1: J Biol Chem. 2004 Jul 30;279(31):32651-9. Epub 2004 May 19. 

Expression of a dominant negative heat shock factor-1 construct inhibits
aneuploidy in prostate carcinoma cells.

Wang Y, Theriault JR, He H, Gong J, Calderwood SK.

Department of Adult Oncology, Dana-Farber Cancer Institute, Harvard Medical
School, Boston, Massachusetts 02115, USA.

Recent studies have implicated heat shock proteins (HSP) and heat shock
transcription factor 1 (HSF1) in tumor progression. We have examined the role of
HSF1 in the malignant phenotype of PC-3 prostate carcinoma cells. We have
developed a dominant negative construct of HSF1 that antagonizes transcription
from HSP promoters and results in the depletion of intracellular HSP 70. Our
studies indicate that expression of DN-HSF1 dramatically alters the DNA content
of PC-3 cells (derived from p53 null prostatic carcinoma) and inhibits
aneuploidy in these cells. This effect is due to prolonged expression of
DN-HSF1, and transient expression of the dominant negative factor from an
inducible promoter failed to cause the effect. Inhibition of aneuploidy in p53
null PC-3 cells by DN-HSF1 expression was recapitulated by expression within the
cells of wild type p53. Furthermore, cells expressing DN-HSF1 showed a profound
inhibition in the development of aneuploidy when exposed to chemical agents that
disrupt the mitotic spindle and prevent progression through metaphase.
Inhibition of aneuploidy in PC-3 cells expressing DN-HSF1 was associated with
delayed breakdown of cyclin B1 compared with controls, consistent with a role
for wild type HSF1 in the regulation of cyclin B1 degradation, a key step in the
control of mitosis. Our experiments therefore demonstrate that HSF1 plays a
functional role in cancer cells under nonstress conditions and influences cell
cycle behavior and progression through mitosis and promotes the development of
the aneuploid state.

PMID: 15152009 [PubMed - indexed for MEDLINE]


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2: J Biol Chem. 2003 May 2;278(18):15465-8. Epub 2003 Mar 12. 

p53 inhibitor pifithrin alpha can suppress heat shock and glucocorticoid
signaling pathways.

Komarova EA, Neznanov N, Komarov PG, Chernov MV, Wang K, Gudkov AV.

Department of Molecular Biology, Lerner Research Institute, Cleveland Clinic
Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.

Pifithrin alpha (PFTalpha) is a chemical compound isolated for its ability to
suppress p53-mediated transactivation. It can protect cells from p53-mediated
apoptosis induced by various stimuli and reduce sensitivity of mice to gamma
radiation. Identification of molecular targets of PFTalpha is likely to provide
new insights into mechanisms of regulation of p53 pathway and is important for
predicting potential risks associated with administration of PFTalpha-like p53
inhibitors in vivo. We found that PFTalpha, in addition to p53, can suppress
heat shock and glucocorticoid receptor signaling but has no effect on nuclear
factor-kappaB signaling. PFTalpha reduces activation of heat shock transcription
factor (HSF1) and increases cell sensitivity to heat. Moreover, it reduces
activation of glucocorticoid receptor and rescues mouse thymocytes in vitro and
in vivo from apoptotic death after dexamethasone treatment. PFTalpha affected
both signaling pathways in a p53-independent manner. These observations suggest
that PFTalpha targets some unknown factor that is common for three major signal
transduction pathways.

PMID: 12637507 [PubMed - indexed for MEDLINE]


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3: Int J Radiat Biol. 2002 Jan;78(1):17-27. 

Ukrain, an alkaloid thiophosphoric acid derivative of Chelidonium majus L.
protects human fibroblasts but not human tumour cells in vitro against ionizing
radiation.

Cordes N, Plasswilm L, Bamberg M, Rodemann HP.

Section of Radiobiology and Molecular Environmental Research,
Eberhard-Karls-University Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tubingen,
Germany.

PURPOSE: Ukrain, an alkaloid thiophosphoric acid derivative of Chelidonium majus
L., has demonstrated a promising impact on chemotherapy in a variety of
malignancies. The effects of the drug on cell survival, alteration of the cell
cycle and induction of apoptosis were examined without and in combination with
ionizing radiation (IR). The TP53 status of the cell lines used was also
investigated. MATERIALS AND METHODS: Exponentially growing human tumour cell
lines MDA-MB-231 (breast), PA-TU-8902 (pancreas), CCL-221 (colorectal), U-138MG
(glioblastoma), and human skin and lung fibroblastic cells, HSF1, HSF2 and
CCD32-LU were studied by colony assay, flow cytometry (cell-cycle, annexin-V
staining for apoptosis) and Western blotting. Ukrain was used in concentrations
from 0.1 to 50 microg ml(-1) for 1, 3 and 24 h and radiation as single doses of
1-10Gy. Combined drug-radiation exposure employed 1 microg ml(-1) Ukrain for 24h
plus 2-8 Gy. RESULTS: Ukrain cytotoxicity was time- and dose-dependent. The
combination of Ukrain plus IR gave enhanced toxicity in CCL-221 and U-138MG
cells, but not in MDA-MB-231 and PA-TU-8902 cells. Most strikingly, a
radioprotective effect was found in normal human skin and lung fibroblasts.
Flow-cytometry analyses supported the differential and cell line-specific
cytotoxicity of Ukrain. CCL-221 and U-138MG cells accumulated in G2 after 24-h
Ukrain treatment, whereas no alterations were detected in the other tumour cells
and normal fibroblasts tested. Western blotting of TP53 demonstrated
non-functional overexpression in all tumour cell lines without affecting p21.
HSF1 presented wild-type TP53 and a p21 response after IR. Flowcytometric
analyses of annexin-V staining showed no induction of apoptosis after Ukrain
treatment in comparison with untreated controls. CONCLUSIONS: Differential
effects of Ukrain in modulating radiation toxicity of human cancer cell lines
and its protective effect in normal human fibroblasts suggest that this alkaloid
may have potential properties for clinical radiochemotherapy.

PMID: 11747550 [PubMed - indexed for MEDLINE]


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