Regulation of HSP27 on NF-κB pathway activation may be involved in metastatic hepatocellular carcinoma cells apoptosis

Abstract

BackgroundDuring the process of metastasis, cells are subjected to various apoptotic stimuli. Aberrant expression of apoptotic regulators often contribute to cell metastasis. Heat shock protein 27(HSP27) is confirmed as an apoptosis regulator, but its antiapoptotic mechanism in metastatic hepatocellular carcinoma (HCC) cells remains unclear.MethodsLevels of HSP27 protein and its phosphorylation in Hep3B, MHCC97L to MHCC97H cells with different metastatic potentials were determined by western blot analysis. MHCC97H cells were transfected with specific small interference RNA (siRNA) against HSP27. The in vitro migration and invasion potentials of cells were evaluated by Transwell assay. The apoptosis ratio of MHCC97H cells was analyzed by TUNEL staining and Flow Cytometry. Alteration of signal transduction pathway after HSP27 knockdown in MHCC97H cells was evaluated through a Human Q Series Signal Transduction in Cancer Gene Array analysis. Nuclear NF-κB contentration and endogenous IKK activity were demonstrated by ELISA assay. The association of IKKα, IKKβ, IκBα with HSP27 and the association between IKKβ and IKKα in MHCC97H cells were determined by co-immunoprecipitation assay followed by western blot analysis.ResultsHSP27 protein and its phosphorylation increased in parallel with enhanced metastatic potentials of HCC cells. siRNA-mediated HSP27 knockdown in MHCC97H significantly suppressed cells migration and invasion in vitro and induced cell apoptosis; the prominently altered signal transduction pathway was NF-κB pathway after HSP27 knockdown in MHCC97H cells. Furthermore, inhibition of HSP27 expression led to a significant decrease of nuclear NF-κB contentration and endogenous IKK activity. In addition, HSP27 was associated with IKKα, IKKβ, IκBα in three HCC cells above. ELISA assay and western blot analysis also showed a decrease of the association between IKKβ and IKKα, the association between phosphor-HSP27 and IKK complex, and an increase of total IκBα but reducing tendency of phosphor-IκBα when HSP27 expression was efficiently knocked down in MHCC97H cells.ConclusionAltogether, these findings revealed a possible effect of HSP27 on apoptosis in metastatic HCC cells, in which HSP27 may regulate NF-kB pathway activation.

Clinical significance of HSP27 expression in colorectal cancer

“…HSP27 has been shown to inhibit apoptosis by increasing the antioxidant defense of cells (25). Moreover, HSP27 also inhibits apoptosis by regulating various upstream signaling pathways, such as those involving protein kinase akt (26), the Fas-mediated caspase-independent apoptotic pathway (27) and the nF-κB signaling pathway (28). These antiapoptotic effects underscore the potential role of HSP27 in cancer resistance to chemotherapy and radiotherapy, which has been extensively studied.…”

Comparison of the effect of p65 siRNA and curcumin in promoting apoptosis in esophageal squamous cell carcinoma cells and in nude mice

“…Subsequently, cells were treated with 50 µM curcumin in DMSO alone (final concentration of DMSO in media, 0.1%) or in combination with 5-FU and incubated for 72 h. These cells were harvested by rapid trypsinization, washed twice with PBS, and then the concentration of cells was adjusted to 1x10 5 . The certain number cells were stained with fluorescein isothiocyanate (FITC)-Annexin V-PI according to the protocol summarized in the Annexin V-FITC kit (Beckman Coulter).…”

“…NF-κB signaling pathway is mainly involved in cell growth, survival, differentiation and inhibition of apoptosis, thus making it a good target for cancer chemotherapy. Constitutive activation of NF-κB signaling pathway has been investigated in many human cancers, including hepatocellular, colonic, pancreatic and cervical cancers (5)(6)(7)(8). Therefore, blocking the activity of this pathway could be used for prevention and treatment of malignancy.…”

Proteome changes induced by overexpression of the p75 neurotrophin receptor (p75NTR) in breast cancer cells

“…Heat shock proteins such as HSP90, HSP70 and HSP27 are induced in response to a wide variety of physiological and environmental stress, including heat, reactive oxygen species or anticancer drugs, such as TRAIL, in order to protect cells from apoptosis (Zhuang et al, 2010). HSP27 can activate protective pathways such as NF-kB in hepatocellular carcinoma cells (Guo et al, 2009), and it is interesting to note that p75 NTR upregulates NF-kB in breast cancer (El Yazidi-Belkoura et al, 2003, Naderi et al, 2007. In our case, p75…”