Chien Yu Huang

GRP78 mediates the therapeutic efficacy of curcumin on colon cancer

Glucose-regulated protein 78 (GRP78) is the key regulator of endoplasmic reticular (ER) function. Expression of GRP78 was correlated with malignancy in different cancers. However, the role of GRP78 in the cytotoxic effect of curcumin on colon cancer cells is still unclear. A silencing RNA (siRNA) technique was used to knock down GRP78 expression. The anticancer effects of curcumin were assessed by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, a flow cytometric cell cycle analysis, and a terminal dexynucleotidyl transferase-mediated nick end labeling (TUNEL) assay. HT-29 cells expressed lower GRP78 compared with DLD-1 cells. The MTT assay revealed that HT-29 cells were more resistant to curcumin treatment than DLD-1 cells. GRP78KD cells showed more resistance to curcumin treatment compared with scrambled control cells. Overexpressed GRP78 in HT-29 cells increased the sensitivity to curcumin treatment. According to the cell cycle analysis and TUNEL assay, we found that apoptosis dramatically increased in scrambled control cells compared to GRP78KD DLD-1 cells after curcumin treatment. Finally, we evaluated levels of Bcl-2, BAX, and Bad and found that an increase of Bcl-2 level was observed in GRP78KD cells treated with curcumin. Those results were consistent with the increasing of resistance to curcumin after silencing of GRP78. The levels of GRP78 expression might determine the therapeutic efficacy of curcumin against colon cancer cells.

Proteomic Characterization of Annexin l (ANX1) and Heat Shock Protein 27 (HSP27) as Biomarkers for Invasive Hepatocellular Carcinoma Cells

To search for reliable biomarkers and drug targets for management of hepatocellular carcinoma (HCC), we performed a global proteomic analysis of a pair of HCC cell lines with distinct differentiation statuses using 2-DE coupled with MALDI-TOF MS. In total, 106 and 55 proteins were successfully identified from the total cell lysate and the cytosolic, nuclear and membrane fractions in well-differentiated (HepG2) and poorly differentiated (SK-Hep–1) HCC clonal variants, respectively. Among these proteins, nine spots corresponding to proteins differentially expressed between HCC cell types were selected and confirmed by immunofluorescence staining and western blotting. Notably, Annexin 1 (ANX1), ANX–2, vimentin and stress-associated proteins, such as GRP78, HSP75, HSC–70, protein disulfide isomerase (PDI), and heat shock protein–27 (HSP27), were exclusively up-regulated in SK-Hep–1 cells. Elevated levels of ANX–4 and antioxidant/metabolic enzymes, such as MnSOD, peroxiredoxin, NADP-dependent isocitrate dehydrogenase, α-enolase and UDP-glucose dehydrogenase, were observed in HepG2 cells. We functionally demonstrated that ANX1 and HSP27 were abundantly overexpressed only in highly invasive types of HCC cells, such as Mahlavu and SK-Hep–1. Knockdown of ANX1 or HSP27 in HCC cells resulted in a severe reduction in cell migration. The in-vitro observations of ANX1 and HSP27 expressions in HCC sample was demonstrated by immunohistochemical stains performed on HCC tissue microarrays. Poorly differentiated HCC tended to have stronger ANX1 and HSP27 expressions than well-differentiated or moderately differentiated HCC. Collectively, our findings suggest that ANX1 and HSP27 are two novel biomarkers for predicting invasive HCC phenotypes and could serve as potential treatment targets.

Glucose-regulated protein 78 (GRP78) regulates colon cancer metastasis through EMT biomarkers and the NRF-2/HO-1 pathway

Glucose-regulated protein 78 (GRP78) is a key chaperone and stress response protein. Previous studies have demonstrated that high GRP78 expression may be correlated with cancer progression and therapeutic response. However, the role of GRP78 in the metastasis of colon cancer is unclear. In this study, we used small interfering RNA (siRNA) to knock down GRP78 expression in colon cancer cells (HT-29 and DLD-1 cells). In wound-healing migration assays, we found that GRP78-knockdown (GRP78KD) cells showed better wound-healing ability than control cells. We also found that GRP78KD cells displayed a better migratory ability than control cells in migration and invasion assays. As we further dissected the underlying molecular mechanism, we found that silencing GRP78 may cause an increase in vimentin expression and a decrease in the E-cadherin level, which was correlated with the increase in migratory ability. In addition, we found that GRP78KD may activate the NRF-2/HO-1 pathway, and this activation was also correlated with the increase in cell invasiveness. Furthermore, we examined GRP78 expression in a tissue array and found that the GRP78 expression in metastatic adenocarcinoma in lymph nodes tended to be weaker than that in primary colonic adenocarcinoma. In conclusion, a low level of GRP78 may cause an increase in metastasis ability in colon cancer cells by altering E-cadherin and vimentin expression and activating the NRF-2/HO-1 signaling pathway. Our study demonstrates that low expression of GRP78 may correlate with a high risk of metastasis in colon cancer.

Alpha 7-nicotinic acetylcholine receptor mediates the sensitivity of gastric cancer cells to 5-fluorouracil

Gastric cancer is the second most common cause of cancer mortality worldwide. Most gastric cancer patients are asymptomatic until the advanced stages, for which current therapeutic treatments are suboptimal. 5-Fluorouracil (5-FU), an antimetabolite agent, is widely used in gastric cancer therapy. However, the presence of drug resistance in gastric cancer patients reduces the cytotoxic activity of 5-FU. In gastric cancer, no research has yet been conducted to analyze the effect of alpha 7-nicotinic acetylcholine receptor (A7-nAChR) on the therapeutic response to 5-FU. In this study, we generated A7-nAChR knockdown (A7-nAChR-KD) AGS cells by a small interfering RNA (siRNA) technique in gastric cancer cells. The anti-proliferative effects of 5-FU were determined by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, a terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay, and cell cycle determination. We found that A7-nAChR-KD cells were more resistant to 5-FU treatment compared with the scrambled control cells according to the MTT assay. The apoptotic cell population was increased more in scrambled control cells treated with 5-FU than A7-nAChR-KD cells according to the cell cycle distribution and TUNEL assays. We analyzed expression levels of survival and apoptosis-associated proteins (pAkt, Akt, Mcl-1, Bcl-2, Bad, and Bax) altered by 5-FU treatment. Survival and antiapoptosis signaling (pAkt, Akt, Mcl-1 and Bcl-2) was downregulated, and the proapoptotic proteins (Bad and Bax) were upregulated in 5-FU-treated control cells but expression levels of Bcl-2, Bad, and Bad were not altered in 5-FU-treated A7-nAChR-KD cells. This is consistent with A7-nAChR-KD cells exhibiting more resistance to 5-FU treatment. In our study, we carried out an in vitro study on AGS gastric cancer cell line to elucidate the anticancer efficacy and molecular mechanisms of A7-nAChR silencing on 5-FU-induced cell death. The results clearly showed that depletion of A7-nAChR suppressed the drug sensitivity of gastric cancer cells to 5-FU treatment.

The α7-nicotinic acetylcholine receptor mediates the sensitivity of gastric cancer cells to taxanes

Gastric cancer is difficult to cure because most patients are diagnosed at an advanced disease stage. Systemic chemotherapy remains an important therapy for gastric cancer, but both progression-free survival and disease-free survival associated with various combination regimens are limited because of refractoriness and chemoresistance. Accumulating evidence has revealed that the homomeric α7-nicotinic acetylcholine receptor (A7-nAChR) promotes human gastric cancer by driving cancer cell proliferation, migration, and metastasis. Therefore, A7-nAChR may serve as a potential therapeutic target for gastric cancer. However, the role of A7-nAChR in taxane therapy for gastric cancer was unclear. Cells were subjected to A7-nAChR knockdown (A7-nAChR KD) using short interfering RNA (siRNA). The anti-proliferative effects of taxane were assessed via 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT), terminal deoxynucleotidyl transferase–mediated nick-end labeling (TUNEL), and cell cycle distribution assays. A7-nAChR-KD cells exhibited low resistance to docetaxel and paclitaxel treatment, as measured by the MTT assay. Following paclitaxel treatment, the proportion of apoptotic cells was higher among A7-nAChR-KD cells than among scrambled control cells, as measured by cell cycle distribution and TUNEL assays. Further molecular analyses showed a reduction in the pAKT levels and a dramatic increase in the Bad levels in paclitaxel-treated A7-nAChR-KD cells but not in scrambled control cells. Following paclitaxel treatment, the level of Bax was slightly increased in both cell populations, whereas Poly (ADP-ribose) polymerase (PARP) cleavage was increased only in A7-nAChR-KD cells. These findings indicate that A7-nAChR-KD cells are more sensitive to paclitaxel treatment. We conclude that A7-nAChR may be a key biomarker for assessing the chemosensitivity of gastric cancer cells to taxane.

Glucose-regulated protein 94 mediates cancer progression via AKT and eNOS in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a crucial health issue worldwide. High glucose-regulated protein 94 (GRP94) expression has been observed in different types of cancer, suggesting a link between tumor progression and GRP94 expression. However, the mechanisms underlying the role of GRP94 in HCC progression remain unclear. We used specific small hairpin RNA (shRNA) to manipulate GRP94 expression in HCC cells. Tissue arrays, MTT assays, xCELLigence assays, and in vivo xenograft model were performed to identify clinicopathological correlations and to analyze cell growth. We found that high GRP94 expression reflected a poor response and a lower survival rate. In vitro and in vivo studies showed that silencing GRP94 suppressed cancer progression. Mechanistically, GRP94 knockdown reduced AKT, phospho-AKT, and eNOS levels but did not influence the AMPK pathway. Our results demonstrated that GRP94 is a key molecule in HCC progression that modulates the AKT pathway and eNOS levels. Our findings suggest that GRP94 may be a new prognostic and therapeutic target for HCC.

Glucose-regulated protein 78 mediates the therapeutic efficacy of 17-DMAG in colon cancer cells

Glucose-regulated protein 78 (GRP78) is expressed as part of the molecular response to endoplasmic reticulum (ER) stress and mediates protein folding within the cell. GRP78 is also an important biomarker of cancer progression and the therapeutic response of patients with different cancer types. However, the role of GRP78 in the cytotoxic effect of 17-DMAG in colon cancer cells remains unclear. GRP78 expression was knocked down by small interfering RNA (siRNA). The anticancer effects of 17-DMAG were assessed by an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, a flow cytometric cell-cycle analysis, and an Annexin V-propidium iodide (PI) apoptotic assay. We found that HT-29 cells expressed a lower level of GRP78 compared with DLD-1 cells. The MTT assay revealed that HT-29 cells were more sensitive to 17-DMAG treatment than DLD-1 cells. GRP78 knock down (GRP78KD) cells demonstrated an increased sensitivity to 17-DMAG treatment compared with the scrambled control cells. Based on the cell-cycle analysis and Annexin V-PI apoptotic assay, apoptosis dramatically increased in GRP78KD cells compared with scrambled control DLD-1 cells after these cells were treated with 17-DMAG. Finally, we observed a decrease in the level of Bcl-2 and an increase in the levels of Bad and Bax in GRP78KD cells treated with 17-DMAG. These results are consistent with an increased sensitivity to 17-DMAG after knock down of GRP78. The level of GRP78 expression may determine the therapeutic efficacy of 17-DMAG against colon cancer cells.

Glucose-regulated protein 78 mediates the anticancer efficacy of shikonin in hormone-refractory prostate cancer cells

Glucose-regulated protein 78 (GRP78) is a key modulator of prostate cancer progression and therapeutic resistance. Prostate cancer is a worldwide health problem, and therapeutic resistance is a critical obstacle for the treatment of hormone-refractory prostate cancer patients. Shikonin inhibits prostate cancer proliferation and metastasis. However, the role of GRP78 in the cytotoxic effect of shikonin in prostate cancer cells remains unclear. GRP78 expression was abolished using small interfering RNA (siRNA), and the anticancer effects of shikonin were assessed using MTT assays, the XCELLigence biosensor, flow cytometric cell cycle analysis, and Annexin V-PI apoptotic assays. PC-3 cells expressed more GRP78 than DU-145 cells, and the MTT assays revealed that DU-145 cells were more sensitive to shikonin than PC-3 cells. GRP78 knockdown (GRP78KD) PC-3 cells were more sensitive to shikonin treatment than scrambled siRNA control cells. Based on cell cycle analysis and AnnexinV-PI apoptotic assays, apoptosis dramatically increased in GRP78KD cells compared with the control PC-3 in response to shikonin. Finally, in response to shikonin treatment, Mcl-1 and Bcl-2 levels increased in the scrambled control cells treated with shikonin, whereas Bcl-2 decreased and Mcl-1 slightly increased in the GRP78KD PC-3 cells. The levels of Bax and Bad did not change in the scrambled control or GRP78KD cells after shikonin treatment. These results are consistent with the increased sensitivity to shikonin after knockdown of GRP78. GRP78 expression may determine the therapeutic efficacy of shikonin against prostate cancer cells.

IGFBP2 plays an important role in heat shock protein 27-mediated cancer progression and metastasis

Heat shock protein 27 (Hsp27) is a key chaperone that interacts with over 200 client proteins. The expression of Hsp27 might be correlated with poor outcome in many types of cancer. Previous study indicated that Hsp27 might be an important biomarker in hepatocellular carcinoma (HCC). However, the detailed mechanism is less well understood. The shRNA-mediated silencing of Hsp27 decreased the proliferation, migration and invasion of HCC cells. In a xenograft model, the silencing of Hsp27 reduced tumor progression. We revealed that the silencing of Hsp27 led to a reduction in insulin-like growth factor binding protein 2 (IGFBP2), which might mediate proliferation and metastasis through vimentin, snail and beta-catenin. The overexpression of IGFBP2 reversed the reductions in cell growth, migration and invasion. The tissue array results showed that HCC patients with high Hsp27 expression exhibited poor prognosis and increased metastasis. The Hsp27 expression was highly correlated with IGFPB2 in CRC specimen. ChIP and luciferase assays showed that Hsp27 does not directly bind the IGFBP2 promoter region to regulate the transcription of IGFBP2. In conclusion, our study demonstrated that Hsp27 is a key mediator of HCC progression and metastasis and that Hsp27 might regulate proliferation and metastasis through IGFBP2. This pathway might provide a new direction for the development of a novel therapeutic strategy for HCC.Heat shock protein 27 (Hsp27) is a key chaperone that interacts with over 200 client proteins. The expression of Hsp27 might be correlated with poor outcome in many types of cancer. Previous study indicated that Hsp27 might be an important biomarker in hepatocellular carcinoma (HCC). However, the detailed mechanism is less well understood. The shRNA-mediated silencing of Hsp27 decreased the proliferation, migration and invasion of HCC cells. In a xenograft model, the silencing of Hsp27 reduced tumor progression. We revealed that the silencing of Hsp27 led to a reduction in insulin-like growth factor binding protein 2 (IGFBP2), which might mediate proliferation and metastasis through vimentin, snail and beta-catenin. The overexpression of IGFBP2 reversed the reductions in cell growth, migration and invasion. The tissue array results showed that HCC patients with high Hsp27 expression exhibited poor prognosis and increased metastasis. The Hsp27 expression was highly correlated with IGFPB2 in CRC specimen. ChIP and luciferase assays showed that Hsp27 does not directly bind the IGFBP2 promoter region to regulate the transcription of IGFBP2. In conclusion, our study demonstrated that Hsp27 is a key mediator of HCC progression and metastasis and that Hsp27 might regulate proliferation and metastasis through IGFBP2. This pathway might provide a new direction for the development of a novel therapeutic strategy for HCC.

Glucose-regulated protein 94 mediates metastasis by CCT8 and the JNK pathway in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer death worldwide. Cancer metastasis is a major obstacle in clinical cancer therapy. The mechanisms underlying the metastasis of HCC remain unclear. Glucose-regulated protein 94 (GRP94) is a key protein involved in mediating cancer progression, and it is highly expressed in HCC specimens. However, the role of GRP94 in cancer metastasis is unclear. A specific short hairpin RNA (shRNA) was employed to knock down GRP94 gene expression in HCC cell lines. Wound-healing migration, transwell migration, and invasion assays were performed to determine the migration and invasive ability of HCC cells. We demonstrated that silencing GRP94 inhibited HCC cell wound healing, migration, and invasion. Furthermore, our findings indicated that GRP94 knockdown might attenuate HCC cell metastasis by inhibiting CCT8/c-Jun/EMT signaling. Our study indicated that silencing GRP94 significantly reduced the migration and invasion abilities of HCC cells. Moreover, depleting GRP94 inhibited cell migration and invasion by downregulating CCT8/c-Jun signaling. Thus, our data suggest that the GRP94/CCT8/c-Jun/EMT signaling cascade might be a new therapeutic target for HCC.