Cell migration towards CXCL12 in leukemic cells compared to breast cancer cells

The role of PKC and PKD in CXCL12 and CXCL13 directed malignant melanoma and acute monocytic leukemic cancer cell migration

Cancer metastasis is the leading cause of cancer related mortality. Chemokine receptors and proteins in their downstream signalling axis represent desirable therapeutic targets for the prevention of metastasis. Despite this, current therapeutics have experienced limited success in clinical trials due to a lack of insight into the downstream signalling pathway of specific chemokine receptor cascades in different tumours. In this study, we investigated the role of protein kinase C (PKC) and protein kinase D (PKD) in CXCL12 and CXCL13 stimulated SK-MEL-28 (malignant melanoma) and THP-1 (acute monocytic leukaemia) cell migration. While PKC and PKD had no active role in CXCL12 or CXCL13 stimulated THP-1 cell migration, PKC and PKD inhibition reduced CXCL12 stimulated migration and caused profound effects upon the cytoskeleton of SK-MEL-28 cells. Furthermore, only PKC and not PKD inhibition reduced CXCL13 stimulated migration in SK-MEL-28 cells however PKC inhibition failed to stimulate any changes to the actin cytoskeleton. These findings indicate that PKC inhibitors would be a useful therapeutic for the prevention of both CXCL12 and CXCL13 stimulated migration and PKD inhibitors for CXCL12 stimulated migration in malignant melanoma.

Tibouchina granulosa Leaves Present Anti-Inflammatory Effect

The ethanol extract (EE) prepared from the leaves of Tibouchina granulosa, and its fraction in ethyl acetate (fEA) were evaluated concerning their capacity to reduce inflammation in different experimental models. fEA was also studied concerning its chemical constituents. EE and fEA were assayed for their anti-inflammatory potential, using formalin-induced licking behavior and carrageenan-induced inflammation into the subcutaneous air pouch (SAP) models. Reduction in polymorphonuclear cells (PMN) activation was performed in freshly isolated PMN. Chromatographic analysis of fEA was performed by HPLC-DAD. Hispiduloside was isolated as the main constituent in fEA, and its quantity was estimated to be 39.3% in fEA. EE (30 mg/kg) significantly reduced the second phase of formalin-induced licking. fEA demonstrated a reduction in leukocyte migration into the SAP. EE and fEA drastically reduced cytokines (TNF-α, IL-1β, and IFN-γ), nitric oxide (NO) production, in vitro PMN migration induced by C5a and IL-8, and TNF-α and IL-1β gene expression. Taken together, our data indicate that either ethanol extract or its fEA fraction from leaves of T. granulosa present an anti-inflammatory effect, contributing to the pharmacological and chemical knowledge of this species and confirming the rationale behind its traditional use.

Cell Trafficking at the Intersection of the Tumor-Immune Compartments

Migration is an essential cellular process that regulates human organ development and homeostasis as well as disease initiation and progression. In cancer, immune and tumor cell migration is strongly associated with immune cell infiltration, immune escape, and tumor cell metastasis, which ultimately account for more than 90% of cancer deaths. The biophysics and molecular regulation of the migration of cancer and immune cells have been extensively studied separately. However, accumulating evidence indicates that, in the tumor microenvironment, the motilities of immune and cancer cells are highly interdependent via secreted factors such as cytokines and chemokines. Tumor and immune cells constantly express these soluble factors, which produce a tightly intertwined regulatory network for these cells' respective migration. A mechanistic understanding of the reciprocal regulation of soluble factor-mediated cell migration can provide critical information for the development of new biomarkers of tumor progression and of tumor response to immuno-oncological treatments. We review the biophysical andbiomolecular basis for the migration of immune and tumor cells and their associated reciprocal regulatory network. We also describe ongoing attempts to translate this knowledge into the clinic.

The CXCL12/CXCR4/ACKR3 Axis in the Tumor Microenvironment: Signaling, Crosstalk, and Therapeutic Targeting

Elevated expression of the chemokine receptors CXCR4 and ACKR3 and of their cognate ligand CXCL12 is detected in a wide range of tumors and the tumor microenvironment (TME). Yet, the molecular mechanisms by which the CXCL12/CXCR4/ACKR3 axis contributes to the pathogenesis are complex and not fully understood. To dissect the role of this axis in cancer, we discuss its ability to impinge on canonical and less conventional signaling networks in different cancer cell types; its bidirectional crosstalk, notably with receptor tyrosine kinase (RTK) and other factors present in the TME; and the infiltration of immune cells that supporttumor progression. We discuss current and emerging avenues that target the CXCL12/CXCR4/ACKR3 axis. Coordinately targeting both RTKs and CXCR4/ACKR3 and/or CXCL12 is an attractive approach to consider in multitargeted cancer therapies. In addition, inhibiting infiltrating immune cells or reactivating the immune system along with modulating the CXCL12/CXCR4/ACKR3 axis in the TME has therapeutic promise.

The role of PKC in CXCL8 and CXCL10 directed prostate, breast and leukemic cancer cell migration

Migration of tumour cells is a fundamental process for the formation and progression of metastasis in malignant diseases. Chemokines binding to their cognate receptors induce the migration of cancer cells, however, the molecular signalling pathways involved in this process are not fully understood. Protein kinase C (PKC) has been shown to regulate cell migration, adhesion and proliferation. In order to identify a connection between PKC and tumour progression in breast, prostate and leukaemia cells, the effect of PKC on CXCL8 or CXCL10-mediated cell migration and morphology was analysed. We tested the speed of the migrating cells, morphology, and chemotaxis incubated with different PKC isoforms inhibitors- GF109203X, staurosporine and PKCζ pseudosubstrate inhibitor (PKCζi). We found that the migration of CXCL8-driven PC3 and MDA-MB231 cells in the presence of conventional, novel or atypical PKCs was not affected, but atypical PKCζ is crucial for THP-1 chemotaxis. The speed of CXCL10-activated PC3 and MDA-MB231 cells was significantly reduced in the presence of conventional, novel and atypical PKCζ. THP-1 chemotaxis was again affected by atypical PKCζi. On the other hand, cell area, circularity or aspect ratio were affected by staurosporine in CXCL8 or CXCL10-activated cells, demonstrating a role of PKCα in the rearrangement of the cytoskeleton regardless of the effect on the migration. Consequently, this allows the speculation that different PKC isoforms induce different outcomes in migration and actin cytoskeleton based on the chemokine receptor and/or the cell type.

The CXCL12-CXCR4/CXCR7 axis as a mechanism of immune resistance in gastrointestinal malignancies

Single agent checkpoint inhibitor therapy has not been effective for most gastrointestinal solid tumors, but combination therapy with drugs targeting additional immunosuppressive pathways is being attempted. One such pathway, the CXCL12-CXCR4/CXCR7 chemokine axis, has attracted attention due to its effects on tumor cell survival and metastasis as well as immune cell migration. CXCL12 is a small protein that functions in normal hematopoietic stem cell homing in addition to repair of damaged tissue. Binding of CXCL12 to CXCR4 leads to activation of G protein signaling kinases such as P13K/mTOR and MEK/ERK while binding to CXCR7 leads to β-arrestin mediated signaling. While some gastric and colorectal carcinoma cells have been shown to make CXCL12, the primary source in pancreatic cancer and peritoneal metastases is cancer-associated fibroblasts. Binding of CXCL12 to CXCR4 and CXCR7 on tumor cells leads to anti-apoptotic signaling through Bcl-2 and survivin upregulation, as well as promotion of the epithelial-to-mesechymal transition through the Rho-ROCK pathway and alterations in cell adhesion molecules. High levels of CXCL12 seen in the bone marrow, liver, and spleen could partially explain why these are popular sites of metastases for many tumors. CXCL12 is a chemoattractant for lymphocytes at lower levels, but becomes chemorepellant at higher levels; it is unclear exactly what gradient exists in the tumor microenvironment and how this influences tumor-infiltrating lymphocytes. AMD3100 (Plerixafor or Mozobil) is a small molecule CXCR4 antagonist and is the most frequently used drug targeting the CXCL12-CXCR4/CXCR7 axis in clinical trials for gastrointestinal solid tumors currently. Other small molecules and monoclonal antibodies against CXCR4 are being trialed. Further understanding of the CXCL12- CXCR4/CXCR7 chemokine axis in the tumor microenvironment will allow more effective targeting of this pathway in combination immunotherapy.

CXCL12-CXCL4 heterodimerization prevents CXCL12-driven breast cancer cell migration

Despite improvements in cancer early detection and treatment, metastatic breast cancer remains deadly. Current therapeutic approaches have very limited efficacy in patients with triple negative breast cancer. Among the many mechanisms associated that contribute to cancer progression, signaling through the CXCL12-CXCR4 is an essential step in cancer cell migration. We previously demonstrated the formation of CXCL12-CXCL4 heterodimers (Carlson et al., 2013). Here, we investigated whether CXCL12-CXCL4 heterodimers alter tumor cell migration. CXCL12 alone dose-dependently promoted the MDA-MB 231 cell migration (p < .05), which could be prevented by blocking the CXCR4 receptor. The addition of CXCL4 inhibited the CXCL12-induced cell migration (p < .05). Using NMR spectroscopy, we identified the CXCL4-CXCL12 binding interface. Moreover, we generated a CXCL4-derived peptide homolog of the binding interface that mimicked the activity of native CXCL4 protein. These results confirm the formation of CXCL12-CXCL4 heterodimers and their inhibitory effects on the migration of breast tumors cells. These findings suggest that specific peptides mimicking heterodimerization of CXCL12 might prevent breast cancer cell migration.

Hyperbaric oxygen improves functional recovery of rats after spinal cord injury via activating stromal cell-derived factor-1/CXC chemokine receptor 4 axis and promoting brain-derived neurothrophic factor expression

Background:

Spinal cord injury (SCI) is a worldwide medical concern. This study aimed to elucidate the mechanism underlying the protective effect of hyperbaric oxygen (HBO) against SCI-induced neurologic defects in rats via exploring the stromal cell-derived factor-1 (SDF-1)/CXC chemokine receptor 4 (CXCR4) axis and expression of brain-derived neurotrophic factor (BDNF).

Methods:

An acute SCI rat model was established in Sprague-Dawley rats using the Allen method. Sixty rats were divided into four groups (n = 15 in each group): sham-operated, SCI, SCI treated with HBO (SCI + HBO), and SCI treated with both HBO and AMD3100 (an antagonist of CXCR4; SCI + HBO + AMD) groups. The rats were treated with HBO twice a day for 3 days and thereafter once a day after the surgery for up to 28 days. Following the surgery, neurologic assessments were performed with the Basso-Bettie-Bresnahan (BBB) scoring system on postoperative day (POD) 7, 14, 21, and 28. Spinal cord tissues were harvested to assess the expression of SDF-1, CXCR4, and BDNF at mRNA and protein levels, using quantitative real-time polymerase chain reaction, Western blot analysis, and histopathologic analysis.

Results:

HBO treatment recovered SCI-induced descent of BBB scores on POD 14, (1.25 ± 0.75 vs. 1.03 ± 0.66, P < 0.05), 21 (5.27 ± 0.89 vs. 2.56 ± 1.24, P < 0.05), and 28 (11.35 ± 0.56 vs. 4.23 ± 1.20, P < 0.05) compared with the SCI group. Significant differences were found in the mRNA levels of SDF-1 (mRNA: day 21, SCI + HBO vs. SCI + HBO + AMD, 2.89 ± 1.60 vs. 1.56 ± 0.98, P < 0.05), CXCR4 (mRNA: day 7, SCI + HBO vs. SCI, 2.99 ± 1.60 vs.1.31 ± 0.98, P < 0.05; day 14, SCI + HBO vs. SCI + HBO + AMD, 4.18 ± 1.60 vs. 0.80 ± 0.34, P < 0.05; day 21, SCI + HBO vs. SCI, 2.10 ± 1.01 vs.1.15 ± 0.03, P < 0.05), and BDNF (mRNA: day 7, SCI + HBO vs. SCI, 3.04 ± 0.41 vs. 2.75 ± 0.31, P < 0.05; day 14, SCI + HBO vs. SCI, 3.88 ± 1.59 vs. 1.11 ± 0.40, P < 0.05), indicating the involvement of SDF-1/CXCR4 axis in the protective effect of HBO.

Conclusions:

HBO might promote the recovery of neurologic function after SCI in rats via activating the SDF-1/CXCR4 axis and promoting BDNF expression.

3D models of the bone marrow in health and disease: yesterday, today and tomorrow

The complex interaction between hematopoietic stem cells (HSCs) and their microenvironment in the human bone marrow ensures a life-long blood production by balancing stem cell maintenance and differentiation. This so-called HSC niche can be disturbed by malignant diseases. Investigating their consequences on hematopoiesis requires deep understanding of how the niches function in health and disease. To facilitate this, biomimetic models of the bone marrow are needed to analyse HSC maintenance and hematopoiesis under steady-state and diseased conditions. Here, 3D bone marrow models, their fabrication methods (including 3D bioprinting) and implementations recapturing bone marrow functions in health and diseases, are presented.

Migration Assay for Leukemic Cells in a 3D Matrix Toward a Chemoattractant

In leukemia, leukemic cells hijack the hematopoietic stem cell (HSC) microenvironment in the bone marrow-the so-called stem cell niche-by flooding the niche with clonal progeny of leukemic cells. They can exploit signaling pathways which are critical for HSC development to support their own survival, homing, and maintenance. These interactions of leukemic cells with the microenvironment have an impact on therapy progress and patient outcome. Therefore, signals for homing and anchorage of leukemic cells to the bone marrow have to be investigated by using tools that allow the migration of cells toward critical signals. Here, we describe an in vitro migration assay for leukemic cells toward a chemoattractant in a 3D environment exemplified by migration of the cell line OCI-AML3 to a CXC motif chemokine ligand 12 (CXCL12) gradient. For this purpose, a chemotaxis slide is filled with a hydrogel system mimicking the extracellular matrix in vivo. The cells are encapsulated into the hydrogel network during polymerization, and a CXCL12 gradient is introduced in the enclosed chambers to trigger migration. Cell migration in the 3D network of the hydrogel is monitored by time-lapse microscopy. We describe the experimental setup and the tools for cell tracking and data analysis.

Nitric oxide functions in stromal cell-derived factor-1-induced cytoskeleton changes and the migration of Jurkat cells

Stromal cell-derived factor-1 (SDF-1) regulates multiple cell signal pathways in a variety of cellular functions, including cell migration, proliferation, survival and angiogenesis. SDF-1-induced chemotaxis is an important step of lymphocyte migration. However, the molecular mechanisms that modulate SDF-1-mediated lymphocyte migration are not well identified. Nitric oxide (NO) has been found to function as a signaling molecule in a number of signaling pathways, including migration. In the present study, the potential role of NO in SDF-1-induced migration and the association between NO and the cytoskeletal changes of Jurkat cells was investigated. The present study demonstrated that Jurkat cells induced the production of NO by SDF-1 stimulation, using Griess reaction method and western blot analysis, and that NO was involved in SDF-1-induced rearrangement and polymerization of the cytoskeleton, using NOS inhibitor L-NMMA. Furthermore, NO was required for the migration of Jurkat cells. The research suggested that NO signaling pathways exerted a critical role in SDF-1-induced cytoskeleton changes and the migration of Jurkat cells. This work provides insight into the migration mechanism of acute lymphoblastic leukemia and provides an effective theoretical basis for therapy strategies for acute lymphoblastic leukemia.

CXCR4 and its ligand CXCL12 display opposite expression profiles in feline mammary metastatic disease, with the exception of HER2-overexpressing tumors

BACKGROUND

The receptor CXCR4 and its ligand CXCL12 play crucial roles in breast cancer. Despite the fact that the spontaneous feline mammary carcinoma (FMC) is considered a suitable model for breast cancer studies, the importance of the CXCR4/CXCL12 axis in FMC is completely unknown. Therefore, this work aims to elucidate the role of CXCR4 and its ligand in the progression of FMC and metastatic disease.

METHODS

CXCR4 and CXCL12 expression was analyzed by immunohistochemistry and immunofluorescence on primary tumors (PT), regional and distant metastases of female cats with mammary carcinoma and correlated with serum CXCL12 levels, tumor molecular subtypes and clinicopathological features.

RESULTS

CXCR4 was more expressed in PT than in metastases (p = 0.0067), whereas CXCL12 was highly expressed in metastatic lesions located in liver and lung (p < 0.0001), as reported for human breast cancer. Moreover, cats with CXCR4 positive PT exhibited significantly lower serum CXCL12 levels than cats with CXCR4 negative mammary carcinomas (p = 0.0324). At metastatic lesions, HER2-overexpressing tumors presented higher CXCR4 expression than the other molecular tumor subtypes (p = 0.012) and significant differences in overall (p = 0.0147) and disease-free survival (p = 0.0279) curves between the cats with CXCL12 positive and CXCL12 negative tumors were found. Indeed, CXCL12 negative PT were associated with unfavorable prognosis in cats with HER2-overexpressing tumors.

CONCLUSIONS

This work exposes part of the complex interaction between CXCR4 and CXCL12 in PT, but also in metastases of a breast cancer model. These findings could uncover novel therapeutic tools to be used in cats and humans.

SDF-1/CXCR4 axis induces human dental pulp stem cell migration through FAK/PI3K/Akt and GSK3β/β-catenin pathways

SDF-1 (stromal cell derived factor-1) has been found to be widely expressed during dental pulp inflammation, while hDPSCs (human dental pulp stem cells) contribute to the repair of dental pulp. We showed that the migration of hDPSCs was induced by SDF-1 in a concentration-dependent manner and could be inhibited with siCXCR4 (C-X-C chemokine receptor type 4) and siCDC42 (cell division control protein 42), as well as drug inhibitors such as AMD3100 (antagonist of CXCR4), LY294002 (inhibitor of PI3K) and PF573228 (inhibitor of FAK). It was also confirmed that SDF-1 regulated the phosphorylation of FAK (focal adhesion kinases) on cell membranes and the translocation of β-catenin into the cell nucleus. Subsequent experiments confirmed that the expression of CXCR4 and β-catenin and the phosphorylation of FAK, PI3K (phosphoinositide 3-kinase), Akt and GSK3β (glycogen synthase kinase-3β) were altered significantly with SDF-1 stimulation. FAK and PI3K worked in coordination during this process. Our findings provide direct evidence that SDF-1/CXCR4 axis induces hDPSCs migration through FAK/PI3K/Akt and GSK3β/β-catenin pathways, implicating a novel mechanism of dental pulp repair and a possible application of SDF-1 for the treatment of pulpitis.

Cytokine Regulation of Metastasis and Tumorigenicity

The human body combats infection and promotes wound healing through the remarkable process of inflammation. Inflammation is characterized by the recruitment of stromal cell activity including recruitment of immune cells and induction of angiogenesis. These cellular processes are regulated by a class of soluble molecules called cytokines. Based on function, cell target, and structure, cytokines are subdivided into several classes including: interleukins, chemokines, and lymphokines. While cytokines regulate normal physiological processes, chronic deregulation of cytokine expression and activity contributes to cancer in many ways. Gene polymorphisms of all types of cytokines are associated with risk of disease development. Deregulation RNA and protein expression of interleukins, chemokines, and lymphokines have been detected in many solid tumors and hematopoetic malignancies, correlating with poor patient prognosis. The current body of literature suggests that in some tumor types, interleukins and chemokines work against the human body by signaling to cancer cells and remodeling the local microenvironment to support the growth, survival, and invasion of primary tumors and enhance metastatic colonization. Some lymphokines are downregulated to suppress tumor progression by enhancing cytotoxic T cell activity and inhibiting tumor cell survival. In this review, we will describe the structure/function of several cytokine families and review our current understanding on the roles and mechanisms of cytokines in tumor progression. In addition, we will also discuss strategies for exploiting the expression and activity of cytokines in therapeutic intervention.