EPI-X4, a CXCR4 antagonist inhibits tumor growth in pancreatic cancer and lymphoma models

Endogenous peptide inhibitor for CXCR4 (EPI-X4) is a CXCR4 antagonist with potential for cancer therapy. It is a processed fragment of serum albumin from the hemofiltrate of dialysis patients. This study reports the efficacy of fifteen EPI-X4 derivatives in pancreatic cancer and lymphoma models. In vitro, the peptides were investigated for antiproliferation (cytotoxicity) by MTT assay. The mRNA expression for CXCR4 and CXCL12 was determined by RT-PCR, chip array and RNA sequencing. Chip array analysis yielded 634 genes associated with CXCR4/CXCL12 signaling. About 21% of these genes correlated with metastasis in the context of cell motility, proliferation, and survival. Expression levels of these genes were altered in pancreatic cancer (36%), lymphoma models (53%) and in patients' data (58%). EPI-X4 derivatives failed to inhibit cell proliferation due to low expression of CXCR4 in vitro, but inhibited tumor growth in the bioassays with significant efficacy. In the pancreatic cancer model, EPI-X4a, f and k inhibited mean tumor growth by > 50% and even caused complete remissions. In the lymphoma model, EPI-X4b, n and p inhibited mean tumor growth by > 70% and caused stable disease. Given the non-toxic and non-immunogenic properties of EPI-X4, these findings underscore its status as a promising therapy of pancreatic cancer and lymphoma and warrant further studies. SIMPLE SUMMARY: This study examined the value of chemokine receptor CXCR4 as an antineoplastic target for the endogenous peptide inhibitor of CXCR4 (EPI-X4), a 12-meric peptide derived from serum albumin. EPI-X4 inhibits CXCR4 interaction with its natural ligand, CXCL12 (SDF1). Therefore, malignancies (including pancreatic cancer and lymphoma) that depend on the CXCR4/CXCL12 pathway for progression can be targeted with EPI-X4. Of 634 genes that were linked to the CXCR4/CXCL12 pathway, 21% were associated with metastasis. In cultured human Suit2-007 pancreatic cancer cells, CXCR4 showed low to undetectable expression, which was why EPI-X4 did not inhibit pancreatic cancer cell proliferation. These findings were different in vivo, where CXCR4 was highly expressed and EPI-X4 inhibited tumor growth in rodents harboring pancreatic cancer or lymphoma. In the pancreatic cancer model, EPI-X4 derivatives a, f and k caused complete remissions, while in lymphomas EPI-X4 derivatives b, n and p caused stable disease.

"Dominolike" Barriers Elimination with an Intratumoral Adenosine-Triphosphate-Supersensitive Nanogel to Enhance Cancer Chemoimmunotherapy

Pathophysiological barriers in "cold" tumors seriously limit the clinical outcomes of chemoimmunotherapy. These barriers distribute in a spatial order in tumors, including immunosuppressive microenvironment, overexpressed chemokine receptors, and dense tumor mesenchyme, which require a sequential elimination in therapeutics. Herein, we reported a "dominolike" barriers elimination strategy by an intratumoral ATP supersensitive nanogel (denoted as BBLZ-945@PAC-PTX) for enhanced chemoimmunotherapy. Once it has reached the tumor site, BBLZ-945@PAC-PTX nanogel undergoes supersensitive collapse triggered by adenosine triphosphate (ATP) in perivascular regions and releases BLZ-945 conjugated albumin (BBLZ-945) to deplete tumor-associated macrophages (TAMs). Deeper spatial penetration of shrunk nanogel (PAC-PTX) could not only block CXCR4 on the cell membrane to decrease immunosuppressive cell recruitment but also internalize into tumor cells for tumor-killing and T cell priming. The strategy of "dominolike" barriers elimination in tumors enables immune cell infiltration for a potentiated immune response and offers a high-responsive treatment opinion for chemoimmunotherapy.

[Retracted] MTSS1 inhibits colorectal cancer metastasis by regulating the CXCR4/CXCL12 signaling axis

Following the publication of the above paper, it was drawn to the Editors' attention by a concerned reader that certain of the Transwell migration assay data shown in Fig. 1B were strikingly similar to data that had appeared in different form in another article by different authors at a different research institution. Furthermore, a number of overlapping data panels were observed comparing among migration assay data shown in Fig. 1B and C and Fig. 7B, such that these data, which were purported to show the results from differently performed experiments, may have been derived from the same original source(s). Owing to the fact that the contentious data in the above article had already been published elsewhere prior to its submission to International Journal of Molecular Medicine, the Editor has decided that this paper should be retracted from the Journal. After having been in contact with the authors, they agreed with the decision to retract the paper. The Editor apologizes to the readership for any inconvenience caused. [International Journal of Molecular Medicine 47: 65, 2021; DOI: 10.3892/ijmm.2021.4898].

Case Report: Altered NK Cell Compartment and Reduced CXCR4 Chemotactic Response of B Lymphocytes in an Immunodeficient Patient With HPV-Related Disease

The study of inborn errors of immunity (IEI) provides unique opportunities to elucidate the microbiome and pathogenic mechanisms related to severe viral infection. Several immunological and genetic anomalies may contribute to the susceptibility to develop Human Papillomavirus (HPV) pathogenesis. They include different acquired immunodeficiencies, EVER1-2 or CIB1 mutations underlying epidermodysplasia verruciformis (EV) syndrome and multiple IEI. Whereas EV syndrome patients are specifically unable to control infections with beta HPV, individuals with IEI show broader infectious and immune phenotypes. The WHIM (warts, hypogammaglobulinemia, infection, and myelokathexis) syndrome caused by gain-of-CXCR4-function mutation manifests by HPV-induced extensive cutaneous warts but also anogenital lesions that eventually progress to dysplasia. Here we report alterations of B and NK cells in a female patient suffering from cutaneous and mucosal HPV-induced lesions due to an as-yet unidentified genetic defect. Despite no detected mutations in CXCR4, B but not NK cells displayed a defective CXCR4-dependent chemotactic response toward CXCL12. In addition, NK cells showed an abnormal distribution with an expanded CD56^bright cell subset and defective cytotoxicity of CD56^dim cells. Our observations extend the clinical and immunological spectrum of IEI associated with selective susceptibility toward HPV pathogenesis, thus providing new insight on the immune control of HPV infection and potential host susceptibility factors.

MTSS1 inhibits colorectal cancer metastasis by regulating the CXCR4/CXCL12 signaling axis

The liver is the most common site of metastasis for colorectal cancer (CRC). Metastasis suppressor 1 (MTSS1), a potential tumor suppressor gene associated with tumor metastasis, has been reported to play an important role in cancer development. The present study aimed to investigate the effects and underlying mechanisms of MTSS1 on the biological behavior of CRC cells both in vitro and in vivo. A CRC mouse model with a high liver metastatic potential was established by injecting mice with SW1116 cells, and the association between MTSS1 expression levels and the metastatic potential of forming liver metastasis lesions was subsequently analyzed. MTSS1 gain‑ and loss‑of‑function experiments were performed by transfecting the CRC cell lines, SW1116 and DLD‑1, with Plvx‑IRES‑ZsGreen1‑MTSS1 plasmid and short hairpin RNA, respectively. Cell proliferation, migration, invasion and cell cycle distribution were analyzed by MTT, Transwell and flow cytometric assays, respectively. To further determine the underlying mechanisms of MTSS1 in CRC, the expression levels of cell surface chemokine C‑X‑C receptor 4 (CXCR4) and its downstream signaling factors, Rac and cell division cycle 42 (CDC42), were analyzed with or without C‑X‑C motif chemokine ligand 12 (CXCL12) stimulation. The results revealed that as the CRC metastatic potential increased, the expression levels of MTSS1 decreased. The overexpression of MTSS1 exerted an inhibitory effect on cell proliferation, migration and invasion, while the knockdown of MTSS1 exerted the opposite effects in vitro. Flow cytometric analysis and western blot analysis demonstrated that MTSS1 negatively regulated the expression levels of cell surface CXCR4 and its downstream signaling pathway activation. On the whole, the results of the present study indicate that MTSS1 may play an important negative role in CRC metastasis and the underlying mechanisms may involve the downregulation of the CXCR4/CXCL12 signaling axis.

New CXCR4 Antagonist Peptide R (Pep R) Improves Standard Therapy in Colorectal Cancer

The chemokine receptor CXCR4 is overexpressed and functional in colorectal cancer. To investigate the role of CXCR4 antagonism in potentiating colon cancer standard therapy, the new peptide CXCR4 antagonist Peptide R (Pep R) was employed. Human colon cancer HCT116 xenograft-bearing mice were treated with chemotherapeutic agents (CT) 5-Fluorouracil (5FU) and oxaliplatin (OX) or 5FU and radio chemotherapy (RT-CT) in the presence of Pep R. After two weeks, CT plus Pep R reduced by 4-fold the relative tumor volume (RTV) as compared to 2- and 1.6-fold reductions induced, respectively, by CT and Pep R. In vitro Pep R addition to CT/RT-CT impaired HCT116 cell growth and further reduced HCT116 and HT29 clonal capability. Thus, the hypothesis that Pep R could target the epithelial mesenchyme transition (EMT) process was evaluated. While CT decreased ECAD and increased ZEB-1 and CD90 expression, the addition of Pep R restored the pretreatment expression. In HCT116 and HT29 cells, CT/RT-CT induced a population of CD133+CXCR4+ cells, supposedly a stem-resistant cancer cell population, while Pep R reduced it. Taken together, the results showed that targeting CXCR4 ameliorates the effect of treatment in colon cancer through inhibition of cell growth and reversal of EMT treatment-induced markers, supporting further clinical studies.

Gr-1highLy6G+Myeloid-derived suppressor cells and their role in a murine model of non-alcoholic steatohepatitis

BACKGROUND AND AIM

Myeloid-derived suppressor cells are a heterogeneous cell population that expand during several pathogenic conditions. However, their role in non-alcoholic steatohepatitis remains unclear. This study aimed to examine the systemic effects of myeloid-derived suppressor cells, to determine the role of Gr-1^highLy6G⁺MDSCs and their correlation with the CXCL12/CXCR4 axis in non-alcoholic steatohepatitis.

METHODS

We established a non-alcoholic steatohepatitis model and detected inflammatory factors IL-6, PGE2, and INF-γ, using an enzyme-linked immunosorbent assay. Proportions of lymphocyte subsets in peripheral blood, CD11b⁺Gr-1⁺myeloid-derived suppressor cells and its subsets in the blood, spleen, liver, and bone marrow were identified using flow cytometry. Adoptive transfer and depletion experiments for MDSCs were performed. Immunohistochemistry, migration assays, and in vivo experiments were used to analyze the role of CXCL12/CXCR4 in non-alcoholic steatohepatitis.

RESULTS

The proportion of CD11b⁺Gr-1⁺MDSCs changed in the bone marrow, spleen, blood, and liver in the non-alcoholic steatohepatitis model. CD4+ and CD8+ T lymphocytes were significantly reduced in non-alcoholic steatohepatitis. Compared with control mice, a significant decrease in ALT and AST levels was observed in Gr-1^highLy6G⁺MDSCs-treated model mice. The migration ability of AMD3100-treated MDSCs was significantly reduced, but was restored as CXCL12 levels increased. CXCL12 and CXCR4 protein levels increased significantly in the non-alcoholic steatohepatitis livers.

CONCLUSIONS

Exogenous Gr-1^highLy6G⁺MDSCs improved liver function during non-alcoholic steatohepatitis. The CXCR4/CXCL12 axis could be the key pathway mediating the attraction of myeloid-derived suppressor cells into the non-alcoholic steatohepatitis environment in mice.

Amide-sulfamide modulators as effective anti-tumor metastatic agents targeting CXCR4/CXCL12 axis

Breast cancer is the most frequently diagnosed malignancy and the second common cause of death in women worldwide. High mortality in breast cancer is frequently associated with metastatic progression rather than the primary tumor itself. It has been recently identified that the CXCR4/CXCL12 axis plays a pivotal role in breast cancer metastasis, especially in directing metastatic cancer cells to CXCL12-riched organs and tissues. Herein, taking the amide-sulfamide as the lead structure, the second-round structural modifications to the sulfamide structure were performed to obtain more active CXCR4 modulators against tumor metastasis. Both in vivo and in vitro experiments illustrated that compound IIIe possessed potent CXCR4 binding affinity, excellent anti-metastatic and anti-angiogenetic activity against breast cancer. More importantly, in a mouse breast cancer lung metastasis model, compound IIIe exerted a significant inhibitory effect on breast cancer metastasis. Taken together, all these positive results demonstrated that developing of CXCR4 modulators is a promising strategy to mediate breast cancer metastasis.

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.

Knockdown of CXCR4 Inhibits CXCL12-Induced Angiogenesis in HUVECs through Downregulation of the MAPK/ERK and PI3K/AKT and the Wnt/β-Catenin Pathways

CXCL12 is an extracellular chemokine binding to cell surface receptor CXCR4. We found that activation of CXCL12/CXCR4 axis stimulated angiogenesis in endothelial cells. Knockdown of CXCR4 in endothelial cells prevented the branch points of angiogenesis. Endothelial cells exposed to CXCL12 presented high level of epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), and matrix metalloproteinase MMP-2, but not in CXCR4 knockdown cells. Further studies revealed that activation of CXCL12/CXCR4 axis in vascular endothelial cells stimulates the angiogenesis through upregulation of the MAPK/ERK and PI3K/AKT and Wnt/β-catenin pathways. Conclusion, downregulation of CXCR4 could inhibit angiogenesis in cancer tissues.

The deficiency of galectin-3 in stromal cells leads to enhanced tumor growth and bone marrow metastasis

Background

Galectin-3 is a multifunctional β-galactoside-binding lectin that once synthesized, is expressed in the nucleus, cytoplasm, cell surface and in the extracellular environment. Because of its unique structure, galectin-3 can oligomerize forming lattice upon binding to multivalent oligossacharides and influence several pathologic events such as tumorigenesis, invasion and metastasis.

Methods

In our study, balb/c Lgals3+/+ and Lgals3−/− female mice were inoculated in the fourth mammary fat pad with 4T1 breast cancer cell line. The primary tumor, inguinal lymph nodes and iliac bone marrow were evaluated 15, 21 and 28 days post-injection. The primary tumor growth was evaluated by measuring the external diameter, internal growth by ultrasound and weight of the excised tumor. The presence of cancer cells in the draining lymph nodes and iliac crest bone marrow were performed by immunohistochemistry, PCR and clonogenic metastatic assay.

Results

In this study we demonstrated that the deletion of galectin-3 in the host affected drastically the in vivo growth rate of 4T1 tumors. The primary tumors in Lgals3−/− mice displayed a higher proliferative rate (p < 0,05), an increased necrotic area (p < 0,01) and new blood vessels with a wider lumen in comparison with tumors from Lgals3+/+ mice (P < 0,05). Moreover, we detected a higher number of 4T1-derived metastatic colonies in the lymph nodes and the bone marrow of Lgals3−/− mice (p < 0,05). Additionally, healthy Lgals3−/− control mice presented an altered spatial distribution of CXCL12 in the bone marrow, which may explain at least in part the initial colonization of this organ in Lgals3−/− injected with 4T1 cells.

Conclusions

Taken together, our results demonstrate for the first time that the absence of galectin-3 in the host microenvironment favors the growth of the primary tumors, the metastatic spread to the inguinal lymph nodes and bone marrow colonization by metastatic 4T1 tumor cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2679-1) contains supplementary material, which is available to authorized users.

Perspective: Cooperation of Nanog, NF-κΒ, and CXCR4 in a regulatory network for directed migration of cancer stem cells

Directed cell migration is a crucial mobility phase of cancer stem cells having stemness and tumorigenic characteristics. It is known that CXCR4 plays key roles in the perception of chemotactic gradients throughout the directed migration of CSCs. There are a number of complex signaling pathways and transcription factors that coordinate with CXCR4/CXCL12 axis during directed migration. In this review, we focus on some transcription factors such as Nanog, NF-κB, and Bmi-1 that cooperate with CXCR4/CXCL12 for the maintenance of stemness and induction of metastasis behavior in cancer stem cells.

Downregulation of the CXCR4/CXCL12 axis blocks the activation of the Wnt/β-catenin pathway in human colon cancer cells

Chemokine CXCL12 is an extracellular chemokine, which binds to its cell surface receptor CXCR4. High expressions of CXCR4 and CXCL12 are associated with biological malignant potential in colon cancers. We aimed to investigate the roles of the CXCR4/CXCL12 axis in activation of the Wnt/β-catenin pathway in the development of colon cancers. Using colon cancer cell line, we performed the RNA interference assay to downregulate the expression of CXCR4. Cells were exposed to CXCL12 and their growth and metastatic activity were examined. Matrix metalloproteinases (MMPs) activity were analyzed by the gelatin zymography assay. Cell migration ability was estimated by assays of scratch wound and transwell chamber. The expression of CXCR4 and molecules relevant to the Wnt/β-catenin pathway were analyzed by the western blotting and real-time PCR assays. Human colon cancer HT-29 cells identified high expression of CXCR4. HT-29 cells highly responded to CXCL12 stimulation, showing the increase of cell proliferation, invasion and migration through the Matrigeal. The secretion and activity of MMP-2 and MMP-9 were also stimulated in HT-29 cells exposure to CXCL12. However, the CXCR4 knockdown HT-29 cells did not response to CXCL12 stimulation. We suggested that the activation of the CXCR4/CXCL12 axis be blocked in the CXCR4 knockdown cells. This study indicated that one key to the role of the CXCR4/CXCL12 axis is activation of the Wnt/β-catenin pathway. Downregulation of the CXCR4/CXCL12 axis thus reduces cancer growth and metastasis. Targeted therapy utilizing the CXCR4/CXCL12 axis could be an effective strategy for treatment of colon cancers.