The Tyrosine Kinase Inhibitor Imatinib Augments Extracellular Fluid Exchange and Reduces Average Collagen Fibril Diameter in Experimental Carcinoma

Role of extracellular matrix architecture and signaling in melanoma therapeutic resistance

The extracellular matrix (ECM) is critical for maintaining tissue homeostasis therefore its production, assembly and mechanical stiffness are highly regulated in normal tissues. However, in solid tumors, increased stiffness resulting from abnormal ECM structural changes is associated with disease progression, an increased risk of metastasis and poor survival. As a dynamic and key component of the tumor microenvironment, the ECM is becoming increasingly recognized as an important feature of tumors, as it has been shown to promote several hallmarks of cancer via biochemical and biomechanical signaling. In this regard, melanoma cells are highly sensitive to ECM composition, stiffness and fiber alignment because they interact directly with the ECM in the tumor microenvironment via cell surface receptors, secreted factors or enzymes. Importantly, seeing as the ECM is predominantly deposited and remodeled by myofibroblastic stromal fibroblasts, it is a key avenue facilitating their paracrine interactions with melanoma cells. This review gives an overview of melanoma and further describes the critical roles that ECM properties such as ECM remodeling, ECM-related proteins and stiffness play in cutaneous melanoma progression, tumor cell plasticity and therapeutic resistance. Finally, given the emerging importance of ECM dynamics in melanoma, future perspectives on therapeutic strategies to normalize the ECM in tumors are discussed.

Role of collagen regulators in cancer treatment: A comprehensive review

Abstract:

Collagen is the most important structural protein and also a main component of extra-cellular matrix (ECM). It plays a role in tumor progression. Collagen can be regulated by altering it’s biosynthesis pathway through various signaling pathways, receptors and genes. Activity of cancer cells can also be regulated by other ECM components like metalloproteinases, hyaluronic acid, fibronectin and so on. Hypoxia is also one of the condition which leads to cancer progression by stimulating the expression of procollagen lysine as a collagen crosslinker, which increases the size of collagen fibres promoting cancer spread. The collagen content in cancerous cells leads to resistance in chemotherapy. So, to reduce this resistance, some of the collagen regulating therapies are introduced, which include inhibiting its biosynthesis, disturbing cancer cell signaling pathway, mediating ECM components and directly utilizing collagenase. This study is an effort to compile the strategies reported to control the collagen level and different collagen inhibitors reported so far. More research is needed in this area, growing understandings of collagen’s structural features and its role in cancer progression will aid in the advancement of newer chemotherapies.

Tenomodulin and Chondromodulin-1 Are Both Required to Maintain Biomechanical Function and Prevent Intervertebral Disc Degeneration

OBJECTIVE

The underlying mechanisms and molecular factors influencing intervertebral disc (IVD) homeostasis and degeneration remain clinically relevant. Tenomodulin (Tnmd) and chondromodulin (Chm1) are antiangiogenic transmembrane glycoproteins, with cleavable C-terminus, expressed by IVD cells that are implicated in the onset of degenerative processes. We evaluate the organ-level biomechanical impact of knocking out Tnmd alone, and Tnmd and Chm1, simultaneously.

DESIGN

Caudal (c5-8) and lumbar vertebrae (L1-4) of skeletally mature male and female 9-month-old wildtype (WT), Tnmd knockout (Tnmd^-/-), and Tnmd/Chm1 double knockout (Tnmd^-/-/Chm^-/-) mice were used (n = 9-13 per group). Disc height index (DHI), histomorphological changes, and axial, torsional, creep, and failure biomechanical properties were evaluated. Differences were assessed by one-way ANOVA with post hoc Bonferroni-corrected comparisons (P < 0.05).

RESULTS

Tnmd^-/-/Chm1^-/- IVDs displayed increased DHI and histomorphological scores that indicated increased IVD degeneration compared to the WT and Tnmd^-/- groups. Double knockout IVDs required significantly less torque and energy to initiate torsional failure. Creep parameters were comparable between all groups, except for the slow time constant, which indicated faster outward fluid flow. Tnmd^-/- IVDs lost fluid faster than the WT group, and this effect was amplified in the double knockout IVDs.

CONCLUSION

Knocking out Tnmd and Chm1 affects IVD fluid flow and organ-level biomechanical function and therefore may play a role in contributing to IVD degeneration. Larger effects of the Tnmd and Chm1 double knockout mice compared to the Tnmd single mutant suggest that Chm1 may play a compensatory role in the Tnmd single mutant IVDs.

Cancer-Associated Fibroblasts and Tumor-Associated Macrophages in Cancer and Cancer Immunotherapy

Our understanding of the tumor microenvironment (TME), including the interplay between tumor cells, stromal cells, immune cells, and extracellular matrix components, is mandatory for the innovation of new therapeutic approaches in cancer. The cell-cell communication within the TME plays a pivotal role in the evolution and progression of cancer. Cancer-associated fibroblasts (CAF) and tumor-associated macrophages (TAM) are major cell populations in the stroma of all solid tumors and often exert protumorigenic functions; however, the origin and precise functions of CAF and TAM are still incompletely understood. CAF and TAM hold significant potential as therapeutic targets to improve outcomes in oncology when combined with existing therapies. The regulation of CAF/TAM communication and/or their differentiation could be of high impact for improving the future targeted treatment strategies. Nevertheless, there is much scope for research and innovation in this field with regards to the development of novel drugs. In this review, we elaborate on the current knowledge on CAF and TAM in cancer and cancer immunotherapy. Additionally, by focusing on their heterogenous functions in different stages and types of cancer, we explore their role as potential therapeutic targets and highlight certain aspects of their functions that need further research.

The extracellular matrix: A key player in the pathogenesis of hematologic malignancies

Hematopoietic stem and progenitor cells located in the bone marrow lay the foundation for multiple lineages of mature hematologic cells. Bone marrow niches are architecturally complex with specific cellular, physiochemical, and biomechanical factors. Increasing evidence suggests that the bone marrow microenvironment contributes to the pathogenesis of hematological neoplasms. Numerous studies have deciphered the role of genetic mutations and chromosomal translocations in the development hematologic malignancies. Significant progress has also been made in understanding how the cellular components and cytokine interactions within the bone marrow microenvironment promote the evolution of hematologic cancers. Although the extracellular matrix is known to be a key player in the pathogenesis of various diseases, it's role in the progression of hematologic malignancies is less understood. In this review, we discuss the interactions between the extracellular matrix and malignant cells, and provide an overview of the role of extracellular matrix remodeling in sustaining hematologic malignancies.

Advancing Aptamers as Molecular Probes for Cancer Theranostic Applications-The Role of Molecular Dynamics Simulation

Theranostics cover emerging technologies for cell biomarking for disease diagnosis and targeted introduction of drug ingredients to specific malignant sites. Theranostics development has become a significant biomedical research endeavor for effective diagnosis and treatment of diseases, especially cancer. An efficient biomarking and targeted delivery strategy for theranostic applications requires effective molecular coupling of binding ligands with high affinities to specific receptors on the cancer cell surface. Bioaffinity offers a unique mechanism to bind specific target and receptor molecules from a range of non-targets. The binding efficacy depends on the specificity of the affinity ligand toward the target molecule even at low concentrations. Aptamers are fragments of genetic materials, peptides, or oligonucleotides which possess enhanced specificity in targeting desired cell surface receptor molecules. Aptamer-target binding results from several inter-molecular interactions including hydrogen bond formation, aromatic stacking of flat moieties, hydrophobic interaction, electrostatic, and van der Waals interactions. Advancements in Systematic Evolution of Ligands by Exponential Enrichment (SELEX) assay has created the opportunity to artificially generate aptamers that specifically bind to desired cancer and tumor surface receptors with high affinities. This article discusses the potential application of molecular dynamics (MD) simulation to advance aptamer-mediated receptor targeting in targeted cancer therapy. MD simulation offers real-time analysis of the molecular drivers of the aptamer-receptor binding and generate optimal receptor binding conditions for theranostic applications. The article also provides an overview of different cancer types with focus on receptor biomarking and targeted treatment approaches, conventional molecular probes, and aptamers that have been explored for cancer cells targeting.

The role of collagen in cancer: from bench to bedside

Collagen is the major component of the tumor microenvironment and participates in cancer fibrosis. Collagen biosynthesis can be regulated by cancer cells through mutated genes, transcription factors, signaling pathways and receptors; furthermore, collagen can influence tumor cell behavior through integrins, discoidin domain receptors, tyrosine kinase receptors, and some signaling pathways. Exosomes and microRNAs are closely associated with collagen in cancer. Hypoxia, which is common in collagen-rich conditions, intensifies cancer progression, and other substances in the extracellular matrix, such as fibronectin, hyaluronic acid, laminin, and matrix metalloproteinases, interact with collagen to influence cancer cell activity. Macrophages, lymphocytes, and fibroblasts play a role with collagen in cancer immunity and progression. Microscopic changes in collagen content within cancer cells and matrix cells and in other molecules ultimately contribute to the mutual feedback loop that influences prognosis, recurrence, and resistance in cancer. Nanoparticles, nanoplatforms, and nanoenzymes exhibit the expected gratifying properties. The pathophysiological functions of collagen in diverse cancers illustrate the dual roles of collagen and provide promising therapeutic options that can be readily translated from bench to bedside. The emerging understanding of the structural properties and functions of collagen in cancer will guide the development of new strategies for anticancer therapy.

Effect of drug-loaded microbubbles combined with ultrasound on the apoptosis of cancer cells and the expression of Bax and Bcl-2 in a rabbit VX2 liver tumor model

The aim of the present study was to investigate whether the use of drug-loaded microbubbles combined with ultrasound promotes the apoptosis of cancer cells by regulating B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax) expression. Adriamycin-loaded PLGA nanoparticles (ADM-NP) were fabricated using a modified emulsification process. Lipid microbubbles (NH₂-MB) were prepared by mechanical vibration. The carboxyl groups of ADM-NP and NH₂-MB underwent a condensation reaction after 48 h, and adriamycin-loaded PLGA nanoparticles microbubble complexes (ADM-NMC) were obtained. High-performance liquid chromatography demonstrated that the entrapment efficiency and drug loading of ADM-NMC were 85.32 ± 5.41% and 7.91 ± 0.27%, respectively. The VX2 liver cancer model was established in 30 New Zealand rabbits, which were subsequently divided into three groups (n=10): a control group that received 5 ml of saline, an ADM-NP group that received 5 ml of ADM-NP and an ADM-NMC group that received 5 ml of ADM-NMC. Rabbits in the ADM-NP and ADM-NMC groups underwent irradiation 120 s with low frequency ultrasound (1 MHz, 0.5 W/cm²) for 120 s following injection. The echogenicity of tumors markedly increased following ADM-NP and ADM-NMC treatment. Staining with hematoxylin and eosin demonstrated that the tumor shape became more normal in the ADM-NP and ADM-NMC groups compared with the control group. Immunohistochemical staining and Western blotting determined that the expression of Bax increased and the expression of Bcl-2 decreased following treatment with ADM-NP and ADM-NMC. Cancer cell apoptosis was detected by flow cytometry and it was determined that apoptosis significantly increased following treatment with ADM-NP and ADM-NMC (P<0.01). Therefore, the present study demonstrated that the use of drug-loaded microbubbles combined with ultrasound may enhance the efficiency of tumor inhibition. This may be due to the promotion of cancer cell apoptosis via regulation of Bax and Bcl-2 expression.

The endoplasmic reticulum-resident collagen chaperone Hsp47 interacts with and promotes the secretion of decorin, fibromodulin, and lumican

The build-up of diversified and tissue-specific assemblies of extracellular matrix (ECM) proteins depends on secreted and cell surface-located molecular arrays that coordinate ECM proteins into discrete designs. The family of small leucine-rich proteins (SLRPs) associates with and dictates the structure of fibrillar collagens, which form the backbone of most ECM types. However, whether SLRPs form complexes with proteins other than collagens is unclear. Here, we demonstrate that heat shock protein 47 (Hsp47), a well-established endoplasmic reticulum-resident collagen chaperone, also binds the SLRPs decorin, lumican, and fibromodulin with affinities comparable with that in the Hsp47-type I collagen interaction. Furthermore, we show that a lack of Hsp47 inhibits the cellular secretion of decorin and lumican. Our results expand the understanding of the concerted molecular interactions that control the secretion and organization of a functional collagenous ECM.

Inhibition of integrin αVβ6 changes fibril thickness of stromal collagen in experimental carcinomas

Background

Chemotherapeutic efficacy can be improved by targeting the structure and function of the extracellular matrix (ECM) in the carcinomal stroma. This can be accomplished by e.g. inhibiting TGF-β1 and -β3 or treating with Imatinib, which results in scarcer collagen fibril structure in xenografted human KAT-4/HT29 (KAT-4) colon adenocarcinoma.

Methods

The potential role of α_Vβ₆ integrin-mediated activation of latent TGF-β was studied in cultured KAT-4 and Capan-2 human ductal pancreatic carcinoma cells as well as in xenograft carcinoma generated by these cells. The monoclonal α_Vβ₆ integrin-specific monoclonal antibody 3G9 was used to inhibit the α_Vβ₆ integrin activity.

Results

Both KAT-4 and Capan-2 cells expressed the α_Vβ₆ integrin but only KAT-4 cells could utilize this integrin to activate latent TGF-β in vitro. Only when Capan-2 cells were co-cultured with human F99 fibroblasts was the integrin activation mechanism triggered, suggesting a more complex, fibroblast-dependent, activation pathway. In nude mice, a 10-day treatment with 3G9 reduced collagen fibril thickness and interstitial fluid pressure in KAT-4 but not in the more desmoplastic Capan-2 tumors that, to achieve a similar effect, required a prolonged 3G9 treatment. In contrast, a 10-day direct inhibition of TGF-β1 and -β3 reduced collagen fibril thickness in both tumor models.

Conclusion

Our data demonstrate that the α_Vβ₆-directed activation of latent TGF-β plays a pivotal role in modulating the stromal collagen network in carcinoma, but that the sensitivity to α_Vβ₆ inhibition depends on the simultaneous presence of alternative paths for latent TGF-β activation and the extent of desmoplasia.

Electronic supplementary material

The online version of this article (10.1186/s12964-018-0249-7) contains supplementary material, which is available to authorized users.

Tumour tissue transport after intraperitoneal anticancer drug delivery

Intraperitoneal (IP) drug delivery, either as an intraoperative chemoperfusion or as an adjuvant, repeated instillation, is an established treatment modality in patients with peritoneal carcinomatosis. The efficacy of IP drugs depends on its ability to penetrate the tumour stroma in order to reach their (sub)cellular target. It is known, that drug penetration after IP delivery is limited to a few millimetres. Here, we review the basic tissue transport mechanisms after IP delivery and discuss the biophysical barriers and obstacles that limit penetration distance. In addition, we review the physical and pharmaceutical interventions that have been studied in order to improve delivery of small molecular and macromolecular drugs after IP instillation. These interventions could inform the design of future clinical trials aiming at an improved efficacy of IP-based drug delivery in carcinomatosis patients.

Asporin-deficient mice have tougher skin and altered skin glycosaminoglycan content and structure

The main structural component of connective tissues is fibrillar, cross-linked collagen whose fibrillogenesis can be modulated by Small Leucine-Rich Proteins/Proteoglycans (SLRPs). Not all SLRPs’ effects on collagen and extracellular matrix in vivo have been elucidated; one of the less investigated SLRPs is asporin. Here we describe the successful generation of an Aspn^-/- mouse model and the investigation of the Aspn^-/- skin phenotype. Functionally, Aspn^-/- mice had an increased skin mechanical toughness, although there were no structural changes present on histology or immunohistochemistry. Electron microscopy analyses showed 7% thinner collagen fibrils in Aspn^-/- mice (not statistically significant). Several matrix genes were upregulated, including collagens (Col1a1, Col1a2, Col3a1), matrix metalloproteinases (Mmp2, Mmp3) and lysyl oxidases (Lox, Loxl2), while lysyl hydroxylase (Plod2) was downregulated. Intriguingly no differences were observed in collagen protein content or in collagen cross-linking-related lysine oxidation or hydroxylation. The glycosaminoglycan content and structure in Aspn^-/- skin was profoundly altered: chondroitin/dermatan sulfate was more than doubled and had an altered composition, while heparan sulfate was halved and had a decreased sulfation. Also, decorin and biglycan were doubled in Aspn^-/- skin. Overall, asporin deficiency changes skin glycosaminoglycan composition, and decorin and biglycan content, which may explain the changes in skin mechanical properties.

Fibromodulin deficiency reduces collagen structural network but not glycosaminoglycan content in a syngeneic model of colon carcinoma

Tumor barrier function in carcinoma represents a major challenge to treatment and is therefore an attractive target for increasing drug delivery. Variables related to tumor barrier include aberrant blood vessels, high interstitial fluid pressure, and the composition and structure of the extracellular matrix. One of the proteins associated with dense extracellular matrices is fibromodulin, a collagen fibrillogenesis modulator expressed in tumor stroma but scarce in normal loose connective tissues. Here, we investigated the effects of fibromodulin on stroma ECM in a syngeneic murine colon carcinoma model. We show that fibromodulin deficiency decreased collagen fibril thickness but glycosaminoglycan content and composition were unchanged. Furthermore, vascular density, pericyte coverage and macrophage amount were unaffected. Fibromodulin can therefore be a unique effector of dense collagen matrix assembly in tumor stroma and, without affecting other major matrix components or the cellular composition, can function as a main agent in tumor barrier function.

Imatinib increases oxygen delivery in extracellular matrix-rich but not in matrix-poor experimental carcinoma

BACKGROUND

Imatinib causes increased turnover of stromal collagen, reduces collagen fibril diameter, enhances extracellular fluid turnover and lowers interstitial fluid pressure (IFP) in the human colonic carcinoma KAT-4/HT-29 (KAT-4) xenograft model.

METHODS

We compared the effects of imatinib on oxygen levels, vascular morphology and IFP in three experimental tumor models differing in their content of a collagenous extracellular matrix.

RESULTS

Neither the KAT4 and CT-26 colonic carcinoma models, nor B16BB melanoma expressed PDGF β-receptors in the malignant cells. KAT-4 tumors exhibited a well-developed ECM in contrast to the other two model systems. The collagen content was substantially higher in KAT-4 than in CT-26, while collagen was not detectable in B16BB tumors. The pO₂ was on average 5.4, 13.9 and 19.3 mmHg in KAT-4, CT-26 and B16BB tumors, respectively. Treatment with imatinib resulted in similar pO₂-levels in all three tumor models but only in KAT-4 tumors did the increase reach statistical significance. It is likely that after imatinib treatment the increase in pO₂ in KAT-4 tumors is caused by increased blood flow due to reduced vascular resistance. This notion is supported by the significant reduction observed in IFP in KAT-4 tumors after imatinib treatment. Vessel area varied between 4.5 and 7% in the three tumor models and was not affected by imatinib treatment. Imatinib had no effect on the fraction of proliferating cells, whereas the fraction of apoptotic cells increased to a similar degree in all three tumor models.

CONCLUSION

Our data suggest that the effects of imatinib on pO₂-levels depend on a well-developed ECM and provide further support to the suggestion that imatinib acts by causing interstitial stroma cells to produce a less dense ECM, which would in turn allow for an increased blood flow. The potential of imatinib treatment to render solid tumors more accessible to conventional treatments would therefore depend on the degree of tumor desmoplasia.