Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

When growth is stimulated in normally quiescent hepatocytes, steady-state levels of c-fos, c-myc, and p53 mRNAs increase sequentially and transiently before DNA replication. C-fos mRNA increases almost immediately after partial hepatectomy and decreases by 2 hr; c-myc mRNA reaches maximal levels between 30 min and 2 hr. In contrast, the p53 mRNA increase corresponds to the G1/S transition, and mRNAs from c-ras genes are elevated later, coinciding with DNA replication and mitosis. p53 and p21 proteins are elevated when their mRNAs are more abundant. This regulated response suggests that these genes either control key steps in the cell cycle or are responding to humoral or internal growth factors acting at specified growth stages. We propose that hepatocytes go through a "priming" stage during the first four hours after partial hepatectomy and that their progression through late G1, is likely to be controlled by autocrine or paracrine mechanisms, which may account for the precisely regulated growth of the liver after partial hepatectomy. Transforming growth factor beta (TGF beta) is a potent inhibitor of DNA synthesis in normal hepatocytes in vitro. We show that TGF beta mRNA increases in the regenerating liver at the time of hepatocyte DNA synthesis and mitosis. In normal or regenerating liver, the mRNA for this growth factor is contained in nonparenchymal cells but not in hepatocytes. We suggest that TGF beta may be a component of a paracrine regulatory loop that controls hepatocyte replication.
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PMID:Proto-oncogene expression and growth factors during liver regeneration. 332 11

HMBA induces MEL cells to terminal erythroid differentiation. HMBA causes a decrease in diacylglycerol concentration, a decrease in Ca+2 and phospholipid-dependent protein kinase C activity (within 2 hr). There is an early (within 1-2 hrs) suppression of c-myb and c-myc gene transcription and an increase in c-fos mRNA (within 4 hrs). During the early or "latent" period there is no detectable commitment of MELC to terminal cell division or expression of differentiated genes such as alpha 1 or beta maj globin genes. HMBA-induced commitment to terminal differentiation is detected by 12 hrs and over 95% become committed cells by 48-60 hrs. Commitment is associated with persistent suppression of c-myb gene transcription and elevated levels of c-fos mRNA, whereas the level of c-myc mRNA returns to that of uninduced cells. By 36-48 hrs, transcription of the alpha 1 and beta maj globin genes increases 10-30 fold, and that of rRNA genes is suppressed. Changes in expression of c-myb, c-myc, c-fos and p53 genes that occur early during HMBA-induced differentiation may be important in the multistep process involved in commitment of MEL cells to terminal differentiation. Continued suppression of c-myb gene expression may be required for terminal differentiation of these cells.
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PMID:Induction of transformed cells to terminal differentiation. 332 66

HMBA induces MELC to terminal erythroid differentiation. The mechanism of HMBA action is not known. Culture with HMBA causes changes in gene expression which occur during the early "latent period", that is, prior to commitment to terminal differentiation. The inducer causes a decrease in diacylglycerol concentration, a decrease in Ca+2 and a decrease in phospholipid-dependent protein kinase C activity (within 2 hr) (Figure 2). There is an early suppression (within 1-2 hrs) of c-myb and c-myc gene transcription and an increase in c-fos mRNA (within 4 hrs). HMBA-induced commitment to terminal differentiation is detected by 12 hrs and over 95% become committed cells by 48 to 60 hrs. Commitment is associated with persistent suppression of c-myb gene transcription and elevated levels of c-fos mRNA whereas the level of c-myc mRNA returns to that of uninduced cells. By 36 to 48 hrs, transcription of alpha 1 and beta maj globin genes is increased 10 to 30 fold, while that of rRNA genes is suppressed. It is not yet clear how the protein products of proto-oncogenes elicit or modify cellular responses. Changes in expression of c-myb, c-myc, c-fos and p53 genes which occur during HMBA-induced differentiation, as well as in several other systems, suggest that products of these genes may have a role in regulating expression of multiple genes. One possible application of the established pattern of HMBA-induced modulation of gene expression during MELC differentiation may be in following the effects of cyto-differentiation agents during treatment of cancers. Phase I and Phase II chemical trials have been initiated to evaluate HMBA as a cytodifferentiation agent in human neoplasms (65). For most human tumors, assay for cytologic evidence of induced differentiation is difficult at best. Following the effects of a differentiation inducing agent by determining c-myc, or c-myb, mRNA levels may provide useful indicators of biological activity of HMBA and be a basis for evaluating whether continued administration of the agent is of interest in terms of potential clinical efficacy.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Changes in gene expression during hexamethylene bisacetamide induced erythroleukemia differentiation. 348 Oct 77

When growth is stimulated in the normally quiescent adult rat liver by partial hepatectomy, steady state levels of messenger RNAs (mRNAs) for c-fos, c-myc, and p53 increase sequentially during the prereplicative phase which precedes DNA synthesis. Levels of c-fos mRNA are elevated at least 4-fold within 15 min after partial hepatectomy and decrease rapidly by 2 h; c-myc mRNA reaches maximal levels (5-fold over normal) between 30 min and 2 h after the operation. A second, transient phase of expression for both c-fos and c-myc occurs around 8 h after partial hepatectomy. p53 mRNA levels increase between 8 and 12 h after the operation (5-fold over normal) and are reflected in an elevation of steady state levels of p53 protein between 12 and 15 h after partial hepatectomy. The levels of ras p21 protein increase much later at a time of active DNA replication and cell division. Actinomycin D injected at the time of partial hepatectomy blocks the increase in c-myc at 2 h but has no effect on c-fos mRNA levels. Actinomycin D injected at 6 h only partially blocks the increase in c-myc and p53 mRNA at 8 h but does not affect c-fos mRNA. Our results suggest that the transient and sequential expression of protooncogenes during the prereplicative stage of liver regeneration is likely to reflect events associated with entry and progression of hepatocytes into the cell cycle and can serve as markers for identifying specific humoral factors involved in liver regeneration.
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PMID:Sequential protooncogene expression during rat liver regeneration. 351 91

Expression of the oncogenes c-myc, c-raski, and p53 is studied in normal primary mouse cultures and in two adenovirus-transformed mouse cell lines. In all cases oncogene expression is measured in cells arrested in G1 (or G0 for primary cells) by serum starvation and at different times after cell cycle traverse is stimulated by addition of high serum. For primary mouse cells, c-myc mRNA levels are found to increase four- to six-fold within 1 h of serum addition and then decline by 4 h to nearly the level observed in serum-starved cells. This level is maintained throughout the remainder of the cell cycle. The early induction of c-myc is dependent on serum concentration and is independent of cell density. These results confirm and extend previous observations for primary cells. By contrast, expression of c-raski does not vary at all through the cell cycle and p53 increases with time after mitogenic stimulation. In the adenovirus-transformed cell lines, the regulation of expression of c-myc with respect to the cell cycle is altered. There is an increase in c-myc in S phase cells which is dependent on cell density and the early induction in response to serum addition as seen in primary cells is absent. Expressions of c-raski and p53 are found to show similar profiles to those observed for primary cells.
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PMID:Altered regulation of c-myc expression in adenovirus-transformed cells. 380 68

Radioimmunotherapy (RIT) in breast cancer patients using I-131-chimeric L6 (ChL6) and in human breast cancer xenografts in nude mice using Y-90-1,4,7,10-tetraazacylododecant N,N',N",N"'-tetraacetic acid-peptide ChL6 (Y-90-ChL6) has shown promise. Tumor cell response to low-dose rate (5-25 rads/h) irradiation from Y-90-ChL6 RIT, therefore, was correlated with levels of tumor cell mRNA for selected genes linked to programmed cell death (apoptosis). Three groups of 10-16 mice with 1-2 HBT 3477 xenograft tumors were treated with 100, 150, or 250 microCi Y-90-ChL6. Three tumors were taken before and two tumors each were taken 3, 6, and 24 h after injection of 150 microCi Y-90-ChL6. Tumor expression of mRNA was amplified by PCR for p53, PIC1, c-myc, and transforming growth factor-beta 1; quantitated; and standardized to N-ras. Tumors received radiation doses of 2000, 3000, and 5000 rads, respectively, for the groups of mice that received 100, 150, and 250 microCi Y-90-ChL6, and tumor regression occurred in each group, with mean tumor volumes decreased by 10, 50, and 95% at nadir after Y-90-ChL6 injection. At the highest dose level, 30% of mice had complete remissions, and no treatment deaths occurred, although tumors subsequently recurred. Continuous up-regulation of transforming growth factor-beta 1 and c-myc mRNA expression was observed from 3 to 24 h after treatment. Expression of p53 and PIC1 increased at 3 h and subsequently decreased to the untreated control levels. These observations are consistent with previous observations of early responses of p53 and PIC1 to cellular DNA damage and subsequent G1 cell cycle arrest or apoptosis. Apoptosis-associated gene expression patterns observed in this tumor model provide evidence that changes are initiated in the first 24 h of RIT associated with radiation doses of 100-700 rads. These preliminary data suggest that insight into the molecular basis of RIT-induced tumor regression may be gained by further studies using different radiation doses.
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PMID:Yttrium-90 chimeric L6 therapy of human breast cancer in nude mice and apoptosis-related messenger RNA expression. 749 56

The expression of 6 different oncoproteins and 2 tumour suppressor gene products in the plasma cells of 63 bone marrow samples was used to determine a profile of the oncogenic phenotype of patients with multiple myeloma. Dual label flow cytometry after periodatelysine paraformaldehyde fixation was used to detect cell surface phenotype and intracellular protein expression simultaneously. The normal range for both the incidence and intensity of expression was determined for each protein by analysing plasma cells (high CD38 intensity) in 22 normal bone marrow samples. The percentage of myeloma patients with a greater than normal incidence of plasma cells expressing these proteins was 53% for c-myc, 28% for Rb, 28% for bcl-2, 27% for c-fos, 24% for p53 wild, 22% for p53 mutant, 13% for c-neu and 13% for pan-ras. When a panel of 8 antibodies was used, 82% of the samples (n = 28) had an increased incidence of expression by at least one oncoprotein or tumour suppressor gene product. The 5 patients with a normal incidence of expression of all 8 proteins were in plateau stage and 4 had not received chemotherapy for more than 12 months. The number of patients with an increased incidence of expression by 2 or more oncoproteins was significantly greater (X2 = 9.0; p < 0.005) in progressive disease (55%) than in stable disease (14%) but there was no specific phenotype pattern associated with progressive disease. All 6 oncoproteins and both tumour suppressor gene products had a greater incidence and intensity of expression in progressive than in stable disease. The expression of c-myc oncoprotein correlated with c-myc mRNA expression in the same samples (n = 10) but c-myc did not correlate with either the plasma cell labelling index (r = -0.15) nor serum thymidine kinase (r = 0.10). Our results suggest that there is a heterogeneous, non-systematic but almost universal presence of activated oncogenes and tumour suppressor genes in the plasma cells of patients with multiple myeloma and that disease progression is associated with the accumulation of a variety of secondary genetic changes which confer increased malignant behaviour.
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PMID:The oncoprotein phenotype of plasma cells from patients with multiple myeloma. 769 21

Multiple myeloma (MM) is a malignant proliferation of bone marrow plasma cells. Molecular analyses of the involvement of oncogenes (c-myc, and N- and K-ras genes) and suppressor gene (p53) in pathogenesis of MM have been recently carried out. Relatively high incidence of elevated expression of c-myc mRNA have been found, although the gene rearrangements are very rare. Mutations of N- and K-ras genes have been found in about 1/3 of patients with MM. Point mutations of p53 gene were detected in about 10-20% of patients. The mutations were found in terminal or leukemic phase of the disease. These indicate that oncogenes and suppressor genes are involved in the development and progression of MM.
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PMID:[Molecular analysis of multiple myeloma cells]. 769 86

Gene expression of growth factors including epidermal growth factor (EGF), transforming growth factor alpha (TGF alpha), epidermal growth factor receptor (EGFR), oncogenes such as c-myc, N-ras, c-erbB2 and tumor suppressor gene P53 were studied in 4 human lung cancer cell lines using Northern blot technique. Among these cell lines were 2 adenocarcinoma cell lines, one large cell carcinoma cell line and one small cell carcinoma cell line. Expression of EGF and TGF alpha mRNAs were found in all 4 cell lines and EFGR mRNA was seen in 3 out of 4 cell lines. Among these cell lines, 2 cell lines with weaker expression of EGF and TGF alpha, expressed c-myc mRNA. Another 2 cell lines had no c-myc but expressed large amounts of EGF and TGF alpha mRNA. No expression of N-ras, c-erbB2 and p53 were found in these cell lines. The results indicate the presence of autocrine loop of growth factors in these cancer cells. The autostimulation of growth factors may be the main cause for the uncontrolled growth of cancer cells. After treating the cancer cells with EGF, anti-EGF and anti-EGFR antibodies, EGF was found to exert a mild stimulating effect on the growth of one cell line, but no effect on the other cell lines. Anti-EGF and anti-EGFR antibodies inhibited the cell growth on all cell lines. These results provided further evidence for the presence of autocrine loop of growth factors in these lung cancer cell lines.
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PMID:[Gene expression of growth factors, growth factor receptor and oncogenes in human lung cancer cell lines]. 778 Nov 11

To define the molecular changes occurring in endocrine tumours, we have analysed three human endocrine tumours established in our laboratory: BON, a functioning carcinoid tumour from the pancreas; SIM, a nonfunctioning carcinoid of the ileum; and STAN, a pheochromocytoma. A homozygous point mutation of the N-ras gene was identified at codon 61 in BON cells in conjunction with overexpression of N-ras mRNA and protein. BON cells also exhibited increased expression of c-myc and cdc2 kinase mRNA and protein; TGF-beta 1, p53 and retinoblastoma (RB) mRNA and protein levels were decreased. In addition, increased expression of the mdm2 oncogene and both the truncated and the wild-type RB protein were noted in BON. SIM cells exhibited moderately increased N-ras and c-myc mRNA levels along with decreased levels of RB mRNA and protein. Similar to BON and SIM, analysis of STAN showed increased N-ras and c-myc levels. Our data show multiple molecular changes in the three human endocrine tumours with the BON cell line exhibiting the most dramatic changes. Furthermore, our data suggest the existence of different molecular pathways in the pathogenesis of endocrine tumours. These cell lines will provide unique in vitro models to further analyse the significance of these molecular alterations.
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PMID:Analysis of multiple molecular changes in human endocrine tumours. 795 99


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