Colorectal Cancer Cell LoVo Research Articles

Down-regulated and Commonly mutated ALPK1 in Lung and Colorectal Cancers.

The ALPK1 gene located in the 4q25 region encodes a newly explored protein kinase which could phosphorylate the amino acid of a domain full of α-helices. Recently, several studies have indicated that the expression of ALPK1 is related to inflammation and various diseases; therefore, the purpose of this investigation was to determine whether the expression of ALPK1 has an influence on tumorigenesis and to further scrutinize its gene polymorphism in order to better understand its clinical importance. In lung and colorectal cancer tissues, the ALPK1 RNA level of the normal part was higher than that of the tumor part using the RT-qPCR analysis. Moreover, differences in HRM melting curves could effectively separate the known mutation sites and be used to identify the two novel variants that might cause the bio-dysfunctions of ALPK1 found in silico predictions. Additionally, in both Lovo colorectal and A549 lung cancer cells with enhanced and depleted expression of ALPK1, the encoded ALPK1 could exert its activity on cell migration without interfering with cell viability. Taken together, these findings suggested that ALPK1 might play a vital role in cancer development and that the newly explored SNPs are found in a Taiwanese cohort.

Inhibitor of growth 4 suppresses colorectal cancer growth and invasion by inducing G1 arrest, inhibiting tumor angiogenesis and reversing epithelial-mesenchymal transition.

Previous studies have found that inhibitor of growth 4 (ING4), a tumor suppressor, is reduced in human colorectal cancer (CRC), and is inversely correlated with clinical Dukes' stage, histological grade, lymph node metastasis and microvessel density (MVD). However, its underlying mechanism remains undetermined. In the present study, we analyzed ING4 expression in a panel of human CRC cells using low (LS174T and SW480) and high (LoVo and SW620) metastatic cell lines. We demonstrated that both the low and high metastatic CRC cells exhibited a lower level of ING4 compared to the level in normal human colorectal mucous epithelial FHC cells. Furthermore, ING4 expression in high metastatic CRC cells was less than that in low metastatic CRC cells. We then generated a lentivirus construct expressing ING4 and green fluorescent protein (GFP), established a ING4-stably transgenic LoVo CRC cell line, and investigated the effect of lentiviral-mediated ING4 expression on high metastatic LoVo CRC cells. Gain-of-function studies revealed that ING4 significantly inhibited LoVo CRC cell growth and invasion in vitro and induced cell cycle G1 phase arrest. Moreover, ING4 obviously suppressed LoVo CRC subcutaneously xenografted tumor growth and reduced tumor MVD in vivo in athymic BALB/c nude mice. Mechanistically, ING4 markedly upregulated P21 and E-cadherin but downregulated cyclin E, interleukin (IL)-6, IL-8, vascular endothelial growth factor (VEGF), Snail1, N-cadherin and vimentin in the LoVo CRC cells. Our data provide compelling evidence that i) ING4 suppresses CRC growth possibly via induction of G1 phase arrest through upregulation of P21 cyclin-dependent kinase (CDK) inhibitor and downregulation of cyclin E as well as inhibition of tumor angiogenesis through reduction of IL-6, IL-8 and VEGF proangiogenic factors; ii) ING4 inhibits CRC invasion and metastasis probably via a switch from mesenchymal marker N-cadherin to epithelial marker E-cadherin through downregulation of Snail1 epithelial-mesenchymal transition (EMT)-inducing transcription factor (EMT-TF).

The hypoxia-mimetic agent CoCl₂ induces chemotherapy resistance in LOVO colorectal cancer cells.

Hypoxia, which is an important factor that mediates tumor progression and poor treatment response, is particularly associated with tumor chemoresistance. However, the molecular mechanisms underlying hypoxia-induced colorectal cancer chemoresistance remain unclear. The present study aimed to explore the mechanism underlying hypoxia-induced chemotherapy resistance in LOVO colorectal cancer cells. LOVO cells were cultured in a hypoxic environment simulated by cobalt chloride (CoCl2), which is a chemical inducer of hypoxia-inducible factor-1α (HIF-1α). HIF-1α is a transcription factor that has an important role in tumor cell adaptation to hypoxia, and controls the expression of several genes. Various CoCl2 concentrations are often used to simulate degrees of hypoxia. In the present study, following treatment with CoCl2, an MTT assay was conducted to determine the growth and drug sensitivity of LOVO cells. Reverse transcription-polymerase chain reaction and western blotting were used to detect the mRNA and protein expression levels of HIF-1α and factors associated with chemotherapy resistance, including multidrug resistance protein (MRP) and multidrug resistant 1 (MDR1), which encodes the major transmembrane efflux transporter P-glycoprotein (P-gp). In addition, the expression levels of apoptosis-related proteins, including B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax) and Bcl-2-associated agonist of cell death (Bad) were detected by western blotting. Flow cytometry (FCM) was used to visually observe Adriamycin (ADR) accumulation and retention, thus analyzing intracellular drug transportation in cells under hypoxic and normoxic conditions. CoCl2-simulated hypoxia was able to inhibit tumor cell proliferation, and upregulate the expression levels of HIF-1α, MDR1/P-gp and MRP. In addition, proapoptotic members of the Bcl-2 protein family, Bax and Bad, were downregulated. The anti-apoptotic member Bcl-2 exhibited no significant change in expression, whereas the ratio of Bcl-2/Bax was increased. Results of FCM demonstrated that the intracellular retention of ADR was significantly decreased in the hypoxia group cells. In conclusion, the present study revealed that a CoCl2-simulated hypoxic microenvironment was able to effectively induce chemoresistance and reduce apoptosis in LOVO cells.

Effects of autophagy regulation of tumor-associated macrophages on radiosensitivity of colorectal cancer cells.

Tumor‑associated macrophages (TAMs), a major component of the tumor microenvironment, are crucial to the processes of tumor growth, infiltration and metastasis, and contribute to drug resistance. The importance of TAMs in radiation resistance of colorectal cancer remains unclear. To investigate the effects of autophagy regulation of TAMs on the radiosensitivity of colorectal cancer cells, the current study induced TAM formation from THP‑1 monocyte cells. Sequential treatment of THP‑1 cells with PMA for 72 h and human recombinant interleukin‑4 for 24 h was used to stimulate THP‑1 differentiation to TAMs. Expression of the cell surface markers CD68, CD204 and CD206, and changes to cell morphology were used to confirm successful differentiation. The TAMs were stimulated to promote or inhibit autophagy during co‑culture with LoVo colorectal adenocarcinoma cells. The cells were irradiated, with subsequent measurement of LoVo colony formation and apoptosis. Additionally, the expression of p53, Bcl‑2, survivin and Smac proteins was assessed by western blotting. Monodansylcadaverin staining was used to analyze the presence of autophagic vacuoles in TAM, and western blot analysis was used to assess the expression of Beclin‑1, LC3B I and II, ATG‑3, ‑5 and ‑7. The results demonstrated TAM autophagy to be markedly altered by rapamycin and bafilomycin A1 treatment. Following co‑culture with TAMs, the colony formation rate and survival fraction of LoVo cells were significantly higher than those in the control group (P<0.05). It was further demonstrated that the regulation of autophagy in TAMs was able to inhibit the colony formation of LoVo colorectal cancer cells. Upregulation of TAM autophagy using rapamycin exhibited more effective inhibition of LoVo colony formation than autophagy downregulation. Notably, apoptosis was significantly increased in LoVo cells when co‑cultured with TAMs only, or with rapamycin‑mediated autophagy upregulated TAMs, compared with LoVo cells cultured alone (P<0.01). Expression of Bcl‑2, survivin and p53 were reduced in LoVo cells co‑cultured with TAMs, compared with the control group (P<0.05), whereas Smac expression was increased in the co‑culture groups (P<0.01). It was demonstrated that rapamycin‑mediated autophagy stimulation in TAMs led to reduced expression levels of survivin and Bcl‑2, however, Smac expression was increased. The upregulation of autophagy in TAMs inhibited proliferation and induced apoptosis in colon cancer cells, and altered the expression of radiosensitivity‑associated proteins. This data indicated that the radiosensitivity of colorectal cancer cells is associated with autophagy of TAM, and that stimulating TAM autophagy may increase the radiosensitivity of colorectal cancer cells.

Sphingosine kinase 2 promotes colorectal cancer cell proliferation and invasion by enhancing MYC expression.

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers and causes of cancer death in developed countries. SphK2 is overexpressed in a number of aggressive human carcinomas; however, the expression profile and potential function of SphK2 in CRC are still unknown. In this study, we investigated the SphK2 expression in tumoral tissue and the matched normal mucosae using quantitative real-time PCR (qRT-PCR), Western blot, and immunohistochemistry. We also evaluated the impact of SphK2 knockdown on CRC cell proliferation and metastasis in vitro. SphK2 was significantly upregulated in CRC tissue as compared to the matched normal mucosae, and significant overexpression was found in the LoVo CRC cell line. SphK2 depletion by specific small interfering RNA (siRNA) in the CRC cell line was found to affect cell proliferation and cell migration. Our data suggest that the pathogenesis of CRC maybe mediated by SphK2, and SphK2 could represent a selective target for the molecularly targeted treatments of CRC.

Human cytomegalovirus-encoded US28 may act as a tumor promoter in colorectal cancer.

To assess human cytomegalovirus-encoded US28 gene function in colorectal cancer (CRC) pathogenesis. Immunohistochemical analysis was performed to determine US28 expression in 103 CRC patient samples and 98 corresponding adjacent noncancerous samples. Patient data were compared by age, sex, tumor location, histological grade, Dukes' stage, and overall mean survival time. In addition, the US28 gene was transiently transfected into the CRC LOVO cell line, and cell proliferation was assessed using a cell counting kit-8 assay. Cell cycle analysis by flow cytometry and a cell invasion transwell assay were also carried out. US28 levels were clearly higher in CRC tissues (38.8%) than in adjacent noncancerous samples (7.1%) (P = 0.000). Interestingly, elevated US28 amounts in CRC tissues were significantly associated with histological grade, metastasis, Dukes' stage, and overall survival (all P < 0.05); meanwhile, US28 expression was not significantly correlated with age, sex or tumor location. In addition, multivariate Cox regression data revealed US28 level as an independent CRC prognostic marker (P = 0.000). LOVO cells successfully transfected with the US28 gene exhibited higher viability, greater chemotherapy resistance, accelerated cell cycle progression, and increased invasion ability. US28 expression is predictive of poor prognosis and may promote CRC.

CHRNA7 inhibits cell invasion and metastasis of LoVo human colorectal cancer cells through PI3K/Akt signaling.

The α7 neuronal nicotinic receptor gene (CHRNA7) is widely expressed in both the brain and periphery whereas its encoding protein of α7 neuronal acetylcholine receptor (α7nAChR) belongs to the nicotinic acetylcholine receptor family. Considerable evidence suggests that α7nAChR plays an important role in chronic inflammatory and neuropathic pain signaling and thus has been proposed as a potential target for treating cognitive deficits in patients with schizophrenia, attention deficit hyperactivity disorder (ADHD) and Alzheimer's disease. The aim of the present study was to determine the role of endogenous α7nAChR signaling in human colorectal cancer growth and metastasis. pLVX‑CHRNA7 encoding the full length of CHRNA7 was constructed and transfected into LoVo human colorectal cancer cells. Cell proliferation was measured by Cell Counting Kit‑8 (CCK‑8), and cell migration and invasion were detected by Transwell chamber assays. Expression and activity of metastasis‑related metalloproteinases (MMPs) were analyzed by western blotting and gelatin zymography, respectively. Activation of metastasis-related signaling molecules was detected by western blotting. LY294002 was used to specifically block the phosphatidylinositol 3‑kinase/v‑akt murine thymoma viral oncogene homologue (PI3K/Akt) pathway. We showed that concomitantly with an increase in α7nAChR expression after transfection, LoVo cells presented reduced abilities for migration and invasion, which was accompanied by reduced expression levels of MMP‑1 and MMP‑9 as well as activation of the PI3K/Akt signaling pathway. The application of LY294002 restored the migration and invasion abilities of the LoVo cells bearing CHRNA7. Collectively, we conclude that overexpression of CHRNA7 negatively controls colorectal cancer LoVo cell invasion and metastasis via PI3K/Akt pathway activation and may serve as either a diagnostic marker or a therapeutic target for colorectal cancer metastasis.

MicroRNA-143 replenishment re-sensitizes colorectal cancer cells harboring mutant, but not wild-type, KRAS to paclitaxel treatment.

Colorectal cancer (CRC) global incidence is one of the highest among cancers. The KRAS gene has been shown as a robust biomarker for poor prognosis and drug resistance. MicroRNA-143 (miR-143) and let-7 are families of tumor suppressor microRNAs that are often downregulated in CRC, especially with coexistent KRAS mutations. In order to evaluate if miR-143 and/or let-7b replenishment would re-sensitize CRC cells to paclitaxel treatment, we investigated in effect of miR-143 and let-7b replenishments on sensitivity to paclitaxel treatment in KRAS mutant LoVo and wild-type SW48 CRC cell lines. Our results showed that miR-143, but not let-7b, increased sensitization of KRAS mutant tumor cells to paclitaxel. Furthermore, transfection of miR-143, but not let-7b, mimic negatively regulated the expression of mutant but not wild-type KRAS. Combination of miR-143 mimic and paclitaxel induced the onset of apoptosis, and reverted in vitro metastatic properties (migration and invasion) in KRAS mutant tumor cells. MiR-143 thus can be used as a chemosensitizer for the treatment of KRAS mutant tumors and warrants further investigations in in vitro and pre-clinical in vivo models.

MicroRNA-1246 promotes growth and metastasis of colorectal cancer cells involving CCNG2 reduction.

Colorectal cancer (CRC) is the third most common cancer type and the fourth leading cause of cancer‑associated mortality worldwide. MicroRNA (miR)‑1246 is involved in differentiation, invasion, metastasis and chemoresistance of certain types of tumor cells. CCNG2 encodes an unconventional cyclin homolog, cyclin G2 (CycG2), associated with growth inhibition, which correlated significantly with lymph node metastasis, clinical stage, histological grade and poor overall survival in numerous cancer types. To investigate the regulation of miR‑1246 on CycG2 expression, and their effects on proliferation and metastasis of CRC, HCT‑116 and LOVO cells were transfected with pre‑miR‑1246 anti‑miR‑1246 and their negative controls. It was demonstrated that the expression of miR‑1246 was significantly increased in CRC tissues and cell lines, which was the opposite of CycG2. miR‑1246 negatively regulated the expression of CycG2 in HCT‑116 and LOVO CRC cells. CCNG2 is a direct target of miR‑1246 in CRC cells. Overexpression of miR‑1246 induced cell proliferation, migration and invasion, while knockdown of miR‑1246 inhibited proliferation, migration and invasion in the CRC cells. Upregulation of miR‑1246 mediated the malignant progression of CRC and is partly attributed to the downregulation of the expression of CycG2. Consequently, these findings provided a molecular basis for the role of miR‑1246/CCNG2 in the progression of human CRC and suggested a novel target for the treatment of CRC.

Nicotine enhances invasion and metastasis of human colorectal cancer cells through the nicotinic acetylcholine receptor downstream p38 MAPK signaling pathway.

Nicotine as a cigarette component is an established risk factor for colorectal cancer tumorigenesis. The downstream signaling pathways of nicotinic acetylcholine receptors (nAchRs) are believed to be responsible for the cellular effects. In the present study, we evaluated the effects and novel mechanisms for nicotine on the capacity for colorectal cancer cell invasion and metastasis. LOVO and SW620 colorectal cancer cells were stimulated with nicotine in vitro. A Transwell chamber model was applied to detect the capacity for tumor cell invasion. Assays for gelatin zymography and western blotting were applied to detect the activity and expression of metastasis-related matrix metalloproteinases (MMPs), respectively. Signal transduction was assessed by immunoblotting for the phosphorylation of relevant signal molecules and the application of pharmaceutical inhibitors. We showed that nicotine increased LOVO and SW620 colorectal cancer cell invasion along with enhanced activity and expression of MMP-1, -2 and -9. Nicotine increased phosphorylation of p38, ERK, Akt and PI3K p85 but had no effect on phosphorylation of JNK, or NF-κB. Of the pharmaceutical inhibitors of U0126 (ERK1/2 inhibitor), LY294002 (Akt activation inhibitor), SB239063 (p38 MAPK activation inhibitor) and hexamethonium (Hex) (nAchRs inhibitor), the cellular and molecular effects were reduced by the applications of SB239063 and Hex. We concluded that nicotine stimulates the invasion and metastasis of colon cancer cells in vitro via activation of the nAchRs and the p38 MAPK downstream signaling pathway. Therefore, p38 MAPK may have potential as a therapeutic target for smoking-related human colorectal cancer metastasis.

Curcumol Inhibits Growth and Induces Apoptosis of Colorectal Cancer LoVo Cell Line via IGF-1R and p38 MAPK Pathway.

Curcumol, isolated from the traditional medical plant Rhizoma Curcumae, is the bioactive component of Zedoary oil, whose potential anti-tumor effect has attracted considerable attention in recent years. Though many researchers have reported curcumol and its bioactivity, the potential molecular mechanism for its anti-cancer effect in colorectal cancer LoVo cells still remains unclear. In the present study, we found that curcumol showed growth inhibition and induced apoptosis of LoVo cells in a dose- and time-dependent manner. The occurrence of its proliferation inhibition and apoptosis came with suppression of IGF-1R expression, and then increased the phosphorylation of p38 mitogen activated protein kinase (MAPK), which might result in a cascade response by inhibiting the CREB survival pathway and finally triggered Bax/Bcl-2 and poly(ADP-ribose) polymerase 1 (PARP-1) apoptosis signals. Moreover, curcumol inhibited colorectal cancer in xenograft models of nude mice. Immunohistochemical and Western blot analysis revealed that curcumol could decrease the expression of ki-67, Bcl-2 as well as CREB1, and increase the expression of Bax and the phosphorylation of p38, which were consistent with our in vitro study. Overall, our in vitro and in vivo data confirmed the anti-cancer activity of curcumol, which was related to a significant inhibition of IGF-1R and activation of p38 MAPKs, indicating that curcumol may be a potential anti-tumor agent for colorectal carcinoma therapy.

Cryptotanshinone, a Stat3 inhibitor, suppresses colorectal cancer proliferation and growth in vitro.

Cryptotanshinone (CPT) is a natural compound extracted from herbal medicine that has been previously shown to possess antitumor properties in various types of human cancer cells. In the present study, we examined the potential role of CPT in the treatment of colorectal cancer. Using SW480, HCT116, and LOVO colorectal cancer cell lines, the effects of CPT on cell viability, apoptosis, and tumorigenicity were evaluated. The results showed that CPT significantly inhibited the growth and viability of SW480, HCT116, and LOVO cell lines by inducing apoptosis and prevented anchorage dependent growth on agar. In addition, CPT inhibited the activation of Signal transducer and activator of transcription 3 (Stat3) pathways in colorectal cancer cells. Stat3 is a transcription factor that mediates the expression of various genes associated with many cellular processes, such as inflammation and cell growth, and has been shown to promote several cancer types, including colorectal cancer. These findings indicate that CPT may be a potential candidate for the treatment and prevention of colorectal cancer in part by inhibiting the activation of Stat3.

Melatonin induces apoptosis of colorectal cancer cells through HDAC4 nuclear import mediated by CaMKII inactivation.

Melatonin induces apoptosis in many different cancer cell lines, including colorectal cancer. However, the precise mechanisms involved remain largely unresolved. In this study, we provide evidence to reveal a new mechanism by which melatonin induces apoptosis of colorectal cancer LoVo cells. Melatonin at pharmacological concentrations significantly suppressed cell proliferation and induced apoptosis in a dose-dependent manner. The observed apoptosis was accompanied by the melatonin-induced dephosphorylation and nuclear import of histone deacetylase 4 (HDAC4). Pretreatment with a HDAC4-specific siRNA effectively attenuated the melatonin-induced apoptosis, indicating that nuclear localization of HDAC4 is required for melatonin-induced apoptosis. Moreover, constitutively active Ca(2+) /calmodulin-dependent protein kinase II alpha (CaMKIIα) abrogated the melatonin-induced HDAC4 nuclear import and apoptosis of LoVo cells. Furthermore, melatonin decreased H3 acetylation on bcl-2 promoter, leading to a reduction of bcl-2 expression, whereas constitutively active CaMKIIα(T286D) or HDAC4-specific siRNA abrogated the effect of melatonin. In conclusion, the present study provides evidence that melatonin-induced apoptosis in colorectal cancer LoVo cells largely depends on the nuclear import of HDAC4 and subsequent H3 deacetylation via the inactivation of CaMKIIα.

Resveratrol suppresses epithelial-to-mesenchymal transition in colorectal cancer through TGF-β1/Smads signaling pathway mediated Snail/E-cadherin expression.

BackgroundResveratrol extracted from grape has been an ideal alternative drug in the therapy of different cancers including colorectal cancer (CRC). Since the underlying mechanisms of resveratrol on the invasion and metastasis of CRC have not been fully elucidated, and epithelial-to-mesenchymal transition (EMT) is a key process associated with the progression of CRC, here we aimed to investigate the potential mechanism of resveratrol on the inhibition of TGF-β1-induced EMT in CRC LoVo cells.MethodsWe investigated the anticancer effect of resveratrol against LoVo cells in vitro and in vivo. In vivo, the impact of resveratrol on invasion and metastasis was investigated by mice tail vein injection model and mice orthotopic transplantation tumor model. In vivo imaging was applied to observe the lungs metastases, and hemaoxylin-eosin (HE) staining was used to evaluate metastatic lesions. In vitro, impact of resveratrol on the migration and invasion of LoVo cells was evaluated by transwell assay. Inhibition effect of resveratrol on TGF-β-induced EMT was examined by morphological observation. Epithelial phenotype marker E-cadherin and mesenchymal phenotype marker Vimentin were detected by western blot and immunofluorescence. Promoter activity of E-cadherin was measured using a dual-luciferase assay kit. mRNA expression of Snail and E-cadherin was measured by RT-PCR.ResultsWe demonstrated that, resveratrol inhibited the lung metastases of LoVo cells in vivo. In addition, resveratrol reduced the rate of lung metastases and hepatic metastases in mice orthotopic transplantation. In vitro, TGF-β1-induced EMT promoted the invasion and metastasis of CRC, reduced the E-cadherin expression and elevated the Vimentin expression, and activated the TGF-β1/Smads signaling pathway. But resveratrol could inhibit the invasive and migratory ability of LoVo cells in a concentration-dependent manner, increase the expression of E-cadherin, repress the expression of Vimentin, as well as the inhibition of TGF-β1/Smads signaling pathway. Meanwhile, resveratrol reduced the level of EMT-inducing transcription factors Snail and the transcription of E-cadherin during the initiation of TGF-β1-induced EMT.ConclusionsOur new findings provided evidence that, resveratrol could inhibit EMT in CRC through TGF-β1/Smads signaling pathway mediated Snail/E-cadherin expression, and this might the potential mechanism of resveratrol on the inhibition of invasion and metastases in CRC.

The Inhibition by Oxaliplatin, a Platinum-Based Anti-Neoplastic Agent, of the Activity of Intermediate-Conductance Ca2+-Activated K+ Channels in Human Glioma Cells

Oxaliplatin (OXAL) is a third-generation organoplatinum which is effective against advanced cancer cells including glioma cells. How this agent and other related compounds interacts with ion channels in glioma cells is poorly understood. OXAL (100 µM) suppressed the amplitude of whole-cell K⁺ currents (I_K); and, either DCEBIO or ionomycin significantly reversed OXAL-mediated inhibition of I_K in human 13-06-MG glioma cells. In OXAL-treated cells, TRAM-34 did not suppress I_K amplitude in these cells. The intermediate-conductance Ca²⁺-activated K⁺ (IK_Ca) channels subject to activation by DCEBIO and to inhibition by TRAM-34 or clotrimazole were functionally expressed in these cells. Unlike cisplatin, OXAL decreased the probability of IK_Ca-channel openings in a concentration-dependent manner with an IC₅₀ value of 67 µM. No significant change in single-channel conductance of IK_Ca channels in the presence of OXAL was demonstrated. Neither large-conductance Ca²⁺-activated K⁺ channels nor inwardly rectifying K⁺ currents in these cells were affected in the presence of OXAL. OXAL also suppressed the proliferation and migration of 13-06-MG cells in a concentration- and time-dependent manner. OXAL reduced IK_Ca-channel activity in LoVo colorectal cancer cells. Taken together, the inhibition by OXAL of IK_Ca channels would conceivably be an important mechanism through which it acts on the functional activities of glioma cells occurring in vivo.

MiR-1297 regulates the growth, migration and invasion of colorectal cancer cells by targeting cyclo-oxygenase-2.

Cyclo-oxygenase-2(Cox-2), a key regulator of inflammation-producing prostaglandins, promotes cell proliferation and growth. Therefore, a better understanding of the regulatory mechanisms of Cox-2 could lead to novel targeted cancer therapies. MicroRNAs are strongly implicated in colorectal cancer but their specific roles and functions have yet to be fully elucidated. MiR-1297 plays an important role in lung adenocarcinoma and laryngeal squamous cell carcinoma, but its significance in colorectal cancer (CRC) has yet to be reported. In our present study, we found miR-1297 to be down regulated in both CRC-derived cell lines and clinical CRC samples, when compared with normal tissues. Furthermore, miR-1297 could inhibit human colorectal cancer LOVO and HCT116 cell proliferation, migration, and invasion in vitro and tumorigenesis in vivo by targeting Cox-2. Moreover, miR-1297 directly binds to the 3`-UTR of Cox-2, and the expression level was drastically decreased in LOVO and HCT116 cells following overexpression of miR-1297. Additionally, Cox-2 expression levels are inversely correlated with miR-1297 expression in human colorectal cancer xenograft tissues. These results imply that miR-1297 has the potential to provide a new approach to colorectal cancer therapy by directly inhibiting Cox-2 expression.

Expression and clinical significance of miRNA-34a in colorectal cancer.

The aim of this study was to investigate differences of miRNA-34a expression in benign and malignant colorectal lesions. Samples of cancer, paraneoplastic tissues and polyps were selected and total RNA was extracted by conventional methods for real-time PCR to detect the miRNA- 34a expression. In addition, the LOVO colorectal cancer cell line was cultured, treated with the demethylating agent 5-azacytidine and screened for differentially expressed miRNA-34a. After the drug treatment, the miRNA-34a expression of colorectal cancer cell line LOVO was increased and real-time PCR showed that levels of expression in both cell line and colorectal cancer tissues were low, as compared to paraneoplastic tissue (p<0.05). Polyps tissues had significantly higher expression than paraneoplastic and colorectal cancer samples (p<0.05). miRNA-34a-5p may play a role as a tumor suppressor gene in colorectal cancer, with involvement of DNA methylation.

Curcumin partly ameliorates irinotecan-induced diarrhea and synergistically promotes apoptosis in colorectal cancer through mediating oxidative stress

// Da-Jian Zhu 1, 2, * , Yan-Feng Huang 3, * , Xiao-Wu Chen 1 , Zhen-Tao Luo 1 , Guo-Xin Wang 1 , Chang-Chun Liu 1 , Wei-Jie Zhang 1 , Man-Zhao Ouyang 1 1 Department of Gastrointestinal Surgery, Shunde First People’s Hospital Affiliated to Southern Medical University, Guangdong 528300, China 2 Department of Gastrointestinal Surgery, Shunde Women and Children’s Hospital Affiliated to Jinan University, Guangdong 528300, China 3 Department of Traditional Chinese Medicine, Shunde First People’s Hospital Affiliated to Southern Medical University, Guangdong 528300, China * These authors have contributed equally to this work Correspondence to: Xiao-Wu Chen, email: drchenxiaowu@163.com Keywords: curcumin, colorectal cancer, irinotecan, diarrhea, oxidative stress Received: December 07, 2015 Accepted: May 12, 2016 Published: July 14, 2016 ABSTRACT OBJECTIVE: Development of treatment resistance and adverse toxicity limits the gains made by irinotecan in patients with colorectal cancer. According to our previous studies, we found that curcumin could enhance the efficacy of irinotecan-induced apoptosis of colorectal tumor cells in vitro. This study aims to examine the effectiveness of a combination treatment regimen of irinotecan and curcumin in the colorectal cancer xenograft model. RESULTS: Curcumin or irinotecan alone reduced the tumor volume, and the combination had the strongest anticancer effects. Oxidative stress was induced in tumor (MDA: P < 0.01, GPx: P < 0.05, PRDX4: P < 0.01), while was reduced in intestinal tissue (MDA: P < 0.01, SOD: P < 0.05, GPx: P < 0.01). The apoptosis in tumor was accompanied by up-regulation of apoptotic proteins (caspase-3: P < 0.01, Bax: P < 0.01), but down-regulation of anti-apoptotic proteins (pro-caspase-3: P < 0.01, Bcl-2: P < 0.01). Besides, the combination treatment alleviated diarrhea and intestine injury, and also restored the autophagy (PGC-1α: P < 0.05, Atg-7: P < 0.05, and LC3B: P < 0.05) and mitochondrial dynamics (Mfn-1: P < 0.01, Mfn-2: P < 0.01, Drp-1: P < 0.01, Fis-1: P < 0.05) in intestinal tissue. MATERIALS AND METHODS: Nude mice were implanted with LoVo colorectal cancer cells before randomization into the following treatment groups: control; curcumin only; irinotecan only; curcumin + irinotecan. After a 9-day treatment, we compared the tumor weight, tumor volume, morphological change of intestine, and oxidative stress factors (LDH, MDA, SOD, GPx). In addition, we detected the oxidative stress (PRDX4, MnSOD, and p53), apoptosis (Bax, Bcl-2, pro-caspase-3, cleaved-caspase-3) and autophagy (PGC-1α, Atg-7, and LC3B) signaling. CONCLUSIONS: Curcumin could enhance the efficacy of irinotecan-induced apoptosis of colorectal cancer in vivo, while restore the irinotecan-induced autophagy of small intestinal epithelium.

Abstract 5108: The Hsp90 inhibitor ganetespib is a potent chemosensitizer in preclinical colorectal cancer models

Abstract Background: More than half of all individuals diagnosed with colorectal cancer (CRC) will develop metastases and require chemotherapy. These treatments have significantly improved overall patient survival; however, drug resistance is a frequent cause of treatment failure often due to alteration in cell cycle regulators or DNA damage repair. The molecular chaperone HSP90 plays an important role in both processes by stabilizing proteins required for pathway activation and maintenance. Here, we sought to determine if HSP90 inhibition by the investigational drug ganetespib could enhance the activity of standard chemotherapeutics utilized in CRC in order to extend responses and bypass/delay drug resistance. Results: Western blot analyses revealed that low nanomolar ganetespib treatment promoted the degradation of a number of proteins involved in proliferation (EGFR, PDGFR, PI3-K/AKT/p70 S6 kinase, cMET and MAPK), survival (MCL1), anigiogenesis (VEGFR), cell cycle check points and DNA repair (CDK1, CHK1, Survivin, WEE1) in a panel of CRC cell lines. This activity directly correlated with G0/G1 cell cycle arrest and loss of CRC cell viability (average IC50 in 19 CRC cell lines = 43 nM). In vitro combination of ganetespib with conventional chemotherapies (cisplatin, oxaliplatin, 5-FU) augmented the accumulation of DNA damage (phospho-H2AX) and mitotic catastrophe more effectively over monotherapy alone in HCT116, HT29 and LoVo CRC cells. Ganetespib also sensitized CRC cells to ionizing radiation by inducing aberrant mitosis and enhanced DNA damage/fragmentation, resulting in a significant increase in apoptosis. In vivo, ganetespib displayed comparable antitumor activity as capecitabine, cisplatin, and bevacizumab in human CRC tumor xenografts, with treatment/control values of ∼50 indicative of slowly progressive disease. Combining ganetespib with capecitabine resulted in significant tumor regression (T/C = -52, p&amp;lt;0.01). Further, ganetespib improved the tumor suppressive capacity of cisplatin and bevacizumab. Conclusions: The HSP90 inhibitor ganetespib promotes the destabilization of numerous proteins essential for tumor growth and survival as well as those involved in chemotherapeutic resistance. As a result, ganetespib sensitizes colon cancer tumor models to chemotherapy and targeted agents, including VEGF inhibitors. Ganetespib is currently being evaluated in combination with capecitabine and radiation in patients with locally-advanced rectal cancer as part of an open-label, investigator-sponsored Phase 1 clinical study. Citation Format: Suqin He, Don Smith, Manuel Sequeira, John-Paul Jimenez, Chaohua Zhang, Jim Sang, Timothy Korbut, Jaime Acquaviva, Masazumi Nagai, Richard Bates, David A. Proia. The Hsp90 inhibitor ganetespib is a potent chemosensitizer in preclinical colorectal cancer models. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5108. doi:10.1158/1538-7445.AM2014-5108

Abstract 33: In vitro functional study of Ang 2 in colorectal cancer cell line and the significance of Ang 2 expression in colorectal cancer patients

Abstract Objectives: Angiopoietin 2 (Ang-2) is an important regulator of angiogenesis, blood vessel maturation and integrity of the vascular endothelium. The correlation between the dynamic expression of Ang-2 in tumors with regions of high angiogenic activity and a poor prognosis in many tumor types makes Ang-2 an ideal drug target. The function and mechanism of Angiopoietin 2 in colorectal cancer proliferation, invasion, metastasis and angiogenesis have not been fully elucidated to date. The aim of present study was to evaluate the biological roles of Ang-2 in the colorectal cancer cell line and to correlate the Ang-2 overexpression with the clinicopathological factors of colorectal cancers. Methods: The biological roles of Ang-2 were investigated in LoVo colorectal cancer cell line that expresses high level of Ang-2 by knockdown Ang-2 with shRNA transfection. The functional roles of Ang-2 were evaluated by invasion assay, wound healing cell migration assay, MTT assay and tube formation assay. Moreover, Ang-2 expression was investigated by immunohistochemistry on tissue microarrays of 415 cases of colorectal cancer and the association of Ang-2 expression was examined with clinicopathologic features. Results: The LoVo cell line knockdowned Ang-2 by shRNA revealed significant decreases of viability, invasion, migration and tube formation compared to that of control (p&amp;lt;0.005) respectively. The Ang-2 was overexpressed in 45.8% of colorectal cancers. The overexpression of Ang-2 was significantly associated with pT (p=0.048), pN (p&amp;lt;0.001), vascular invasions (p-=0.023), lymphatic invasions (p&amp;lt;0.001) and TNM stages (p=0.022). Multivariate Cox regression analysis showed that the overexpression of Ang-2 in pN stage 1 and 2 were an independent prognostic factor of decreased survival [pN stage 1, HR=5.17 (95% CI: 6.36-19.59, p=0.016); pN stage 2, HR=7.01 (95% CI: 1.76-27.96, p=0.006)]. The overall survival was significantly decreased in patients of Ang-2 high expression [HR=6.78 (95% CI: 4.16-11.05, p&amp;lt;0.001)]. The cumulative survival was significantly decreased in patients of Ang-2 high expression compared to those of Ang-2 low expression by Kaplan-Meier analysis (log rank test, p&amp;lt;0.001). Conclusion: The overexpression of Ang-2 is significantly associated with tumor progression rather than carcinogenesis in colorectal cancer. It can be a valuable poor prognostic marker of colorectal cancer and the Ang-2 can be used in therapeutic strategies. Citation Format: Moo Jun Baek, Dongjun Jeong, Chang-Jin Kim, Tae Hyun Kim, Han Jo Kim, Tae Sung Ahn, Sang Byung Bae, Sang Han Lee. In vitro functional study of Ang 2 in colorectal cancer cell line and the significance of Ang 2 expression in colorectal cancer patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 33. doi:10.1158/1538-7445.AM2014-33