Limits...
Targeting a ribonucleoprotein complex containing the caprin-1 protein and the c-Myc mRNA suppresses tumor growth in mice: an identification of a novel oncotarget.

Qiu YQ, Yang CW, Lee YZ, Yang RB, Lee CH, Hsu HY, Chang CC, Lee SJ - Oncotarget (2015)

Bottom Line: Gene expression profiling and gain-of-c-Myc-function experiments also revealed that the downregulated c-Myc contributes to the anti-oncogenic effects of tylophorine compounds.Furthermore, the potent tylophorine derivative dibenzoquinoline-33b elicited a similar effect, as c-Myc protein levels were also decreased in xenograft tumors treated with dibenzoquinoline-33b.Thus, tylophorine compounds exert anti-cancer activity predominantly by targeting and sequestering the caprin-1 protein and c-Myc mRNA associated ribonucleoprotein complex.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli, Taiwan.

ABSTRACT
Tylophorine compounds have been the focus of drug development for decades. Tylophorine derivatives exhibit anti-cancer activities but their cellular targets remain unknown. We used a biotinylated tylophorine derivative to probe for the interacting cellular target(s) of tylophorine. Tylophorine directly binds to caprin-1 and consequently enhances the recruitment of G3BP1, c-Myc mRNA, and cyclin D2 mRNA to form a ribonucleoprotein complex. Subsequently, this tylophorine targeted ribonucleoprotein complex is sequestered to the polysomal fractions and the protein expressions of the associated mRNA-transcripts are repressed. Caprin-1 depleted carcinoma cells become more resistant to tylophorine, associated with decreased formation of the ribonucleoprotein complex targeted by tylophorine. Consequently, tylophorine downregulates c-Myc and cyclins D1/D2, causing hypophosphorylation of Rb and suppression of both processing-body formation and the Warburg effect. Gene expression profiling and gain-of-c-Myc-function experiments also revealed that the downregulated c-Myc contributes to the anti-oncogenic effects of tylophorine compounds. Furthermore, the potent tylophorine derivative dibenzoquinoline-33b elicited a similar effect, as c-Myc protein levels were also decreased in xenograft tumors treated with dibenzoquinoline-33b. Thus, tylophorine compounds exert anti-cancer activity predominantly by targeting and sequestering the caprin-1 protein and c-Myc mRNA associated ribonucleoprotein complex.

Show MeSH

Related in: MedlinePlus

The effects of tylophorine compounds in c-Myc regulated Warburg effect and P-body (processing body) formationA. Tylophorine treatment decreased the protein expressions of GLS1 and LDHA involved in Warburg effect as well as eIF4E and DCP1a in P-body formation. B Ectopically Overexpressed c-Myc restored the protein expressions of GLS1 and LDHA. The relative expression levels of each protein were normalized with their respective internal control GAPDH. C. Tylophorine treatment decreased the formation of P-bodies. The P-bodies were visualized by immunofluorescent staining using anti-Dcp1a-TRITC (in red) and eIF4E-FITC (in green). DAPI (in blue) was used for nuclear counterstaining. The carcinoma cells were treated with DMSO, tylophorine (2 μM), or nocodazole (30 ng/mL) for 24 h prior to western blotting or immunofluorescent staining analyses with the indicated antibodies. The percentage of the cell population exhibiting P-bodies and the relative percentages of the total number of P-bodies in each treatment were counted with Image-J software (National Institutes of Health) and listed. Nocodazole was used an additional compound control that induces formation of P-bodies. The results shown are representative of 3 independent experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4385842&req=5

Figure 5: The effects of tylophorine compounds in c-Myc regulated Warburg effect and P-body (processing body) formationA. Tylophorine treatment decreased the protein expressions of GLS1 and LDHA involved in Warburg effect as well as eIF4E and DCP1a in P-body formation. B Ectopically Overexpressed c-Myc restored the protein expressions of GLS1 and LDHA. The relative expression levels of each protein were normalized with their respective internal control GAPDH. C. Tylophorine treatment decreased the formation of P-bodies. The P-bodies were visualized by immunofluorescent staining using anti-Dcp1a-TRITC (in red) and eIF4E-FITC (in green). DAPI (in blue) was used for nuclear counterstaining. The carcinoma cells were treated with DMSO, tylophorine (2 μM), or nocodazole (30 ng/mL) for 24 h prior to western blotting or immunofluorescent staining analyses with the indicated antibodies. The percentage of the cell population exhibiting P-bodies and the relative percentages of the total number of P-bodies in each treatment were counted with Image-J software (National Institutes of Health) and listed. Nocodazole was used an additional compound control that induces formation of P-bodies. The results shown are representative of 3 independent experiments.

Mentions: Although most tylophorine-treated cells were viable, their proliferation was completely suppressed [20], and no significant apoptosis occurred [25]. Therefore, we examined the effect of tylophorine treatment on GLS1 (Glutaminase type 1) [3] and LDHA (Lactate dehydrogenase) [2], c-Myc-targeted genes that mediate the cancer cell nutrient supply via the Warburg effect, and observed that the protein expression levels of these genes were downregulated in tylophorine-treated carcinoma cells (Fig. 5A and 5B). When c-Myc was overexpressed in tylophorine-treated HONE-1 cells, the protein expression levels of GLS1 and LDHA were restored (Fig. 5B). Thus, tylophorine downregulated the Warburg effect by suppressing c-Myc protein expression levels.


Targeting a ribonucleoprotein complex containing the caprin-1 protein and the c-Myc mRNA suppresses tumor growth in mice: an identification of a novel oncotarget.

Qiu YQ, Yang CW, Lee YZ, Yang RB, Lee CH, Hsu HY, Chang CC, Lee SJ - Oncotarget (2015)

The effects of tylophorine compounds in c-Myc regulated Warburg effect and P-body (processing body) formationA. Tylophorine treatment decreased the protein expressions of GLS1 and LDHA involved in Warburg effect as well as eIF4E and DCP1a in P-body formation. B Ectopically Overexpressed c-Myc restored the protein expressions of GLS1 and LDHA. The relative expression levels of each protein were normalized with their respective internal control GAPDH. C. Tylophorine treatment decreased the formation of P-bodies. The P-bodies were visualized by immunofluorescent staining using anti-Dcp1a-TRITC (in red) and eIF4E-FITC (in green). DAPI (in blue) was used for nuclear counterstaining. The carcinoma cells were treated with DMSO, tylophorine (2 μM), or nocodazole (30 ng/mL) for 24 h prior to western blotting or immunofluorescent staining analyses with the indicated antibodies. The percentage of the cell population exhibiting P-bodies and the relative percentages of the total number of P-bodies in each treatment were counted with Image-J software (National Institutes of Health) and listed. Nocodazole was used an additional compound control that induces formation of P-bodies. The results shown are representative of 3 independent experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385842&req=5

Figure 5: The effects of tylophorine compounds in c-Myc regulated Warburg effect and P-body (processing body) formationA. Tylophorine treatment decreased the protein expressions of GLS1 and LDHA involved in Warburg effect as well as eIF4E and DCP1a in P-body formation. B Ectopically Overexpressed c-Myc restored the protein expressions of GLS1 and LDHA. The relative expression levels of each protein were normalized with their respective internal control GAPDH. C. Tylophorine treatment decreased the formation of P-bodies. The P-bodies were visualized by immunofluorescent staining using anti-Dcp1a-TRITC (in red) and eIF4E-FITC (in green). DAPI (in blue) was used for nuclear counterstaining. The carcinoma cells were treated with DMSO, tylophorine (2 μM), or nocodazole (30 ng/mL) for 24 h prior to western blotting or immunofluorescent staining analyses with the indicated antibodies. The percentage of the cell population exhibiting P-bodies and the relative percentages of the total number of P-bodies in each treatment were counted with Image-J software (National Institutes of Health) and listed. Nocodazole was used an additional compound control that induces formation of P-bodies. The results shown are representative of 3 independent experiments.
Mentions: Although most tylophorine-treated cells were viable, their proliferation was completely suppressed [20], and no significant apoptosis occurred [25]. Therefore, we examined the effect of tylophorine treatment on GLS1 (Glutaminase type 1) [3] and LDHA (Lactate dehydrogenase) [2], c-Myc-targeted genes that mediate the cancer cell nutrient supply via the Warburg effect, and observed that the protein expression levels of these genes were downregulated in tylophorine-treated carcinoma cells (Fig. 5A and 5B). When c-Myc was overexpressed in tylophorine-treated HONE-1 cells, the protein expression levels of GLS1 and LDHA were restored (Fig. 5B). Thus, tylophorine downregulated the Warburg effect by suppressing c-Myc protein expression levels.

Bottom Line: Gene expression profiling and gain-of-c-Myc-function experiments also revealed that the downregulated c-Myc contributes to the anti-oncogenic effects of tylophorine compounds.Furthermore, the potent tylophorine derivative dibenzoquinoline-33b elicited a similar effect, as c-Myc protein levels were also decreased in xenograft tumors treated with dibenzoquinoline-33b.Thus, tylophorine compounds exert anti-cancer activity predominantly by targeting and sequestering the caprin-1 protein and c-Myc mRNA associated ribonucleoprotein complex.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli, Taiwan.

ABSTRACT
Tylophorine compounds have been the focus of drug development for decades. Tylophorine derivatives exhibit anti-cancer activities but their cellular targets remain unknown. We used a biotinylated tylophorine derivative to probe for the interacting cellular target(s) of tylophorine. Tylophorine directly binds to caprin-1 and consequently enhances the recruitment of G3BP1, c-Myc mRNA, and cyclin D2 mRNA to form a ribonucleoprotein complex. Subsequently, this tylophorine targeted ribonucleoprotein complex is sequestered to the polysomal fractions and the protein expressions of the associated mRNA-transcripts are repressed. Caprin-1 depleted carcinoma cells become more resistant to tylophorine, associated with decreased formation of the ribonucleoprotein complex targeted by tylophorine. Consequently, tylophorine downregulates c-Myc and cyclins D1/D2, causing hypophosphorylation of Rb and suppression of both processing-body formation and the Warburg effect. Gene expression profiling and gain-of-c-Myc-function experiments also revealed that the downregulated c-Myc contributes to the anti-oncogenic effects of tylophorine compounds. Furthermore, the potent tylophorine derivative dibenzoquinoline-33b elicited a similar effect, as c-Myc protein levels were also decreased in xenograft tumors treated with dibenzoquinoline-33b. Thus, tylophorine compounds exert anti-cancer activity predominantly by targeting and sequestering the caprin-1 protein and c-Myc mRNA associated ribonucleoprotein complex.

Show MeSH
Related in: MedlinePlus