Fig 5 - uploaded by William F Dietrich
Content may be subject to copyright.
Source publication
We generated allelotypes of 38 methylene chloride-induced lung carcinomas from female C57BL/6J x C3H/6J F1 (hereafter called B6C3F1) mice. Two or more polymorphic markers per autosome, most of them microsatellites, were examined for loss of heterozygosity. Allelic losses throughout the genome were generally infrequent except for markers on chromoso...
Contexts in source publication
Context 1
... tumors,of which the most prevalent alteration was a G to A transition in the second base of codon 12 (Table 5). Sequencing analysis and SSCA of the spontaneous and methylene chloride-induced tumors with more pronounced imbal ances at D6MJTI4 exhibited weak to almost absent bands representing the normal as compared to the mutated allele (Fig. ...
Context 2
... K-ras proto-oncogene plays an important role during chemically induced and spontaneous carcinogenesis of the murine lung as well as in human lung cancer (4, 5, 23). The normal K-ras allele was reduced relative to the mutant allele or in few cases lost, based on sequencing analysis and SSCA of tumor samples exhibiting more pronounced imbalances (Fig. 5). Unfortunately, it is difficult to differentiate be tween reduction of one allele and amplification of the other allele using microsatellite analysis. Similar results have been reported for B6c3F1 mouse lung tumors. B, analysis of DNA from spontaneous (s) and methylene chloride-induced (m) lung tumors and control DNA (ctr) for allelic ...
Similar publications
Tumorigenesis of head and neck squamous cell carcinomas (HNSCC) is associated with various genetic changes such as loss of heterozygosity (LOH) on human chromosome 18q21. This chromosomal region maps a gene cluster coding for a family of intracellular serine protease inhibitors (serpins), including SERPINB13. As SERPINB13 expression in HNSCC has re...
Mammalian genomes are folded into unique topological structures that undergo precise spatiotemporal restructuring during healthy development. Here, we highlight recent advances in our understanding of how the genome folds inside the 3D nucleus and how these folding patterns are miswired during the onset and progression of mammalian disease states....
Conventional mutation theories do not explain (1) why the karyotypes of metastases are related to those of parental cancers but not to those of metastases of other cancers and (2) why cancers metastasize at rates that often far exceed those of conventional mutations. To answer these questions, we advance here the theory that metastases are autonomo...
ETV1 is overexpressed in a subset of clinical prostate cancers as a fusion transcript with many different partners. However, ETV1 can also be overexpressed as a full-length transcript. Full-length ETV1 protein functions differently from truncated ETV1 produced by fusion genes. In this study we describe the genetic background of full-length ETV1 ove...
FUS1 is a tumor suppressor gene located on human chromosome 3p21, and expression of Fus1 protein is highly regulated at various levels, leading to lost or greatly diminished tumor suppressor function in many lung cancers. Here we show that selected microRNAs (miRNA) interact with the 3'-untranslated region (3'UTR) of FUS1, leading to down-regulatio...
Citations
... We observed frequent DNA copy-number losses in chromosome 4 and gains in chromosome 6 as well as mutations in genes involved in Egfr signaling in lung ACs from both non-irradiated and irradiated mice (Supplementary Fig. S3 (39). Concerning the results for chromosome 4, deletions have also been reported in a putative tumorsuppressor gene in chemically induced or spontaneous mouse lung tumors (40). ...
Lung is one of the high-risk organs for radiation-induced carcinogenesis, but the risk of secondary lung-cancer development after particle-beam therapy and the underlying mechanism(s) remain to be elucidated. To investigate the effects of particle-beam radiation on adjacent normal tissues during cancer therapy, 7-week-old male and female B6C3F1 mice were irradiated with 0.2–4 Gy of gamma rays (for comparison), carbon ions (290 MeV/u, linear energy transfer 13 keV/μm), or fast neutrons (0.05–1 Gy, mean energy, ∼2 MeV), and lung-tumor development was assessed by histopathology. Mice irradiated with ≥2 Gy of carbon ions or ≥0.2 Gy of neutrons developed lung adenocarcinoma (AC) significantly sooner than did non-irradiated mice. The relative biological effectiveness values for carbon ions for lung AC development were 1.07 for male mice and 2.59 for females, and the corresponding values for neutrons were 4.63 and 4.57. Genomic analysis of lung ACs revealed alterations in genes involved in Egfr signaling. Hyperphosphorylation of Erk and a frequent nuclear abnormality (i.e., nuclear groove) were observed in lung ACs of mice irradiated with carbon ions or neutrons compared with ACs from non-irradiated or gamma-ray-irradiated groups. Our data indicate that the induction of lung AC by carbon ions occurred at a rate similar to that for gamma rays in males and approximately 2- to 3-fold greater than that for gamma rays in females. In contrast, the effect of neutrons on lung AC development was approximately 4- to 5-fold greater than that of gamma rays. Our results provide valuable information concerning risk assessment of radiation-induced lung tumors after particle-beam therapy and increase our understanding of the molecular basis of tumor development.
... This may now be explained with a model where Ras signaling requires two Ras-GTP molecules, and therefore heterotypic Ras-GDP:Ras-GTP dimers are incapable of driving oncogenesis [33,64]. Consistent with this explanation, development of mutant Ras-driven tumors is often accompanied with a loss of heterozygosity [103,107,108]. In these cases, loss of the WT RAS allele and protein expression would eliminate nonfunctional Ras-GDP:Ras-GTP heterodimers and promote functional Ras-GTP:Ras-GTP homodimers, thereby enhancing mutant Ras-driven oncogenesis. ...
Formation of Ras multimers, including dimers and nanoclusters, has emerged as an exciting, new front of research in the ‘old’ field of Ras biomedicine. With significant advances made in the past few years, we are beginning to understand the structure of Ras multimers and, albeit preliminary, mechanisms that regulate their formation in vitro and in cells. Here we aim to synthesize the knowledge accrued thus far on Ras multimers, particularly the presence of multiple globular (G-) domain interfaces, and discuss how membrane nanodomain composition and structure would influence Ras multimer formation. We end with some general thoughts on the potential implications of Ras multimers in basic and translational biology.
... Interestingly, wild-type Kras, as well as activated Cas9, were undetectable in these tumour cells (Fig. 2c, Supplementary Fig. 1C). Loss of both the wild-type Kras allele and the adjacent Cas9 allele may be selected for during sarcomagenesis because the wild-type Kras allele can act as a tumour suppressor in the presence of an oncogenic Kras that drives transformation and tumorigenesis [28][29][30] . Similar to sarcomas generated in Ad-Cre injected KP mice 31 , immunohistochemical analysis of 12 Ad-P-Cre-induced tumours demonstrated that the majority of tumours (n ¼ 10) are UPS without myogenic staining, whereas a minority (n ¼ 2) were myogenic UPS (Fig. 2d,e). ...
Genetically engineered mouse models that employ site-specific recombinase technology are important tools for cancer research but can be costly and time-consuming. The CRISPR-Cas9 system has been adapted to generate autochthonous tumours in mice, but how these tumours compare to tumours generated by conventional recombinase technology remains to be fully explored. Here we use CRISPR-Cas9 to generate multiple subtypes of primary sarcomas efficiently in wild type and genetically engineered mice. These data demonstrate that CRISPR-Cas9 can be used to generate multiple subtypes of soft tissue sarcomas in mice. Primary sarcomas generated with CRISPR-Cas9 and Cre recombinase technology had similar histology, growth kinetics, copy number variation and mutational load as assessed by whole exome sequencing. These results show that sarcomas generated with CRISPR-Cas9 technology are similar to sarcomas generated with conventional modelling techniques and suggest that CRISPR-Cas9 can be used to more rapidly generate genotypically and phenotypically similar cancers.
... Allelic loss of the p16 tumor suppressor gene occurs in approximately 50% of mouse lung adenocarcinomas [9]. Allelic of chromosomes 1, 4, 11, 12, and 14 are frequently associated with mouse lung tumor development [9][10][11]. Recently, mouse lung tumor susceptibility loci have been linked to chromosomes 6, 9, 17, and 19. ...
Phylogenetic trees symbolizes the progression relationship between biological genre and organisms. The construction of phylogenetic trees support on the similarities or dissimilarity of their physical or inherited features. Accepted dawns of constructing phylogenetic trees mainly focus on substantial characteristics. The current appropriation of high-throughput knowledge has advanced to buildup of large quantity of biological data, which in turn enhance the approach of biological studies in a mixture of approaches. This work is mainly focus on constructing the phylogentic tree for Lung cancer genes of Mouse based on experimental values. Here to construct the phylogenetic tree by applying the cluster and by using JavaTree approaches on several genes differential expressed data. These results are shown the better evolutionary relationship among the Lung cancer genes biological datasets proving that similarity with Human lung cancer genes.
... Specifically, oncogenic Ras can induce a senescent growth arrest when expressed in normal cells [11] and inhibit tumor formation [12], suggesting a tumor suppressive role for the wild-type Ras proteins. In agreement, carcinogen-induced oncogenic mutations in Kras or Hras in lung and skin tumors of mice are often accompanied by loss of the reciprocal wild-type allele [13][14][15]. Similarly, loss of heterozygosity of the oncogenic RAS gene has been reported in human cancers [16]. ...
Oncogenic, activating mutations in KRAS initiate pancreatic cancer. There are, however, two other Ras family members, Nras and Hras, which can be activated in the presence of oncogenic Kras. The role of these wild-type Ras proteins in cancer remains unclear, as their disruption has been shown to enhance or inhibit tumorigenesis depending upon the context. As pancreatic cancer is critically dependent upon Ras signaling, we tested and now report that loss of Hras increases tumor load and reduces survival in an oncogenic Kras-driven pancreatic adenocarcinoma mouse model. These effects were traced to the earliest stages of pancreatic cancer, suggesting that wild-type Hras may suppress tumor initiation. In normal cells, activated Ras can suppress proliferation through p53-dependent mechanisms. We find that the tumor suppressive effects of Hras are nullified in a homozygous mutant p53 background. As such, loss of wild-type Hras fosters the earliest stages of pancreatic cancer in a p53-dependent manner.
... The requirement of two Ras-GTP molecules to make an active Ras dimer may also help explain a long-standing observation in vivo that wild type Ras can act as a tumor suppressor in cells with heterozygous Ras mutations [32,[101][102][103]. Cells often do not become transformed when they acquire an activating mutation in just one endogenous Ras allele but instead do so until they acquire an activating mutation in or lose the second, wild type Ras allele [104,105]. This is in accordance with observations that, despite the high incidence of cells harboring KRas mutations in healthy individuals, only a very small fraction actually develops into cancers, thus suggesting that only cells with KRas-GTP levels above a certain threshold (to make sufficient Ras-GTP dimers) could initiate oncogenesis [106]. ...
The K-, N-, and HRas small GTPases are key regulators of cell physiology and are frequently mutated in human cancers. Despite intensive research, previous efforts to target hyperactive Ras based on known mechanisms of Ras signaling have been met with little success. Several studies have provided compelling evidence for the existence and biological relevance of Ras dimers, establishing a new mechanism for regulating Ras activity in cells additionally to GTP-loading and membrane localization. Existing data also start to reveal how Ras proteins dimerize on the membrane. We propose a dimer model to describe Ras-mediated effector activation, which contrasts existing models of Ras signaling as a monomer or as a 5-8 membered multimer. We also discuss potential implications of this model in both basic and translational Ras biology.
... In the two lines with copy-number loss, KRAS was mutated. Previously published data indicate that an absence of the normal allele facilitates transformation by oncogenic KRAS (V12) and has the phenotypic effect of a KRAS (V12) gain (Hegi et al, 1994). In our studies, the two cell lines with KRAS loss were as resistant as those with a KRAS gains. ...
Background:
To study the molecular mechanism regulating sensitivity to MEK inhibition in pancreatic cancer cell lines.
Methods:
A growth inhibition assay determined sensitivity to MEK162 in a panel of 29 pancreatic cancer cell lines. For the same panel, KRAS mutational status and copy-number variation (CNV) was determine using PCR, array CGH and FISH. Two sensitive and two resistant cell lines were further interrogated for difference in baseline and MEK162-induced gene expression, as well as signal transduction using microarray and western blotting. Cell cycle and apoptosis analysis was measured by flow cytometry.
Results:
We report a strong correlation between both specific KRAS mutational subtype and CNV, and sensitivity to MEK inhibition. Cell lines with a KRAS (V12) mutation and KRAS gains or loss (n=7) are ∼10 times more resistant than those having neither a KRAS (V12) mutation nor KRAS CNV (n=14). Significant differences in baseline and MEK162-induced gene expression exist between the sensitive and resistant lines, especially in genes involved in RAS, EGF receptor and PI3K pathways. This was further supported by difference in signal transduction. MEK 162 blocked ERK1/2, as well as inhibited PI3K and S6 and increased p27KIP1 levels in the sensitive lines.
Conclusions:
Given the potency of MEK162, it may be a promising new therapy for patients with pancreatic cancer and KRAS mutational subtypes, and CNV may serve as important biomarkers for selecting patients that benefit from MEK-targeting based on these preclinical data.
... However, it is becoming increasingly evident that the biological outputs of oncogenic K-Ras are subject to a complex and context-dependent modulation by wild-type Ras proteins. Studies in chemically induced models of lung or skin tumorigenesis have demonstrated that the acquisition of an activating mutation in a KRas or HRas allele is associated with loss of the KRas wild-type or HRas wild-type allele, respectively (Bremner and Balmain, 1990;Hegi et al., 1994;Zhang et al., 2001). Zhang et al. (2001) further demonstrated that loss of the wild-type KRas allele enhanced mutant K-Ras-driven tumorigenesis. ...
Mutations in KRAS are prevalent in human cancers and universally predictive of resistance to anticancer therapeutics. Although it is widely accepted that acquisition of an activating mutation endows RAS genes with functional autonomy, recent studies suggest that the wild-type forms of Ras may contribute to mutant Ras-driven tumorigenesis. Here, we show that downregulation of wild-type H-Ras or N-Ras in mutant K-Ras cancer cells leads to hyperactivation of the Erk/p90RSK and PI3K/Akt pathways and, consequently, the phosphorylation of Chk1 at an inhibitory site, Ser 280. The resulting inhibition of ATR/Chk1 signaling abrogates the activation of the G2 DNA damage checkpoint and confers specific sensitization of mutant K-Ras cancer cells to DNA damage chemotherapeutic agents in vitro and in vivo.
... There is accumulating evidence that WT Ras can behave as a tumour suppressor under certain conditions. Loss of the WT Ras allele is observed in chemically induced tumours that involve NRas [11], HRas [12] and KRas [13] mutations. In addition, the deletion of one WT KRas allele increased the incidence and severity of lung tumours resulting from chemically mutated KRas [14]. ...
The mutant forms of K, N and HRas are known to drive the initiation and progression of a number of human cancers, but less is known about the role of wild-type (WT) Ras alleles and isoforms in this process. We used zinc finger nucleases targeting HRas and NRas to modify both alleles of these genes in the mutant KRas-driven Hec1A endometrial cancer cell line, which normally expresses WT copies of these genes. The disruption of either WT isoform of Ras compromised growth factor-dependent signaling through the ERK pathway. In addition, the disruption of HRas hindered the activation of Akt and subsequent downstream signaling. This was associated with decreased proliferation, increased apoptosis, and decreased anchorage-independent growth in the HRas-disrupted cells. However, xenograft tumor growth was not significantly affected by the disruption of either NRas or HRas. As expected, deleting the mutant allele of KRas abolished tumor growth, whereas deletion of the remaining WT copy of KRas increased the tumorigenic properties of these cells; deleting a single copy of either HRas or NRas did not mimic this effect. This study demonstrates that the WT copies of H, N and KRas play unique roles in the context of mutant KRas-driven tumors.
... The absence of increased LOH at other chromosomal arm strongly supports that the LOH at KRAS is not simply a manifestation of increased genomic stability during progression. Previous studies proposed that a wild-type allele of Kras allele can serve as a tumor-suppressor [7,12,[27][28][29][30]. Our data demonstrate that sporadic loss of the wild-type Kras allele occurred in pancreatic tumors and metastases in both mice and humans. ...
Inactivation of tumor suppressor gene p16/INK4A and oncogenic activation of KRAS occur in almost all pancreatic cancers. To better understand the roles of p16 in pancreatic tumorigenesis, we created a conditional p16 knockout mouse line (p16flox/flox), in which p16 is specifically disrupted in a tissue-specific manner without affecting p19/ARF expression. p16flox/flox; LSL-KrasG12D; Pdx1-Cre mice developed the full spectrum of pancreatic intraepithelial neoplasia (mPanIN) lesions, pancreatic ductal adenocarcinoma (PDA), and metastases were observed in all the mice. Here we report a mouse model that simulates human pancreatic tumorigenesis at both genetic and histologic levels and is ideal for studies of metastasis. During the progression from primary tumors to metastases, the wild-type allele of Kras was progressively lost (loss of heterozygosity at Kras or LOH at Kras) in p16flox/flox; LSL- KrasG12D; Pdx1-Cre mice. These observations suggest a role for Kras beyond tumor initiation. In vitro assays performed with cancer cell lines derived from primary pancreatic tumors of these mice showed that cancer cells with LOH at Kras exhibited more aggressive phenotypes than those retained the wild-type Kras allele, indicating that LOH at Kras can provide cancer cells functional growth advantages and promote metastasis. Increased LOH at KRAS was also observed in progression of human pancreatic primary tumors to metastases, again supporting a role for the KRAS gene in cancer metastasis. This finding has potential translational implications- future KRAS target therapies may need to consider targeting oncogenic KRAS specifically without inhibiting wild-type KRAS function.
