Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Clinical resistance to chemotherapeutic drugs is an important problem in the treatment of cancer; the circumvention of resistance has become one of the basic goals of cancer therapy. The most frequent form of primary liver cancer is hepatocellular carcinoma, which is essentially refractory to chemotherapy. We earlier showed that TT-232, a new somatostatin analogue developed in our laboratory, exerted a strong antiproliferative effect both in vitro and in vivo, but no growth hormone release inhibitory or antisecretory activity. Here we report that TT-232 has a pronounced antiproliferative effect on differentiated and dedifferentiated, drug-sensitive and multidrug-resistant hepatocellular carcinoma cell lines. TT-232 induces apoptosis at comparable levels in all these hepatoma variants demonstrating that the multidrug resistance of hepatomas does not correlate with a reduced susceptibility to apoptosis induction. These results clearly reveal that the machinery involved in apoptosis is functional in both drug-sensitive and resistant hepatoma variants and can be activated by the somatostatin analogue TT-232.
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PMID:Apoptosis is induced in both drug-sensitive and multidrug-resistant hepatoma cells by somatostatin analogue TT-232. 1037 72

During catabolic diseases such as sepsis, inflammation, and infection, a state of growth hormone (GH) resistance develops in liver. This has been attributed in part to increased production of the proinflammatory cytokine interleukin-1beta (IL-1beta). To determine how IL-1beta induces GH resistance, we studied the acid-labile subunit (ALS) gene whose hepatic transcription is increased by GH via the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway. IL-1beta reduced the ability of GH to stimulate ALS mRNA in rat primary hepatocytes and ALS promoter activity in H4-II-E rat hepatoma cells. This inhibition was dependent on ALSGAS1, an element resembling a gamma-interferon activated sequence that mediates the transcriptional effects of GH. Inhibition by IL-1beta was also associated with a reduction of GH-dependent binding of STAT5 to this element after chronic (8 and 24 h), but not after acute treatment (15 min). Because these results indicated that the inhibition by IL-1beta was indirect, expression of the recently discovered suppressors of cytokine action (SOCS) was examined in liver cells. IL-1beta did not alter the expression of SOCS1, SOCS2, and CIS, indicating that they are not involved. In contrast, IL-1beta increased SOCS3 mRNA by 8-fold after 24 h of treatment, whereas GH had no effect. Forced expression of SOCS3 was just as effective as IL-1beta in reducing the GH induction of ALS promoter activity in H4-II-E rat hepatoma cells. Similar results were observed in primary rat hepatocytes. We conclude that the induction of SOCS3 by IL-1beta contributes to the development of GH resistance in liver, and represents a mechanism by which cytokines such as IL-1beta cross-talk with cytokines using the JAK-STAT pathway.
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PMID:Role of the suppressor of cytokine signaling-3 in mediating the inhibitory effects of interleukin-1beta on the growth hormone-dependent transcription of the acid-labile subunit gene in liver cells. 1066 May 35

After birth, the acid-labile subunit (ALS) associates in the circulation with insulin-like growth factor (IGF)-I or -II and with IGF binding protein-3 (IGFBP-3) to form a 150-kilodalton complex. This association leads to the retention of IGFs in the vascular system and promotes their endocrine actions. ALS is synthesized almost exclusively in liver, and both hepatic ALS mRNA and circulating levels are increased by growth hormone (GH). Three major areas of study were pursued to better understand the regulation of ALS synthesis and its role in the circulating IGF system. First, the mouse ALS gene was isolated and shown to be organized into two exons and a single intron on chromosome 17. Second, using transient transfection studies in the rat H4-II-E hepatoma cell line and primary rat hepatocytes, the region of the mouse promoter that is responsive to GH was mapped to a nine-base pair cis-element resembling a gamma-interferon-activated sequence. The activation of the mouse ALS gene by GH is mediated by the binding of STAT5 isoforms to this sequence. Finally, an ALS knockout model was created by inactivating the ALS gene in mouse embryonic stem cells. Mice that are homozygous for the mutation grow at a slower rate after birth. This growth depression is associated with large decreases in the plasma concentrations of both IGF-I and IGFBP-3, indicating the critical role of ALS in the regulation of circulating levels of these proteins. Studies of this model will lead to a better understanding of the circulating IGF system.
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PMID:Regulation and role of the acid-labile subunit of the 150-kilodalton insulin-like growth factor complex in the mouse. 1091 19

Insulin resistance contributes to a number of metabolic disorders, including type II diabetes, hypertension, and atherosclerosis. Cytokines, such as tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6, and hormones, such as growth hormone, are known to cause insulin resistance, but the mechanisms by which they inhibit the cellular response to insulin have not been elucidated. One mechanism by which these agents could cause insulin resistance is by inducing the expression of cellular proteins that inhibit insulin receptor (IR) signaling. Suppressors of cytokine signaling (SOCS) proteins are negative regulators of cytokine signaling pathways, the expression of which is regulated by certain cytokines. SOCS proteins are therefore attractive candidates as mediators of cytokine-induced insulin resistance. We have found that SOCS-1 and SOCS-6 interact with the IR when expressed in human hepatoma cells (HepG2) or in rat hepatoma cells overexpressing the human IR. In SOCS-1-expressing cells, insulin treatment increases the extent of interaction with the IR, whereas in SOCS-6-expressing cells the association with the IR appears to require insulin treatment. SOCS-1 and SOCS-6 do not inhibit insulin-dependent IR autophosphorylation, but both proteins inhibit insulin-dependent activation of ERK1/2 and protein kinase B in vivo and IR-directed phosphorylation of IRS-1 in vitro. These results suggest that SOCS proteins may be inhibitors of IR signaling and could mediate cytokine-induced insulin resistance and contribute to the pathogenesis of type II diabetes.
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PMID:Suppressors of cytokine signaling-1 and -6 associate with and inhibit the insulin receptor. A potential mechanism for cytokine-mediated insulin resistance. 1134 31

Insulin-like growth factor (IGF) binding protein-3 (IGFBP-3) is a growth hormone (GH) dependent carrier of the IGFs in human serum. Apart from GH regulation the hormonal control of IGFBP-3 production is not well established and although the liver is considered to be the main source of circulating IGFBP-3, there are no in vitro studies of the effect of both insulin and IGFs on the IGFBP-3 produced in human hepatoma cells. The effect of sex hormones as well as cortisol has not been studied. To elucidate this we performed cell culture studies on HepG2 cells in the presence of various effectors. Insulin, IGF-I and IGF-II brought about a 1.5-2-fold enhancement of IGFBP-3 release at 7.5-30 nM concentrations. In contrast, cortisol decreased IGFBP-3 secretion by 30-40% whereas estradiol, tamoxifen and testosterone had no effect at physiological concentrations. We conclude that, in addition to GH, also insulin, IGF-I and IGF-II and glucocorticoids can modulate IGFBP-3 secretion by human hepatoma cells.
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PMID:Factors regulating insulin-like growth factor binding protein-3 secretion from human hepatoma (HepG2) cells. 1156 37

A 36-year-old woman presented with right upper quadrant abdominal pain, weight loss and attacks of severe sweating. She was known to have a chronic hepatitis B infection. A large hepatocellular carcinoma was diagnosed complicated by recurrent episodes of hypoglycaemia. Serum insulin, insulin-like growth factor (IGF-I) and growth hormone levels proved to be low, with increased serum levels of big-IGF-II. This is indicative of non-islet cell tumour hypoglycaemia. The patient received prednisone which resulted in an improvement in the blood glucose values but the morning hypoglycaemia remained, so that nightly intravenous glucose administration continued to be necessary. Therefore, growth hormone was added to the treatment which resulted in a complete disappearance of the hypoglycaemias. The patient died within 6 months of the diagnosis having been established.
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PMID:[Hepatocellular carcinoma complicated by non-islet cell tumor hypoglycemia]. 1203 25

Secretion of growth hormone (GH) in adult male rats is characterized by high peak and undetectable trough levels, both of which are required for male-specific pattern of liver gene expression and GH-induced phosphorylation of STAT5. The present study suggests that regulation of GH receptor (GHR) levels in rat hepatoma cells by repeated GH stimulation determines GH responsiveness via the JAK2/STAT5 pathway. A short exposure to GH rapidly reduced GHR levels which resulted in an equal desensitization of the JAK2/STAT5 pathway. Recovery of GH-induced STAT5 phosphorylation correlated with the time-dependent recovery of GHR levels during incubation in the absence of GH. Acute GH also induced phosphorylation of ERK1/2 and Akt, and this induction was also inhibited by prior exposure to GH. However, unlike the JAK2/STAT5 pathway, the effect of GH to activate the MEK/ERK and phosphatidylinositol 3-kinase/Akt pathways did not recover following prolonged incubation in the absence of GH. Thus, GH administration desensitizes the JAK2/STAT5 pathway, possibly because of down-regulation of GHR, whereas an additional post-receptor mechanism is required for the prolonged refractoriness of the MEK/ERK and phosphatidylinositol 3-kinase/Akt pathways toward a second GH stimulation. Our study suggests that both receptor and post-receptor mechanisms are important in GH-induced homologous desensitization.
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PMID:Growth hormone-induced differential desensitization of STAT5, ERK, and Akt phosphorylation. 1216 50

Although it is well known that transgenic mice that overexpress growth hormone (GH) frequently develop liver tumours, the precise nature of the relationship between the overexpression of GH and hepatocarcinogenesis is not clear. The current study was designed to investigate the relationship between the expression of the GH transgene and changes in hepatocyte morphology and kinetics, prior to and during hepatocarcinogenesis in GH-transgenic mice. In young mice (1-month-old) prior to tumour development, GH protein, as detected by immunohistochemistry, was observed in the cytoplasm of essentially all hepatocytes. In liver tissues of older animals, apoptotic cells and hypertrophic hepatocytes did not express immunoreactive GH, even though GH was expressed strongly in the smaller hepatocytes. A relatively high proportion of large dysplastic hepatocytes (>50 microm) were apoptotic (TUNEL positive), whereas smaller hepatocytes featured more prominently in the proliferative phase, as measured by BrdU incorporation. GH expression in tumour tissue, as detected by immunohistochemistry, was often variable and generally decreased with tumour development. Northern blot analysis showed that equivalent levels of GH mRNA were present in tumour tissue and adjacent liver. However, there was no clear trend when the levels of GH mRNA extracted from adenoma, and hepatocellular carcinoma, were compared. These observations help clarify some of the mechanisms by which GH promotes hepatocarcinogenesis in GH-transgenic mice.
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PMID:Hepatocellular kinetics and the expression of growth hormone (GH) in the livers and liver tumours of GH-transgenic mice. 1216 43

A 64-year-old woman with high serum levels of growth hormone, insulin-like growth factor-I (IGF-I), and alpha-fetoprotein resulting from partially treated acromegaly was found to have a tumor under the left diaphragm. The patient also had a history of type C viral hepatitis. Laparotomy revealed that the tumor was fixed to the diaphragm and connected to the liver and spleen. The tumor was excised with partial resection of the diaphragm, liver, and spleen, and a diagnosis of left-sided pedunculated hepatocellular carcinoma (HCC) was made. Further examination showed a higher level of IGF-I receptor mRNA in the tumor than in the normal liver parenchyma. We believe it is likely that the high serum levels of IGF-I may have played a role in the development of the pedunculated HCC in this patient.
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PMID:Hepatocellular carcinoma in a patient with acromegaly and high serum levels of insulin-like growth factor I: report of a case. 1244 42

Oral estrogen administration attenuates the metabolic action of growth hormone (GH) in humans. To investigate the mechanism involved, we studied the effects of estrogen on GH signaling through Janus kinase (JAK)2 and the signal transducers and activators of transcription (STATs) in HEK293 cells stably expressing the GH receptor (293GHR), HuH7 (hepatoma) and T-47D (breast cancer) cells. 293GHR cells were transiently transfected with an estrogen receptor-alpha expression plasmid and luciferase reporters with binding elements for STAT3 and STAT5 or the beta-casein promoter. GH stimulated the reporter activities by four- to sixfold. Cotreatment with 17beta-estradiol (E(2)) resulted in a dose-dependent reduction in the response of all three reporters to GH to a maximum of 49-66% of control at 100 nM (P < 0.05). No reduction was seen when E(2) was added 1-2 h after GH treatment. Similar inhibitory effects were observed in HuH7 and T-47D cells. E(2) suppressed GH-induced JAK2 phosphorylation, an effect attenuated by actinomycin D, suggesting a requirement for gene expression. Next, we investigated the role of the suppressors of cytokine signaling (SOCS) in E(2) inhibition. E(2) increased the mRNA abundance of SOCS-2 but not SOCS-1 and SOCS-3 in HEK293 cells. The inhibitory effect of E(2) was absent in cells lacking SOCS-2 but not in those lacking SOCS-1 and SOCS-3. In conclusion, estrogen inhibits GH signaling, an action mediated by SOCS-2. This paper provides evidence for regulatory interaction between a sex steroid and the GHJAKSTAT pathway, in which SOCS-2 plays a central mechanistic role.
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PMID:Estrogen inhibits GH signaling by suppressing GH-induced JAK2 phosphorylation, an effect mediated by SOCS-2. 1255 91


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