Functional investigation of NCI-H460-inducible myofibroblasts on the chemoresistance to VP-16 with a microfluidic 3D co-culture device

Apoptosis Deregulation and the Development of Cancer Multi-Drug Resistance

Simple Summary

Despite recent therapeutic advances against cancer, many patients do not respond well or respond poorly, to treatment and develop resistance to more than one anti-cancer drug, a term called multi-drug resistance (MDR). One of the main factors that contribute to MDR is the deregulation of apoptosis or programmed cell death. Herein, we describe the major apoptotic pathways and discuss how pro-apoptotic and anti-apoptotic proteins are modified in cancer cells to convey drug resistance. We also focus on our current understanding related to the interactions between survival and cell death pathways, as well as on mechanisms underlying the balance shift towards cancer cell growth and drug resistance. Moreover, we highlight the role of the tumor microenvironment components in blocking apoptosis in MDR tumors, and we discuss the significance and potential exploitation of epigenetic modifications for cancer treatment. Finally, we summarize the current and future therapeutic approaches for overcoming MDR.

Abstract

The ability of tumor cells to evade apoptosis is established as one of the hallmarks of cancer. The deregulation of apoptotic pathways conveys a survival advantage enabling cancer cells to develop multi-drug resistance (MDR), a complex tumor phenotype referring to concurrent resistance toward agents with different function and/or structure. Proteins implicated in the intrinsic pathway of apoptosis, including the Bcl-2 superfamily and Inhibitors of Apoptosis (IAP) family members, as well as their regulator, tumor suppressor p53, have been implicated in the development of MDR in many cancer types. The PI₃K/AKT pathway is pivotal in promoting survival and proliferation and is often overactive in MDR tumors. In addition, the tumor microenvironment, particularly factors secreted by cancer-associated fibroblasts, can inhibit apoptosis in cancer cells and reduce the effectiveness of different anti-cancer drugs. In this review, we describe the main alterations that occur in apoptosis-and related pathways to promote MDR. We also summarize the main therapeutic approaches against resistant tumors, including agents targeting Bcl-2 family members, small molecule inhibitors against IAPs or AKT and agents of natural origin that may be used as monotherapy or in combination with conventional therapeutics. Finally, we highlight the potential of therapeutic exploitation of epigenetic modifications to reverse the MDR phenotype.

The Tumor-on-Chip: Recent Advances in the Development of Microfluidic Systems to Recapitulate the Physiology of Solid Tumors

The ideal in vitro recreation of the micro-tumor niche-although much needed for a better understanding of cancer etiology and development of better anticancer therapies-is highly challenging. Tumors are complex three-dimensional (3D) tissues that establish a dynamic cross-talk with the surrounding tissues through complex chemical signaling. An extensive body of experimental evidence has established that 3D culture systems more closely recapitulate the architecture and the physiology of human solid tumors when compared with traditional 2D systems. Moreover, conventional 3D culture systems fail to recreate the dynamics of the tumor niche. Tumor-on-chip systems, which are microfluidic devices that aim to recreate relevant features of the tumor physiology, have recently emerged as powerful tools in cancer research. In tumor-on-chip systems, the use of microfluidics adds another dimension of physiological mimicry by allowing a continuous feed of nutrients (and pharmaceutical compounds). Here, we discuss recently published literature related to the culture of solid tumor-like tissues in microfluidic systems (tumor-on-chip devices). Our aim is to provide the readers with an overview of the state of the art on this particular theme and to illustrate the toolbox available today for engineering tumor-like structures (and their environments) in microfluidic devices. The suitability of tumor-on-chip devices is increasing in many areas of cancer research, including the study of the physiology of solid tumors, the screening of novel anticancer pharmaceutical compounds before resourcing to animal models, and the development of personalized treatments. In the years to come, additive manufacturing (3D bioprinting and 3D printing), computational fluid dynamics, and medium- to high-throughput omics will become powerful enablers of a new wave of more sophisticated and effective tumor-on-chip devices.

M2 macrophages promote NSCLC metastasis by upregulating CRYAB

The mechanism by which tumor-associated macrophages (TAMs) affect cancer progression is not fully understood. This study developed a microfluidic-based co-culture device to mimic the tumor microenvironment to assess TAM effects on invasion and metastasis in NSCLC. The results showed lung carcinoma cells could cause macrophages to show the M2 (a TAM-like) phenotype, and these M2 macrophages promoted lung cancer cell EMT and invasion. Proteomic analysis by the iTRAQ quantitation strategy and GO ontology of the cancer cells indicated that αB-Crystallin (CRYAB) might be involved in this process. Further, we confirmed the role of CRYAB in cancer invasion and metastasis through cell and animal experiments, as well as human cancer tissue assessment. Overall, we demonstrated that M2 macrophages promote malignancy in lung cancer through the EMT by upregulating CRYAB expression and activating the ERK1/2/Fra-1/slug signaling pathway.

Pre-clinical Models for Studying the Interaction Between Mesenchymal Stromal Cells and Cancer Cells and the Induction of Stemness

Mesenchymal stromal cells (MSC) have essential functions in building and supporting the tumour microenvironment, providing metastatic niches, and maintaining cancer hallmarks, and it is increasingly evident that the study of the role of MSC in cancer is crucial for paving the way to clinical opportunities for novel anti-cancer therapies. To date, the vast majority of preclinical models that have been used for studying the effect of reactive MSC on cancer growth, metastasis, and response to therapy has been mainly based on in vitro flat biology, including the co-culturing with cell compartmentalization or with cell-to-cell contact, and on in vivo cancer models with different routes of MSC inoculation. More complex in vitro 3D models based on spheroid structures that are formed by intermingled MSC and tumour cells are also capturing the interest in cancer research. These are innovative culture systems tailored on the specific tumour type and that can be combined with a synthetic extracellular matrix, or included in in silico technologies, to more properly mimic the in vivo biological, spatial, biochemical, and biophysical features of tumour tissues. In this review, we summarized the most popular and currently available preclinical models for evaluating the role of MSC in cancer and their specific suitability, for example, in assaying the MSC-driven induction of epithelial-to-mesenchymal transition or of stem-like traits in cancer cells. Finally, we enlightened the need to carefully consider those parameters that might unintentionally strongly affect the secretome in MSC-cancer interplay and introduce confounding variables for the interpretation of results.

In Situ Analysis of Interactions between Fibroblast and Tumor Cells for Drug Assays with Microfluidic Non-Contact Co-Culture

Fibroblasts have significant involvement in cancer progression and are an important therapeutic target for cancer. Here, we present a microfluidic non-contact co-culture device to analyze interactions between tumor cells and fibroblasts. Further, we investigate myofibroblast behaviors induced by lung tumor cells as responses to gallic acid and baicalein. Human lung fibroblast (HLF) and lung cancer cell line (A549) cells were introduced into neighboring, separated regions by well-controlled laminar flows. The phenotypic behavior and secretion activity of the tumor cells indicate that fibroblasts could become activated through paracrine signaling to create a supportive microenvironment for cancer cells when HLF is co-cultured with A549. Furthermore, both gallic acid (GA) and baicalein (BAE) could inhibit the activation of fibroblasts. In situ analysis of various cell communications via the paracrine pathway could be realizable in this contactless co-culture single device. This device facilitates a better understanding of interactions between heterotypic cells, thus exploring the mechanism of cancer, and performs anti-invasion drug assays in a relatively complex microenvironment.

CAF-derived HGF promotes cell proliferation and drug resistance by up-regulating the c-Met/PI3K/Akt and GRP78 signalling in ovarian cancer cells

The tumour microenvironment is a highly heterogeneous entity that plays crucial roles in cancer progression. As the most prominent stromal cell types, cancer-associated fibroblasts (CAFs) produce a variety of factors into the tumour microenvironment. In the present study, we firstly isolated CAFs from tumour tissues of the patients with ovarian cancer and demonstrated that the hepatocyte growth factor (HGF) was highly expressed in the supernatants of CAFs. CAF-derived HGF or human recombinant HGF promoted cell proliferation in human ovarian cell lines SKOV3 and HO-8910 cells. Western blotting analysis also showed that CAF-derived HGF or recombinant HGF activated c-Met/phosphoinositide 3-kinase (PI3K)/Akt and glucose-regulated protein 78 (GRP78) signalling pathways in ovarian cancer cells, and these effects could be abrogated by anti-HGF and c-Met inhibitor INCB28060. Moreover, HGF in CAF matrix attenuated paclitaxel (PAC)-caused inhibition of cell proliferation and increase in cell apoptosis through activating c-Met/PI3K/Akt and GRP78 pathways in SKOV3 and HO-8910 cells. The results in vitro were further validated in nude mice. These findings suggest that CAF-derived HGF plays crucial roles in cell proliferation and drug resistance in ovarian cancer cells.

A bladder cancer microenvironment simulation system based on a microfluidic co-culture model

A tumor microenvironment may promote tumor metastasis and progression through the dynamic interplay between neoplastic cells and stromal cells. In this work, the most representative and significant stromal cells, fibroblasts, endothelial cells, and macrophages were used as vital component elements and combined with bladder cancer cells to construct a bladder cancer microenvironment simulation system. This is the first report to explore bladder cancer microenvironments based on 4 types of cells co-cultured simultaneously. This simulation system comprises perfusion equipment, matrigel channel units, a medium channel and four indirect contact culture chambers, allowing four types of cells to simultaneously interact through soluble biological factors and metabolites. With this system, bladder cancer cells (T24) with a tendency to form a ‘reticular’ structure under 3 dimensional culture conditions were observed in real time. The microenvironment characteristics of paracrine interactions and cell motility were successfully simulated in this system. The phenotype change process in stromal cells was successfully reproduced in this system by testing the macrophage effector molecule Arg-1. Arg-1 was highly expressed in the simulated tumor microenvironment group. To develop “precision medicine” in bladder cancer therapy, bladder cancer cells were treated with different clinical ‘neo-adjuvant’ chemotherapy schemes in this system, and their sensitivity differences were fully reflected. This work provides a preliminary foundation for neo-adjuvant chemotherapy in bladder cancer, a theoretical foundation for tumor microenvironment simulation and promotes individual therapy in bladder cancer patients.

Organ-Tumor-on-a-Chip for Chemosensitivity Assay: A Critical Review

With a mortality rate over 580,000 per year, cancer is still one of the leading causes of death worldwide. However, the emerging field of microfluidics can potentially shed light on this puzzling disease. Unique characteristics of microfluidic chips (also known as micro-total analysis system) make them excellent candidates for biological applications. The ex vivo approach of tumor-on-a-chip is becoming an indispensable part of personalized medicine and can replace in vivo animal testing as well as conventional in vitro methods. In tumor-on-a-chip, the complex three-dimensional (3D) nature of malignant tumor is co-cultured on a microfluidic chip and high throughput screening tools to evaluate the efficacy of anticancer drugs are integrated on the same chip. In this article, we critically review the cutting edge advances in this field and mainly categorize each tumor-on-a-chip work based on its primary organ. Specifically, design, fabrication and characterization of tumor microenvironment; cell culture technique; transferring mechanism of cultured cells into the microchip; concentration gradient generators for drug delivery; in vitro screening assays of drug efficacy; and pros and cons of each microfluidic platform used in the recent literature will be discussed separately for the tumor of following organs: (1) Lung; (2) Bone marrow; (3) Brain; (4) Breast; (5) Urinary system (kidney, bladder and prostate); (6) Intestine; and (7) Liver. By comparing these microchips, we intend to demonstrate the unique design considerations of each tumor-on-a-chip based on primary organ, e.g., how microfluidic platform of lung-tumor-on-a-chip may differ from liver-tumor-on-a-chip. In addition, the importance of heart–liver–intestine co-culture with microvasculature in tumor-on-a-chip devices for in vitro chemosensitivity assay will be discussed. Such system would be able to completely evaluate the absorption, distribution, metabolism, excretion and toxicity (ADMET) of anticancer drugs and more realistically recapitulate tumor in vivo-like microenvironment.

Fibroblasts Enhance Migration of Human Lung Cancer Cells in a Paper-Based Coculture System

A multilayered paper-based platform is used to investigate the interactions between human lung tumor cells and fibroblasts that are isolated from primary patient tumor samples.

Different roles of myofibroblasts in the tumorigenesis of nonsmall cell lung cancer

Myofibroblasts play a critical role in the cancer cell growth, invasion, and tumor-associated vascularization during the carcinogenesis of nonsmall cell lung cancer (NSCLC), whereas the underlying molecular bases are not completely understood. We isolated Lin-negative, Sca1-low, and CD49e-high myofibroblasts from the NSCLC tissues of the patients and modified the levels of either transforming growth factor β 1 (TGFβ1) or vascular endothelial growth factor A (VEGF-A) in these cells. We found that coculture with TGFβ1-overexpressing myofibroblasts significantly decreased the NSCLC cell growth in an MTT assay through proliferation suppression rather than modulation of cell apoptosis, while significantly increased the NSCLC cell invasiveness in either a transwell migration assay or a scratch wound healing migration assay. However, modulation of TGFβ1 levels in myofibroblasts did not significantly alter vessel formation in a human umbilical vein endothelial cells (HUVECs) transwell collagen gel assay. On the other hand, overexpression of VEGF-A in myofibroblasts significantly increased vessel formation in the HUVECs transwell collagen gel assay. Together, these data suggest that myofibroblasts may regulate cancer cell growth and invasion through TGFβ1 but modulate cancer-associated neovascularization through VEGF-A. Hence, targeting different signaling pathways in myofibroblasts may delicately control NSCLC growth and invasion.

Cancer Associated Fibroblast-Derived Hepatocyte Growth Factor Inhibits the Paclitaxel-Induced Apoptosis of Lung Cancer A549 Cells by Up-Regulating the PI3K/Akt and GRP78 Signaling on a Microfluidic Platform

Tumor stroma and growth factors provide a survival environment to tumor cells and can modulate their chemoresistance by dysregulating several signal pathways. In this study, we fabricated a three-dimensional (3D) microfluidic chip using polydimethylsiloxane (PDMS) to investigate the impact of hepatocyte growth factor (HGF) from cancer-associated fibroblasts (CAF) on the Met/PI3K/AKT activation, glucose regulatory protein (GRP78) expression and the paclitaxel-induced A549 cell apoptosis. With a concentration gradient generator, the assembled chip was able to reconstruct a tumor microenvironment in vitro. We found high levels of HGF in the supernatants of CAF and the CAF matrix from the supernatants of activated HFL1 fibroblasts or HGF enhanced the levels of Met, PI3K and AKT phosphorylation and GRP78 expression in A549 cells cultured in a 3D cell chamber, which was abrogated by anti-HGF. Inhibition of Met attenuated the CAF matrix-enhanced PI3K/AKT phosphorylation and GRP78 expression while inhibition of PI3K reduced GRP78 expression, but not Met phosphorylation in A549 cells. Inhibition of GRP78 failed to modulate the CAF matrix-enhanced Met/PI3K/AKT phosphorylation in A549 cells. Furthermore, inhibition of PI3K or GRP78 enhanced spontaneous and paclitaxel-induced A549 cell apoptosis. Moreover, treatment with the CAF matrix inhibited spontaneous and medium or high dose of paclitaxel-induced A549 cell apoptosis. Inhibition of PI3K or GRP78 attenuated the CAF matrix-mediated inhibition on paclitaxel-induced A549 cell apoptosis. Our data indicated that HGF in the CAF matrix activated the Met/PI3K/AKT and up-regulated GRP78 expression, promoting chemoresistance to paclitaxel-mediated apoptosis in A549 cells. Our findings suggest that the microfluidic system may represent an ideal platform for signaling research and drug screening.