Tubb3 regulation by the Erk and Akt signaling pathways: a mechanism involved in the effect of arginine ADP-ribosyltransferase 1 (Art1) on apoptosis of colon carcinoma CT26 cells.

The influence of the most important classical mono-ADP-ribosyltransferase, arginine ADP-ribosyltransferase 1 (Art1), on survival and apoptosis of colon carcinoma cells and the potential mechanisms have been partly discussed in our previous study but still need to be further studied. In this present study, Art1 of colon carcinoma CT26 cells was silenced with lentiviral vector-mediated short hairpin RNA (shRNA) or overexpressed with lentiviral vector-mediated complementary DNA (cDNA) and allograft transplant tumors are established in Balb/c mice. We verified Art1 knockdown increases apoptosis of CT26 cells transplant tumor; Art1 overexpression acts oppositely. Accordingly, growth of transplant tumors is inhibited in Art1 knockdown transplant tumors and increases in Art1 overexpression transplant tumors. Furthermore, activity of Akt and Erk cell signal pathways and expression of an apoptosis biomarker, ßIII-tubulin (Tubb3), decrease when Art1 was silenced and increase when Art1 was overexpressed. Inhibiting Akt pathway or Erk pathway both downregulates expression of Tubb3 on protein and messenger RNA (mRNA) level, indicating that Tubb3 could be regulated by both Akt and Erk pathways, and plays a role in the influence of Art1 on apoptosis of Balb/c mice allograft transplant tumor. We also demonstrated that Bcl-2 family is not the responsible downstream factor of the Erk pathway in colon carcinoma cells which is undergoing apoptosis. These findings enrich the molecular mechanism for the function of Art1 in colon carcinoma and provide a complementary support for Art1 to be a potential therapeutic target of the treatment of this kind of malignant tumor.

Determination of Carbon Dioxide in Refined Titanium Tetrachloride by Infrared Spectroscopy.

Refined TiCl4 is the key procedure in producing titanium sponge. Besides, the content of carbon and oxygen (C and O) impurities in titanium sponge and that of C and O impurities in refined TiCl4 presents the 4-times enrichment relationship. Therefore, the content control of the C and O impurities in refined TiCl4 becomes the key part for the quality control of titanium material. In order to control the oxygen and carbon, there is the need to analyze the source of C and O impurities so that strict control can be conducted over the impurities of refined TiCl4. Determination of CO2 in refined TiCl4 was significant for analysis of its impurities. CO2 could be determined by infrared spectroscopy due to its infrared characteristic spectrum line. However, normal infrared absorption cell was not fit for the sample analysis, because TiCl4 easily reacted with moisture in the air and immediately was hydrolyzed to form highly corrosive hydrochloric acid smoke. According to Lambert-Beer Law, which means the concentration (c(ξ)) and absorbance(A) - length (L) curve's slope have direct ratio. The infrared absorption cell with the window film of ZnSe (φ10 mm x 1 mm, wavenumers: 7 800 -440 cm(-1)) and the glass cell (optical path: 42, 22, 12, 7 and 4 mm) was assembled and utilized in determination of the CO2 in refined TiCl4 by standard addition method. The detection limit of CO2 was 0.92 mg x kg(-1), the regression equation was Y = 0.031 1X, R = 0.997 2; With standard addition method, the regression equation of CO2 was Y = 0.131 7X, R = 0.998 6, it's good in linearity relation, the CO2 content in refined TiCl4 is determined to be 1.53 mg x kg(-1) and SD up to 0.04 x mg x kg(-1). RSD of the method precision is between 0.53%-1.27%, while recovery rate is between 89.2%-96.8%. This infrared absorption device was safe, simple and convenient, easily removable and washable, and re-useable. The method could conduct the quantitative analysis over the CO2 content in refined TiCl4 through adding standard sample for one time, it could meet the requirement of determination of CO2 in refined TiCl4.

[A Set of Infrared Cells for the Determination of Titanium Oxychloride in Refined Titanium Tetrachloride].

The content control of the impurities in refined TiCl4 becomes the key part for the quality control of titanium material. Refined TiCl4 is the key procedure in producing titanium sponge. Besides, the content of the impurities in titanium sponge and that of the impurities in refined TiCl4 presents the 4-times enrichment relationship. Therefore, control the content of the oxygen, there is the need to analyze the source of oxygen impurities so that strict control can be conducted over the impurities of refined TiCl4. Determination of TiOCl2 in refined TiCl4 was significant for analysis of its impurities. TiOCl2 could be determined by infrared spectroscopy due to its infrared characteristic spectrum line. However, normal infrared absorption cell was not fit for the sample analysis, because TiCl4 easily reacted with moisture in the air and immediately was hydrolyzed to form highly corrosive hydrochloric acid smoke. According to Lambert-Beer Law, which means the concentration (c(x)) and absorbance (A)-length (L) curve's slope have direct ratio. The infrared absorption cell with the window film of ZnSe (Φ10 x 1 mm, wavenumers: 7800-440 cm⁻¹) and the glass cell (optical path: 22, 12, 7 and 4 mm) was assembled and utilized in determination of the TiOCl2 in refined TiCl4 by standard addition method. The detection limit of TiOCl2 was 17.8 mg · kg⁻¹, the regression equation was Y = 1.011 8X, R = 0.9963; With standard addition method, the regression equation of TiOCl2 was Y = 1.940 0X, R = 0.997 0, it' s good in linearity relation, the TiOCl2 content in refined TiCl4 is determined to be 833.8 mg · kg⁻¹ and SD up to 40.0 mg · kg⁻¹. RSD of the method precision is between 0.95%-1.94%, while recovery rate is between 88.5%-93.1%. This infrared absorption device was safe, simple and convenient, easily removable and washable, and re-useable. The method could conduct the quantitative analysis over the TiOCl2 content in refined TiCl4 through adding standard sample for one time, it could meet the requirement of determination of TiOCl2 in refined TiCl4.

ART1 silencing enhances apoptosis of mouse CT26 cells via the PI3K/Akt/NF-κB pathway.

BACKGROUND/AIMS: Colorectal carcinoma is one of the most common cancers world-wide, with high morbidity and mortality rates. Arginine ADP-ribosyltransferase 1(ART1) is an important ecto-ADP-ribose transferase and has been proven to be intimately involved in a number of biological processes. However, the influence of ART1 on survival and apoptosis of colorectal carcinoma cells and the potential mechanism of action of ART1 remain uncharacterized. METHODS: ART1 was silenced via lentiviral vector-mediated short hairpin RNA (shRNA) in CT26 colon carcinoma cells, and cisplatin (CDDP) was applied to induce apoptosis. Survival and apoptosis rate of CT26 cells was assessed by CCK8 assay, flow cytometry and Hoechst 33342 staining. Expression and activity of signaling proteins were detected by Western blot. RESULTS: ART1 knockdown enhanced the inhibition of cell survival and increased the apoptosis induced by CDDP. Furthermore, the reduced survival rate correlated with reduced levels of phos-Akt(Thr308) and phos-IκBα and reduced NF-κB p65 nuclear translocation. A decline in Bcl-2 and Bcl-xl expression and an increase in Bax expression may explain the enhanced apoptosis. CONCLUSION: This study provides a molecular mechanism for the function of ART1 in colorectal carcinoma and defines a potential therapeutic target for the enhanced treatment of this prominent world-wide disease.

MiR-130a-3p suppresses colorectal cancer growth by targeting Wnt Family Member 1 (WNT1).

The microRNA miR-130a-3p (miR-130a-3p) has anti-tumor activity against numerous cancer types. Further, miR-130a-3p may target Wnt signaling, which is a critical pathway regulating tumorigenesis. Functions of miR-130a-3p in colorectal cancer (CRC) and contributions of Wnt1 pathway modulation, however, have not been examined, hence the exploration on these two aspects. In this study, in comparison with normal controls, both CRC tissue and multiple CRC cell lines showed downregulated miR-130a-3p. MiR-130a-3p overexpression contributed to a decrease in CRC cell proliferation. Additionally, its overexpression also caused reduced expression of WNT Family Member 1 (WNT1) and downstream WNT pathway factors c-myc and cyclin D1. Dual-luciferase assay revealed WNT1 as a direct target of miR-130a-3p, and further the inhibitory effect of miR-130a-3p on c-myc and cyclin D1 was proved to be reversed by overexpressed WNT1. Collectively, miR-130a-3p inhibits CRC growth by directly targeting WNT1, and miR-130a-3p and WNT1 pathway-associated factors are defined as potential targets for CRC treatment.

Effect of ART1 on the proliferation and migration of mouse colon carcinoma CT26 cells in vivo.

Arginine-specific mono-ADP-ribosyltransferase 1 (ART1) is an important enzyme that catalyzes arginine-specific mono­ADP­ribosylation. There is evidence that arginine­specific mono­ADP­ribosylation may affect the proliferation of smooth muscle cells via the Rho­dependent signaling pathway. Previous studies have demonstrated that ART1 may have a role in the proliferation, invasion and apoptosis of colon carcinoma in vitro. However, the effect of ART1 on the proliferation and invasion of colon carcinoma in vivo has yet to be elucidated. In the present study, mouse colon carcinoma CT26 cells were infected with a lentivirus to produce ART1 gene silencing or overexpression, and were then subcutaneously transplanted. To observe the effect of ART1 on tumor growth or liver metastasis in vivo, a spleen transplant tumor model of CT26 cells in BALB/c mice was successfully constructed. Expression levels of focal adhesion kinase (FAK), Ras homolog gene family member A (RhoA) and the downstream factors, c­myc, c­fos and cyclooxygenase­2 (COX­2) proteins, were measured in vivo. The results demonstrated that ART1 gene silencing inhibited the growth of the spleen transplanted tumor and its ability to spread to the liver via metastasis. There was also an accompanying increase in expression of FAK, RhoA, c­myc, c­fos and COX­2, whereas CT26 cells with ART1 overexpression demonstrated the opposite effect. These results suggest a potential role for ART1 in the proliferation and invasion of CT26 cells and a possible mechanism in vivo.

Regulation of the RhoA/ROCK/AKT/ß-catenin pathway by arginine-specific ADP-ribosytransferases 1 promotes migration and epithelial-mesenchymal transition in colon carcinoma.

Arginine-specific ADP-ribosytransferases 1 (ART1) is able to modify the arginine of specific proteins by mono-ADP-ribosylation. We previously reported that the expression of ART1 in human colon adenocarcinoma tissues was higher than in adjacent tissues. Herein, we primarily revealed that ART1 could regulate the epithelial-mesenchymal transition (EMT) and, therefore, the development of colon carcinoma. In CT26 cells, which overexpressed ART1 by lentiviral transfection, the following were promoted: alterations of spindle-like non-polarization, expression of EMT inducers and mesenchymal markers, migration, invasion and adhesion. However, epithelial marker expression was decreased. Correspondingly, knockdown of ART1 in CT26 cells had the opposite effects. The effect of ART1 on EMT and carcinoma metastasis was also verified in a liver metastasis model of BALB/c mice. To further explore the molecular mechanism of ART1 in EMT, CT26 cells were treated with several specific inhibitors and gene silencing. Our data suggest that ART1 could regulate EMT by regulating the RhoA/ROCK1/AKT/ß-catenin pathway and its downstream factors (snail1, vimentin, N-cadherin and E-cadherin) and that it therefore plays an important role in the progression of colon carcinoma.

ART1 promotes starvation-induced autophagy: a possible protective role in the development of colon carcinoma.

Autophagy plays a protective role in colorectal carcinoma. Arginine ADP-ribosyltransferase 1 (ART1) is an important mono-ADP-ribose transferase, which has been shown to play a role in biological processes such as proliferation and invasion of cancer cells. Interestingly, the role of ART1 in the regulation of autophagy is still not clear. We examined effects of overexpression or knockdown of ART1 by lentiviral transfection on starvation-induced autophagy of colon carcinoma CT26 cell lines in vivo and in vitro. The formation of autophagosome was detected by electron microscopy, acridine orange staining and expression of LC3 B. The molecular contributions of ART1 in regulation of autophagy were detected by western blotting or by co-immunoprecipitation. Additionally, inhibitors were used to study further the signaling pathway of ART1 in the regulation of autophagy. CCK8 assay, plate cloning assay, soft agar assay, examination of subcutaneous transplanted carcinoma in BALB/c mice, flow cytometry and Hoechst33342 staining were used to assess survival and apoptotic ability when starvation-induced autophagy modulated by ART1 was inhibited by 3-MA. Overexpression of ART1 promoted starvation-induced autophagy, which related to increases in the expression of Rac1, NF-κB, PARP-1, LKB1 and p-AMPK and a decrease in the expression of p-P70S6K. Correspondingly, knockdown of ART1 caused the opposite effects. ART1 also interacted with integrin α7. Additionally, changes of protein expressions were further validated following inhibition of Rac1 and PARP-1 in the starvation-induced ART1-GFP CT26 cells. Inhibition of ART1-stimulated starvation-induced autophagy restrained the growth and promoted apoptosis. ART1 is thus relevant in starvation-induced autophagy in colorectal carcinoma and may play essential roles in therapeutic anticancer strategies.

Synergistic effect of arginine-specific ADP-ribosyltransferase 1 and poly(ADP-ribose) polymerase-1 on apoptosis induced by cisplatin in CT26 cells.

Arginine-specific ADP-ribosyltransferase 1 (ART1) and poly(ADP-ribose) polymerase-1 (PARP-1) are both post­translational modification proteins. Inhibition of PARP1 induces apoptosis in cancer cells, and ART1 regulates RhoA which promotes apoptosis in hepatic cancer cells when inhibited. However, the interaction of ART1 and PARP-1 on the effect of apoptosis has not yet been elucidated. In the present study, lentiviral vector-mediated ART1-cDNA was transfected into CT26 cells, and the apoptosis rate was detected by flow cytometric assay and Hoechst 33342 staining. Relevant factors were detected by reverse transcriptase-PCR and western blotting. The results showed that the apoptosis rate in the ART1-cDNA CT26 cells treated with PARP-1 inhibitor 5-aminoisoquinoline (5-AIQ) and cisplatin increased, when compared with the ART1-cDNA CT26 cells treated with cisplatin only or the untreated ART1-cDNA CT26 cells. Further studies have shown that PARP-1 is in the downstream of ART1, and plays a role in ART1-mediated CT26 cell apoptosis through the ROCK1/NF-κB/PARP-1 pathway when induced by cisplatin. We also found that in cisplatin-treated cells, activated caspase 3 cleaved PARP-1 and the decreased level of PARP-1 in turn decreased the expression of nuclear factor (NF)-κB, Cox-2 and increased caspase 3, resulting in the enhanced ability of ART1 to regulate CT26 cell apoptosis. Our research provides initial sight into the synergistic effect of ART1 and PARP-1 on apoptosis induced by cisplatin in murine colon carcinoma CT26 cells.