Arginine starvation has the potential to selectively treat both primary tumor and (micro) metastatic tissue with very low side effects. Arginine deiminase (ADI; EC 3.5.3.6), an arginine-degrading enzyme, has been studied as a potential anti-tumor drug for the treatment of arginine-auxotrophic tumors. Though ADI-PEG20 (pegylated ADI by PEG 20,000) already passed the phase I/II clinical trials [1], it is just used as adjuvant therapy because of its low efficiency and less targeting. Then, this paper discussed the efficiency of arginine starvation mediated by ADI expressed in cytoplasm for liver cancers. In order to guarantee the tumor targeting, human telomerase reverse transcriptase (hTERT) promoter was used to drive the expression of ADI in vivo. To access the anti-tumor efficiency of ADI, p53 gene was used as the positive control. Thus, ADI displayed obvious cytotoxicity to BEL7402 and HUH7 cell lines in cytoplasm. The apoptosis rates rose from 15% to nearly 60% after changing the expression vectors from pcDNA4 plasmid to adenovirus. Compared with p53-adenovirus, ADI-adenovirus showed the higher oncolytic activity in the intratumoral injection model of mice. Tumor disappeared after the treatment of ADI-adenovirus for two weeks, and the mice pulled through all. Therefore, ADI is an ideal anti-tumor gene for caner targeting therapy with the help of hTERT promoter.
BackgroundLung adenocarcinoma (LUAD) is a high aggressive human cancer which usually diagnosed at advanced stages. Accumulating evidences indicate that long noncoding RNAs (lncRNAs) are crucial participants in LUAD progression. MethodsThe mRNA levels of LINC00968, miR-22-5p and cell division cycle 14A (CDC14A) were measured using quantitative real-time PCR. Cell proliferation was evaluated using cell counting kit-8 and ow cytometry. Cell migration and cell invasion were assessed by wound healing and transwell assay, respectively. The interactions between LINC00968 and miR-22-5p were validated by RNA immunoprecipitation, RNA pull down and luciferase reporter assay. ResultsWe found that lncRNA LINC00968 was signi cantly down-regulated in LUAD tissues and cell lines.LINC00968 level was positively correlated to survival rate, and negatively correlated to tumor node metastasis stage, tumor size and lymph node metastasis of LUAD patients. LINC00968 over-expression in LUAD cells inhibited cell proliferation and induced cell cycle arrest at G1 phase. LINC00968 overexpression also suppressed migration, invasion and epithelial mesenchymal transition (EMT) as evidenced by elevated E-cadherin, decreased N-cadherin, TWIST and SNAIL levels. We further validated that LINC00968 localized in cytoplasma and acted as an upstream of microRNA miR-22-5p, which was up-regulated in LUAD tissues and cell lines. Besides, elevated miR-22-5p expression abolished the effect of LINC00968 over-expression on LUAD progression including in vivo tumor growth. In addition, we rst validated that cell division cycle 14A (CDC14A), which was down-regulated in LUAD tissues, was a downstream target of miR-22-5p. We over-expressed CDC14A in LUAD cells and miR-22-5p induced LUAD progression was partially reversed. Conclusionour study demonstrated that LINC00968 inhibited proliferation, migration and invasion of LUAD by sponging miR-22-5p and further restoring CDC14A. This novel regulatory network might provide us with promising diagnostic and therapeutic target in LUAD treatment.
Background: Based on its low toxicity, arginine starvation therapy has the potential to cure malignant tumors that cannot be treated surgically. The Arginine deiminase (ADI) gene has been identified to be an ideal cancersuppressor gene. ADI expressed in the cytosol displays higher oncolytic efficiency than ADI-PEG20 (Pegylated Arginine Deiminase by PEG 20,000). However, it is still unknown whether cytosolic ADI has the same mechanism of action as ADI-PEG20 or other underlying cellular mechanisms. Methods: The interactions of ADI with other protein factors were screened by yeast hybrids, and verified by coimmunoprecipitation and immunofluorescent staining. The effect of ADI inhibiting the ferritin light-chain domain (FTL) in mitochondrial damage was evaluated by site-directed mutation and flow cytometry. Control of the mitochondrial apoptosis pathway was analyzed by Western Blotting and real-time PCR experiments. The effect of p53 expression on cancer cells death was assessed by siTP53 transfection. Chromatin autophagy was explored by immunofluorescent staining and Western Blotting. Results: ADI expressed in the cytosol inhibited the activity of cytosolic ferritin by interacting with FTL. The inactive mutant of ADI still induced apoptosis in certain cell lines of ASS-through mitochondrial damage. Arginine starvation also generated an increase in the expression of p53 and p53AIP1, which aggravated the cellular mitochondrial damage. Chromatin autophagy appeared at a later stage of arginine starvation. DNA damage occurred along with the entire arginine starvation process. Histone 3 (H3) was found in autophagosomes, which implies that cancer cells attempted to utilize the arginine present in histones to survive during arginine starvation. Conclusions: Mitochondrial damage is the major mechanism of cell death induced by cytosolic ADI. The process of chromatophagy does not only stimulate cancer cells to utilize histone arginine but also speeds up cancer cell death at a later stage of arginine starvation.
Background : Based on its low toxicity, arginine starvation therapy has the potential to cure malignant tumors that cannot be treated surgically. The Arginine deiminase (ADI) gene has been identified to be an ideal cancer-suppressor gene. ADI expressed in the cytosol displays higher oncolytic efficiency than ADI-PEG20 (Pegylated Arginine Deiminase by PEG 20,000). However, it is still unknown whether cytosolic ADI has the same mechanism of action as ADI-PEG20 or other underlying cellular mechanisms. Methods: The interactions of ADI with other protein factors were screened by yeast hybrids, and verified by co-immunoprecipitation and immunofluorescent staining. The effect of ADI inhibiting the ferritin light-chain domain (FTL) in mitochondrial damage was evaluated by site-directed mutation and flow cytometry. Control of the mitochondrial apoptosis pathway was analyzed by Western Blotting and real-time PCR experiments. The effect of p53 expression on cancer cells death was assessed by siTP53 transfection. Chromatin autophagy was explored by immunofluorescent staining and Western Blotting. Results: ADI expressed in the cytosol inhibited the activity of cytosolic ferritin by interacting with FTL. The inactive mutant of ADI still induced apoptosis in certain cell lines of ASS- through mitochondrial damage. Arginine starvation also generated an increase in the expression of p53 and p53AIP1, which aggravated the cellular mitochondrial damage. Chromatin autophagy appeared at a later stage of arginine starvation. DNA damage occurred along with the entire arginine starvation process. Histone 3 (H3) was found in autophagosomes, which implies that cancer cells attempted to utilize the arginine present in histones to survive during arginine starvation. Conclusions: Mitochondrial damage is the major mechanism of cell death induced by cytosolic ADI. The process of Chromatophagy does not only stimulate cancer cells to utilize histone arginine but also speeds up cancer cell death at a later stage of arginine starvation.
Background Lung adenocarcinoma (LUAD) is a high aggressive human cancer which usually diagnosed at advanced stages. Accumulating evidences indicate that long noncoding RNAs (lncRNAs) are crucial participants in LUAD progression. Methods The mRNA levels of LINC00968, miR-22-5p and cell division cycle 14A (CDC14A) were measured using quantitative real-time PCR. Cell proliferation was evaluated using cell counting kit-8 and flow cytometry. Cell migration and cell invasion were assessed by wound healing and transwell assay, respectively. The interactions between LINC00968 and miR-22-5p were validated by RNA immunoprecipitation, RNA pull down and luciferase reporter assay. Results We found that lncRNA LINC00968 was significantly down-regulated in LUAD tissues and cell lines. LINC00968 level was positively correlated to survival rate, and negatively correlated to tumor node metastasis stage, tumor size and lymph node metastasis of LUAD patients. LINC00968 over-expression in LUAD cells inhibited cell proliferation and induced cell cycle arrest at G1 phase. LINC00968 over-expression also suppressed migration, invasion and epithelial mesenchymal transition (EMT) as evidenced by elevated E-cadherin, decreased N-cadherin, TWIST and SNAIL levels. We further validated that LINC00968 localized in cytoplasma and acted as an upstream of microRNA miR-22-5p, which was up-regulated in LUAD tissues and cell lines. Besides, elevated miR-22-5p expression abolished the effect of LINC00968 over-expression on LUAD progression including in vivo tumor growth. In addition, we first validated that cell division cycle 14A (CDC14A), which was down-regulated in LUAD tissues, was a downstream target of miR-22-5p. We over-expressed CDC14A in LUAD cells and miR-22-5p induced LUAD progression was partially reversed. Conclusion our study demonstrated that LINC00968 inhibited proliferation, migration and invasion of LUAD by sponging miR-22-5p and further restoring CDC14A. This novel regulatory network might provide us with promising diagnostic and therapeutic target in LUAD treatment.
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