Haiquan Qiao

Opposing effects of arsenic trioxide on hepatocellular carcinomas in mice

Arsenic trioxide (As2O3) is a potent antitumor agent used to treat acute promyelocytic leukemia (APL) and, more recently, solid tumors. However, the dose of As2O3 required to suppress human xenographs in mice is markedly higher than that used to treat APL in humans. Paradoxically, low doses of As2O3 stimulate angiogenesis, which might be expected to promote tumor growth. Clearly, appropriate dosages of As2O3 are required to treat human patients to avoid toxicity and undesirable side effects. In the present study, we investigated As2O3 with respect to its toxicity and effects on tumor growth, angiogenesis and cell apoptosis using H22 hepatocellular carcinoma (HCC) cells in a mouse model of HCC. As2O3 inhibited tumor growth and angiogenesis, and enhanced tumor cell apoptosis at doses greater than 1 mg/kg, but mice lost weight and failed to thrive at doses of 4 mg/kg and greater. In contrast, low doses (<1 mg/kg) of As2O3 promoted tumor growth, upregulated the expression of vascular endothelial growth factor and tumor angiogenesis, and had no effect on tumor cell apoptosis. In vitro studies demonstrated that As2O3 inhibited the proliferation of H22 tumor cells and bovine aortic endothelial cells, and induced their apoptosis in a dose‐ and time‐dependent fashion, suggesting that the mechanism of As2O3‐mediated inhibition of tumor growth is due to direct effects of the drug on both tumor cells and endothelia. In summary, different doses of As2O3 have opposing effects on tumor growth and angiogenesis. The results demonstrate that As2O3 has a narrow window of therapeutic opportunity with respect to dosage, and that low doses of the drug as used in metronomic therapy should be used with extreme caution. (Cancer Sci 2006; 97: 675–681)

Inhibition of Akt reverses the acquired resistance to sorafenib by switching protective autophagy to autophagic cell death in hepatocellular carcinoma

Sorafenib is the standard first-line systemic drug for advanced hepatocellular carcinoma (HCC), but the acquired resistance to sorafenib results in limited benefits. Activation of Akt is thought to be responsible for mediating the acquired resistance to sorafenib. The present study aims to examine the underlying mechanism and seek potential strategies to reverse this resistance. Two sorafenib-resistant HCC cell lines, which had been established from human HCC HepG2 and Huh7 cells, were refractory to sorafenib-induced growth inhibition and apoptosis in vitro and in vivo. Sustained exposure to sorafenib activated Akt via the feedback loop of mTOR but independent of protein phosphatase 2A in HCC cells. Autophagy participated in the resistance to sorafenib as inhibition of autophagy reduced the sensitivity of sorafenib-resistant HCC cells to sorafenib, whereas activation of autophagy by rapamycin had the opposite effect. However, rapamycin did not show a synergistic effect with sorafenib to inhibit cell proliferation, while it also activated Akt via a feedback mechanism in sorafenib-resistant HCC cells. Inhibition of Akt reversed the acquired resistance to sorafenib by switching autophagy from a cytoprotective role to a death-promoting mechanism in the sorafenib-resistant HCC cells. Akt inhibition by GDC0068 synergized with sorafenib to suppress the growth of sorafenib-resistant HCC tumors that possessed the sorafenib-resistant feature in vivo. The results have provided evidence for clinical investigation of GDC0068, a novel ATP-competitive pan-Akt inhibitor, as the second-line treatment after the failure of sorafenib-medicated molecular targeted therapy for advanced HCC. Mol Cancer Ther; 13(6); 1589–98. ©2014 AACR.

Hydrogen Sulfide Attenuates Carbon Tetrachloride- Induced Hepatotoxicity, Liver Cirrhosis and Portal Hypertension in Rats

Background Hydrogen sulfide (H2S) displays vasodilative, anti-oxidative, anti-inflammatory and cytoprotective activities. Impaired production of H2S contributes to the increased intrahepatic resistance in cirrhotic livers. The study aimed to investigate the roles of H2S in carbon tetrachloride (CCl4)-induced hepatotoxicity, cirrhosis and portal hypertension. Methods and Findings Sodium hydrosulfide (NaHS), a donor of H2S, and DL-propargylglycine (PAG), an irreversible inhibitor of cystathionine γ-lyase (CSE), were applied to the rats to investigate the effects of H2S on CCl4-induced acute hepatotoxicity, cirrhosis and portal hypertension by measuring serum levels of H2S, hepatic H2S producing activity and CSE expression, liver function, activity of cytochrome P450 (CYP) 2E1, oxidative and inflammatory parameters, liver fibrosis and portal pressure. CCl4 significantly reduced serum levels of H2S, hepatic H2S production and CSE expression. NaHS attenuated CCl4-induced acute hepatotoxicity by supplementing exogenous H2S, which displayed anti-oxidative activities and inhibited the CYP2E1 activity. NaHS protected liver function, attenuated liver fibrosis, inhibited inflammation, and reduced the portal pressure, evidenced by the alterations of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), hyaluronic acid (HA), albumin, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and soluble intercellular adhesion molecule (ICAM)-1, liver histology, hepatic hydroxyproline content and α-smooth muscle actin (SMA) expression. PAG showed opposing effects to NaHS on most of the above parameters. Conclusions Exogenous H2S attenuates CCl4-induced hepatotoxicity, liver cirrhosis and portal hypertension by its multiple functions including anti-oxidation, anti-inflammation, cytoprotection and anti-fibrosis, indicating that targeting H2S may present a promising approach, particularly for its prophylactic effects, against liver cirrhosis and portal hypertension.

STAT3 interacts with Skp2/p27/p21 pathway to regulate the motility and invasion of gastric cancer cells.

The interleukin-6 (IL-6)/Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) pathway mediates cell proliferation and migration. S-phase kinase-associated protein-2 (Skp2) catalyzes the ubiquitylation of p27 and p21. Here we investigated that the cross-talk of the two pathways regulates motility and invasion of gastric cancer SGC7901 and MGC803 cells. Both cell lines endogenously secret IL-6, and blockage of IL-6 or JAK2 inhibited the activation of JAK2 and STAT3. Depletion of STAT3 downregulated Skp2 expression, and thereby increased the expression of p27 and p21. The depletion of STAT3 inhibited the ability of cells to migrate and invade, and impaired the cellular cytoskeleton mainly microtubules; while the depletion of p27 partially restored the impaired ability to migrate, and reversed the impaired microfilaments, further inhibited the ability to invade, but had little effect on microtubules and cellular adhering ability of STAT3-depleted cells. STAT3 depletion inhibited the activity of RhoA and the interaction with stathmin, downregulated the expression of pFAK (phosphorylated focal adhesion kinase), acetylated-tubulin, RECK (reversion-inducing-cysteine-rich protein with kazal motifs) and Sp1, upregulated E-cadherin, and reduced the activities of MMP (matrix metalloproteinase)-2 and -9. The depletion of p27 increased RhoA (Ras homolog family member A) activity, upregulated RECK, and downregulated E-cadherin and Sp1 in STAT3-depleted cells. The results indicate that the interaction between STAT3 and Skp2/p27/p21 pathway plays an important role in mediating the motility, migration and invasion of gastric cancer cells, and inhibition of STAT3 may be a useful therapeutic approach for metastasis of gastric cancer, but caution needs to be taken for its effects on Skp2/p27/p21 pathway.

Antisense hypoxia‐inducible factor 1α gene therapy enhances the therapeutic efficacy of doxorubicin to combat hepatocellular carcinoma

Hepatocellular carcinoma (HCC), one of the most common cancers worldwide, is resistant to anticancer drugs. Hypoxia is a major cause of tumor resistance to chemotherapy, and hypoxia‐inducible factor (HIF)‐1 is a key transcription factor in hypoxic responses. We have previously demonstrated that gene transfer of an antisense HIF‐1α expression vector downregulates expression of HIF‐1α and vascular endothelial growth factor (VEGF), and synergizes with immunotherapy to eradicate lymphomas. The aim of the present study was to determine whether gene transfer of antisense HIF‐1α could enhance the therapeutic efficacy of doxorubicin to combat HCC. Both antisense HIF‐1α therapy and doxorubicin suppressed the growth of subcutaneous human HepG2 tumors established in BALB/c nude mice, tumor angiogenesis, and cell proliferation, and induced tumor cell apoptosis. The combination therapy with antisense HIF‐1α and doxorubicin was more effective in suppressing tumor growth, angiogenesis, and cell proliferation, and inducing cell apoptosis than the respective monotherapies. Gene transfer of antisense HIF‐1α downregulated the expression of both HIF‐1α and VEGF, whereas doxorubicin only downregulated VEGF expression. Antisense HIF‐1α and doxorubicin synergized to downregulate VEGF expression. Both antisense HIF‐1α and doxorubicin inhibited expression of proliferating cell nuclear antigen, and combined to exert even stronger inhibition of proliferating cell nuclear antigen expression. Antisense HIF‐1α therapy warrants investigation as a therapeutic strategy to enhance the efficacy of doxorubicin for treating HCC. (Cancer Sci 2008; 99: 2055–2061)

Arsenic trioxide synergizes with B7H3-mediated immunotherapy to eradicate hepatocellular carcinomas

Arsenic trioxide (As2O3), a valuable anticancer drug for the treatment of acute promyelocytic leukemia, may also have therapeutic potential for the treatment of solid tumors. However, its therapeutic efficacy against solid tumors is lacking even at high dosages. Other therapeutic strategies are required to enhance the efficacy of As2O3 against solid tumors such as hepatocellular carcinoma (HCC), which is refractory to chemotherapy. B7H3, a new member of the B7 family, has been shown to induce antitumor immunity. Intratumoral injection of B7H3 plasmids eradicates small EL‐4 lymphomas, but monotherapy is ineffective against large tumors. Here we investigated whether As2O3 would synergize with B7H3 immunotherapy to combat HCC. Large subcutaneous H22 HCCs (0.7–0.8 cm in diameter) established in BALB/c mice were rapidly and completely eradicated when intratumoral administration of As2O3 was preceded by in situ gene transfer of B7H3. In contrast, neither As2O3 nor B7H3 monotherapy was effective. The antitumor activity of As2O3 was attributed to increased tumor‐cell apoptosis, perhaps as a result of direct cytotoxicity as well as decreased tumor angiogenesis. Combination therapy generated potent systemic antitumor immunity mediated by CD8+ and NK cells that was effective in combating a systemic challenge of 1 × 107 parental H22 cells. It led to the simultaneous and complete regression of multiple distant tumor nodules, concomitant with increased levels of serum IFN‐γ and cytotoxic T lymphocyte (CTL) activity. In conclusion, combining B7H3‐mediated immunotherapy with As2O3 warrants investigation as a therapeutic strategy to combat HCC, and other malignancies.

Downregulating hypoxia‐inducible factor‐2α improves the efficacy of doxorubicin in the treatment of hepatocellular carcinoma

The hypoxic microenvironment inside solid tumors, including hepatocellular carcinoma (HCC), is a major cause of tumor resistance to chemotherapy. The recently identified hypoxia‐inducible factor (HIF)‐2 executes the hypoxia response. Its expression feature and transcriptional targets indicate a possible dominance of HIF‐2 in regulating genes in HCC. The aim of the present study was to determine whether transfection of siRNA targeting HIF‐2α could enhance the efficacy of doxorubicin, the most commonly used drug in the treatment of HCC. Transfection of HIF‐2 siRNA into human HCC cells downregulated the expression of HIF‐2α, vascular endothelial growth factor (VEGF), transforming growth factor (TGF)‐α, and cyclin D1, but had little effect on the expression of HIF‐1α, fms‐related tyrosine kinase‐1 (Flt‐1), the glucose transporter (GLUT)‐1, and lactate dehydrogenase A (LDHA). Doxorubicin itself only downregulated VEGF expression. Furthermore, HIF‐2 siRNA inhibited proliferation, induced cell cycle arrest at the G0/G1 phase, and acted synergistically with doxorubicin to inhibit the growth of human HCC cells in vitro. Transfection of HIF‐2 siRNA also downregulated tumoral expression of HIF‐2α, VEGF, TGF‐α, and cyclin D1 in vivo, and acted synergistically with doxorubicin to suppress the growth of HepG2 tumors established in immunodeficient mice by inhibiting cell proliferation, tumor angiogenesis and microvessel perfusion. The results of the present study suggest that targeting HIF‐2α with siRNA warrants investigation as a potential strategy to enhance the efficacy of doxorubicin in the treatment of HCC. (Cancer Sci 2012; 103: 528–534)

The inhibitory role of b7-h4 in antitumor immunity: association with cancer progression and survival.

B7-H4 is one of the most recently identified members of B7 superfamily of costimulatory molecules serving as an inhibitory modulator of T-cell response. B7-H4 is broadly expressed in human peripheral tissues and inducibly expressed in immune cells. The expression of B7-H4 has been observed in various types of human cancer tissues, and its soluble form has been detected in blood samples from cancer patients. However, its precise physiological role is still elusive, as its receptor has not been identified and the expression levels are not consistent. This paper summarizes the pertinent data on the inhibitory role of B7-H4 in antitumor immunity and its association with cancer progression and survival in human patients. The paper also discusses the clinical significance of investigating B7-H4 as potential markers for cancer diagnosis and prognosis, and as therapeutic targets.

Upregulation of HIF-2α induced by sorafenib contributes to the resistance by activating the TGF-α/EGFR pathway in hepatocellular carcinoma cells.

Sorafenib, the first-line systemic drug for advanced hepatocellular carcinoma (HCC), has demonstrated limited benefits with very low response rates. Thus it is essential to investigate the underlying mechanisms for the resistance to sorafenib and seek potential strategy to enhance its efficacy. Hypoxic cells inside solid tumors are extremely resistant to therapies as their survival ability is increased due to the cellular adaptive response to hypoxia, which is controlled by hypoxia-inducible factor (HIF)-1 and HIF-2. Sorafenib inhibits HIF-1α synthesis, making the hypoxic response switch from HIF-1α- to HIF-2α-dependent pathways and providing a mechanism for more aggressive growth of tumors. The present study has demonstrated that upregulation of HIF-2α induced by sorafenib contributes to the resistance of hypoxic HCC cells by activating the transforming growth factor (TGF)-α/epidermal growth factor receptor (EGFR) pathway. Blocking the TGF-α/EGFR pathway by gefitinib, a specific EGFR inhibitor, reduced the activation of STAT (signal transducer and activator of transcription) 3, AKT and ERK (extracellular signal-regulated kinase), and synergized with sorafenib to inhibit proliferation and induce apoptosis of hypoxic HCC cells. Transfection of HIF-2α siRNA into HCC cells downregulated the expression of VEGF (vascular endothelial growth factor), cyclin D1, HIF-2α and TGF-α, and inhibited the activation of EGFR. HIF-2α siRNA inhibited the proliferation and promoted the apoptosis of HCC cells in vitro, and synergized with sorafenib to suppress the growth of HCC tumors in vivo. The results indicate that targeting HIF-2α-mediated activation of the TGF-α/EGFR pathway warrants further investigation as a potential strategy to enhance the efficacy of sorafenib for treating HCC.

Therapeutic effects of matrine on primary and metastatic breast cancer

Matrine, one of the main components extracted from a traditional Chinese herb, Sophora flavescens Ait, has displayed anti-cancer activity in several types of cancer cells. This study aims to evaluate the therapeutic benefits of matrine on primary and metastatic breast cancer. Matrine inhibited the viability of and induced apoptosis in human MCF-7 and mouse 4T1 breast cancer cells in a dose-dependent manner in vitro as shown by MTT assay, flow cytometry and laser scanning confocal microscopy. Administration of matrine inhibited the growth of primary tumors and their metastases to lungs and livers, in a dose-dependent manner, in a highly metastatic model of 4T1 breast cancer established in syngeneic Balb/c mice. Tumors from matrine-treated mice had a smaller proliferation index, shown by immunostaining with an anti-Ki-67 antibody, a greater apoptosis index, shown by TUNEL-staining, and a less microvessel density, shown by immunostaining with an anti-CD31 A antibody, compared to the controls. Western blot analysis of tumoral homogenates indicated that matrine therapy reduced the ratio of Bcl-2/Bax, downregulated the expressions of VEGF and VEGFR-2, and increased the activation of caspase-3 and caspase-9. This study suggests matrine may be a potent agent, from a natural resource, for treating metastatic breast cancer because of its anti-apoptotic, anti-proliferative and anti-angiogenic activities.