Ed the r Up the bulk of the persistent TH-302 expression of mutant hEGFR for maintenance of lung tumors. To test if tumors recur after a complete regression, we conducted experiments on long-term doxycycline withdrawal. After 3 weeks of doxycycline withdrawal, was one completely Requests reference requests getting regression of lung tumors was observed, and there was no tumor recurrence with a further 6 weeks of doxycycline withdrawal. This is best CONFIRMS the r Up the bulk of the mutant EGFR in lung tumor maintenance and validated EGFR mutants as good targets for cancer therapies. Compared to the tumors of mice M, Which remained on doxycycline, there was a dramatic decrease in tumor density and cell structure after 1 week of doxycycline withdrawal. There were foci of interstitial thickness increased slightly Ht and cell density, which probably represent the remnants of the tumor after withdrawal of doxycycline. These responses correlated with histological analysis of the MRI tumor regression. No residual tumors in the lungs of three M Bitransgenic mice was found after doxycycline removed from the diet for more than 3 weeks. Along with the rapid regression of tumors after 1 week of doxycycline withdrawal, we observed a decrease of 23 times of 67 Ki-positive tumor cells. To determine whether tumor regression was associated with apoptosis, we performed tests of TUNEL tumor samples from bitransgenic M Mice before and after doxycycline withdrawal. We found a 20-fold increase in TUNEL-positive cells after 1 week of doxycycline withdrawal. In agreement with this showed Western blot analysis using as the total lung lysate after removal of doxycycline, observed a drastic reduction of two total EGFR and activated EGFR in the lungs of Mice bitransgenic. The rapid decline in the level of EGFR protein probably reflects both the decreased transcription of mutant EGFR and a significant reduction in the number of mutant cells as shown EGFRexpressing tumor from histological analyzes.
These data demonstrate a significant reduction in tumor cell proliferation and increasing apoptosis of tumor cells with withdrawal hEGFR mutant expression is associated what the requirement of hEGFR mutant expression for the maintenance of tumors. Mutant lung tumors hEGFR entered Infants are sensitive to treatment with erlotinib or HKI 272 and a L Investigate ngeren course of treatment with cetuximab To the sensitivity of these tumors hEGFR kinase Dom ne mutated lung therapies based specifically on the EGFR differently, we imaged serially, the tumor -bearing M nozzles bitransgenic before and after treatment with either erlotinib, a reversible EGFR inhibitor, HKI or 272, an irreversible EGFR inhibitor. After 8-w Weeks of treatment with doxycycline, bitransgenic CCSP rtTA / Tet-op hEGFR Luc L858R and CCSPrtTA / Tet-op hEGFR Del Luc Mice were imaged with MRI-based tumor burden to be documented. Mice tumor-carrying M Were then orally with erlotinib, HKI 272 or placebo treatment. Both compounds have been through a tube at a dose of 50 mg / kg for 1 week and all the Mice, the werekept with doxycycline w Administered during the study. After 1 week of treatment, obtain bitransgenic Mice Of two lines and either erlotinib or HKI L858R Del 272 showed a significant reduction in tumor mass as documented by MRI staging. These data demonstrate that inhibition of EGFR.