Seock Ah Im

Presently, there is no effective treatment for glioblastoma, the most malignant and common brain tumor. Angiogenic factors are potentially optimal targets for therapeutic strategies because they are essential for tumor growth and progression. In this study, we sought a strategy for efficiently delivering an antisense cDNA molecule of the vascular endothelial growth factor (VEGF) to glioma cells. The recombinant adenoviral vector Ad5CMV-alphaVEGF carried the coding sequence of wild-type VEGF165 cDNA in an antisense orientation. Infection of U-87 MG malignant glioma cells with the Ad5CMV-alphaVEGF resulted in reduction of the level of the endogenous VEGF mRNA and drastically decreased the production of the targeted secretory form of the VEGF protein. Treatment of s.c. human glioma tumors established in nude mice with intralesional injection of Ad5CMV-alphaVEGF inhibited tumor growth. Taken together, these findings indicate that the efficient down-regulation of the VEGF produced by tumoral cells using antisense strategies has an antitumor effect in vivo. This is the first time that an adenoviral vector is used to transfer antisense VEGF sequence into glioma cells in an animal model, and our results suggest that this system may have clinical and therapeutic utility.

Poly (ADP-ribose) polymerase (PARP) 1 is an essential molecule in DNA damage response by sensing DNA damage and docking DNA repair proteins on the damaged DNA site through a type of posttranslational modification, poly (ADP-Ribosyl)ation (PARylation). PARP inhibitors, which inhibit PARylation through competitively binding to NAD+ binding site of PARP1 and PARP2, have improved clinical benefits for BRCA mutated tumors, leading to their accelerated clinical application. However, the antitumor activities of PARP inhibitors in clinical development are different, due to PARP trapping activity beyond blocking PARylation reactions. In this review, we comprehensively address the current state of knowledge regarding the mechanisms of action of PARP inhibitors. We will also discuss the different effects of PARP inhibitors in combination with cytotoxic chemotherapeutic agents regarding the mechanism of regulating PARylation.

Tumor growth is partially dependent on angiogenesis, a process that relies on angiogenic factors. Tumorigenicity of cancer cells is thought to be associated with the production of various angiogenic factors that stimulate or inhibit the rate of endothelial cell migration and proliferation. However, the relative importance of specific individual factors originally studied in cancer cell lines has yet to be determined in vivo. In this study, we examined seven human glioma cell lines for dynamic changes of two major angiogenic factors, basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF), and for doubling time and tumorigenicity in nude mice. Various correlation studies demonstrated that in these glioma cell lines, VEGF expression correlated well with RBC density in tumor sections (r2 = 0.804) and with average tumor weight (r2 = 0.987). In contrast, bFGF expression in the observed glioma cell lines did not correlate with tumorigenicity (r2 = 0.001) or with VEGF expression (r2 = 0.255). Furthermore, there was no correlation between doubling time and tumorigenicity in these cell lines (r2 = 0.160). Taken together, these results suggest that VEGF plays a major role in glioma formation and that down-regulation of VEGF, rather than bFGF, would be a more effective choice for glioma gene therapy.

OBJECTIVE: The aim of this study was to evaluate efficacy and safety of the combination chemotherapy with irinotecan plus capecitabine in patients with advanced colorectal adenocarcinoma. METHODS: Patients with histologically proven advanced colorectal adenocarcinoma received a first-line chemotherapy with irinotecan 240 mg/m2 on day 1 and capecitabine 2,000 mg/m2/day as an intermittent regimen of 2 weeks of treatment followed by a 1-week rest. Treatment was repeated every 3 weeks. RESULTS: Thirty-nine patients were registered, and 36 were assessable for responses. Sixteen objective responses (44%) were observed with a median response duration of 6.9 months. Stable disease was documented in 14 cases (39%). The median time to progression was 6.7 months. The median overall survival was not reached at the time of analysis, and the 1-year survival rate was 67%. Two patients died: 1 due to sepsis not complicating myelosuppression, and 1 patient, known as a hepatitis B virus carrier prior to chemotherapy, died of hepatic failure, the cause of which was not clinically verified. Frequently encountered therapy-related events were leukopenia and gastrointestinal side effects including diarrhea. Severe hand-and-foot syndrome was observed in only 1 patient. CONCLUSIONS: The combination chemotherapy of irinotecan and capecitabine is an active and tolerable regimen for advanced colorectal adenocarcinoma, but the observed deaths suggest a future randomized trial that requires a cautious patient selection.