The FOXK1-CCDC43 Axis Promotes the Invasion and Metastasis of Colorectal Cancer Cells.

BACKGROUND/AIMS: The CCDC43 gene is conserved in human, rhesus monkey, mouse and zebrafish. Bioinformatics studies have demonstrated the abnormal expression of CCDC43 gene in colorectal cancer (CRC). However, the role and molecular mechanism of CCDC43 in CRC remain unknown. METHODS: The functional role of CCDC43 and FOXK1 in epithelial-mesenchymal transition (EMT) was determined using immunohistochemistry, flow cytometry, western blot, EdU incorporation, luciferase, chromatin Immunoprecipitation (ChIP) and cell invasion assays. RESULTS: The CCDC43 gene was overexpressed in human CRC. High expression of CCDC43 protein was associated with tumor progression and poor prognosis in patients with CRC. Moreover, the induction of EMT by CCDC43 occurred through TGF-ß signaling. Furthermore, a positive correlation between the expression patterns of CCDC43 and FOXK1 was observed in CRC cells. Promoter assays demonstrated that FOXK1 directly bound and activated the human CCDC43 gene promoter. In addition, CCDC43 was necessary for FOXK1- mediated EMT and metastasis in vitro and vivo. Taken together, this work identified that CCDC43 promoted EMT and was a direct transcriptional target of FOXK1 in CRC cells. CONCLUSION: FOXK1-CCDC43 axis might be helpful to develop the drugs for the treatment of CRC.

Inhibition of migration and invasion of colorectal cancer cells via deletion of Rac1 with RNA interference.

Cell migration and invasion are triggered by a number of chemoattractants that stimulate intracellular signaling pathways through regulating reorganization of the actin cytoskeleton. Rac1, an intracellular signal transducer, regulates a variety of cell functions, including the organization of the cytoskeleton, cell migration, and invasion. However, currently, very little is known about the roles of Rac1 in the cytoskeleton formation and invasion of human colorectal cancer cells. In our study, Rac1-shRNA was used to silence the Rac1 to reduce its expression specifically in Lovo cells. Our studies showed that RNA interference-mediated deletion of Rac1 strongly inhibited lamellipodia formation, cell migration, and invasion of Lovo cells in vitro. The deletion of Rac1 can serve as an alterative therapy to inhibit the invasion and metastasis of colorectal cancer cells.

[Role of Rac1 activation in migration and invasion of colorectal cancer cell line SW480].

OBJECTIVE: To study the role of activation of Rac1 in colorectal cancer cell migration and invasion. METHODS: Rac1 L61 plasmid and control plasmid were transfected into colorectal cancer cell line SW480 cells. Pull down assay by Western blotting was carried out to measure the amount of activited Rac1, and transwell permeable supports were used to assess the migration and invasion of SW480 cells with different activitivity of Rac1. RESULTS: The transfection ratio of SW480 cells was more than 80%. Pull down assay showed that the activited Rac1 was significantly higher in the SW480 cells transfected with Rac1 L61 plasmid than that in the control, and the amount of migrating and invasing SW480 cells transfected with Rac1 L61 plasmid in the Transwell permeable supports were significantly more than those in controls (migrating cell numbers: 43 +/- 9 vs. 22 +/- 5, P < 0.01; invasing cell numbers: 73 +/- 13 vs. 38 +/- 1, P < 0.01). CONCLUSION: The activation of Rac1 plays an important role in the migration and invasion of colorectal cancer cells.

[Claudin-3 expression in colorectal carcinoma and its significance].

OBJECTIVE: To investigate the expression of claudin-3 in colorectal carcinoma and its association with the occurrence, progression and prognosis of colorectal cancer. METHODS: Forty surgical specimens of colorectal carcinoma and 22 adjacent normal tissues resected between October, 2010 and January, 2013 at Nanfang Hospital were examined for claudin-3 expression using immunohistochemistry, which was analyzed in association with the clinicopathological parameters and the survival of the patients. RESULTS: Claudin-3 was expressed mainly on the cell membrane, and its positivity rate was significantly higher in cancer tissues than in normal tissues (92.50% vs 59.09%, P<0.05). In 13 cases claudin-3 expression was detected in both the cancer tissues and adjacent normal tissues with average expression scores of 4.538 and 3.269, respectively (P<0.05). In the cancer tissues, the strongly positive expression rate was significantly higher in poorly differentiated tissues (85.71%) than in well (21.43%) and moderately (36.48%) differentiated tissues (P<0.05), and was higher in cases with lymph node metastasis than in those without (61.11% vs 22.72%, P<0.05). The strongly positive expression rate of claudin-3 was not correlated with the patients'age, gender, tumor location or tumor size (P>0.05). Of the 33 cancer patients followed up, 14 had a postoperative survival time no longer than 3 years and 19 had longer survival time, and their average expression scores differed significantly (4.50 vs 3.526, P<0.05). CONCLUSION: Claudin-3 is over-expressed in colorectal cancer tissues, and its high expression may promote the occurrence and progression of colorectal cancer. Claudin-3 may serve as a molecular biomarker for early diagnosis and prognostic evaluation.

Direct regulation of FOXK1 by C-jun promotes proliferation, invasion and metastasis in gastric cancer cells.

Forkhead box (FOX) K1 is a member of the FOX transcription factor superfamily. High FOXK1 expression is associated with several cancers. However, whether FOXK1 expression contributes to gastric cancer (GC) development and progression remains unknown. We analyzed the FOXK1 promoter using the Promo software and found several binding sequence transcription factors, including c-jun. However, the molecular mechanism by which FOXK1 affects the c-jun-mediated malignant phenotype is poorly understood. Here, we found that FOXK1 protein expression was higher in 8/10 (80.0%) fresh cancer tissues compared with that in adjacent normal tissues. FOXK1 overexpression enhanced the proliferation, migration and invasion of GC cells. Moreover, FOXK1 expression was stimulated by transforming growth factor-ß1 (TGF-ß1). FOXK1 acted as a potential epithelial-to-mesenchymal transition (EMT) inducer by stimulating vimentin expression and inducing the loss of E-cadherin in stable FOXK1-transfected cells. The results of promoter reporter and chromatin immunoprecipitation assays demonstrated that c-jun directly binds to and activates the human FOXK1 gene promoter. A positive correlation was observed between the expression patterns of FOXK1 and c-jun in GC cells and tissue. FOXK1 and c-jun expression were correlated with tumor progression and represented significant predictors of overall survival in GC patients. However, the siRNA-mediated repression of c-jun in FOXK1-overexpressing cells reversed EMT, as well as the proliferative and metastatic phenotypes. In vivo, c-jun promoted FOXK1-mediated proliferation and metastasis via orthotopic implantation. The evidence presented here suggests that FOXK1-directed regulation by c-jun promote the development and progression of human GC.

Knockdown of FOXK1 alone or in combination with apoptosis-inducing 5-FU inhibits cell growth in colorectal cancer.

Forkhead box K1 (FOXK1) is a member of the FOX transcription factor family, which plays an important role in oncogenesis. However, the exact function and mechanism of FOXK1 in human colorectal cancers (CRCs) remain unclear. In the present study, we first screened for potential FOXK1 target genes by ectopically expressing FOXK1 in SW480 cells and examined the subsequent changes in the expression levels of major oncogenes using RT-PCR. We also evaluated the effects of FOXK1 regulation on growth and apoptosis. In addition, we investigated the biological impact of FOXK1 knockdown on CRC cells in vitro and in vivo. We found that FOXK1 overexpression increased the expression of multiple oncogenes in vitro. FOXK1 promoted serum-dependent and anchorage-dependent and -independent cell growth. Knockdown of FOXK1 induced G0/G1 cell cycle arrest in CRC cells. Moreover, FOXK1 suppression induced apoptosis and increased cell susceptibility to 5-fluorouracil (5-FU)-induced apoptosis. Furthermore, a xenograft model was established to explore FOXK1 shRNA-mediated tumorigenesis in vivo. A strong antitumorigenic effect of FOXK1-shRNA was enhanced when combined with 5-FU treatment. These findings implicate FOXK1 as a cell cycle and growth modulator that inhibits apoptosis in colon cancer cells. FOXK1-shRNA may serve as a novel and potent therapeutic agent, alone or with 5-FU, against colon cancer.

Oncogene FOXK1 enhances invasion of colorectal carcinoma by inducing epithelial-mesenchymal transition.

Transcriptional factor FOXK1 is a member of the FOX family, involved in the cell growth and metabolism. The higher expression of FOXK1 leads to a variety of diseases and may play an important role in the development of various tumors. However, the role of FOXK1 in the progression of colorectal cancer (CRC) remains unknown. We demonstrated that FOXK1 was overexpressed in 16 types of solid tumor tissues via tissue multi-array (TMA). We found that FOXK1 induced elevated expressions and transactivities of five major oncogenes in CRC. Moreover, the elevated expression of FOXK1 was showed to be correlated with tumor progression and was a significant predictor of overall survival in CRC patients. Furthermore, it was showed that the depletion of FOXK1 expression could inhibit the migratory and invasive abilities of CRC cells. In contrast, ectopic expression of FOXK1 elicited the opposite effects on these phenotypes in vitro. FOXK1 promoted tumor metastasis through EMT program induction. In addition, TGF-ß1 induced FOXK1 expression in a time-dependent pattern and the knockdown of FOXK1 inhibited TGF-ß1-induced EMT. In vivo, higher expression of FOXK1 promotes CRC cell invasion and metastasis, and induces EMT in CRC as well. Alltogether, it was concluded that the higher expression of FOXK1 could indicate a poor prognosis in CRC patients since that FOXK1 induces EMT and promotes CRC cell invasion in vitro and in vivo.

[Expressions of tumor necrosis factor receptor I and II in human gastric carcinoma].

OBJECTIVE: To study the clinical significance of expressions of tumor necrosis factor receptor I and II(TNFR I and II) and their relationship with clinical pathology in human gastric carcinoma. METHODS: SABC immunohistochemical method was used to examine the expressions of TNFR I and II in 51 cases of gastric carcinoma, 41 adjacent mucosal and 15 normal gastric mucosa tissues. RESULTS: The positivity rates of TNFR I and II expressions in human gastric carcinoma were significantly higher than those in the adjacent mucosal and normal mucosal tissues, and their expressions were significantly higher in the surrounding mucosa than in the normal tissues. In gastric carcinoma tissues, no correlations of TNFR I and II expressions with serous membrane invasion or lymph node metastasis were found, but the differentiation grade was positively correlated with TNFR expressions (r=-0.3111, P=0.035; r=-0.5952, P=0.000, respectively). CONCLUSION: TNFR I and II expressions are valuable indicators for determining the malignancy and predicting the differentiation grade of gastric carcinoma.

KLF8 promotes tumorigenesis, invasion and metastasis of colorectal cancer cells by transcriptional activation of FHL2.

The transcription factor Krüppel-like factor (KLF)8 plays an important role in the formation of several human tumors, including colorectal cancer. We recently identified four-and-a-half LIM protein 2 (FHL2) as a critical inducer of the epithelial-to-mesenchymal transition (EMT) and invasion. However, the molecular mechanism by which KLF8 affects FHL2-mediated tumor proliferation, EMT and metastasis remains unknown. Here, we showed that KLF8 overexpression promoted EMT and metastatic phenotypes. KLF8 expression was stimulated by transforming growth factor (TGF)-ß1. Moreover, KLF8 acted as a potential EMT inducer by stimulating vimentin expression and inducing a loss of E-cadherin in stable KLF8-transfected cells. KLF8 overexpression induced a strong increase in FHL2 expression, and a positive correlation between the expression patterns of KLF8 and FHL2 was observed in CRC cells. Promoter reporter and chromatin immunoprecipitation (ChIP) assays demonstrated that KLF8 directly bound to and activated the human FHL2 gene promoter. However, siRNA-mediated repression of FHL2 in KLF8-overexpressing cells reversed the EMT and the proliferative and metastatic phenotypes. In vivo, KLF8 promoted FHL2-mediated proliferation and metastasis via orthotopic implantation. Taken together, this work identified KLF8-induced FHL2 activation as a novel and critical signaling mechanism underlying human breast/colorectal cancer invasion and metastasis.

[Expression of tumor necrosis factor receptor on peripheral blood mononuclear cells from patients with primary hepatocellular carcinoma and effects of treatment on the expression].

OBJECTIVE: To conduct an intensive investigation of the abnormal immune status of patients with primary hepatocellular carcinoma and explore the possible mechanism of biotherapy for these patients. METHODS: The expression of tumor necrosis factor receptor (TNFR)I and TNFR II on peripheral blood mononuclear cells (PBMCs) obtained from 30 normal subjects and 31 patients with primary hepatocellular carcinoma were examined by flow cytometry and S-P staining assay. The effects of biotherapy and chemotherapy administered in the patients were also investigated in terms of the changes in the expressions. RESULTS: The TNFR I and TNFR II expressions in the patients were (28.35+/-9.09) % and (37.45+/-9.51) % respectively, significantly lower than those of normal subjects [(38.54+/-8.51) % and (44.89+/-9.08) %]. The biotherapy for the patients caused an increase of TNFR I expression to (42.86+/-9.02)%. CONCLUSION: There are significant immune abnormalities in patients with primary hepatocellular carcinoma, and this study may offer some theoretical basis for the implementation of biotherapy in such cases.

Detection of soluble tumor necrosis factor-p55 levels in the serum and ascitic fluid of patients with hepatocellular carcinoma.

OBJECTIVE: To examine soluble tumor necrosis factor receptor-p55 (sTNFR-p55) levels in the serum and ascitic fluid and investigate the significance of this examination in assessment of the clinical status of patients with primary hepatocellular carcinoma (HCC). METHODS: Enzyme-linked immunosorbent assay (ELISA) was used to examine sTNFR-p55 levels in the serum and ascitic fluid in 25 patients with HCC and 25 with liver cirrhosis (LC). RESULTS: sTNFR-p55 levels in the serum and ascitic fluid in patients with HCC were significantly higher than those in patients with LC and controls (P=0.001). No significant difference was found between LC and the control in terms of serum sTNFR-p55 levels (P=0.19). Positive correlation was observed between sTNFR-p55 levels in the serum and in ascitic fluid of patients with HCC and LC (r=1.000, P<0.001). Logistic regression revealed that in patients with HCC, serum sTNFR-p55 levels were positively correlated with TBil and AFP in the peripheral blood (r=0.524, P=0.01 and r=0.234, P=0.03, respectively). CONCLUSIONS: Increased sTNFRs-p55 levels in the serum and ascitic fluid reflect abnormal immune status of the patients with HCC and help predict the development of tumor.

[Effects of recombinant Helicobacter pylori catalase on oxidative stress in colonic mucosal epithelial cells].

OBJECTIVE: To investigate the effects of recombinant Helicobacter pylori catalase (rHpCAT)on oxidative stress in rat colonic mucosal epithelial cells. METHODS: Oxidative stress model was established by hydroxyl generated from Fenton reaction in cultured colonic mucosal epithelial cells isolated from normal rats, in the model of which the effects of rHpCAT were observed. The cells were divided into normal control, model, 5-aminosalicylic acid (5-ASA, 0.1 mmol/L), and rHpCAT (1 x 10(5), 1 x 10(6), and 1 x 10(7) U/kg, respectively) groups. At the end of the experiment, the content of lactic dehydrogenase (LDH), malondialdehyde (MDA), myeloperoxidase (MPO), glutathione peroxidase (GSH-Px), catalase (CAT) and, superoxide dismutase (SOD) were detected in the culture supernatant. RESULTS: The contents of LDH, MDA and MPO were elevated while those of GSH-Px, CAT and SOD reduced in the model group. rHpCAT at different doses reduced the release of LDH, depressed the contents of MDA and MPO, and increased the contents of GSH-Px, SOD and CAT. CONCLUSION: rHpCAT has protective effects against rat colonic mucosal oxidative damage.

Identification of differential gene expressions in colorectal cancer and polyp by cDNA microarray.

AIM: To screen the differential expressed genes in colorectal cancer and polyp tissue samples. METHODS: Tissue specimens containing 16 cases of colorectal adenocarcinoma and colorectal polyp vs normal mucosae were collected and subjected to cDNA microarray and bioinformatical analyses. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to confirm some of the cDNA microarray data. RESULTS: The experimental data showed that eight genes were differentially expressed, most of which were upregulated in adenomatous polyp lesions. Forty-six genes expressions were altered in colorectal cancers, of which 29 were upregulated and 17 downregulated, as compared to the normal mucosae. In addition, 18 genes were similarly altered in both adenomatous polyps and colorectal cancer. qRT-PCR analyses confirmed the cDNA microarray data for four of those 18 genes: MTA1, PDCD4, TSC1 and PDGFRA. CONCLUSION: These differentially expressed genes likely represent biomarkers for early detection of colorectal cancer and may be potential therapeutic targets after confirmed by further studies.

[Effect of small interfering RNA targeting Rac1 gene on colony formation of SW480 cells in vitro].

OBJECTIVE: To construct a vector expressing small interfering RNA (siRNA) against Rac1 gene and observe its effect on soft agar colony formation of SW480 cells in vitro. METHODS: Oligos of 64 base pairs for hairpin RNA targeting Rac1 were chemically synthesized and annealed. The siRNA constructs for Rac1, produced by inserting the annealed oligos into the downstream of H1 promoter of linearized pSUPER, were confirmed by restriction digestion and DNA sequencing. The constructed Rac1-siRNA was transfected into SW480 cells and Western blotting was performed to assess the expression and interference efficiency of siRNAs against Rac1.The soft agar colony formation assay was used to study the effect of Rac1 gene silencing on SW480 cells. RESULTS: Restriction digestion and DNA sequencing showed that the siRNA targeting Rac1 gene was successfully constructed. The siRNA could effectively down-regulate the expression of Rac1 in SW480 cells. Soft agar colony formation assay showed that the colony number and diameter of SW480 cells was reduced after siRNA transfection. CONCLUSION: A vector expressing hairpin RNA against Rac1 gene are successfully produced, which significantly reduces the colony numbers and size of SW480 cells in vitro, suggesting that Rac1 plays an important role in the growth of colorectal cancer in vitro.

[Effect of X-ray exposure on soluble tumor necrosis factor receptor-p75 release in hepatocellular carcinoma HepG2 cells in vitro].

OBJECTIVE: To investigate the effects of X-ray exposure on the release of soluble tumor necrosis factor receptor-p75 (sTNFR-p75) in hepatocellular carcinoma HepG2 cells in vitro. METHODS: Enzyme-linked immunosorbent assay (ELISA) was used to examine the levels of sTNFR-p75 in the supernatants of HepG2 cells before and after X-ray exposure. The cell apoptosis was analyzed by flow cytometry and transmission electron microscope(TEM), and the morphological changes of the cells were examined under optical microscope and transmission electron microscope(TEM). RESULTS: X-ray exposure of the cells resulted in a strong increase of cell apoptosis (P<0.05) and sTNFR-p75 production in the cells as compared with the those before the exposure (P<0.01). Optical microscopy revealed apoptotic changes of HepG2 cell after the exposure, shown as cell shrinkage, spherical cell morphology, cytoplasmic and nuclear condensation. Apoptotic bodies were detected by TEM. CONCLUSION: X-ray exposure induces HepG2 cells apoptosis by inhibiting the release of sTNFR-p75 into the supernatant.

[Effect of p21-activated kinase-1 on the invasiveness of colorectal carcinoma cells in vitro].

OBJECTIVE: To observe the effect of p21-activated kinase-1 (PAK1) gene transfection on the invasiveness of human colorectal carcinoma SW480 cells in vitro. METHODS: SW480 cells in routine culture were transfected with the recombinant plasmid EGFP-C1/PAK1 via Lipofectamine(TM) 2000. The expression of PAK1 protein in SW480 cells was detected using Western blotting, and the changes of the invasiveness of SW480 cells were evaluated using Boyden chamber invasion assay. RESULTS: Forty-eight hours after transfection with pEGFP-C1/ PAK1, the PAK1 protein expression increased significantly in comparison with those in negative and vector control groups. The invasiveness of the SW480 cells was significantly enhanced after the transfection. CONCLUSION: The PAK1 gene transfection can increase the expression of PAK1 in SW480 cells and enhance the invasiveness of the cells. PAK1 can be associated with the invasiveness and metastasis of colorectal carcinoma cells.

[Cloning of human migfilin N-terminal domain and preparation of anti-migfilin polyclonal antibody].

OBJECTIVE: To clone migfilin-N terminal sequence into E.coli and obtain a fusion protein for preparing rabbit polyclonal antibody against migfilin, thereby facilitating the study of the role of migfilin in the biological behavior of colon cancer. METHODS: Based on human migfilin cDNA sequence, a pair of primers was designed to amplify migfilin-N terminal sequence by PCR. The PCR product was subcloned into the bacterial expression vector pGEX-4T-1 with EcoRI/XhoI sites, and the target recombinant plasmids were identified with enzymatic cleavage followed by DNA sequence analysis. By transforming the expression vector into component E.coli BL(21) cells, the GST-migfilin-N fusion protein was expressed with IPTG induction. Glutathione-sepharose beads were used to purify the fusion protein, and anti-migfilin polyclonal antibody was produced by immunization of rabbits with the purified GST-migfilin N-terminal fusion protein. The resultant anti-migfilin polyclonal antibody was purified by protein A beads and used for Western blotting for detecting migfilin expression in different cell lines. RESULTS AND CONCLUSION: The migfilin-N terminal gene fragment was cloned successfully, and purified GST-migfilin N-terminal fusion protein and anti-rabbit migfilin polyclonal antibodies were obtained. Western blot analysis demonstrates that the antibodies specifically detected migfilin expression in the cell lines, which may facilitate further investigation of the role of migfilin in the biology of colon cancer.

[X-ray irradiation enhances tumor necrosis factor receptor p55 expression in human colorectal cancer cells and inhibits the release of its soluble form in vitro].

OBJECTIVE: To investigate the effects of X ray on human colorectal cancer cells for their tumor necrosis factor receptor-p55 (TNFR-p55) expression and release of soluble soluble TNFR-p55 (sTNFR-p55) in vitro. METHODS: The protein expression of TNFR-p55 in Lovo cells exposed to X-ray was detected using immunohistochemistry, and enzyme-linked immunosorbent assay was used to examine the levels of sTNFR-p55 in the supernatants of the cell culture. The cell apoptosis of the exposed cells was analyzed with flow cytometry, and the changes in cell morphology were observed microscopically. RESULTS: X-ray exposure of cells resulted in a strong increase in TNFR-p55 expression of (P<0.01) and LoVo cell apoptosis (P<0.05). The levels of sTNFR-p55 in the supernatant of cells with X-ray exposure was significantly lowered in comparison with the levels before exposure (P<0.01). Optical microscopy showed that the exposed LoVo cells shrank and became spherical with cytoplasmic condensation and nuclear pyknosis. CONCLUSION: X-ray exposure can induce LoVo cell apoptosis by increasing TNFR-p55 expression on the cell membrane and inhibiting the release of sTNFR-p55 in the supernatants.

[Short hairpin RNA-mediated survivin gene silencing inhibits invasion and metastasis of human colon carcinoma cell line SW480 in vitro].

OBJECTIVE: To investigate the effect of short hairpin RNA (shRNA) targeting survivin on adhesion and invasion of human colon carcinoma cell line SW480 in vitro. METHODS: According to the sequence of the coding region of survivin gene, two strings of 19 nucleotides of inverted sequence flanking the loop sequence of two complementary 9-base oligonucleotides were designed and synthesized to prepare the hairpin construct as the DNA templates for the target shRNA. The shRNA templates were cloned into shRNA expression vector pRNAT-U6.1/Neo, and the resulted vector pRNAT-U6.1/Neo-survivin was transfected into SW480 cells using Lipofectamine 2000. Western blotting was performed to evaluate survivin gene silencing induced by shRNA transfection at the protein level, and the biological behaviors of the SW480 cells were investigated by cell-matrix adhesion, invasion and gelatin-zymography assays. RESULTS: Western blotting revealed significantly lowered survivin protein expression in transfected SW480 cells, and survivin gene silencing induced by shRNA significantly suppressed the metastatic potential of SW480 cells in association with suppressed MMPs activity. CONCLUSIONS: Survivin may play an important role in modulating human colorectal carcinoma cell invasion and metastasis, and survivin gene silencing can inhibit human colorectal cancer cell invasion and the production of MMP-2 and MMP-9. Survivin may affect invasion and metastasis of human colorectal carcinoma cells via regulating the production of MMPs.