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Ralph Weichselbaum

Publications and source records attributed to Ralph Weichselbaum.

6 recordsLinked to original sources
PubMed2005

c-Abl tyrosine kinase regulates caspase-9 autocleavage in the apoptotic response to DNA damage.

Activation of the initiator caspase-9 is essential for induction of apoptosis by developmental signals, oncogenic transformation, and genotoxic stress. The c-Abl tyrosine kinase is also involved in the apoptotic response to DNA damage. The present results demonstrate that c-Abl binds directly to caspase-9. We show that c-Abl phosphorylates caspase-9 on Tyr-153 in vitro and in cells treated with DNA damaging agents. Moreover, inhibition of c-Abl with STI571 blocked DNA damage-induced autoprocessing of caspase-9 to the p35 subunit and activation of caspase-3. Caspase-9(Y153F) also attenuated DNA damage-induced processing of caspase-9 to p35, activation of caspase-3, and apoptosis. These findings indicate that caspase-9 autoprocessing is regulated by c-Abl in the apoptotic response to genotoxic stress.

Apoptosis↗
PubMed2004

TNFerade biologic, an adenovector with a radiation-inducible promoter, carrying the human tumor necrosis factor alpha gene: a phase I study in patients with solid tumors.

PURPOSE: TNFerade is a replication deficient adenovector that expresses human tumor necrosis factor alpha under control of the radiation-inducible Egr-1 promoter. The goals of this study were to determine the safety and toxicity of TNFerade in combination with radiation therapy. PATIENTS AND METHODS: TNFerade was administered by intratumoral administration, weekly for 6 weeks with concomitant radiation (30 to 70 Gy). Seven dose levels were studied (4 x 10(7) particle units [pu] to 4 x 10(11) pu) in patients with solid tumors being treated with radiation. RESULTS: Thirty-six patients were assessable for toxicity and 30 for tumor response. Most frequent TNFerade-related toxicities were fever (22%), injection site pain (19%), and chills (19%). No dose-limiting toxicities were observed. Overall, 21 of 30 patients (70%) demonstrated objective tumor response (five complete responses, nine partial responses, and seven minimal responses). In four of five patients with synchronous lesions, a differential response between lesions treated with TNFerade + radiation compared with radiation only was observed. CONCLUSION: This is the first human study with TNFerade and radiation. The integrated treatment was well tolerated in patients with predominantly prior treatment-refractory solid tumors. Controlled prospective clinical trials have been initiated to more fully define the therapeutic contribution of TNFerade.

Adenoviridae↗
PubMed2002

TNFerade Biologic: preclinical toxicology of a novel adenovector with a radiation-inducible promoter, carrying the human tumor necrosis factor alpha gene.

TNFerade Biologic (TNFerade) is a second-generation (E1-, E3-, and E4-deleted) replication-deficient adenovector carrying the transgene encoding for human tumor necrosis factor alpha (TNFalpha), regulated by the radiation-sensitive promoter Early Growth Response (Egr-1). We hypothesized that intratumoral injection of TNFerade followed by radiation would result in potentially therapeutic levels of TNFalpha with minimal toxicity. Three preclinical studies were conducted, the purpose of which was to characterize the toxicity and pharmacokinetics of TNFerade in conjunction with radiation in nude as well as immune-competent (Balb/c) mice. A total of 80 mice in the nude mouse toxicology study, all bearing human squamous cell carcinoma xenografts, 120 mice in the Balb/c study, and 33 nude mice in the pharmacokinetic study were used. Doses ranging from 4x10(9) to 4x10(10) particle units (pu) (4x10(11) pu in the Balb/c study) were explored, with and without radiation. In the nude mice studies, TNFerade was injected intratumorally, whereas in the Balb/c study, TNFerade was administered by subcutaneous injection. TNFerade was well tolerated. In the nude mice studies, no significant toxicity occurred in any dose group. In the Balb/c study, 6/40 mice at the top dose (4x10(11) pu) were sacrificed in moribund condition (5/20 in the TNFerade+radiation group, 1/20 in the TNFerade alone group). Necropsy showed local necrosis and ulceration at the site of the injection. No deaths or significant toxicity were observed at the lower dose levels (4x10(9) and 4x10(10) pu), indicating a large safety margin for initial studies in humans. The pharmacokinetic study demonstrated high sustained levels of TNFalpha in the tumor homogenate with no "spillover" to plasma, where TNFalpha levels were below the level of detection. Radiation increased intratumoral levels of TNFalpha by a factor of 12 (from 0.998 to 11.55 ng/g). In conclusion, a gene therapy approach with TNFerade, in combination with radiation, represents a potential way to utilize the potent anticancer activity of TNFalpha without systemic toxicity.

Adenoviridae↗
PubMedDate not supplied

Radiation therapy: activation for gene transcription and the development of genetic radiotherapy-therapeutic strategies in oncology.

Radiotherapy is a widely used local and regional modality for the treatment of cancer. Despite improved methods of radiation delivery, local recurrence accounts for treatment failure in most patients. Radiosensitizers have been studied as one approach for improving the effectiveness of radiotherapy. Few agents, however, have been shown to selectively increase the anti-tumor effects of radiation. Advances in our understanding of how cells respond molecularly to ionizing radiation have provided opportunities for the development of new approaches that selectively enhance radiotherapy of tumors. Cells respond to ionizing radiation with the activation of specific early and later response genes. These findings led us to the concept that promoters from these genes could be used to drive therapeutic transgenes introduced into irradiated tumor cells. In this strategy, designated genetic radiotherapy, radiation is combined with gene therapy, another local/regional modality, to spatially and temporally control transgene expression in the irradiated field. Tumor necrosis factor-alpha (TNF-alpha) was selected as the transgenic protein for its potent anti-tumor activity and synergistic interactions with ionizing radiation. The radio-inducible elements from the early growth response-1 (EGR-1) gene promoter have been inserted upstream to a cDNA encoding TNF-alpha and integrated into a replication-defective adenovirus (Ad.EGR-TNF). Preclinical studies have shown that tumors infected with Ad.EGR-TNF respond to radiation with induction of TNF-alpha expression and substantial increases in anti-tumor activity. Importantly, local production of TNF-alpha is not associated with the limiting toxicities encountered when this cytokine was administered systemically. Based on these findings, radiation in combination with intratumoral administration of a second generation Ad.EGR-TNF (TNFerade) has completed Phase I evaluation and has entered Phase II clinical trials.

Animals↗
PubMedDate not supplied

Lyn tyrosine kinase inhibits nuclear export of the p53 tumor suppressor.

The p53 tumor suppressor is activated in the cellular response to stress. Mdm2 inhibits p53-dependent transactivation and promotes degradation of p53 by the ubiquitin-proteosome pathway. The present studies demonstrate that p53 binds directly to the nuclear Lyn tyrosine kinase. Lyn increases p53 levels and stimulates p53-mediated transcription by a kinase-independent mechanism. The results also demonstrate that Lyn increases nuclear levels of ubiquitinated p53 by inhibiting export of p53 to the cytoplasm. In concert with these results, Lyn reverses Mdm2-mediated degradation of p53 and increases p53-dependent apoptosis. Our findings support a previously undefined role for nuclear Lyn in both activation and Mdm2-mediated regulation of p53.

Active Transport, Cell Nucleus↗