Recent allelotyping studies suggest that allelic losses at one or both arms of chromosome 4 are frequent in several tumor
types. Cytogenetic studies of malignant mesothelioma (MM) and comparative ...genomic hybridization analyses of small cell lung
carcinoma (SCLC) suggest that chromosome 4 deletions may also play a role in these tumor types, although these results have
not been confirmed by allelotyping. In an effort to more precisely identify and map the locations of putative tumor suppressor
gene(s) on chromosome 4 involved in the pathogenesis of these tumors, we performed loss of heterozygosity studies using 16
polymorphic microsatellite markers. After precise microdissection of archival surgical cases, we studied DNA obtained from
20 MMs, 21 SCLCs, and 20 non-SCLCs (NSCLCs). In addition, DNA from 14 SCLC and 17 NSCLC cell lines and corresponding B lymphoblastoid
lines were studied. In MM and SCLC, we observed frequent losses at three nonoverlapping regions: ( a ) 4q33–34 (region R1; >80%); ( b ) 4q25–26 (region R2; >60%); and ( c ) 4p15.1–15.3 (region R3; >50%). Losses at these sites occurred at lower frequencies in NSCLC (>20–30%). Data from tumors
and cell lines were similar. In MM and SCLC, the most frequently observed pattern was loss at all three regions. However,
in NSCLC, the most frequent pattern was loss at R3 alone. Our study has delineated three nonoverlapping regions of frequent
deletions on chromosome 4 in MM and SCLC, suggesting that there may be three putative suppressor genes on chromosome 4, the
inactivation of which may be important in the pathogenesis of these tumor types.
Although human lung tumor-derived cell lines play an important role in the investigation of lung cancer biology and genetics,
there is no comprehensive study comparing the genotypic and phenotypic ...properties of lung cancer cell lines with those of
the individual tumors from which they were derived. We compared a variety of properties of 12 human non-small cell lung carcinoma
(NSCLC) cell lines (cultured for a median period of 39 months; range, 12â69) and their corresponding archival tumor tissues.
There was, in general, an excellent concordance between the lung tumor cell lines and their corresponding tumor tissues for
morphology (100%), the presence of aneuploidy (100%), immunohistochemical expression of HER2/neu (100%) and p53 proteins (100%),
loss of heterozygosity at 13 chromosomal regions analyzed (97%) using 37 microsatellite markers, microsatellite alterations
(MAs, 75%), TP53 (67%), and K- ras (100%) gene mutations. In addition, there was 100% concordance for the parental allele lost in all 115 comparisons of allelic
losses. Some discrepancies were found; more aneuploid subpopulations of cells were detected in the cell lines as well as higher
incidences of TP53 mutations (4 of 10 mutations not found in the tumors) and microsatellite alterations (two cell lines with MAs not detected
in the tumors). Similar loss of heterozygosity frequencies by chromosomal regions and mean fractional allelic loss index were
detected between successfully cultured and 40 uncultured lung tumors (0.45 and 0.49, respectively), indicating that both groups
were similar. Our findings indicate that the NSCLC cell lines in the large majority of instances retain the properties of
their parental tumors for lengthy culture periods. NSCLC cell lines appear very representative of the lung cancer tumor from
which they were derived and thus provide suitable model systems for biomedical studies of this important neoplasm.
Lung cancers express lower levels of prostacyclin than normal lung tissues. Prostacyclin prevents lung cancer in a variety of mouse models. A randomized phase II trial comparing oral iloprost (a ...prostacyclin analog) with placebo in high-risk subjects showed improvement in bronchial histology in former, but not current, smokers. This placebo-controlled study offered the opportunity for investigation of other potential intermediate endpoint and predictive biomarkers to incorporate into chemoprevention trials. Matched bronchial biopsies were obtained at baseline and at 6-month follow-up from 125 high-risk individuals who completed the trial: 31/29 and 37/28 current/former smokers in the iloprost and placebo arm, respectively. We analyzed the expression of 14 selected miRNAs by Real Time PCR in 496 biopsies. The expression of seven miRNAs was significantly correlated with histology at baseline. The expression of miR-34c was inversely correlated with histology at baseline (P < 0.0001) and with change in histology at follow-up (P = 0.0003), independent of treatment or smoking status. Several miRNAs were also found to be differentially expressed in current smokers as compared with former smokers. In current smokers, miR-375 was upregulated at baseline (P < 0.0001) and downregulated after treatment with iloprost (P = 0.0023). No miRNA at baseline reliably predicted a response to iloprost. No biomarker predictive of response to iloprost was found. MiR-34c was inversely correlated with baseline histology and with histology changes. Mir-34c changes at follow-up could be used as a quantitative biomarker that parallels histologic response in formalin-fixed bronchial biopsies in future lung cancer chemoprevention studies.
The tumor suppressor gene RASSF1A regulates cell cycle progression, apoptosis, and microtubule stability and is inactivated by promoter methylation in approximately 50% of breast cancers. It has been ...shown previously that the polymorphism A133S in RASSF1A reduces its ability to regulate cell cycle progression and this polymorphism is associated with an increased risk of breast cancer. We analyzed the frequency of RASSF1A A133S in 190 Caucasian women without breast cancer and 653 patients with breast cancer including 138 BRCA1 and BRCA2 (BRCA1/2) mutation carriers, 395 non-BRCA1/2 mutations carriers, and 120 untested for BRCA1/2 mutations. Patients with breast cancer had a higher frequency of A133S than the controls P = 0.017; odds ratios (OR), 1.71; 95% confidence intervals (95% CI), 1.10-2.66. There is also a higher frequency of A133S in patients with higher familial breast cancer risk (P = 0.029; OR, 1.76; 95% CI, 1.06-2.92) and patients carrying BRCA1/2 mutations (P = 0.037, OR, 1.82; 95% CI, 1.04-3.18). Importantly, we found that the co-occurrence of a BRCA1 or BRCA2 mutation and A133S in RASSF1A was associated with earlier onset of breast cancer compared with those individuals with either a BRCA1/2 mutation or the A133S polymorphism alone (36.0 versus 42.0 years old, P = 0.002). Our data suggest that the presence of the RASSF1A A133S polymorphism is associated with breast cancer pathogenesis in general and modifies breast cancer age of onset in BRCA1/2 mutations carriers. Our results warrant a large-scale study to examine the effect of the A133S polymorphism in the development of breast and other types of cancers.
The treatment of advanced prostate cancer has been transformed by novel antiandrogen therapies such as enzalutamide. Here, we identify induction of glucocorticoid receptor (GR) expression as a common ...feature of drug-resistant tumors in a credentialed preclinical model, a finding also confirmed in patient samples. GR substituted for the androgen receptor (AR) to activate a similar but distinguishable set of target genes and was necessary for maintenance of the resistant phenotype. The GR agonist dexamethasone was sufficient to confer enzalutamide resistance, whereas a GR antagonist restored sensitivity. Acute AR inhibition resulted in GR upregulation in a subset of prostate cancer cells due to relief of AR-mediated feedback repression of GR expression. These findings establish a mechanism of escape from AR blockade through expansion of cells primed to drive AR target genes via an alternative nuclear receptor upon drug exposure.
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•GR induction is a common feature of enzalutamide-resistant prostate cancer•GR expression and activity promote resistance to enzalutamide•GR binds and regulates a subset of AR targets in a enzalutamide-insensitive manner•AR inhibition induces high levels of GR in primed prostate cells
Prostate cancer cells that have become resistant to androgen receptor (AR) antagonists escape the AR blockade by turning on expression of the closely related glucocorticoid receptor, which functionally substitutes for AR to drive growth, thus identifying GR as a potential therapeutic target.
TPS8596
Background: Comprehensive genomic profiling (CGP) has transformed the care of patients with advanced non-small cell lung cancer (NSCLC), giving many patients access to precision targeted ...treatment and immunotherapy with remarkable improvements in outcomes. Studies show that patients with lung cancers with oncogenic drivers are the least likely group to benefit from checkpoint inhibitors and are better served by enrollment in studies of targeted therapies. Early-stage NSCLC is now poised to benefit from these precision approaches with the regulatory approval of the first tyrosine kinase inhibitors and checkpoint inhibitors for the adjuvant treatment of resected NSCLC, each requiring testing for precision biomarkers. Neoadjuvant precision therapy for NSCLC has the potential to further improve treatment outcomes. Methods: The LCMC4 Evaluation of Actionable Drivers in EaRly Stage Lung Cancer (LEADER) Neoadjuvant Screening Trial (NCT04712877) is a collaborative diagnostic study developed by the Lung Cancer Mutation Consortium (LCMC), supported by the Thoracic Surgery Oncology Group and the Lung Cancer Research Foundation. The primary objective is to determine the proportion of patients with stage IA2-III lung cancers who possess actionable oncogenic drivers, defined as 1 of 11 actionable genomic alterations: mutations in EGFR, BRAF
V600E
, MET exon 14, KRAS G12C, and HER2, rearrangements in ALK, RET, NTRK, and ROS1, and amplification of MET and HER2. The study will also assess the feasibility of CGP to detect actionable oncogenic drivers in patients with suspected early-stage lung cancers scheduled to undergo biopsies to establish the diagnosis of lung cancer. The protocol will enroll 1000 patients with operable stage IA2-III (TNM 8th edition) lung cancer who will undergo CGP utilizing the Foundation Medicine 324 gene assay as well as paired liquid biopsy analysis. Results will enable selection of neoadjuvant therapy and enrollment onto independent therapeutic trials with genomically matched neoadjuvant treatment, standard therapies, or other trials if no driver is detected. The approach will be considered feasible if >35% of non-squamous NSCLCs have 1 of the 11 actionable alterations. Tumor mutational burden and PD-L1 IHC will be assessed. Plasma specimens collected pre- and post neoadjuvant treatment and post-surgery will be used for research to study the ability of circulating tumor DNA to assess neoadjuvant treatment response and minimal residual disease. 26 academic sites in the US plan to enroll patients. Clinical trial information: NCT04712877.
The discovery of frequent 8p11-p12 amplifications in squamous cell lung cancer (SQLC) has fueled hopes that FGFR1, located inside this amplicon, might be a therapeutic target. In a clinical trial, ...only 11% of patients with 8p11 amplification (detected by FISH) responded to FGFR kinase inhibitor treatment. To understand the mechanism of FGFR1 dependency, we performed deep genomic characterization of 52 SQLCs with 8p11-p12 amplification, including 10 tumors obtained from patients who had been treated with FGFR inhibitors. We discovered somatically altered variants of FGFR1 with deletion of exons 1-8 that resulted from intragenic tail-to-tail rearrangements. These ectodomain-deficient FGFR1 variants (ΔEC-FGFR1) were expressed in the affected tumors and were tumorigenic in both in vitro and in vivo models of lung cancer. Mechanistically, breakage-fusion-bridges were the source of 8p11-p12 amplification, resulting from frequent head-to-head and tail-to-tail rearrangements. Generally, tail-to-tail rearrangements within or in close proximity upstream of FGFR1 were associated with FGFR1 dependency. Thus, the genomic events shaping the architecture of the 8p11-p12 amplicon provide a mechanistic explanation for the emergence of FGFR1-driven SQLC. Specifically, we believe that FGFR1 ectodomain-deficient and FGFR1-centered amplifications caused by tail-to-tail rearrangements are a novel somatic genomic event that might be predictive of therapeutically relevant FGFR1 dependency.
Lineage plasticity has long been documented in both small cell lung cancer (SCLC) and neuroblastoma, two clinically distinct neuroendocrine (NE) cancers. In this study, we quantified the NE features ...of cancer as NE scores and performed a systematic comparison of SCLC and neuroblastoma. We found neuroblastoma and SCLC cell lines have highly similar molecular profiles and shared therapeutic sensitivity. In addition, NE heterogeneity was observed at both the inter- and intra-cell line levels. Surprisingly, we did not find a significant association between NE scores and overall survival in SCLC or neuroblastoma. We described many shared and unique NE score-associated features between SCLC and neuroblastoma, including dysregulation of Myc oncogenes, alterations in protein expression, metabolism, drug resistance, and selective gene dependencies.
Our work establishes a reference for molecular changes and vulnerabilities associated with NE to non-NE transdifferentiation through mutual validation of SCLC and neuroblastoma samples.
Krabbe disease is an infantile neurodegenerative disorder resulting from pathogenic variants in the GALC gene that causes accumulation of the toxic sphingolipid psychosine. GALC variants are also ...associated with Lewy body diseases, an umbrella term for age-associated neurodegenerative diseases in which the protein α-synuclein aggregates into Lewy bodies. To explore whether α-synuclein in Krabbe disease has pathological similarities to that in Lewy body disease, we performed an observational post-mortem study of Krabbe disease brain tissue (n = 4) compared to infant controls (n = 4) and identified widespread accumulations of α-synuclein. To determine whether α-synuclein in Krabbe disease brain displayed disease-associated pathogenic properties we evaluated its seeding capacity using the real-time quaking-induced conversion assay in two cases for which frozen tissue was available and strikingly identified aggregation into fibrils similar to those observed in Lewy body disease, confirming the prion-like capacity of Krabbe disease-derived α-synuclein. These observations constitute the first report of prion-like α-synuclein in the brain tissue of infants and challenge the putative view that α-synuclein pathology is merely an age-associated phenomenon, instead suggesting it results from alterations to biological pathways, such as sphingolipid metabolism. Our findings have important implications for understanding the mechanisms underlying Lewy body formation in Lewy body disease.
Using immunoblotting techniques we studied the sera from small cell lung cancer and non-small cell lung cancer patients for antibodies directed against p53. We have also characterized the majority of ...these patients' tumors for p53 mutations. In the sera of 13% of the patients (4 of 40 small cell lung cancer and 2 of 6 non-small cell lung cancer) we found antibodies specific for the p53 tumor suppressor gene product. All of the antibody-positive patients tested had p53 missense mutations and expressed detectable p53 antigen in their tumor cell lines. No anti-p53 antibodies were detected in sera from patients whose tumor had p53 stop, splice/stop, splice, or frameshift mutations (n = 10). Thus, while we find that the ability of lung cancer patients to develop anti-p53 antibodies is correlated with the type of p53 mutation, many patients have tumors with missense p53 mutations and did not develop anti-p53 antibodies. The presence of p53 antibodies was not correlated to stage, prior treatment, sex, or survival. None of these lung cancer patient sera had measurable amounts of p53 antigen. By immunoblotting all six anti-p53 antisera we were able to detect a variety of mutant p53 proteins (including those from antibody-negative patients) and detected wild-type p53 protein. The development of anti-p53 antibodies represents an interesting model system for studying immune responses in cancer patients against mutant oncogene products.
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