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Repression of c-Kit by p53 is mediated by miR-34 and is associated with reduced chemoresistance, migration and stemness.

Siemens H, Jackstadt R, Kaller M, Hermeking H - Oncotarget (2013)

Bottom Line: The c-Kit receptor tyrosine kinase is commonly over-expressed in different types of cancer. p53 activation is known to result in the down-regulation of c-Kit.Taken together, our data establish c-Kit as a new direct target of miR-34 and demonstrate that this regulation interferes with several c-Kit-mediated effects on cancer cells.Therefore, this regulation may be potentially relevant for future diagnostic and therapeutic approaches.

View Article: PubMed Central - PubMed

Affiliation: Experimental and Molecular Pathology, Institute of Pathology, Ludwig-Maximilians-University München, D-80337 Munich, Germany.

ABSTRACT
The c-Kit receptor tyrosine kinase is commonly over-expressed in different types of cancer. p53 activation is known to result in the down-regulation of c-Kit. However, the underlying mechanism has remained unknown. Here, we show that the p53-induced miR-34 microRNA family mediates repression of c-Kit by p53 via a conserved seed-matching sequence in the c-Kit 3'-UTR. Ectopic miR-34a resulted in a decrease in Erk signaling and transformation, which was dependent on the down-regulation of c-Kit expression. Furthermore, ectopic expression of c-Kit conferred resistance of colorectal cancer (CRC) cells to treatment with 5-fluorouracil (5-FU), whereas ectopic miR-34a sensitized the cells to 5-FU. After stimulation with c-Kit ligand/stem cell factor (SCF) Colo320 CRC cells displayed increased migration/invasion, whereas ectopic miR-34a inhibited SCF-induced migration/invasion. Activation of a conditional c-Kit allele induced several stemness markers in DLD-1 CRC cells. In primary CRC samples elevated c-Kit expression also showed a positive correlation with markers of stemness, such as Lgr5, CD44, OLFM4, BMI-1 and β-catenin. On the contrary, activation of a conditional miR-34a allele in DLD-1 cells diminished the expression of c-Kit and several stemness markers (CD44, Lgr5 and BMI-1) and suppressed sphere formation. MiR-34a also suppressed enhanced sphere-formation after exposure to SCF. Taken together, our data establish c-Kit as a new direct target of miR-34 and demonstrate that this regulation interferes with several c-Kit-mediated effects on cancer cells. Therefore, this regulation may be potentially relevant for future diagnostic and therapeutic approaches.

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Related in: MedlinePlus

The p53/miR-34/c-Kit axisThe model depicts multiple tumor suppressive effects of miR-34a directly targeting c-Kit which were identified in this study. In tumors, p53 mutation/inactivation or CpG methylation of miR-34a/b/c promoters may abrogate this pathway [33, 91, 92]. miR-34a/b/c have multiple other targets besides c-Kit [33, 93]. The model was adapted from [94].
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Figure 8: The p53/miR-34/c-Kit axisThe model depicts multiple tumor suppressive effects of miR-34a directly targeting c-Kit which were identified in this study. In tumors, p53 mutation/inactivation or CpG methylation of miR-34a/b/c promoters may abrogate this pathway [33, 91, 92]. miR-34a/b/c have multiple other targets besides c-Kit [33, 93]. The model was adapted from [94].

Mentions: In this study c-Kit was identified as a new target of the miR-34 family. Since c-Kit plays a role in numerous cancer-associated pathways, these results extend the tumor suppressive mechanisms of miR-34. A model summarizing our findings is shown in Figure 8. miR-34-mediated down-regulation of c-Kit resulted in diminished Erk-phosphorylation levels, which was associated with decreased colony formation in soft agar and therefore a decrease in cellular transformation. Moreover, low endogenous c-Kit protein levels or a decrease in c-Kit caused by ectopic miR-34 were associated with increased chemosensitivity. Furthermore, miR-34a inhibited migration and invasion and also SCF-mediated enhancement of these processes was blocked by miR-34a. Finally, activation of c-Kit induced several stemness markers in CRC cell lines and was associated with their expression in primary CRC tumors, whereas activation of miR-34a in CRC cell lines resulted in a down-regulation of c-Kit and c-Kit-induced markers, and suppressed sphere-formation of CRC cells, indicating that CRC stemness may be controlled by the miR-34/c-Kit axis.


Repression of c-Kit by p53 is mediated by miR-34 and is associated with reduced chemoresistance, migration and stemness.

Siemens H, Jackstadt R, Kaller M, Hermeking H - Oncotarget (2013)

The p53/miR-34/c-Kit axisThe model depicts multiple tumor suppressive effects of miR-34a directly targeting c-Kit which were identified in this study. In tumors, p53 mutation/inactivation or CpG methylation of miR-34a/b/c promoters may abrogate this pathway [33, 91, 92]. miR-34a/b/c have multiple other targets besides c-Kit [33, 93]. The model was adapted from [94].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3824539&req=5

Figure 8: The p53/miR-34/c-Kit axisThe model depicts multiple tumor suppressive effects of miR-34a directly targeting c-Kit which were identified in this study. In tumors, p53 mutation/inactivation or CpG methylation of miR-34a/b/c promoters may abrogate this pathway [33, 91, 92]. miR-34a/b/c have multiple other targets besides c-Kit [33, 93]. The model was adapted from [94].
Mentions: In this study c-Kit was identified as a new target of the miR-34 family. Since c-Kit plays a role in numerous cancer-associated pathways, these results extend the tumor suppressive mechanisms of miR-34. A model summarizing our findings is shown in Figure 8. miR-34-mediated down-regulation of c-Kit resulted in diminished Erk-phosphorylation levels, which was associated with decreased colony formation in soft agar and therefore a decrease in cellular transformation. Moreover, low endogenous c-Kit protein levels or a decrease in c-Kit caused by ectopic miR-34 were associated with increased chemosensitivity. Furthermore, miR-34a inhibited migration and invasion and also SCF-mediated enhancement of these processes was blocked by miR-34a. Finally, activation of c-Kit induced several stemness markers in CRC cell lines and was associated with their expression in primary CRC tumors, whereas activation of miR-34a in CRC cell lines resulted in a down-regulation of c-Kit and c-Kit-induced markers, and suppressed sphere-formation of CRC cells, indicating that CRC stemness may be controlled by the miR-34/c-Kit axis.

Bottom Line: The c-Kit receptor tyrosine kinase is commonly over-expressed in different types of cancer. p53 activation is known to result in the down-regulation of c-Kit.Taken together, our data establish c-Kit as a new direct target of miR-34 and demonstrate that this regulation interferes with several c-Kit-mediated effects on cancer cells.Therefore, this regulation may be potentially relevant for future diagnostic and therapeutic approaches.

View Article: PubMed Central - PubMed

Affiliation: Experimental and Molecular Pathology, Institute of Pathology, Ludwig-Maximilians-University München, D-80337 Munich, Germany.

ABSTRACT
The c-Kit receptor tyrosine kinase is commonly over-expressed in different types of cancer. p53 activation is known to result in the down-regulation of c-Kit. However, the underlying mechanism has remained unknown. Here, we show that the p53-induced miR-34 microRNA family mediates repression of c-Kit by p53 via a conserved seed-matching sequence in the c-Kit 3'-UTR. Ectopic miR-34a resulted in a decrease in Erk signaling and transformation, which was dependent on the down-regulation of c-Kit expression. Furthermore, ectopic expression of c-Kit conferred resistance of colorectal cancer (CRC) cells to treatment with 5-fluorouracil (5-FU), whereas ectopic miR-34a sensitized the cells to 5-FU. After stimulation with c-Kit ligand/stem cell factor (SCF) Colo320 CRC cells displayed increased migration/invasion, whereas ectopic miR-34a inhibited SCF-induced migration/invasion. Activation of a conditional c-Kit allele induced several stemness markers in DLD-1 CRC cells. In primary CRC samples elevated c-Kit expression also showed a positive correlation with markers of stemness, such as Lgr5, CD44, OLFM4, BMI-1 and β-catenin. On the contrary, activation of a conditional miR-34a allele in DLD-1 cells diminished the expression of c-Kit and several stemness markers (CD44, Lgr5 and BMI-1) and suppressed sphere formation. MiR-34a also suppressed enhanced sphere-formation after exposure to SCF. Taken together, our data establish c-Kit as a new direct target of miR-34 and demonstrate that this regulation interferes with several c-Kit-mediated effects on cancer cells. Therefore, this regulation may be potentially relevant for future diagnostic and therapeutic approaches.

Show MeSH
Related in: MedlinePlus