Treatment results and prognostic factors of patients undergoing postoperative radiotherapy for laryngeal squamous cell carcinoma / 癌症

Postoperative radiotherapy (PRT) is widely advocated for patients with squamous cell carcinomas of the head and neck that are considered to be at high risk of recurrence after surgical resection. The aims of this study were to evaluate the treatment outcomes of PRT for patients with laryngeal carcinoma and to identify the value of several prognostic factors. We reviewed the records of 256 patients treated for laryngeal squamous cell carcinoma between January 1993 and December 2005. Disease-free survival (DFS) and overall survival (OS) were estimated using the Kaplan-Meier method. Log-rank test was employed to identify significant prognostic factors for DFS and OS. The Cox proportional hazards model was applied to identify covariates significantly associated with the aforementioned endpoints. Our results showed the 3-, 5-, and 10-year DFS for all patients were 69.9%, 59.5%, and 34.9%, respectively. The 3-, 5-, and 10-year OS rates were 80.8%, 68.6%, and 38.8%, respectively. Significant prognostic factors for both DFS and OS on univariate analysis were grade, primary site, T stage, N stage, overall stage, lymph node metastasis, overall treatment times of radiation, the interval between surgery and radiotherapy, and radiotherapy equipment. Favorable prognostic factors for both DFS and OS on multivariate analysis were lower overall stage, no cervical lymph node metastasis, and using 60Co as radiotherapy equipment. In conclusion, our data suggest that lower overall stage, no cervical lymph node metastasis, and using 60Co as radiotherapy equipment are favorable prognostic factors for DFS and OS and that reducing the overall treatment times of radiation to 6 weeks or less and the interval between surgery and radiotherapy to less than 3 weeks are simple measures to remarkably improve treatment outcome.

Insulin-like growth factor-I inhibits dexamethasone-induced proteolysis in cultured L6 myotubes through PI3K/Akt/GSK-3beta and PI3K/Akt/mTOR-dependent mechanisms.

We and others reported previously that IGF-I inhibits dexamethasone-induced proteolysis in cultured L6 myotubes. Recent evidence suggests that this effect of IGF-I at least in part reflects PI3K/Akt-mediated inhibition of Foxo transcription factors. The potential role of other mechanisms, downstream of PI3K/Akt, is not well understood. Here we tested the hypothesis that PI3K/Akt-mediated inactivation of GSK-3beta and activation of mTOR contribute to the anabolic effects of IGF-I in dexamethasone-treated myotubes. Cultured L6 myotubes were treated with 1 microM dexamethasone in the absence or presence of 0.1 microg/ml of IGF-I and inhibitors of GSK-3beta and mTOR. Protein degradation was measured by determining the release of trichloroacetic acid soluble radioactivity from myotubes that had been prelabeled with (3)H-tyrosine for 48 h. IGF-I reduced basal protein breakdown rates and completely abolished the dexamethasone-induced increase in myotube proteolysis. These effects of IGF-I were associated with increased phosphorylation of Akt, GSK-3beta, and the mTOR downstream targets p70(S6K) and 4E-BP1. The PI3K inhibitor LY294002 and the mTOR inhibitor rapamycin reversed the anabolic effect of IGF-I in dexamethasone-treated myotubes. In addition, the GSK-3beta inhibitors LiCl and TDZD-8 reduced protein degradation in a similar fashion as IGF-I. Our results suggest that PI3K/Akt-mediated inactivation of GSK-3beta and activation of mTOR contribute to the anabolic effects of IGF-I in dexamethasone-treated myotubes.

Protein breakdown in muscle from burned rats is blocked by insulin-like growth factor i and glycogen synthase kinase-3beta inhibitors.

We reported previously that IGF-I inhibits burn-induced muscle proteolysis. Recent studies suggest that activation of the phosphotidylinositol 3-kinase (PI3K)/Akt signaling pathway with downstream phosphorylation of Forkhead box O transcription factors is an important mechanism of IGF-I-induced anabolic effects in skeletal muscle. The potential roles of other mechanisms in the anabolic effects of IGF-I are less well understood. In this study we tested the roles of mammalian target of rapamycin and glycogen synthase kinase-3beta (GSK-3beta) phosphorylation as well as MAPK- and calcineurin-dependent signaling pathways in the anticatabolic effects of IGF-I by incubating extensor digitorum longus muscles from burned rats in the presence of IGF-I and specific signaling pathway inhibitors. Surprisingly, the PI3K inhibitors LY294002 and wortmannin reduced basal protein breakdown. No additional inhibition by IGF-I was noticed in the presence of LY294002 or wortmannin. Inhibition of proteolysis by IGF-I was associated with phosphorylation (inactivation) of GSK-3beta. In addition, the GSK-3beta inhibitors, lithium chloride and thiadiazolidinone-8, reduced protein breakdown in a similar fashion as IGF-I. Lithium chloride, but not thiadiazolidinone-8, increased the levels of phosphorylated Foxo 1 in incubated muscles from burned rats. Inhibitors of mammalian target of rapamycin, MAPK, and calcineurin did not prevent the IGF-I-induced inhibition of muscle proteolysis. Our results suggest that IGF-I inhibits protein breakdown at least in part through a PI3K/Akt/GSK3beta-dependent mechanism. Additional experiments showed that similar mechanisms were responsible for the effect of IGF-I in muscle from nonburned rats. Taken together with recent reports in the literature, the present results suggest that IGF-I inhibits protein breakdown in skeletal muscle by multiple mechanisms, including PI3K/Akt-mediated inactivation of GSK-3beta and Foxo transcription factors.

Insulin-like growth factor-I blocks dexamethasone-induced protein degradation in cultured myotubes by inhibiting multiple proteolytic pathways: 2002 ABA paper.

In previous studies, insulin-like growth factor-I (IGF-I) inhibited glucocorticoid-induced muscle protein breakdown, but the intracellular mechanisms of this effect of IGF-I are not well understood. The purpose of the present study was to test the hypothesis that IGF-I inhibits multiple proteolytic pathways in dexamethasone-treated cultured L6 myotubes. Myotubes were treated with 1 microM dexamethasone for 6 hours in the absence or presence of 0.1 microg/ml of IGF-I. Protein degradation was determined by measuring the release of trichloroacetic acid-soluble radioactivity from proteins prelabeled with 3H-tyrosine. The contribution of lysosomal, proteasomal-dependent, and calpain-dependent proteolysis to the inhibitory effect of IGF-I on protein degradation was assessed by using inhibitors of the individual proteolytic pathways (methylamine, beta-lactone, and E64, respectively). In addition, the influence of IGF-I on cathepsin B, proteasome, and calpain activities was determined. Treatment of L6 myotubes with dexamethasone resulted in an approximately 20% increase in protein degradation. This effect of dexamethasone was completely blocked by IGF-I. When the different protease inhibitors were used, results showed that IGF-I inhibited lysosomal, proteasomal-dependent, and calpain-dependent proteolysis by 70, 44, and 41%, respectively. Additionally, IGF-I blocked the dexamethasone-induced increase in cathepsin B, proteasome, and calpain activities. The present results suggest that IGF-I inhibits glucocorticoid-induced muscle proteolysis by blocking multiple proteolytic pathways.

Insulin-like growth factor-I inhibits lysosomal and proteasome-dependent proteolysis in skeletal muscle after burn injury.

Previous studies suggest that insulin-like growth factor-I (IGF-I) inhibits burn-induced muscle wasting mainly by reducing muscle protein degradation. The intracellular mechanisms of this effect of IGF-I are not known. In the present study, we examined the influence of IGF-I on individual proteolytic pathways in muscles from burned rats. Extensor digitorum longus muscles from burned rats were incubated with specific blockers of lysosomal, calcium-calpain-dependent, and ubiquitin-proteasome-dependent proteolytic pathways in the absence or presence of IGF-I. In addition, cathepsin B and L activities and 20S proteasome activity were determined. IGF-I inhibited lysosomal and ubiquitin-proteasome-dependent protein breakdown in skeletal muscle from burned rats by 70 and 90%, respectively, but did not influence calcium-calpain-dependent protein breakdown. The hormone blocked the burn-induced increase in cathepsin B and L activities but did not reduce 20S proteasome activity. Results are important because they provide novel information about intracellular mechanisms by which IGF-I inhibits the catabolic response to burn injury in skeletal muscle.

Changes in bone marrow-derived myeloid cells from thermally injured rats reflect changes in the progenitor cell population.

Bone marrow progenitor cells develop into mature tissue myeloid cells under the influence of colony-stimulating factors. Cytokines that are elevated post-thermal injury have been shown to influence this process. We hypothesize that thermal injury alters myelopoiesis at the level of the progenitor cell. These differences should be visible after in vitro cultures that include colony-stimulating factors. Prior to culture, bone marrow at postburn day 1 (PBD1) was assessed for cell surface markers and the levels of myeloid progenitors. After culture in granulocyte/macrophage-stimulating colony-stimulating factor, the cell surface markers of the cultured cells were determined. PBD1 marrow from thermally injured rats had more progenitor cells responsive to granulocyte/macrophage-stimulating colony-stimulating factor than did sham. Cultured PBD1 marrow produced more CD90(br) MY(br) CD45(dim) CD4(-) MHCII(-) CD11b(dim) eosinophils than did sham. Cultured bone marrow from thermally injured animals produces myeloid cells with an altered phenotype. Similar changes in myelopoiesis may take place in vivo.

Effect of in vivo infusion of granulocyte colony-stimulating factor on immune function.

As the applications of hematopoietic growth factors increase, their complex impact on host defense and immune responses continues to unfold. The effect of the administration of granulocyte colony-stimulating factor (G-CSF) on bacterial defense, proliferation of lymphocytes, and cytokine production by lymphocytes and peripheral blood mononuclear cells (PBMC) was studied. The effect of G-CSF administration on the phenotype of the cells in the major hematopoietic organs was studied as well. ACI rats were given 10 mg/kg/day G-CSF or vehicle daily for 4 days. Isolated bone marrow neutrophils and enterocytes from treated animals showed a greater bactericidal activity than controls. Proliferation of mitogen-stimulated lymphocytes and PBMC was reduced in G-CSF-treated animals. The production of proinflammatory cytokines, tumor necrosis factor (TNF), and interleukin 6 (IL-6) by lymphocytes and PBMC was reduced by G-CSF pretreatment. G-CSF administration caused an increase in IL-4 (Th2 cytokine) release and a decrease in interferon-gamma (IFNgamma, Th1 cytokine) release by mitogen-stimulated lymphocytes. Cytometric analysis of cells in the progenitor cell region indicated a large increase in immature cells in the bone marrow of G-CSF-treated animals compared with sham along with an increase in B cells and a decrease in polymorphonuclear leukocytes (PMNs). In addition, cytometric analysis showed a large increase in PMNs in blood and splenocytes of the treated animals compared with sham. This study confirms and extends previous observations that G-CSF administration has a number of effects that might simultaneously enhance host defense while reducing the risk of developing uncontrolled systemic inflammation. This may also be efficacious in prolonging graft survival and reducing graft vs. host disease.