Lung cancer is the leading cause of cancer-related death, and NSCLC constitutes
nearly 85%–90% of all cases. The IRS proteins function as adaptors and transmit
signals from multiple receptors. Upon binding of insulin to the insulin receptor
(IR), IRS1 is phosphorylated at several YXXM motifs creating docking sites for
the binding of PI3Kp85, which activates AKT kinase. Therefore, we thought that
gain of function mutantions of IRS1 could be related to development of lung
cancer. In line with this, we wanted determine whether the IRS1 gene was mutated
in the coding regions surrounding YXXM motifs. We sequenced the coding regions
surrounding YXXM motifs of IRS1 using tumor samples of 42 NSCLC patients and 40
matching controls and found heterozygote p.S668T mutation in nine of 42 samples
and four of nine also had the p.D674H mutation. We generated IRS1 expression
vectors harboring p.S668T, p.D674H and double mutants. Expression of the mutants
differentially affected insulin-induced phosphorylation of IRS1, AKT, ERK, and
STAT3. Also, our mutants induced proliferation, glucose uptake, inhibited the
migration of 293T cells and affected the responsiveness of the cells to
cisplatin and radiation. Our results suggest that these novel mutations play a
role in the phenotype of lung cancer.
LT4 treatment should be stopped after the age of 2 years in infants with SCH without a definite pathology of the thyroid gland to exclude cases with transient hypothyroidism. Additionally, we should consider particularly thyroid gland hypoplasia, and also partial defects in iodide organification in infants with SCH.
Lung cancer is the leading cause of death of both men and women across the world. Overexpression and activating mutations of the epidermal growth factor receptor-1 (EGFR1) are frequently observed and associated with poor prognosis. To inhibit the function of EGFR1, multiple antibodies and small-molecule tyrosine kinase inhibitors (TKI) that target EGFR1 have been developed. Even though some patients respond to these TKI, subsequent studies reveal that this is not the case for all nonsmall cell lung cancer (NSCLC) patients. In this study, we determine whether activation and expression levels of EGFR1, ERK, AKT, STAT3, and TWIST1 are dependent on the activating mutations of EGFR1. Protein lysates and DNA have been isolated from tumor and corresponding normal tissues of 16 NSCLC patients. Genomic-DNA is used to sequence the exons 18, 19, and 21 of EGFR1, and exon 2 of k-RAS. Protein lysates were used to determine the expression or phosphorylation levels of EGFR, STAT3, ERK, AKT, and TWIST1. Our results revealed that 16 tumor samples of NSCLC patients showed no mutation in any of the indicated exons of EGFR1 and k-RAS albeit significant levels of activation or expression of the above-mentined oncogenes. In NSCLC patients, the tumor micro-environment can be as important as the activating mutations of EGFR1. TK therapy may also be considered for patients who show high levels of activation of EGFR1 even in the absence of activating mutations.
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