Expression of the transformed phenotype induced by diverse acting viral oncogenes mediates sensitivity to growth suppression induced by caffeic Acid phenethyl ester (cape)

Caffeic acid phenethyl ester (CAPE) displays enhanced growth suppressive and toxic effects toward cloned rat embryo fibroblast (CREF) cells transformed by adenovirus type 5 (Ad5) or the Ad5 E1A transforming gene versus untransformed CREF cells (Su et al, Mol Carcinogen 4: 231-242, 1991). The present study was conducted to determine if transformation of CREF cells with additional oncogenes rendered these cells sensitive to the antiproliferative effect of CAPE. Additionally, studies were conducted to determine if reversion of the transformed phenotype could modify CAPE sensitivity. CAPE displayed increased growth suppressive activity toward CREF cells transformed by a number of oncogenes, including Ha-ras, v-src, v-raf, human papillomavirus type 18 (HPV-18) and human papillomavirus type 51 (HPV-51). Employing Ha-ras-transformed CREF (Ha-ras) and Ha-ras-transformed CREF cells overexpressing the Krev-1 suppressor gene (Ha-ras/Krev-1), evidence for a direct relationship between expression of the transformed phenotype and CAPE sensitivity was demonstrated. Ha-ras/Krev-1 cells displaying a suppression of the transformed phenotype exhibited increased resistance to CAPE-induced growth suppression versus Ha-ras cells, whereas Ha-ras/Krev-1 cells escaping transformation-suppression following in vivo growth in nude mice displayed enhanced sensitivity to growth-suppression induced by CAPE. Similarly, mutant Ad5 (H5hr1)-transformed and v-src-transformed CREF cells displaying a stable reversion in transformation also displayed a reduced sensitivity to CAPE versus their transformed counterparts. These observations indicate a direct relationship between expression of the transformed phenotype and CAPE sensitivity. Elucidation of the mechanism by which CAPE selectively inhibits growth of transformed cells should provide important insights into the critical molecular changes mediating expression of the transformed state and could help identify cellular targets for cancer therapy.

Transcriptional switching model for the regulation of tumorigenesis and metastasis by the ha-ras oncogene - transcriptional changes in the ha-ras tumor-suppressor gene lysyl oxidase

A model system is described that allows an analysis of the molecular and biochemical changes associated with expression and suppression of the oncogenic and metastatic phenotype of cloned rat embryo fibroblast (CREF) cells. Ha-ras-transformed CREF cells are morphologically transformed, anchorage-independent and both tumorigenic and metastatic in athymic nude mice and syngeneic Fischer rats. Co-expression of the Ha-ras oncogene and Krev-1 tumor suppressor gene in CREF cells results in suppression of in vitro transformation. In contrast, Ha-ras/Krev-1 transformed CREF cells retain, with greatly extended latency periods, both tumorigenic and metastatic capabilities in athymic nude mice. The present study investigates changes in the Ha-ms suppressor gene, rrg (lysyl oxidase), during expression and suppression of the oncogenic phenotype in CREF cells. Nontumorigenic CREF cells and CREF cells transformed by the Ha-ras and Krev-1 gene that express a suppression in in vitro transformation contain elevated levels of lysyl oxidase mRNA and protein. In contrast, Ha-ms and Ha-ras/Krev-1 nude mouse tumor- and nude mouse lung metastasis-derived CREF cells contain reduced levels of lysyl oxidase mRNA and protein. Nuclear run-on assays indicate that suppression of lysyl oxidase expression in transformed subclones of CREF cells correlates with a reduction in transcription of the lysyl oxidase gene. Taken together, the current studies support a transcriptional switching model in which lysyl oxidase expression correlates directly with suppression of the Ka-ms-induced transformation phenotype and escape from oncogenic suppression correlates with a transcriptional silencing of the lysyl oxidase gene and decreased lysyl oxidase mRNA and protein.

Caffeic acid phenethyl ester profoundly modifies protein synthesis profile in type 5 adenovirus-transformed cloned rat embryo fibroblast cells

Caffeic acid phenethyl ester (CAPE), an active component of propolis from bee hives, exerts a plethora of biological changes in diverse systems. These include antimitogenic, anticarcinogenic, anti-inflammatory and immunomodulatory responses. CAPE directly induces programmed cell death (apoptosis) in type 5 adenovirus (Ad5)-transformed cloned rat embryo fibroblast cells, wt3A. To identify the gene and protein expression changes induced by CAPE in wt3A cells we used a strategy involving in vitro translation of mRNAs followed by high resolution two-dimensional (2D) gel electrophoresis. This approach results in the detection of 745 spots, including 172 displaying differences in expression upon exposure to CAPE. A high proportion of spots show profound changes in spot intensity (42 spots with increased and 27 spots with decreased intensity) following CAPE treatment. These studies provide a basis for comparing these changes to known protein patterns of various cell populations with an ultimate aim of identifying families of polypeptides responsible for the up- and down-regulation of cellular proteins during CAPE-induced apoptosis. Specific newly appearing or completely disappearing spots (52 and 51 molecular species, respectively) will be used to attempt to identify and retrieve their cDNA counterparts from an ordered cDNA library. These approaches represent a novel strategy for cloning genes associated with and potentially mediating apoptosis.

Direct Response to Proton Beam Linear Energy Transfer (LET) in a Novel Polymer Gel Dosimeter Formulation

Linear energy transfer (LET) of clinical proton beams is an important parameter influencing the biological effects of radiation. This work demonstrates LET-induced response enhancement in novel formulations of polymer gel dosimeters, potentially useful for LET mapping of clinical proton beams. A series of four polymer gel dosimeters (labeled A through D), prepared based on the BANG3-Pro2 formulation, but with varying concentrations of polymerization modifiers, were irradiated by a clinical proton beam with a spread out Bragg peak modulation (SOBP) and read out using the OCTOPUS-IQ optical CT scanner. The evaluation of optical density profiles in the SOBP (constant physical dose) revealed response deviations at the distal end consistent with variations in gel composition. Maximum response deviations were as follows: −3% (under-response) for gel A, and over-response of 2%, 12%, and 17% for gels B, C, and D, respectively, relative to the mean dose in the center of the SOBP. This enhancement in optical response was correlated to LET by analytical calculations. Gels A and B showed no measurable dependence on LET. Gel C responded linearly in the limited range from 1.5 to 3.5 keV/μm. LET response of gel D was linear up to at least 5.5 keV/μm, with the threshold at about 1.3 keV/μm. These results suggest that it may be possible to develop a polymer gel system with direct optical response to LET for mapping of LET distributions for particle therapy beams.

Increased T-cell stimulating activity by mutated SEC2 correlates with its improved antitumour potency

AIMS

To investigate the improved antitumour activity of SAM-3 compared with recombinant staphylococcal enterotoxins C2 (rSEC2).

METHODS AND RESULTS

Methylthiazol tetrazolium and flow cytometry assays showed that the antitumour activity of SAM-3 in vivo was improved because of enhanced T-cell stimulating potency, resulting in massive activation of T cells, particularly CD4(+) and CD8(+) T cells, and subsequent cytokine release. Quantitative real-time PCR assay showed that despite similar Vβ specificities induced by rSEC2 and SAM-3, the quantities of activated T cells bearing specific Vβin vitro were different.

CONCLUSIONS

The results strongly suggested that the increased SAM-3-T-cell receptor (TCR) binding affinity contributed to massive T-cell activation and cytokine release, substantially amplifying antitumour immune response in vivo.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provided evidence for the mechanism of SAM-3 antitumour activity improvement compared with rSEC2. Results indicated that SAM-3 could be used as a potent powerful candidate agent for tumour treatment in clinics.

Intranasal administration of TAT-haFGF(₁₄₋₁₅₄) attenuates disease progression in a mouse model of Alzheimer's disease

Human acidic fibroblast growth factor (haFGF), a neurotrophin-like growth factor in the brain, plays important roles in the development, differentiation and regeneration of brain neurons, which makes it potential to treat Alzheimer's disease (AD). In this study, haFGF(14-154) and TAT-haFGF(14-154) (haFGF(14-154) fused with the cell-penetrating peptide transactivator of transcription protein transduction domain (TAT-PTD)) were intranasally administrated for 5 weeks to investigate the effects on senescence-accelerated mouse prone-8 (SAMP8) mice (a mouse model of AD). Results showed that TAT-PTD could increase the concentration of haFGF in the brain significantly, and TAT-haFGF(14-154) was more effective than haFGF(14-154) in the same dosage (300 μg/kg). Importantly, TAT-haFGF(14-154) improved the learning and memory abilities of SAMP8 mice in the behavioral test, and promoted the function of cholinergic system by measuring the relevant biomarkers (acetylcholine (ACh) level, acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) activities). TAT-haFGF(14-154) also significantly reduced β-amyloid protein(1-42) (Aβ(1-42)) deposits as well as the levels of Aβ soluble forms in the mice brains and prevented the neurons from apoptosis. Besides, the oxidative stress impairment in the brain and serum was also ameliorated. The results suggest that TAT-haFGF(14-154) could attenuate the disease progression of SAMP8 AD mice, and the mechanism is related to the regulation of neurons microenvironment including neurotransmitters, Aβ pathology and oxidative stress.

SU-E-T-225: A Comprehensive Evaluation of Real-Time Motion Tracking of a Surface Imaging System for Lung Treatment

PURPOSE

Applicability of the AlignRT surface imaging system was extensively investigated for real-time motion tracking in radiation therapy of lung cancer.

METHODS

A 4D computer-controlled motion phantom was employed to simulate a human breathing motion. An anthropomorphic thoracic phantom (a coronal cross-sectional area: ∼1,200 cm² ) was monitored during the 4D motion tracking. A breathing cycle from a healthy subject (breathing frequency: 0.2 Hz; maximum amplitude: vertical 7 mm, longitudinal 6 mm, and lateral 1.2 mm) was monitored and fed into the phantom control system. The real time monitoring was investigated by modifying a region of detection (the whole, a half, and a quarter of the area) and combination of 3 cameras (patient left, middle, and right).

RESULTS

The real-time tracking errors (detected breathing motion - the input of the subject's breathing) of the phantom motion using one camera (lateral, longitudinal, vertical) were (0.02±0.14 mm, -0.23±0.48 mm, -0.10±0.48 mm) with ipsilateral halves of the area (frame rate: 1.52 Hz), (0.06±0.10 mm, -0.30±0.30 mm, -0.03-0.35 mm) with ipsilateral quarters (frame rate: 1.95 Hz), and (0.19±0.96 mm, 0.29±1.50 mm, -0.46±1.58 mm) with contralateral quarters (frame rate: 3.04 Hz). The detection errors using 2-camera combinations (left-middle and right-middle) were (-0.06±0.06 mm, -0.43±0.21 mm, 0.00±0.22 mm) for the ipsilateral quarters and (-0.62±0.18 mm, -1.20±0.37 mm, 0.03±0.30 mm) for the contralateral quarters, respectively. The 3-camera tracking using halves of the area presented an error of (-0.04±0.12 mm, -0.69±0.35 mm, -0.08±0.38 mm) with a frame rate of 0.62 Hz.

CONCLUSIONS

To guarantee a sub-millimeter accuracy of realtime motion tracking in the lung treatment, combination of 2 cameras or less, a frame rate of greater than the Nyquist frequency (in this study fN = 2B (breathing frequency) = 0.4 Hz), and a tracking area of less than an ipsilateral half of thoracic area is highly recommended.

SU-E-J-214: Target Intrafraction Motion Dosimetric Impact on 5-Fraction Proton Prostate SBRT

PURPOSE

To investigate dosimetric impact of prostate intra-fraction motion to five fraction hypofractionated proton treatment with uniform scanning (US) and double scattering (DS) techniques using real-time prostate tracking data from electromagnetic transponder system.

METHODS

Prostate intra-fraction motion can have spatiotemporal interplay with proton treatment delivery. Five fraction (7.25Gy/fraction) prostate proton stereotactic body radiotherapy (SBRT) treatments were simulated for total 14 patients using in-house proton treatment simulation program. The US treatment was simulated by rigidly moving CTV through a series of temporal-spatial dose matrices indexed by energy layers, according to prostate motion traces. The CTV temporal doses of the whole treatment fraction were obtained and summed as final prostate CTV dose. The DS treatment was simulated by moving CTV through the energy layer summed dose matrix. For all patients, the fraction doses and the total dose to the CTV were presented for both DS and US treatments.

RESULTS

The CTV dose of different fractions indicated that its dose degradation depends on magnitude and direction of prostate intra-fraction motion and is patient specific. For one of the prostate motion traces investigated, only 70% of CTV received 100% prescribed dose for a simulated US treatment and 79% CTV had 100% dose for a DS treatment. Furthermore, DVH and isodose graphs of both treatments revealed that intra-fraction motion caused significant CTV cold and hot spots in US treatment whereas only cause CTV underdose in DS treatment.

CONCLUSIONS

Intra-fraction prostate motion causes dose uncertainty to CTV. In the 5 fraction prostate SBRT, prostate intra-fraction motion causes significant target dose degradation. In US treatment, spatiotemporal interplay between energy layers delivery and prostate motion leads to hot and cold spots in CTV for some patients with severe prostate intra-fraction motion. Further investigation of intra-fraction motion management and its impact on CTV dose is necessary.