Project description:The tumor suppressor gene neurofibromin 1 (NF1) is a major regulator of the RAS-MAPK pathway. NF1 mutations occur in lung cancer but were not extensively explored. We hypothesized that NF1-mutated tumors could define a specific population with a distinct clinical and molecular profile. We performed NF1 sequencing using next generation sequencing (NGS) in 154 lung adenocarcinoma surgical specimens with known KRAS, EGFR, TP53, BRAF, HER2, and PIK3CA status, to evaluate the molecular and clinical specificities of NF1-mutated lung cancers. Clinical data were retrospectively collected, and their associations with molecular profiles assessed. In this series, 24 tumors were NF1 mutated (17.5%) and 11 were NF1 deleted (8%). There was no mutation hotspot. NF1 mutations were rarely associated with other RAS-MAPK pathway mutations. Most of patients with NF1 alterations were males (74.3%) and smokers (74.3%). Overall survival and disease-free survival were statistically better in patients with NF1 alterations (N = 34) than in patients with KRAS mutations (N = 30) in univariate analysis. Our results confirm that NF1 is frequently mutated and represents a distinct molecular and clinical subtype of lung adenocarcinoma.
Project description:Ovarian serous carcinoma (OSC) is the most common and lethal histologic type of ovarian epithelial malignancy. Mutations of TP53 and dysfunction of the Brca1 and/or Brca2 tumor-suppressor proteins have been implicated in the molecular pathogenesis of a large fraction of OSCs, but frequent somatic mutations in other well-established tumor-suppressor genes have not been identified. Using a genome-wide screen of DNA copy number alterations in 36 primary OSCs, we identified two tumors with apparent homozygous deletions of the NF1 gene. Subsequently, 18 ovarian carcinoma-derived cell lines and 41 primary OSCs were evaluated for NF1 alterations. Markedly reduced or absent expression of Nf1 protein was observed in 6 of the 18 cell lines, and using the protein truncation test and sequencing of cDNA and genomic DNA, NF1 mutations resulting in deletion of exons and/or aberrant splicing of NF1 transcripts were detected in 5 of the 6 cell lines with loss of NF1 expression. Similarly, NF1 alterations including homozygous deletions and splicing mutations were identified in 9 (22%) of 41 primary OSCs. As expected, tumors and cell lines with NF1 defects lacked mutations in KRAS or BRAF but showed Ras pathway activation based on immunohistochemical detection of phosphorylated MAPK (primary tumors) or increased levels of GTP-bound Ras (cell lines). The TP53 tumor-suppressor gene was mutated in all OSCs with documented NF1 mutation, suggesting that the pathways regulated by these two tumor-suppressor proteins often cooperate in the development of ovarian carcinomas with serous differentiation.
Project description:Mutations in KRAS and TP53 are common in colorectal carcinogenesis and are associated with resistance to therapy. Rectal cancers carrying both mutations are less likely to respond to neoadjuvant chemoradiation therapy (CRT) compared with wild-type tumors. Codon-specific KRAS mutations are associated with variable resistance to targeted therapies, but their association with rectal cancer response to CRT remains unclear. Our objective was to establish a correlation between specific KRAS mutations and rectal cancer response to CRT and to investigate if the correlation was related to a different association between KRAS and TP53 mutations.A total of 148 stage II-III rectal cancer patients underwent preoperative CRT followed by surgery. DNA was extracted from pretreatment tumor biopsies and paired normal surgical tissues and KRAS and TP53 genotyping was performed. Specific KRAS mutations were then correlated with tumor response and with concurrent TP53 mutation.A total of 60 patients had KRAS mutation, 12 in codon 13 and 48 in other locations. Also, 80 patients had TP53 mutation; 27 had concurrent KRAS/TP53 mutations. Tumors with any KRAS mutation were less likely to have a pCR compared with wild-type KRAS (p = 0.006). Specifically, no tumors with KRAS codon 13 mutations had a pCR (p = 0.03). Tumors with KRAS codon 13 mutations also had a higher incidence of concurrent TP53 mutation compared with tumors with other KRAS mutations (p = 0.02).Mutations in different KRAS codons may have different effects on rectal cancer resistance to CRT. This variable resistance may be related to a different frequency of TP53 mutations in KRAS mutant tumors.
Project description:While mutations in the KRAS oncogene are among the most prevalent in human cancer, there are few successful treatments to target these tumors. It is also likely that heterogeneity in KRAS-mutant tumor biology significantly contributes to the response to therapy. We hypothesized that the presence of commonly co-occurring mutations in STK11 and TP53 tumor suppressors may represent a significant source of heterogeneity in KRAS-mutant tumors. To address this, we utilized a large cohort of resected tumors from 442 lung adenocarcinoma patients with data including annotation of prevalent driver mutations (KRAS and EGFR) and tumor suppressor mutations (STK11 and TP53), microarray-based gene expression and clinical covariates, including overall survival (OS). Specifically, we determined impact of STK11 and TP53 mutations on a new KRAS mutation-associated gene expression signature as well as previously defined signatures of tumor cell proliferation and immune surveillance responses. Interestingly, STK11, but not TP53 mutations, were associated with highly elevated expression of KRAS mutation-associated genes. Mutations in TP53 and STK11 also impacted tumor biology regardless of KRAS status, with TP53 strongly associated with enhanced proliferation and STK11 with suppression of immune surveillance. These findings illustrate the remarkably distinct ways through which tumor suppressor mutations may contribute to heterogeneity in KRAS-mutant tumor biology. In addition, these studies point to novel associations between gene mutations and immune surveillance that could impact the response to immunotherapy.
Project description:We performed integrated genomic, transcriptomic, and proteomic profiling of 150 pancreatic ductal adenocarcinoma (PDAC) specimens, including samples with characteristic low neoplastic cellularity. Deep whole-exome sequencing revealed recurrent somatic mutations in KRAS, TP53, CDKN2A, SMAD4, RNF43, ARID1A, TGF?R2, GNAS, RREB1, and PBRM1. KRAS wild-type tumors harbored alterations in other oncogenic drivers, including GNAS, BRAF, CTNNB1, and additional RAS pathway genes. A subset of tumors harbored multiple KRAS mutations, with some showing evidence of biallelic mutations. Protein profiling identified a favorable prognosis subset with low epithelial-mesenchymal transition and high MTOR pathway scores. Associations of non-coding RNAs with tumor-specific mRNA subtypes were also identified. Our integrated multi-platform analysis reveals a complex molecular landscape of PDAC and provides a roadmap for precision medicine.
Project description:Small cell neuroendocrine carcinoma (SCNEC) of the uterine cervix is a rare but extremely aggressive tumor. While high-risk human papillomavirus (HPV) is involved at an early stage of oncogenesis in many tumors, additional driving events have been postulated to facilitate the progression of SCNECs. Identification of oncogenic drivers could guide targeted therapy of this neoplasm. Clinicopathologic features of 10 cervical SCNECs are reported. Analyses included immunohistochemical evaluation of p16, p53, synaptophysin, and chromogranin expression; in situ hybridizations and polymerase chain reaction for high-risk HPV and/or HPV 18; and next-generation sequencing based on a 637-gene panel. The patients ranged in age from 28 to 68 years (mean, 45.6?y; median, 40.5?y). All tumors had diffuse p16 and synaptophysin expression. All but 1 tumor was positive for chromogranin (extent of staining ranged from focal to diffuse). HPV 18 was detected in 6 tumors and HPV 35 in 1 tumor. At least 1 driver mutation was detected in 8 tumors. Four cases harbored TP53 somatic mutations, 3 of which correlated with an aberrant p53 staining pattern. Four PIK3CA mutations (p.G106A, p.N345T, p.E545K, and p.E545D) were detected in 3 tumors, 2 of which also harbored TP53 mutations. Oncogenic driver mutations involving KRAS, Erbb2, c-Myc, NOTCH1, BCL6, or NCOA3 were detected in 4 tumors. Mutations in caretaker tumor suppressors PTEN, RB1, BRCA1, BRCA2, and ARID1B were also identified in 4 tumors that commonly coharbored activating oncogenic mutations. Targeted next-generation gene sequencing identified genetic alterations involving the MAPK, PI3K/AKT/mTOR, and TP53/BRCA pathways in SCNECs. The presence of genetic alterations that are amenable to targeted therapy in SCNECs offers the potential for individualized management strategies for treatment of this aggressive tumor.
Project description:Cancer is a complex disease in which cells acquire many genetic and epigenetic alterations. We have examined how three types of alterations, mutations in tumor suppressor genes, changes in an imprinted locus, and polymorphic loci, interact to affect tumor susceptibility in a mouse model of neurofibromatosis type 1 (NF1). Mutations in tumor suppressor genes such as TP53 and in oncogenes such as KRAS have major effects on tumorigenesis due to the central roles of these genes in cell proliferation and cell survival. Imprinted genes expressed from only one parental chromosome affect tumorigenesis if their monoallelic expression is lost or duplicated. Because imprinted loci are within regions deleted or amplified in cancer, the parental origin of genomic rearrangements could affect tumorigenesis. Gene polymorphisms can vary tumor incidence by affecting rate-limiting steps in tumorigenesis within tumor cells or surrounding stroma. In our mouse model of NF1, the incidence of tumors mutant for the tumor suppressor genes Nf1 and Trp53 is strongly modified by a linked imprinted locus acting epistatically on two unlinked polymorphic loci, Nstr1 and Nstr2. This interaction of an imprinted locus and polymorphic susceptibility loci has profound implications for human mapping studies where the parental contribution of alleles is often unknown.
Project description:Mucosal melanoma represents ~1% of all melanomas, frequently having a poor prognosis due to diagnosis at a late stage of disease. Mucosal melanoma differs from cutaneous melanoma not only in terms of poorer clinical outcome but also on the molecular level having e.g. less BRAF and more frequent KIT mutations than cutaneous melanomas. For the majority of mucosal melanomas oncogenic driver mutations remain unknown.In our study, 75 tumor tissues from patients diagnosed with mucosal melanoma were analyzed, applying a targeted next generation sequencing panel covering 29 known recurrently mutated genes in melanoma. NF1 and RAS mutations were identified as the most frequently mutated genes occurring in 18.3% and 16.9% of samples, respectively. Mutations in BRAF were identified in 8.4% and KIT in 7.0% of tumor samples.Our study identifies NF1 as the most frequently occurring driver mutation in mucosal melanoma. RAS alterations, consisting of NRAS and KRAS mutations, were the second most frequent mutation type. BRAF and KIT mutations were rare with frequencies below 10% each. Our data indicate that in mucosal melanomas RAS/NF1 alterations are frequent, implying a significant pathogenetic role for MAPK and potentially PI3K pathway activation in these tumors.
Project description:Current assays for somatic mutation analysis are based on extracts from tissue sections that often contain morphologically heterogeneous neoplastic regions with variable contents of normal stromal and inflammatory cells, obscuring the results of the assays. We have developed an RNA-based in situ mutation assay that targets oncogenic mutations in a multiplex fashion that resolves the heterogeneity of the tissue sample. Activating oncogenic mutations are targets for a new generation of cancer drugs. For anti-EGFR therapy prediction, we demonstrate reliable in situ detection of KRAS mutations in codon 12 and 13 in colon and lung cancers in three different types of routinely processed tissue materials. High-throughput screening of KRAS mutation status was successfully performed on a tissue microarray. Moreover, we show how the patterns of expressed mutated and wild-type alleles can be studied in situ in tumors with complex combinations of mutated EGFR, KRAS and TP53. This in situ method holds great promise as a tool to investigate the role of somatic mutations during tumor progression and for prediction of response to targeted therapy.
