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Sequence requirements for micro RNA processing and function in human cells.

Most eukaryotes encode a substantial number of small noncoding RNAs termed micro RNAs (miRNAs). Previously, we have demonstrated that miR-30, a 22-nucleotide human miRNA, can be processed from a longer transcript bearing the proposed miR-30 stem-loop precursor and can translationally inhibit an mRNA-bearing artificial target sites. We also demonstrated that the miR-30 precursor stem can be substituted with a heterologous stem, which can be processed to yield novel miRNAs and can block the expression of endogenous mRNAs. Here, we show that a second human miRNA, termed miR-21, can also be effectively expressed when its precursor forms part of a longer mRNA. For both miR-30 and miR-21, mature miRNA production was highly dependent on the integrity of the precursor RNA stem, although the underlying sequence had little effect. In contrast, the sequence of the terminal loop affected miRNA production only moderately. Processing of the initial, miR-30-containing transcript led to the production of not only mature miR-30 but also to the largely nuclear excision of an approximately 65-nucleotide RNA that is likely to represent an important intermediate in miR-30 processing. Consistent with this hypothesis, mutations that affected mature miR-30 production inhibited expression of this miR-30 pre-miRNA to an equivalent degree. Although point mutations could block the ability of both miR-30 and miR-21 to inhibit the translation of mRNAs bearing multiple artificial miRNA target sites, single point mutations only attenuated the miRNA-mediated inhibition of genes bearing single, fully complementary targets. These results suggest that miRNAs, and the closely similar small interfering RNAs, cannot totally discriminate between RNA targets differing by a single nucleotide.

Base Sequence↗

Comparative analysis of mouse NotI linking clones with mouse and human genomic sequences and transcripts.

NotI cleavage sites are frequently associated with CpG islands that identify the 5' regulatory sites of functional genes in the genome. Therefore we analyzed a sample of 22 NotI linking clones prepared from mouse brain DNA, to determine whether these mouse NotI site associated clones could be used for comparative analysis of mouse and human genomes by cross-reaction with both mouse and human genomic DNA and RNA in Southern and Northern hybridization. We further examined whether we could establish the identity of these clones with known genes by comparing the nucleotide sequences surrounding the NotI site with the GenBank database. We observed that 70% of the clones cross-hybridized with human DNA and that 4 of 11 tested clones (36%) detected a transcript in human HeLa cells RNA whereas 73% clones (8/11) detected transcripts in mouse RNAs from one or more organs. Single pass sequence analysis was successful on 16 of 19 clones. The GC content in these sequence was very high (48.8% to 73.8%) suggesting that 12 of 16 sequenced clones contained a CpG island. Three out of 19 clones showed significant similarity with previously analyzed mouse gene sequences in GenBank, including the mouse rRNA gene family, cathepsin and the scip POU-domain genes. In addition, two sequences showed significant similarity to the human and rabbit protein phosphatase 2A-beta subunit and the human transforming growth factor-beta. Thus, 5 of 16 clones showed homology with identified genes. These results and the recent work of using RLGS methods for genetic mapping indicate that NotI linking clones can be used to efficiently cross reference a comparative analysis of the mouse and human genomic maps.

Animals↗

Mapping of RNA polymerase on mammalian genes in cells and nuclei.

The assembly of an RNA polymerase II initiation complex at a promoter is associated with the melting of the DNA template to allow the polymerase to read the DNA sequence and synthesize the corresponding RNA. Using the specific single-stranded modifying reagent KMnO4 and a new genomic sequencing technique, we have explored the melted regions of specific genes in genomic DNA of whole cells or of isolated nuclei. We have demonstrated for the first time in vivo the melting in the promoter proximal transcribed region that is associated with the presence of RNA polymerase II complexes. An interferon-inducible gene, ISG-54, exhibited KMnO4 sensitivity over approximately 300 nucleotides downstream of the RNA initiation site in interferon-treated cells when the gene was actively transcribed but not in untreated cells where the gene was not transcribed. The extent of KMnO4 modification was proportional to transcription levels. The KMnO4 sensitivity was retained when nuclei were isolated from induced cells but was lost if the engaged polymerases were further allowed to elongate the nascent RNA chains ("run-on"). The sensitivity to KMnO4 in isolated nuclei was retained if the run-on incubation was performed in the presence of alpha-amanitin, which blocks progress of engaged polymerases. A similar analysis identified an open sequence of only approximately 30 bases just downstream of the start site of the transthyretin (TTR) gene in nuclei isolated from mouse liver, a tissue where TTR is actively transcribed. This abrupt boundary of KMnO4 sensitivity, which was removed completely by allowing engaged polymerases to elongate RNA chains, suggests that most polymerases transcribing this gene paused at about position +20. The possibility of mapping at the nucleotide level the position of actively transcribing RNA polymerases in whole cells or isolated nuclei opens new prospects in the study of transcription initiation and elongation.

Animals↗

Wound healing in Atlantic spiny dogfish sharks.

Field observations and limited experimental studies indicate that elasmobranchs can repair substantial skin injuries, but the temporal course and cellular composition of wound healing in Atlantic spiny dogfish remain poorly characterized. We conducted an exploratory laboratory study in 20 female Atlantic spiny dogfish (Squalus acanthias) using standardized full-thickness skin wounds monitored by serial photography for 35 days, histological analysis at defined post-injury time points, and pooled single-nucleus RNA sequencing of intact and wounded skin. A continuous neoepithelial layer covered all examined wound beds by Day 1, whereas macroscopic wound area decreased progressively over 35 days and dermal denticles remained absent from the repaired surface. Histological examination showed progressive neoepidermal maturation, basement-membrane reformation, collagen deposition, and granulation-tissue organization, indicating that epithelial coverage preceded restoration of normal skin architecture. Single-nucleus RNA sequencing identified epithelial, stromal, vascular, pigment, neural, and immune-cell populations. T and B cells were detected in intact skin, and their relative abundance, together with that of several other leukocyte populations, increased at Day 1 and generally declined by Day 14. Because samples were pooled by time point, these transcriptomic changes are descriptive. These findings characterize rapid early reepithelialization followed by slower tissue remodeling in Atlantic spiny dogfish and provide a foundation for future comparative studies of elasmobranch skin repair.

Animals↗

Dendritic cell susceptibility to hepatitis C virus genotype 1 infection.

In vitro infection of human monocyte-derived dendritic cells was carried out to study their susceptibility to hepatitis C virus (HCV) infection. Immature dendritic cells and mature dendritic cells were incubated overnight at 37 degrees C with HCV-positive (genotype 1) serum samples; the presence of the viral genome associated with the production of its replicative intermediate was used as evidence of infection. In immature dendritic cells, HCV RNA was detectable from days 1-10 post-infection (p.i.), and de novo synthesis of negative-strand HCV RNA could be demonstrated by a strand-specific rTth reverse transcription-polymerase chain reaction at day 2. In mature dendritic cells, the positive-strand form was detectable from days 1-5 p.i., while the negative-strand HCV RNA appeared at days 1 and 2 p.i. Quasispecies present in the inoculum and 6 days p.i. were analyzed by sequencing hypervariable region 1 of the E2 protein. Only two of seven HVR variants present in the inoculum were found in HCV-infected immature dendritic cells. Another two HVR variants not found in the inoculum were recovered from infected immature dendritic cells, suggesting serum minor variants selection or virus evolution during in vitro replication. Analysis by single-strand conformation polymorphism assay of 5' untranslated region of HCV sequences showed that the patterns obtained from the inoculum and infected immature dendritic cells and mature dendritic cells differed slightly. These findings indicate that both immature dendritic cells and mature dendritic cells are susceptible to HCV genotype 1 infection, supporting at least HCV RNA replication. This model should be a valuable tool for the study of modulation of dendritic cell functions in HCV infection.

Amino Acid Sequence↗

Polymerase chain reaction and in situ hybridization: applications in toxicological pathology.

Polymerase chain reaction (PCR) and in situ hybridization (ISH) have revolutionized the study of genes and gene expression, and many of these molecular biology advances will greatly impact research in toxicological pathology. PCR is one of the most powerful tools in molecular biology and involves primer-mediated enzymatic in vitro amplification of specific target DNA sequences. Recent innovative methods utilizing PCR technology have been developed to detect mutations in neoplastic and small subpopulations of cells, to study biomarkers of genetic susceptibility and genes involved with carcinogen metabolism, to estimate mutation frequencies, to find novel genes induced by chemical exposure, and to characterize gene expression. ISH provides data on individual cells rather than an average of total cellular populations and allows analysis for heterogeneity. When combined with PCR, the sensitivity of ISH is elevated, and single-copy DNA sequences, single-base mutations, or low copies of messenger RNA (mRNA) can potentially be detected within individual cells. Herein are reviewed ISH- and PCR-based techniques such as single-strand conformation polymorphism analysis to detect point mutations, allelotypic analysis for loss of heterozygosity, differential display of mRNA to characterize gene expression, quantitative reverse transcriptase polymerase chain reaction, and in situ polymerase chain reaction with emphasis on current or potential applications in toxicological pathology. These new and evolving techniques offer tremendous potential in providing new insights into the molecular basis of toxicity and carcinogenesis.

Animals↗

Application of optical trapping for cells grown on plates: optimization of PCR and fidelity of DNA sequencing of p53 gene from a single cell.

BACKGROUND: Optical trapping has traditionally been used to visually select and isolate nonadherent cells grown in suspension because cells grown in monolayers will rapidly reattach to surfaces if suspended in solution. We explored methods to slow cell reattachment that are also compatible with high-fidelity PCR. METHODS: Using HeLa cells grown on plates and suspended after trypsinization, we measured the efficiency of capture by retention and movement of the cell by the laser. Success for removing a captured cell by pipette was determined by PCR amplification of the 5S rRNA gene. After optimizing PCR amplification of a 2049-bp region of the p53 gene, we determined PCR fidelity by DNA sequencing. RESULTS: Addition of bovine serum albumin to suspended cells slowed reattachment from seconds to minutes and allowed efficient trapping. The success rate of removing a cell from the trap by pipette to a PCR tube was 91.5%. The 5S PCR assay also revealed that DNA and RNA that copurify with polymerases could give false-positive results. Sequence analysis of four clones derived from a single cell showed only three polymerase errors in 7200 bp of sequence read and revealed difficulties in reading the correct number in a run of 16 A:T. Comparison of the HeLa and wild-type human sequences revealed several previously unreported base differences and an (A:T)(n) length polymorphism in p53 introns. CONCLUSIONS: These results represent the first use of optical trapping on adherent cells and demonstrate the high accuracy of DNA sequencing that can be achieved from a single cell.

Cell Separation↗

Long RT-PCR of the entire 8.5-kb NF1 open reading frame and mutation detection on agarose gels.

Previous approaches to mutation detection in mRNA from the neurofibromatosis 1 (NF1) locus have required the PCR amplification of five or more overlapping cDNA segments to screen the entire 8.5-kb open reading frame (ORF). Systematically, these assays do not detect deletions that span the region of overlap (usually 1-3 exons) of any two consecutive target segments. In such cases, amplification from the mutant region of the disease-causing allele fails because binding sites for the PCR primers are missing, but amplification from the normal allele proceeds, yielding only the normal product. To alleviate this problem, we have developed a protocol to reverse transcribe and amplify the entire protein-coding sequence of NF1 as a single PCR product, starting with total RNA from lymphoblast cell lines or from whole blood. The 8.7-kb RT-PCR product was prepared from nine NF1 patients with known deletions or insertions, ranging in size from a 30-bp deletion within 1 exon to a 2.4-kb deletion that removes 12 exons. Agarose gel analysis of the initial products detected deletions as small as 341 bp. Restriction endonuclease digestion with Asel and Fspl, followed by agarose gel electrophoresis, revealed the predicted abnormal bands in all nine patients. All mutant bands were identified readily by observers with no knowledge of the patients' mutations. This simple assay should detect a great variety of insertion/deletion mutations in the NF1mRNA internal to the primer binding sites, including all possible single and multiple exon dropouts and approximately 30% of all previously reported NF1 mutations.

Base Sequence↗

Hypersensitivity of DNA in transcriptionally active chromatin to ionizing radiation.

We have examined the size distribution of single-strand fragments of total 3H-labeled DNA and of DNA sequences complementary to specific probes in gamma-irradiated and unirradiated mouse L929 cells. Those DNA sequences which hybridize to rDNA or to poly(A+)RNA have lower number average molecular weights and sustain 5--6-times the number of single-strand breaks as do satellite DNA sequences or the bulk DNA. We therefore conclude that transcriptionally active DNA sequences are more susceptible to ionizing radiation-induced damage than are inactive sequences, and suggest that these differential susceptibilities are a likely consequence of differences in their chromatin organization.

Animals↗

Single-cell transcriptomic atlas of Alzheimer's disease middle temporal gyrus reveals region, cell type, and sex specificity of gene expression with novel genetic risk for MERTK in female.

BackgroundAlzheimer's disease (AD), the most common age-related neurodegenerative disease, is closely associated with both amyloid-β plaque and neuroinflammation. Two thirds of AD patients are female, and they have a higher disease risk; women with AD have more extensive brain histological changes than men along with more severe cognitive symptoms and neurodegeneration.ObjectiveThis study aimed to determine how sex difference induces structural brain changes and molecular cell vulnerabilities in AD, with a focus on identifying sex-specific transcriptional alterations and genetic risk factors.MethodsWe performed single nucleus RNA sequencing on postmortem brains from individuals with AD and age- and sex-matched controls, focusing on the middle temporal gyrus, a cortical brain region strongly affected by the disease, and integrated single nucleus RNA sequencing results with genome-wide association study (GWAS) data using cell type-specific enrichment and generalized gene-set analysis approaches. The analysis pipeline is provided with threshold information.ResultsWe identified a selectively vulnerable subpopulation of layer 2/3 excitatory neurons that were RORB-negative and CDH9-expressing in both males and females. Disease-associated, but sex-independent, reactive astrocyte signatures were also present. In clear contrast, the microglia signatures of AD brains differed between males and females. Integrating single cell transcriptomic data with results from GWAS, we identified MERTK genetic variation as a candidate novel risk factor for AD selectively in females.ConclusionsTaken together, our single cell atlas of middle temporal gyrus revealed a unique cellular-level view of sex-specific transcriptional changes in AD, illuminating GWAS identification of sex-specific AD genes. These data serve as a rich resource for interrogation of the molecular and cellular basis of AD.

Alzheimer's disease↗

Cell-type-specific defense priming and NHP-dependent systemic immunity against Pectobacterium in Chinese cabbage.

Defense priming is an effective strategy for mounting the defensive capacity of plants. Primed plants undergo minimal changes, enabling rapid, robust responses to subsequent pathogen attack. The cell-type-specific mechanisms underlying priming and systemic immunity remain unclear. Using single-nucleus RNA sequencing (snRNA-seq), we reveal how primed Chinese cabbage coordinates N-hydroxypipecolic acid (NHP)-dependent systemic immunity against Pectobacterium carotovorum. NHP accumulates as a phloem-mobile priming signal. snRNA-seq identified a priming-specific epidermal cell state transition and transcriptional cascade: BrWRKY18-1 activates BrWRKY33-1 expression during priming, initiating NHP-dependent systemic immunity. At post-challenge primed state, pathogenesis-related genes (PRs), such as BrPR3, BrPR4-1, and BrPR4-2, are predominantly expressed in systemic tissues to inhibit infection. Notably, the functionality of these PR genes in immunity necessitates their expression in all cells to effectively enhance defensive resistance. This NHP-transcription factor-PR axis couples mobile signaling to systemic immunity, elucidating cell-type-specific defense priming.

Plant Immunity↗

Antiviral activity of RNA molecules containing self-releasing ribozymes targeted to lymphocytic choriomeningitis virus.

Ribozymes catalytically cleave substrate RNA molecules in a sequence-specific manner. Engineered ribozymes can be developed and introduced into tissue culture cells to regulate gene expression and to inhibit viral replication. We have previously reported on the construction of cell lines that constitutively express a single antiviral ribozyme embedded in a lengthy RNA transcript. These cells exhibited a marked reduction in their ability to support viral infection. Here we report the construction of RNA molecules that contain one or two antiviral ribozymes, each specific for a different cleavage site on the genome of the target virus, lymphocytic choriomeningitis virus (LCMV), and each contained in a self-cleavage cassette comprising cis-acting ribozymes designed to release the antiviral molecules from the transcript. In vitro studies showed that both antiviral ribozymes were released properly from the RNAs following cleavage by the flanking ribozymes and that these released ribozymes functioned as expected in cleaving the target virus RNA. These self-cleaving cassettes have been clones into a retroviral vector downstream of, but in the same transcript as, the chloramphenicol acetyltransferase (CAT) gene. Thus, we hoped to employ CAT as a surrogate marker of ribozyme transcription. Stably transformed cell lines were established. Cleavage by the cis-acting ribozymes was incomplete, as assessed by Northern blot analysis and by the ability of transformed cells to produce infectious retroviral particles. Nevertheless, the antiviral ribozyme sequences exerted effects in tissue culture. LCMV RNA levels in ribozyme-expressing cells were suppressed, and infectious virus yields were decreased by up to 95% compared with normal cells and with cells expressing inverted ribozymes. The antiviral effects correlated with CAT levels, but there was no significant difference between cell lines expressing a single ribozymes and those expressing two.

3T3 Cells↗

Genetic structure and transforming sequence of avian sarcoma virus UR2.

We have recently shown that a newly isolated avian sarcoma virus, UR2, is defective in replication and contains no sequences homologous to the src gene of Rous sarcoma virus. In this study, we analyzed the genetic structure and transforming sequence of UR2 by oligonucleotide fingerprinting. The sizes of the genomic RNAs of UR2 and its associated helper virus, UR2AV, were determined to be 24S and 35S, respectively, by sucrose gradient sedimentation. The molecular weight of the 24S UR2 genomic RNA was estimated to be 1.1 x 10(6), corresponding to 3,300 nucleotides, by gel electrophoresis under the native and denatured conditions. RNase T1 oligonucleotide mapping indicated that UR2 RNA contains seven unique oligonucleotides in the middle of the genome and shares eight 5'- and six 3'-terminal oligonucleotides with UR2AV RNA. From these data, we estimated that UR2 RNA contains a unique sequence of about 12 kilobases in the middle of the genome, and contains 1.4 and 0.7 kilobases of sequences shared with UR2AV RNA at the 5' and 3' ends, respectively. Partial sequence analysis of the UR2-specific oligonucleotides by RNase A digestion revealed that there are no homologous counterparts to these oligonucleotides in the RNAs of other avian sarcoma and acute leukemia viruses studied to date. UR2-transformed non-virus-producing cells contain a single 24S viral RNA which is most likely the message coding for the transforming protein of UR2. On the basis of the uniqueness of the transforming sequence, we concluded that UR2 is a new member of the defective avian sarcoma viruses.

Alpharetrovirus↗

Monocarboxylate Transporter 2 (MCT2) Reduction Is Associated with Increased Lung Tumor Growth and Alterations in the Immune Microenvironment in a Subcutaneous Tumor Model.

Monocarboxylate transporter 2 (MCT2; SLC16A7) is a high-affinity pyruvate transporter implicated in cancer metabolism. However, its role in lung cancer progression and the tumor microenvironment remains unclear. This study examined the effects of MCT2 reduction on tumor growth and cell-type-specific transcriptional changes within the tumor microenvironment. MCT2 loxP/loxP mice were crossed with mCre-Tg mice, and MCT2 deletion was induced by tamoxifen. Control (CO) mice received vehicle treatment. TC1 cells (100,000 cells/mouse) were injected subcutaneously, and tumors were harvested after 24 days. Single-nucleus RNA sequencing (snRNA-seq) was performed on isolated tumor nuclei (4000 nuclei/sample; n = 3 per group) using the 10x Genomics Chromium platform. Data were processed with Cell Ranger v3.0.2 and Seurat v5.2.1, followed by differential expression and pathway enrichment analyses integrated with macrophage bulk RNA-seq data. Tumors in mice with systemic MCT2 reduction grew significantly faster than those in control mice, demonstrating an association between host MCT2 reduction and increased tumor growth. Transcriptomic analysis generated high-quality profiles from 6864 CO and 10,055 KO nuclei. Clustering identified 12 cellular populations and cell types. MCT2 reduction altered pathways involved in glycolysis, the tricarboxylic acid cycle, oxidative phosphorylation, and fatty acid metabolism across multiple populations. Macrophages showed prominent transcriptional changes, including enrichment of MAPK, PI3K-Akt, IgSF-CAM, ECM, and cytokine-cytokine signaling pathways. These findings were supported by macrophage bulk RNA-seq data. Systemic MCT2 reduction was associated with increased tumor growth and broad transcriptional alterations within the tumor micro-environment. Differences in metabolic and immune-related transcriptional programs, particularly in macrophages, identify potential mechanisms associated with tumor progression that warrant further functional investigation.

Animals↗

From wild to domestic: Single-cell transcriptomic perspectives on hippocampal regulation and evolution.

How domestication shapes brain evolution remains an open question. In this study, we integrated single-nucleus RNA sequencing (snRNA-seq), population genomics, and machine learning to investigate the hippocampal evolution under domestication. Across-species comparisons revealed that hippocampal cell type profiles are largely conserved across vertebrate species, while supporting the presence of adult hippocampal neurogenesis in birds. We further found that domestication and selective breeding likely influence the cellular composition and molecular regulation of the hippocampus. Our findings provide cellular evidence supporting the hypothesis that domestication affects adult hippocampal neurogenesis. Additionally, we showed that genes associated with neural progenitor cells (NPC) states and cell-marker programs are enriched for signatures of selection. Many of these genes function as regulators of neurogenesis and pathways mediating stress and fear reduction. Specifically, we identified selection at the FKBP5 promoter that may influence its expression in the NPC lineage, potentially contributing to stress-response regulation during domestication. Collectively, these results suggest that domestication is associated with hippocampal remodeling as part of an adaptive response to human-managed environments. This study provides a cellular and genetic perspective on how domestication reshapes the brain and offers a basis for further investigation into the mechanisms of neural evolution within the context of microevolution.

Animals↗

A single-nucleus transcriptome atlas of soybean anthers.

Anther development is crucial for plant sexual reproduction. However, a high-resolution, cell-type-specific transcriptomic atlas of this process is lacking for the legume crop soybean (Glycine max). Here, we construct a comprehensive transcriptional atlas of developing soybean anthers using single-nucleus RNA sequencing (snRNA-seq). We identify and characterize nine distinct cell types spanning both somatic and reproductive lineages. Our analysis reveals robust transcriptional continuity across anther developmental stages and dynamic reprogramming during key transitions. Notably, the shift from diploid meiocytes to haploid unicellular microspores is marked by the induction of previously inactive genes, despite an overall reduction in transcript abundance. Subsequently, within bicellular microspores, generative and vegetative cell lineages exhibit sharply divergent transcriptional programs: generative cells specialize in mRNA export and turnover, whereas vegetative cells up-regulate translational machinery. Evolutionary analysis further indicates that generative-cell-specific genes are subject to more relaxed purifying selection compared to those specific to vegetative cells. Functional validation using mutants generated by CRISPR/Cas9-mediated genome editing and EMS mutagenesis reveals the essential roles of OSD1A and PKSA in pollen development and fertility. This high-resolution atlas provides fundamental insights into the transcriptional regulation of soybean anther development and serves as a valuable resource for manipulating male fertility to advance hybrid breeding programs. The data are available at https://databases.genedenovo.com/pollen.

Glycine max↗

Single-nucleus profiling reveals a core disease signature and cell type-specific vulnerabilities in early Rett syndrome.

Rett syndrome (RTT) is an X-linked neurological disorder caused by MECP2 mutations, creating distinct cellular environments in females (mosaic) versus males (nonmosaic). Despite female patients representing most cases, how mosaicism contributes molecularly to RTT pathogenesis, particularly in presymptomatic stages, remains poorly understood. To address this question, we profiled hippocampal transcriptomes of young female and male RTT mice using bulk and single-nucleus RNA sequencing. We identified a core disease signature of consistently dysregulated genes only in MeCP2- cells across RTT models. Moreover, we uncovered non-cell autonomous effects exclusively in female MeCP2+ excitatory neurons, suggesting that these circuits are more vulnerable early in the mosaic RTT environment. The single-nuclei data also revealed an underappreciated MeCP2- interneuron subtype that had the most transcriptional dysregulation in both male and female RTT hippocampi. Together, these data highlight the different effects of MeCP2 loss on excitatory and inhibitory circuits between the mosaic and nonmosaic environments in early RTT pathogenesis.

Rett Syndrome↗

GPI-anchored molecule-like protein (GML) expression in non-small cell lung cancer (NSCLC).

BACKGROUND: GPI-anchored molecule-like protein (GML) has been identified as a new target molecule of p53. In esophageal cancer cell lines, expression of GML mRNA, which was found to be significantly correlated with in vitro anti-cancer drug sensitivity, was observed only in the presence of wild-type p53. MATERIALS AND METHODS: The relationship between expression of GML mRNA and p53 gene status in 24 non-small cell lung cancer (NSCLC) cell lines was examined using RT-PCR and PCR-SSCP followed by direct DNA sequencing. RESULTS: Expression of GML mRNA was observed in only 3 of 24 cell lines. In contrast to previous studies showing p53-dependent GML expression, of the 3 cell lines expressing GML mRNA, one had a p53 gene mutation (codon 245: Gly to Cys). CONCLUSION: These findings suggest that the expression of GML mRNA is infrequent and regulated in a p53-independent manner in NSCLC.

Carcinoma, Non-Small-Cell Lung↗