Effects of FBXW7α on Expression and Localization of Heat Shock Transcription Factor 1 in Colorectal Cancer Cells

Objective To investigate the effect of FBXW7 on the expression and localization of HSF1 in colorectal cancer cells.

Methods The expression levels of HSF1 and pHSF1^Ser326 protein in FBXW7 deletion (KO) and wild-type (WT) FBXW7-expressing counterpart colorectal cancer cells were detected by Western blot. The nucleoprotein expression and localization of pHSF1^Ser326 in heat-shocked or recovery stage cells were observed by Western blot and immunofluorescence method.

Results The HSF1 expression level in DLD1 cells transfected with FBXW7α was decreased significantly (P < 0.01). The expression levels of HSF1 and pHSF1^Ser326 protein in FBXW7 KO cells were higher than those in WT cells (all P < 0.05). HSF1 and pHSF1^Ser326 in FBXW7 KO cells were mainly expressed in nucleus and weakly expressed in cytoplasm. After warm stimulation, the expression of HSF1 and pHSF1^Ser326 in WT cells recovered to the unstimulated level, while the expression of HSF1 and pHSF1^Ser326 in FBXW7 KO cells were higher in the nucleus (all P < 0.01).

Conclusion Loss of FBXW7 could affect the nuclear HSF1 recovery after warm stimulation. It may be associated with FBXW7 deletion inhibiting the degradation of nuclear HSF1.