Expression profiling and intracellular localization studies of the novel Proline-, Histidine-, and Glycine-rich protein 1 suggest an essential role in gastro-intestinal epithelium and a potential clinical application in colorectal cancer diagnostics.
ABSTRACT: The primary function of the intestines is the absorption of water and nutrients. Although our knowledge about these processes on the cellular level is extensive, a number of important intracellular elements remain unknown. Here, we characterize the novel proline-, histidine-, glycine-rich 1 (PHGR1) mRNA and protein on the molecular level and propose a functional role of the PHGR1 protein in the intestinal and gastric epithelium.PHGR1 mRNA and protein expression in human tissues and cell lines were characterized by quantitative RT-PCR, in situ hybridization, Northern blotting, Western blotting, and immunohistochemistry. Glycosylation was assessed by a chemical deglycosylation assay, whereas intracellular localization was studied by immunofluorescent staining of cell line cells. PHGR1 mRNA levels in HT29 cells was reduced by RNA interference and the resulting global changes in gene expression assessed by microarray hybridization.PHGR1 mRNA and protein were found to be expressed specifically in epithelial cells of intestinal mucosa, with the highest expression in the most mature and differentiated cells. PHGR1 protein was found to be glycosylated and to localize to both the cytoplasm and nucleus. Transcript profiling and gene ontology analysis of HT29 cells subjected to PHGR1 knockdown suggested a functional relationship with transport and metabolic processes. Examination of PHGR1 mRNA and protein levels in lymph nodes with known colorectal cancer metastases indicated that they may serve as biomarkers for detection of such metastases.Functional analyses of the novel PHGR1 mRNA and protein suggest an essential role in gastrointestinal epithelium and a clinical application in detection of colorectal cancer lymph node metastases.
Project description:Little is known regarding the expression or clinical significance of ?-catenin, a member of the catenin family, in colorectal cancer (CRC). The present study examined the expression of ?-catenin using immunohistochemistry in 110 cases of CRC, including 70 cases with complete follow?up records and 40 cases with paired lymph node metastases. In addition, ??catenin mRNA and protein expression were compared in 30 pairs of matched CRC and normal colorectal tissues by reverse transcription quantitative polymerase chain reaction and western blot analysis. ??Catenin was weakly expressed or absent in the cytoplasm of normal intestinal epithelial cells, whereas positive ??catenin expression localized to the cytoplasm was observed in CRC cells. The rate of positive ??catenin expression in CRC (68.18%; 75/110) was significantly higher than that in normal colorectal tissues (36.7%; 11/30; P<0.001). In addition, ??catenin mRNA and protein expression were significantly increased in CRC tissues compared to those in their matched normal tissues (all P<0.05). The expression of ??catenin in stage III?IV CRC was higher than that in stage I?II CRC, and the expression of ??catenin in the tumors of patients with lymph node metastases was higher than that in patients without lymph node metastases. Kaplan?Meier survival curves demonstrated that the survival time of patients with positive ??catenin expression was shorter than that of patients with negative ??catenin expression (P=0.005). Furthermore, Cox multivariate analysis indicated that the tumor, nodes and metastasis stage (P=0.02) and positive ?-catenin expression (P=0.033) were independent prognostic factors in CRC. The present study therefore indicated that ?-catenin may be a suitable independent prognostic factor for CRC.
Project description:L1-cell adhesion molecule (L1CAM, L1) belongs to the immunoglobulin superfamily and was originally found to play a role in nerve cells. Recently, the expression and prognostic value of L1 has been established in several cancers, including colorectal cancer (CRC). However, its association with lymph node metastasis in CRC and the mechanisms underlying its effects remain unclear. In this study, we evaluated the L1 transcript levels in CRC (n=12) and normal intestinal tissues (n=15) by qRT-PCR. Western blotting was used to evaluate L1 and pERK1/2 expression levels. Immunohistochemistry was performed to evaluate the relationship between L1 and pERK1/2 in CRC tissues with different levels of differentiation. The mRNA expression levels in CRC tissues were significantly higher compared to normal intestinal tissues. Western blotting demonstrated that both L1 and pERK1/2 levels were higher in CRC than in normal tissues. Immunohistochemistry confirmed that L1 and pERK1/2 levels in adenomas with lymph node metastasis were significantly higher than in poorly and well-differentiated adenomas, indicating that L1 and pERK1/2 levels correlated with CRC lymph node metastasis. In conclusion, L1 and pERK1/2 were significantly up-regulated in CRC tissues and lymph node metastasis may occur via the L1CAM-mediated ERK pathway in CRC.
Project description:This paper describes some properties of glutamine oxidation and glutaminase isoform expression in cell lines derived from human colorectal adenomas and carcinomas. The slow-growing adenoma-derived cell line AA/C1, and the rapidly proliferating carcinoma cell line HT29, both required glutamine for growth. The rate of (14)CO(2) production from [U-(14)C]glutamine was faster in AA/C1 cells than in HT29 cells. Conversely HT29 cells showed faster rates of glucose oxidation and lactate production. The activity of glutaminase was 3 times higher in AA/C1 cell extracts than in extracts of HT29 cells. Glutaminase activity in the two cell lines had similar K(m) values for glutamine, but the activity in AA/C1 cells had a higher K(0.5) for activation by phosphate. Glutaminase activity in extracts of both cells was inhibited by glutamate. Western blotting showed the presence, in both cell lines, of isoform(s) of glutaminase with an molecular mass of 63 kDa, intermediate between that of kidney glutaminase and liver glutaminase. PCR-based analysis showed that an mRNA species identical to the kidney-type isoform glutaminase C was present in both cell types as was an additional mRNA species identical to the liver-type glutaminase isoform from human breast tumour cells. Northern blotting using isoform-specific cDNA probes demonstrated that mRNA for both glutaminase isoforms was expressed at significant levels in both cell types. Similar results to those in AA/C1 cells and HT29 cells were obtained in two further adenoma and carcinoma cell lines respectively. These results contrast with those reported previously in hepatocyte/hepatoma model systems with respect to fuel selection, glutaminase activity and isoform expression. They also constitute the first demonstration of simultaneous expression of two glutaminase isoforms in a single cell type.
Project description:Keratin (K) intermediate filaments can be divided into type I/type II proteins, which form obligate heteropolymers. Epithelial cells express type I-type II keratin pairs, and K7, K8 (type II) and K18, K19 and K20 (type I) are the primary keratins found in the single-layered intestinal epithelium. Keratins are upregulated during stress in liver, pancreas, lung, kidney and skin, however, little is known about their dynamics in the intestinal stress response. Here, keratin mRNA, protein and phosphorylation levels were studied in response to murine colonic stresses modeling human conditions, and in colorectal cancer HT29 cells. Dextran sulphate sodium (DSS)-colitis was used as a model for intestinal inflammatory stress, which elicited a strong upregulation and widened crypt distribution of K7 and K20. K8 levels were slightly downregulated in acute DSS, while stress-responsive K8 serine-74 phosphorylation (K8 pS74) was increased. By eliminating colonic microflora using antibiotics, K8 pS74 in proliferating cells was significantly increased, together with an upregulation of K8 and K19. In the aging mouse colon, most colonic keratins were upregulated. In vitro, K8, K19 and K8 pS74 levels were increased in response to lipopolysaccharide (LPS)-induced inflammation in HT29 cells. In conclusion, intestinal keratins are differentially and dynamically upregulated and post-translationally modified during stress and recovery.
Project description:Colorectal cancer is the third most prevalent type of cancer in the United States. Early diagnosis of lymph node metastases is essential to improve the prognosis for patients with colorectal cancer. Therefore, the present study aimed to screen genetic markers, including single nucleotide polymorphisms (SNPs), copy number variations (CNVs) and mRNA expression, associated with lymph node metastases in patients with colorectal cancer to enable an early diagnosis. Targeted next-generation sequencing was applied to capture SNPs and CNVs in tumor-related candidate genes within tumor tissues from 39 colorectal cancer patients; reverse transcription-quantitative polymerase chain reaction was used to detect the specific mRNA level of tumor-related candidate genes, including vascular endothelial growth factor C, cyclin-A2, Interleukin-2, ATP-binding cassette sub-family G member 2, epidermal growth factor (EGF) and nuclear factor kappa B subunit 1 (NFKB1) on chromosome 4. The SNPs in solute carrier family 28 member 3 (SLC28A3), breast cancer 1 (BRCA1), ribonucleotide reductase regulators subunit M2 (RRM2), PMS1 homolog 2 (PMS2), cytidine deaminase (CDA), epoxide hydrolase 1 (EPHX1), heterogenous ribonucleoprotein particle-associated with lethal yellow (RALY), Siglec-3 (CD33), B cell lymphoma 10 (BCL10), ETS variant 1 (ETV1), macrophage stimulating 1 receptor 1 (MST1R), lysine methyltransferase 2B (KMT2B), B cell lymphoma 2 (BCL2), U6 small nuclear RNA-associated Sm-like protein 3 (LSM3), thyroid transcription factor 1 (TTF1) and mitogen-activated protein 3 kinase 1 (MAP3K1) were significantly associated with lymphatic metastasis (P<0.05). EGF and NFKB1 were both observed to be significantly downregulated in the lymph node metastases group (P<0.05). Although no association between CNVs and lymph node metastases in patients with colorectal cancer was observed in the present study, SNPs in SLC28A3, BRCA1, RRM2, PMS2, CDA, EPHX1, RALY, CD33, BCL10, ETV1, MST1R, KMT2B, BCL2, LSM3, TTF1 and MAP3K1 were significantly associated with colorectal cancer. Downregulation of EGF and NFKB1 was also identified to be associated with lymph node metastases in colorectal cancer. The findings of the current study provide a scientific basis for the clinical inspection of lymphatic metastasis and prognosis prediction, intervention and guidance therapy for patients with colorectal cancer.
Project description:Lichens produce various unique chemicals that are used in the pharmaceutical industry. To screen for novel lichen secondary metabolites that inhibit the stemness potential of colorectal cancer cells, we tested acetone extracts of 11 lichen samples collected in Chile. Tumidulin, isolated from Niebla sp., reduced spheroid formation in CSC221, DLD1, and HT29 cells. In addition, mRNA expressions and protein levels of cancer stem markers aldehyde dehydrogenase-1 (ALDH1), cluster of differentiation 133 (CD133), CD44, Lgr5, and Musashi-1 were reduced after tumidulin treatment. Tumidulin decreased the transcriptional activity of the glioma-associated oncogene homolog zinc finger protein (Gli) promoter in reporter assays, and western blotting confirmed decreased Gli1, Gli2, and Smoothened (SMO) protein levels. Moreover, the tumidulin activity was not observed in the presence of Gli and SMO inhibitors. Together, these results demonstrate for the first time that tumidulin is a potent inhibitor of colorectal cancer cell stemness.
Project description:This study aimed to explore the application of two radiotracers (18F-fluorodeoxyglucose (FDG) and 18F-fluoromisonidazole (FMISO)) in monitoring hepatic metastases of human colorectal cancer (CRC). Mouse models of CRC hepatic metastases were established by implantation of the human CRC cell lines LoVo and HT29 by intrasplenic injection. Wound healing and Transwell assays were performed to examine cell migration and invasion abilities. Radiotracer-based cellular uptake in vitro and micro-positron emission tomography imaging of liver metastases in vivo were performed. The incidence of liver metastases in LoVo-xenografted mice was significantly higher than that in HT29-xenografted ones. The SUVmax/mean values of 18F-FMISO, but not 18F-FDG, in LoVo xenografts were significantly greater than in HT29 xenografts. In vitro, LoVo cells exhibited stronger metastatic potential and higher radiotracer uptake than HT29 cells. Mechanistically, the expression of HIF-1? and GLUT-1 in LoVo cells and LoVo tumor tissues was remarkably higher than in HT29 cells and tissues. Linear regression analysis demonstrated correlations between cellular 18F-FDG/18F-FMISO uptake and HIF-1?/GLUT-1 expression in vitro, as well as between 18F-FMISO SUVmax and GLUT-1 expression in vivo. 18F-FMISO uptake may serve as a potential biomarker for the detection of liver metastases in CRC, whereas its clinical use warrants validation.
Project description:Background:Our previous studies revealed that Jagged 2 (JAG2) is involved in the regulation of migration and invasion of colon cancer cells without affecting cell proliferation. This study further explored the specific mechanism by which JAG2 promotes migration and invasion of colorectal cancer cells. Methods:JAG2 mRNA expression in different clinical stages of colorectal cancer and normal intestinal tissues was detected by quantitative PCR (QPCR). QPCR and Western Blot were used to analyze the differential expression of JAG2 mRNA and protein between normal human colon tissue cells and various colorectal cancer cells. Co-expression status of JAG2 and epithelial-mesenchymal transition (EMT) markers in colon cancer tissues and cells was analyzed. The difference between TGF-?-induced EMT model and the JAG2 overexpression model were compared in promoting migration and invasion of HT29 cells. HT29 cells were treated with EMT pathway inhibitors (LY2157299 and Slug siRNA) to identify a cross-talk between the JAG2 effect and the Notch pathway. Co-expressed genes of JAG2 in colorectal cancer cells were identified using siRNA and transcriptome microarray technology. The mutual regulation of JAG2 and the co-expressed gene PRAF2 and the regulation of the paracrine effect of exosomes were analyzed. Results:JAG2 was abnormally expressed in colorectal cancer tissues and directly related to clinical stages. Similar to the findings in tissues, the expression of both JAG2 mRNA and protein was significantly increased in the colorectal cancer cell lines compared with that of normal colorectal cell line CCD18-Co. It was shown in our cell model that JAG2 was involved in the regulation of migration and invasion independent of the canonical Notch signaling pathway. More interestingly, JAG2 also promoted the migration and invasion of colon cancer cells in a non-EMT pathway. Further analysis revealed the co-expression of JAG2 with PRAF2 in colorectal cancer cells. JAG2-rich exosomes were released from colorectal cancer cells in a PRAF2-dependent way, while these exosomes regulated the metastasis of colorectal cancer cells in a paracrine manner. Conclusions:This is the evidence supporting the biological function of JAG2 through non-canonical Notch and non-EMT-dependent pathways and also the first demonstration of the functions of PRAF2 in colorectal cancer cells. These findings also provide theoretical basis for the development of small molecules or biological agents for therapeutic intervention targeting JAG2/PRAF2.
Project description:Although deregulation of EPHB signaling has been shown to be an important step in colorectal tumorigenesis, the role of EPHB6 in this process has not been investigated. We found here that manipulation of EPHB6 levels in colon cancer cell lines has no effect on their motility and growth on a solid substrate, soft agar or in a xenograft mouse model. We then used an EphB6 knockout mouse model to show that EphB6 inactivation does not efficiently initiate tumorigenesis in the intestinal tract. In addition, when intestinal tumors are initiated genetically or pharmacologically in EphB6+/+ and EphB6-/- mice, no differences were observed in animal survival, tumor multiplicity, size or histology, and proliferation of intestinal epithelial cells or tumor cells. However, reintroduction of EPHB6 into colon cancer cells significantly reduced the number of lung metastasis after tail-vein injection in immunodeficient mice, while EPHB6 knockdown in EPHB6-expressing cells increased their metastatic spread. Consistently, although EPHB6 protein expression in a series of 130 primary colorectal tumors was not associated with patient survival, EPHB6 expression was significantly lower in lymph node metastases compared to primary tumors. Our results indicate that the loss of EPHB6 contributes to the metastatic process of colorectal cancer.
Project description:To explore the possible misexpression of the microRNA miR-196b in colorectal cancer (CRC) and its role in controlling the expression of GATA6, a putative target gene crucial to intestinal cell homeostasis and tumorigenesis.The expression of miR-196b was analysed by qRT-PCR in surgical resection samples from a cohort of sporadic colon cancer patients. Manipulations of miR-196b expression were performed to demonstrate its inhibition of GATA6 protein levels.We found that miR-196b is significantly upregulated in pre-treatment surgical resection samples from a cohort of sporadic colon cancer patients. The upregulation of miR-196b correlates with less severe clinicopathological characteristics, such as early tumor stage and absence of lymph node metastases. We show that in CRC cells, miR-196b targets the mRNA of GATA6, a transcription factor involved in the homeostasis and differentiation of intestinal epithelial cells, and a positive regulator of the Wnt/?-catenin pathway. We moreover found that the increase of miR-196b correlates with a reduced GATA6 protein expression in colon cancer patients.Our results establish miR-196b as a post-transcriptional inhibitor of GATA6 in CRC cells, implicating miR-196b function in gene regulatory pathways crucial to intestinal cell homeostasis and tumorigenesis. Our results furthermore suggest a role of miR-196b expression in CRC, as an antagonist of GATA6 function in tumor cells, thus providing the basis for a potential targeting strategy for the treatment of CRC.