Growth Of Colorectal Cancer Xenografts Research Articles

METTL17 coordinates ferroptosis and tumorigenesis by regulating mitochondrial translation in colorectal cancer

Ferroptosis, an iron-dependent lipid peroxidation-induced form of regulated cell death, shows great promise as a cancer therapy strategy. Despite the critical role of mitochondria in ferroptosis regulation, the underlying mechanisms remain elusive. This study reveals that the mitochondrial protein METTL17 governs mitochondrial function in colorectal cancer (CRC) cells through epigenetic modulation. Bioinformatic analysis establishes that METTL17 expression positively correlates with ferroptosis resistance in cancer cells and is up-regulated in CRC. Depletion of METTL17 sensitizes CRC cells to ferroptosis, impairs cell proliferation, migration, invasion, xenograft tumor growth, and AOM/DSS-induced CRC tumorigenesis. Furthermore, suppression of METTL17 disrupts mitochondrial function, energy metabolism, and enhances intracellular and mitochondrial lipid peroxidation and ROS levels during ferroptotic stress. Mechanistically, METTL17 inhibition significantly reduces mitochondrial RNA methylation, including m4C, m5C, m3C, m7G, and m6A, leading to impaired translation of mitochondrial protein-coding genes. Additionally, the interacting proteins associated with METTL17 are essential for mitochondrial gene expression, and their knockdown sensitizes CRC cells to ferroptosis and inhibits cell proliferation. Notably, combined targeting of METTL17 and ferroptosis in a therapeutic approach effectively suppresses CRC xenograft growth in vivo. This study uncovers the METTL17-mediated defense mechanism for cell survival and ferroptosis in mitochondria, highlighting METTL17 as a potential therapeutic target for CRC.

The Combination of Inositol Hexaphosphate and Inositol Inhibits Metastasis of Colorectal Cancer Cells by Upregulating Claudin 7.

Inositol hexaphosphate (IP6), a widely found natural bioactive substance in grains, effectively inhibits the progression of colorectal cancer (CRC) when used in combination with inositol (INS). We previously showed that supplementation of IP6 and INS upregulated the claudin 7 gene in orthotropic CRC xenografts in mice. The aim of this study was to elucidate the role of claudin 7 in the inhibition of CRC metastasis by IP6 and INS, and explore the underlying mechanisms. We found that IP6, INS and their combination inhibited the epithelial-mesenchymal transition (EMT) of colon cancer cell lines (SW480 and SW620), as indicated by upregulation of claudin 7 and E-cadherin, and downregulation of N-cadherin. The effect of IP6 and INS was stronger compared to either agent alone (combination index < 1). Furthermore, the silencing of the claudin 7 gene diminished the anti-metastatic effects of IP6 and INS on SW480 and SW620 cells. Consistent with in vitro findings, the combination of IP6 and INS suppressed CRC xenograft growth in a mouse model, which was neutralized by claudin 7. Taken together, the combination of IP6 and INS can inhibit CRC metastasis by blocking EMT of tumor cells through upregulation of claudin 7.

Metformin-based carbon dots based on biguanide functional groups for simultaneous chelation of copper ions and inhibitable colorectal cancer therapy

Colorectal cancer (CRC) is the most common malignancy-related cause of death worldwide. The prognosis of CRC patients is strongly correlated with elevated plasma copper. The quantitative detection of plasma copper is highly essential for the field of biomedicine, and our hypothesis was that plasma copper may be a therapeutic target for treating CRC. Here, we developed metformin-based carbon dots (MFCDs). MFCDs have strong photoluminescence at 460 nm, which is quenched by Cu2+. Cu2+ concentration and the fluorescence emission intensity of MFCDs are significantly associated (linear range of 0.5–40 μM with a detection limit of 0.30 μM). Additionally, administration of MFCDs significantly inhibited the growth of CRC xenografts in mice caused by the existence of biguanide functional groups. MFCDs treatment led to the increase of reactive oxygen species and subsequent DNA damage and cell cycle arrest. This study showed that the biguanide functional groups of MFCDs chelate with Cu2+, resulting in the reduction of Cu/Zn-superoxide dismutase and glutathione, which eventually reduces antioxidant capacity and ultimately induces cell apoptosis. These results indicate that MFCDs provide a novel approach for anticancer therapy.

Abstract 5510: TAS102 synergizes with regorafenib against colorectal and gastric cancer cells

Abstract TAS-102 is an oral formulation consisting of trifluridine (FTD) and thymidine phosphorylase inhibitor tipiracil hydrochloride (TPI). Regorafenib is a multi-targeted tyrosine kinase inhibitor, it inhibits the activities of VEGFR2 and 3, Ret, Kit, PDGFR and Raf kinases and results in the inhibition of tumor angiogenesis and cell proliferation. TAS102 or regorafenib monotherapy can lead to an overall survival benefit in metastatic colorectal cancer (mCRC) patient previously treated with conventional chemotherapy and target therapy (Arnold et al., 2018). TAS102 in combination with bevacizumab, a monoclonal antibody against vascular endothelial growth factor A (VEGF-A), is associated with a significant and clinically relevant improvement in progression-free survival in colorectal cancer (C-TASK FORCE)(Kuboki et al., 2017; Pfeiffer et al., 2020). FTD can synergize with nintedanib to inhibit the growth of colorectal cancer xenografts(Suzuki, Nakagawa, Matsuoka, &amp; Takechi, 2016). We previously reported that regorafenib combined with a fluoropyrimidine can delay disease progression in case reports of multidrug-resistant mCRC patients(Marks et al., 2015). Therefore, we hypothesized that the combination of TAS102 and regorafenib may be active in CRC and other gastrointestinal (GI) cancers, and may in the future provide a treatment option for patients with advanced GI cancer. We investigated the therapeutic effect of TAS102 in combination with regorafenib in preclinical studies employing cell culture, colonosphere assays that enrich for cancer stem cells, and in vivo. We found that TAS102 in combination with regorafenib has synergistic activity against multiple GI cancers in vitro including colorectal and gastric cancer, but not liver cancer cells. TAS102 inhibits colonosphere formation and this effect is potentiated by regorafenib. In vivo anti-tumor effects of TAS102 plus regorafenib appear to be due to anti-proliferative effects, necrosis and angiogenesis inhibition. Growth inhibition by TAS102 plus regorafenib occurs in xenografted tumors regardless of p53, KRAS or BRAF mutations, although more potent tumor suppression was observed with wild-type p53. Regorafenib significantly inhibits TAS102-induced angiogenesis and microvessel density in xenografted tumors, and inhibits TAS102-induced ERK1/2 activation regardless of RAS or BRAF status in vivo. Collectively, TAS102 plus regorafenib is a synergistic drug combination in preclinical models of GI cancer, with regorafenib suppressing TAS102-induced increase in microvessel density and p-ERK as contributing mechanisms. The drug combination may be further tested in gastric and other GI cancers. Citation Format: Jun Zhang, Lanlan Zhou, Shuai Zhao, Wafik S. El-Deiry. TAS102 synergizes with regorafenib against colorectal and gastric cancer cells. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5510.

A Novel Mechanism of Endoplasmic Reticulum Stress- and c-Myc-Degradation-Mediated Therapeutic Benefits of Antineurokinin-1 Receptor Drugs in Colorectal Cancer.

The neurokinin‐1 receptor (NK‐1R) antagonists are approved as treatment for chemotherapy‐associated nausea and vomiting in cancer patients. The emerging role of the substance P‐NK‐1R system in oncogenesis raises the possibility of repurposing well‐tolerated NK‐1R antagonists for cancer treatment. This study reports that human colorectal cancer (CRC) patients with high NK‐1R expression have poor survival, and NK‐1R antagonists SR140333 and aprepitant induce apoptotic cell death in CRC cells and inhibit CRC xenograft growth. This cytotoxicity induced by treatment with NK‐1R antagonists is mediated by induction of endoplasmic reticulum (ER) stress. ER stress triggers calcium release, resulting in the suppression of prosurvival extracellular signal‐regulated kinase (ERK)‐c‐Myc signaling. Along with ER calcium release, one ER stress pathway mediated by protein kinase RNA‐like ER kinase (PERK) is specifically activated, leading to increased expression of proapoptotic C/EBP‐homologous protein (CHOP). Moreover, NK‐1R antagonists enhance the efficacy of chemotherapy by increasing the sensitivity and overcoming resistance to 5‐fluorouracil in CRC cells through the induction of sustained ER stress and the consequent suppression of ERK‐c‐Myc signaling both in vitro and in vivo. Collectively, the findings provide novel mechanistic insights into the efficacy of NK‐1R antagonists either as a single agent or in combination with chemotherapy for cancer treatment.

Abstract 2648: A dual functional agent inhibits the angiogenesis and DNA synthesis resulting in the growth suppression of consensus molecular subtypes 1 and 4 in colorectal cancer xenografts

Abstract Purpose: We have synthesized a series of bifunctional molecules, which are able to induce DNA interstrand crosslinks and inhibit angiogenesis as potent anticancer agents [1] and leads to develop new hybrids molecules. To analyze one of the novel bifunctional agent BO-2762 activity in consensus molecular subtype (CMS) classified as colorectal cancer (CRC) which are classified into four subtypes [ CMS1, MSI-immune; CMS2, epithelial and canonical; CMS3, epithelial and metabolic; and CMS4, mesenchymal] in in vitro and in vivo models. Experimental Design: We analyzed the anticancer effect of BO-2762 in CMS primary colorectal cancer cells which are reported in previous studies [2] and their respective xenografts (CMS-1: LoVo; CMS-2: LS1034; CMS-3: HT-29 and CMS-4: SW620). CMS provided a new platform to analyze BO-2762 functionalized subtype-specific sensitivity in CRC. Results: BO-2762 has a distinct bifunctional activity by DNA crosslinking in CRC cells and inhibiting angiogenesis in endothelial cells at IC50 of nanomolar to micromolar ranges. Angiogenesis inhibition was likely due to the suppression of VEGFR-2 phosphorylation in EA.hy 926 cells. Additionally, BO-2762 could inhibit cell migration, invasion, and induce apoptotic cell death in CRC. In our observation, no subtype-sensitivity has observed in in vitro conditions as reported in previous studies [3]. Using xenograft models, 20 mg/kg BO-2762 suppressed remarkably LoVo (CMS-1), and SW620 (CMS-4) subtypes, moderately in LS1034 (CMS-2) which was administrated via i.v. injection. However, HT29 cells classified as metabolic dysregulated, which is the CMS-3 subtype, have shown resistance to BO-2762. Conclusion: BO-2762 functions as an angiogenesis inhibitor by inhibiting the phosphorylation of VEGFR2 and inhibits the DNA synthesis by cross-linking the DNA. Consequently, BO-2762 was shown to profoundly suppress the growth of CRC xenografts of CMS-1 and 4 subtypes but not that of CMS-2 and 3. Accordingly, BO-2762 has great potential for further development as a specific anti-CRC agent against CMS-1 and 4 subtypes and lead the further investigation on how to overcome the resistance of metabolic dysregulated CMS-3 subtype as a fundamental question that warrants our investigation.

A438079 affects colorectal cancer cell proliferation, migration, apoptosis, and pyroptosis by inhibiting the P2X7 receptor

BackgroundOur previous study identified elevated expression of the P2X7 receptor (P2X7R) in colorectal cancer (CRC) patients, suggesting the receptor is a target for predicting poor disease prognosis. A438079 is a highly selective P2X7R antagonist, however, no studies have identified A438079 effects and mechanisms toward the biological behavior of CRC cells, and its therapeutic in vivo potential in CRC nude mice. MethodsThe CRC cell lines, HCT-116 and SW620 were treated with 10 μM A438079, after which proliferation, migration, invasion, and apoptosis were assessed. SW620 cell xenografted BALB/c nude male mice were randomly divided into control, 5-FU, and A438079 groups. Mouse weight and tumor dimensions were also measured every two days. Furthermore, the expression of apoptosis related indicators (P2X7R, Bcl-2, Bax, caspase9, cleaved caspase9, caspase3, and cleaved caspase3) and pyroptosis related indicators (NLRP3, ASC, cleaved caspase1, and interleukin (IL)-β) were investigated in vitro and in vivo. ResultsA438079 inhibited HCT-116 and SW620 cell proliferation, invasion and migration, and inhibited the growth of CRC xenografts in nude mice. A438079 promoted apoptosis via the Bcl-2/caspase9/caspase3 pathway and inhibited pyroptosis through the NLRP3/caspase1 pathway by inhibiting P2X7R in vitro and in vivo. ConclusionsWe preliminarily confirmed the therapeutic potential of A438079 toward CRC, and we provide a sound theoretical basis for A438079 as a new drug for the clinical treatment of CRC.

Ruxolitinib induces apoptosis of human colorectal cancer cells by downregulating the JAK1/2-STAT1-Mcl-1 axis.

Under pathological conditions, the Janus kinase (JAK)/STAT signaling pathway can regulate the proliferation, differentiation and migration of tumor cells, including colorectal cancer (CRC). CRC is the third major types of cancer among males and the second among females worldwide. In China, CRC is the fifth common cancer among both males and females. Western blotting, flow cytometry, RNA interference, immunoprecipitation, xenografts models, and immunohistochemical staining were carried out to evaluate the possible mechanisms of acton of ruxolitinib. The present data suggested that ruxolitinib can suppress CRC cell proliferation by inducing apoptosis. Firstly, JAK1/2-STAT1 was identified as the target of ruxolitinib. Then, ruxolitinib downregulated myeloid cell leukemia-1 (Mcl-1) mRNA level and decreased its protein level, which enabled Bak to trigger CRC apoptosis. Furthermore, ruxolitinib exerted potent activity against CRC xenograft growth in vivo. High expression of phosphorylated STAT1 (S727) was also confirmed in 44 pairs of human colon carcinoma and adjacent normal tissues. Taken together, the results showed that ruxolitinib decreased JAK1/2-STAT1-Mcl-1 protein level and effectively suppressed CRC cell proliferation in vitro and in vivo. Therefore, ruxolitinib could be a promising anticancer agent for CRC treatment.

Circular RNA NOX4 promotes the development of colorectal cancer via the microRNA‑485‑5p/CKS1B axis.

Colorectal cancer (CRC) is a common malignancy globally. The aim of the present study was to explore the role and the working mechanism of circular RNA NADPH oxidase 4 (circNOX4; circBase ID, hsa_circ_0023990) in CRC. Reverse transcription-quantitative (RT-q)PCR was used to examine the expression of circNOX4, NOX4 mRNA and microRNA (miR)-485-5p in CRC tissues and cell lines. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and Transwell assays were performed to analyze CRC cell viability and motility. The glycolytic ability of CRC cells was assessed by measuring glucose consumption, lactate production, extracellular acidification and O2 consumption rates using commercial kits. The starBase database was used to predict the targets of circNOX4 and miR-485-5p, and the interaction was confirmed by dual-luciferase reporter and RNA immunoprecipitation assays. A murine xenograft model was established to verify the role of circNOX4 in CRC in vivo. The results demonstrated that the expression of circNOX4 was upregulated in CRC tissues and cell lines compared with that in adjacent normal tissues and a normal colon epithelial cell line, respectively. The expression of circNOX4 was negatively associated with the prognosis of patients with CRC. CircNOX4 silencing suppressed the proliferation, migration, invasion and glycolysis of CRC cells. miR-485-5p was identified as a target of circNOX4. CircNOX4 promoted CRC progression by sponging miR-485-5p. miR-485-5p was demonstrated to bind to the 3′ untranslated region (UTR) of CDC28 protein kinase regulatory subunit 1B (CKS1B). miR-485-5p overexpression-mediated malignant properties of CRC cells were partly reversed by the transfection with the CKS1B overexpression plasmid. CircNOX4 silencing restrained the CRC xenograft growth in vivo. Collectively, the results of the present study demonstrated that circNOX4 may serve an oncogenic role in CRC by promoting the proliferation, migration, invasion and glycolysis of CRC cells via the miR-485-5p/CKS1B axis.

Ciclopirox activates PERK-dependent endoplasmic reticulum stress to drive cell death in colorectal cancer

Ciclopirox (CPX) modulates multiple cellular pathways involved in the growth of a variety of tumor cell types. However, the effects of CPX on colorectal cancer (CRC) and the underlying mechanisms for its antitumor activity remain unclear. Herein, we report that CPX exhibited strong antitumorigenic properties in CRC by inducing cell cycle arrest, repressing cell migration, and invasion by affecting N-cadherin, Snail, E-cadherin, MMP-2, and MMP-9 expression, and disruption of cellular bioenergetics contributed to CPX-associated inhibition of cell growth, migration, and invasion. Interestingly, CPX-induced reactive oxygen species (ROS) production and impaired mitochondrial respiration, whereas the capacity of glycolysis was increased. CPX (20 mg/kg, intraperitoneally) substantially inhibited CRC xenograft growth in vivo. Mechanistic studies revealed that the antitumor activity of CPX relies on apoptosis induced by ROS-mediated endoplasmic reticulum (ER) stress in both 5-FU-sensitive and -resistant CRC cells. Our data reveal a novel mechanism for CPX through the disruption of cellular bioenergetics and activating protein kinase RNA-like endoplasmic reticulum kinase (PERK)-dependent ER stress to drive cell death and overcome drug resistance in CRC, indicating that CPX could potentially be a novel chemotherapeutic for the treatment of CRC.

Prodigiosin impairs autophagosome-lysosome fusion that sensitizes colorectal cancer cells to 5-fluorouracil-induced cell death.

Chemotherapy failure is a major cause of recurrence and poor prognosis in colorectal cancer (CRC) patients. Inhibition of autophagy is a promising strategy to augment the cytotoxicity of chemotherapeutic agents. We identified prodigiosin, a secondary metabolite produced by various bacteria, as a novel autophagy inhibitor that interfered with the autophagic flux in CRC cells by blocking autophagosome-lysosome fusion and lysosomal cathepsin maturation, resulting in the accumulation of LC3B-II and SQSTM. Suppression of autophagy by prodigiosin sensitized the CRC cells to 5-fluorouracil (5-Fu) in vitro, and the combination treatment markedly reduced cancer cell viability partly via caspase-dependent apoptosis. Furthermore, prodigiosin and 5-Fu synergistically inhibited CRC xenograft growth in vivo without any adverse effects. In conclusion, prodigiosin inhibits late stage autophagy and sensitizes tumor cells to 5-Fu, indicating its therapeutic potential in CRC.

Abstract 220: U3-1402, a novel HER3-targeting ADC, inhibits the tumor growth of colorectal cancer xenografts

Abstract Background: HER3 (human epidermal growth factor receptor 3) is a member of the HER family and overexpressed in a broad range of cancer types including colorectal cancer. HER3 targeted therapies such as anti-HER3 antibodies have been investigated in clinical trials; however, no HER3-targeting therapy has been approved to date. U3-1402 is a novel antibody drug conjugate (ADC) composed of a fully human anti-HER3 antibody (patritumab) and a novel topoisomerase I inhibitor (DXd) which is conjugated via an enzymatically cleavable peptide-linker with high drug antibody ratio (DAR: 7-8 to 1). Purpose: To investigate the antitumor efficacy of U3-1402 in HER3-expressing colorectal cancer xenograft models. Material and methods: The following cell lines were used in this study; WiDr, Colo320DM, and DiFi with KRAS wild type, DLD-1, HCT15, HCT116, LoVo, SW480, and SW620 harboring KRAS mutation. The sensitivities of 9 colorectal cancer cell lines to DXd were evaluated by in vitro cell killing assay. Cells were treated with DXd at different concentrations (0.5pM to 500nM) over 144 hours, and the 50% inhibitory concentration (IC50) values were determined. Cell surface HER3 antigen was quantified by flow cytometry. In vivo screening assay and tumor growth inhibition assay were performed in tumor xenograft models exhibiting a range of HER3 expression levels. In addition, the efficacy of U3-1402 was compared to that of parental antibody patritumab, CPT-11, control-ADC, and saline in SW620 tumor xenograft model harboring KARS mutation. All results were expressed as mean ± standard deviation (SD) and statistical significance was analyzed using ANOVA with Dunnet multiple comparison. Results: In in vitro study, the range of IC50 value of DXd for each cell line was 2.16 ± 0.11 nM to 16.04 ± 0.10 nM. Most of the cell lines were sensitive to DXd. In in vivo screening assay, the maximum regression from U3-1402 was observed in the tumor xenograft model of both DiFi (high HER3 expression; KRAS wild type) and SW620 (high HER3 expression; KRAS mutation). In in vivo tumor growth inhibition assay, the antitumor efficacy was dependent on the HER3 expression level. Notably, SW620 tumor growth was significantly suppressed with U3-1402 compared with that of saline group (p &amp;lt; 0.001) and had improved potency compared with CPT-11. Of note, no significant difference in tumor growth inhibition was observed amongst the treatments with the same dose of patritumab or control-ADC and saline. Tumor regression was only observed in U3-1402 treated group, and some of which achieved complete regression. Conclusions: The antitumor efficacy of U3-1402 in xenograft models was dependent on HER3 expression and did not show a clear relationship to KRAS mutation status. These results support further investigation of development strategies for U3-1402 in patients with HER3-expressing colorectal cancer. Citation Format: Shigehiro Koganemaru, Yasutoshi Kuboki, Yoshikatsu Koga, Takashi Kojima, Mayumi Yamauchi, Naoyuki Maeda, Takashi Kagari, Kenji Hirotani, Masahiro Yasunaga, Yasuhiro Matsumura, Toshihiko Doi. U3-1402, a novel HER3-targeting ADC, inhibits the tumor growth of colorectal cancer xenografts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 220.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

Systematic Functional Interrogation of Genes in GWAS Loci Identified ATF1 as a Key Driver in Colorectal Cancer Modulated by a Promoter-Enhancer Interaction

Genome-wide association studies (GWASs) have identified approximately 100 colorectal cancer (CRC) risk loci. However, the causal genes in these loci have not been systematically interrogated. We conducted a high-throughput RNA-interference functional screen to identify the genes essential for proliferation in the CRC risk loci of Asian populations. We found that ATF1, located in the 12q13.12 region, functions as an oncogene that facilitates cell proliferation; ATF1 has the most significant effect of the identified genes and promotes CRC xenograft growth by affecting cell apoptosis. Next, by integrating a fine-mapping analysis, a two-stage affected-controlstudy consisting of 6,213 affected individuals and 10,388 controls, and multipronged experiments, we elucidated that two risk variants, dbSNP: rs61926301 and dbSNP: rs7959129, that located in the ATF1 promoter and first intron, respectively, facilitate a promoter-enhancer interaction, mediated by the synergy of SP1 and GATA3, to upregulate ATF1 expression, thus synergistically predisposing to CRC risk (OR = 1.77, 95% CI = 1.42-2.21, p = 3.16× 10-7; Pmultiplicative-interaction = 1.20× 10-22; Padditive-interaction = 6.50× 10-3). Finally, we performed RNA-seq and ChIP-seq assays in CRC cells treated with ATF1 overexpression in order to dissect the target programs of ATF1. Results showed that ATF1 activates a subset of genes, including BRAF, NRAS, MYC, BIRC2, DAAM1, MAML2, STAT1, ID1, and NKD2, related to apoptosis, Wnt, TGF-β, and MAPK pathways, and these effects could cooperatively increase the risk of CRC. These findings reveal the clinical potential of ATF1 in CRC development and illuminate a promoter-enhancer interaction module between the ATF1 regulatory elements dbSNP: rs61926301 and dbSNP: rs7959129, and they bring us closer to understanding the molecular drivers of cancer.

Growth suppression of colorectal cancer expressing S492R EGFR by monoclonal antibody CH12

Colorectal cancer (CRC) is a common malignant tumor in the digestive tract, and 30%–85% of CRCs express epidermal growth factor receptors (EGFRs). Recently, treatments using cetuximab, also named C225, an anti-EGFR monoclonal antibody, for CRC have been demonstrated to cause an S492R mutation in EGFR. However, little is known about the biological function of S492R EGFR. Therefore, we attempted to elucidate its biological function in CRC cells and explore new treatment strategies for this mutant form. Our study indicated that EGFR and S492R EGFR accelerate the growth of CRC cells in vitro and in vivo and monoclonal antibody CH12, which specifically recognizes an EGFR tumor-specific epitope, can bind efficiently to S492R EGFR. Furthermore, mAb CH12 showed significantly stronger growth suppression activities and induced a more potent antibody-dependent cellular cytotoxicity effect on CRC cells bearing S492R EGFR than mAb C225. mAb CH12 obviously suppressed the growth of CRC xenografts with S492R EGFR mutations in vivo. Thus, mAb CH12 may be a promising therapeutic agent in treating patients with CRC bearing an S492R EGFR mutation.

Physciosporin suppresses the proliferation, motility and tumourigenesis of colorectal cancer cells

BackgroundLichens, which represent symbiotic associations of fungi and algae, are potential sources of numerous natural products. Physciosporin (PHY) is a potent secondary metabolite found in lichens and was recently reported to inhibit the motility of lung cancer cells via novel mechanisms. PurposeThe present study investigated the anticancer potential of PHY on colorectal cancer (CRC) cells. MethodsPHY was isolated from lichen extract by preparative TLC. The effect of PHY on cell viability, motility and tumourigenicity was elucidated by MTT assay, hoechst staining, flow cytometric analysis, transwell invasion and migration assay, soft agar colony formation assay, Western blotting, qRT-PCR and PCR array in vitro as well as tumorigenicity study in vivo. ResultsPHY decreased the viability of various CRC cell lines (Caco2, CT26, DLD1, HCT116 and SW620). Moreover, PHY elicited cytotoxic effects by inducing apoptosis at toxic concentrations. At non-toxic concentrations, PHY dose-dependently suppressed the invasion, migration and colony formation of CRC cells. PHY inhibited the motility of CRC cells by suppressing epithelial-mesenchymal transition and downregulating actin-based motility markers. In addition, PHY downregulated β-catenin and its downstream target genes cyclin-D1 and c-Myc. Moreover, PHY modulated KAI1 C-terminal-interacting tetraspanin and KAI1 expression, and downregulated the downstream transcription factors c-jun and c-fos. Finally, PHY administration showed considerable bioavailability and effectively decreased the growth of CRC xenografts in mice without causing toxicity. ConclusionPHY suppresses the growth and motility of CRC cells via novel mechanisms.

RAC1-GTP promotes epithelial-mesenchymal transition and invasion of colorectal cancer by activation of STAT3

Epithelial-mesenchymal transition (EMT) plays a critical role in initiating tumor invasion and metastasis of colorectal cancer (CRC), although the underlying mechanisms remain to be clarified. Herein, we demonstrate that the active form of Rac family small GTPase 1 (RAC1-GTP) is overexpressed in CRCs and promotes the EMT-mediated invasion of CRC cells through activation of the signal transducers and activators of transcription 3 (STAT3) pathway. Increased expression of RAC1-GTP in CRC tissues was positively correlated with the TNM stages of CRCs and indicated poor prognosis of CRC patients. Targeting RAC1-GTP activity by its specific inhibitor NSC23766 markedly suppressed the migration and invasion of CRC cells. Mechanistically, RAC1-GTP directly interacted with STAT3 to promote STAT3 phosphorylation, thus promoted EMT of CRC cells. Enforced expression of constitutively activated STAT3 (STAT3-C) abrogated the suppressive effect of RAC1-GTP disruption on the migration and invasion of CRC cells. Importantly, NSC23766 disrupted EMT in CRC cells and significantly diminished growth of CRC xenografts. Taken together, our data indicate that RAC1-GTP is an important player in EMT-mediated tumor invasion and a potential therapeutic target for CRCs.In this study the authors show that Rac family small GTPase 1 (RAC1-GTP) is overexpressed in colorectal cancer (CRC) and promotes epithelial-mesenchymal transition-mediated invasion of CRC cells through activation of the STAT3 pathway. Overexpression of RAC1-GTP in CRCs correlates with tumor progression and recurrence of CRCs, and predicts poor prognosis of CRC patients.

Alternative NF-κB signaling promotes colorectal tumorigenesis through transcriptionally upregulating Bcl-3.

Multiple studies have shown that chronic inflammation is closely related to the occurrence and development of colorectal cancer (CRC). Classical NF-κB signaling, the key factor in controlling inflammation, has been found to be of great importance to CRC development. However, the role of alternative NF-κB signaling in CRC is still elusive. Here, we found aberrant constitutive activation of alternative NF-κB signaling both in CRC tissue and CRC cells. Knockdown of RelB downregulates c-Myc and upregulates p27Kip1 protein level, which inhibits CRC cell proliferation and retards CRC xenograft growth. Conversely, overexpression of RelB increases proliferation of CRC cells. In addition, we revealed a significant correlation between Bcl-3 and RelB in CRC tissues. The expression of RelB was consistent with the expression of Bcl-3 and the phosphorylation of Bcl-3 downstream proteins p-Akt (S473) and p-GSK3β (S9). Bcl-3 overexpression can restore the phenotype changes caused by RelB knockdown. Importantly, we demonstrated that alternative NF-κB transcriptional factor (p52:RelB) can directly bind to the promoter region of Bcl-3 gene and upregulate its transcription. Moreover, the expression of RelB, NF-κB2 p52, and Bcl-3 was associated with poor survival of CRC patients. Taken together, these results represent that alternative NF-κB signaling may function as an oncogenic driver in CRC, and also provide new ideas and research directions for the pathogenesis, prevention, and treatment of other inflammatory-related diseases.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

Macranthoidin B Modulates Key Metabolic Pathways to Enhance ROS Generation and Induce Cytotoxicity and Apoptosis in Colorectal Cancer

Background/Aims: Induction of oxidative stress and reactive oxygen species (ROS) mediated-apoptosis have been utilized as effective strategies in anticancer therapy. Macranthoidin B (MB) is a potent inducer of ROS-mediated apoptosis in cancer, but its mechanism of action is poorly understood. Method: Superoxide production with MB exposure in colorectal cancer (CRC) cells was measured using lucigenin chemiluminescence and real-time PCR. MB’s inhibitory effect on proliferation and viability of CRC cells was determined by proliferation assays. MB’s effect on apoptosis of CRC cells was determined by Western blotting and annexin V-FITC/PI staining. MB’s effect on the growth of CRC xenografts in mice was assessed. An established metabolomics profiling platform combining ultra-performance liquid chromatography-tandem mass spectrometry (LC-MS) with gas chromatography-mass spectrometry (GC-MS) was performed to determine MB’s effect on total metabolite variation in CRC cells. Results: We found that MB increases ROS generation via modulating key metabolic pathways. Using metabolomics profiling platform combining LC-MS with GC-MS, a total of 236 metabolites were identified in HCT-116 cells in which 31 metabolites were determined to be significantly regulated (p ≤ 0.05) after MB exposure. A number of key metabolites revealed by metabolomics analysis include glucose, fructose, citrate, arginine, phenylalanine, and S-adenosylhomocysteine (SAH), suggesting specific modulation of metabolism on carbohydrates, amino acids and peptides, lipids, nucleotide, cofactors and vitamins in HCT-116 CRC cells with MB treatment highly associated with apoptosis triggered by enhanced ROS and activated caspase-3. Conclusion: Our results demonstrate that MB represses CRC cell proliferation by inducing ROS-mediated apoptosis.