Sublethal hyperthermia enhances anticancer activity of doxorubicin in chronically hypoxic HepG2 cells through ROS-dependent mechanism.

Thermal ablation in combination with transarterial chemoembolization (TACE) has been reported to exert a more powerful antitumor effect than thermal ablation alone in hepatocellular carcinoma patients. However, the underlying mechanisms remain unclear. The purpose of the present study was to evaluate whether sublethal hyperthermia encountered in the periablation zone during thermal ablation enhances the anticancer activity of doxorubicin in chronically hypoxic (encountered in the tumor area after TACE) liver cancer cells and to explore the underlying mechanisms. In the present study, HepG2 cells precultured under chronic hypoxic conditions (1% oxygen) were treated in a 42°C water bath for 15 or 30 min, followed by incubation with doxorubicin. Assays were then performed to determine intracellular uptake of doxorubicin, cell viability, apoptosis, cell cycle, mitochondrial membrane potential (MMP), reactive oxygen species (ROS), and total antioxidant capacity. The results confirmed that sublethal hyperthermia enhanced the intracellular uptake of doxorubicin into hypoxic HepG2 cells. Hyperthermia combined with doxorubicin led to a greater inhibition of cell viability and increased apoptosis in hypoxic HepG2 cells as compared with hyperthermia or doxorubicin alone. In addition, the combination induced apoptosis by increasing ROS and causing disruption of MMP. Pretreatment with the ROS scavenger N-acetyl cysteine significantly inhibited the apoptotic response, suggesting that cell death is ROS-dependent. These findings suggested that sublethal hyperthermia enhances the anticancer activity of doxorubicin in hypoxic HepG2 cells via a ROS-dependent mechanism.

[Experimental studies of rAd-p53 injection by interventional approach for the treatment of rabbit VX2 liver cancer].

OBJECTIVES: To evaluate the efficacy of recombinant human adenovirus p53 gene therapy (rAd-p53) in the rabbit VX2 liver cancer model using different interventional therapy approach. METHODS: Thirty New Zealand rabbits implanted with VX2 tumor in the liver were randomized into five groups with six of each. The tumor volumes (V1) were measured by MRI and CT scan 11 days after tumors implanted. The interventional therapy scheme performed as below: intraarterial 0.9% saline solution perfusion in group A, transcatheter arterial embolization with 0.5 ml ultrafluid lipiodol in group B, intraarterial rAd-p53 gene perfusion in group C (1 x 10(6)/VP); intraarterial rAd-p53 gene perfusion (1 x 10(6)/VP) in combination with transcatheter arterial embolization (ultrofluid lipiodol, 0.5 ml) in group D and intratumoral rAd-p53 gene (1 x 10(6)/VP) injection in group E. The tumor volumes (V2) were measured by MRI and CT scan, and the tumor growth ratios were calculated 14 days after interventional procedures. Then all animals were sacrificed. RESULTS: The tumor tissues were explanted for immunohistochemistry to observe the expressions of vascular endothelial cell growth factor (VEGF) and factor VIII. Microvessel density (MVD) of the tumor tissues was assessed by factor VIII immunohistochemical analysis. In addition, apoptotic index was assessed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. The tumor volumes before therapy were (79.4+/-8.2), (75.3+/-7.8), (74.6+/-6.6), (78.7+/-9.1), (75.8+/-8.4) mm(3) respectively, without differences found among them (F = 12.248, P = 0.0636). But the tumor volumes after therapy were (564.7+/-96.7), (176.5+/-83.2), (239.6+/-42.8), (159.8+/-58.6), (334.7+/-32.6) mm(3) respectively (F = 24.537, P = 0.0218). The tumor growth ratios were 6.9, 2.6, 3.1, 1.6 and 4.1 respectively. The mean apoptosis index were 12.0%+/-1.1%, 14.5%+/-2.1%, 17.6%+/-2.3%, 18.6%+/-2.3% and 19.6%+/-2.5% respectively. with significant differences in group E in comparison with the other four groups. Mean positive ratio of VEGF was 50.0%, 83.3%, 83.3%, 50.0% and 50.0% respectively, with significant differences observed in group B and group C compared with the other three groups (F = 7.84, P = 0.019). The differences of VIII factor positive expression ratio among each group were significant (F = 0.854, P = 0.018). Statistical analysis showed a positive correlation between the expression of VEGF and MVD (r = 2.400, P = 0.0233). CONCLUSION: The rAd-p53 has effective treatment outcomes in VX2 rabbit liver cancer, and intra-arterial rAd-p53 gene perfusion in combination with transcatheter arterial embolization is the best approach in comparison with intra-arterial rAd-p53 gene perfusion, transcatheter arterial embolization and intratumoral rAd-p53 gene injection alone.

Embolic effects of Bletilla striata microspheres in renal artery and transplanted VX2 liver tumor model in rabbits.

OBJECTIVES: To evaluate the characteristics of Bletilla striata microspheres (BSMs) and its effects as an embolic agent in a rabbit model. METHODS: BSMs were prepared with an emulsification-cool condensation-chemical cross-linking method. The characteristics of BSMs in vitro were observed. Embolization experiments were performed in renal artery of rabbit and in a rabbit liver VX2 carcinoma model. Seventy-two New Zealand rabbits were divided into 2 groups, and the right renal artery was embolized with BSMs (200 µm in diameter) in the experimental group and with polyvinyl alcohol (PVA) of the same size in the control group. The pathological findings were examined with hematoxylin-eosin and Masson stainings. Liver and renal functions were tested before and after embolization. VX2 tumor was transplanted in 15 New Zealand rabbits, which were randomly divided into 3 groups (n=5). Group A were treated with saline, group B with a mixture of doxorubicin and lipiodol, and group C with hepatic arterial infusion of BSMs (200 µm in diameter). Tumor growth rate was evaluated by magnetic resonance imaging scan. Apoptosis-related factors (bax, bcl-2) and tumor vascular endothelial cell growth factor (VEGF) were evaluated through immunohistochemical staining. RESULTS: The characteristics of BSMs in vitro were in full compliance with the requirements for use in interventional procedures. In the renal artery embolization experiment, after BSMs intervention, it was more difficult to form collateral circulation than that with PVAs, and the kidney manifested atrophy and calcification. There were no significant difference of liver and renal functions in rabbits between groups. In the liver VX2 carcinoma embolization experiment, compared with group A, the growth rate of VX2 liver tumor and Bcl-2 levels was reduced, while apoptosis index, Bax, and VEGF were increased in group B (P<0.05). There were no significant difference between groups B and C (P>0.05). CONCLUSIONS: The characteristics of BSMs in vitro and in vivo meet the requirements for its use as an embolic agent in interventional approaches.

Radiofrequency ablation combined with transarterial chemoembolization for liver metastases from gastrointestinal cancers.

Transarterial chemoembolization (TACE) combined with radiofrequency ablation (RFA) has been reported to be effective for local control of different-sized hepatocellular carcinomas. However, it is unclear if these benefits could also be applicable to different-sized liver metastases from gastrointestinal cancers. The aim of this study was to evaluate the outcomes of TACE combined with RFA for liver metastases from gastrointestinal cancers. In this study, we retrospectively analyzed clinical data of 19 consecutive patients who had a total of 26 liver metastatic lesions from gastrointestinal cancers and underwent RFA followed by first-time TACE treatment. The tumor recurrence, overall survival rate and procedure-related complications were evaluated. Moreover, patients' demographics and tumor characteristics were analyzed to determine their impact on the outcomes. The technical success of TACE plus RFA was achieved with 2 major procedure-related complications found. The mean follow-up was 21.3 months. The total 1-, 2-, and 3-year survival rate was 89.4%, 52.6%, and 35.1%, respectively. It was found that the tumor size and the ratio of enhancement area were significant factors that influenced the overall survival. In conclusion, patients with gastrointestinal cancer-derived liver metastatic lesions of smaller size and larger enhancement area are considered appropriate candidates for TACE plus RFA.