Identification of thioredoxin-interacting protein 1 as a hypoxia-inducible factor 1alpha-induced gene in pancreatic cancer.

To investigate the expression of thioredoxin-interacting protein (TXNIP) during hypoxia and its dependency on hypoxia-inducible factor 1alpha (HIF-1alpha) in pancreatic cancer cell lines. MiaPaCa-2 pancreatic cancer cells were transiently transfected with siRNA to HIF-1alpha and TXNIP protein measured after growth in normoxia or hypoxia. In addition, HIF-1alpha dependency was assessed by transiently transfecting MiaPaCa-2 pancreatic cancer cells with HIF-1alpha with a mutated oxygen degradation domain resulting in stable HIF-1alpha expression in normoxic conditions. Panc-1 pancreatic cancer cells with low endogenous TXNIP expression were stably transfected with TXNIP, and cell survival and response to platinum cancer agents were tested. Quantitative immunohistochemistry was utilized to measure the expression of TXNIP and thioredoxin 1 in human pancreatic cancer tissues. Thioredoxin-interacting protein was induced during hypoxia in pancreatic cancer cells in a HIF-1alpha-dependent manner. Overexpression of TXNIP in the Panc-1 cells resulted in a higher basal apoptosis and increased sensitivity to cisplatin and oxaliplatin. A negative correlation was observed between TXNIP and thioredoxin 1 expression in human pancreatic cancer tissues. Thioredoxin-interacting protein, a putative tumor suppressor gene, is induced in response to hypoxia in a HIF-1alpha-dependent manner in pancreatic cancer cells, resulting in increased apoptosis and increased sensitivity to platinum anticancer therapy. Increased TXNIP may be a mechanism to counterbalance the prosurvival effects of HIF-1alpha.

Baker AF ，Koh MY ，Williams RR ，James B ，Wang H ，Tate WR ，Gallegos A ，Von Hoff DD ，Han H ，Powis G ... -  《-》

Constitutive expression of hypoxia-inducible factor-1alpha renders pancreatic cancer cells resistant to apoptosis induced by hypoxia and nutrient deprivation.

Hypovasculature is an outstanding characteristic of pancreatic cancers in imaging diagnosis, suggesting that blood supply is poor in pancreatic cancer tissues. Despite poor blood supply, pancreatic cancer cells survive and proliferate in severe hypoxia and nutrient deprivation. To demonstrate how pancreatic cancer cells adapt themselves to hypoxia and nutrient deprivation, we investigated the expression of hypoxia-inducible factor 1alpha (HIF-1alpha) protein and HIF-1-inducible genes in human pancreatic cancer cell lines in comparison with other cancer cell lines. We found that HIF-1alpha protein was constitutively expressed in 15 of 20 pancreatic cancer cell lines (75%) but in none of other cancer cell lines tested in this study. The cells with constitutive expression of HIF-1alpha were more resistant to apoptosis induced by hypoxia and glucose deprivation than those without constitutive expression of HIF-1alpha. Transfection with HIF-1alpha transformed the latter cells resistant to apoptosis and increased in vivo tumorigenicity. Furthermore, anaerobic metabolism-associated genes, Glut1 and aldolase A, were more highly expressed in the cells with constitutive expression of HIF-1alpha than in the cells without it. These results suggest that constitutive expression of HIF-1alpha contributes to the survival and proliferation of pancreatic cancer cells in hypoxia and glucose deprivation through the activation of anaerobic metabolism.

Akakura N ，Kobayashi M ，Horiuchi I ，Suzuki A ，Wang J ，Chen J ，Niizeki H ，Kawamura Ki ，Hosokawa M ，Asaka M ... -  《CANCER RESEARCH》

[Impact of RNA interference targeting hypoxia-inducible factor-1alpha on chemosensitivity in esophageal squamous cell carcinoma cells under hypoxia].

To investigate the impact of RNA interference (RNAi) targeting hypoxia-inducible factor 1alpha (HIF-1 alpha) on chemosensitivity of esophageal squamous cell carcinoma cells under hypoxia. Human esophageal squamous cell carcinoma cells of the line EC9706 were cultured and divided into 3 groups: untransfected group, added with cobalt chloride (CoCl(2)), a chemical hypoxia inducer, for 8 h so as to establish a hypoxia model; control siRNA transfected group, transfected with control siRNA, and 30 h after the transfection exposed to CoCl(2) for 8 h; and HIF-1 alpha siRNA-transfected group, transfected with HIF-1 alpha siRNA, and 30 h later exposed to CoCl(2) for 8 h. Western blotting was used to detect the protein expression of HIF-1 alpha. Another EC9706 were cultured and divided into 3 groups to be treated as mentioned above, and then exposed to cisplantin or platixal under normoxic or hypoxic condition. 24 hours later 3-(4, 5-carboxymethoxypheny1)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) colorimetric assay was used to detect the inhibition rates of the cells. Further another EC9706 cells were cultured and then divided into 5 groups: cultured under normoxic condition, cultured under hypoxic condition for 8 h, transfected with control siRNA for 30 h and then under hypoxic condition for 8 h, transfected with HIF-1 alpha siRNA for 30 h and then under hypoxic condition for 8 h. The cell cycle was measured by flow cytometry. The HIF-1alpha protein expression of the HIF-1alpha siRNA group was significantly lower than those of the untransfected and control siRNA transfected groups. The inhibition rates of the EC9706 cells of the groups treated by cisplatin of different concentrations under normoxic condition were all significantly higher than the corresponding levels under hypoxic condition (all P < 0.01). The inhibition rates of the EC9706 cells of the groups treated by platixal of different concentrations under normoxic condition were all significantly higher than the corresponding levels under hypoxic condition (all P < 0.05) Under hypoxic condition, the inhibition rates of the HIF-1alpha siRNA transfected EC9706 cells treated by cisplatin and platixal of different concentrations were all significantly higher than those of the control siRNA transfected and untransfected EC9706 cells (all P < 0.05). Flow cytometry showed that under hypoxic condition the proportion of cells in G(1)-phase of the EC9706 cells was significantly higher, and the proportion of S-phase cells was significantly lower than those of the normoxic group (both P < 0.05), and under the same hypoxic condition the proportion of the EC9706 cells in G(1)-phase was significantly lower, and the proportion the EC9706 cells in S-phase was significantly higher than those of the normoxic group (all P < 0.05). The cell cycle arrest induced by HIF-1alpha may be the mechanism of the resistance to anticancer drugs of the esophageal squamous cell carcinoma cells under hypoxic condition. Blocking HIF-1alpha in esophageal squamous cell carcinoma cells may reverse the multidrug resistance of the tumor cells, so it may offer an avenue for gene therapy.

Wu XA ，Sun Y ，Fan QX ，Wang LX ，Wang RL ，Zhang L ... -  《-》

Hypoxic regulation of PFKFB-3 and PFKFB-4 gene expression in gastric and pancreatic cancer cell lines and expression of PFKFB genes in gastric cancers.

Previously we have shown that hypoxia strongly induces the expression of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3 and -4 (PFKFB-3 and PFKFB-4) genes in several cancer cell lines via a HIF-dependent mechanism. In this paper we studied the expression and hypoxic regulation of PFKFB-4 and PFKFB-3 mRNA as well as its correlation with HIF-1alpha, HIF-2alpha, VEGF and Glut1 mRNA expression in the pancreatic cancer cell line Panc1 and two gastric cancer cell lines MKN45 and NUGC3. This study clearly demonstrated that PFKFB-3 and PFKFB-4 mRNA are expresses in MKN45, NUGC3 and Panc1 cancers cells and that both genes are responsive to hypoxia in vitro. However, their basal level of expression and hypoxia responsiveness vary in the different cells studied. Particularly, PFKFB-3 mRNA is highly expressed in MKN45 and NUGC3 cancer cells, with the highest response to hypoxia in the NUGC3 cell line. The PFKFB-4 mRNA has a variable low basal level of expression in both gastric and pancreatic cancer cell lines. However, the highest hypoxia response of PFKFB-4 mRNA is found in the pancreatic cancer cell line Panc1. The basal level of PFKFB-4 protein expression is the highest in NUGC3 gastric cancer cell line and lowest in Panc1 cells, with the highest response to hypoxia in the pancreatic cancer cell line. Further studies showed that PFKFB-3 and PFKFB-4 gene expression was highly responsive to the hypoxia mimic dimethyloxalylglycine, a specific inhibitor of HIF-alpha hydroxylase enzymes, suggesting that the hypoxia responsiveness of PFKFB-3 and PFKFB-4 genes in these cell lines is regulated by the HIF transcription complex. The expression of VEGF and Glut1, which are known HIF-dependent genes, is also strongly induced under hypoxic conditions in gastric and pancreatic cancer cell lines. The levels of HIF-1alpha protein are increased in both gastric and pancreatic cancer cell lines under hypoxic conditions. However, the basal level of HIF-1alpha as well as HIF-2alpha mRNA expression and their hypoxia responsiveness are different in the MKN45 and NUGC3 cancer cells. Thus, the expression of HIF-1alpha mRNA is decreased in both gastric cancer cell lines treated by hypoxia or dimethyloxalylglycine, but HIF-2alpha mRNA expression is not changed significantly in NUGC3 and slightly increased in MKN45 cells. Expression of PFKFB-4 and PFKFB-3 was also studied in gastric cancers and corresponding nonmalignant tissue counterparts from the same patients on both the mRNA and protein levels. The expression of PFKFB-3 and PFKFB-4 mRNA as well as PFKFB-1 and PFKFB-2 mRNA was observed in normal human gastric tissue and was increased in malignant gastric tumors. The basal level of PFKFB-4 protein expression in gastric cancers was much higher as compared to the PFKFB-3 isoenzyme. In conclusion, this study provides evidence that PFKFB-4 and PFKFB-3 genes are also expressed in gastric and pancreatic cancer cells, they strongly respond to hypoxia via a HIF-1alpha dependent mechanism and, together with the expression of PFKFB-1 and PFKFB-2 genes, possibly have a significant role in the Warburg effect which is found in malignant cells.

Bobarykina AY ，Minchenko DO ，Opentanova IL ，Moenner M ，Caro J ，Esumi H ，Minchenko OH ... -  《ACTA BIOCHIMICA POLONICA》

Effects of YC-1 on hypoxia-inducible factor 1-driven transcription activity, cell proliferative vitality, and apoptosis in hypoxic human pancreatic cancer cells.

To investigate the effects of 3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole (YC-1) on HIF-1-driven transcription activity, cell proliferative vitality, and apoptosis in hypoxic human pancreatic cancer cells. Human pancreatic cancer PC-3 cells were incubated under normoxic or hypoxic conditions. YC-1 was added to the media with different concentrations. The HIF-1alpha protein expression was detected by means of immunocytochemical staining and Western blotting. Semiquantitative reverse transcriptase polymerase chain reaction was used to determine the mRNA expression of HIF-1alpha, vascular endothelial growth factor (VEGF), and glucose phosphate isomerase (GPI). A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and flow cytometry were used to detect the cells' proliferative vitality and apoptosis. Hypoxic PC-3 cells expressed a higher level of HIF-alpha protein in nucleus compared with the normoxic controls. When the dose of YC-1 was at 100 micromol/L, the expression location of HIF-alpha shifted from nucleus to cytoplasm. Western blotting revealed that YC-1 reduced the level of HIF-1alpha protein expression, and the inhibitory effect was dose dependent. Moreover, YC-1 dose dependently inhibited mRNA expression levels of VEGF and GPI in hypoxic cells. YC-1 inhibited proliferative vitality and induced apoptosis of hypoxic PC-3 cells in a dose-dependent manner. YC-1 inhibits HIF-1alpha expression in hypoxic pancreatic cancer cells, which is accompanied by the translocation of HIF-1alpha from nucleus to cytoplasm, decreased mRNA expression of VEGF and GPI, reduced cell proliferative vitality, and increased apoptosis. These results suggest that HIF-1 is a potential therapeutic target for pancreatic cancer.

Zhao Q ，Du J ，Gu H ，Teng X ，Zhang Q ，Qin H ，Liu N ... -  《-》