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Biomedical subjects
L Rigby
Publications and source records attributed to L Rigby.
Alteration in p53 modulates glial proteins in human glial tumour cells.
In transformed human glial cells, abnormalities of the p53 gene and altered expression of glial-specific properties (GSPs) have been observed. We therefore investigated whether (i) expression of the altered p53 protein is involved in the reduced expression of GSPs; and (ii) expression of the wild-type p53 (wt-p53) gene leads to induction of GSPs. We first determined that the p53 gene is mutated in human glioblastoma U-373MG cells. In these cells, and in human T-98G glioblastoma cells reported to possess a mutated p53 (m-p53) gene, nuclear m-p53 expression was intense while GSP expression was low in the same cell as revealed by double labelling immunocytochemistry. Conversely, glial fibrillary acidic protein (GFAP) and glutamate synthase (GS) were expressed in cells devoid of nuclear m-p53 immnunoreactivity. Therefore, a mutually exclusive relationship exists between the cytoplasmic GSPs and nuclear m-p53. Upon treatment with retinoic acid (RA) and dibutyryl cyclic AMP (dbcAMP), overall GSP staining were increased concomitant with suppression of nuclear m-p53. Their mutually exclusive expression pattern was maintained suggesting a functional relationship. This is supported by the observation of a similar mutually exclusive expression pattern for p53 and GSPs in pathologic specimens of human glioblastoma tissues. We then explored the role of the wt-p53 gene in the induction of GSPs using a wt-p53 tetracycline-regulated conditional expression system in human LN-Z308 glioblastoma cells. These cells normally express no p53 and no appreciable levels of GS or GFAP. Induced expression of wt-p53 lead to induction of GSP. These observations are consistent with the hypotheses that (i) nuclear m-p53 expression and cytoplasmic expression of GFAP and GS are inversely correlated, and (ii) expression of the wt-p53 gene leads to the expression of GSPs.
Amino Acid Sequence↗
Mutant p53 may selectively suppress glial specific proteins in pluripotential human neuroectodermal tumor cells.
The p53 gene is mutated in pluripotential human neuroectodermal tumor DAOY cells which express both glial and neuronal markers. In most cells, nuclear m-p53 immunostaining was intense while cytoplasmic glial specific proteins (GSPs) were present at low levels. Conversely, glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS) were expressed in the few cells devoid of nuclear m-p53 immunoreactivity. The level of neuron specific enolase (NSE) staining was low and not different between p53 positive and p53 negative cells. Therefore, a selective, mutually exclusive expression relationship exists between cytoplasmic GSPs and nuclear m-p53. Upon treatment with epidermal growth factor (EGF) and dibutyrylcyclic AMP, overall cytoplasmic GFAP and GS levels were increased while nuclear p53 was suppressed but a mutually exclusive expression pattern between these proteins was maintained. In cells which also express NSE, GFAP was selectively stimulated suggesting that nuclear expression of m-p53 and cytoplasmic expression of GSPs may be functionally related.
Cytoplasm↗
Conformal radiotherapy of the pelvis: assessment of acute toxicity.
During the last 3 years the Royal Marsden Hospital (RMH) has conducted a prospective randomised trial of conformal pelvic radiotherapy in which dose/volume data and acute toxicity scores have been determined prospectively. Pending completion of the trial, a preliminary analysis has been undertaken of the volume reductions achieved, and of some of the symptom scores. The average symptom score increased during radiotherapy, more markedly for bowel than bladder symptoms. In comparing total doses of 30-38 Gy with 56-65 Gy, watery bowel motions were more frequent with the higher doses (p = 0.013) but in the high-dose group neither this symptom nor tenesmus correlated with volume of rectum treated to at least 90% of the prescribed dose. We conclude that the assessment of the impact of volume on the level of acute symptoms in pelvic radiotherapy is complex, and requires analysis of a range of symptoms, dose levels and normal-tissue volumes. The degree of symptom reduction from conformal radiotherapy will emerge from the RMH randomised trial within the next 12 months.
Humans↗