Promote Tumor Malignancy Research Articles

PSAT1 Promotes Metastasis via p-AKT/SP1/ITGA2 Axis in Estrogen Receptor-Negative Breast Cancer Cell.

Accumulating evidence indicates that PSAT1 not only reprogrammed metabolic function but also exhibits "moonlighting" functions in promoting tumor malignancy. However, the underlying molecular mechanisms of PSAT1 promoting ER-negative breast cancer cell migration need further investigation. Briefly, the PSAT1 and ITGA2 expression in cells and tissues was detected using qRT-PCR, immunofluorescence staining and western blot assay. The effect of PSAT1 and ITGA2 was verified both in vitro and in vivo. RNA-seq analysis explored a series of differently expressed genes. The regulation between SP1 and ITGA2 was investigated by ChIP analysis. We reported PSAT1 was highly expressed in ER-breast cancer tissues and tumor cells and positively correlated with metastasis. Moreover, RNA-seq analysis explored a series of differently expressed genes, including ITGA2, in PSAT1 overexpressed cells. Mechanistically, PSAT1 facilitated breast cancer metastasis via the p-AKT/SP1/ITGA2 axis. We further elucidated that PSAT1 promoted the entry of SP1 into the nucleus through the upregulation of p-AKT and confirmed ITGA2 is a target of SP1. In addition, enhanced cell migration was remarkably reversed by ITGA2 depletion or p-AKT inhibitor treatment. This study clarified the mechanism of PSAT1 in promoting ER-negative breast cancer metastasis, which may provide mechanistic clues for attenuating breast cancer metastasis.

CCL2 mediated IKZF1 expression promotes M2 polarization of glioma-associated macrophages through CD84-SHP2 pathway.

The proneural-mesenchymal (PN-MES) transformation of glioma stem cells (GSCs) can significantly increase proliferation, invasion, chemotherapy tolerance, and recurrence. M2-like polarization of tumor-associated macrophages (TAMs) has a strong immunosuppressive effect, promoting tumor malignancy and angiogenesis. There is limited understanding on the interactions between GSCs and TAMs as well as their associated molecular mechanisms. In the present study, bioinformatics analysis, GSC and TAM co-culture, determination of TAM polarization phenotypes, and other in vitro experiments confirmed that CCL2 secreted by MES-GSCs promotes TAM-M2 polarization via the IKZF1-CD84-SHP2 pathway and PN-MES transformation of GSCs via the IKZF1-LRG1 pathway in TAMs. IKZF1 inhibitors could significantly reduce tumor volumes in animal glioma models and improve survival, as well as suppress TAM-M2 polarization and the GSC malignant phenotype. The results of this study indicate the important interaction between TAMs and GSCs in the glioma microenvironment as well as its role in tumor progression. The findings also suggest a novel target for follow-up clinical transformation research on the regulation of TAM function and GSCs malignant phenotype.

Tumor-derived miR-6794-5p enhances cancer growth by promoting M2 macrophage polarization

BackgroundSolid tumors promote tumor malignancy through interaction with the tumor microenvironment, resulting in difficulties in tumor treatment. Therefore, it is necessary to understand the communication between cells in the tumor and the surrounding microenvironment. Our previous study revealed the cancer malignancy mechanism of Bcl-w overexpressed in solid tumors, but no study was conducted on its relationship with immune cells in the tumor microenvironment. In this study, we sought to discover key factors in exosomes secreted from tumors overexpressing Bcl-w and analyze the interaction with the surrounding tumor microenvironment to identify the causes of tumor malignancy.MethodsTo analyze factors affecting the tumor microenvironment, a miRNA array was performed using exosomes derived from cancer cells overexpressing Bcl-w. The discovered miRNA, miR-6794-5p, was overexpressed and the tumorigenicity mechanism was confirmed using qRT-PCR, Western blot, invasion, wound healing, and sphere formation ability analysis. In addition, luciferase activity and Ago2-RNA immunoprecipitation assays were used to study the mechanism between miR-6794-5p and its target gene SOCS1. To confirm the interaction between macrophages and tumor-derived miR-6794-5p, co-culture was performed using conditioned media. Additionally, immunohistochemical (IHC) staining and flow cytometry were performed to analyze macrophages in the tumor tissues of experimental animals.ResultsMiR-6794-5p, which is highly expressed in exosomes secreted from Bcl-w-overexpressing cells, was selected, and it was shown that the overexpression of miR-6794-5p increased migratory ability, invasiveness, and stemness maintenance by suppressing the expression of the tumor suppressor SOCS1. Additionally, tumor-derived miR-6794-5p was delivered to THP-1-derived macrophages and induced M2 polarization by activating the JAK1/STAT3 pathway. Moreover, IL-10 secreted from M2 macrophages increased tumorigenicity by creating an immunosuppressive environment. The in vitro results were reconfirmed by confirming an increase in M2 macrophages and a decrease in M1 macrophages and CD8+ T cells when overexpressing miR-6794-5p in an animal model.ConclusionsIn this study, we identified changes in the tumor microenvironment caused by miR-6794-5p. Our study indicates that tumor-derived miR-6794-5p promotes tumor aggressiveness by inducing an immunosuppressive environment through interaction with macrophage.

Abstract 5397: Characteristics of cancer associated fibroblasts isolated from refractory colorectal cancer using RNA sequence

Abstract Primary tumor location of colorectal cancers (CRCs) is emerging as an important prognostic factor owing to distinct biological features. In fact, the patients with right-side CRCs (R-CRCs), in which primary tumors were resected in our department and followed by systemic chemotherapy, have a poorer prognosis in 2-year overall survival and progression-free survival than those with left-side CRCs (L-CRCs). Furthermore, cancer-associated fibroblasts (CAFs) promote tumor malignancy, but the precise transcriptional mechanisms regulating the acquisition of the CAF phenotype are not well understood. Here, we isolated the CAFs and normal counterparts from 10 CRCs which were performed radical resection, including 5 L-CRCs and 5 R-CRCs, and analyzed transcriptomic profile of CAFs by RNA-sequencing. Gene Set Enrichment Analysis (GSEA) was performed and inflammatory signatures, such as "HALLMARK IL2 STAT5 SIGNALING"(NOM p-value<0.001, FDR q-value=0.146), "HALLMARK IL6 JAK STAT3 SIGNALING"(NOM p-value=0.014, FDR q-value=0.162), "HALLMARK INTERFERON GAMMA RESPONSE"(NOM p-value=0.032, FDR q-value=0.1726), were enriched in the CAFs isolated from R-CRCs (R-CAFs). In addition to sidedness of CRCs, based on gene expression profiles from bulk tumors, CRCs were classified into four consensus molecular subtypes (CMS1-4). Among them, The fibrotic CMS4 subtype portends poor relapse-free survival. We identified 4 CMS4-CRCs, which have the characteristics of stromal activation and the worst prognosis among other CRCs. GSEA showed that the signature of "HALLMARK TNFA_SIGNALING_VIA_NFKB" (NOM p-value=0.023 FDR q-value=0.207), "HALLMARK GLYCOLYSIS" (NOM p-value=0.036 FDR q-value=0.239) were upregulated in the CAFs isolated from CMS4-CRCs. These results indicated that CAFs isolated from refractory CRCs have unique phenotypes and the elucidation of these mechanisms might lead to a promising treatment for refractory CRCs. Citation Format: Hiroaki Kasashima, Yasuhiro Fukui, Ken Yonemitsu, Kisyu Kitayama, Yuichiro Miki, Mami Yoshii, Tatsunari Fukuoka, Tatsuro Tamura, Masatsune Shibutani, Takahiro Toyokawa, Shigeru Ree, Masakazu Yashiro, Kiyoshi Maeda. Characteristics of cancer associated fibroblasts isolated from refractory colorectal cancer using RNA sequence [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5397.

GOLPH3 promotes tumor malignancy via inhibition of ferroptosis by upregulating SLC7A11 in cholangiocarcinoma.

Golgi phosphoprotein 3 (GOLPH3) has been reported as an oncogene in various tumors; however, the role and function of GOLPH3 and its relevant molecular mechanism in cholangiocarcinoma (CCA) are unclear. Herein, GOLPH3 expression in CCA tissues was observed to be significantly higher than that in paired adjacent noncancerous tissues. Clinicopathological analysis showed that GOLPH3 expression correlated positively with the tumor-node-metastasis stage. In addition, GOLPH3 expression correlated inversely with the overall survival of patients with CCA. Multivariate analysis showed that GOLPH3 was an independent prognostic factor for patients with CCA. Transcriptome analysis (RNA sequencing) of GOLPH3 knockdown cells showed that the expression levels of nine ferroptosis-related genes were significantly changed, indicating the important biological function of GOLPH3 in ferroptosis in CCA cells. Furthermore, GOLPH3 knockdown could significantly promote Erastin-induced ferroptosis in vitro and suppress tumor growth in vivo. Overexpression of GOLPH3 had the opposite effect on this phenotype. Further studies revealed that GOLPH3 knockdown was significantly associated with a decrease in cysteine content, an accumulation of the lipid peroxidation product malondialdehyde, an increase in reactive oxygen species, and sensitized CCA cells to Erastin-induced ferroptosis. Moreover, changes in GOLPH3 expression were found to be consistent with the expression of light chain subunit solute carrier family 7 member 11 (SLC7A11). Thus, our study suggested that GOLPH3 functions as an oncoprotein in CCA and may suppress ferroptosis by facilitating SLC7A11 expression, suggesting that GOLPH3 could serve as a therapeutic target for CCA treatment.

TMIC-06. GLIOBLASTOMA PROGRESSION IS PROMOTED BY C5AR1 SIGNALING THROUGH EMT INDUCTION, AND ITS BLOCKADE BY W54011 ATTENUATES MALIGNANT PHENOTYPES

Abstract BACKGROUND Glioblastoma multiforme (GBM) is an aggressive brain tumor with poor prognosis. Tumor mesenchymal stem-like cells (tMSLCs) in GBM tissues secrete complement component 5a (C5a), which promotes tumor malignancy. This study aimed to investigate the impact of C5a on GBM tumorspheres (GBM-TS) and to evaluate the therapeutic potential of C5a inhibition using the C5a antagonist, W54011. METHODS RNA sequencing (RNAseq) was performed on tumor tissues to identify differentiaaly expressing genes (DEG) and perform gene set enrichment analysia (GSEA) to correlate with patient survival based on C5aR1 expression. GBM-TS and tMSLCs were cultured to create a conditioned medium (CM) containing C5a, which was used to stimulate GBM-TS. The effect of C5a on GBM-TS proliferation, invasion, and stemness was determined using WST/ATP assay, 3D invasion assay, and neurosphere formation assay. Western blot and RNAseq analysis were performed to validate the results. In vivo studies were conducted using orthotopic xenograft mouse models injected with GBM-TS alone or with CM and treated with W54011. RESULTS Patients with high C5aR1 expression had a poor prognosis. Treatment with CM increased proliferation, invasion, and stemness of GBM-TS, but W54011 reversed these effects. Treatment with CM induced epithelial-messenchymal transition (EMT) in GBM TSs, whereas W54011 restored the spherical morphology and induced apoptosis. Our results were supported by transcriptome analysis and marker expression in Western blots. In the orthotopic xenograft mouse model, co-injection of GBM-TS and CM resulted in larger tumors and poorer survival, while treatment with W54011 reduced tumor size. CONCLUSIONS C5a promotes the growth, invasion, and stemness of GBM-TS, and inhibition of C5a using W54011 may have therapeutic potential for patients with high C5a expression. These results provide insight into the underlying mechanisms of GBM progression and establish a knowledge base for the clinical efficacy of W54011 in GBM treatment.

Extracellular vesicle lipids in cancer immunoevasion

Recent studies have revealed that cancer cell-derived extracellular vesicles (EVs) modulate immunological responses. Lipids have diverse biological functions, and are known to promote tumor malignancy. However, the immunoevasive roles of EV lipids in cancer progression remain poorly understood. Nevertheless, the study of cancer cell-derived EV lipids holds great promise for diagnostic and therapeutic interventions.

Proteolytic cleavage of membrane proteins by membrane type-1 MMP regulates cancer malignant progression.

Strategies to develop cancer therapies using inhibitors that target matrix metalloproteinases (MMPs), particularly membrane type-1 MMP (MT1-MMP), have failed. This is predominantly attributed to the specificity of MMP inhibitors and numerous functions of MMPs; therefore, targeting substrates with such broad specificity can lead to off-target effects. Thus, new drug development for cancer therapeutics should focus on the ability of MT1-MMP to break down substrates, such as functional cell membrane proteins, to regulate the functions of these proteins that promote tumor malignancy. In this review, we discuss the mechanism by which proteolysis of cell surface proteins by MT1-MMP promotes progression of malignant tumor cells. In addition, we discuss the two protein fragments generated by limited cleavage of erythropoietin-producing hepatoma receptor tyrosine kinase A2 (EphA2-NF, -CF), which represent a promising basis for developing new cancer therapies and diagnostic techniques.

Metabolic and Nonmetabolic Functions of PSAT1 Coordinate Signaling Cascades to Confer EGFR Inhibitor Resistance and Drive Progression in Lung Adenocarcinoma.

Metabolic and nonmetabolic functions of PSAT1 confer EGFR inhibitor resistance and promote metastasis in lung adenocarcinoma, suggesting therapeutic targeting of PSAT1 may attenuate the malignant features of lung cancer.

Circulating monocytes associated with anti-PD-1 resistance in human biliary cancer induce Tcell paralysis.

Suppressive myeloid cells can contribute to immunotherapy resistance, but their role in response to checkpoint inhibition (CPI) in anti-PD-1 refractory cancers, such as biliary tract cancer (BTC), remains elusive. We use multiplexed single-cell transcriptomic and epitope sequencing to profile greater than 200,000 peripheral blood mononuclear cells from advanced BTC patients (n= 9) and matched healthy donors (n= 8). Following anti-PD-1 treatment, CD14+ monocytes expressing high levels of immunosuppressive cytokines and chemotactic molecules (CD14CTX) increase in the circulation of patients with BTC tumors that are CPI resistant. CD14CTX can directly suppress CD4+ Tcells and induce SOCS3 expression in CD4+ Tcells, rendering them functionally unresponsive. The CD14CTX gene signature associates with worse survival in patients with BTC as well as in other anti-PD-1 refractory cancers. These results demonstrate that monocytes arising after anti-PD-1 treatment can induce Tcell paralysis as a distinct mode of tumor-mediated immunosuppression leading to CPI resistance.

TLR/WNT: A Novel Relationship in Immunomodulation of Lung Cancer.

The most frequent cause of death by cancer worldwide is lung cancer, and the 5-year survival rate is still very poor for patients with advanced stage. Understanding the crosstalk between the signaling pathways that are involved in disease, especially in metastasis, is crucial to developing new targeted therapies. Toll-like receptors (TLRs) are master regulators of the immune responses, and their dysregulation in lung cancer is linked to immune escape and promotes tumor malignancy by facilitating angiogenesis and proliferation. On the other hand, over-activation of the WNT signaling pathway has been reported in lung cancer and is also associated with tumor metastasis via induction of Epithelial-to-mesenchymal-transition (EMT)-like processes. An interaction between both TLRs and the WNT pathway was discovered recently as it was found that the TLR pathway can be activated by WNT ligands in the tumor microenvironment; however, the implications of such interactions in the context of lung cancer have not been discussed yet. Here, we offer an overview of the interaction of TLR-WNT in the lung and its potential implications and role in the oncogenic process.

ASPM and TROAP gene expression as potential malignant tumor markers.

BackgroundAlthough increasing evidence supports a vital role for assembly factor for spindle microtubules (ASPM) and trophinin-associated protein (TROAP) in the tumorigenesis of some cancers, no systematic pancancer analyses of ASPM and TROAP have been performed. Thus, we aimed to investigate the potential functions of ASPM and TROAP across 31 cancer types.MethodsBased on datasets from The Cancer Genome Atlas (TCGA), Human Protein Atlas (HPA), Gene-Cloud of Biotechnology Information (GCBI) and Gene Expression Omnibus (GEO), we employed an array of bioinformatics methods to explore the potential oncogenic roles of ASPM and TROAP.ResultsASPM and TROAP, which were highly expressed in most cancers and presented a strict positive correlation, led to a decreased life expectancy among cancer patients. ASPM and TROAP both regulated cell replication in the S&G2 phase of the cell cycle. Through a protein-protein interaction network (PPI) analysis of ASPM and TROAP, we found that cell division cycle 20 (CDC20) was regulated by TROAP and functioned upstream of ASPM. Thus, TROAP can regulate the role of ASPM in cancers.ConclusionsThe ASPM and TROAP have a significant positive correlation and similar expression profiles, and promote tumor malignancy and development in the S&G2 phase of the cell cycle. Since ASPM is one of the downstream targets of TROAP, TROAP and especially ASPM may be potential tumor makers and promising targets for therapeutic strategy.

P62 Promotes Malignancy of Hepatocellular Carcinoma by Regulating the Secretion of Exosomes and the Localization of β-Catenin.

p62 is a multi-domain protein and participates in a variety of cellular biological activities. p62 is also related to tumor malignancy. However, the underlying molecular mechanism of p62 regulating the progression of hepatocellular carcinoma (HCC) remains unclear. The expression levels of p62 in HCC tissues and adjacent non-tumor tissues were confirmed using the TCGA dataset and immunohistochemistry. Stable p62-overexpressing HepG2 cells and p62-knockdown MHCC97H cells were established with lentiviral vectors. Cell proliferation, migration, and invasion assays were carried out to investigate the role of p62 in HCC cells and HCC-derived exosomes. The relationship between p62 and β-catenin was investigated by immunofluorescence and co-immunoprecipitation assays. Male nude mice (BALB/c-nu/nu) were used to establish the xenograft tumors. We found that p62 was significantly upregulated in HCC, and a high level of p62 indicated the promotion of malignancy including cell proliferation, migration, and invasion. Exosomes derived from p62-overexpressing HepG2 also demonstrated the ability to promote tumor malignancy. Immunofluorescence and co-immunoprecipitation assays indicated that p62 interacts with β-catenin and regulates the localization of β-catenin to affect the intercellular junction. p62 also promotes tumor growth of HCC and down-regulates the expression of β-catenin in vivo. The results of this study concluded that p62 promotes the malignancy of HCC by regulating the secretion of exosomes and the localization of β-catenin. These findings may provide new ideas for the diagnosis and treatment of HCC.

Bromodomain-containing protein 9 is a prognostic biomarker associated with immune infiltrates and promotes tumor malignancy through activating notch signaling pathway in negative HIF-2α clear cell renal cell carcinoma.

HIF-2α selective inhibitor showed successful efficacy in sensitive clear cell renal cell carcinoma (ccRCC) presenting higher levels of HIF-2α compared to resistant tumors with low level of HIF-2α (negative HIF-2α ccRCC). Currently, negative HIF-2α ccRCC lacks truly effective therapeutic agents to improve the outcomes. Bromodomain-containing protein 9 (BRD9) plays a critical role in human hepatocellular carcinoma, squamous cell lung cancer, acute myeloid leukemia, and so on. However, expression and biological role of BRD9 in negative HIF-2α ccRCC is poorly understood. Clinically, we demonstrated that expression of BRD9 in negative HIF-2α ccRCC tissues was higher than that in positive HIF-2α ccRCC. Moreover, high BRD9 expression was correlated with unfavorable clinicopathological features and predicted the poor overall survival of negative HIF-2α ccRCC patients. Functionally, BRD9 knockout resulted in reduced proliferation, migration and invasion of negative HIF-2α ccRCC cells (Caki-2). In addition, BRD9 was related to the TIIC infiltration level in negative HIF-2α ccRCC tissues. Mechanistically, Gene set enrichment analysis (GSEA) showed that BRD9 was closely related to Notch signaling pathway. BRD9 knockout resulted in reduced mRNA level of Hes1 and Notch1 in negative HIF-2α ccRCC in vitro. The overexpression of NICD (Notch intracellular domain) enhanced malignant behaviors of Caki-2 cells with BRD9 knockout. And Notch inhibition led to attenuation of cell growth and reduced migration and invasion in Caki-2 cells. Overall, our results identified that BRD9 promotes the proliferation, migration and invasion of negative HIF-2α ccRCC cells by targeting Notch signaling pathway and serve as a promising biomarker for negative HIF-2α ccRCC.

Interaction between Ras and Src clones causes interdependent tumor malignancy via Notch signaling in Drosophila.

Cancer tissue often comprises multiple tumor clones with distinct oncogenic alterations such as Ras or Src activation, yet the mechanism by which tumor heterogeneity drives cancer progression remains elusive. Here, we show in Drosophila imaginal epithelium that clones of Ras- or Src-activated benign tumors interact with each other to mutually promote tumor malignancy. Mechanistically, Ras-activated cells upregulate the cell-surface ligand Delta while Src-activated cells upregulate its receptor Notch, leading to Notch activation in Src cells. Elevated Notch signaling induces the transcriptional repressor Zfh1/ZEB1, which downregulates E-cadherin and cell death gene hid, leading to Src-activated invasive tumors. Simultaneously, Notch activation in Src cells upregulates the cytokine Unpaired/IL-6, which activates JAK-STAT signaling in neighboring Ras cells. Elevated JAK-STAT signaling upregulates the BTB-zinc-finger protein Chinmo, which downregulates E-cadherin and thus generates Ras-activated invasive tumors. Our findings provide a mechanistic explanation for how tumor heterogeneity triggers tumor progression via cell-cell interactions.

Elevated fibroblast growth factor-inducible 14 expression transforms proneural-like gliomas into more aggressive and lethal brain cancer.

High-grade gliomas (HGGs) are aggressive, treatment-resistant, and often fatal human brain cancers. The TNF-like weak inducer of apoptosis (TWEAK)/fibroblast growth factor-inducible 14 (Fn14) signaling axis is involved in tissue repair after injury and constitutive signaling has been implicated in the pathogenesis of numerous solid cancers. The Fn14 gene is expressed at low levels in the normal, uninjured brain but is highly expressed in primary isocitrate dehydrogenase wild-type and recurrent HGGs. Fn14 signaling is implicated in numerous aspects of glioma biology including brain invasion and chemotherapy resistance, but whether Fn14 overexpression can directly promote tumor malignancy has not been reported. Here, we used the replication-competent avian sarcoma-leukosis virus/tumor virus A system to examine the impact of Fn14 expression on glioma development and pathobiology. We found that the sole addition of Fn14 to an established oncogenic cocktail previously shown to generate proneural-like gliomas led to the development of highly invasive and lethal brain cancer with striking biological features including extensive pseudopalisading necrosis, constitutive canonical and noncanonical NF-κB pathway signaling, and high plasminogen activator inhibitor-1 (PAI-1) expression. Analyses of HGG patient datasets revealed that high human PAI-1 gene (SERPINE1) expression correlates with shorter patient survival, and that the SERPINE1 and Fn14 (TNFRSF12A) genes are frequently co-expressed in bulk tumor tissues, in tumor subregions, and in malignant cells residing in the tumor microenvironment. These findings provide new insights into the potential importance of Fn14 in human HGG pathobiology and designate both the NF-κB signaling node and PAI-1 as potential targets for therapeutic intervention. MAIN POINTS: This work demonstrates that elevated levels of the TWEAK receptor Fn14 in tumor-initiating, neural progenitor cells leads to the transformation of proneural-like gliomas into more aggressive and lethal tumors that exhibit constitutive NF-κB pathway activation and plasminogen activator inhibitor-1 overexpression.

MCT4 Promotes Tumor Malignancy in F98 Glioma Cells

Monocarboxylate transporter 4 (MCT4, SLC16A3) is elevated under hypoxic conditions in many malignant tumors including gliomas. Moreover, MCT4 expression is associated with shorter overall survival. However, the functional consequences of MCT4 expression on the distinct hallmarks of cancer have not yet been explored at the cellular level. Here, we investigated the impact of MCT4 overexpression on proliferation, survival, cell death, migration, invasion, and angiogenesis in F98 glioma cells. Stable F98 glioma cell lines with MCT4 overexpression, normal expression, and knockdown were generated. Distinct hallmarks of cancer were examined using in silico analysis, various in vitro cell culture assays, and ex vivo organotypic rat brain slice culture model. Consistent with its function as lactate and proton exporter, MCT4 expression levels correlated inversely with extracellular pH and proportionally with extracellular lactate concentrations. Our results further indicate that MCT4 promotes proliferation and survival by altered cell cycle regulation and cell death mechanisms. Moreover, MCT4 overexpression enhances cell migration and invasiveness via reorganization of the actin cytoskeleton. Finally, MCT4 inhibition mitigates the induction of angiogenesis, suggesting that MCT4 also plays a crucial role in tumor-related angiogenesis. In summary, our data highlight MCT4/SLC16A3 as a key gene for distinct hallmarks of tumor malignancy in glioma cells.

Mutant KRAS triggers functional reprogramming of tumor-associated macrophages in colorectal cancer

Oncogenic KRAS has been previously identified to act in a cell-intrinsic manner to modulate multiple biological functions of colorectal cancer (CRC). Here, we demonstrate a cell-extrinsic role of KRAS, where KRAS engages with the tumor microenvironment by functional reprogramming of tumor-associated macrophages (TAMs). In human CRC specimens, mutant KRAS positively correlates with the presence of TAMs. Mutationally activated KRAS in tumor cells reprograms macrophages to a TAM-like phenotype via a combination effect of tumor-derived CSF2 and lactate. In turn, KRAS-reprogrammed macrophages were shown to not only promote tumor progression but also induce the resistance of tumor cells to cetuximab therapy. Mechanistically, KRAS drives the production of CSF2 and lactate in tumor cells by stabilizing hypoxia-inducible factor-1α (HIF-1α), a transcription factor that controls the expression of CSF2 and glycolytic genes. Mutant KRAS increased the production of reactive oxygen species, an inhibitor of prolyl hydroxylase activity which decreases HIF-1α hydroxylation, leading to enhanced HIF-1α stabilization. This cell-extrinsic mechanism awards KRAS a critical role in engineering a permissive microenvironment to promote tumor malignancy, and may present new insights on potential therapeutic defense strategies against mutant KRAS tumors.

PRRX1 promotes malignant properties in human osteosarcoma

Paired related homeobox 1 (PRRX1) is a marker of limb bud mesenchymal cells, and deficiency of p53 or Rb in Prrx1-positive cells induces osteosarcoma in several mouse models. However, the regulatory roles of PRRX1 in human osteosarcoma have not been defined. In this study, we performed PRRX1 immunostaining on 35 human osteosarcoma specimens to assess the correlation between PRRX1 level and overall survival. In patients with osteosarcoma, the expression level of PRRX1 positively correlated with poor prognosis or the ratio of lung metastasis. Additionally, we found PRRX1 expression on in 143B cells, a human osteosarcoma line with a high metastatic capacity. Downregulation of PRRX1 not only suppressed proliferation and invasion but also increased the sensitivity to cisplatin and doxorubicin. When 143B cells were subcutaneously transplanted into nude mice, PRRX1 knockdown decreased tumor sizes and rates of lung metastasis. Interestingly, forskolin, a chemical compound identified by Connectivity Map analysis using RNA expression signatures during PRRX1 knockdown, decreased tumor proliferation and cell migration to the same degree as PRRX1 knockdown. These results demonstrate that PRRX1 promotes tumor malignancy in human osteosarcoma.

Stromal SOX2 Upregulation Promotes Tumorigenesis through the Generation of a SFRP1/2-Expressing Cancer-Associated Fibroblast Population.

Cancer-associated fibroblasts (CAFs) promote tumor malignancy, but the precise transcriptional mechanisms regulating the acquisition of the CAF phenotype are not well understood. We show that the upregulation of SOX2 is central to this process, which is repressed by protein kinase Cζ (PKCζ). PKCζ deficiency activates the reprogramming of colonic fibroblasts to generate a predominant SOX2-dependent CAF population expressing the WNT regulator Sfrp2 as its top biomarker. SOX2 directly binds the Sfrp1/2 promoters, and the inactivation of Sox2 or Sfrp1/2 in CAFs impaired the induction of migration and invasion of colon cancer cells, as well as their tumorigenicity invivo. Importantly, recurrence-free and overall survival of colorectal cancer (CRC) patients negatively correlates with stromal PKCζ levels. Also, SOX2 expression in the stroma is associated with CRC T invasion and worse prognosis of recurrence-free survival. Therefore, the PKCζ-SOX2 axis emerges as a critical step in the control of CAF pro-tumorigenic potential.