c-Myc is a helix-loop leucine zipper phosphoprotein that heterodimerizes with Max and regulates gene transcription in cell proliferation, cell differentiation, and programmed cell death. Previously, we demonstrated that c-Myc is modified by O-linked N-acetylglucosamine (O-GlcNAc) within or nearby the N-terminal transcriptional activation domain (Chou, T.-Y., Dang, C.V., and Hart, G.W. (1995) Proc. Natl. Acad. Sci. U.S.A. 92, 4417-4421). In this paper, we identified the O-GlcNAc attachment site(s) on c-Myc. c-Myc purified from sf9 insect cells was trypsinized, and its GlcNAc moieties were enzymically labeled with [3H]galactose. The [3H]galactose-labeled glycopeptides were isolated by reverse phase high performance liquid chromatography and then subjected to gas-phase sequencing, manual Edman degradation, and laser desorption/ionization mass spectrometry. These analyses show that threonine 58, an in vivo phosphorylation site in the transactivation domain, is the major O-GlcNAc glycosylation site of c-Myc. Mutation of threonine 58, frequently found in retroviral v-Myc proteins and in human Burkitt and AIDS-related lymphomas, is associated with enhanced transforming activity and tumorigenicity. The reciprocal glycosylation and phosphorylation at this biologically significant amino acid residue may play an important role in the regulation of the functions of c-Myc.

The new adenocarcinoma classification has significant impact on death and recurrence in stage I lung adenocarcinoma. Patients with PL2 and micropapillary/solid predominant pattern have significant higher risk for recurrence. This information is important for patient stratification for aggressive adjuvant chemoradiation therapy.

Purpose: Mutations in epidermal growth factor receptor (EGFR) can be used to predict the tumor response of patients receiving gefitinib for non^small cell lung cancer (NSCLC).We investigated the association between mutations in EGFR tyrosine kinase domain and tumor response and survival in gefitinib-treated NSCLC patients. Experimental Design: EGFR mutations in exons 18 to 21were analyzed by DNA sequencing of paraffin-embedded tumor tissues from gefitinib-treated NSCLC patients. The results were correlated with clinical variables. Results: EGFR mutations were found in 61.1% (33 of 54) of cases; response rate and disease control rate were 56.8% and 68.5%, respectively. There was no significant difference in mutation rates between adenocarcinoma (29 of 43) and nonadenocarcinoma (4 of 11; P = 0.085). However, all four nonadenocarcinomas with EGFR mutations had no response to gefitinib. Presence of EGFR mutations was the only independent predictor for disease control (P = 0.003) and tumor response (P = 0.017) in multivariate analysis; positive predictive values were 87.9% and 70.8% and negative predictive values were 61.9% and 69.2%, respectively. In comparison with patients whose tumor was negative for EGFR mutations, patients with EGFR mutations had better progression-free survival (median, 7.6 versus 1.7 months; P = 0.011) and overall survival (median, 14.7 versus 4.7 months; P = 0.046). Conclusions: Mutations in EGFR tyrosine kinase correlate with treatment response and survival in gefitinib-treated NSCLC patients and can be used as a predictive and prognostic factor. Thus, analysis of EGFR tyrosine kinase mutations in lung adenocarcinoma is of clinical significance, as it can permit the customization of treatment with EGFR tyrosine kinase inhibitors.

Introduction:The efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors in EGFR mutation-positive non–small-cell lung cancer (NSCLC) patients necessitates accurate, timely testing. Although EGFR mutation testing has been adopted by many laboratories in Asia, data are lacking on the proportion of NSCLC patients tested in each country, and the most commonly used testing methods.Methods:A retrospective survey of records from NSCLC patients tested for EGFR mutations during 2011 was conducted in 11 Asian Pacific countries at 40 sites that routinely performed EGFR mutation testing during that period. Patient records were used to complete an online questionnaire at each site.Results:Of the 22,193 NSCLC patient records surveyed, 31.8% (95% confidence interval: 31.2%–32.5%) were tested for EGFR mutations. The rate of EGFR mutation positivity was 39.6% among the 10,687 cases tested. The majority of samples were biopsy and/or cytology samples (71.4%). DNA sequencing was the most commonly used testing method accounting for 40% and 32.5% of tissue and cytology samples, respectively. A pathology report was available only to 60.0% of the sites, and 47.5% were not members of a Quality Assurance Scheme.Conclusions:In 2011, EGFR mutation testing practices varied widely across Asia. These data provide a reference platform from which to improve the molecular diagnosis of NSCLC, and EGFR mutation testing in particular, in Asia.