Effect of glucose availability on glucose transport in bovine mammary epithelial cells

Primary bovine mammary epithelial cells (BMEC) were cultured in media containing varying concentrations of glucose, to determine the effects of glucose availability on glucose transport and its mechanism in bovine mammary gland. The BMEC incubated with 10 and 20 mM glucose had twofold greater glucose uptake than that with 2.5 mM glucose (P < 0.05). Increased glucose availability enhanced the cell proliferation (P < 0.05). As the glucose uptake is mediated by facilitative glucose transporters (GLUTs), the expression of GLUT mRNA was investigated. Compared with the control (2.5 mM), 5 and 10 mM glucose did not influence the abundance of GLUT1 mRNA (P < 0.05), whereas 20 mM glucose decreased the GLUT1 mRNA expression in the BMEC (P < 0.05). The expression of GLUT8 mRNA was not affected by any concentration of glucose (P > 0.05). As GLUTs are coupled with hexokinases (HKs) in regulating glucose uptake, the expression of HKs and their activities were also studied. The HK activity was greater in 5, 10 and 20 mM glucose than that in 2.5 mM glucose (P < 0.05). The expression of HK2 mRNA rather than HK1 mRNA was detected in the BMEC; however, the abundance of HK2 mRNA was not elevated by any concentrations of glucose compared with control (P > 0.05). Furthermore, addition of 3-bromopyruvate (30, 50 or 70 μM), an inhibitor of HK2, resulted in the decrease of glucose uptake and cell proliferation at both 2.5 and 10 mM glucose (P < 0.05). Therefore, the glucose concentrations may affect glucose uptake partly by altering the activity of HKs, and HK2 may play an important role in the regulation of glucose uptake in the BMEC.     

SLC1A3 promotes gastric cancer progression via the PI3K/AKT signalling pathway

Gastric cancer is a major cause of mortality worldwide. The glutamate/aspartate transporter SLC1A3 has been implicated in tumour metabolism and progression, but the roles of SLC1A3 in gastric cancer remain unclear. We used bioinformatics approaches to analyse the expression of SLC1A3 and its role in gastric cancer. The expression levels of SLC1A3 were examined using RT‐qPCR and Western bolting. SLC1A3 overexpressing and knock‐down cell lines were constructed, and the cell viability was evaluated. Glucose consumption, lactate excretion and ATP levels were determined. The roles of SLC1A3 in tumour growth were evaluated using a xenograft tumour growth model. SLC1A3 was found to be overexpressed in gastric cancer, and this overexpression was associated with poor prognosis. In vitro and in vivo assays showed that SLC1A3 affected glucose metabolism and promoted gastric cancer growth. GSEA analysis suggested that SLC1A3 was positively associated with the up‐regulation of the PI3K/AKT pathway. SLC1A3 overexpression activated the PI3K/AKT pathway and up‐regulated GLUT1, HK II and LDHA expression. The PI3K/AKT inhibitor LY294002 prevented SLC1A3‐induced glucose metabolism and cell proliferation. Our findings indicate that SLC1A3 promotes gastric cancer progression via the PI3K/AKT signalling pathway. SLC1A3 is therefore a potential therapeutic target in gastric cancer.     

Wnt1-inducible signaling protein 1 regulates laryngeal squamous cell carcinoma glycolysis and chemoresistance via the YAP1/TEAD1/GLUT1 pathway

Wnt1-inducible signaling protein 1 (WISP1) is a matricellular protein and downstream target of Wnt/β-catenin signaling. This study sought to determine the role of WISP1 in glucose metabolism and chemoresistance in laryngeal squamous cell carcinoma. WISP1 expression was silenced or upregulated in Hep-2 cells by the transfection of WISP1 siRNA or AdWISP1 vector. Ectopic WISP1 expression regulated glucose uptake and lactate production in Hep-2 cells. Subsequently, the expression of glucose transporter 1 (GLUT1) was significantly modulated by WISP1. Furthermore, WISP1 increased cell survival rates, diminished cell death rates, and suppressed ataxia-telangiectasia-mutated (ATM)-mediated DNA damage response pathway in cancer cells treated with cisplatin through GLUT1. WISP1 also promoted cancer cell tumorigenicity and growth in mice implanted with Hep-2 cells. Additionally, WISP1 activated the YAP1/TEAD1 pathway that consequently contributed to the regulation of GLUT1 expression. In summary, WISP1 regulated glucose metabolism and cisplatin resistance in laryngeal cancer by regulating GLUT1 expression. WISP1 may be used as a potential therapeutic target for laryngeal cancer.     

Glucose promotes epithelial‐mesenchymal transitions in bladder cancer by regulating the functions of YAP1 and TAZ

Glucose levels and type 2 diabetes (T2D) are both associated with tumorigenesis and epithelial‐mesenchymal transitions (EMTs). EMTs facilitate bladder cancer (BC) metastasis development, but the mechanism by which high‐glucose levels promote these EMTs in BC remains unclear. Therefore, we sought to elucidate the mechanism underlying EMT promotion due to increased glucose levels. T24 and UMUC‐3 cells were cultured in media containing different glucose concentrations. YAP1, TAZ, GLUT1 and EMT‐associated marker expression was analysed via Western blotting and qPCR. BC cell proliferation and invasion were assessed using MTT and Transwell assays, respectively. A xenograft nude mouse model of diabetes was used to evaluate tumour growth and metastasis in vivo. T2D was positively associated with pathologic grade (P = .016) and TNM stage (P < .001) in BC. High glucose triggered BC cell proliferation and invasion in both in vitro and in vivo conditions. High‐glucose levels also promoted EMTs in BC cells and increased YAP1 and TAZ expression. YAP1 or TAZ knockdown altered EMT marker expression and decreased GLUT1 expression. Overall, our results suggest that high‐glucose levels promote EMTs in BC cells via YAP1 and TAZ regulation. These effector molecules may be promising therapeutic targets for BC cases comorbid with T2D.     

MicroRNA-150 Predicts a Favorable Prognosis in Patients with Epithelial Ovarian Cancer,and Inhibits Cell Invasion and Metastasis by Suppressing Transcriptional Repressor ZEB1

MicroRNA (miR)-150 has been reported to be dramatically downregulated in human epithelial ovarian cancer (EOC) tissues and patients’ serum compared to normal controls. This study aimed to investigate clinical significance and molecular mechanisms of miR-150 in EOC. In the current study, quantitative real-time PCR analysis showed that miR-150 was significantly downregulated in human EOC tissues compared to normal tissue samples. Then, we demonstrated the significant associations of miR-150 downregulation with aggressive clinicopathological features of EOC patients, including high clinical stage and pathological grade, and shorter overall and progression-free survivals. More importantly, the multivariate analysis identified miR-150 expression as an independent prognostic biomarker in EOC. After that, luciferase reporter assays demonstrated that Zinc Finger E-Box Binding Homeobox 1 (ZEB1), a crucial regulator of epithelial-to-mesenchymal transition (EMT), was a direct target of miR-150 in EOC cells. Moreover, we found that the ectopic expression of miR-150 could efficiently inhibit cell proliferation, invasion and metastasis by suppressing the expression of ZEB1. Furthermore, we also observed a significantly negative correlation between miR-150 and ZEB1 mRNA expression in EOC tissues (rs = –0.45, P<0.001). In conclusion, these findings offer the convincing evidence that aberrant expression of miR-150 may play a role in tumor progression and prognosis in patients with EOC. Moreover, our data reveal that miR-150 may function as a tumor suppressor and modulate EOC cell proliferation, and invasion by directly and negatively regulating ZEB1, implying the re-expression of miR-150 might be a potential therapeutic strategy for EOC.     

Circle RNA hsa_circRNA_100290 serves as a ceRNA for miR-378a to regulate oral squamous cell carcinoma cells growth via Glucose transporter-1 (GLUT1) and glycolysis

Aerobic glycolysis (the Warburg effect) is a robust metabolic hallmark of most tumors, including oral squamous cell carcinoma (OSCC). Glucose transporter 1 (GLUT1), a major glucose transporter regulating the glucose uptake, is upregulated in OSCC and participated in the cell glycolysis of OSCC. The deregulation and function of noncoding RNAs in cancers have been widely reported. Reportedly, hsa_circular RNA (circRNA)_100290 (circ_SLC30A7) is significantly upregulated (fold change = 6.91, p < 0.0000001) in OSCC. According to online tools prediction (miRWalk, miRanda, and Targetscan), miR-378a could simultaneously target circRNA_100290 and GLUT1. Herein, the expression of circRNA_100290 and GLUT1 remarkably increased in oral tumor tissue specimens and cells. In OSCC cell lines, cell proliferation and glycolysis could be remarkably downregulated by circRNA_100290 silence, which could be rescued by GLUT1 overexpression. Conversely, miR-378a expression could be remarkably inhibited in tumor tissue specimens and cells. The effect of miR-378a overexpression on OSCC cells was similar to those of circRNA_100290 silence. miR-378a directly bound to circRNA_100290 and GLUT1 3′-untranslated region, circRNA_100290 could remarkably relieve miR-378a-induced inhibition on GLUT1 via acting as a competing endogenous RNA (ceRNA). miR-378a inhibition remarkably attenuated the effect of circRNA_100290 silence on cell proliferation and glycolysis in OSCC cell lines. In summary, circRNA_100290 serves as a ceRNA to counteract miR-378a-mediated GLUT1 suppression, thus promoting glycolysis and cell proliferation in OSCC. We provide a reliable experimental basis for understanding the mechanism of cell growth and glycolysis deregulation in OSCC.     

TBK1 Facilitates GLUT1-Dependent Glucose Consumption by suppressing mTORC1 Signaling in Colorectal Cancer Progression

Intestinal inflammation is a vital precipitating factor of colorectal cancer (CRC), but the underlying mechanisms are still elusive. TANK-binding kinase 1 (TBK1) is a core enzyme downstream of several inflammatory signals. Recent studies brought the impacts of TBK1 in malignant disease to the forefront, we found aberrant TBK1 expression in CRC is correlated with CRC progression. TBK1 inhibition impaired CRC cell proliferation, migration, drug resistance and tumor growth. Bioinformatic analysis and experiments in vitro showed overexpressed TBK1 inhibited mTORC1 signaling activation in CRC along with elevated GLUT1 expression without inducing GLUT1 translation. TBK1 mediated mTORC1 inhibition induces intracellular autophagy, which in turn decreasing GLUT1 degradation. As a rescue, blocking of autophagosome and retromer respectively via autophagy-related gene 7 (ATG7) or TBC1 Domain Family Member 5 (TBC1D5) silence diminished the regulation of TBK1 to GLUT1. GLUT1 staining presented that TBK1 facilitated GLUT1 membrane translocation which subsequently enhanced glucose consumption. Inhibitor of TBK1 also decreased GLUT1 expression which potentiated drug-sensitivity of CRC cell. Collectively, TBK1 facilitates glucose consumption for supporting CRC progression via initiating mTORC1 inhibition induced autophagy which decreases GLUT1 degradation and increases GLUT1 membrane location. The adaptive signaling cascade between TBK1 and GLUT1 proposes a new strategy for CRC therapy.     

In Silico Modeling-based Identification of Glucose Transporter 4 (GLUT4)-selective Inhibitors for Cancer Therapy

Tumor cells rely on elevated glucose consumption and metabolism for survival and proliferation. Glucose transporters mediating glucose entry are key proximal rate-limiting checkpoints. Unlike GLUT1 that is highly expressed in cancer and more ubiquitously expressed in normal tissues, GLUT4 exhibits more limited normal expression profiles. We have previously determined that insulin-responsive GLUT4 is constitutively localized on the plasma membrane of myeloma cells. Consequently, suppression of GLUT4 or inhibition of glucose transport with the HIV protease inhibitor ritonavir elicited growth arrest and/or apoptosis in multiple myeloma. GLUT4 inhibition also caused sensitization to metformin in multiple myeloma and chronic lymphocytic leukemia and a number of solid tumors suggesting the broader therapeutic utility of targeting GLUT4. This study sought to identify selective inhibitors of GLUT4 to develop a more potent cancer chemotherapeutic with fewer potential off-target effects. Recently, the crystal structure of GLUT1 in an inward open conformation was reported. Although this is an important achievement, a full understanding of the structural biology of facilitative glucose transport remains elusive. To date, there is no three-dimensional structure for GLUT4. We have generated a homology model for GLUT4 that we utilized to screen for drug-like compounds from a library of 18 million compounds. Despite 68% homology between GLUT1 and GLUT4, our virtual screen identified two potent compounds that were shown to target GLUT4 preferentially over GLUT1 and block glucose transport. Our results strongly bolster the utility of developing GLUT4-selective inhibitors as anti-cancer therapeutics.     

Insulin regulates GLUT1-mediated glucose transport in MG-63 human osteosarcoma cells

Osteosarcoma is the most common type of malignant bone cancer, accounting for 35% of primary bone malignancies. Because cancer cells utilize glucose as their primary energy substrate, the expression and regulation of glucose transporters (GLUT) may be important in tumor development and progression. GLUT expression has not been studied previously in human osteosarcoma cell lines. Furthermore, although insulin and insulin-like growth factor (IGF-I) play an important role in cell proliferation and tumor progression, the role of these hormones on GLUT expression and glucose uptake, and their possible relation to osteosarcoma, have also not been studied. We determined the effect of insulin and IGF-I on GLUT expression and glucose transport in three well-characterized human osteosarcoma cell lines (MG-63, SaOs-2, and U2-Os) using immunocytochemical, RT-PCR and functional kinetic analyses. Furthermore we also studied GLUT isoform expression in osteosarcoma primary tumors and metastases by in situ hybridization and immunohistochemical analyses. RT-PCR and immunostaining show that GLUT1 is the main isoform expressed in the cell lines and tissues studied, respectively. Immunocytochemical analysis shows that although insulin does not affect levels of GLUT1 expression it does induce a translocation of the transporter to the plasma membrane. This translocation is associated with increased transport of glucose into the cell. GLUT1 is the main glucose transporter expressed in osteosarcoma, furthermore, this transporter is regulated by insulin in human MG-63 cells. One possible mechanism through which insulin is involved in cancer progression is by increasing the amount of glucose available to the cancer cell.     

Novel evidence for oncogenic piRNA‐823 as a promising prognostic biomarker and a potential therapeutic target in colorectal cancer

piRNA‐823 as a member of the piRNA family is reported to promote tumour cell proliferation in multiple myeloma and hepatocellular cancer. However, few studies on the function of piRNA‐823 in colorectal cancer (CRC). Our present study data showed that piRNA‐823 plays an oncogene role in CRC cells. Inhibition of piRNA‐823 can significantly inhibit the proliferation, invasion and apoptosis resistance of CRC cells. Mechanism studies have shown that piRNA‐823 inhibits the ubiquitination of hypoxia‐inducible factor‐1 alpha (HIF‐1α) by up‐regulating the expression of Glucose‐6‐phosphate dehydrogenase (G6PD) and ultimately up‐regulates the glucose consumption of carcinoma cells and inhibits the content of intracellular reactive oxygen species (ROS). Therefore, we speculate piRNA‐823 promotes the proliferation, invasion and apoptosis resistance of CRC cells by regulating G6PD/HIF‐1α pathway. In this study, we set up the cancer‐promoting function recovery experiment of piRNA‐823 by silencing G6PD gene to confirm the dominance of the above‐mentioned pathways. Using clinical samples, we found that overexpression of piRNA‐823 correlated with poor overall survival and predicted a poor response to adjuvant chemotherapy of patients with CRC. In a word, our research has further enriched the theory of piRNA‐823 promoting the progression of CRC, and laid a solid foundation for the development of piRNA‐823‐based gene therapy for CRC and its use as a promising prognostic biomarker in CRC patients.     

Differential metabolic adaptation to acute and long-term hypoxia in rat primary cortical astrocytes

Brain astrocytes provide structural and metabolic support to surrounding cells during ischemia. Glucose and oxygen are critical to brain function, and glucose uptake and metabolism by astrocytes are essential to their metabolic coupling to neurons. To examine astrocyte metabolic response to hypoxia, cell survival and metabolic parameters were assessed in rat primary cortical astrocytes cultured for 3 weeks in either normoxia or in either 1 day or 3 weeks sustained hypoxia (5% O2). Although cell survival and proliferation were not affected by the mildly hypoxic environment, substantial differences in glucose consumption and lactate release after either acute or prolonged hypoxia suggest that astrocyte metabolism may contribute to their adaptation. Hypoxia over a period of 1 day increased glucose uptake, lactate release, and glucose transporter 1 (GLUT1) and monocarboxylate transporter 1 (MCT1) expression, whereas hypoxia over a period of 3 weeks resulted in a decrease of all parameters. Furthermore, increased glucose uptake at 1 day of hypoxia was not inhibited by cytochalasin B suggesting the involvement of additional glucose transporters. We uncovered hypoxia-regulated expression of sodium-dependent glucose transporters (SGLT1) in astrocytes indicating a novel adaptive strategy involving both SGLT1 and GLUT1 to regulate glucose intake in response to hypoxia. Overall, these findings suggest that although increased metabolic response is required for the onset of astrocyte adaptation to hypoxia, prolonged hypoxia requires a shift to an energy conservation mode. These findings may contribute to the understanding of the relative tolerance of astrocytes to hypoxia compared with neurons and provide novel therapeutic strategies aimed at maintaining brain function in cerebral pathologies involving hypoxia.     

Glycogen overload by postexercise insulin administration abolished the exercise-induced increase in GLUT4 protein

Summary To elucidate the role of muscle glycogen storage on regulation of GLUT4 protein expression and whole-body glucose tolerance, muscle glycogen level was manipulated by exercise and insulin administration. Sixty Sprague-Dawley rats were evenly separated into three groups: control (CON), immediately after exercise (EX0), and 16 h after exercise (EX16). Rats from each group were further divided into two groups: saline- and insulin-injected. The 2-day exercise protocol consisted of 2 bouts of 3-h swimming with 45-min rest for each day, which effectively depleted glycogen in both red gastrocnemius (RG) and plantaris muscles. EX0 rats were sacrificed immediately after the last bout of exercise on second day. CON and EX16 rats were intubated with 1 g/kg glucose solution following exercise and recovery for 16 h before muscle tissue collection. Insulin (0.5 μU/kg) or saline was injected daily at the time when glucose was intubated. Insulin injection elevated muscle glycogen levels substantially in both muscles above saline-injected group at CON and EX16. With previous day insulin injection, EX0 preserved greater amount of postexercise glycogen above their saline-injected control. In the saline-injected rats, EX16 significantly increased GLUT4 protein level above CON, concurrent with muscle glycogen supercompensation. Insulin injection for EX16 rats significantly enhanced muscle glycogen level above their saline-injected control, but the increases in muscle GLUT4 protein and whole-body glucose tolerance were attenuated. In conclusion, the new finding of the study was that glycogen overload by postexercise insulin administration significantly abolished the exercise-induced increases in GLUT4 protein and glucose tolerance.     

TMEM207 hinders the tumour suppressor function of WWOX in oral squamous cell carcinoma

The WW domain‐containing oxidoreductase (WWOX) functions as a tumour suppressor in oral carcinogenesis. As aberrant TMEM207 expression may lead to tumour progression by hampering the tumour suppressor function of WWOX in various cancers, we explored the expression and pathobiological properties of TMEM207, focusing on the WWOX‐mediated regulation of the HIF‐1α pathway in oral squamous cell carcinoma (OSCC). TMEM207 immunoreactivity was detected in 40 of 90 OSCC samples but not in neighbouring non‐tumorous epithelial tissues. Moreover, TMEM207 expression was significantly correlated with lymph node metastasis and poor prognosis. An in situ proximal ligation assay demonstrated the colocalization of TMEM207 and WWOX in invasive OSCC cells, especially glycogen‐rich ones. Enforced expression of TMEM207 abrogated the binding of WWOX to HIF‐1α, increased HIF‐1α and GLUT‐1 expression, even under normoxic conditions, and promoted tumour growth in a xenoplant assay using SAS tongue squamous cancer cells. In contrast, TMEM207 knockdown decreased GLUT‐1 expression in two OSCC cell lines. As a whole, our findings indicate that the aberrant expression of TMEM207 contributes to tumour progression in OSCC, possibly via promoting aerobic glycolysis.     

Growth factors, mitogens, oncogenes and the regulation of glucose transport

The erythrocyte (or HepG2/brain) type glucose transporter (GLUT 1) was the first of the family of facilitative glucose transporter proteins to be cloned [M. Mueckler et al., Science 229, 941–945, 1985]. GLUT 1 is expressed in most tissue types, all cells lines, transformed cells and tumour cells. It is thought to be responsible for ‘housekeeping’ levels of glucose transport, i.e. the uptake of glucose required for oxidative phosphorylation. The rate of glucose transport via GLUT 1 can be regulated under conditions in which the metabolic rate must be adjusted such as cell division (mitosis and meiosis), differentiation, transformation and nutrient starvation. Here we review the recent literature on the control of glucose transport of mitogens, growth factors and oncogenes, and discuss some of the implications for the integration of cellular signalling pathways and cell growth.     

Axed MUC4 (MUC4/X) aggravates pancreatic malignant phenotype by activating integrin-β1/FAK/ERK pathway

Alternative splicing is evolving as an eminent player of oncogenic signaling for tumor development and progression. Mucin 4 (MUC4), a type I membrane-bound mucin, is differentially expressed in pancreatic cancer (PC) and plays a critical role in its progression and metastasis. However, the molecular implications of MUC4 splice variants during disease pathogenesis remain obscure. The present study delineates the pathological and molecular significance of a unique splice variant of MUC4, MUC4/X, which lacks the largest exon 2, along with exon 3. Exon 2 encodes for the highly glycosylated tandem repeat (TR) domain of MUC4 and its absence creates MUC4/X, which is devoid of TR. Expression analysis from PC clinical samples revealed significant upregulation of MUC4/X in PC tissues with most differential expression in poorly differentiated tumors. In vitro studies suggest that overexpression of MUC4/X in wild-type-MUC4 (WT-MUC4) null PC cell lines markedly enhanced PC cell proliferation, invasion, and adhesion to extracellular matrix (ECM) proteins. Furthermore, MUC4/X overexpression leads to an increase in the tumorigenic potential of PC cells in orthotopic transplantation studies. In line with these findings, doxycycline-induced expression of MUC4/X in an endogenous WT-MUC4 expressing PC cell line (Capan-1) also displayed enhanced cell proliferation, invasion, and adhesion to ECM, compared to WT-MUC4 alone, emphasizing its direct involvement in the aggressive behavior of PC cells. Investigation into the molecular mechanism suggested that MUC4/X facilitated PC tumorigenesis via integrin-β1/FAK/ERK signaling pathway. Overall, these findings revealed the novel role of MUC4/X in promoting and sustaining the oncogenic features of PC.     

Tumour-suppressive microRNA-424-5p directly targets CCNE1 as potential prognostic markers in epithelial ovarian cancer

An accumulated evidence supports that MicroRNAs (miRNAs) have shown a prominent role in pathological processes and different tumor onset. However, to date, the potential functional roles and molecular mechanisms by how microRNA-424-5p(miR-424-5p) affects cancer cell proliferation are greatly unclear, especially in epithelial ovarian cancer(EOC).In this study, we demonstrated that miR-424-5p was significantly down-regulated in EOC tissues and cell lines. The level of miR-424-5p was negatively correlated with tumor size, TNM stage, pathological grade, lymphatic metastasis of EOC. Restoring miR-424-5p expression in EOC cells dramatically suppressed cell proliferation and caused an accumulation of cells in G1 phase, and thus contributed to better prognosis of EOC patients. Mechanistically, miR-424-5p inhibits CCNE1 expression through targeting CCNE1 3′UTR, and subsequent arrest cell cycle in G1/G0 phase by inhibiting E2F1-pRb pathway. This study revealed functional and mechanistic links between miR-424-5p and CCNE1 in the progression of EOC and provide an important insight into that miR-424-5p may serve as a therapeutic target in EOC.     

Sialylation regulates galectin-3/ligand interplay during mammary tumour progression--a case of targeted uncloaking

Galectin-3 is involved both in facilitating detachment of cells from primary tumour sites and favouring cancer cell adhesion and survival to anoikis in the blood stream. The mechanisms behind these apparently contradictory roles of the lectin have not yet been resolved. In order to investigate possible interplays between galectin-3 and its ligands underlying their role in the metastatic process, we examined mucin-1 (MUC1) and epidermal growth factor receptor (EGFR), well-known galectin-3 ligands, as well as galectin-3-binding site expression in a series of spontaneous canine malignant mammary tumours (CMMT) and a metastatic CMMT cell line. Despite the fact that CMMT cells expressed MUC1 and EGFR homogeneously over their plasma membrane, intravascular tumour cells, positive for galectin-3, expressed MUC1 and EGFR in a more focal membrane localization. Moreover, MUC1 overexpression in primary CMMT was present in parallel with down-regulation of galectin-3. Furthermore, in the CMT-U27 cell line, galectin-3 knock-down led to increased MUC1 expression, while MUC1 knock-down led to down-regulation of the lectin. Finally, removal of sialic acid from both CMMT and CMT-U27 xenograft samples exposed galectin-3-ligands throughout the tumour tissue, whereas these ligands were only present in galectin-3-positive invading cells in untreated samples. Interestingly indeed, we show that in vessel-invading cells, there is interaction between galectin-3 and the T antigen in vivo. We therefore hypothesized that loss of galectin-3 and sialylation-related masking of its ligands, in conjunction with their overexpression in specific tumour cell subpopulations, are crucial in regulating adhesive/de-adhesive events in the progression and invasive capacity of metastatic cells.