Analysis of genetic changes in lung tumors showed that the incidence of mutations in the TP53 and KRAS genes and the incidence of LOH in the FHIT gene were significantly greater in smokers versus non-smokers (P < 0.01).
As expected, KRAS mutations were the most common alteration found (63% of cases); however, the distribution of nucleotide position alterations was more similar to that observed in gastrointestinal tumors than other lung tumors.
The RAS signature score is predictive of KRAS mutation status in lung tumors and cell lines with high (> 90%) sensitivity but relatively low (50%) specificity due to samples that have apparent RAS pathway activation in the absence of a KRAS mutation.
Importantly, induction of FOXA3 or SPDEF along with mutant KRAS in lung epithelium was sufficient to develop benign or malignant mucinous lung tumors, respectively, in transgenic mice.
These mutations were reduced by treatment of mice with diallyl sulfone before VC and coincided with a reduction in the number of lung tumors with Kras2 mutations.
Comparison of the K-ras mutations observed in the human lung adenocarcinomas with mutation profiles observed in the mouse lung tumors suggest that bulky hydrophobic DNA adducts may be responsible for the majority of the mutations observed in the activated human K-ras genes.
While 95% of patients were former or current smokers, smoking-related G:C>T:A transversions were significantly less frequent in NRAS-mutated lung tumors than KRAS-mutant non-small cell lung cancer [NSCLC; NRAS: 13% (4/30), KRAS: 66% (1772/2733), P < 0.00000001].
Primer extension assays with purified BALB/cJ and A/J proteins in vitro demonstrate that both forms of Pol iota are active but that they may differ in substrate discrimination, which may affect the formation of Kras2 mutations in mouse lung tumors.
Mutations in the K- ras gene are very common in lung tumours and are implicated in the development of lung cancer, but the timing of their occurrence remains poorly understood.
However, a more rigorous test of the requirement for Notch signaling in lung oncogenesis, crossing the LSL-KRAS(G12D) mouse model with a transgenic with a similarly inducible global dominant-negative suppressor of Notch activity, LSL-DNMAML (dominant-negative mastermind-like), reveals no evidence of Notch pathway requirement for lung tumor initiation or growth in vivo.
In this study, TP53 (exons 5-9) and KRAS (codon 12) were analyzed in primary lung tumors of never (n = 40), former (n = 27), and current smokers (n = 64; mainly heavy smokers).
We examined the KIF5B-RET fusion gene in frozen tissues from 154 surgically resected lung tumors using RT-PCR with direct sequencing and the mutation status of EGFR and KRAS genes using PNA clamping.
Using GEM models, we tested whether PI3'-lipid signaling was limiting for the promotion of KRAS(G12D)-driven lung tumors by inducing the expression of KRAS(G12D) in the absence and presence of the activating PIK3CA(H1047R) mutation.
The incidence of KRAS2 mutations in human compared to mouse lung tumors differed significantly, as did the incidence of Hras and p53 gene mutations in human compared to mouse liver tumors.
The triciribine/tipifarnib synergistic effects are seen with several cancer cell lines including those from breast, leukemia, multiple myeloma and lung tumors with different genetic alterations such as K-Ras, B-Raf, PI3K (phosphoinositide 3-kinase), p53 and pRb mutations, PTEN, pRB and Ink4a deletions, and ErbB receptor overexpression.