Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P43146 (tumour suppressor)
 5,935 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Erlotinib [Tarceva, R 1415, CP 358774, OSI 774, NSC 718781] is a small molecular, once-a-day, orally active inhibitor of the epidermal growth factor receptor tyrosine kinase. This profile has been selected from R&D Insight, a pharmaceutical intelligence database produced by Adis International Ltd. It is one of a class of anticancer drugs that target the underlying molecular mechanism involving oncogenes and tumour suppressor genes, which play critical roles in the conversion of normal cells into a cancerous state. Erlotinib is undergoing clinical development as an oral tablet by an alliance between OSI Pharmaceuticals, Genentech and Roche. OSI Pharmaceuticals, Genentech and Roche have entered an agreement for the global development and commercialisation of erlotinib. Under the terms of the agreement, Genentech and OSI will share costs and profit-taking for commercialising the product in the US. The overall costs of the development programme will be shared equally between the three companies. OSI will keep certain co-promotion rights in the US and Genentech will be responsible for commercialising the drug in the US should the FDA approve it. Roche will take the responsibility for obtaining regulatory approval and commercialisation in territories outside the US and pay royalties to OSI on net sales of the product in these markets. Initially, the alliance partners intend to pursue development of erlotinib in all the major tumour markets, particularly for non-small cell lung cancer (NSCLC) in which the group will focus on front-line combination approaches. Pfizer and OSI Pharmaceuticals in the US were developing erlotinib as a treatment for solid tumours. However, in June 2000, Pfizer merged with Warner-Lambert. The resulting company retained the Pfizer name, but in order to meet Federal Trade Commission requirements for the merger Pfizer granted all developmental and marketing rights for erlotinib to OSI Pharmaceuticals. This divestiture of the erlotinib portfolio, in effect, gave OSI a royalty-free, cashless license to the drug. In November 2001, OSI announced a partnership deal with HopeLink Corporation, a healthcare information technology company with an Internet-based Clinical Trial Service. The partnership will enable OSI to heighten awareness of its clinical trials and shorten patient accrual times. It will initially involve the presentation of the OSI phase III pancreatic and refractory NSCLC trials via Hopelink's Syndicated Network. In addition to this the two companies have also agreed to develop additional products and service together that will increase the efficiency of the clinical trial process, increase awareness of clinical trials, and enhance patient accrual techniques. OSI has also entered into an agreement with Therradex, a contract research organisation (CRO) to monitor phase II trials for erlotinib in NSCLC, ovarian and head and neck cancer. In addition, OSI entered into an agreement in 2001 with the US NCI. The NCI is conducting trials in a variety of different cancers. A phase III front-line NSCLC trial (TRIBUTE) of erlotinib in combination with carboplatin and paclitaxel was initiated in July 2001. The multicentre study is being conducted by Genentech in 1000 patients in the US, and will determine whether the addition of erlotinib to carboplatin chemotherapy is able to improve the duration of patient survival. Enrolment for this trial was completed in July 2002. An independent Data Monitoring Committee (DMC) has since reviewed the data from the trial and concluded that there are no safety or efficacy concerns that would warrant stopping the trial. However, the DMC did recommend stopping erlotinib at the time of disease progression or at the start of second-line therapy. A front-line phase III study of erlotinib in NSCLC (TALENT) in combination with gemcitabine and cisplatin chemotherapy was initiated by Roche in Europe in November 2001. Enrolment into this study was completed in September 2002, with approximately 1200 patients. Roche has confirmed that the study woulde has confirmed that the study would be included in the alliance's potential regulatory submission for front-line therapy in chemotherapy-naive patients in the US. Data from the trial is expected in the second half of 2003. OSI has opened two additional phase Ib studies to examine the potential of erlotinib in combination with carboplatin and paclitaxel in one study and gemcitabine and cisplatin in the other. A phase I study of erlotinib is also being conducted in patients with lung cancer in Japan. OSI received fast-track status from the US FDA in September 2002 for erlotinib as a second- or third-line treatment for patients with incurable stage IIIB/IV NSCLC who have failed to respond to standard therapy for advanced metastatic disease. Fast-track status was also granted to erlotinib in May 2002 for the treatment of chemotherapy-naive stage III/IV NSCLC. There are important differences between phase III studies of erlotinib and AstraZeneca's direct competitor drug gefitinib, which recently returned disappointing results in a frontline NSCLC trial with combination chemotherapy. In assessing the survival benefit of erlotinib with chemotherapy, the dose employed of 150 mg/day is the maximum tolerated dose (MTD), whereas the gefitinib trials were conducted at relatively lower doses than the MTD determined in earlier phase I studies. OSI is also investigating the survival benefit of erlotinib in a phase III study in refractory NSCLC patients, a key registration study. Patient size of the NSCLC trial was increased from 330 to 700 as OSI shifted emphasis from its pancreatic cancer trials. Phase II development for this indication was initiated based on data from a phase I trial, which had completed patient enrolment by April 2003. OSI and the US NCI signed a collaborative research agreement in 2001. The NCI is developing erlotinib through its CTEP programme for multiple tumour types including epithelial malignancies, gastrointestinal and genitourinary tracts, gynaecological malignancies and brain tumours. OSI supplies erlotinib for the trial, but the NCI provides the funding and manages the trials. A series of approximately ten phase Ib trials are already underway or were set to start in the US in 2001 to determine safety, tolerance and pharmacokinetic parameters of erlotinib in combination with a number of commonly used chemotherapeutic agents. The Wall Street Journal reported on 25 February 2002, that analysts at Robert Stephens, New York, USA, have forecast Tarceva to reach annual sales of >$US1 billion. Other analysts, at Merrill Lynch & Co., have predicted that products belonging to the same class as Tarceva could reach combined worldwide sales of $US6 billion to $US10 billion annually. In an earlier report by the Financial Times on 10 May 2001, it was stated that approximately 12 new anticancer agents are expected to be approved by the FDA through to the end of 2002. These agents, of which Tarceva is one, were said to have the potential to generate total sales of $US2.6 billion. Goldman Sachs have forecast Tarceva to reach peak sales of $US250 million for the indication of head and neck cancer alone. Previously in January 2001, the Financial Times claimed that OSI Pharmaceuticals, one of the development partners for Tarceva, stood to gain $US187 million pending regulatory approval. Genentech and Roche were each said to be buying $US35 million worth of OSI's stock and paying upfront fees. Tarceva is facing competition by two similar compounds, developed by AstraZeneca and ImClone, respectively.
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PMID:Erlotinib: CP 358774, NSC 718781, OSI 774, R 1415. 1284 90

Pancreatic ductal carcinoma still is an aggressive disease with a fatal prognosis due to late diagnosis and resistance to pharmacological and surgical treatments. Molecular investigations of pancreatic cancer are complicated by the restricted accessibility of the organ for biopsies. However, recent studies have indicated that pancreatic cancer is a multi-stage process resulting from the accumulation of genetic changes in the somatic DNA of normal cells. These molecular alterations, including overexpression of receptor-ligand systems, oncogene activation and loss of tumour suppressor genes, leads to a profound disturbance in cell cycle regulation and continuous growth. The molecular findings are now integrated in a pancreatic tumour progression model, with genetically and morphological defined precursor lesions. However, it remains unclear whether the initial target cells of this cancer develop from ductal or acinar cells. This review will present recent emerging questions on the biology of pancreatic cancer with particular emphasis on the cell origin and tumour microenvironment.
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PMID:[Biological aspects of pancreatic cancer]. 1617 78

Treatment options for pancreatic cancer have limited success and it is therefore an appropriate target for the development of new strategies, including gene therapy. Gene therapy approaches include inhibition of activated oncogenes (KRAS, LSM1) with antisense and RNA interference strategies, replacement of inactivated tumour suppressor genes (TP53, CDKN2A, CDKN1A), targeting of cell signalling pathways, gene-directed prodrug-activation therapies and the use of replication-competent oncolytic viruses. Angiogenesis and apoptosis have also been targeted for gene therapy. Clinical trials of gene therapy have shown only moderate anti-tumour effects. As there are many genetic abnormalities in pancreatic cancer, strategies combining different targets or indeed different modalities of treatment, may be more successful. Identification of new targets and improvements in delivery and targeting may further improve the efficacy of gene therapy in pancreatic cancer.
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PMID:Gene therapy developments for pancreatic cancer. 1654 28

SMAD4 (MAD homologue 4 (Drosophila)), also known as DPC4 (deleted in pancreatic cancer), is a tumour suppressor gene that encodes a central mediator of transforming growth factor-beta signalling. Germline mutations in SMAD4 are found in over 50% of patients with familial juvenile polyposis, an autosomal dominant disorder characterized by predisposition to hamartomatous polyps and gastrointestinal cancer. Dense inflammatory cell infiltrates underlay grossly normal appearing, non-polypoid colonic and gastric mucosa of patients with familial juvenile polyposis. This prominent stromal component suggests that loss of SMAD4-dependent signalling in cells within the epithelial microenvironment has an important role in the evolution of intestinal tumorigenesis in this syndrome. Here we show that selective loss of Smad4-dependent signalling in T cells leads to spontaneous epithelial cancers throughout the gastrointestinal tract in mice, whereas epithelial-specific deletion of the Smad4 gene does not. Tumours arising within the colon, rectum, duodenum, stomach and oral cavity are stroma-rich with dense plasma cell infiltrates. Smad4(-/-) T cells produce abundant T(H)2-type cytokines including interleukin (IL)-5, IL-6 and IL-13, known mediators of plasma cell and stromal expansion. The results support the concept that cancer, as an outcome, reflects the loss of the normal communication between the cellular constituents of a given organ, and indicate that Smad4-deficient T cells ultimately send the wrong message to their stromal and epithelial neighbours.
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PMID:Smad4 signalling in T cells is required for suppression of gastrointestinal cancer. 1679 Dec 1

Pancreatic cancer, which is responsible for >90% of exocrine pancreatic tumours, is typically a disease of the elderly (> or =70 years of age). However, older patients are less likely to be staged than younger patients despite having a worse overall 5-year survival rate than their younger counterparts. Various radiological, ultrasonographic and endoscopic investigations are used not only as diagnostic tools but also to accurately stage the cancer for possible surgery. Many patients with pancreatic cancer have mutations of the K-ras oncogene, and various tumour suppressor genes are also inactivated. Pancreas resection can be performed in elderly resectable patients without excess mortality, even in those >80 years of age. However, treatment for locally advanced, unresectable and metastatic pancreatic cancer is palliative. Fluorouracil-based chemoradiation for locally advanced or unresectable cancer, and gemcitabine for patients with metastatic disease, can result in clinical benefits. Placement of a stent in the biliary tract has been shown to improve symptoms of obstructive jaundice or ascites, as well as quality of life. As molecular targets are identified, interventions with targeted specific agents may improve tumour control. However, further studies will be needed to demonstrate whether or not various agents targeting signal transduction pathways or nuclear transcription factors are useful for elderly patients with advanced pancreatic cancer.
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PMID:Current treatment strategies for pancreatic cancer in the elderly. 1682 93

Germline mutations in the tumour suppressor genes breast cancer antigen gene (BRCA)1 and BRCA2 have been proven to portend a drastically increased lifetime risk of breast and ovarian cancers in the individuals who carry them. A number of studies have shown that the third most common cancer associated with these mutations is pancreatic cancer. BRCA1/2 mutations are characterised by "allelic" or "phenotypic" heterogeneity, in that they demonstrate differing cancer expressivity between and within pedigrees that segregate their mutations. If the same mutation is present in all our cells, why do some families with a given mutation display predominantly breast cancer? Why do other lineages show a preponderance of ovarian cancer? And why would some families have members who develop mostly or exclusively pancreatic cancer--a cancer that occurs more commonly in men and that lacks consistent evidence for a hormonal basis to its aetiology--which is clearly the case for breast and ovarian cancer? The answer is that other modifying genetic and environmental factors must interact to preferentially incite carcinogenesis in one organ over another. We are just beginning to elucidate what these factors are.
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PMID:Role of BRCA1 and BRCA2 mutations in pancreatic cancer. 1697 16

Smad4 is a tumour suppressor gene frequently deleted in pancreatic cancer. To investigate the roles of Smad4 deficiency in invasive and matastatic capabilities of pancreatic cancer, we examined the effects of Smad4 deficiency on regulation of the invasion suppressor E-cadherin in pancreatic cancer cell line PANC-1. TGF-beta decreased expression of E-cadherin and beta-catenin proteins at the plasma membrane, increased Snail and Slug mRNA expression, and induced fibroblastoid morphology in PANC-1 cells. These effects of TGF-beta were abrogated in Smad4-knocked-down PANC-1 cells. We also found that TGF-beta-induced down-regulation of E-cadherin expression was partially inhibited in Snail- and Slug-knocked-down PANC-1 cells. Thus, Smad4 mediates down-regulation of E-cadherin induced by TGF-beta in PANC-1 cells, at least in part, through Snail and Slug induction. These results suggest that Smad4 deficiency observed in invasive and metastatic pancreatic cancer might not be linked to the loss of E-cadherin.
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PMID:Smad4 is essential for down-regulation of E-cadherin induced by TGF-beta in pancreatic cancer cell line PANC-1. 1730 Oct 79

The cross-talk between tumour cells and the surrounding supporting host cells (stroma) is a key regulator of cancer growth and progression. By undertaking 2-DE analysis of laser capture microdissected malignant and stromal components of pancreatic tumours and benign ductal elements, we have identified high levels of S100A8 and S100A9 in tumour-associated stroma but not in benign or malignant epithelia. Immunohistochemical analysis (n = 71 patients) revealed strong expression of both proteins in stromal myeloid cells, subsequently identified as CD14(+)/CD68(- )monocytes/macrophages. Co-immunofluorescence revealed that S100A8 was expressed in a subset of S100A9-positive cells. Correlation of the expression of S100A8 and S100A9 to patient parameters revealed that the microenvironments of tumours which lacked expression of the tumour suppressor protein, Smad4, had significantly reduced numbers of S100A8-immunoreactive (p = 0.023) but not S100A9-immunoreactive (p = 0.21) cells. The ratio of S100A8- to S100A9-positive cells within individual tumours was significantly lower in Smad4-negative tumours than in Smad4-positive tumours (p<0.003). Pancreatitic specimens also contained S100A8- and S100A9-expressing cells, although this was not observed in regions displaying extensive fibrosis. In conclusion, our study provides an extensive analysis of S100A8 and S100A9 in pancreatic disease and highlights a potentially important relationship between pancreatic cancer cells and their surrounding microenvironment.
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PMID:The expression of S100A8 in pancreatic cancer-associated monocytes is associated with the Smad4 status of pancreatic cancer cells. 1746 85

MUC4 is a transmembrane mucin expressed in pancreatic ductal adenocarcinoma (DAC) in contrast to normal pancreas, and is an independent predictor of poor prognosis in patients with invasive DAC. Our aim was therefore to investigate the mechanisms that control MUC4 expression in pancreatic cancer cells. We focused our study on activator protein (AP)-2alpha transcription factor that acts as a tumour suppressor gene in several cancers. In a series of 18 human DAC, using immunohistochemistry, we confirmed that MUC4 was exclusively expressed in cancerous or preneoplastic lesions in 83% of the samples. On the contrary, AP-2 was mainly expressed by non-tumoural ductal cells (61%) or endocrine cells (67%). Moreover, MUC4 and AP-2 were never found co-expressed suggesting an inhibitory role of AP-2alpha in normal ductal cells. In CAPAN-1 and CAPAN-2 cells, transient AP-2alpha over-expression decreased both MUC4 mRNA and apomucin levels by 20-40% by a mechanism involving inhibition of MUC4 promoter. By chromatin immunoprecipitation and gel-shift assays, we demonstrated that this inhibition involved two AP-2 cis-elements located in the -475/-238 region of the promoter. CAPAN-1 clones, which stably over-expressed AP-2alpha, displayed a strong MUC4 down-regulation (-38 to -100%), a significant decrease of both cell proliferation and invasion concomitant to the up-regulation of p27 cyclin-dependent kinase inhibitor. In conclusion, our data provide evidence that AP-2alpha is an important in vivo negative regulator of MUC4 expression in human pancreatic tissue and that AP-2alpha may play a tumour-suppressive role in pancreatic DAC.
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PMID:Transcription factor AP-2alpha represses both the mucin MUC4 expression and pancreatic cancer cell proliferation. 1762 92

Ovarian carcinomas with mutations in the tumour suppressor BRCA2 are particularly sensitive to platinum compounds. However, such carcinomas ultimately develop cisplatin resistance. The mechanism of that resistance is largely unknown. Here we show that acquired resistance to cisplatin can be mediated by secondary intragenic mutations in BRCA2 that restore the wild-type BRCA2 reading frame. First, in a cisplatin-resistant BRCA2-mutated breast-cancer cell line, HCC1428, a secondary genetic change in BRCA2 rescued BRCA2 function. Second, cisplatin selection of a BRCA2-mutated pancreatic cancer cell line, Capan-1 (refs 3, 4), led to five different secondary mutations that restored the wild-type BRCA2 reading frame. All clones with secondary mutations were resistant both to cisplatin and to a poly(ADP-ribose) polymerase (PARP) inhibitor (AG14361). Finally, we evaluated recurrent cancers from patients whose primary BRCA2-mutated ovarian carcinomas were treated with cisplatin. The recurrent tumour that acquired cisplatin resistance had undergone reversion of its BRCA2 mutation. Our results suggest that secondary mutations that restore the wild-type BRCA2 reading frame may be a major clinical mediator of acquired resistance to platinum-based chemotherapy.
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PMID:Secondary mutations as a mechanism of cisplatin resistance in BRCA2-mutated cancers. 1830 36


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