Limits...
FBXW7 modulates cellular stress response and metastatic potential through ​HSF1 post-translational modification.

Kourtis N, Moubarak RS, Aranda-Orgilles B, Lui K, Aydin IT, Trimarchi T, Darvishian F, Salvaggio C, Zhong J, Bhatt K, Chen EI, Celebi JT, Lazaris C, Tsirigos A, Osman I, Hernando E, Aifantis I - Nat. Cell Biol. (2015)

Bottom Line: ​Heat-shock factor 1 (​HSF1) orchestrates the heat-shock response in eukaryotes.Although this pathway has evolved to help cells adapt in the presence of challenging conditions, it is co-opted in cancer to support malignancy.Here we show that the ubiquitin ligase ​FBXW7α interacts with ​HSF1 through a conserved motif phosphorylated by ​GSK3β and ​ERK1. ​FBXW7α ubiquitylates ​HSF1 and loss of ​FBXW7α results in impaired degradation of nuclear ​HSF1 and defective heat-shock response attenuation. ​FBXW7α is either mutated or transcriptionally downregulated in melanoma and ​HSF1 nuclear stabilization correlates with increased metastatic potential and disease progression. ​FBXW7α deficiency and subsequent ​HSF1 accumulation activates an invasion-supportive transcriptional program and enhances the metastatic potential of human melanoma cells.

View Article: PubMed Central - PubMed

ABSTRACT
​Heat-shock factor 1 (​HSF1) orchestrates the heat-shock response in eukaryotes. Although this pathway has evolved to help cells adapt in the presence of challenging conditions, it is co-opted in cancer to support malignancy. However, the mechanisms that regulate ​HSF1 and thus cellular stress response are poorly understood. Here we show that the ubiquitin ligase ​FBXW7α interacts with ​HSF1 through a conserved motif phosphorylated by ​GSK3β and ​ERK1. ​FBXW7α ubiquitylates ​HSF1 and loss of ​FBXW7α results in impaired degradation of nuclear ​HSF1 and defective heat-shock response attenuation. ​FBXW7α is either mutated or transcriptionally downregulated in melanoma and ​HSF1 nuclear stabilization correlates with increased metastatic potential and disease progression. ​FBXW7α deficiency and subsequent ​HSF1 accumulation activates an invasion-supportive transcriptional program and enhances the metastatic potential of human melanoma cells. These findings identify a post-translational mechanism of regulation of the ​HSF1 transcriptional program both in the presence of exogenous stress and in cancer.

Show MeSH

Related in: MedlinePlus

Nuclear HSF1 accumulation upon FBXW7 depletion results in increased metastasis in vivoIn vivo metastasis assay with 451Lu cells transduced with control (shLUC) or FBXW7 shRNA injected subcutaneously in NOG/SCID mice. (a) FBXW7 knockdown does not affect tumor growth or (b) tumor mass (shLUC: n=8; shFBXW7: n=7; n corresponds to number of mice per condition; ns: non significant; unpaired t-test) Error bars indicate mean ± SD. (c) Macroscopic pictures of mouse lungs and H&E-stained sections of lung metastases at termination of the experiment. Black circles mark metastatic foci (scale bar, 100 μm). (d) Whisker plots show the number of metastases per lung. Mean ± SEM is depicted shLUC: n=8; shFBXW7: n=7; n corresponds to number of mice per condition).(****P<0.0001; unpaired t-test). (e) HSF1, Ki67 and H&E-stained sections of subcutaneous tumors resected at termination of the experiment show that FBXW7 knockdown induces HSF1 nuclear accumulation but not proliferation (scale bar, 100 μm). (f) HSF1 is necessary for the increased metastatic potential of melanoma cells upon FBXW7 depletion. 451Lu cells were transduced with control (shLUC) or FBXW7 shRNA. Melanoma cells that acquired increased metastatic potential were subsequently transduced with the indicated shRNA lentiviruses. Transwell invasion assay was performed 3 days after transduction (P<0.001 for shScr versus shHSF1; n= 10 fields per biological replicate; 4 biological replicates; unpaired t-test). Error bars indicate mean ± SD.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4401662&req=5

Figure 6: Nuclear HSF1 accumulation upon FBXW7 depletion results in increased metastasis in vivoIn vivo metastasis assay with 451Lu cells transduced with control (shLUC) or FBXW7 shRNA injected subcutaneously in NOG/SCID mice. (a) FBXW7 knockdown does not affect tumor growth or (b) tumor mass (shLUC: n=8; shFBXW7: n=7; n corresponds to number of mice per condition; ns: non significant; unpaired t-test) Error bars indicate mean ± SD. (c) Macroscopic pictures of mouse lungs and H&E-stained sections of lung metastases at termination of the experiment. Black circles mark metastatic foci (scale bar, 100 μm). (d) Whisker plots show the number of metastases per lung. Mean ± SEM is depicted shLUC: n=8; shFBXW7: n=7; n corresponds to number of mice per condition).(****P<0.0001; unpaired t-test). (e) HSF1, Ki67 and H&E-stained sections of subcutaneous tumors resected at termination of the experiment show that FBXW7 knockdown induces HSF1 nuclear accumulation but not proliferation (scale bar, 100 μm). (f) HSF1 is necessary for the increased metastatic potential of melanoma cells upon FBXW7 depletion. 451Lu cells were transduced with control (shLUC) or FBXW7 shRNA. Melanoma cells that acquired increased metastatic potential were subsequently transduced with the indicated shRNA lentiviruses. Transwell invasion assay was performed 3 days after transduction (P<0.001 for shScr versus shHSF1; n= 10 fields per biological replicate; 4 biological replicates; unpaired t-test). Error bars indicate mean ± SD.

Mentions: To investigate the effect of FBXW7 downregulation and subsequent nuclear HSF1 accumulation on metastatic capacity of melanoma in vivo, 451Lu cells transduced with shFBXW7 or shLUC were injected into immune-compromised recipient mice. Although FBXW7 knockdown did not affect primary tumor growth (Fig. 6a, b; Supplementary Fig. 6a), it led to dramatic increase in the formation of metastatic foci in the lungs (Fig. 6c, d). Primary tumors consisting of melanoma cells carrying shFBXW7 exhibited prominent nuclear HSF1 staining compared to their control counterparts. Ki-67 staining did not reveal any difference in proliferation rates between the two treatments (Fig. 6e). Also, FBXW7 downregulation did not affect differentiation of melanoma cells (Supplementary Fig. 6b).


FBXW7 modulates cellular stress response and metastatic potential through ​HSF1 post-translational modification.

Kourtis N, Moubarak RS, Aranda-Orgilles B, Lui K, Aydin IT, Trimarchi T, Darvishian F, Salvaggio C, Zhong J, Bhatt K, Chen EI, Celebi JT, Lazaris C, Tsirigos A, Osman I, Hernando E, Aifantis I - Nat. Cell Biol. (2015)

Nuclear HSF1 accumulation upon FBXW7 depletion results in increased metastasis in vivoIn vivo metastasis assay with 451Lu cells transduced with control (shLUC) or FBXW7 shRNA injected subcutaneously in NOG/SCID mice. (a) FBXW7 knockdown does not affect tumor growth or (b) tumor mass (shLUC: n=8; shFBXW7: n=7; n corresponds to number of mice per condition; ns: non significant; unpaired t-test) Error bars indicate mean ± SD. (c) Macroscopic pictures of mouse lungs and H&E-stained sections of lung metastases at termination of the experiment. Black circles mark metastatic foci (scale bar, 100 μm). (d) Whisker plots show the number of metastases per lung. Mean ± SEM is depicted shLUC: n=8; shFBXW7: n=7; n corresponds to number of mice per condition).(****P<0.0001; unpaired t-test). (e) HSF1, Ki67 and H&E-stained sections of subcutaneous tumors resected at termination of the experiment show that FBXW7 knockdown induces HSF1 nuclear accumulation but not proliferation (scale bar, 100 μm). (f) HSF1 is necessary for the increased metastatic potential of melanoma cells upon FBXW7 depletion. 451Lu cells were transduced with control (shLUC) or FBXW7 shRNA. Melanoma cells that acquired increased metastatic potential were subsequently transduced with the indicated shRNA lentiviruses. Transwell invasion assay was performed 3 days after transduction (P<0.001 for shScr versus shHSF1; n= 10 fields per biological replicate; 4 biological replicates; unpaired t-test). Error bars indicate mean ± SD.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4401662&req=5

Figure 6: Nuclear HSF1 accumulation upon FBXW7 depletion results in increased metastasis in vivoIn vivo metastasis assay with 451Lu cells transduced with control (shLUC) or FBXW7 shRNA injected subcutaneously in NOG/SCID mice. (a) FBXW7 knockdown does not affect tumor growth or (b) tumor mass (shLUC: n=8; shFBXW7: n=7; n corresponds to number of mice per condition; ns: non significant; unpaired t-test) Error bars indicate mean ± SD. (c) Macroscopic pictures of mouse lungs and H&E-stained sections of lung metastases at termination of the experiment. Black circles mark metastatic foci (scale bar, 100 μm). (d) Whisker plots show the number of metastases per lung. Mean ± SEM is depicted shLUC: n=8; shFBXW7: n=7; n corresponds to number of mice per condition).(****P<0.0001; unpaired t-test). (e) HSF1, Ki67 and H&E-stained sections of subcutaneous tumors resected at termination of the experiment show that FBXW7 knockdown induces HSF1 nuclear accumulation but not proliferation (scale bar, 100 μm). (f) HSF1 is necessary for the increased metastatic potential of melanoma cells upon FBXW7 depletion. 451Lu cells were transduced with control (shLUC) or FBXW7 shRNA. Melanoma cells that acquired increased metastatic potential were subsequently transduced with the indicated shRNA lentiviruses. Transwell invasion assay was performed 3 days after transduction (P<0.001 for shScr versus shHSF1; n= 10 fields per biological replicate; 4 biological replicates; unpaired t-test). Error bars indicate mean ± SD.
Mentions: To investigate the effect of FBXW7 downregulation and subsequent nuclear HSF1 accumulation on metastatic capacity of melanoma in vivo, 451Lu cells transduced with shFBXW7 or shLUC were injected into immune-compromised recipient mice. Although FBXW7 knockdown did not affect primary tumor growth (Fig. 6a, b; Supplementary Fig. 6a), it led to dramatic increase in the formation of metastatic foci in the lungs (Fig. 6c, d). Primary tumors consisting of melanoma cells carrying shFBXW7 exhibited prominent nuclear HSF1 staining compared to their control counterparts. Ki-67 staining did not reveal any difference in proliferation rates between the two treatments (Fig. 6e). Also, FBXW7 downregulation did not affect differentiation of melanoma cells (Supplementary Fig. 6b).

Bottom Line: ​Heat-shock factor 1 (​HSF1) orchestrates the heat-shock response in eukaryotes.Although this pathway has evolved to help cells adapt in the presence of challenging conditions, it is co-opted in cancer to support malignancy.Here we show that the ubiquitin ligase ​FBXW7α interacts with ​HSF1 through a conserved motif phosphorylated by ​GSK3β and ​ERK1. ​FBXW7α ubiquitylates ​HSF1 and loss of ​FBXW7α results in impaired degradation of nuclear ​HSF1 and defective heat-shock response attenuation. ​FBXW7α is either mutated or transcriptionally downregulated in melanoma and ​HSF1 nuclear stabilization correlates with increased metastatic potential and disease progression. ​FBXW7α deficiency and subsequent ​HSF1 accumulation activates an invasion-supportive transcriptional program and enhances the metastatic potential of human melanoma cells.

View Article: PubMed Central - PubMed

ABSTRACT
​Heat-shock factor 1 (​HSF1) orchestrates the heat-shock response in eukaryotes. Although this pathway has evolved to help cells adapt in the presence of challenging conditions, it is co-opted in cancer to support malignancy. However, the mechanisms that regulate ​HSF1 and thus cellular stress response are poorly understood. Here we show that the ubiquitin ligase ​FBXW7α interacts with ​HSF1 through a conserved motif phosphorylated by ​GSK3β and ​ERK1. ​FBXW7α ubiquitylates ​HSF1 and loss of ​FBXW7α results in impaired degradation of nuclear ​HSF1 and defective heat-shock response attenuation. ​FBXW7α is either mutated or transcriptionally downregulated in melanoma and ​HSF1 nuclear stabilization correlates with increased metastatic potential and disease progression. ​FBXW7α deficiency and subsequent ​HSF1 accumulation activates an invasion-supportive transcriptional program and enhances the metastatic potential of human melanoma cells. These findings identify a post-translational mechanism of regulation of the ​HSF1 transcriptional program both in the presence of exogenous stress and in cancer.

Show MeSH
Related in: MedlinePlus