Expression of Nucleophosmin/NPM1 correlates with migration and invasiveness of colon cancer cells
© Liu et al.; licensee BioMed Central Ltd. 2012
Received: 8 January 2012
Accepted: 25 May 2012
Published: 25 May 2012
We aimed to examine the expression level of Nucleophosmin (NPM1) protein in colon cancer tissues and to investigate the potential role of NPM1 in the regulation of cell migration and invasiveness.
Immunohistochemical assay was performed to examine the expression pattern of NPM1 in 31 groups of colonic carcinoma samples, including colon tumors, adjacent normal tissues, and matched metastatic lymph nodes from the same patients. Small interfering RNA technique and exogenous expression of wild type NPM1 methods were used to further verify the function of NPM1.
High-expression of NPM1 correlates with lymph node metastasis (P = 0.0003) and poor survival rate of human colon cancer patients (P = 0.017). SiRNA-mediated reduction of NPM1 was also shown to inhibit the migration and invasiveness of metastatic colon cancer HCT116 cell line. In addition, the exogenous expression of NPM1 in HT29 cells, a NPM1 low expression and low invasive colon cancer cell line, enhanced cell migration and invasiveness along with increased cell proliferation.
The current study uncovered the critical role of NPM1 in the regulation of colon cancer cells migration and invasion, and NPM1 may serve as a potential marker for the prognosis of colon cancer patients.
KeywordsHuman colon cancer Nucleophosmin (NPM1) Invasion Migration
The incidence of colon cancer in China has increased in recent years and has become one of the most common malignancies, particularly in more developed areas . Surgery and chemotherapy are highly effective for early-stage colon cancer . However, the five-year survival rate of advanced colon cancer patients was very poor because of insensitivity to chemotherapy and more easily prone to recurrence . Thus, the majority of patients with advanced-stage colon cancer die of metastasis. Molecular-targeted therapy has developed recently as a more effective approach for the treatment of metastatic colon cancer patients. However, whether the patients could receive the targeted drug therapy depends on the molecular profile of their cancer tissues. Until now, only a few effective targeted drugs are available for targeted therapy, such as bevacizumab, which binds to VEGF and inhibits the initiation of new blood vessel growth , and cetuximab, which targets EGFR and prevents the activation of cell growth signaling . Screening and understanding novel genes involved in carcinogenesis or cancer metastasis is urgently needed to identify putative molecular targets for cancer therapy.
NPM1 is also called nucleophosmin, numatrin  or NO38 . It consists of 294 amino acids. NPM1 is an abundant multifunctional nucleolar phosphoprotein, which shuttles constantly between the nucleus and cytoplasm and is involved in several important biological activities . Previous studies demonstrated a critical role of NPM1 in ribosome biogenesis by regulating ribosome assembly and transporting ribosomal proteins to the cytoplasm. NPM1 also plays an essential role in cell growth and proliferation by regulating cell cycle progression and centrosome duplication [9, 10]. Other studies also showed that NPM1 could regulate the activity of several tumor suppressors, including P53 and Rb by direct binding . NPM1 is also involved in transcription activation through interaction with transcription factors, such as c-Myc and NF-κB . In addition, NPM1 also functions as a molecular chaperone to regulate DNA histone assembly and proper folding of unfolding proteins .
Numerous studies revealed a critical role of NPM1 in tumorigenesis . Altered NPM1 expression was observed in many types of tumors, and mutated NPM1 is frequently detected in human hematopoietic malignancies, especially in acute myeloid leukemia (AML) . Recent research demonstrated that NPM1 may be a favorable prognosis marker for AML and even a potential therapeutic target in hematological malignances . In contrast to AML, mutations of NPM1 are rarely detected in solid tumors. However, over-expression of NPM1 is often found in many kinds of solid tumors [17, 18]. Accumulative evidence suggested that highly expressed NPM1 correlated with the stage of tumor progression and poor prognosis . Although the function of NPM1 in carcinogenesis has been intensively studied, the detailed mechanism is largely unknown.
In the current study, the expression pattern of NPM1 in colon cancer tissues and adjacent normal tissues was examined. Increased expression of NPM1 was also found to be associated with lymph node metastasis and poor survival of colon cancer patients. The current study hypothesized that NPM1 may play a role in cancer cell migration and invasion. Small interfering RNA (siRNA) induced the down-regulation of NPM1-inhibited migration and invasiveness of metastatic colon cancer in the HCT116 cell line. Furthermore, exogenous expression of wild-type NPM1 in HT29 cells enhanced cell migration and invasiveness along with increased cell proliferation. These results revealed that NPM1 serves as an important regulator for cancer cell invasion.
Cancer tissues and immunohistochemistry
Colon cancer tissues, adjacent normal tissues, and matched metastatic lymph nodes were obtained from patients diagnosed with colon cancer in Tianjin Medical University Cancer Institute and Hospital (Tianjin, P. R. China) between 2000 and 2005. Immunohistochemical assay was performed as described previously . In brief, tissue slides were deparaffinized in xylene and rehydrated with graded ethanol. The slides were heat induced in sodium citrate buffer for antigen retrieval, blocked in 3% BSA for 40 min, and incubated with mouse anti-human NPM1 antibodies (Santa Cruz Biotechnology, CA, USA) (1:50) at 4°C overnight. Detection was performed using an HRP-linked secondary antibody and a DAB kit. The slides were then counterstained with hematoxylin and mounted. Highly expressed NPM1 in human breast cancer tissue was used as a positive control. A negative control was prepared by omitting the primary antibody. The staining intensity and percentage of positive cells were scored semi-quantitatively by two pathology doctors. The intensity of staining was classified into four categories: "0" for no brown particle staining, "1" for light brown particles, "2" for moderate brown particles, and "3" for dark brown particles. The percentage of positive cells was divided into four groups: "0" for <10% positive cells, "1" for 10%–40% positive cells, "2" for 40%–70% positive cells, and "3" for ≥70% positive cells. The sum of the intensity and percentage of positive staining was used to determine high (score ≥ 3) or low (score < 3) expression of NPM1.
Human colon cancer cell lines HCT116 and HT29 was purchased from Cell Resource Center, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences/Peking Union Medical College (Beijing, China). HCT116 cells were maintained in Iscove’s Modified Dulbecco’s medium (IMDM) (Hyclone, USA) supplemented with 10% fetal bovine serum (FBS, Hyclone, USA), HT29, SW480, Colo205 and SW620 cells were cultured in Dulbecco's Modified Eagle Medium supplemented with 10% FBS and 100U of penicillin and streptomycin (Hyclone, USA).
Plasmid construction, siRNA and plasmid transfection
NPM1 specific siRNA (Sense: 5' -CCUAGUUCUGUAGAAGACAtt-3' and Antisense: 5' -ttUGUCUUCUACAGAACUAGGsiRNA-3') was synthesized by Genechem Co (Shanghai, P. R. China). Full length NPM1 was amplified by PCR with the followed primers: Forward: 5'-GCGCTCGAGATGGAAGATTCGATGGACATG-3'reverse: 5'-CGCGAATTCAAGAGACTTCCTCCACTG-3'. The PCR products were purified, digested and cloned into pEGFP-C3 vector (BD biosciences Clontech, CA) in the EcoR I and Xho I site (NEB, USA). The construct was verified by enzyme digestion and DNA sequencing. For transfection, human colon cancer cell lines HCT116 and HT29 were cultured to 60% -70% confluence in 6-well plates, then 100 pmol siRNA duplexes or 4 μg NPM1 expression plasmids and control vector were transfected with Lipofectamine 2000 (Invitrogen, Carlsbad, CA) according to the manufacturer’s instructions. After transfection for 48 hours, cells were harvested and used for further assays.
Cell migration and invasion assays
Cell migration and invasion assays were performed as described previously . Briefly, 48 hours after transfection, control and NPM1 knockdown cells or NPM1 over-expression cells were harvested, washed and resuspended, then 5 × 105 cells in 400 μl serum free medium was added into the transwell inserts with 8μm pore polycarbonate filters which coated with (invasion) or without matrigel (migration) (BD Biosciences, San Jose, CA). After 24h (migration) or 48h (invasion) incubation, non-migrated cells on the top of the membrane were removed with a cotton swab. Cells migrated to the bottom sides of the membrane were fixed and stained. The number of migrated cells on the membrane was then counted in 3 randomly selected fields and taken the picture under a light microscope (Nikon SMZ 1000) at 400× magnification. All the experiments were performed at least three times.
Control and siNPM1 colon cancer cells or NPM1 over-expression cells were plated in a 96-well microplate at densities of 2000 per well. The cells were cultured continuously for 4 days, upon analysis, 20μl of MTT reagent (5 mg/ml, Sigma, USA) was added into each well and the cells were incubated at 37°C for 4 h. Then the supernatant was discarded and 150ul of DMSO was added into each well, after incubation at 37°C for 30min, the absorbance was measured at 570 nm.
BrdU incorporation assay
Cell proliferation assay was performed using a Cell Proliferation ELISA System (Roche Molecular Biochemicals, Mannheim, Germany) according to the manufacturer’s protocol. Cells were seeded onto 96-well plates at a density of 5000 cells per well and cultured for 24 h. BrdU solution (10 μM) was added to each well and the cells were incubated for another 4 h. The cells were then fixed, denatured, and immunostained with anti-BrdU antibody. BrdU incorporation was measured using an ELISA plate reader at 450 nm absorbance.
Colon cancer cells were grown on sterile slips for 24 h, washed three times with PBS, and fixed in ice-cold ethanol for 10 min. Endogenous peroxidase activity was suppressed by incubation with 3% H2O2 in methanol for 10 min. After blocking with normal serum for 30 min, the cells were incubated with a working solution containing mouse anti-human proliferating cell nuclear antigen (PCNA) antibodies (ZhongShan Co., China) for 2 h at room temperature. Incubation with HRP-conjugated secondary antibody for 1 h at 37°C followed. The signal was detected using a commercial kit (Dako EnVision System, CA, and USA). The slides were mounted and observed under a light microscope (Nikon SMZ 1000) at 400× magnification. Five areas were randomly chosen to count the number of PCNA-positive staining cells. The PCNA staining index was calculated by counting the number of PCNA-positive staining cells per 100 cells.
Wound healing assay
Cells were plated in 35 mm dishes at a density of 7.5 × 105 cells per ml and cultured to form confluent cell monolayers. Then cells were scraped with a 10 μl pipette tip and washed with PBS to remove nonadherent cells, followed by incubation in medium containing 0.5% FBS at 37°C for 0, 3, 6, 9, 12 and 24 h. The wound areas were calculated and photographed under a phase contrast microscopy at 100× magnifications (Olympus CKX41, JP). The migration distance was quantified by subtracting the width of the wounds at each time point from the width of the initial wounds. All experiments were repeated three times, and the quantitative data were expressed as mean ± SD.
Western blot analysis
Control group and experimental group of cells were plated on 10cm dish and cultured to 90% confluence. The cells were washed three times with cold PBS and lysed in 1x SDS cell lysis buffer containing a protease inhibitor cocktail (Roche Applied Science, Indianapolis, IN). Then, the cell lysates were boiled at 95°C for 5 minutes, cooled on ice, after centrifugation at 12,000g at 4°C for 15 minutes, protein concentration was determined by using a BCA™ Protein Assay Kit (Thermo, USA). 15ug of lysates was separated by 10% SDS-PAGE and transferred onto a PVDF membrane (Millipore, Bedford, MA), then the membrane was blocked with 5% nonfat milk for 1 h and incubated with monoclonal mouse anti-human NPM1 antibody (Santa Cruz, Biotechnology, CA 1:2000) overnight at 4°C. The membrane was then washed three times with TBST (TBS + 0.1% Tween-20) and incubated with a HRP-conjugated secondary antibody for 1 hour at room temperature, β-actin (Santa Cruz, Biotechnology, CA) (1:2500) was used as a loading control. An enhanced chemiluminescence reagents ECL kit (Sigma, USA) was used to examine the expression of indicated proteins.
All data were analyzed by Statistical Package for the Social Sciences (SPSS 17.0 Chicago, IL) and GraphPad Prism 5 statistical software (San Diego, CA, USA). Chi-squre test or student’s T-test (two-tailed) and one-way ANOVA were used for data analysis. The survival curve of patients was calculated by Kaplan-Meier method. A P value less than 0.05 was considered statistically significant.
High-expression of NPM1 is associated with lymph node metastasis in colonic carcinoma
Expression of NPM1 in colon cancer tissues, adjacent normal tissues and matched metastatic lymph nodes
Adjacent normal tissues
Colon cancer tissues
Metastatic lymph nodes
Correlation of NPM1 expression with clinicopathologic parameters of colon cancer patients
Expression of NPM1 was elevated in highly invasively colon cancer cell line
Down-regulation of NPM1 inhibited cancer cell proliferation
Reduction of NPM1 impaired Human colon cancer cell migration and invasion
The current study speculated that NPM1 may play a role in the elevated invasive potential of cancer cells and investigated the effect of NPM1 knockdown on cancer cell migration and invasion using a Boyden chamber assay. The current data showed that the migration and invasiveness of HCT116 cells transfected with NPM1-specific siRNA significantly decreased compared with that of the cells transfected with control siRNA ( Additional file 1,Figure 3E ). These results suggested that NPM1 plays an important role in the migration and invasion of colon cancer cells.
Exogenous expression of NPM1 enhanced migration and invasion ability of HT29 cells
NPM1 is a multifunctional nucleolar phosphoprotein that plays an essential role in cell growth and proliferation by regulating cell cycle progression,ribosome biogenesis, and centrosome duplication [10, 33, 34]. NPM1 is also crucial for maintaining genomic stability by influencing DNA replication and repair . The molecular chaperone activity of NPM1 is critical for DNA-histone assembly and proper protein folding. In addition, NPM1 is involved in transcription activation through its interaction with transcription factors, such as c-Myc, NF-κB, and FOXM1 [36–38]. Given the fact that NPM1 functions as a key regulator for many cellular activities , the contribution of NPM1 to oncogenesis has received much attention. Interestingly, previous studies revealed that NPM1 acts as both tumor suppressor and proto-oncogene during tumorigenesis . On one hand, NPM1 functions as a tumor promoter through the inhibition of several tumor suppressors including P53 and Rb via direct binding. NPM1 can also interact with proto-oncogene c-Myc and enhance its transforming activity . On the other hand, NPM1 is a potential tumor suppressor by maintaining chromosome stability and regulating ARF activity [40, 41].
Numerous studies demonstrated that the contribution of NPM1 to tumorigenesis depend on its expression level and genetic modifications . Most studies on NPM1 concentrated on human hematopoietic malignancies, and mutations of NPM1 are frequently observed in these tumors, especially in AML. In contrast to AML, a recent study found that mutated NPM1 is rarely detected in solid tumors. Instead, altered expression of NPM1 was observed in many types of solid tumors, and the detailed functions are just starting to be clarified . In the current study, evidence that NPM1 expression was remarkably increased in the colon cancer tissues and metastatic lymph nodes compared with the adjacent noncancerous tissues was provided. Statistical analysis showed that the overexpression of NPM1 was associated with distant metastasis, suggesting that NPM1 might play a critical role in colon carcinogenesis and colon cancer metastasis. Another study also showed that increased NPM1 expression correlated with tumor progression in hepatocellular carcinoma , which was consistent with the current result. In addition, a positive correlation was also found between the high expression of NPM1 and the poor five-year survival performance of colon cancer patients. Interestingly, similar results were also observed in other solid tumors [45, 46], indicating that NPM1 may be a potential prognosis marker for cancer patients.
Although much evidence demonstrates that NPM1 expression correlates with clinical parameters of cancer patients, the detailed role of NPM1 in cancer progression is largely unknown. The current finding on the increased expression of NPM1 in highly metastatic HCT116 colon cancer cells probably indicate that NPM1 is involved in colon cancer metastasis, in addition to cell growth regulation and proliferation. In support of this hypothesis, the present results showed that siRNA induced the down-regulation of NPM1-inhibited migration and invasion of human colon cancer cell HCT116 along with decreased cell proliferation. Furthermore, exogenous expression of wild-type NPM1 in HT29 cells enhanced cell migration and invasiveness. Migration and invasion is critical for cancer cell metastasis, thus, the current results provided direct evidence that the expression level of NPM1 is necessary for colon cancer cell metastasis. Interestingly, a recent study reported that mutant NPM1 promoted migration and invasion in NIH3T3 cells . In contrast to this finding, mutations of NPM1 inhibited cell migration in HEK293 cells . The effect of NPM1 on cell migration may be cell type-dependent because NPM1 mutations are a rare event in most solid tumors . However, its detailed role in cancer cell metastasis needs further investigation.
The current results suggested that the elevated expression of NPM1 correlated with distant metastasis and poor survival of colon cancer patients. The current study also provided the first direct evidence that the expression level of NPM1 is critical for colon cancer cell migration and invasion. Although the detailed mechanism of NPM1 in colon carcinogenesis remains to be elucidated, the present study speculated that NPM1 may be a potential prognosis biomarker and a possible therapeutic target for colon cancer patients.
acute myeloid leukemia
proliferating cell nuclear antigen.
This research was supported by grants from NSFC (81001188) and NSFC (81072160) and 973 Project (2011CB933100) and TSTC (12JCQNJC07000) and Tianjin higher education Science & Technology Fund Planning Project (20100120).
- Xu AG, Yu ZJ, Jiang B, Wang XY, Zhong XH, Liu JH, Lou QY, Gan AH: Colorectal cancer in Guangdong Province of China: a demographic and anatomic survey. World J Gastroenterol. 2010, 16: 960-965. 10.3748/wjg.v16.i8.960.PubMed CentralView ArticlePubMedGoogle Scholar
- Lai YL, Lin JK, Liang WY, Huang YC, Chang SC: Surgical resection combined with chemotherapy can help achieve better outcomes in patients with primary colonic lymphoma. J Surg Oncol. 2011, 104: 265-268. 10.1002/jso.21927.View ArticlePubMedGoogle Scholar
- Cummings J, Ethell BT, Jardine L, Boyd G, Macpherson JS, Burchell B, Smyth JF, Jodrell DI: Glucuronidation as a mechanism of intrinsic drug resistance in human colon cancer: reversal of resistance by food additives. Cancer Res. 2003, 63: 8443-8450.PubMedGoogle Scholar
- Koukourakis GV, Sotiropoulou-Lontou A: Targeted therapy with bevacizumab (Avastin) for metastatic colorectal cancer. Clin Transl Oncol. 2011, 13: 710-714. 10.1007/s12094-011-0720-z.View ArticlePubMedGoogle Scholar
- Behl A: PS1-30: Cost-Effectiveness Analysis of Screening for Kras and Braf Genetic Mutations in Metastatic Colorectal Cancer. Clin Med Res. 2011, 9: 174-PubMed CentralView ArticleGoogle Scholar
- Feuerstein N, Mond JJ: Identification of a prominent nuclear protein associated with proliferation of normal and malignant B cells. J Immunol. 1987, 139: 1818-1822.PubMedGoogle Scholar
- Schmidt-Zachmann MS, Hugle-Dorr B, Franke WW: A constitutive nucleolar protein identified as a member of the nucleoplasmin family. EMBO J. 1987, 6: 1881-1890.PubMed CentralPubMedGoogle Scholar
- Grisendi S, Mecucci C, Falini B, Pandolfi PP: Nucleophosmin and cancer. Nat Rev Cancer. 2006, 6: 493-505. 10.1038/nrc1885.View ArticlePubMedGoogle Scholar
- Okuda M, Horn HF, Tarapore P, Tokuyama Y, Smulian AG, Chan PK, Knudsen ES, Hofmann IA, Snyder JD, Bove KE, Fukasawa K: Nucleophosmin/B23 is a target of CDK2/cyclin E in centrosome duplication. Cell. 2000, 103: 127-140. 10.1016/S0092-8674(00)00093-3.View ArticlePubMedGoogle Scholar
- Okuda M: The role of nucleophosmin in centrosome duplication. Oncogene. 2002, 21: 6170-6174. 10.1038/sj.onc.1205708.View ArticlePubMedGoogle Scholar
- Li QF, Tang J, Liu QR, Shi SL, Chen XF: Localization and altered expression of nucleophosmin in the nuclear matrix during the differentiation of human hepatocarcinoma SMMC-7721 cells induced by HMBA. Cancer Invest. 2010, 28: 1004-1012. 10.3109/07357900902918452.View ArticlePubMedGoogle Scholar
- Li Z, Boone D, Hann SR: Nucleophosmin interacts directly with c-Myc and controls c-Myc-induced hyperproliferation and transformation. Proc Natl Acad Sci U S A. 2008, 105: 18794-18799. 10.1073/pnas.0806879105.PubMed CentralView ArticlePubMedGoogle Scholar
- Gadad SS, Senapati P, Syed SH, Rajan RE, Shandilya J, Swaminathan V, Chatterjee S, Colombo E, Dimitrov S, Pelicci PG: The multifunctional protein nucleophosmin (NPM1) is a human linker histone H1 chaperone. Biochemistry. 2011, 50: 2780-2789. 10.1021/bi101835j.View ArticlePubMedGoogle Scholar
- Chang TP, Yu SL, Lin SY, Hsiao YJ, Chang GC, Yang PC, Chen JJ: Tumor suppressor HLJ1 binds and functionally alters nucleophosmin via activating enhancer binding protein 2alpha complex formation. Cancer Res. 2010, 70: 1656-1667. 10.1158/0008-5472.CAN-09-2453.View ArticlePubMedGoogle Scholar
- Cilloni D, Messa F, Rosso V, Arruga F, Defilippi I, Carturan S, Catalano R, Pautasso M, Panuzzo C, Nicoli P: Increase sensitivity to chemotherapeutical agents and cytoplasmatic interaction between NPM leukemic mutant and NF-kappaB in AML carrying NPM1 mutations. Leukemia. 2008, 22: 1234-1240. 10.1038/leu.2008.68.View ArticlePubMedGoogle Scholar
- Colombo E, Alcalay M, Pelicci PG: Nucleophosmin and its complex network: a possible therapeutic target in hematological diseases. Oncogene. 2011, 30: 2595-2609. 10.1038/onc.2010.646.View ArticlePubMedGoogle Scholar
- Tsui KH, Juang HH, Lee TH, Chang PL, Chen CL, Yung BY: Association of nucleophosmin/B23 with bladder cancer recurrence based on immunohistochemical assessment in clinical samples. Acta Pharmacol Sin. 2008, 29: 364-370. 10.1111/j.1745-7254.2008.00747.x.View ArticlePubMedGoogle Scholar
- Montazeri A, Vahdaninia M, Harirchi I, Harirchi AM, Sajadian A, Khaleghi F, Ebrahimi M, Haghighat S, Jarvandi S: Breast cancer in Iran: need for greater women awareness of warning signs and effective screening methods. Asia Pac Fam Med. 2008, 7: 6-10.1186/1447-056X-7-6.PubMed CentralView ArticlePubMedGoogle Scholar
- Pianta A, Puppin C, Passon N, Franzoni A, Romanello M, Tell G, Di Loreto C, Bulotta S, Russo D, Damante G: Nucleophosmin delocalization in thyroid tumour cells. Endocr Pathol. 2011, 22: 18-23. 10.1007/s12022-011-9147-x.View ArticlePubMedGoogle Scholar
- Shao HY, Miao ZY, Hui C, Qin FX, Chen XC, Tan S, Zhang HJ, Wang L, Gao YJ, Yang ZL, Zhang L: Nucleophosmin gene mutations promote NIH3T3 cell migration and invasion through CXCR4 and MMPs. Exp Mol Pathol. 2011, 90: 38-44. 10.1016/j.yexmp.2010.11.009.View ArticlePubMedGoogle Scholar
- Zhang F, Zhang L, Zhang B, Wei X, Yang Y, Qi RZ, Ying G, Zhang N, Niu R: Anxa2 plays a critical role in enhanced invasiveness of the multidrug resistant human breast cancer cells. J Proteome Res. 2009, 8: 5041-5047. 10.1021/pr900461c.View ArticlePubMedGoogle Scholar
- Dessein AF, Stechly L, Jonckheere N, Dumont P, Monte D, Leteurtre E, Truant S, Pruvot FR, Figeac M, Hebbar M: Autocrine induction of invasive and metastatic phenotypes by the MIF-CXCR4 axis in drug-resistant human colon cancer cells. Cancer Res. 2010, 70: 4644-4654. 10.1158/0008-5472.CAN-09-3828.View ArticlePubMedGoogle Scholar
- Choi SR, Cho M, Kim HR, Ahn DH, Sleisenger MH, Kim YS: Biological properties and expression of mucins in 5-fluorouracil resistant HT29 human colon cancer cells. Int J Oncol. 2000, 17: 141-147.PubMedGoogle Scholar
- Demers MJ, Thibodeau S, Noel D, Fujita N, Tsuruo T, Gauthier R, Arguin M, Vachon PH: Intestinal epithelial cancer cell anoikis resistance: EGFR-mediated sustained activation of Src overrides Fak-dependent signaling to MEK/Erk and/or PI3-K/Akt-1. J Cell Biochem. 2009, 107: 639-654. 10.1002/jcb.22131.View ArticlePubMedGoogle Scholar
- Brattain MG, Brattain DE, Fine WD, Khaled FM, Marks ME, Kimball PM, Arcolano LA, Danbury BH: Initiation and characterization of cultures of human colonic carcinoma with different biological characteristics utilizing feeder layers of confluent fibroblasts. Oncodev Biol Med. 1981, 2: 355-366.PubMedGoogle Scholar
- Yeung TM, Gandhi SC, Wilding JL, Muschel R, Bodmer WF: Cancer stem cells from colorectal cancer-derived cell lines. Proc Natl Acad Sci U S A. 2010, 107: 3722-3727. 10.1073/pnas.0915135107.PubMed CentralView ArticlePubMedGoogle Scholar
- Sanchez-Arago M, Chamorro M, Cuezva JM: Selection of cancer cells with repressed mitochondria triggers colon cancer progression. Carcinogenesis. 2010, 31: 567-576. 10.1093/carcin/bgq012.View ArticlePubMedGoogle Scholar
- Shandilya J, Swaminathan V, Gadad SS, Choudhari R, Kodaganur GS, Kundu TK: Acetylated NPM1 localizes in the nucleoplasm and regulates transcriptional activation of genes implicated in oral cancer manifestation. Mol Cell Biol. 2009, 29: 5115-5127. 10.1128/MCB.01969-08.PubMed CentralView ArticlePubMedGoogle Scholar
- Sandsmark DK, Zhang H, Hegedus B, Pelletier CL, Weber JD, Gutmann DH: Nucleophosmin mediates mammalian target of rapamycin-dependent actin cytoskeleton dynamics and proliferation in neurofibromin-deficient astrocytes. Cancer Res. 2007, 67: 4790-4799. 10.1158/0008-5472.CAN-06-4470.View ArticlePubMedGoogle Scholar
- Kim CK, Nguyen TL, Lee SB, Park SB, Lee KH, Cho SW, Ahn JY: Akt2 and nucleophosmin/B23 function as an oncogenic unit in human lung cancer cells. Exp Cell Res. 2011, 317: 966-975. 10.1016/j.yexcr.2010.12.013.View ArticlePubMedGoogle Scholar
- Qin FX, Shao HY, Chen XC, Tan S, Zhang HJ, Miao ZY, Wang L, Hui C, Zhang L: Knockdown of NPM1 by RNA interference inhibits cells proliferation and induces apoptosis in leukemic cell line. Int J Med Sci. 2011, 8: 287-294.PubMed CentralView ArticlePubMedGoogle Scholar
- Korgaonkar C, Hagen J, Tompkins V, Frazier AA, Allamargot C, Quelle FW, Quelle DE: Nucleophosmin (B23) targets ARF to nucleoli and inhibits its function. Mol Cell Biol. 2005, 25: 1258-1271. 10.1128/MCB.25.4.1258-1271.2005.PubMed CentralView ArticlePubMedGoogle Scholar
- Ginisty H, Amalric F, Bouvet P: Nucleolin functions in the first step of ribosomal RNA processing. EMBO J. 1998, 17: 1476-1486. 10.1093/emboj/17.5.1476.PubMed CentralView ArticlePubMedGoogle Scholar
- Chartier NT, Oddou CI, Laine MG, Ducarouge B, Marie CA, Block MR, Jacquier-Sarlin MR: Cyclin-dependent kinase 2/cyclin E complex is involved in p120 catenin (p120ctn)-dependent cell growth control: a new role for p120ctn in cancer. Cancer Res. 2007, 67: 9781-9790. 10.1158/0008-5472.CAN-07-0233.PubMed CentralView ArticlePubMedGoogle Scholar
- Lindstrom MS: NPM1/B23: A Multifunctional Chaperone in Ribosome Biogenesis and Chromatin Remodeling. Biochem Res Int. 2011, 2011: 195209-PubMed CentralView ArticlePubMedGoogle Scholar
- Lin CY, Liang YC, Yung BY: Nucleophosmin/B23 regulates transcriptional activation of E2F1 via modulating the promoter binding of NF-kappaB, E2F1 and pRB. Cell Signal. 2006, 18: 2041-2048. 10.1016/j.cellsig.2006.04.001.View ArticlePubMedGoogle Scholar
- Bhat UG, Jagadeeswaran R, Halasi M, Gartel AL: Nucleophosmin interacts with FOXM1 and modulates the level and localization of FOXM1 in human cancer cells. J Biol Chem. 2011, 286: 41425-41433. 10.1074/jbc.M111.270843.PubMed CentralView ArticlePubMedGoogle Scholar
- Yeh CW, Huang SS, Lee RP, Yung BY: Ras-dependent recruitment of c-Myc for transcriptional activation of nucleophosmin/B23 in highly malignant U1 bladder cancer cells. Mol Pharmacol. 2006, 70: 1443-1453. 10.1124/mol.106.024810.View ArticlePubMedGoogle Scholar
- Di Fiore PP: Playing both sides: nucleophosmin between tumor suppression and oncogenesis. J Cell Biol. 2008, 182: 7-9. 10.1083/jcb.200806069.PubMed CentralView ArticlePubMedGoogle Scholar
- Brady SN, Yu Y, Maggi LB: Weber JD: ARF impedes NPM/B23 shuttling in an Mdm2-sensitive tumor suppressor pathway. Mol Cell Biol. 2004, 24: 9327-9338. 10.1128/MCB.24.21.9327-9338.2004.PubMed CentralView ArticlePubMedGoogle Scholar
- Enomoto T, Lindstrom MS, Jin A, Ke H, Zhang Y: Essential role of the B23/NPM core domain in regulating ARF binding and B23 stability. J Biol Chem. 2006, 281: 18463-18472. 10.1074/jbc.M602788200.View ArticlePubMedGoogle Scholar
- Pianta A, Puppin C, Franzoni A, Fabbro D, Di Loreto C, Bulotta S, Deganuto M, Paron I, Tell G, Puxeddu E: Nucleophosmin is overexpressed in thyroid tumors. Biochem Biophys Res Commun. 2010, 397: 499-504. 10.1016/j.bbrc.2010.05.142.View ArticlePubMedGoogle Scholar
- Jeong EG, Lee SH, Yoo NJ: Absence of nucleophosmin 1 (NPM1) gene mutations in common solid cancers. APMIS. 2007, 115: 341-346. 10.1111/j.1600-0463.2007.apm_592.x.View ArticlePubMedGoogle Scholar
- Yun JP, Miao J, Chen GG, Tian QH, Zhang CQ, Xiang J, Fu J, Lai PB: Increased expression of nucleophosmin/B23 in hepatocellular carcinoma and correlation with clinicopathological parameters. Br J Cancer. 2007, 96: 477-484. 10.1038/sj.bjc.6603574.PubMed CentralView ArticlePubMedGoogle Scholar
- Tsui KH, Cheng AJ, Chang PL, Pan TL, Yung BY: Association of nucleophosmin/B23 mRNA expression with clinical outcome in patients with bladder carcinoma. Urology. 2004, 64: 839-844. 10.1016/j.urology.2004.05.020.View ArticlePubMedGoogle Scholar
- Kikuta K, Tochigi N, Shimoda T, Yabe H, Morioka H, Toyama Y, Hosono A, Beppu Y, Kawai A, Hirohashi S, Kondo T: Nucleophosmin as a candidate prognostic biomarker of Ewing's sarcoma revealed by proteomics. Clin Cancer Res. 2009, 15: 2885-2894. 10.1158/1078-0432.CCR-08-1913.View ArticlePubMedGoogle Scholar
- Zhang W, Navenot JM, Frilot NM, Fujii N, Peiper SC: Association of nucleophosmin negatively regulates CXCR4-mediated G protein activation and chemotaxis. Mol Pharmacol. 2007, 72: 1310-1321. 10.1124/mol.107.037119.View ArticlePubMedGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.