HSF1 blockade-induced tumor thermotolerance abolishment is mediated by JNK-dependent caspase-3 activation.

We previously blocked the heat shock transcription factor 1 function with a dominant-negative mutant (mHSF1) in breast cancer cell line Bcap37, and found that mHSF1 sensitizes Bcap37 cells to hyperthermia by promoting the apoptotic process. Here we studied the mechanism of this abolishing process and how thermotolerance develops in Bcap37 cells. The results indicated that mHSF1 abolished acquired or intrinsic thermotolerance in Bcap37 cells by enhancing JNK and caspase-3 pathways, two stress-induced apoptotic pathways, after hyperthermia, and interference with either one of them attenuated hyperthermia-induced apoptosis. Furthermore, epistasis assay of these two pathways suggested that JNK was upstream of the caspase-3 pathway. Conversely, other hyperthermia-induced kinases implicated in cell survival and death, Akt, ERK or p38, did not influence the effect of mHSF1, indicating that these kinases were not implicated in this abolishing process. In addition, we found that the development of acquired thermotolerance of Bcap37 cells was associated with the suppression of JNK activation after mild preheat treatment and was not reduced by Akt, ERK or p38 inhibition. In contrast, the intrinsic thermotolerance of Bcap37 cells was due to the intrinsic high levels of Akt and ERK activities since Akt or ERK inhibition resulted in increased thermosensitivity of Bcap37 cells. Our results suggest that mHSF1 plays a valuable role in the thermotolerance abolishment of Bcap37 cells, which likely contributes to tumor therapy in combination with hyperthermia.

Current strategies and future directions of antiangiogenic tumor therapy.

Neovascularization is a prerequisite for progressive growth of most tumors and their metastases. Therefore, inhibition of angiogenesis could be one of the most promising strategies that might lead to the development of novel anticancer therapy. New blood vessels forming in tumors can be avoided by interfering the process of angiogenesis through suppressing the proangiogenic signal or augmenting the antiangiogenic factors. Concentrated efforts in this area have lead to the discovery of many proangiogenic factors as well as their inhibitors, and antiangiogenic factors. For the established tumor vasculature, tumor vasculature-targeted delivery of antiangiogenic substances and endothelial cell vaccines has been explored. Although some antiangiogenic drugs are currently in clinical development, for future reason, more efficient therapeutic methods, including antiangiogenic gene therapy strategy, targeted drug delivery system, and the combination of antiangiogenic agents with immunotherapy, chemotherapy or radiotherapy are being explored. With the development of tumor model assessment system, clinical use of the above antiangiogenic tumor therapy methods could be achieved.

An armed oncolytic adenovirus system, ZD55-gene, demonstrating potent antitumoral efficacy.

ONYX-015 is an attractive therapeutic adenovirus for cancer because it can selectively replicate in tumor cells and kill them. To date, clinical trials of this adenovirus have demonstrated marked safety but not potent enough when it was used alone. In this paper, we put forward a novel concept of Gene-ViroTherapy strategy and in this way, we constructed an armed therapeutic oncolytic adenovirus system, ZD55-gene, which is not only deleted of E1B 55-kD gene similar to ONYX-015, but also armed with foreign antitumor gene. ZD55-gene exhibited similar cytopathic effects and replication kinetics to that of ONYX-015 in vitro. Importantly, the carried gene is expressed and the expression level can increase with the replication of virus. Consequently, a significant antitumoral efficacy was observed when ZD55-CD/5-FU was used as an example in nude mice with subcutaneous human SW620 colon cancer. Our data demonstrated that ZD55-gene, which utilizing the Gene-ViroTherapy strategy, is more efficacious than each individual component in vivo.