scholarly journals Epigenetic regulation of osteopontin splicing isoform c defines its role as a microenvironmental factor to promote the survival of colon cancer cells from 5-FU treatment

2020 ◽  
Author(s):  
Siyuan Chang ◽  
Jing Huang ◽  
Huan Niu ◽  
Jing Wang ◽  
Yang Si ◽  
...  

Abstract Background: Drug resistance to 5-fluorouracil (5-FU) and recurrence after chemotherapy in colorectal cancer remain a challenge to be resolved for the improvement of patient outcomes. It is recognized that a variety of secretory proteins released from the tumor cells exposed to chemo-drugsinto the tumor microenvironment (TME) contributedto the cell-to-cell communication, and altered the drug sensitivity.One of these important factors is osteopontin (OPN), which exists in several functional forms from alternative splicing and post-translational processing. In colon cancer cells, increased total OPN expression was observed during the progression of tumors, however, the exact role and regulation of the OPN splicing isoforms was not well understood. Methods: We assayed precisely the abundance of majorOPN splicing isoformsunder5-FU treatmentsincolon cancer cell lineswith different sensitivities to 5-FU, and also evaluated the effects of the condition medium from OPNsplicing isoforms overexpressed cells on cell functions. The methods of nuclear calcium reporter assays and ChIP (chromatin immunoprecipitation) assays were used to investigate the molecular mechanism underlining the production of OPN isoforms.Results: We discovered that OPNc was a most increased splicing isoform to a significant abundance following 5-FU treatment of colon cancer cells. OPNc as a secretory protein in the conditioned medium exerted a more potent effect to promote cell survival in 5-FU than other OPN isoforms. The kinetic response of nuclear calcium signalscouldbe used to indicate an immediate effect of the conditioned medium containing OPNc and other isoforms. MeCP2 was identified to regulate the splicing of opn gene, where the phosphorylation of MeCP2 at S421 site, possibly by CAMKII, was required. Conclusions: The results demonstrated that the production of OPNc was highly controlled under epigenetic regulations, where MeCP2 and the activation of nuclear calcium signaling were involved. It was also suggested that OPNc could transmit the stress signal of cells upon chemotherapy in TME and promoted the survival of adjacent colon cancer cells.

2020 ◽  
Author(s):  
Siyuan Chang ◽  
Jing Huang ◽  
Huan Niu ◽  
Jing Wang ◽  
Yang Si ◽  
...  

Abstract Background: Drug resistance to 5-fluorouracil (5-FU) and recurrence after chemotherapy in colorectal cancer remain a challenge to be resolved for the improvement of patient outcomes. It is recognized that a variety of secretory proteins released from the tumor cells exposed to chemo-drugs into the tumor microenvironment (TME) contributed to the cell-to-cell communication, and altered the drug sensitivity. One of these important factors is osteopontin (OPN), which exists in several functional forms from alternative splicing and post-translational processing. In colon cancer cells, increased total OPN expression was observed during the progression of tumors, however, the exact role and regulation of the OPN splicing isoforms was not well understood.Methods: We assayed precisely the abundance of major OPN splicing isoforms under 5-FU treatments in colon cancer cell lines with different sensitivities to 5-FU, and also evaluated the effects of the condition medium from OPN splicing isoforms overexpressed cells on cell functions. The methods of nuclear calcium reporter assays and ChIP (chromatin immunoprecipitation) assays were used to investigate the molecular mechanism underlining the production of OPN isoforms.Results: We discovered that OPNc was a most increased splicing isoform to a significant abundance following 5-FU treatment of colon cancer cells. OPNc as a secretory protein in the conditioned medium exerted a more potent effect to promote cell survival in 5-FU than other OPN isoforms. The kinetic response of nuclear calcium signals could be used to indicate an immediate effect of the conditioned medium containing OPNc and other isoforms. Methyl-CpG binding protein 2 (MeCP2) was identified to regulate the splicing of opn gene, where the phosphorylation of MeCP2 at S421 site, possibly by calmodulin dependent protein kinase II (CaMKII) was required.Conclusions: The results demonstrated that the production of OPNc was highly controlled under epigenetic regulations, where MeCP2 and the activation of nuclear calcium signaling were involved. It was also suggested that OPNc could transmit the stress signal of cells upon chemotherapy in TME and promoted the survival of adjacent colon cancer cells.


2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Siyuan Chang ◽  
Jing Huang ◽  
Huan Niu ◽  
Jing Wang ◽  
Yang Si ◽  
...  

Abstract Background Drug resistance to 5-fluorouracil (5-FU) and recurrence after chemotherapy in colorectal cancer remain a challenge to be resolved for the improvement of patient outcomes. It is recognized that a variety of secretory proteins released from the tumor cells exposed to chemo-drugs into the tumor microenvironment (TME) contributed to the cell-to-cell communication, and altered the drug sensitivity. One of these important factors is osteopontin (OPN), which exists in several functional forms from alternative splicing and post-translational processing. In colon cancer cells, increased total OPN expression was observed during the progression of tumors, however, the exact role and regulation of the OPN splicing isoforms was not well understood. Methods We assayed precisely the abundance of major OPN splicing isoforms under 5-FU treatments in colon cancer cell lines with different sensitivities to 5-FU, and also evaluated the effects of the condition medium from OPN splicing isoforms overexpressed cells on cell functions. The methods of nuclear calcium reporter assays and ChIP (chromatin immunoprecipitation) assays were used to investigate the molecular mechanism underlining the production of OPN isoforms. Results We discovered that OPNc was a most increased splicing isoform to a significant abundance following 5-FU treatment of colon cancer cells. OPNc as a secretory protein in the conditioned medium exerted a more potent effect to promote cell survival in 5-FU than other OPN isoforms. The kinetic response of nuclear calcium signals could be used to indicate an immediate effect of the conditioned medium containing OPNc and other isoforms. Methyl-CpG binding protein 2 (MeCP2) was identified to regulate the splicing of opn gene, where the phosphorylation of MeCP2 at S421 site, possibly by calmodulin dependent protein kinase II (CaMKII) was required. Conclusions The results demonstrated that the production of OPNc was highly controlled under epigenetic regulations, where MeCP2 and the activation of nuclear calcium signaling were involved. It was also suggested that OPNc could transmit the stress signal of cells upon chemotherapy in TME and promoted the survival of adjacent colon cancer cells.


2021 ◽  
Author(s):  
Huan Niu ◽  
Meng Zhao ◽  
Jing Huang ◽  
Jing Wang ◽  
Yang Si ◽  
...  

Abstract Background: Resistance to 5-fluorouracil (5-FU) in chemotherapy and recurrence of colorectal tumors is a serious problem to be resolved for the improvement of clinical outcomes.Methods: In the present study, the effects of conditioned medium (CM) derived from 5-FU-resistant HCT-8/FU on cell functions were evaluated. The methods of immunofluorescence and RNA-seq analyses were used to investigate the molecular mechanism underlining the roles of CM from resistant cells.Results: we found that CM derived from 5-FU-resistant HCT-8/FU was able to reduce 5-FU chemosensitivity of HCT-8 colon cancer cells, with correlating changes in the number and morphology of the Cajal bodies (CBs) as observable nuclear structures. We identified UHMK1 was able to change the disassembly and reassembly of CBs regulated by the phosphorylation of coilin, a major component of CBs, and subsequently resulted in a large number of variations of RNA alternative splicing, affecting the cell survival following 5-FU treatment through changes in intracellular phenotype and transmitted preadaptive signals to adjacent cells in tumor microenvironment (TME).Conclusion: Our finding provided evidence to demonstrate CBs of their disassembling/reassembling dynamics to indicate drug sensitivity or resistance in tumor cells in response to stress signal. The results also suggested that UHMK1 could be an important factor to maintain CB structure and morphology with its possible roles in the regulation of splicing events, especially when cells exposed to cytotoxic drugs.


2001 ◽  
Vol 120 (5) ◽  
pp. A493-A493
Author(s):  
J HARDWICK ◽  
G VANDENBRINK ◽  
S VANDEVENTER ◽  
M PEPPELENBOSCH

Endoscopy ◽  
2005 ◽  
Vol 37 (05) ◽  
Author(s):  
GA Doherty ◽  
SM Byrne ◽  
SC Austin ◽  
GM Scully ◽  
EW Kay ◽  
...  

Author(s):  
Mayson H. Alkhatib ◽  
Dalal Al-Saedi ◽  
Wadiah S. Backer

The combination of anticancer drugs in nanoparticles has great potential as a promising strategy to maximize efficacies by eradicating resistant, reduce the dosage of the drug and minimize toxicities on the normal cells. Gemcitabine (GEM), a nucleoside analogue, and atorvastatin (ATV), a cholesterol lowering agent, have shown anticancer effect with some limitations. The objective of this in vitro study was to evaluate the antitumor activity of the combination therapy of GEM and ATVencapsulated in a microemulsion (ME) formulation in the HCT116 colon cancer cells. The cytotoxicity and efficacy of the formulation were assessed by the 3- (4,5dimethylthiazole-2-yl)-2,5-diphyneltetrazolium bromide (MTT) assay. The mechanism of cell death was examined by observing the morphological changes of treated cells under light microscope, identifying apoptosis by using the ApopNexin apoptosis detection kit, and viewing the morphological changes in the chromatin structure stained with 4′,6-diamidino-2-phenylindole (DAPI) under the inverted fluorescence microscope. It has been found that reducing the concentration of GEM loaded on ME (GEM-ME) from 5μM to 1.67μM by combining it with 3.33μM of ATV in a ME formulation (GEM/2ATV-ME) has preserved the strong cytotoxicity of GEM-ME against HCT116 cells. The current study proved that formulating GEM with ATV in ME has improved the therapeutic potential of GEM and ATV as anticancer drugs.


Sign in / Sign up

Export Citation Format

Share Document