Loss of Heterozygosity in DNA Mismatch Repair Genes in Human Atherosclerotic Plaques

To detect the incidence of loss of heterozygosity (LOH) in DNA mismatch repair genes (MMR) occurring in atherosclerosis, fifty human autopsy cases of atherosclerosis were examined for LOH using 19 microsatellite markers, in three single and four tetraplex microsatellite assays. The markers used are located on or close to MMR genes. Fourteen specimens (28%) showed allelic imbalance in at least one locus. Loci hMSH2 (2p22.3–p16.1), hPMS1 (2q24.1–q32.1), and hMLH1 (3p21.32–p21.1) exhibited LOH (10, 10, and 12% respectively). We found that loss of heterozygosity on hMSH2, hPMS1, and hMLH1, occurs in atherosclerosis. The occurrence of such genomic alterations may represent important events in the development of atherosclerosis.     

Genomic instability on hMSH2, hMLH1, CD48 and IRF4 loci in pulmonary sarcoidosis

Pulmonary sarcoidosis shares certain features with immune disease and neoplasia, and microsatellite DNA alterations are detectable in sputum specimens of pulmonary sarcoidosis patients. The biological basis and significance of these findings remain obscure, while information regarding the genetic basis of the disease is limited. Using multiplex PCR-based microsatellite analysis, we investigated 40 markers located on 1p, 1q, 2p, 2q, 3p, 5q, 6p, 7p, 9p, 11q, 14q and 17p in 38 sputum specimens of pulmonary sarcoidosis patients. Loss of heterozygosity (LOH) was found in 13 of 38 (34.2%) patients in at least one locus. These alterations occurred in the subset of markers located in or close to DNA mismatch repair (MMR) genes, hMSH2 (2p22.3-p16.1) and hMLH1 (3p2l.32-p21.1), as well as in CD48 (1q21-q23) and IRF4 (6p23-p25), genes associated with lymphocyte activation. Microsatellite instability (MIN) was observed in five cases (13.2%) in at least one locus. Our data suggest that genomic instability in pulmonary sarcoidosis could be due to MMR defects, while alterations of lymphocyte-specific agents could account for granuloma formation.     

Loss of heterozygosity on chromosomes 1, 2, 8, 9 and 17 in cerebral atherosclerotic plaques

OBJECTIVE: Atherosclerosis is a fibroproliferative disease which has been attributed to several factors including genetic and molecular alterations. Initial studies have shown genetic alterations at the microsatellite level in the DNA of atherosclerotic plaques. Extending our initial findings, we performed a microsatellite analysis on cerebral atherosclerotic plaques. METHODS: Twenty-seven cerebral atherosclerotic plaques were assessed for loss of heterozygosity (LOH) and microsatellite instability (MI) using 25 microsatellite markers located on chromosomes 2, 8, 9 and 17. DNA was extracted from the vessels as well as the respective blood from each patient and subjected to polymerase chain reaction. RESULTS: Our analyses revealed that specific loci on chromosomes 2, 8, 9 and 17 exhibited a significant incidence of LOH. Forty-six percent of the specimens showed loss of heterozygosity at 2p13-p21, 48% exhibited LOH at 8p12-q11.2, while allelic imbalance was detected in 47% of the cases. The LOH incidence was 39%, 31% and 27% at 17q21, 9q31-34 and 17p13, respectively. Genetic alterations were detected at a higher rate as compared to the corresponding alterations observed in plaques from other vessels. DISCUSSION: This is the first microsatellite analysis using atherosclerotic plaques obtained from cerebral vessels. Our results indicate an elevated mutational rate on specific chromosomal loci, suggesting a potential implication of these regions in atherogenesis.     

Cannabinoid CB1 receptor inhibition decreases vascular smooth muscle migration and proliferation

Vascular smooth muscle proliferation and migration triggered by inflammatory stimuli and chemoattractants such as platelet-derived growth factor (PDGF) are key events in the development and progression of atherosclerosis and restenosis. Cannabinoids may modulate cell proliferation and migration in various cell types through cannabinoid receptors. Here we investigated the effects of CB₁ receptor antagonist rimonabant (SR141716A), which has recently been shown to have anti-atherosclerotic effects both in mice and humans, on PDGF-induced proliferation, migration, and signal transduction of human coronary artery smooth muscle cells (HCASMCs). PDGF induced Ras and ERK 1/2 activation, while increasing proliferation and migration of HCASMCs, which were dose dependently attenuated by CB₁ antagonist, rimonabant. These findings suggest that in addition to improving plasma lipid alterations and decreasing inflammatory cell migration and inflammatory response, CB₁ antagonists may exert beneficial effects in atherosclerosis and restenosis by decreasing vascular smooth muscle proliferation and migration.     

MYCL1, FHIT,SPARC, p16(INK4) and TP53 genes associated to lung cancer in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a specific form of chronic interstitial pneumonia limited to the lung and characterized by a fibroproliferative response with only minor signs of inflammation, which almost always causes rapid fibrotic destruction of the lung. In this study, we investigated genomic instability in IPF, using microsatellite DNA analysis, aiming to detect any specific genetic alterations for this disease. We used 40 highly polymorphic microsatellite DNA markers, in multiplex PCR assays, to examine 52 sputum specimens from IPF patients versus correspondent venous blood. Loss of heterozygosity (LOH) was found in 20 (38.5%) patients in at least one locus. These alterations were found on markers previously associated with lung cancer located on 1p34.3, 3p21.32-p21.1, 5q32-q33.1, 9p21 and 17p13.1 where MYCL1, FHIT, SPARC, p^16Ink4 and TP53 genes have been mapped respectively. These data provide new insights into IPF pathogenesis and a new perspective for its correlation with lung cancer.     

Monocyte chemoattractant protein-1 mediates angiotensin II-induced vascular smooth muscle cell proliferation via SAPK/JNK and ERK1/2

Abnormal vascular smooth muscle cells proliferation is the pathophysiological basis of cardiovascular diseases, such as hypertension, atherosclerosis, and restenosis after angioplasty. Angiotensin II can induce abnormal proliferation of vascular smooth muscle cells, but the molecular mechanisms of this process remain unclear. Here, we explored the role and molecular mechanism of monocyte chemotactic protein-1, which mediated angiotensin II-induced proliferation of rat aortic smooth muscle cells. 1,000 nM angiotensin II could stimulate rat aortic smooth muscle cells' proliferation by angiotensin II type 1 receptor (AT(1)R). Simultaneously, angiotensin II increased monocyte chemotactic protein-1 expression and secretion in a dose-and time-dependent manner through activation of its receptor AT(1)R. Then, monocyte chemotactic protein-1 contributed to angiotensin II-induced cells proliferation by CCR2. Furthermore, we found that intracellular ERK and JNK signaling molecules were implicated in angiotensin II-stimulated monocyte chemotactic protein-1 expression and proliferation mediated by monocyte chemotactic protein-1. These results contribute to a better understanding effect on angiotensin II-induced proliferation of rat smooth muscle cells.     

Complex characteristics of the alterations of oncogenes HER-2/ERBB-2, HER-1/ERBB-1, HRAS-1, C-MYC and antioncogenes p53, RB1, as well as deletions of loci of chromosome 17 in colon carcinoma]

Abnormalities of some oncogenes, antioncogenes and losses of heterozygosity (LOH) of chromosome 11p, 17p, and 17q in colorectal carcinomas (CC) was studied. Amplification of ERBB-1/HER-1 oncogene was detected in 2 of 56 cases; ERBB-2/HER-2- in 4 of 62. There was a lack of evidence for C-MYC oncogene amplification (67 cases). LOH of chromosome 11p (HRAS-1 probe) was found in 2 of 37 informative (heterozygous) cases; such events were not accompanied by point mutations in "hot" codons (12th or 61st) in the remaining allele. Prevalence of A3 and A4 alleles of HRAS-1 oncogene (68 cases) as compared to healthy donors was noted. RB-1 (41 cases) and p53 (62 cases) suppressor genes did not show any alterations in Southern-blot analysis. LOH of chromosome 17p (YNZ-22 probe) was found in 15 of 26 heterozygous CC; 17q (THH-59 probe)--in 4 of 16. Analysis of 175th codon of p53 gene revealed only one case of mutation in 35 CC studied. Finally, we were able to detect genetic alterations in 23 of 40 (58%) CC, that were studied on each parameter using Southern-blot. We failed to find any correlation between various molecular abnormalities or clinical characteristics. The data obtained are in disagreement with the view concerning frequent involvement of p53 antioncogene in chromosome 17p deletions.     

3p21, 5q21, 9p21 and 17p13 allelic deletions accumulate in the dysplastic spectrum of laryngeal carcinogenesis and precede malignant transformation

A tissue field of somatic genetic alterations precede the histopathological phenotypic changes of carcinoma. Loss of Heterozygosity (LOH) at the sites of known or putative tumor suppressor genes is a common genetic abnormality detected in precancerous conditions. These genomic changes could be of potential use in the diagnosis and prognosis of pre-malignant laryngeal lesions. Recently the concept of laryngeal intraepithelial neoplasia (LIN) was introduced. To evaluate patients with an increased risk of developing invasive laryngeal carcinoma via a dysplasia-carcinoma progression we investigated 102 microdissected cell populations. Cell populations were procured from 15 laryngectomy specimens with different peritumoral histological changes adjacent to the squamous cell carcinoma cells and 15 laryngeal endoscopic biopsies with no evidence of malignant transformation in a 6-10-year follow-up period. Histological diagnoses were subdivided into keratosis without dysplasia (KWD), with mild dysplasia (LIN 1), with moderate dysplasia (LIN 2), and with severe dysplasia or carcinoma in situ (LIN 3). Microsatellite analysis was performed with the aim of studying LOH of 5q21 (APC), 9p21 (p16), 3p21 and 17p13 (p53) chromosomal regions. Frequent allelic losses were found in carcinoma cells at p53 (54%), p16 (66%), 3p21(87%) and 5q21(58%). Identical LOH patterns were determined in 100% of the LIN3 peritumoral cells, 60% of LIN2, 50% of LIN 1 and 25% of KWD. In contrast, histologically normal mucosae, KWD and LIN1 lesions without malignant progression showed no allelic loss. These results show that dysplasia correlates with LOH at 3p21, 5q21, 9p21 and 17p13 in early laryngeal carcinogenesis. These genomic changes in pre-malignant laryngeal lesions could be of potential use as markers for cancer risk assessment.     

Genome-wide detection of LOH in prostate cancer using human SNP microarray technology

Loss of heterozygosity (LOH) of chromosomal regions is crucial in tumor progression. In this study we assessed the potential of the Affymetrix GeneChip HuSNP mapping assay for detecting genome-wide LOH in prostate tumors. We analyzed two human prostate cell lines, P69SV40Tag (P69) and its tumorigenic subline, M12, and 11 prostate cancer cases. The M12 cells showed LOH in chromosomes 3p12.1-p22.1, 11q22.1-q24.2, 19p13.12, and 19q13.42. All of the prostate cases with informative single-nucleotide polymorphism (SNP) markers showed LOH in 1p31.2, 10q11.21, 12p13.1, 16q23.1-q23.2, 17p13.3, 17q21.31, and 21q21.2. Additionally, a high percentage of cases showed LOH at 6p25.1-p25.3 (75%), 8p22-p23.2, and 10q22.1 (70%). Several tumor suppressor genes (TSGs) have been mapped in these loci. These results demonstrate that the HuSNP mapping assay can serve as an alternative to comparative genomic hybridization for assessing genome-wide LOH and can identify chromosomal regions harboring candidate TSGs implicated in prostate cancer.     

Advanced glycation endproducts promote adhesion molecule (VCAM-1, ICAM-1) expression and atheroma formation in normal rabbits.

BACKGROUND: Reactive glucose-protein intermediates and advanced glycation endproducts (AGEs) are shown to colocalize with atheromatous lesions and to trigger complex chemical and biological responses through interaction with vessel wall elements. In diabetes and renal insufficiency, atherosclerosis is common, as are elevated levels of serum and vascular tissue AGEs. In the present study, AGEs supplied exogenously to normal animals elicited vascular and renal pathology. MATERIALS AND METHODS: Nondiabetic rabbits were injected intravenously with low doses of AGE-modified rabbit serum albumin (AGE-RSA, 16 mg/kg/day) for 4 months alone, or combined with a brief terminal period (2 weeks) of a cholesterol-rich diet (CRD) (2% cholesterol, 10% corn oil). AGE-RSA associated expression of vascular cell adhesion molecules and the development of atheromatous changes within the aorta were determined by immunohistology. RESULTS: The AGE content of aortic tissue increased by 2.2-fold in AGE-treated and by 3.2-fold in AGE + CRD-treated rabbits compared with normal saline-treated control rabbits (p < 0.025 and 0.001, respectively). Serum AGE levels in AGE groups rose up to 3-fold above the controls (p < 0.025 and p < 0.01). Ascending aortic sections from AGE-treated rabbits showed significant focal intimal proliferation, enhanced endothelial cell adhesion with infrequent intimal macrophages. oil-red-O staining lipid deposits and positive focal expression of vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1), a pattern not observed in controls. These AGE-induced changes were markedly enhanced in animals cotreated with AGEs and a brief period of CRD. Lesions consisted of multifocal atheromas, containing foam cells, massive lipid droplets, and strong endothelial expression of VCAM-1 and ICAM-1 restricted to the affected areas. CONCLUSIONS: This study provides in vivo evidence for a causal relationship between chronic AGE accumulation and atherosclerosis independent of diabetic hyperglycemia, and suggests the utility of this animal model for the study of diabetic vascular disease in relation to glycation.     

Role of thrombin in the pathogenesis of atherosclerosis

Atherosclerosis is an arterial disease associated with inflammation. Thrombin is a procoagulant and proinflammatory serine protease that contributes to the pathology of atherosclerosis by enhancing the expression of cell adhesion molecules, inducing the secretion of proinflammatory cytokines, activating inflammatory responses in atherosclerotic plaques, stimulating proliferation of aortic smooth muscle cells, and exacerbating vascular lesions at sites of injury. Hence, thrombin appears to be an important target for treatment of atherosclerosis and thrombin pharmacological inhibitors have significant therapeutic potency for suppressing inflammatory responses in cardiovascular diseases. This review summarizes the proinflammatory signaling functions of thrombin as well as the therapeutic potency of thrombin inhibitors in the pathogenesis of atherosclerosis and hence their potential therapeutic value in this condition.     

Elevated incidence of loss of heterozygosity (LOH) in an sgs1 mutant of Saccharomyces cerevisiae: roles of yeast RecQ helicase in suppression of aneuploidy,interchromosomal rearrangement,and the simultaneous incidence of both events during mitotic growth

The SGS1 gene of Saccharomyces cerevisiae is a member of the RecQ helicase family, which includes the human BLM, WRN and RECQL4 genes responsible for Bloom and Werner's syndrome and Rothmund-Thomson syndrome, respectively. Cells defective in any of these genes exhibit a higher incidence of genome instability. We previously demonstrated that various genetic alterations were detectable as events leading to loss of heterozygosity (LOH) in S. cerevisiae diploid cells, utilizing a hemizygous URA3 marker placed at the center of the right arm of chromosome III. Analyses of chromosome structure in LOH clones by pulse field gel electrophoresis (PFGE) and PCR, coupled with a genetic method, allow identification of genetic alterations leading to the LOH. Such alterations include chromosome loss, chromosomal rearrangements at various locations and intragenic mutation. In this work, we have investigated the LOH events occurring in cells lacking the SGS1 gene. The frequencies of all types of LOH events, excluding intragenic mutation, were increased in sgs1 null mutants as compared to the wild-type cells. Loss of chromosome III and chromosomal rearrangements were increased 13- and 17-fold, respectively. Further classification of the chromosomal rearrangements confirmed that two kinds of events were especially increased in the sgs1 mutants: (1) ectopic recombination between chromosomes, that is, unequal crossing over and translocation (46-fold); and (2) allelic crossing over associated with chromosome loss (40-fold). These findings raise the possibility that the Sgs1 protein is involved in the processing of recombination intermediates as well as in the prevention of recombination repair during chromosome DNA replication. On the other hand, intrachromosomal deletions between MAT and HMR were increased only slightly (2.9-fold) in the sgs1 mutants. These results clearly indicate that defects in the SGS1 gene function lead to an elevated incidence of LOH in multiple ways, including chromosome loss and interchromosomal rearrangements, but not intrachromosomal deletion.     

3-morpholinosydnonimine participates in the attenuation of neointima formation via inhibition of annexin A2-mediated vascular smooth muscle cell migration

3-Morpholinosydnonimine (SIN-1) affects vascular smooth muscle cell migration and proliferation, processes essential for atherosclerosis. However, the mechanism by which SIN-1 exerts these effects has not been elucidated. We used 2-DE followed by MALDI-TOF/TOF MS to identify responses in protein expression to SIN-1 in rat aortic smooth muscle. Platelet-derived growth factor-BB increased cell migration and proliferation in rat aortic smooth muscle cells, and subsequent SIN-1 treatment inhibited it. Administration of SIN-1 in vivo attenuated neointima formation in balloon-injured rat carotid arteries. Proteomic analysis showed that glutathione peroxidase and 40S ribosomal protein S12 were differentially expressed in aortic strips exposed to SIN-1. Expression of annexin A2 was decreased by SIN-1. Platelet-derived growth factor-BB-induced cell migration was increased and inhibited in rat aortic smooth muscle cells with overexpression and knockdown of annexin A2 gene, respectively. The expression of annexin A2 was increased in vascular neointima compared with the intact control, which was inhibited by SIN-1 treatment. These results demonstrate that SIN-1 may attenuate vascular neointima formation by inhibiting annexin A2-mediated migration. Therefore, annexin A2 may be a potential target for therapeutic strategies for atherosclerosis.     

17p13 (p53 locus), 5q21 (APC locus) and 9p21 (p16 locus) allelic deletions are frequently found in oral exfoliative cytology cells from smoker patients with non-small-cell lung cancer

Molecular cytogenetic and LOH analyses of non-small cell lung cancer (NSCLC) have shown frequent allelic deletions in a variety of chromosomes where tumour suppressor genes are located. Allelic loss at 9p21 (p16 locus), 17p13 (p53) and 5q21(APC) has been frequently described in NSCLC and has also been described in premalignant epithelial lesions of the bronchus and normal bronchial cells. These findings suggest that a tissue field of somatic genetic alterations precedes the histopathological phenotypic changes of carcinoma. Similar changes have been described in oral and laryngeal epithelial tumours associated with smoke exposure. We previously reported frequent LOH at 5q21, 9p21 and TP53 in tumor cells and peritumoral normal bronchial cells from surgically resected NSCLC. We now analyze 96 cases of normal oral exfoliative cytology in which normal epithelial cells were obtained: 43 cases from smoker patients with NSCLC diagnosis, 33 smoker patients with no evidence of malignancy and 20 non-smoker patients with no evidence of tumour. All groups had a similar age and sex distribution. PCR amplification was performed utilising the specific markers D5S346, D9S157 and TP53. In normal oral mucosae cells from patients with NSCLC, we found that 21% of the informative cases showed LOH at any of the three analyzed loci distributed as follows: 14.3% of the informative cases showed LOH at 5q21, 7.7% at 9p21 and 22.2% at TP53. Within the smoker risk group only one case (4% of the informative cases) showed LOH at TP53, while no LOH was found at 5q21 or 9p21. No LOH was found in non-smokers. In conclusion, our results show that a significant number of patients with NSCLC have LOH at TP53, 5q21 and 9p21 in normal oral mucosae, while LOH at these loci is unusual in similar cells obtained from patients with no evidence of malignancy. Our study demonstrates that LOH studies can detect smoker patients with a mutated genotype in normal epithelial cells. Further prospective studies may confirm whether LOH studies can detect patients with a higher risk of NSCLC.     

Role of vascular smooth muscle cell in the inflammation of atherosclerosis

Atherosclerosis is a pathologic process occurring within the artery, in which many cell types, including T cell, macrophages, endothelial cells, and smooth muscle cells, interact, and cause chronic inflammation, in response to various inner- or outer-cellular stimuli. Atherosclerosis is characterized by a complex interaction of inflammation, lipid deposition, vascular smooth muscle cell proliferation, endothelial dysfunction, and extracellular matrix remodeling, which will result in the formation of an intimal plaque. Although the regulation and function of vascular smooth muscle cells are important in the progression of atherosclerosis, the roles of smooth muscle cells in regulating vascular inflammation are rarely focused upon, compared to those of endothelial cells or inflammatory cells. Therefore, in this review, we will discuss here how smooth muscle cells contribute or regulate the inflammatory reaction in the progression of atherosclerosis, especially in the context of the activation of various membrane receptors, and how they may regulate vascular inflammation. [BMB Reports 2014; 47(1): 1-7]     

Uhrf2 is important for DNA damage response in vascular smooth muscle cells

Emerging evidence shows that Uhrf1 plays an important role in DNA damage response for maintaining genomic stability. Interestingly, Uhrf1 has a paralog Uhrf2 in mammals. Uhrf1 and Uhrf2 share similar domain architectures. However, the role of Uhrf2 in DNA damage response has not been studied yet. During the analysis of the expression level of Uhrf2 in different tissues, we found that Uhrf2 is highly expressed in aorta and aortic vascular smooth muscle cells. Thus, we studied the role of Uhrf2 in DNA damage response in aortic vascular smooth muscle cells. Using laser microirradiation, we found that like Uhrf1, Uhrf2 was recruited to the sites of DNA damage. We dissected the functional domains of Uhrf2 and found that the TTD, PHD and SRA domains are important for the relocation of Uhrf2 to the sites of DNA damage. Moreover, depletion of Uhrf2 suppressed DNA damage-induced H2AX phosphorylation and DNA damage repair. Taken together, our results demonstrate the function of Uhrf2 in DNA damage response.     

Nicotine promotes atherosclerosis development in apolipoprotein E-deficient mice through α1-nAChR

α1 Nicotinic acetylcholine receptor (α1nAChR) is an important nicotine receptor that is widely distributed in vascular smooth muscle cells, macrophages, and endothelial cells. However, the role of α1nAChR in nicotine-mediated atherosclerosis remains unclear. The administration of nicotine for 12 weeks increased the area of the atherosclerotic lesion, the number of macrophages infiltrating the plaques, and the circulating levels of inflammatory cytokines, such as interleukin-6 and tumor necrosis factor-α, in apolipoprotein E-deficient (ApoE^−/−) mice fed a high-fat diet. Nicotine also increased α1nAChR, calpain-1, matrix metalloproteinase-2 (MMP-2), and MMP-9 expression in the aortic tissue. Silencing of α1nAChR with an adenoassociated virus decreased the atherosclerotic size, lesion macrophage content, and circulating levels of inflammatory cytokines and suppressed α1nAChR, calpain-1, MMP-2, and MMP-9 expression in the nicotine group. In vitro, nicotine-induced α1nAChR, calpain-1, MMP-2, and MMP-9 expression in mouse vascular smooth muscle cells (MOVAS) and macrophages (RAW264.7), and enhanced the migration and proliferation of these cells. The silencing of α1nAChR inhibited these effects of nicotine MOVAS and RAW264.7 cells. Thus, we concluded that nicotine promoted the development of atherosclerosis partially by inducing the migration and proliferation of vascular smooth muscle cells and macrophages and inducing an inflammatory reaction. The effect of nicotine on atherogenesis may be mediated by α1nAChR-induced activation of the calpain-1/MMP-2/MMP-9 signaling pathway.     

Antisense oligonucleotides to stromelysin mRNA inhibit injury-induced proliferation of arterial smooth muscle cells.

Smooth muscle cell migration and proliferation are important events in the formation of intimal lesions associated with atherosclerosis and restenosis following balloon angioplasty. To make this possible, the smooth muscle cell has to change from a contractile to an activated repair cell with capacity to synthesize DNA and extracellular matrix components. There is now considerable evidence that the extracellular matrix has important functions in modulating the phenotypic properties of smooth muscle cells, but less is known about the role of the matrix metalloproteinases. The present study investigates the role of stromelysin in the modulation of rat aortic smooth muscle cell morphology and function following mechanical injury in vitro and in vivo. Antisense mRNA oligonucleotides were used to investigate the role of stromelysin expression in injury-induced phenotypic modulation and the subsequent migration and proliferation of vascular smooth muscle cells. Cultured rat aortic smooth muscle cells and balloon-injured rat carotid arteries were used as experimental models. Light- and electron microscopy were used to follow changes in smooth muscle cell phenotype and lesion formation and incorporation of 3H-thymidine to detect DNA synthesis. Injury-induced DNA synthesis and migration in vitro were inhibited by 72% and 36%, respectively, by adding stromelysin antisense oligonucleotides to the medium prior to injury. In primary cultures, 67% of the smooth muscle cells treated with stromelysin antisense were retained in a contractile phenotype as judged by analysis of cell fine structure, compared to 15% untreated cells and 40% in cells treated with mismatched oligonucleotides. Examination of the carotid arteries one week after balloon injury likewise demonstrated a larger fraction of contractile cells in the inner parts of the media in vessels treated with antisense oligonucleotides compared to those treated with mismatched oligonucleotides. The neointima was also distinctly thinner in antisense-treated than in mismatched-treated and control arteries at this time. These findings indicate that stromelysin mRNA antisense oligonucleotides inhibited phenotypic modulation of rat arterial smooth muscle cells and so caused a decrease in migration and proliferation and neointima formation in response to vessel wall injury.