroma. When combined with αFAP-PE38, LV-3Ag exhibited greatly enhanced antitumor effects on tumor growth in an established B16 melanoma model. The mechanism of action underlying this combination treatment likely modulates the immune suppressive tumor microenvironment and, consequently, activates cytotoxic CD8⁺ T cells capable of specifically recognizing and destroying tumor cells. Taken together, these results provide a strong rationale for combining an immunotoxin with cancer vaccines for the treatment of patients with advanced cancer.

Adoptive Cellular Therapy (ACT) for Cancer Treatment

Adoptive cellular therapy (ACT) with various lymphocytes or antigen-presenting cells is one stone in the pillar of cancer immunotherapy, which relies on the tumor-specific T cell. The transfusion of bulk T-cell population into patients is an effective treatment for regression of cancer. In this chapter, we summarize the development of various strategies in ACT for cancer immunotherapy and discuss some of the latest progress and obstacles in technical, safety, and even regulatory aspects to translate these technologies to the clinic. ACT is becoming a potentially powerful approach to cancer treatment. Further experiments and clinical trials are needed to optimize this strategy.

CAR-T Cell Therapy for Lymphoma

Lymphomas arise from clonal expansions of B, T, or NK cells at different stages of differentiation. Because they occur in the immunocyte-rich lymphoid tissues, they are easily accessible to antibodies and cell-based immunotherapy. Expressing chimeric antigen receptors (CARs) on T cells is a means of combining the antigen-binding site of a monoclonal antibody with the activating machinery of a T cell, enabling antigen recognition independent of major histocompatibility complex restriction, while retaining the desirable antitumor properties of a T cell. Here, we discuss the basic design of CARs and their potential advantages and disadvantages over other immune therapies for lymphomas. We review current clinical trials in the field and consider strategies to improve the in vivo function and safety of immune cells expressing CARs. The ultimate driver of CAR development and implementation for lymphoma will be the demonstration of their ability to safely and cost-effectively cure these malignancies.

Role of mesenchymal stem cells in osteosarcoma and metabolic reprogramming of tumor cells

The tumor microenvironment plays an important role in cancer progression. Here, we focused on the role of reactive mesenchymal stem cells (MSC) in osteosarcoma (OS), and used human adipose MSC and a panel of OS cell lines (Saos-2, HOS, and 143B) to investigate the mutual effect of normal-cancer cell metabolic programming. Our results showed that MSC are driven by oxidative stress induced by OS cells to undergo Warburg metabolism, with increased lactate production. Therefore, we analyzed the expression of lactate monocarboxylate transporters. By real time PCR and immunofluorescence, in MSC we detected the expression of MCT-4, the transporter for lactate efflux, whereas MCT-1, responsible for lactate uptake, was expressed in OS cells. In agreement, silencing of MCT-1 by siRNA significantly affected the ATP production in OS cancer cells. Thus, cancer cells directly increase their mitochondrial biogenesis using this energy-rich metabolite that is abundantly provided by MSC as an effect of the altered microenvironmental conditions induced by OS cells. We also showed that lactate produced by MSC promotes the migratory ability of OS cells. These data provide novel information to be exploited for cancer therapies targeting the mutual metabolic reprogramming of cancer cells and their stroma.

Cancer-associated fibroblasts: a multifaceted driver of breast cancer progression

Cancerous tissue is a complex mix of tumor cells, stromal cells and extracellular matrix (ECM), all of which make up a disordered and aggressive niche in comparison with organized and homeostatic normal tissue. It is well accepted that the tumor microenvironment plays an indispensable role in cancer development, and thus can be recognized as an additional cancer hallmark alongside those that are well established. In breast cancer, cancer associated fibroblasts (CAFs) are the predominant cellular components and play a centric role in the tumor microenvironment since they not only promote cancer initiation, growth, invasion, metastasis and therapeutic resistance but are also involved in microenvironmental events including angiogenesis/lymphangiogenesis, ECM remodeling, cancer-associated inflammation and metabolism reprogramming, all of which are known to have pre-malignancy potency. At the molecular level, there is a sophisticated network underlying the interactions between CAFs and epithelial cells as well as other stromal components. Accordingly, targeting CAFs provides a novel strategy in cancer therapy. Herein, we summarize the current understanding of the role of CAFs in breast cancer.

Cancer-associated fibroblasts in digestive tumors

The significant influence of tumor stroma on malignant cells has been extensively investigated in this era of targeted therapy. The tumor microenvironment, as a dynamic system, is orchestrated by various cells including tumor vascular composing cells, inflammatory cells and fibroblasts. As a major and important component in tumor stroma, increasing evidence has shown that spindle-shaped cancer-associated fibroblasts (CAFs) are a significant modifier of cancer evolution, and promote tumorigenesis, tumor invasion and metastasis by stimulating angiogenesis, malignant cell survival, epithelial-mesenchymal transition (EMT) and proliferation via direct cell-to-cell contact or secretion of soluble factors in most digestive solid tumors. CAFs are thought to be activated, characterized by the expression of α-smooth muscle actin, fibroblast activated protein, fibroblast specific protein, vimentin, fibronectin, etc. They are hypothesized to originate from normal or aged fibroblasts, bone marrow-derived mesenchymal cells, or vascular endothelial cells. EMT may also be an important process generating CAFs, and most probably, CAFs may originate from multiple cells. A close link exists between EMT, tumor stem cells, and chemo-resistance of tumor cells, which is largely orchestrated by CAFs. CAFs significantly induce immunosuppression, and may be a prognostic marker in various malignancies. Targeted therapy toward CAFs has displayed promising anticancer efficacy, which further reinforces the necessity to explore the relationship between CAFs and their hosts.

Adoptive immunotherapy for cancer

Recent clinical success has underscored the potential for immunotherapy based on the adoptive cell transfer (ACT) of engineered T lymphocytes to mediate dramatic, potent, and durable clinical responses. This success has led to the broader evaluation of engineered T-lymphocyte-based adoptive cell therapy to treat a broad range of malignancies. In this review, we summarize concepts, successes, and challenges for the broader development of this promising field, focusing principally on lessons gleaned from immunological principles and clinical thought. We present ACT in the context of integrating T-cell and tumor biology and the broader systemic immune response.

Design and development of therapies using chimeric antigen receptor-expressing T cells

Investigators developed chimeric antigen receptors (CARs) for expression on T cells more than 25 years ago. When the CAR is derived from an antibody, the resultant cell should combine the desirable targeting features of an antibody (e.g. lack of requirement for major histocompatibility complex recognition, ability to recognize non-protein antigens) with the persistence, trafficking, and effector functions of a T cell. This article describes how the past two decades have seen a crescendo of research which has now begun to translate these potential benefits into effective treatments for patients with cancer. We describe the basic design of CARs, describe how antigenic targets are selected, and the initial clinical experience with CAR-T cells. Our review then describes our own and other investigators' work aimed at improving the function of CARs and reviews the clinical studies in hematological and solid malignancies that are beginning to exploit these approaches. Finally, we show the value of adding additional engineering features to CAR-T cells, irrespective of their target, to render them better suited to function in the tumor environment, and discuss how the safety of these heavily modified cells may be maintained.

A vaccine that co-targets tumor cells and cancer associated fibroblasts results in enhanced antitumor activity by inducing antigen spreading

Dendritic cell (DC) vaccines targeting only cancer cells have produced limited antitumor activity in most clinical studies. Targeting cancer-associated fibroblasts (CAFs) in addition to cancer cells may enhance antitumor effects, since CAFs, the central component of the tumor stroma, directly support tumor growth and contribute to the immunosuppressive tumor microenvironment. To co-target CAFs and tumor cells we developed a new compound DC vaccine that encodes an A20-specific shRNA to enhance DC function, and targets fibroblast activation protein (FAP) expressed in CAFs and the tumor antigen tyrosine-related protein (TRP)2 (DC-shA20-FAP-TRP2). DC-shA20-FAP-TRP2 vaccination induced robust FAP- and TRP2-specific T-cell responses, resulting in greater antitumor activity in the B16 melanoma model in comparison to monovalent vaccines or a vaccine encoding antigens and a control shRNA. DC-shA20-FAP-TRP2 vaccination enhanced tumor infiltration of CD8-positive T cells, and induced antigen-spreading resulting in potent antitumor activity. Thus, co-targeting of tumor cells and CAFs results in the induction of broad-based tumor-specific T-cell responses and has the potential to improve current vaccine approaches for cancer.

Cancer cell glycocalyx mediates mechanotransduction and flow-regulated invasion

Mammalian cells are covered by a surface proteoglycan (glycocalyx) layer, and it is known that blood vessel-lining endothelial cells use the glycocalyx to sense and transduce the shearing forces of blood flow into intracellular signals. Tumor cells in vivo are exposed to forces from interstitial fluid flow that may affect metastatic potential but are not reproduced by most in vitro cell motility assays. We hypothesized that glycocalyx-mediated mechanotransduction of interstitial flow shear stress is an un-recognized factor that can significantly enhance metastatic cell motility and play a role in augmentation of invasion. Involvement of MMP levels, cell adhesion molecules (CD44, α3 integrin), and glycocalyx components (heparan sulfate and hyaluronan) was investigated in a cell/collagen gel suspension model designed to mimic the interstitial flow microenvironment. Physiological levels of flow upregulated MMP levels and enhanced the motility of metastatic cells. Blocking the flow-enhanced expression of MMP activity or adhesion molecules (CD44 and integrins) resulted in blocking the flow-enhanced migratory activity. The presence of a glycocalyx-like layer was verified around tumor cells, and the degradation of this layer by hyaluronidase and heparinase blocked the flow-regulated invasion. This study shows for the first time that interstitial flow enhancement of metastatic cell motility can be mediated by the cell surface glycocalyx - a potential target for therapeutics.

Antitumor effects of chimeric receptor engineered human T cells directed to tumor stroma

Cancer-associated fibroblasts (CAFs), the principle component of the tumor-associated stroma, form a highly protumorigenic and immunosuppressive microenvironment that mediates therapeutic resistance. Co-targeting CAFs in addition to cancer cells may therefore augment the antitumor response. Fibroblast activation protein-α (FAP), a type 2 dipeptidyl peptidase, is expressed on CAFs in a majority of solid tumors making it an attractive immunotherapeutic target. To target FAP-positive CAFs in the tumor-associated stroma, we genetically modified T cells to express a FAP-specific chimeric antigen receptor (CAR). The resulting FAP-specific T cells recognized and killed FAP-positive target cells as determined by proinflammatory cytokine release and target cell lysis. In an established A549 lung cancer model, adoptive transfer of FAP-specific T cells significantly reduced FAP-positive stromal cells, with a concomitant decrease in tumor growth. Combining these FAP-specific T cells with T cells that targeted the EphA2 antigen on the A549 cancer cells themselves significantly enhanced overall antitumor activity and conferred a survival advantage compared to either alone. Our study underscores the value of co-targeting both CAFs and cancer cells to increase the benefits of T-cell immunotherapy for solid tumors.

Existence of glioma stroma mesenchymal stemlike cells in Korean glioma specimens

PURPOSE

It was presented that mesenchymal stem cells (MSCs) can be isolated from western glioma specimens. However, whether MSCs exist in glioma specimens of different ethnicities is unknown. To verify the existence of MSCs in an independent cohort, we undertook studies to isolate MSCs from a group of Korean patients. We hypothesized that cells resembling MSCs that were deemed mesenchymal stemlike cells (MSLCs) exist in an independent cohort of Korean gliomas.

METHODS

We cultured fresh glioma specimens using the protocols used for culturing MSCs. The cultured cells were analyzed with fluorescence-activated cell sorting (FACS) for surface markers associated with MSCs. Cultured cells were exposed to mesenchymal differentiation conditions. To presume possible locations of MSLCs in the glioma, sections of glioma were analyzed by immunofluorescent labeling for CD105, CD31, and NG2.

RESULTS

From nine of 31 glioma specimens, we isolated cells resembling MSCs, which were deemed Korean glioma stroma MSLCs (KGS-MSLCs). KGS-MSLCs were spindle shaped and adherent to plastic. KGS-MSLCs had similar surface markers to MSCs (CD105(+), CD90(+), CD73(+), and CD45(-)). KGS-MSLCs were capable of mesenchymal differentiation and might be located around endothelial cells, pericytes, and in a disorganized perivascular area inside glioma stroma.

CONCLUSIONS

We found that cells resembling MSCs indeed exist in an independent cohort of glioma patients, as presented in western populations. We could presume that the possible location of KGS-MSLCs was in perivascular area or in glioma stroma that was a disorganized vascular niche. It might be possible that KGS-MSLCs could be one of constituent of stroma of glioma microenvironment.

Psychoneuroimmunology and cancer: a decade of discovery, paradigm shifts, and methodological innovations

This article introduces the supplement Advances in Cancer and Brain, Behavior, and Immunity and outlines important discoveries, paradigm shifts, and methodological innovations that have emerged in the past decade to advance mechanistic and translational understanding of biobehavioral influences on tumor biology, cancer treatment-related sequelae, and cancer outcomes. We offer a heuristic framework for research on biobehavioral pathways in cancer. The shifting survivorship landscape is highlighted, and we propose that the changing demographics suggest prudent adoption of a life course perspective of cancer and cancer survivorship. We note opportunities for psychoneuroimmunology (PNI) research to ameliorate the long-term, unintended consequences of aggressive curative intent and call attention to the critical role of reciprocal translational pathways between animal and human studies. Lastly, we briefly summarize the articles included in this compilation and offer our perspectives on future research directions.

Tumor endothelial inflammation predicts clinical outcome in diverse human cancers

BACKGROUND

Vascular endothelial cells contribute to the pathogenesis of numerous human diseases by actively regulating the stromal inflammatory response; however, little is known regarding the role of endothelial inflammation in the growth of human tumors and its influence on the prognosis of human cancers.

METHODS

Using an experimental model of tumor necrosis factor-alpha (TNF-α)-mediated inflammation, we characterized inflammatory gene expression in immunopurified tumor-associated endothelial cells. These genes formed the basis of a multivariate molecular predictor of overall survival that was trained and validated in four types of human cancer.

RESULTS

We report that expression of experimentally derived tumor endothelial genes distinguished pathologic tissue specimens from normal controls in several human diseases associated with chronic inflammation. We trained these genes in human cancer datasets and defined a six-gene inflammatory signature that predicted significantly reduced overall survival in breast cancer, colon cancer, lung cancer, and glioma. This endothelial-derived signature predicted outcome independently of, but cooperatively with, standard clinical and pathological prognostic factors. Consistent with these findings, conditioned culture media from human endothelial cells stimulated by pro-inflammatory cytokines accelerated the growth of human colon and breast tumors in immunodeficient mice as compared with conditioned media from untreated endothelial cells.

CONCLUSIONS

This study provides the first prognostic cancer gene signature derived from an experimental model of tumor-associated endothelial inflammation. These findings support the notion that activation of inflammatory pathways in non-malignant tumor-infiltrating endothelial cells contributes to tumor growth and progression in multiple human cancers. Importantly, these results identify endothelial-derived factors that could serve as potential targets for therapy in diverse human cancers.

Effect of mesenchymal stem cells on hypoxia-induced desensitization of β2-adrenergic receptors in rat osteosarcoma cells

The β2-adrenergic receptor (β2AR) mediates the effects of chronic stress in several neoplasms, however, β2AR signaling is impaired by hypoxia in various tissues. While hypoxia is a common feature significant in the progression of solid tumors, little is known about the effect of hypoxia on β2AR signaling in the tumor microenvironment. Previously, it has been reported that the systemic administration of mesenchymal stem cells (MSCs) increased the engraftment and metastatic colonization of rat osteosarcoma (OS) cells. In the current study, the effect of MSCs on the hypoxia-induced desensitization of the β2AR in OS cells was investigated. Epinephrine, norepinephrine and isoproterenol increased the cellular proliferation of the rat OS cell line COS1NR and rat MSCs in a dose-dependent and β2AR antagonist-sensitive manner. While isoproterenol had significant proliferative effects on MSCs under normoxic and hypoxic conditions, COS1NR cells did not respond under hypoxic conditions. A sensitivity assay for the β2AR revealed that hypoxia impaired the sensitivity of COS1NR cells, whereas hypoxia did not affect MSCs. An immunoassay revealed no significant change in the expression of hypoxia-inducible factor-1α (HIF1α) in COS1NR cells, whilst an immunoassay demonstrated a 15% increase in MSCs following isoproterenol stimulation. In COS1NR cells co-cultured with MSCs under hypoxic conditions, isoproterenol caused a significant increase in proliferation and this effect was inhibited by an anti-interleukin (IL)-6 antibody. A tumor formation assay in syngeneic rats revealed that the systemic administration of MSCs enhances the growth of OS and the effect of MSCs was inhibited by IL-6 neutralization. In conclusion, MSCs are resistant to the hypoxia-induced desensitization to β2AR. Hypoxia caused a siginificant desensitization of the β2AR in COS1NR cells alone, whereas MSCs may support tumor progression through cellular interactions.

Hepatocellular carcinoma-associated fibroblasts trigger NK cell dysfunction via PGE2 and IDO

Defects in natural killer (NK) cell function are necessary for tumor immune escape, but the underlying regulatory mechanisms in human cancers remain largely unknown. Here we show that fibroblasts derived from hepatocellular carcinoma (HCC) were significantly superior to foreskin-derived fibroblasts at inducing NK cell dysfunction, which is characterized by low expression of cytotoxic molecules and surface markers for cell activation, impaired production of cytokines, and decreased cytotoxicity against K562 cells in vitro. Our results also indicate that PGE2 and IDO, derived from activated fibroblasts, suppress the activation of NK cells and thereby create favorable conditions for tumor progression.

Impact of novel oncolytic virus HF10 on cellular components of the tumor microenviroment in patients with recurrent breast cancer

Oncolytic viruses are a promising method of cancer therapy, even for advanced malignancies. HF10, a spontaneously mutated herpes simplex type 1, is a potent oncolytic agent. The interaction of oncolytic herpes viruses with the tumor microenvironment has not been well characterized. We injected HF10 into tumors of patients with recurrent breast carcinoma, and sought to determine its effects on the tumor microenvironment. Six patients with recurrent breast cancer were recruited to the study. Tumors were divided into two groups: saline-injected (control) and HF10-injected (treatment). We investigated several parameters including neovascularization (CD31) and tumor lymphocyte infiltration (CD8, CD4), determined by immunohistochemistry, and apoptosis, determined by terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Median apoptotic cell count was lower in the treatment group (P=0.016). Angiogenesis was significantly higher in treatment group (P=0.032). Count of CD8-positive lymphocytes infiltrating the tumors was higher in the treatment group (P=0.008). We were unable to determine CD4-positive lymphocyte infiltration. An effective oncolytic viral agent must replicate efficiently in tumor cells, leading to higher viral counts, in order to aid viral penetration. HF10 seems to meet this criterion; furthermore, it induces potent antitumor immunity. The increase in angiogenesis may be due to either viral replication or the inflammatory response.

The impact of adhesion peptides within hydrogels on the phenotype and signaling of normal and cancerous mammary epithelial cells

The microenviroment contributes to directing mammary epithelial cell (MEC) development and the progression of breast cancer. Three-dimensional culture models have been used to support formation of structures that display varying degrees of disorganization that parallel the degree of cancer. Synthetic hydrogels were employed to investigate the mechanisms by which specific adhesion signals in the microenvironment directed development. Polyethylene glycol-based hydrogels supported 3D growth of MECs and directed formation of a range of phenotypes that were functions of genotype, and identity and concentration of adhesion peptides RGD and YIGSR. Non-cancerous and cancerous MECs responded differentially to the same adhesion cues and produced variable structural organizations. An analysis of dynamic signaling pathways revealed differential activities of transcription factors within the MAPK and JAK/STAT pathways in response to genotype and adhesion. These results directly implicate adhesion in cancer development and demonstrate that AP1, CREB, STAT1, and STAT3 all contribute to the genotype dependence of cellular response to adhesion peptides. The tools presented in this work could be applied to other systems and connect extracellular cues with intracellular signaling to molecularly dissect tissue development and further biomaterials development.

Tumor heterogeneity: mechanisms and bases for a reliable application of molecular marker design

Tumor heterogeneity is a confusing finding in the assessment of neoplasms, potentially resulting in inaccurate diagnostic, prognostic and predictive tests. This tumor heterogeneity is not always a random and unpredictable phenomenon, whose knowledge helps designing better tests. The biologic reasons for this intratumoral heterogeneity would then be important to understand both the natural history of neoplasms and the selection of test samples for reliable analysis. The main factors contributing to intratumoral heterogeneity inducing gene abnormalities or modifying its expression include: the gradient ischemic level within neoplasms, the action of tumor microenvironment (bidirectional interaction between tumor cells and stroma), mechanisms of intercellular transference of genetic information (exosomes), and differential mechanisms of sequence-independent modifications of genetic material and proteins. The intratumoral heterogeneity is at the origin of tumor progression and it is also the byproduct of the selection process during progression. Any analysis of heterogeneity mechanisms must be integrated within the process of segregation of genetic changes in tumor cells during the clonal expansion and progression of neoplasms. The evaluation of these mechanisms must also consider the redundancy and pleiotropism of molecular pathways, for which appropriate surrogate markers would support the presence or not of heterogeneous genetics and the main mechanisms responsible. This knowledge would constitute a solid scientific background for future therapeutic planning.

Determination of serum CRP, VEGF, Leptin, CK-MB, CA-15-3 and IL-6 levels for malignancy prediction in adnexal masses

OBJECTIVE

Investigation of serum markers which could be used in the malignancy prediction of adnexal masses.

MATERIAL AND METHODS

Vascular endothelial growth factor (VEGF), interleukin 6 (IL-6), leptin, C-reactive protein (CRP), creatine-kinase-MB (CK-MB) and cancer antigen 15-3 (CA 15-3) levels were determined prospectively in serum samples that were obtained from patients who underwent surgery for an adnexal mass and who were referred to Istanbul University, Faculty of Medicine, Department of Obstetrics and Gynecology, between 2009 and 2011, and then were compared with the serum samples of completely healthy outpatient patients as a control group. Based onto the ovarian cancer status, cases were divided into four groups: 13 patients were included in the early-stage malignant group, 12 patients were included in the advanced-stage malignant group, 25 in the benign group and 19 in the healthy control group. Patients with only epithelial ovarian cancer were included into the cancer group. Ethics Commitee approval was obtained for this study. The budget was supported by the Istanbul University Scientific Research Projects Unit.

RESULTS

RESULTS RELATED WITH SENSITIVITY, SPECIFICITY, POSITIVE PREDICTIVE VALUE (PPV), NEGATIVE PREDICTIVE VALUE (NPV) AND ODDS RATIO (OR), RESPECTIVELY, AND THE FOLLOWING VALUES WERE CALCULATED: 48%, 95%, 92%, 59% and +OR 9.6 -OR 0.5 for CA; 15-3; 52%, 75%, 72%, 55%, +OR 2.08 -OR 0.64 for leptin; 72%, 70%, 75%, 66% 2.4-0.5 for IL-6; 24%, 80%, 60%, 45%, 1.2-0.92 for VEGF; 68%, 30%, 55%, 43%, 0.97-1.06 for CRP; and 8%, 70%, 25%, 38%, 026-1.31 for CK-MB.

CONCLUSION

CA 15-3, IL-6, Leptin, VEGF and CRP were effective in the prediction of benign and malignant masses; however they may be more suitable in selected cases as they have a limited use because of their inadequate potential regarding sensitivity and specificity.

Presence of glioma stroma mesenchymal stem cells in a murine orthotopic glioma model

PURPOSE

High-grade gliomas are closely related to the mesenchymal phenotype which might be explained by unorthodox differentiation of glioma cancer stem cells (gCSCs). We reasoned that other non-neural stem cells, especially mesenchymal stem cells (MSCs), might play a role in expressing mesenchymal phenotype of high-grade gliomas. Thus we hypothesized that cells resembling MSCs exist in glioma specimens.

METHODS

We created a mouse (m) orthotopic glioma model using human gCSCs. Single-cell suspensions were isolated from glioma specimens and cultured according to the methods for mMSCs or gliomaspheres. These cells were analyzed by fluorescence-activated cell sorting (FACS) for surface markers associated with mMSCs or gCSCs. Glioma stroma (GS)-MSCs were exposed to mesenchymal differentiation conditions. To decide the location of GS-MSCs, sections of orthotopic glioma models were analyzed by immunofluorescent labeling.

RESULTS

GS-MSCs were isolated which were morphologically similar to mMSCs. FACS analysis showed that the GS-MSCs had similar surface markers to mMSCs (stem cell antigen-1 [Sca-1](+), CD9(+), CD45(-), CD11b(-), CD31(-), and nerve/glial antigen 2 [NG2](-)). GS-MSCs were capable of mesenchymal differentiation. Immunofluorescent labeling indicated that GS-MSCs are located around blood vessels, are distinct from endothelial cells, and have features that partially overlap with vascular pericytes.

CONCLUSIONS

Our results indicate that cells similar to mMSCs exist in glioma specimens. The GS-MSCs might be located around vessels, which suggests that GS-MSCs may provide the mesenchymal elements of the vascular niche. GS-MSCs may represent non-neural stem cells that act as an important source of mesenchymal elements, particularly during the growth of gliomas.

Fluid shear stress regulates the invasive potential of glioma cells via modulation of migratory activity and matrix metalloproteinase expression

Background

Glioma cells are exposed to elevated interstitial fluid flow during the onset of angiogenesis, at the tumor periphery while invading normal parenchyma, within white matter tracts, and during vascular normalization therapy. Glioma cell lines that have been exposed to fluid flow forces in vivo have much lower invasive potentials than in vitro cell motility assays without flow would indicate.

Methodology/Principal Findings

A 3D Modified Boyden chamber (Darcy flow through collagen/cell suspension) model was designed to mimic the fluid dynamic microenvironment to study the effects of fluid shear stress on the migratory activity of glioma cells. Novel methods for gel compaction and isolation of chemotactic migration from flow stimulation were utilized for three glioma cell lines: U87, CNS-1, and U251. All physiologic levels of fluid shear stress suppressed the migratory activity of U87 and CNS-1 cell lines. U251 motility remained unaltered within the 3D interstitial flow model. Matrix Metalloproteinase (MMP) inhibition experiments and assays demonstrated that the glioma cells depended on MMP activity to invade, and suppression in motility correlated with downregulation of MMP-1 and MMP-2 levels. This was confirmed by RT-PCR and with the aid of MMP-1 and MMP-2 shRNA constructs.

Conclusions/Significance

Fluid shear stress in the tumor microenvironment may explain reduced glioma invasion through modulation of cell motility and MMP levels. The flow-induced migration trends were consistent with reported invasive potentials of implanted gliomas. The models developed for this study imply that flow-modulated motility involves mechanotransduction of fluid shear stress affecting MMP activation and expression. These models should be useful for the continued study of interstitial flow effects on processes that affect tumor progression.

Anti-leukemic therapies induce cytogenetic changes of human bone marrow-derived mesenchymal stem cells

Both bone marrow hematopoietic cells (BM-HCs) and mesenchymal stem cells (BM-MSCs) may have cytogenetic aberrations in leukemic patients, and anti-leukemic therapy may induce cytogenetic remission of BM-HCs. The impact of anti-leukemic therapy on BM-MSCs remains unknown. Cytogenetic studies of BM-MSCs from 15 leukemic patients with documented cytogenetic abnormalities of BM-HCs were investigated. To see the influence of anti-leukemic therapy on BM-MSCs, cytogenetic studies were carried out in seven of them after the completion of anti-leukemic therapy, including anthracycline/Ara-C-based chemotherapy in two patients, high-dose busulfan/cyclophosphamide-based allogeneic transplantation in two patients, and total body irradiation (TBI)-based allogeneic transplantation in three patients. To simulate the effect of TBI in vitro, three BM-MSCs from one leukemic patient and two normal adults were irradiated using the same dosage and dosing schedule of TBI and cytogenetics were re-examined after irradiation. At the diagnosis of leukemia, two BM-MSCs had cytogenetic aberration, which were completely different to their BM-HCs counterpart. After the completion of anti-leukemic therapy, cytogenetic aberration was no longer detectable in one patient. Unexpectedly, BM-MSCs from three patients receiving TBI-based allogeneic transplantation acquired new, clonal cytogenetic abnormalities after transplantation. Similarly, complex cytogenetic abnormalities were found in all the three BM-MSCs exposed to in vitro irradiation. In conclusion, anti-leukemic treatments induce not only "cytogenetic remission" but also new cytogenetic abnormalities of BM-MSCs. TBI especially exerts detrimental effect on the chromosomal integrity of BM-MSCs and highlights the equal importance of investigating long-term adverse effect of anti-leukemic therapy on BM-MSCs as opposed to beneficial effect on BM-HCs.

Invasive three-dimensional organotypic neoplasia from multiple normal human epithelia

Refined cancer models are required if researchers are to assess the burgeoning number of potential targets for cancer therapeutics in a clinically relevant context that allows a fast turnaround. Here we use tumor-associated genetic pathways to transform primary human epithelial cells from the epidermis, oropharynx, esophagus and cervix into genetically defined tumors in a human three-dimensional (3D) tissue environment that incorporates cell-populated stroma and intact basement membrane. These engineered organotypic tissues recapitulated natural features of tumor progression, including epithelial invasion through basement membrane, a complex process that is necessary for biological malignancy in 90% of human cancers. Invasion was rapid and was potentiated by stromal cells. Oncogenic signals in 3D tissue, but not 2D culture, resembled gene expression profiles from spontaneous human cancers. We screened 3D organotypic neoplasia with well-characterized signaling pathway inhibitors to distill a clinically faithful cancer gene signature. Multitissue 3D human tissue cancer models may provide an efficient and relevant complement to current approaches to characterizing cancer progression.

Tumour stromal cells derived from paediatric malignancies display MSC-like properties and impair NK cell cytotoxicity

Background

Tumour growth and metastatic infiltration are favoured by several components of the tumour microenvironment. Bone marrow-derived multipotent mesenchymal stromal cells (MSC) are known to contribute to the tumour stroma. When isolated from healthy bone marrow, MSC exert potent antiproliferative effects on immune effector cells. Due to phenotypic and morphological similarities of MSC and tumour stromal cells (TStrC), we speculated that immunotherapeutic approaches may be hampered if TStrC may still exhibit immunomodulatory properties of MSC.

Methods

In order to compare immunomodulatory properties of MSC and tumour stromal cells (TStrC), we established and analyzed TStrC cultures from eleven paediatric tumours and MSC preparations from bone marrow aspirates. Immunophenotyping, proliferation assays and NK cell cytotoxicity assays were employed to address the issue.

Results

While TStrC differed from MSC in terms of plasticity, they shared surface expression of CD105, CD73 and other markers used for MSC characterization. Furthermore, TStrC displayed a strong antiproliferative effect on peripheral blood mononuclear cells (PBMC) in coculture experiments similar to MSC. NK cell cytotoxicity was significantly impaired after co-culture with TStrC and expression of the activating NK cell receptors NKp44 and NKp46 was reduced.

Conclusions

Our data show that TStrC and MSC share important phenotypic and functional characteristics. The inhibitory effect of TStrC on PBMC and especially on NK cells may facilitate the immune evasion of paediatric tumours.

Bone marrow stromal cells from multiple myeloma patients uniquely induce bortezomib resistant NF-kappaB activity in myeloma cells

BACKGROUND

Components of the microenvironment such as bone marrow stromal cells (BMSCs) are well known to support multiple myeloma (MM) disease progression and resistance to chemotherapy including the proteasome inhibitor bortezomib. However, functional distinctions between BMSCs in MM patients and those in disease-free marrow are not completely understood. We and other investigators have recently reported that NF-kappaB activity in primary MM cells is largely resistant to the proteasome inhibitor bortezomib, and that further enhancement of NF-kappaB by BMSCs is similarly resistant to bortezomib and may mediate resistance to this therapy. The mediating factor(s) of this bortezomib-resistant NF-kappaB activity is induced by BMSCs is not currently understood.

RESULTS

Here we report that BMSCs specifically derived from MM patients are capable of further activating bortezomib-resistant NF-kappaB activity in MM cells. This induced activity is mediated by soluble proteinaceous factors secreted by MM BMSCs. Among the multiple factors evaluated, interleukin-8 was secreted by BMSCs from MM patients at significantly higher levels compared to those from non-MM sources, and we found that IL-8 contributes to BMSC-induced NF-kappaB activity.

CONCLUSIONS

BMSCs from MM patients uniquely enhance constitutive NF-kappaB activity in MM cells via a proteinaceous secreted factor in part in conjunction with IL-8. Since NF-kappaB is known to potentiate MM cell survival and confer resistance to drugs including bortezomib, further identification of the NF-kappaB activating factors produced specifically by MM-derived BMSCs may provide a novel biomarker and/or drug target for the treatment of this commonly fatal disease.

Cancer stem cells in lung tumorigenesis

Although stem cells were discovered more than 50 years ago, we have only recently begun to understand their potential importance in cancer biology. Recent advances in our ability to describe, isolate, and study lung stem cell populations has led to a growing recognition of the central importance cells with stem cell-like properties may have in lung tumorigenesis. This article reviews the major studies supporting the existence and importance of cancer stem cells in lung tumorigenesis. Continued research in the field of lung cancer stem cell biology is vital, as ongoing efforts promise to yield new prognostic and therapeutic targets.

Innovative immunohistochemistry identifies MMP-9 expressing macrophages at the invasive front of murine HCC

AIM

To investigate the proteolytic contribution of tumor-associated macrophages (TAM) in tumor invasion, we analyzed whether TAM at the invasive front of small HCC in Abcb4(-/-)-mice show an enhanced expression of MMP-9.

METHODS

Liver cryosections of the hepatocellular carcinoma (HCC) invasive front from 12 mo old Abcb4(-/-)-mice were stained for collagen type I and MMP-9 using Alexa488 and Alexa568 labeled secondary antibodies. Afterwards, the Alexa568 dye was bleached and the macrophage marker F4/80 was visualized using Alexa568 labeled secondary antibodies. Finally, photographs of the invasive tumor front were digitally overlaid and analyzed.

RESULTS

After complete bleaching of the primary dye, specific fluorescence staining of a third antigen, here F4/80, was successfully performed on the same histological section. With this method, we were able to identify conglomerates of matrix metalloproteinase (MMP-9) expressing macrophages within the tumor capsule of HCC.

CONCLUSION

MMP-9 expressing macrophages are involved in matrix remodelling at the invasive tumor front of HCC. The described staining protocol provides a simple yet powerful extension of conventional immuno-histochemistry, facilitating visualization of at least three different antigens plus nuclei in one single histological section.

Impact of tumor microenvironment on oncolytic viral therapy

Interactions between tumor cells and their microenvironment have been shown to play a very significant role in the initiation, progression, and invasiveness of cancer. These tumor-stromal interactions are capable of altering the delivery and effectiveness of therapeutics into the tumor and are also known to influence future resistance and re-growth after treatment. Here we review recent advances in the understanding of the tumor microenvironment and its response to oncolytic viral therapy. The multifaceted environmental response to viral therapy can influence viral infection, replication, and propagation within the tumor. Recent studies have unveiled the complicated temporal changes in the tumor vasculature post-oncolytic virus (OV) treatment, and their impact on tumor biology. Similarly, the secreted extracellular matrix in solid tumors can affect both infection and spread of the therapeutic virus. Together, these complex changes in the tumor microenvironment also modulate the activation of the innate antiviral host immune response, leading to quick and efficient viral clearance. In order to combat these detrimental responses, viruses have been combined with pharmacological adjuvants and "armed" with therapeutic genes in order to suppress the pernicious environmental conditions following therapy. In this review we will discuss the impact of the tumor environment on viral therapy and examine some of the recent literature investigating methods of modulating this environment to enhance oncolysis.