Six1 promotes colorectal cancer growth and metastasis by stimulating angiogenesis and recruiting tumor-associated macrophages

The role of homeobox gene Six1 in cancer progression and its potential as a therapeutic target: A review

The sine oculis homeobox gene 1 (Six1), a member of the Six transcription factor family, specifically binds to defined DNA regions, regulates target gene expression, and plays a crucial role in various tissue and organ development processes. Moreover, Six1 is a critical factor in cancer progression and prognosis making it a central focus in cancer research. Consequently, a comprehensive review of involvement of the Six1 gene in cancer research has a high relevance. This review synthesizes findings from other researches, examines the gene structure and protein functionality of Six1, summarizes its relationship with various cancers, elucidates its mechanisms in promoting tumor progression and development, explores potential possibilities for targeting Six1 as a therapeutic approach for cancer treatment. Six1 is correlated with tumor malignancy and poor prognosis, plays a critical role in promoting tumor cell proliferation, invasion, metastasis, and energy metabolism. Targeting Six1 degradation or expression can potentially suppress tumor progression. This review aims to enhance our understanding of the function and significance of Six1 in cancers while providing a valuable reference for Six1-based cancer diagnosis, prognosis, and therapeutic interventions. This knowledge will facilitate more in-depth oncology research related to Six1, particularly in identifying drug resistance mechanisms and developing precision-targeted therapies.

Targeting tumor-associated macrophages in colon cancer: mechanisms and therapeutic strategies

Colon cancer (CC) remains a primary contributor to cancer-related fatalities worldwide, driven by difficulties in early diagnosis and constrained therapeutic options. Recent studies underscore the importance of the tumor microenvironment (TME), notably tumor-associated macrophages (TAMs), in fostering malignancy progression and therapy resistance. Through their inherent plasticity, TAMs facilitate immunosuppression, angiogenic processes, metastatic spread, and drug tolerance. In contrast to M1 macrophages, which promote inflammatory and tumoricidal responses, M2 macrophages support tumor expansion and dissemination by exerting immunosuppressive and pro-angiogenic influences. Consequently, manipulating TAMs has emerged as a potential avenue to enhance treatment effectiveness. This review outlines the origins, polarization states, and functions of TAMs in CC, highlights their role in driving tumor advancement, and surveys ongoing efforts to target these cells for better patient outcomes. Emerging therapeutic strategies aimed at modulating TAM functions - including depletion strategies, reprogramming approaches that shift M2-polarized TAMs toward an M1 phenotype, and inhibition of key signaling pathways sustaining TAM-mediated immunosuppression-are currently under active investigation. These approaches hold promise in overcoming TAM - induced resistance and improving immunotherapeutic efficacy in CC.

Brd7 loss reawakens dormant metastasis initiating cells in lung by forging an immunosuppressive niche

Metastasis in cancer is influenced by epigenetic factors. Using an in vivo screen, we demonstrate that several subunits of the polybromo-associated BAF (PBAF) chromatin remodeling complex, particularly Brd7, are required for maintaining breast cancer metastatic dormancy in the lungs of female mice. Brd7 loss induces metastatic reawakening, along with modifications in epigenomic landscapes and upregulated oncogenic signaling. Breast cancer cells harboring Brd7 inactivation also reprogram the surrounding immune microenvironment by downregulating MHC-1 expression and promoting a pro-metastatic cytokine profile. Flow cytometric and single-cell analyses reveal increased levels of pro-tumorigenic inflammatory and transitional neutrophils, CD8+ exhausted T cells, and CD4+ stress response T cells in lungs from female mice harboring Brd7-deficient metastases. Finally, attenuating this immunosuppressive milieu by neutrophil depletion, neutrophil extracellular trap (NET) inhibition, or immune checkpoint therapy abrogates metastatic outgrowth. These findings implicate Brd7 and PBAF in triggering metastatic outgrowth in cancer, pointing to targetable underlying mechanisms involving specific immune cell compartments.

Sine oculis homeobox homolog family function in gastrointestinal cancer: Progression and comprehensive analysis

The sine oculis homeobox homolog (SIX) family, a group of transcription factors characterized by a conserved DNA-binding homology domain, plays a critical role in orchestrating embryonic development and organogenesis across various organisms, including humans. Comprising six distinct members, from SIX1 to SIX6, each member contributes uniquely to the development and differentiation of diverse tissues and organs, underscoring the versatility of the SIX family. Dysregulation or mutations in SIX genes have been implicated in a spectrum of developmental disorders, as well as in tumor initiation and progression, highlighting their pivotal role in maintaining normal developmental trajectories and cellular functions. Efforts to target the transcriptional complex of the SIX gene family have emerged as a promising strategy to inhibit tumor development. While the development of inhibitors targeting this gene family is still in its early stages, the significant potential of such interventions holds promise for future therapeutic advances. Therefore, this review aimed to comprehensively explore the advancements in understanding the SIX family within gastrointestinal cancers, focusing on its critical role in normal organ development and its implications in gastrointestinal cancers, including gastric, pancreatic, colorectal cancer, and hepatocellular carcinomas. In conclusion, this review deepened the understanding of the functional roles of the SIX family and explored the potential of utilizing this gene family for the diagnosis, prognosis, and treatment of gastrointestinal cancers.

The Role of Macrophages in Various Types of Tumors and the Possibility of Their Use as Targets for Antitumor Therapy

In solid tumors, tumor-associated macrophages (TAMs) are one of the most numerous populations and play an important role in the processes of tumor cell invasion, metastasis, and angiogenesis. Therefore, TAMs are considered promising diagnostic and prognostic biomarkers of tumors, and many attempts have been made to influence these cells as part of antitumor therapy. There are several key principles of action on ТАМs: the inhibition of monocyte/macrophage transition; the destruction of macrophages; the reprogramming of macrophage phenotypes (polarization of M2 macrophages to M1); the stimulation of phagocytic activity of macrophages and CAR-M therapy. Despite the large number of studies in this area, to date, there are no adequate approaches using antitumor therapy based on alterations in TAM functioning that would show high efficacy when administered in a mono-regimen for the treatment of malignant neoplasms. Studies devoted to the evaluation of the efficacy of drugs acting on TAMs are characterized by a small sample and the large heterogeneity of patient groups; in addition, in such studies, chemotherapy or immunotherapy is used, which significantly complicates the evaluation of the effectiveness of the agent acting on TAMs. In this review, we attempted to systematize the evidence on attempts to influence TAMs in malignancies such as lung cancer, breast cancer, colorectal cancer, cervical cancer, prostate cancer, gastric cancer, head and neck squamous cell cancer, and soft tissue sarcomas.

Research progress of tumor-associated macrophages in immune checkpoint inhibitor tolerance in colorectal cancer

The relevant mechanism of tumor-associated macrophages (TAMs) in the treatment of colorectal cancer patients with immune checkpoint inhibitors (ICIs) is discussed, and the application prospects of TAMs in reversing the treatment tolerance of ICIs are discussed to provide a reference for related studies. As a class of drugs widely used in clinical tumor immunotherapy, ICIs can act on regulatory molecules on cells that play an inhibitory role-immune checkpoints-and kill tumors in the form of an immune response by activating a variety of immune cells in the immune system. The sensitivity of patients with different types of colorectal cancer to ICI treatment varies greatly. The phenotype and function of TAMs in the colorectal cancer microenvironment are closely related to the efficacy of ICIs. ICIs can regulate the phenotypic function of TAMs, and TAMs can also affect the tolerance of colorectal cancer to ICI therapy. TAMs play an important role in ICI resistance, and making full use of this target as a therapeutic strategy is expected to improve the immunotherapy efficacy and prognosis of patients with colorectal cancer.

Monoacylglycerol acyltransferase-2 inhibits colorectal carcinogenesis in APCmin+/- mice

Monoacylglycerol acyltransferase-2 (MOGAT2), encodes MOGAT enzyme in the re-synthesis of triacylglycerol and protects from metabolism disorders. While, its precise involvement in colorectal cancer (CRC) progression remains inadequately understood. Our study demonstrated that knockout of Mogat2 in Apcmin/+ mice expedited intestinal tumor growth and progression, indicating that Mogat2 plays a tumor-suppressing role in CRC. Mechanically, Mogat2 deletion resulted in a significant alter the gut microbiota, while Fecal Microbiota Transplantation (FMT) experiments demonstrated that the gut microbiota in Mogat2 deleted mice promoted tumor growth. Furthermore, we identified Mogat2 as a functional regulator suppressing CRC cell proliferation and tumor growth by inhibiting the NF-κB signaling pathway in vivo. Collectively, these results provide novel insights into the protective double roles of Mogat2, inhibiting of NF-κB pathway and keeping gut microbiota homeostasis in colorectal cancer, which may help the development of novel cancer treatments for CRC.

Targeting sine oculis homeoprotein 1 (SIX1): A review of oncogenic roles and potential natural product therapeutics

Sine oculis homeoprotein 1 (SIX1), a prominent representative of the homeodomain transcription factors within the SIX family, has attracted significant interest owing to its role in tumorigenesis, cancer progression, and prognostic assessments. Initially recognized for its pivotal role in embryonic development, SIX1 has emerged as a resurgent factor across a diverse set of mammalian cancers. Over the past two decades, numerous investigations have emphasized SIX1's dual significance as a developmental regulator and central player in oncogenic processes. A mounting body of evidence links SIX1 to the initiation of diverse cancers, encompassing enhanced cellular metabolism and advancement. This review provides an overview of the multifaceted roles of SIX1 in both normal development and oncogenic processes, emphasizing its importance as a possible therapeutic target and prognostic marker. Additionally, this review discusses the natural product agents that inhibit various pro-oncogenic mechanisms associated with SIX1.

GSK3β phosphorylates Six1 transcription factor and regulates its APC/CCdh1 mediated proteosomal degradation

Sine oculis homeobox homolog 1 (Six1) is a developmentally important transcription factor that regulates cellular proliferation, apoptosis, and dissemination during embryogenesis. Six1 overexpression as reported in multiple cancers modulates expression of a repertoire of its target genes causing an increase in proliferation, metastasis and survival of cancer cells. Six1 exists as a cell cycle regulated nuclear phosphoprotein and its cellular turnover is regulated by APC/C (Anaphase promoting complex / Cyclosome) complex mediated proteolysis. However, the kinases that regulate Six1 proteolysis have not been identified and the mechanistic details that cause its overproduction in various cancers are lacking. Here, we report that Six1 is a physiological GSK3β substrate. GSK3β interacts with Six1 and phosphorylates it at Ser221 within the conserved consensus sequence in its carboxy terminus. Using pharmacological inhibition, siRNA mediated knockdown and protein overexpression of GSK3β; we show that GSK3β regulates Six1 protein stability. Pulse chase analysis of Six1 revealed that GSK3β regulates its ubiquitin proteolysis such that Six1 phosphomimicking mutant (Six1S221E) for Ser221 site had dramatically increased half-life than its phosphodeficient (Six1S221A) and wild type variants. Furthermore, we demonstrate that GSK3β rescues Six1 from APC dependent proteolysis by regulating its binding with APC/C co-activator protein Cdh1. Importantly, strong positive correlation exists between GSK3β and Six1 protein levels throughout the cell cycle and in multiple cancers indicating that GSK3β activation may in part contribute to Six1 overproduction in a subset of human cancers.

Crosstalk between colorectal CSCs and immune cells in tumorigenesis, and strategies for targeting colorectal CSCs

Cancer immunotherapy has emerged as a promising strategy in the treatment of colorectal cancer, and relapse after tumor immunotherapy has attracted increasing attention. Cancer stem cells (CSCs), a small subset of tumor cells with self-renewal and differentiation capacities, are resistant to traditional therapies such as radiotherapy and chemotherapy. Recently, CSCs have been proven to be the cells driving tumor relapse after immunotherapy. However, the mutual interactions between CSCs and cancer niche immune cells are largely uncharacterized. In this review, we focus on colorectal CSCs, CSC-immune cell interactions and CSC-based immunotherapy. Colorectal CSCs are characterized by robust expression of surface markers such as CD44, CD133 and Lgr5; hyperactivation of stemness-related signaling pathways, such as the Wnt/β-catenin, Hippo/Yap1, Jak/Stat and Notch pathways; and disordered epigenetic modifications, including DNA methylation, histone modification, chromatin remodeling, and noncoding RNA action. Moreover, colorectal CSCs express abnormal levels of immune-related genes such as MHC and immune checkpoint molecules and mutually interact with cancer niche cells in multiple tumorigenesis-related processes, including tumor initiation, maintenance, metastasis and drug resistance. To date, many therapies targeting CSCs have been evaluated, including monoclonal antibodies, antibody‒drug conjugates, bispecific antibodies, tumor vaccines adoptive cell therapy, and small molecule inhibitors. With the development of CSC-/niche-targeting technology, as well as the integration of multidisciplinary studies, novel therapies that eliminate CSCs and reverse their immunosuppressive microenvironment are expected to be developed for the treatment of solid tumors, including colorectal cancer.

Tumor-associated macrophages in colorectal cancer metastasis: molecular insights and translational perspectives

Metastasis is the leading cause of high mortality in colorectal cancer (CRC), which is not only driven by changes occurring within the tumor cells, but is also influenced by the dynamic interaction between cancer cells and components in the tumor microenvironment (TME). Currently, the exploration of TME remodeling and its impact on CRC metastasis has attracted increasing attention owing to its potential to uncover novel therapeutic avenues. Noteworthy, emerging studies suggested that tumor-associated macrophages (TAMs) within the TME played important roles in CRC metastasis by secreting a variety of cytokines, chemokines, growth factors and proteases. Moreover, TAMs are often associated with poor prognosis and drug resistance, making them promising targets for CRC therapy. Given the prognostic and clinical value of TAMs, this review provides an updated overview on the origin, polarization and function of TAMs, and discusses the mechanisms by which TAMs promote the metastatic cascade of CRC. Potential TAM-targeting techniques for personalized theranostics of metastatic CRC are emphasized. Finally, future perspectives and challenges for translational applications of TAMs in CRC development and metastasis are proposed to help develop novel TAM-based strategies for CRC precision medicine and holistic healthcare.

Adipose Mesenchymal Stem Cell-derived Exosomes Enhanced Glycolysis through the SIX1/HBO1 Pathway against Oxygen and Glucose Deprivation Injury in Human Umbilical Vein Endothelial Cells

BACKGROUND

Angiogenesis and energy metabolism mediated by adipose mesenchymal stem cell-derived exosomes (AMSC-exos) are promising therapeutics for vascular diseases.

OBJECTIVES

The current study aimed to explore whether AMSC-exos have therapeutic effects on oxygen and glucose deprivation (OGD) human umbilical vein endothelial cells (HUVECs) injury by modulating the SIX1/HBO1 signaling pathway to upregulate endothelial cells (E.C.s) glycolysis and angiogenesis.

METHODS

AMSC-exos were isolated and characterized following standard protocols. AMSC-exos cytoprotective effects were evaluated in the HUVECs-OGD model. The proliferation, migration, and tube formation abilities of HUVECs were assessed. The glycolysis level was evaluated by detecting lactate production and ATP synthesis. The expressions of HK2, PKM2, VEGF, HIF-1α, SIX1, and HBO1 were determined by western blotting, and finally, the SIX1 overexpression vector or small interfering RNA (siRNA) was transfected into HUVECs to assess the change in HBO1 expression.

RESULTS

Our study revealed that AMSC-exos promotes E.C.s survival after OGD, reducing E.C.s apoptosis while strengthening E.C.'s angiogenic ability. AMSC-exos enhanced glycolysis and reduced OGD-induced ECs injury by modulation of the SIX1/HBO1 signaling pathway, which is a novel anti-endothelial cell injury role of AMSC-exos that regulates glycolysis via activating the SIX1/HBO1 signaling pathway.

CONCLUSION

The current study findings demonstrate a useful angiogenic therapeutic strategy for AMSC-exos treatment in vascular injury, thus providing new therapeutic ideas for treating ischaemic diseases.

SIX1 amplification modulates stemness and tumorigenesis in breast cancer

BACKGROUND

Sine oculis homeobox homolog 1 (SIX1) is a transcription factor that has recently been identified as a crucial regulator of embryonic development and tumorigenesis. SIX1 is upregulated in different types of tumors, including breast cancer. However, the role and mechanism of SIX1 upregulation in breast cancer carcinogenesis remains uncertain.

METHODS

In this study, we utilized various databases such as UALCAN, TCGA, STRING, and Kaplan-Meier Plotter to investigate the mRNA expression, prognosis, transcriptional profile changes, signal pathway rewiring, and interaction with cancer stem cells of SIX1 in breast cancer. We also conducted both in vitro and in vivo experiments to validate its positive regulation effect on breast cancer stem cells.

RESULTS

Our findings demonstrated that the expression of SIX1 varies among different subtypes of breast cancer and that it upregulates breast cancer grading and lymph node metastasis. Besides, SIX1 participates in the rewiring of several cancer signaling pathways, including estrogen, WNT, MAPK, and other pathways, and interacts with cancer stem cells. SIX1 showed a significant positive correlation with breast cancer stem cell markers such as ALDH1A1, EPCAM, ITGB1, and SOX2. Moreover, our in vitro and in vivo experiments confirmed that SIX1 can promote the increase in the proportion of stem cells and tumor progression.

CONCLUSIONS

Altogether, our results suggest that SIX1 plays an essential regulatory role in breast cancer's occurrence, and its amplification can be utilized as a diagnostic and prognostic predictor. The interaction between SIX1 and cancer stem cells may play a critical role in regulating breast cancer's initiation and metastasis.

Organoids and metastatic orthotopic mouse model for mismatch repair-deficient colorectal cancer

Background

Genome integrity is essential for the survival of an organism. DNA mismatch repair (MMR) genes (e.g., MLH1, MSH2, MSH6, and PMS2) play a critical role in the DNA damage response pathway for genome integrity maintenance. Germline mutations of MMR genes can lead to Lynch syndrome or constitutional mismatch repair deficiency syndrome, resulting in an increased lifetime risk of developing cancer characterized by high microsatellite instability (MSI-H) and high mutation burden. Although immunotherapy has been approved for MMR-deficient (MMRd) cancer patients, the overall response rate needs to be improved and other management options are needed.

Methods

To better understand the biology of MMRd cancers, elucidate the resistance mechanisms to immune modulation, and develop vaccines and therapeutic testing platforms for this high-risk population, we generated organoids and an orthotopic mouse model from intestine tumors developed in a Msh2-deficient mouse model, and followed with a detailed characterization.

Results

The organoids were shown to be of epithelial origin with stem cell features, to have a high frameshift mutation frequency with MSI-H and chromosome instability, and intra- and inter-tumor heterogeneity. An orthotopic model using intra-cecal implantation of tumor fragments derived from organoids showed progressive tumor growth, resulting in the development of adenocarcinomas mixed with mucinous features and distant metastasis in liver and lymph node.

Conclusions

The established organoids with characteristics of MSI-H cancers can be used to study MMRd cancer biology. The orthotopic model, with its distant metastasis and expressing frameshift peptides, is suitable for evaluating the efficacy of neoantigen-based vaccines or anticancer drugs in combination with other therapies.

Macrophage's role in solid tumors: two edges of a sword

The tumor microenvironment is overwhelmingly dictated by macrophages, intimately affiliated with tumors, exercising pivotal roles in multiple processes, including angiogenesis, extracellular matrix reconfiguration, cellular proliferation, metastasis, and immunosuppression. They further exhibit resilience to chemotherapy and immunotherapy via meticulous checkpoint blockades. When appropriately stimulated, macrophages can morph into a potent bidirectional component of the immune system, engulfing malignant cells and annihilating them with cytotoxic substances, thus rendering them intriguing candidates for therapeutic targets. As myelomonocytic cells relentlessly amass within tumor tissues, macrophages rise as prime contenders for cell therapy upon the development of chimeric antigen receptor effector cells. Given the significant incidence of macrophage infiltration correlated with an unfavorable prognosis and heightened resistance to chemotherapy in solid tumors, we delve into the intricate role of macrophages in cancer propagation and their promising potential in confronting four formidable cancer variants-namely, melanoma, colon, glioma, and breast cancers.

Retinal determination gene networks: from biological functions to therapeutic strategies

The retinal determinant gene network (RDGN), originally discovered as a critical determinator in Drosophila eye specification, has become an important regulatory network in tumorigenesis and progression, as well as organogenesis. This network is not only associated with malignant biological behaviors of tumors, such as proliferation, and invasion, but also regulates the development of multiple mammalian organs. Three members of this conservative network have been extensively investigated, including DACH, SIX, and EYA. Dysregulated RDGN signaling is associated with the initiation and progression of tumors. In recent years, it has been found that the members of this network can be used as prognostic markers for cancer patients. Moreover, they are considered to be potential therapeutic targets for cancer. Here, we summarize the research progress of RDGN members from biological functions to signaling transduction, especially emphasizing their effects on tumors. Additionally, we discuss the roles of RDGN members in the development of organs and tissue as well as their correlations with the pathogenesis of chronic kidney disease and coronary heart disease. By summarizing the roles of RDGN members in human diseases, we hope to promote future investigations into RDGN and provide potential therapeutic strategies for patients.

The SIX1/LDHA Axis Promotes Lactate Accumulation and Leads to NK Cell Dysfunction in Pancreatic Cancer

Background

Pancreatic cancer (PC) is a malignant cancer with poor prognosis and high mortality rate. Sine oculis homeobox homolog 1 (SIX1) participates in the development of many cancers. However, the function of SIX1 in PC is not fully understood.

Methods

SIX1 expression was determined using immunohistochemistry in PC tissues and cell lines. Glucose consumption, lactate production, and ATP assays were used to detect the function of SIX1. PC cells and NK cells were cocultured to study the effect of SIX1 overexpression in PC cells on NK cell function. Chromatin immunoprecipitation (ChIP) assays were used to study the relationship between SIX1 and lactate dehydrogenase A (LDHA). A series of in vitro and in vivo assays were further applied to elucidate the important role of the SIX1/LDHA axis in metabolism and NK cell dysfunction in PC.

Results

SIX1 was significantly upregulated in PC tissue; SIX1 overexpression promoted the glycolysis capacity of PANC-1 and CFPAC-1 cells and resulted in NK cell dysfunction after the NK cells had been cultured with PC cells. LDHA inhibitor partially restored the promotion of PC caused by SIX1 overexpression. According to ChIP assays, SIX1 directly binds to the LDHA promoter region. Moreover, LDHA inhibitor and lactate transporter blocker treatment promoted the function of NK cells cocultured with PC cells. In vivo experiments yielded the same results.

Conclusion

The SIX1/LDHA axis promotes lactate accumulation and leads to NK cell dysfunction in PC.

Macrophage phenotype-switching in cancer

Tumour-associated macrophages (TAMs) have been found to be of great importance in tumorigenesis and in promoting malignant progression, including tumour angiogenesis and metastasis. Moreover, the TAM phenotype is more likely to be an M2 type. Transforming TAMs by M2-polarization into the tumour-suppressive M1-phenotype is an important approach for tumour therapy. In this review, we analysed the effects of the tumour microenvironment on macrophage phenotype-switching, including hypoxia and cytokines, and the mechanisms of drugs targeting TAMs. Furthermore, we analysed the effects of exosomes on macrophage polarization, phenotype switching of macrophages, and the mechanisms of lipid mediators targeting TAMs.

Sanguinarine Inhibition of TNF-α-Induced CCL2, IKBKE/NF-κB/ERK1/2 Signaling Pathway, and Cell Migration in Human Triple-Negative Breast Cancer Cells

Angiogenesis is a process that drives breast cancer (BC) progression and metastasis, which is linked to the altered inflammatory process, particularly in triple-negative breast cancer (TNBC). In targeting inflammatory angiogenesis, natural compounds are a promising option for managing BC. Thus, this study was designed to determine the natural alkaloid sanguinarine (SANG) potential for its antiangiogenic and antimetastatic properties in triple-negative breast cancer (TNBC) cells. The cytotoxic effect of SANG was examined in MDA-MB-231 and MDA-MB-468 cell models at a low molecular level. In this study, SANG remarkably inhibited the inflammatory mediator chemokine CCL2 in MDA-MB-231 and MDA-MB-468 cells. Furthermore, qRT-PCR confirmed with Western analysis studies showed that mRNA CCL2 repression was concurrent with reducing its main regulator IKBKE and NF-κB signaling pathway proteins in both TNBC cell lines. The total ERK1/2 protein was inhibited in the more responsive MDA-MB-231 cells. SANG exhibited a higher potential to inhibit cell migration in MDA-MB-231 cells compared to MDA-MB-468 cells. Data obtained in this study suggest a unique antiangiogenic and antimetastatic effect of SANG in the MDA-MB-231 cell model. These effects are related to the compound’s ability to inhibit the angiogenic CCL2 and impact the ERK1/2 pathway. Therefore, SANG use may be recommended as a component of the therapeutic strategy for TNBC.

Chemokines in progression, chemoresistance, diagnosis, and prognosis of colorectal cancer

Plenty of factors affect the oncogenesis and progression of colorectal cancer in the tumor microenvironment, including various immune cells, stromal cells, cytokines, and other factors. Chemokine is a member of the cytokine superfamily. It is an indispensable component in the tumor microenvironment. Chemokines play an antitumor or pro-tumor role by recruitment or polarization of recruiting immune cells. Meanwhile, chemokines, as signal molecules, participate in the formation of a cross talk among signaling pathways and non-coding RNAs, which may be involved in promoting tumor progression. In addition, they also function in immune escape. Chemokines are related to drug resistance of tumor cells and may even provide reference for the diagnosis, therapy, and prognosis of patients with colorectal cancer.

Macrophages Are a Double-Edged Sword: Molecular Crosstalk between Tumor-Associated Macrophages and Cancer Stem Cells

Cancer stem cells (CSCs) are a subset of highly tumorigenic cells in tumors. They have enhanced self-renewal properties, are usually chemo-radioresistant, and can promote tumor recurrence and metastasis. They can recruit macrophages into the tumor microenvironment and differentiate them into tumor-associated macrophages (TAMs). TAMs maintain CSC stemness and construct niches that are favorable for CSC survival. However, how CSCs and TAMs interact is not completely understood. An understanding on these mechanisms can provide additional targeting strategies for eliminating CSCs. In this review, we comprehensively summarize the reported mechanisms of crosstalk between CSCs and TAMs and update the related signaling pathways involved in tumor progression. In addition, we discuss potential therapies targeting CSC–TAM interaction, including targeting macrophage recruitment and polarization by CSCs and inhibiting the TAM-induced promotion of CSC stemness. This review also provides the perspective on the major challenge for developing potential therapeutic strategies to overcome CSC-TAM crosstalk.

Functional and Therapeutic Significance of Tumor-Associated Macrophages in Colorectal Cancer

The role of the tumor microenvironment (TME) in the progression of colorectal cancer (CRC) and its acquisition of resistance to treatment become the research hotspots. As an important component of TME, the tumor-associated macrophages (TAMs) regulate multiple critical oncogenic processes, namely, occurrence, proliferation, metastasis, and drug resistance in CRC. In this review, we have discussed the functional and therapeutic significance of TAMs in CRC. M1 macrophages act as the tumor suppressor while M2 macrophages promote CRC. The polarization of TAMs is mainly regulated by the pathways such as NFKB1 pathways, STAT3 pathways, WNT5A pathways, and PI3K pathways in CRC. Furthermore, the M2 polarization of TAMs is not only controllable but also reversible. Finally, we provide insights into the TAMs-targeted therapeutic strategies.

SIX1 transcription factor: A review of cellular functions and regulatory dynamics

Sine Oculis Homeobox 1 (SIX1) is a member of homeobox transcription factor family having pivotal roles in organismal development and differentiation. This protein functionally acts to regulate the expression of different proteins that are involved in organ development during embryogenesis and in disorders like cancer. Aberrant expression of this homeoprotein has therefore been reported in multiple pathological complexities like hearing impairment and renal anomalies during development and tumorigenesis in adult life. Most of the cellular effects mediated by it are mostly due to its role as a transcription factor. This review presents a concise narrative of its structure, interaction partners and cellular functions vis a vis its role in cancer. We thoroughly discuss the reported molecular mechanisms that govern its function in cellular milieu. Its post-translational regulation by phosphorylation and ubiquitination are also discussed with an emphasis on yet to be explored mechanistic insights regulating its molecular dynamics to fully comprehend its role in development and disease.

Homeoprotein SIX1 compromises antitumor immunity through TGF-β-mediated regulation of collagens

The tumor microenvironment (TME), including infiltrated immune cells, is known to play an important role in tumor growth; however, the mechanisms underlying tumor immunogenicity have not been fully elucidated. Here, we discovered an unexpected role for the transcription factor SIX1 in regulating the tumor immune microenvironment. Based on analyses of patient datasets, we found that SIX1 was upregulated in human tumor tissues and that its expression levels were negatively correlated with immune cell infiltration in the TME and the overall survival rates of cancer patients. Deletion of Six1 in cancer cells significantly reduced tumor growth in an immune-dependent manner with enhanced antitumor immunity in the TME. Mechanistically, SIX1 was required for the expression of multiple collagen genes via the TGFBR2-dependent Smad2/3 activation pathway, and collagen deposition in the TME hampered immune cell infiltration and activation. Thus, our study uncovers a crucial role for SIX1 in modulating tumor immunogenicity and provides proof-of-concept evidence for targeting SIX1 in cancer immunotherapy.

Circular RNA: A promising new star for the diagnosis and treatment of colorectal cancer

Background

Colorectal cancer (CRC) is one of the most common malignant tumors of the digestive tract. According to the research of circular RNAs in the CRC field, compared with linear RNAs, circular RNAs are a special type of noncoding RNA that are covalently closed circular structures, which have no 5' cap structure and 3' polyA tail and are not affected by RNA exonuclease and actinomycin D.

Biological functions

Notably, circular RNAs have a high degree of stability and potential effect on gene regulation. Meanwhile, circular RNAs are involved in the sponge action of microRNAs and mediate protein translation and direct binding, alternative splicing, and histone modification.

Relationships with CRC

Studies have shown that circular RNAs are related to the proliferation, invasion, recurrence, metastasis, ferroptosis, apoptosis, and chemotherapy resistance of CRC.

Conclusions

This article provides a brief review based on the source, structural characteristics, mechanisms, biological functions of circular RNAs, and the relationships between CRC.

ITLN1 inhibits tumor neovascularization and myeloid derived suppressor cells accumulation in colorectal carcinoma

Low levels of ITLN1 have been correlated with obesity-related colorectal carcinogenesis, however, the specific functions and underlying mechanisms remain unclear. Thus, we sought to explore the inhibitory role of ITLN1 in the tumor-permissive microenvironment that exists during the first occurrence and subsequent development of colorectal carcinoma (CRC). Results indicated that ITLN1 was frequently lost in CRC tissues and ITLN1 to be an independent prognostic predictor of CRC. Orthotopic and subcutaneous tumor xenograft approaches were then used to further confirm the protective role of ITLN1 during tumor progression. Increased ITLN1 expression in CRC cells significantly inhibited local pre-existing vessels sprouting, EPC recruitment and the infiltration of immunosuppressive myeloid-derived suppressor cells (MDSCs) into tumor tissues without affecting the behavior of CRC cells in vitro. Comparatively, ITLN1-derived MDSCs had a lower suppressive effect on T cell proliferation, NOS2 expression, and ROS production. In addition, ITLN1 overexpression markedly suppressed bone marrow (BM)-derived hematopoietic progenitor cells (HPC) differentiation into MDSCs as well as NOS2 activity on MDSCs. Using H-2b+YFP + chimerism through bone marrow transplantation, increased ITLN1 in HCT116 significantly reduced the BM-derived EPCs and MDSCs in vivo mobilization. Mechanistically, results indicated ITLN1 inhibited tumor-derived IL-17D and CXCL2 (MIP2) through the KEAP1/Nrf2/ROS/IL-17D and p65 NF-ĸB/CXCL2 signaling cascades dependent on PI3K/AKT/GSK3ß. This effect was reversed by the PI3K selective inhibitor LY294002. Collectively, ITLN1 synergistically suppressed IL-17D and CXCL2-mediated tumor vascularization, bone marrow derived EPC recruitment, as well as MDSCs generation and trafficking. Thus, ITLN1 potentially serves as a critical prognostic and therapeutic target for CRC.

Two naturally derived small molecules disrupt the sineoculis homeobox homolog 1-eyes absent homolog 1 (SIX1-EYA1) interaction to inhibit colorectal cancer cell growth

BACKGROUND

Emerging evidence indicates that the sineoculis homeobox homolog 1-eyes absent homolog 1 (SIX1-EYA1) transcriptional complex significantly contributes to the pathogenesis of multiple cancers by mediating the expression of genes involved in different biological processes, such as cell-cycle progression and metastasis. However, the roles of the SIX1-EYA1 transcriptional complex and its targets in colorectal cancer (CRC) are still being investigated. This study aimed to investigate the roles of SIX1-EYA1 in the pathogenesis of CRC, to screen inhibitors disrupting the SIX1-EYA1 interaction and to evaluate the efficiency of small molecules in the inhibition of CRC cell growth.

METHODS

Real-time quantitative polymerase chain reaction and western blotting were performed to examine gene and protein levels in CRC cells and clinical tissues (collected from CRC patients who underwent surgery in the Department of Integrated Traditional and Western Medicine, West China Hospital of Sichuan University, between 2016 and 2018, n = 24). In vivo immunoprecipitation and in vitro pulldown assays were carried out to determine SIX1-EYA1 interaction. Cell proliferation, cell survival, and cell invasion were determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, clonogenic assay, and Boyden chamber assay, respectively. The Amplified Luminescent Proximity Homogeneous Assay Screen (AlphaScreen) method was used to obtain small molecules that specifically disrupted SIX1-EYA1 interaction. CRC cells harboring different levels of SIX1/EYA1 were injected into nude mice to establish tumor xenografts, and small molecules were also injected into mice to evaluate their efficiency to inhibit tumor growth.

RESULTS

Both SIX1 and EYA1 were overexpressed in CRC cancerous tissues (for SIX1, 7.47 ± 3.54 vs.1.88 ± 0.35, t = 4.92, P = 0.008; for EYA1, 7.61 ± 2.03 vs. 2.22 ± 0.45, t = 6.73, P = 0.005). The SIX1/EYA1 complex could mediate the expression of two important genes including cyclin A1 (CCNA1) and transforming growth factor beta 1 (TGFB1) by binding to the myocyte enhancer factor 3 consensus. Knockdown of both SIX1 and EYA1 could decrease cell proliferation, cell invasion, tumor growth, and in vivo tumor growth (all P < 0.01). Two small molecules, NSC0191 and NSC0933, were obtained using AlphaScreen and they could significantly inhibit the SIX1-EYA1 interaction with a half-maximal inhibitory concentration (IC50) of 12.60 ± 1.15 μmol/L and 83.43 ± 7.24 μmol/L, respectively. Administration of these two compounds could significantly repress the expression of CCNA1 and TGFB1 and inhibit the growth of CRC cells in vitro and in vivo.

CONCLUSIONS

Overexpression of the SIX1/EYA1 complex transactivated the expression of CCNA1 and TGFB1, causing the pathogenesis of CRC. Pharmacological inhibition of the SIX1-EYA1 interaction with NSC0191 and NSC0933 significantly inhibited CRC cell growth by affecting cell-cycle progression and metastasis.

Tumor-Associated Macrophages (TAMs) in Colorectal Cancer (CRC): From Mechanism to Therapy and Prognosis

Colorectal cancer (CRC) is a malignant tumor in the digestive system whose incidence and mortality is high-ranking among tumors worldwide. The initiation and progression of CRC is a complex process involving genetic alterations in cancer cells and multiple factors from the surrounding tumor cell microenvironment. As accumulating evidence has shown, tumor-associated macrophages (TAMs)—as abundant and active infiltrated inflammatory cells in the tumor microenvironment (TME)—play a crucial role in CRC. This review focuses on the different mechanisms of TAM in CRC, including switching of phenotypical subtypes; promoting tumor proliferation, invasion, and migration; facilitating angiogenesis; mediating immunosuppression; regulating metabolism; and interacting with the microbiota. Although controversy remains in clinical evidence regarding the role of TAMs in CRC, clarifying their significance in therapy and the prognosis of CRC may shed new light on the optimization of TAM-centered approaches in clinical care.

Micro-positron emission tomography imaging of angiogenesis based on 18F-RGD for assessing liver metastasis of colorectal cancer

BACKGROUND

Positron emission tomography (PET) imaging is a non-invasive method to visualize and quantify the tumor microenvironment. This study aimed to explore the feasibility of ¹⁸F-AIF-NOTA-E[PEG₄-c(RGDfk)]₂ (denoted as ¹⁸F-RGD) PET quantitative parameters to distinguish the angiogenesis in colorectal cancer (CRC) mice which has different metastatic potential.

METHODS

Twenty LoVo and twenty LS174T of CRC liver metastases animal models were established by implantation of human CRC cell lines via intrasplenic injection. Radiotracer-based micro-PET imaging of animal model was performed and the uptake of ¹⁸F-RGD tracer in the tumor tissues was quantified as tumor-to-liver maximum or mean standardized uptake value (SUVmax or SUVmean) ratio. Pearson correlation was used to analyze the relationship between radioactive parameters and tumor markers.

RESULTS

The SUVmax and SUVmean ratios of LoVo model were significantly higher than those of LS174T in both liver metastasis and primary tumor lesions (P < 0.05). A significant difference was observed in both vascular endothelial growth factor (VEGF) and Ki67 expressions between LoVo and LS174T primary tumors (P < 0.05). The tumor-to-liver SUVmax or SUVmean ratio of ¹⁸F-RGD showed a moderate correlation with VEGF expression (r = 0.5700, P = 0.001 and r = 0.6657, P < 0.001, respectively), but the SUVmean ration showed a weak correlation with Ki67 expression (r = 0.3706, P < 0.05). The areas under the receiver operating characteristic (ROC) curves of ¹⁸F-RGD SUVmean ratio, SUVmax ratio for differentiating LoVo from LS174T tumor were 0.801 and 0.759, respectively.

CONCLUSIONS

The tumor-to-liver SUVmean ratio of ¹⁸F-RGD was a promising image parameter for the process of monitoring tumor angiogenesis in CRC xenograft mice model.

Macrophages, as a Promising Strategy to Targeted Treatment for Colorectal Cancer Metastasis in Tumor Immune Microenvironment

The tumor immune microenvironment plays a vital role in the metastasis of colorectal cancer. As one of the most important immune cells, macrophages act as phagocytes, patrol the surroundings of tissues, and remove invading pathogens and cell debris to maintain tissue homeostasis. Significantly, macrophages have a characteristic of high plasticity and can be classified into different subtypes according to the different functions, which can undergo reciprocal phenotypic switching induced by different types of molecules and signaling pathways. Macrophages regulate the development and metastatic potential of colorectal cancer by changing the tumor immune microenvironment. In tumor tissues, the tumor-associated macrophages usually play a tumor-promoting role in the tumor immune microenvironment, and they are also associated with poor prognosis. This paper reviews the mechanisms and stimulating factors of macrophages in the process of colorectal cancer metastasis and intends to indicate that targeting macrophages may be a promising strategy in colorectal cancer treatment.

High expression of SIX1 is an independent predictor of poor prognosis in endometrial cancer

Objective: The overexpression of transcription factor Sine oculis homeobox 1 (SIX1) is discovered in various malignant tumors and has been known to be closely associated with tumorigenesis, progression and prognosis. This study aims to determine the role of SIX1 in endometrial cancer (EC). Methods: In this study, we analyzed the SIX1 expression profile and the correlation with the corresponding clinical characteristics of EC samples from the Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO) and Clinical Proteomic Tumor Analysis Consortium (CPTAC) databases. Wilcoxon signed-rank test was applied to analyze the difference between tumor group and control group. The potential biological processes or signaling pathways related to SIX1 activity in EC was also assessed. Results: The results showed that SIX1 was overexpressed in EC tissues compared to normal tissues (P=2.029e-15, P=6.25e-6). The SIX1 level was correlated with tumor grade (P=2.91e-4), peritoneal cytology (P=0.005), and the subsequent tumor surgery (P=1.169e-4). SIX1 expression was negatively associated with overall survival rate (P=4.241e-4, P=0.000241) and served as an independent factor that affected EC overall survival rate (P=0.005063), similar to other factors such as age, Figo stage, and tumor (T) stage. SIX1 participates in cancer pathogenesis through gene regulation that involves PI3K/AKT/MTOR signaling, mitotic spindle, G2M checkpoint, E2F targets, NOTCH signaling, glycolysis, cholesterol homeostasis, DNA repair and early estrogen response. Conclusions: Our data demonstrate that SIX1 is overexpressed in EC and associated with adverse clinicopathological outcomes, which can function as an independent factor for EC prognosis.

Silencing SIX1 by miR-7160 inhibits non-small cell lung cancer cell growth

The homeoprotein SIX1 is upregulated in non-small cell lung cancer (NSCLC) and associated with NSCLC tumorigenesis and progression. We identified microRNA-7160 (miR-7160) as a SIX1-targeting miRNA. RNA immunoprecipitation results confirmed a direct binding between miR-7160 and SIX1 mRNA in NSCLC cells. In the primary and established NSCLC cells, forced overexpression of miR-7160 downregulated SIX1 and inhibited cancer cell growth, proliferation, migration and invasion. Furthermore, miR-7160 overexpression induced apoptosis activation in NSCLC cells. Conversely, miR-7160 inhibition elevated SIX1 expression and enhanced NSCLC cell progression in vitro. Restoring SIX1 expression, by an untranslated region-depleted SIX1 expression construct, reversed miR-7160-induced anti-NSCLC cell activity. CRISPR/Cas9-inudced knockout of SIX1 mimicked miR-7160-induced actions and produced anti-NSCLC cell activity. In vivo, intratumoral injection of miR-7160-expressing lentivirus downregulated SIX1 mRNA and inhibited NSCLC xenograft growth in severe combined immunodeficient mice. Significantly, miR-7160 expression is downregulated in human NSCLC tissues and is correlated with SIX1 mRNA upregulation. Collectively, miR-7160 silenced SIX1 and inhibited NSCLC cell growth in vitro and in vivo.

Severe acute respiratory syndrome coronavirus 2 may exploit human transcription factors involved in retinoic acid and interferon-mediated response: a hypothesis supported by an in silico analysis

The pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19), resulting in acute respiratory disease, is a worldwide emergency. Because recently it has been found that SARS-CoV is dependent on host transcription factors (TF) to express the viral genes, efforts are required to understand the molecular interplay between virus and host response. By bioinformatic analysis, we investigated human TF that can bind the SARS-CoV-2 sequence and can be involved in viral transcription. In particular, we analysed the key role of TF involved in interferon (IFN) response. We found that several TF could be induced by the IFN antiviral response, specifically some induced by IFN-stimulated gene factor 3 (ISGF3) and by unphosphorylated ISGF3, which were found to promote the transcription of several viral open reading frame. Moreover, we found 22 TF binding sites present only in the sequence of virus infecting humans but not bat coronavirus RaTG13. The 22 TF are involved in IFN, retinoic acid signalling and regulation of transcription by RNA polymerase II, thus facilitating its own replication cycle. This mechanism, by competition, may steal the human TF involved in these processes, explaining SARS-CoV-2's disruption of IFN-I signalling in host cells and the mechanism of the SARS retinoic acid depletion syndrome leading to the cytokine storm. We identified three TF binding sites present exclusively in the Brazilian SARS-CoV-2 P.1 variant that may explain the higher severity of the respiratory syndrome. These data shed light on SARS-CoV-2 dependence from the host transcription machinery associated with IFN response and strengthen our knowledge of the virus's transcription and replicative activity, thus paving the way for new targets for drug design and therapeutic approaches.

Six1 Promotes Epithelial-Mesenchymal Transition in Bronchial Epithelial Cells via the TGFβ1/Smad Signalling Pathway

INTRODUCTION

The homeodomain transcription factor sine oculis homeobox homolog 1 (Six1) plays a crucial role in embryogenesis and is not expressed in normal adult tissue but is expressed in many pathological processes, including airway remodelling in asthma. The current study aimed to reveal the effects of Six1 in regulating the airway remodelling and its possible mechanism.

METHODS

A mouse model of ovalbumin-induced asthma-associated airway wall remodelling and a bronchial epithelial cell (16HBE) model of transforming growth factor β1 (TGFβ1)-induced epithelial-mesenchymal transition (EMT) were used to investigate the role of Six1. Then, 16HBE cells were transformed with Six1 expression vectors and treated with a TGFβ1 pathway inhibitor to determine the role of Six1 in EMT. The effect of Six1 and its possible mechanism were assessed by immunohistochemistry, RT-PCR, and Western blot.

RESULTS

Six1 expression was elevated in the lungs in an OVA mouse model of allergic asthma and in 16HBE cells treated with TGFβ1. Six1 overexpression promoted an EMT-like phenotype with a decreased protein expression of E-cadherin and increased protein expression of α-smooth muscle actin (α-SMA) as well as fibronectin in 16HBE cells; these effects appeared to promote TGFβ1 and phospho-Smad2 (pSmad2) production, which are the main products of the TGFβ1/Smad signalling pathway, which could be reduced by a TGFβ1 inhibitor.

CONCLUSION

These data reveal that Six1 and TGFβ1 are potentially a part of an autocrine feedback loop that induces EMT, and these factors can be reduced by blocking the TGFβ1/Smad signalling pathway. As such, these factors may represent a promising novel therapeutic target for airway remodelling in asthma.

SPOCK1/SIX1axis promotes breast cancer progression by activating AKT/mTOR signaling

SPOCK1 is highly expressed in many types of cancer and has been recognized as a promoter of cancer progression. Its regulatory mechanism in breast cancer (BC) remains unclear. This study aimed to explore the precise function of SPOCK1 in BC progression and to identify the mechanism by which SPOCK1 is involved in cell proliferation and epithelial-mesenchymal transition (EMT). Immunohistochemistry (IHC) experiments and database analysis showed that high expression of SPOCK1 was positively associated with histological grade, lymph node metastasis (LN) and poor clinical prognosis in BC. A series of in vitro and in vivo assays elucidated that altering the SPOCK1 level led to distinct changes in BC cell proliferation and metastasis. Investigations of potential mechanisms revealed that SPOCK1 interacted with SIX1 to enhance cell proliferation, cell cycle progression and EMT by activating the AKT/mTOR pathway, whereas inhibition of the AKT/mTOR pathway or depletion of SIX1 reversed the effects of SPOCK1 overexpression. Furthermore, SPOCK1 and SIX1 were highly expressed in BC and might indicate poor prognoses. Altogether, the SPOCK1/SIX1 axis promoted BC progression by activating the AKT/mTOR pathway to accelerate cell proliferation and promote metastasis in BC, so the SPOCK1/SIX1 axis might be a promising clinical therapeutic target for preventing BC progression.

Macrophages in Giemsa-stained cerebrospinal fluid specimens predict carcinomatous meningitis

Carcinomatous meningitis is a condition in which tumor cells spread to the subarachnoid space. Leukocyte counting and typing of cerebrospinal fluid (CSF) cell components are performed manually or using flow cytometry. However, a detailed analysis of these variables using cytological specimens has not yet been reported. The present study analyzed cytological specimens using Giemsa staining and whole slide imaging with computer-assisted image analysis (CAIA) to clarify the characteristics of the leukocyte population in CSF, especially in carcinomatous meningitis. Manual evaluation was performed using 280 Giemsa-stained cytological CSF specimens. For 49 samples, CAIA was used for the whole area of Papanicolaou (Pap) staining, and Giemsa-stained specimens of the same samples were imaged using a virtual slide scanner. The nuclear morphology of the leukocytes was assessed, and the total leukocyte and leukocyte subset (lymphocytes, neutrophils and macrophages) counts were evaluated. Then, the number and percentage of each leukocyte subset population were evaluated. The total leukocyte count was significantly higher in Giemsa-stained specimens compared with in Pap-stained specimens. The percentage of macrophages was significantly higher in samples from patients with non-hematological tumors compared with in samples from patients without tumors, which was confirmed by manual evaluation of the specimens. In addition, the cut-off value of the percentage of macrophages that could discriminate between the tumor history negative cases and cytologically tumor positive cases was determined, revealing that a higher proportion of macrophages reflected the existence of atypical/malignant epithelial tumor cells in CSF samples. Thus, atypical cell screening and analysis of the background characteristics of the leukocyte population should be the focus of cytological specimen screening, especially not to miss carcinomatous meningitis.

SETDB1 promotes glioblastoma growth via CSF-1-dependent macrophage recruitment by activating the AKT/mTOR signaling pathway

Background

Glioblastoma is a common disease of the central nervous system (CNS), with high morbidity and mortality. In the infiltrate in the tumor microenvironment, tumor-associated macrophages (TAMs) are abundant, which are important factors in glioblastoma progression. However, the exact details of TAMs in glioblastoma progression have yet to be determined.

Methods

The clinical relevance of SET domain bifurcated 1 (SETDB1) was analyzed by immunohistochemistry, real-time PCR and Western blotting of glioblastoma tissues. SETDB1-induced cell proliferation, migration and invasion were investigated by CCK-8 assay, colony formation assay, wound healing and Transwell assay. The relationship between SETDB1 and colony stimulating factor 1 (CSF-1), as well as TAMs recruitment was examined by Western blotting, real-time PCR and syngeneic mouse model.

Results

Our findings showed that SETDB1 upregulated in glioblastoma and relative to poor progression. Gain and loss of function approaches showed the SETDB1 overexpression promotes cell proliferation, migration and invasion in glioblastoma cells. However, knockdown SETDB1 exerted opposite effects in vitro. Moreover, SETDB1 promotes AKT/mTOR-dependent CSF-1 induction and secretion, which leads to macrophage recruitment in the tumor, resulted in tumor growth.

Conclusion

Our research clarified that SETDB1 regulates of tumor microenvironment and hence presents a potential therapeutic target for treating glioblastoma.

VEGFR2 Promotes Metastasis and PD-L2 Expression of Human Osteosarcoma Cells by Activating the STAT3 and RhoA-ROCK-LIMK2 Pathways

The survival rate of osteosarcoma, the most prevalent primary bone tumor, has not been effectively improved in the last 30 years. Hence, new treatments and drugs are urgently needed. Antiangiogenic therapy and immunotherapy have good antitumor effects in many kinds of tumors. It is hypothesized that there may be a synergistic effect between immune checkpoint inhibitors and antiangiogenic therapy. Nevertheless, its potential mechanism is still unclear. Vascular endothelial growth factor receptor-2 (VEGFR2) expression was detected by immunohistochemistry in 18 paired osteosarcoma tissues. Moreover, we investigated the effects of apatinib treatment and VEGFR2 knockdown on osteosarcoma as well as the relevant underlying mechanism. Immunohistochemistry assays showed that, compared with that in primary osteosarcoma, VEGFR2 expression was higher in lung metastases. VEGFR2 was positively correlated with PD-L2 expression in osteosarcoma lung metastasis. Transwell assays indicated that VEGFR2 inhibition reduced osteosarcoma cell metastatic abilities in vitro. We also demonstrated that VEGFR2 inhibition downregulated the STAT3 and RhoA-ROCK-LIMK2 pathways, thereby attenuating migration and invasion. Additionally, VEGFR2 inhibition targeted STAT3, through which it reduced PD-L2 expression in osteosarcoma cells. VEGFR2 inhibition markedly attenuated osteosarcoma lung metastatic ability in vivo. In this study, we presented the pro-metastatic functional mechanism of VEGFR2 in osteosarcoma. VEGFR2 inhibition exhibits antitumor effects through antiangiogenic effects and inhibition of immune escape, which possibly provides potential clinical treatment for metastatic osteosarcoma.

OIP5-AS1 modulates epigenetic regulator HDAC7 to enhance non-small cell lung cancer metastasis via miR-140-5p

Long non-coding RNAs have been reported to be involved in non-small cell lung cancer (NSCLC) progression. However, whether Opa-interacting protein 5 antisense RNA 1 (OIP5-AS1) serves a role in NSCLC remains unclear. Bioinformatics analysis of The Cancer Genome Atlas datasets showed clinical significance and relevance of OIP5-AS1 in NSCLC. Western blotting and reverse transcription-quantitative PCR revealed protein and RNA expression levels of the genes [including OIP5-AS1, microRNA (miR)-140-5p, histone deacetylase 7 (HDAC7) and vascular endothelial growth factor A (VEGFA)]. Direct associations between the genes (miR-140-5p and OIP5-AS1, or miR-140-5p and HDAC7) were confirmed using a dual-luciferase reporter assay. Lymphatic vessel formation and invasion ability were detected using a lymphatic vessel formation assay and Transwell invasion assay. OIP5-AS1 knockdown attenuated lymphatic vessel length and invasion. The role of OIP5-AS1 was reverted by miR-140-5p. HDAC7 and VEGFA are downstream effectors of miR-140-5p-mediated NSCLC metastasis. OIP5-AS1, miR-140-5p, HDAC7 and VEGFA were all dysregulated in human clinical NSCLC tumor tissues. In conclusion, the present results demonstrated a novel mechanism for OIP5-AS1-induced metastatic phenotypes of NSCLC via the miR-140-5p/HDAC7/VEGFA axis.

Colon-specific immune microenvironment regulates cancer progression versus rejection

Immunotherapies have achieved clinical benefit in many types of cancer but remain limited to a subset of patients in colorectal cancer (CRC). Resistance to immunotherapy can be attributed in part to tissue-specific factors constraining antitumor immunity. Thus, a better understanding of how the colon microenvironment shapes the immune response to CRC is needed to identify mechanisms of resistance to immunotherapies and guide the development of novel therapeutics. In an orthotopic mouse model of MC38-CRC, tumor progression was monitored by bioluminescence imaging and the immune signatures were assessed at a transcriptional level using NanoString and at a cellular level by flow cytometry. Despite initial tumor growth in all mice, only 25% to 35% of mice developed a progressive lethal CRC while the remaining animals spontaneously rejected their solid tumor. No tumor rejection was observed in the absence of adaptive immunity, nor when MC38 cells were injected in non-orthotopic locations, subcutaneously or into the liver. We observed that progressive CRC tumors exhibited a protumor immune response, characterized by a regulatory T-lymphocyte pattern, discernible shortly post-tumor implantation, as well as suppressive myeloid cells. In contrast, tumor-rejecting mice presented an early inflammatory response and an antitumor microenvironment enriched in CD8⁺ T cells. Taken together, our data demonstrate the role of the colon microenvironment in regulating the balance between anti or protumor immune responses. While emphasizing the relevance of the CRC orthotopic model, they set the basis for exploring the impact of the identified signatures in colon cancer response to immunotherapy.

<p>In vivo Screening of Natural Products Against Angiogenesis and Mechanisms of Anti-Angiogenic Activity of Deoxysappanone B 7,4ʹ-Dimethyl Ether</p>

Introduction

The aim of this study was to screen the leading compounds of natural origin with anti-angiogenic potential and to investigate their anti-angiogenic mechanism preliminarily.

Materials and Methods

An initial screening of 240 compounds from the Natural Products Collection of MicroSource was performed using the transgenic zebrafish strain Tg [fli1a: enhanced green fluorescent protein (EGFP)]^y1. The zebrafish embryos at 24 h post-fertilization were exposed to the natural compounds for an additional 24 h; then, morphological changes in the intersegmental vessels (ISVs) were observed and quantified under a fluorescence microscope. The expression profiles of angiogenesis-related genes in the zebrafish embryos were detected using quantitative real-time PCR.

Results

Five compounds were identified with potential anti-angiogenic activity on the zebrafish embryogenesis. Among them, deoxysappanone B 7.4ʹ-dimethyl ether (Deox B 7,4) showed anti-angiogenic activity on the formation of ISVs in a dose-dependent manner. The inhibition of ISV formation reached up to 99.64% at 5 μM Deox B 7,4. The expression of delta-like ligand 4 (dll4), hes-related family basic helix-loop-helix transcription factor with YRPW motif 2, ephrin B2, fibroblast growth factor receptor (fgfr) 3, cyclooxygenase-2, protein tyrosine phosphatase, receptor type B (ptp-rb), phosphoinositide-3-kinase regulatory subunit 2, slit guidance ligand (slit) 2, slit3, roundabout guidance receptor (robo) 1, robo2, and robo4 were down-regulated, while vascular endothelial growth factor receptor-2, fgfr 1, and matrix metallopeptidase 9 were up-regulated in the zebrafish embryos treated with Deox B 7,4.

Conclusion

Deox B 7,4 has a therapeutic potential for the treatment of angiogenesis-dependent diseases and may exert anti-angiogenic activities by suppressing the slit2/robo1/2, slit3/robo4, cox2/ptp-rb/pik3r2, and dll4/hey2/efnb2a signaling pathways as well as activation of vegfr-2/fgfr1/mmp9.

Identification of a Small-Molecule Inhibitor That Disrupts the SIX1/EYA2 Complex, EMT, and Metastasis

Metastasis is the major cause of mortality for patients with cancer, and dysregulation of developmental signaling pathways can significantly contribute to the metastatic process. The Sine oculis homeobox homolog 1 (SIX1)/eyes absent (EYA) transcriptional complex plays a critical role in the development of multiple organs and is typically downregulated after development is complete. In breast cancer, aberrant expression of SIX1 has been demonstrated to stimulate metastasis through activation of TGFβ signaling and subsequent induction of epithelial-mesenchymal transition (EMT). In addition, SIX1 can induce metastasis via non-cell autonomous means, including activation of GLI-signaling in neighboring tumor cells and activation of VEGFC-induced lymphangiogenesis. Thus, targeting SIX1 would be expected to inhibit metastasis while conferring limited side effects. However, transcription factors are notoriously difficult to target, and thus novel approaches to inhibit their action must be taken. Here we identified a novel small molecule compound, NCGC00378430 (abbreviated as 8430), that reduces the SIX1/EYA2 interaction. 8430 partially reversed transcriptional and metabolic profiles mediated by SIX1 overexpression and reversed SIX1-induced TGFβ signaling and EMT. 8430 was well tolerated when delivered to mice and significantly suppressed breast cancer-associated metastasis in vivo without significantly altering primary tumor growth. Thus, we have demonstrated for the first time that pharmacologic inhibition of the SIX1/EYA2 complex and associated phenotypes is sufficient to suppress breast cancer metastasis. SIGNIFICANCE: These findings identify and characterize a novel inhibitor of the SIX1/EYA2 complex that reverses EMT phenotypes suppressing breast cancer metastasis.

Angiogenesis-promoting factors in colorectal cancer

Colorectal cancer (CRC) is one of the common malignant tumors, accounting for about 10% and 9.4% of malignancies in males and females, respectively. The number of patients who die from CRC reaches 700000 each year. In addition, there are about 1.4 million new patients every year. Angiogenesis is involved in a variety of physiological and pathological processes and is an important pathological marker for many diseases such as tumor, ischemia, atherosclerosis, inflammation, wound healing, and tissue regeneration. Angiogenesis plays a crucial role in the occurrence, development, and metastasis of CRC. In this review, we summarize our current knowledge of tumor-associated angiogenesis, the factors that promote angiogenesis in CRC, and future directions in this field, with an aim to provide a theoretical basis for better understanding the role of angiogenesis in the pathogenesis of CRC.

Angiogenesis in Breast Cancer Progression, Diagnosis, and Treatment

Angiogenesis is a significant event in a wide range of healthy and diseased conditions. This process frequently involves vasodilation and an increase in vascular permeability. Numerous players referred to as angiogenic factors, work in tandem to facilitate the outgrowth of endothelial cells (EC) and the consequent vascularity. Conversely, angiogenic factors could also feature in pathological conditions. Angiogenesis is a critical factor in the development of tumors and metastases in numerous cancers. An increased level of angiogenesis is associated with decreased survival in breast cancer patients. Therefore, a good understanding of the angiogenic mechanism holds a promise of providing effective treatments for breast cancer progression, thereby enhancing patients' survival. Disrupting the initiation and progression of this process by targeting angiogenic factors such as vascular endothelial growth factor (Vegf)-one of the most potent member of the VEGF family- or by targeting transcription factors, such as Hypoxia-Inducible Factors (HIFs) that act as angiogenic regulators, have been considered potential treatment options for several types of cancers. The objective of this review is to highlight the mechanism of angiogenesis in diseases, specifically its role in the progression of malignancy in breast cancer, as well as to highlight the undergoing research in the development of angiogenesis-targeting therapies.

Formation of colorectal liver metastases induces musculoskeletal and metabolic abnormalities consistent with exacerbated cachexia

Advanced colorectal cancer (CRC) is often accompanied by development of liver metastases (LMs) and skeletal muscle wasting (i.e., cachexia). Despite plaguing the majority of CRC patients, cachexia remains unresolved. By using mice injected with Colon-26 mouse tumors, either subcutaneously (s.c.; C26) or intrasplenically to mimic hepatic dissemination of cancer cells (mC26), here we aimed to further characterize functional, molecular, and metabolic effects on skeletal muscle and examine whether LMs exacerbate CRC-induced cachexia. C26-derived LMs were associated with progressive loss of body weight, as well as with significant reductions in skeletal muscle size and strength, in line with reduced phosphorylation of markers of protein anabolism and enhanced protein catabolism. mC26 hosts showed prevalence of fibers with glycolytic metabolism and enhanced lipid accumulation, consistent with abnormalities of mitochondrial homeostasis and energy metabolism. In a comparison with mice bearing s.c. C26, cachexia appeared exacerbated in the mC26 hosts, as also supported by differentially expressed pathways within skeletal muscle. Overall, our model recapitulates the cachectic phenotype of metastatic CRC and reveals that formation of LMs resulting from CRC exacerbate cancer-induced skeletal muscle wasting by promoting differential gene expression signatures.

MicroRNA-155-3p promotes glioma progression and temozolomide resistance by targeting Six1

The prognosis of glioma is generally poor and is the cause of primary malignancy in the brain. The role of microRNAs has been implicated in tumour inhibition or activation. In several cancers, the Six1 signalling pathway has been found to be aberrant and also relates to the formation of tumours. We analysed the database for expression profiles and clinical specimens of various grades of glioma to assess microRNA-155-3p (miR-155-3p) expression. The role of miR-155-3p in glioblastoma, cell cycle, proliferation, apoptosis and resistance to temozolomide was assessed in vitro through flow cytometry and cell proliferation assays. Bioinformatics analyses, and assays using luciferase reporter, and immunoblotting revealed that miR-155-3p targets Six1 and that the relationship between glioma and healthy brain tissues was significantly inverse. In rescue experiments, overexpressed Six1 revoked the changes in cell cycle distribution, proliferation and resistance to temozolomide estimated by apoptosis induced by overexpressed miR-155-3p. MiR-155-3p inhibition reduced glioma cell growth and proliferation in the brain of a mouse model and increased the survival of mice with gliomas. Thus, miR-155-3p modulates Six1 expression and facilitates the progression of glioblastoma and resistance to temozolomide and may act as a novel diagnostic biomarker and a target for glioma treatment.

Mouse models of colorectal cancer: Past, present and future perspectives

Colorectal cancer (CRC) is the third most common diagnosed malignancy among both sexes in the United States as well as in the European Union. While the incidence and mortality rates in western, high developed countries are declining, reflecting the success of screening programs and improved treatment regimen, a rise of the overall global CRC burden can be observed due to lifestyle changes paralleling an increasing human development index. Despite a growing insight into the biology of CRC and many therapeutic improvements in the recent decades, preclinical in vivo models are still indispensable for the development of new treatment approaches. Since the development of carcinogen-induced rodent models for CRC more than 80 years ago, a plethora of animal models has been established to study colon cancer biology. Despite tenuous invasiveness and metastatic behavior, these models are useful for chemoprevention studies and to evaluate colitis-related carcinogenesis. Genetically engineered mouse models (GEMM) mirror the pathogenesis of sporadic as well as inherited CRC depending on the specific molecular pathways activated or inhibited. Although the vast majority of CRC GEMM lack invasiveness, metastasis and tumor heterogeneity, they still have proven useful for examination of the tumor microenvironment as well as systemic immune responses; thus, supporting development of new therapeutic avenues. Induction of metastatic disease by orthotopic injection of CRC cell lines is possible, but the so generated models lack genetic diversity and the number of suited cell lines is very limited. Patient-derived xenografts, in contrast, maintain the pathological and molecular characteristics of the individual patient's CRC after subcutaneous implantation into immunodeficient mice and are therefore most reliable for preclinical drug development - even in comparison to GEMM or cell line-based analyses. However, subcutaneous patient-derived xenograft models are less suitable for studying most aspects of the tumor microenvironment and anti-tumoral immune responses. The authors review the distinct mouse models of CRC with an emphasis on their clinical relevance and shed light on the latest developments in the field of preclinical CRC models.

HCT116 colorectal liver metastases exacerbate muscle wasting in a mouse model for the study of colorectal cancer cachexia

Colorectal cancer (CRC) is often accompanied by formation of liver metastases (LM) and skeletal muscle wasting, i.e. cachexia. Despite affecting the majority of CRC patients, cachexia remains underserved, understudied and uncured. Animal models for the study of CRC-induced cachexia, in particular models containing LM, are sparse; therefore, we aimed to characterize two new models of CRC cachexia. Male NSG mice were injected subcutaneously (HCT116) or intrasplenically (mHCT116) with human HCT116 CRC tumor cells to disseminate LM, whereas experimental controls received saline (n=5-8/group). Tumor growth was accompanied by loss of skeletal muscle mass (HCT116: -20%; mHCT116: -31%; quadriceps muscle) and strength (HCT116: -20%; mHCT116: -27%), with worsened loss of skeletal muscle mass in mHCT116 compared with HCT116 (gastrocnemius: -19%; tibialis anterior: -22%; quadriceps: -21%). Molecular analyses revealed elevated protein ubiquitination in HCT116, whereas mHCT116 also displayed elevated Murf1 and atrogin-1 expression, along with reduced mitochondrial proteins PGC1α, OPA1, mitofusin 2 and cytochrome C. Further, elevated IL6 levels were found in the blood of mHCT116 hosts, which was associated with higher phosphorylation of STAT3 in skeletal muscle. To clarify whether STAT3 was a main player in muscle wasting in this model, HCT116 cells were co-cultured with C2C12 myotubes. Marked myotube atrophy (-53%) was observed, along with elevated phospho-STAT3 levels (+149%). Conversely, inhibition of STAT3 signaling by means of a JAK/STAT3 inhibitor was sufficient to rescue myotube atrophy induced by HCT116 cells (+55%). Overall, our results indicate that the formation of LM exacerbates cachectic phenotype and associated skeletal muscle molecular alterations in HCT116 tumor hosts.

The Association Between Inflammation, Epithelial Mesenchymal Transition and Stemness in Colorectal Carcinoma

Background

Inflammation plays an important albeit dual role in carcinogenesis. Survival studies have highlighted the prognostic significance of peritumorous inflammation. Currently, the theoretical background allows inflammation, epithelial mesenchymal transition (EMT) and the closely associated stem cell differentiation in colorectal carcinoma (CRC) to be linked. However, there is scarce direct morphological evidence.

Purpose and methods

The aim of our study was to investigate the role of inflammation in cancer growth and invasion by analyzing the association between inflammation and known morphological prognostic features of colorectal cancer, EMT, stemness and mismatch repair (MMR) protein expression. The study was designed as a retrospective morphological and immunohistochemical assessment of 553 consecutive cases of surgically treated primary CRC.

Results

There were statistically significant associations between high-grade inflammation and lower pT (p = 0.002), absence of lymph node metastases (p < 0.001) and less frequent lymphatic (p = 0.003), venous (p = 0.017), arterial (p = 0.012), perineural (p = 0.001) and intraneural (p = 0.01) invasion. In contrast, Crohn's like reaction (CLR) by density of lymphoid follicles in the invasive front lacked significant differences in regard to pT, pN, tumor invasion into surrounding structures (blood or lymphatic vessels, nerves), grade or necrosis (all p > 0.05). The expression of E-cadherin, CD44 and MMR proteins yielded no statistically significant associations with peritumorous inflammation by Klintrup-Mäkinen score or the density of lymphoid follicles. Nevertheless, E-cadherin levels were significantly associated with the density of eosinophils (p = 0.007).

Conclusion

High-grade peritumorous inflammation is associated with beneficial morphologic CRC features, including less frequent manifestations of invasion, and is not secondary to tissue damage and necrosis. CLR is not associated with cancer spread by pTN; this finding indirectly suggests an independent role of CLR in carcinogenesis. Further, inflammation by Klintrup-Mäkinen grade and CLR is not dependent on epithelial-mesenchymal transition and stem cell differentiation. Our study highlights the complex associations between inflammation, tumor morphology, EMT, stemness and MMR protein expression in human CRC tissues.

Circular RNA circNHSL1 promotes gastric cancer progression through the miR-1306-3p/SIX1/vimentin axis

Background

Mounting evidences indicate that circular RNAs (circRNAs) play vital roles in the development and progression of various cancers. However, the detail functions and underlying mechanisms of circRNAs in gastric cancer remain largely unknown.

Methods

The expression profile of metastasis-related circRNAs was screened by RNA-seq analysis. qRT-PCR was used to determine the level and prognostic values of circNHSL1 in gastric cancer tissues. In vitro cell wound healing and transwell (migration and invasion) and in vivo tumorigenesis and metastasis assays were performed to evaluate the functions of circNHSL1. Luciferase reporter, RNA immunoprecipitation (RIP) and rescued assays were employed to confirm the interactions between circNHSL1, miR-1306-3p and SIX1. It’s widely accepted that as a mesenchymal marker, Vimentin promotes invasion and metastasis in various cancers. Luciferase reporter assay was used to determine the regulation of SIX1 on Vimentin. In addition, In situ hybridization (ISH) was performed to detect the level and prognostic values of miR-1306-3p.

Results

We found that the level of circNHSL1 was significantly up-regulated in gastric cancer, and positively correlated with clinicopathological features and poor prognosis of patients with gastric cancer. Functionally, circNHSL1 promoted cell mobility and invasion, as well as in vivo tumorgenesis and metastasis. Mechanistically, circNHSL1 acted as a miR-1306-3p sponge to relieve the repressive effect of miR-1306-3p on its target SIX1. Moreover, SIX1 enhanced Vimentin expression in the transcriptional level through directly binding to the promoter domain of Vimentin, thereby promoting cell migration and invasion. In addition, miR-1306-3p was down-regulated and negatively correlated with pathological features and poor prognosis in gastric cancer.

Conclusions

CircNHSL1 promotes gastric cancer progression through miR-1306-3p/SIX1/Vimentin axis, and may serve as a novel diagnostic marker and target for treatment of gastric cancer patients.

Electronic supplementary material

The online version of this article (10.1186/s12943-019-1054-7) contains supplementary material, which is available to authorized users.