Metastatic potential of B16-F10 melanoma cells is enhanced by extracellular S100A4 derived from RAW264.7 macrophages

Combined immunochemotherapy achieving targeted co-delivery of chlorogenic acid and doxorubicin by sialic acid-modified liposomes enhances anti-cancer efficacy

Malignant melanoma is a high-grade aggressive skin tumor with an increasing incidence and mortality rates worldwide. Chemotherapeutic drugs such as doxorubicin have limited efficacy against melanoma due to their poor sensitivity, severe side effects, and drug resistance. Recent studies have shown that combinations of immunotherapy and chemotherapy have a synergistic effect in enhancing the anti-tumor effect. Here, we have developed liposomes co-loaded with chlorogenic acid (CA) and doxorubicin (DOX), modified with sialic acid-octadecylamine conjugate (SA-ODA), designated CA-DOX-SAL, that facilitate drug delivery by recognizing Siglec-1 receptor on TAMs. The physicochemical studies revealed the particle size and zeta potential of CA-DOX-SAL as 128.3 ± 0.8 nm and - 4.33 ± 0.50 mV, respectively. In vitro, CA-DOX-SAL demonstrated robust cellular uptake through SA receptor-mediated tumor-associated macrophages (TAM) targeting and exerted greater cytotoxicity on tumor cells. In vivo, targeted liposomes were found to accumulate in the tumor area, leading to an improvement in anti-tumor efficacy. In addition, CA-DOX-SAL effectively inhibited B16F10 melanoma tumor growth by stimulating the transition from tumor-promoting M2-type to anti-tumor M1-type and directly killing tumor cells. Overall, the co-delivery of immunomodulatory CA and chemotherapeutic DOX presents a promising therapeutic strategy to enhance clinical outcomes in the treatment of melanoma.

RAGE Inhibitors for Targeted Therapy of Cancer: A Comprehensive Review

The receptor for advanced glycation end products (RAGE) is a member of the immunoglobulin family that is overexpressed in several cancers. RAGE is highly expressed in the lung, and its expression increases proportionally at the site of inflammation. This receptor can bind a variety of ligands, including advanced glycation end products, high mobility group box 1, S100 proteins, adhesion molecules, complement components, advanced lipoxidation end products, lipopolysaccharides, and other molecules that mediate cellular responses related to acute and chronic inflammation. RAGE serves as an important node for the initiation and stimulation of cell stress and growth signaling mechanisms that promote carcinogenesis, tumor propagation, and metastatic potential. In this review, we discuss different aspects of RAGE and its prominent ligands implicated in cancer pathogenesis and describe current findings that provide insights into the significant role played by RAGE in cancer. Cancer development can be hindered by inhibiting the interaction of RAGE with its ligands, and this could provide an effective strategy for cancer treatment.

Trojan horse treatment based on PEG-coated extracellular vesicles to deliver doxorubicin to melanoma in vitro and in vivo

Tailoring extracellular vesicles (EVs) as targeted drug delivery systems to enhance the therapeutic efficacy showed superior advantage over liposomal therapies. Herein, we developed a novel nanotool for targeting B16.F10 murine melanoma, based on EVs stabilized with Polyethylene glycol (PEG) and loaded with doxorubicin (DOX). Small EVs were efficiently enriched from melanoma cells cultured under metabolic stress by ultrafiltration coupled with size exclusion chromatography (UF-SEC) and characterized by size, morphology, and proteome. To reduce their clearance in vivo, EVs were PEGylated and passively loaded with DOX (PEG-EV-DOX). Our data suggested that the low PEG coverage of EVs might still favor EV surface protein interactions with target proteins from intratumor cells, ensuring their use as "Trojan horses" to deliver DOX to the tumor tissue. Moreover, our results showed a superior antitumor activity of PEG-EV-DOX in B16.F10 murine melanoma models in vivo compared to that exerted by clinically applied liposomal DOX in the same tumor model. The PEG-EV-DOX administration in vivo reduced NF-κB activation and increased BAX expression, suggesting better prognosis of EV-based therapy than liposomal DOX treatment. Collectively, our results highlight the promising potential of EVs as optimal tools for systemic delivery of DOX to solid tumors.

Research trends in pharmacological modulation of tumor-associated macrophages

As one of the most abundant immune cell populations in the tumor microenvironment (TME), tumor-associated macrophages (TAMs) play important roles in multiple solid malignancies, including breast cancer, prostate cancer, liver cancer, lung cancer, ovarian cancer, gastric cancer, pancreatic cancer, and colorectal cancer. TAMs could contribute to carcinogenesis, neoangiogenesis, immune-suppressive TME remodeling, cancer chemoresistance, recurrence, and metastasis. Therefore, reprogramming of the immune-suppressive TAMs by pharmacological approaches has attracted considerable research attention in recent years. In this review, the promising pharmaceutical targets, as well as the existing modulatory strategies of TAMs were summarized. The chemokine-chemokine receptor signaling, tyrosine kinase receptor signaling, metabolic signaling, and exosomal signaling have been highlighted in determining the biological functions of TAMs. Besides, both preclinical research and clinical trials have suggested the chemokine-chemokine receptor blockers, tyrosine kinase inhibitors, bisphosphonates, as well as the exosomal or nanoparticle-based targeting delivery systems as the promising pharmacological approaches for TAMs deletion or reprogramming. Lastly, the combined therapies of TAMs-targeting strategies with traditional treatments or immunotherapies as well as the exosome-like nanovesicles for cancer therapy are prospected.

Role and Mechanisms of RAGE-Ligand Complexes and RAGE-Inhibitors in Cancer Progression

Interactions of the receptor for advanced glycation end product (RAGE) and its ligands in the context of their role in diabetes mellitus, inflammation, and carcinogenesis have been extensively investigated. This review focuses on the role of RAGE-ligands and anti-RAGE drugs capable of controlling cancer progression. Different studies have demonstrated interaction of RAGE with a diverse range of acidic (negatively charged) ligands such as advanced glycation end products (AGEs), high-mobility group box1 (HMGB1), and S100s, and their importance to cancer progression. Some RAGE-ligands displayed effects on anti- and pro-apoptotic proteins through upregulation of the phosphatidylinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR), mitogen-activated protein kinases (MAPKs), matrix metalloproteinases (MMPs), vascular endothelial growth factor (VEGF), and nuclear factor kappa B (NF-κB) pathways, while downregulating p53 in cancer progression. In addition, RAGE may undergo ligand-driven multimodal dimerization or oligomerization mediated through self-association of some of its subunits. We conclude our review by proposing possible future lines of study that could result in control of cancer progression through RAGE inhibition.

Extracellular S100A4 as a key player in fibrotic diseases

Fibrosis is characterized by fibroblast activation, extracellular matrix (ECM) accumulation and infiltration of inflammatory cells that sometimes leads to irreversible organ dysfunction. Considerable evidence now indicates that inflammation plays a critical role in the initiation and progression of organ fibrosis. S100A4 protein, a ubiquitous member of the S100 family, has recently been discovered as a potential factor implicated in fibrotic diseases. S100A4 protein is released at inflammatory site and has a certain biological function to promote cell motility, invasion, ECM remodelling, autophagy and angiogenesis. In addition, extracellular S100A4 is also a potential causation of inflammatory processes and induces the release of cytokines and growth factors under different pathological conditions. Elevated S100A4 level in patients’ serum closely correlates with disease activity in several fibrotic diseases and serves as a useful biomarker for diagnosis and monitoring disease progression. Analyses of knockout mouse models have identified a functional role of extracellular S100A4 protein in fibrotic diseases, suggesting that suppressing its expression, release or function might be a promising therapeutic strategy. This review will focus on the role of extracellular S100A4 as a key regulator of pro‐inflammatory signalling pathways and its relative biological processes involved in the pathogenesis of fibrosis.

The S100A4 Transcriptional Inhibitor Niclosamide Reduces Pro-Inflammatory and Migratory Phenotypes of Microglia: Implications for Amyotrophic Lateral Sclerosis

S100A4, belonging to a large multifunctional S100 protein family, is a Ca²⁺-binding protein with a significant role in stimulating the motility of cancer and immune cells, as well as in promoting pro-inflammatory properties in different cell types. In the CNS, there is limited information concerning S100A4 presence and function. In this study, we analyzed the expression of S100A4 and the effect of the S100A4 transcriptional inhibitor niclosamide in murine activated primary microglia. We found that S100A4 was strongly up-regulated in reactive microglia and that niclosamide prevented NADPH oxidase 2, mTOR (mammalian target of rapamycin), and NF-κB (nuclear factor-kappa B) increase, cytoskeletal rearrangements, migration, and phagocytosis. Furthermore, we found that S100A4 was significantly up-regulated in astrocytes and microglia in the spinal cord of a transgenic rat SOD1-G93A model of amyotrophic lateral sclerosis. Finally, we demonstrated the increased expression of S100A4 also in fibroblasts derived from amyotrophic lateral sclerosis (ALS) patients carrying SOD1 pathogenic variants. These results ascribe S100A4 as a marker of microglial reactivity, suggesting the contribution of S100A4-regulated pathways to neuroinflammation, and identify niclosamide as a possible drug in the control and attenuation of reactive phenotypes of microglia, thus opening the way to further investigation for a new application in neurodegenerative conditions.

The Multifaceted S100A4 Protein in Cancer and Inflammation

The metastasis-promoting S100A4 protein, a member of the S100 family, has recently been discovered as a potent factor implicated in various inflammation-associated diseases. S100A4 is involved in a range of biological functions such as angiogenesis, cell differentiation, apoptosis, motility, and invasion. Moreover, S100A4 is also a potent trigger of inflammatory processes and induces the release of cytokines and growth factors under different pathological conditions.Indeed, the release of S100A4 upon stress and mainly its pro-inflammatory role emerges as the most decisive activity in disease development, such as rheumatoid arthritis (RA), systemic sclerosis (SSc) allergy, psoriasis, and cancer. In the scope of this review, we will focus on the role of S100A4 as a mediator of pro-inflammatory pathways and its associated biological processes involved in the pathogenesis of various human noncommunicable diseases (NCDs) including cancer.

Mannose functionalized plain and endosomolytic nanocomposite(s)-based approach for the induction of effective antitumor immune response in C57BL/6 mice melanoma model

The goal of present study to assess the antigen specific immunopotentiation effect of mannose functionalized endosomolytic and conventional nanocomposite(s) based combination approach using C57BL/6 mice melanoma model. Endosomolytic and conventional nanocomposite(s) were prepared by double emulsification method. The optimized formulation was extensively characterized for average particle size, zeta potential and PDI of nanocomposite(s) which were measured in range of ≈200 nm, 0.111 ± 0.024, -23.4 ± 2.0 mV, respectively. pH-dependent morphological changes in the surface of MRPRPNs and PRPNs were analyzed by using surface electron microscopy at different time intervals. The cellular uptake assessment of developed formulations were followed by using RAW 264.7 macrophage cell lines. Results revealed that after immunizing B16F10 melanoma cells implanted C57BL/6 mice with combination [endosomolytic and conventional nanocomposite(s)] of nanocomposite(s), a significant increase in the interleukins level i.e. IL-2, IFN-ϒ, IL-12 and IL-6 and OVA Ag(s) specific antibody responses were recorded. Consequently, a strong immunological response was elicited with specific polarization contributing to humoral and activation of CD8⁺ to cellular responses. Finding of histological examination also support the potential of therapeutic outcome. The present approach based on mannose surface functionalization for targeting to antigen presenting cells and pH-dependent prompt endosomal release and escape can be a promising system for efficient cancer immunotherapy.

Combination therapy of simvastatin and 5, 6-dimethylxanthenone-4-acetic acid synergistically suppresses the aggressiveness of B16.F10 melanoma cells

The major drawback of current anti-angiogenic therapies is drug resistance, mainly caused by overexpression of the transcription factor, hypoxia-inducible factor 1α (HIF-1α) as a result of treatment-induced hypoxia, which stimulates cancer cells to develop aggressive and immunosuppressive phenotypes. Moreover, the cancer cell resistance to anti-angiogenic therapies is deeply mediated by the communication between tumor cells and tumor-associated macrophages (TAMs)-the most important microenvironmental cells for the coordination of all supportive processes in tumor development. Thus, simultaneous targeting of TAMs and cancer cells could improve the outcome of the anti-angiogenic therapies. Since our previous studies proved that simvastatin (SIM) exerts strong antiproliferative actions on B16.F10 murine melanoma cells via reduction of TAMs-mediated oxidative stress and inhibition of intratumor production of HIF-1α, we investigated whether the antitumor efficacy of the anti-angiogenic agent-5,6-dimethylxanthenone-4-acetic acid (DMXAA) could be improved by its co-administration with the lipophilic statin. Our results provide confirmatory evidence for the ability of the combined treatment to suppress the aggressive phenotype of the B16.F10 melanoma cells co-cultured with TAMs under hypoxia-mimicking conditions in vitro. Thus, proliferation and migration capacity of the melanoma cells were strongly decelerated after the co-administration of SIM and DMXAA. Moreover, our data suggested that the anti-oxidant action of the combined treatment, as a result of melanogenesis stimulation, might be the principal cause for the simultaneous suppression of key molecules involved in melanoma cell aggressiveness, present in melanoma cells (HIF-1α) as well as in TAMs (arginase-1). Finally, the concomitant suppression of these proteins might have contributed to a very strong inhibition of the angiogenic capacity of the cell co-culture microenvironment.

Embigin Promotes Prostate Cancer Progression by S100A4-Dependent and-Independent Mechanisms

Embigin, a transmembrane glycoprotein belonging to the immunoglobulin superfamily, is involved in prostate and mammary gland development. As embigin’s roles in cancer remain elusive, we studied its biological functions and interaction with extracellular S100A4 in prostate cancer progression. We found by a pull-down assay that embigin is a novel receptor for S100A4, which is one of the vital cancer microenvironment milleu. Binding of extracellular S100A4 to embigin mediates prostate cancer progression by inhibition of AMPK activity, activation of NF-κB, MMP9 and mTORC1 signaling, and inhibition of autophagy, which increase prostate cancer cell motility. We also found that embigin promotes prostate cancer growth, spheroid- and colony-forming ability, and survival upon chemotherapy independently of S100A4. An in vivo growth mouse model confirmed the importance of embigin and its cytoplasmic tail in mediating prostate tumor growth. Moreover, embigin and p21^WAF1 can be used to predict survival of prostate cancer patients. Our results demonstrated for the first time that the S100A4-embigin/AMPK/mTORC1/p21^WAF1 and NF-κB/MMP9 axis is a vital oncogenic molecular cascade for prostate cancer progression. We proposed that embigin and p21^WAF1 could be used as prognostic biomarkers and a strategy to inhibit S100A4-embigin binding could be a therapeutic approach for prostate cancer patients.

Therapeutic effects of tyroserleutide on lung metastasis of human hepatocellular carcinoma SK-HEP-1 and its mechanism affecting ICAM-1 and MMP-2 and -9

BACKGROUND

Tyroserleutide (YSL) inhibits the growth and metastasis of human hepatocellular carcinoma (HCC). This paper studied the effect of YSL on metastasis of human HCC and investigated its mechanisms.

METHODS

In vivo, experimental lung metastasis models of human HCC SK-HEP-1 cells in nude mice were established, and In vitro, the proliferation, adhesion and invasion of SK-HEP-1 cells were detected.

RESULTS

In vivo, YSL significantly inhibited the metastasis of human HCC. In vitro, YSL significantly inhibited the proliferation, adhesion and invasion of SK-HEP-1 cells. Through analyses with reverse transcription PCR (RT-PCR) and Western blot, we observed that YSL significantly inhibited the expressions of ICAM-1 in SK-HEP-1 cells. Through RT-PCR, Western blot and zymography methods, YSL was discovered to decrease the mRNA level, protein expression and activity of MMP-2 and -9 in SK-HEP-1 cells.

CONCLUSION

We concluded that YSL could inhibit tumor growth and metastasis of human HCC SK-HEP-1 cells.

Ousting RAGE in melanoma: A viable therapeutic target?

Melanoma remains an important health concern, given the steady increase in incidence and acquisition of resistance to systemic therapies. The receptor for advanced glycation end products (RAGE) initially identified for its binding to advanced glycation end products was subsequently acknowledged as a pattern recognition receptor given its ability to recognize similar structural elements within numerous ligands. Recent studies have elucidated a plausible role of RAGE in melanoma progression through modulation of inflammatory, proliferative and invasive cellular responses. Several of its ligands including the S100 proteins and HMGB1 are being investigated for their involvement in melanoma metastasis and as potential biomarkers of the disease. Targeting RAGE signaling represents a viable therapeutic strategy which remains underexplored in cutaneous malignancies. Here we have summarized current knowledge on the functionality of RAGE with special focus on specific ligands enumerated in various in vitro and in vivo melanoma models.

Deficiency in Calcium-Binding Protein S100A4 Impairs the Adjuvant Action of Cholera Toxin

The calcium-binding protein S100A4 has been described to promote pathological inflammation in experimental autoimmune and inflammatory disorders and in allergy and to contribute to antigen presentation and antibody response after parenteral immunization with an alum-adjuvanted antigen. In this study, we extend these findings by demonstrating that mice lacking S100A4 have a defective humoral and cellular immune response to mucosal (sublingual) immunization with a model protein antigen [ovalbumin (OVA)] given together with the strong mucosal adjuvant cholera toxin (CT), and that this impairment is due to defective adjuvant-stimulated antigen presentation by antigen-presenting cells. In comparison to wild-type (WT) mice, mice genetically lacking S100A4 had reduced humoral and cellular immune responses after immunization with OVA plus CT, including a complete lack of detectable germinal center reaction. Further, when stimulated in vitro with OVA plus CT, S100A4^−/− dendritic cells (DCs) showed impaired responses in several CT-stimulated immune regulatory molecules including the co-stimulatory molecule CD86, inflammasome-associated caspase-1 and IL-1β. Coculture of OVA-specific OT-II T cells with S100A4^−/− DCs that had been pulse incubated with OVA plus CT resulted in impaired OT-II T cell proliferation and reduced production of Th1, Th2, and Th17 cytokines compared to similar cocultures with WT DCs. In accordance with these findings, transfection of WT DCs with S100A4-targeting small interfering RNA (siRNA) but not mock-siRNA resulted in significant reductions in the expression of caspase-1 and IL-1β as well as CD86 in response to CT. Importantly, also engraftment of WT DCs into S100A4^−/− mice effectively restored the immune response to immunization in the recipients. In conclusion, our results demonstrate that deficiency in S100A4 has a strong impact on the development of both humoral and cellular immunity after mucosal immunization using CT as adjuvant.

Extracellular S100A4 affects endothelial cell integrity and stimulates transmigration of A375 melanoma cells

High extracellular S100A4 level proves a specific characteristic of some cancer cases, including malignant melanoma. Concerning the latter, extracellular S100A4 in an autocrine manner was shown to promote prometastatic activation of A375 cells by interaction with the receptor for advanced glycation endproducts (RAGE). We hypothesized that interaction of extracellular S100A4 with RAGE in a paracrine manner will affect endothelial cell (EC) integrity thus further promoting melanoma metastasis. We investigated the influence of recombinant and cell (A375)-derived S100A4 on junction protein expression and EC (hCMEC/D3) integrity by measuring transendothelial electrical resistance (TEER). Decrease of TEER and diminished expression of both occludin and VE-cadherin revealed the loss of EC integrity. Transmigration of transgenic A375 cells (A375-hS100A4/A375-hRAGE) through the EC monolayer was significantly higher compared to wild-type A375 cells, and was substantially decreased by sRAGE. A pilot study in mice, intracardially injected with A375-hS100A4 or A375-hRAGE cells, showed lower survival rates and a higher incidence of metastases compared to wild-type A375 cells. Tumor development was mostly located in the brain, bones, and ovaries. These findings provide further evidence on extracellular S100A4 as paracrine mediator of prometastatic endothelial dysfunction involving its interaction with RAGE.

Interaction of extracellular S100A4 with RAGE prompts prometastatic activation of A375 melanoma cells

S100A4, a member of the S100 protein family of EF-hand calcium-binding proteins, is overexpressed in various tumour entities, including melanoma, and plays an important role in tumour progression. Several studies in epithelial and mesenchymal tumours revealed a correlation between extracellular S100A4 and metastasis. However, exact mechanisms how S100A4 stimulates metastasis in melanoma are still unknown. From a pilot experiment on baseline synthesis and secretion of S100A4 in human melanoma cell lines, which are in broad laboratory use, A375 wild-type cells and, additionally, newly generated A375 cell lines stably transfected with human S100A4 (A375-hS100A4) or human receptor for advanced glycation endproducts (A375-hRAGE), were selected to investigate the influence of extracellular S100A4 on cell motility, adhesion, migration and invasion in more detail. We demonstrated that A375 cells actively secrete S100A4 in the extracellular space via an endoplasmic reticulum-Golgi-dependent pathway. S100A4 overexpression and secretion resulted in prometastatic activation of A375 cells. Moreover, we determined the influence of S100A4-RAGE interaction and its blockade on A375, A375-hS100A4, A375-hRAGE cells, and showed that interaction of RAGE with extracellular S100A4 contributes to the observed activation of A375 cells. This investigation reveals additional molecular targets for therapeutic approaches aiming at blockade of ligand binding to RAGE or RAGE signalling to inhibit melanoma metastasis.

Increased Notch Signaling Enhances Radioresistance of Malignant Stromal Cells Induced by Glioma Stem/ Progenitor Cells

Background

Host malignant stromal cells induced by glioma stem/progenitor cells were revealed to be more radiation-resistant than the glioma stem/progenitor cells themselves after malignant transformation in nude mice. However, the mechanism underlying this phenomenon remains unclear.

Methods

Malignant stromal cells induced by glioma stem/progenitor cell 2 (GSC-induced host brain tumor cells, ihBTC2) were isolated and identified from the double color-coded orthotopic glioma nude mouse model. The survival fraction at 2 Gy (SF2) was used to evaluate the radiation resistance of ihBTC2, the human glioma stem/progenitor cell line SU3 and its radiation-resistant sub-strain SU3-5R and the rat C6 glioma cell line. The mRNA of Notch 1 and Hes1 from ihBTC2 cells were detected using qPCR before and after 4 Gy radiation. The expression of the Notch 1, pAkt and Bcl-2 proteins were investigated by Western blot. To confirm the role of the Notch pathway in the radiation resistance of ihBTC2, Notch signaling blocker gamma secretase inhibitors (GSIs) were used.

Results

The ihBTC2 cells had malignant phenotypes, such as infinite proliferation, hyperpentaploid karyotype, tumorigenesis in nude mice and expression of protein markers of oligodendroglia cells. The SF2 of ihBTC2 cells was significantly higher than that of any other cell line (P<0.05, n = 3). The expression of Notch 1 and Hes1 mRNAs from ihBTC2 cells was significantly increased after radiation. Moreover, the Notch 1, pAkt and Bcl-2 proteins were significantly increased after radiation (P<0.05, n = 3). Inhibition of Notch signaling markedly enhanced the radiosensitivity of ihBTC2 cells.

Conclusions

In an orthotopic glioma model, the malignant transformation of host stromal cells was induced by glioma stem/progenitor cells. IhBTC2 cells are more radiation-resistant than the glioma stem/progenitor cells, which may be mediated by activation of the Notch signaling pathway.

The role of S100 proteins and their receptor RAGE in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with low survival rates. Current therapeutic treatments have very poor response rates due to the high inherent chemoresistance of the pancreatic-cancer cells. Recent studies have suggested that the receptor for advanced glycation end products (RAGE) and its S100 protein ligands play important roles in the progression of PDAC. We will discuss the potential role of S100 proteins and their receptor, RAGE, in the development and progression of pancreatic cancer.

Conditioning solid tumor microenvironment through inflammatory chemokines and S100 family proteins

Recently, there has been growing attention to the role of the tumor microenvironment (TME) in cancer growth, metastasis and emergence of chemotherapy resistance. Stromal and tumor cells make up the TME and interact with each other through a complex cross-talk manner. This interaction is facilitated by a variety of growth factors, cytokines, chemokines and S100 proteins. In this review, we focus on chemokines and their cognate receptors in regulating the tumorigenic process. Chemokines are cytokines that have chemotactic potential. Chemokine receptors are expressed on tumor cells and stromal cells. Chemokines and their cognate receptors modulate tumor growth and metastasis in a paracrine and autocrine manner. They play a major role in the modulation of stromal cell recruitment, angiogenic potential, cancer cell proliferation, survival, adhesion, invasion and metastasis to distant sites. In addition, a new class of calcium binding family S100 proteins has been getting attention as they play significant roles in tumor progression and metastasis by modulating TME. Here, we highlight recent developments regarding the inflammatory chemokine/S100 protein systems in the TME. We also focus on how chemokines/S100 proteins, through their role in the TME, modulate cancer cell ability to grow, proliferate, invade and metastasize to different organs. This review highlights the possibility of using the chemokine/chemokine receptor axis as a promising strategy in cancer therapy, the current difficulties in achieving this goal, and how it could be overcome for successful future therapeutic intervention.