Outcome of surgical treatment of perineal hernia in cats: 36 cases (2013-2019).

OBJECTIVES: To report the clinical presentation, complications, and long-term outcomes of cats treated for perineal hernia with modified internal obturator muscle transposition. METHODS: The medical records of cats surgically treated for perineal hernia between 2013 and 2019 were reviewed and an owner questionnaire was conducted to determine long-term outcome. RESULTS: Thirty-six cats were included in the study: 34 had bilateral and two unilateral hernias. Of these 36, 24 (67%) were male neutered with a median age of 10 (range: 1 to 18) years. The complication rate was low, however, one cat experienced a major postoperative complication: rectal prolapse requiring revision surgery 48 hours postsurgery. Short-term outcomes were available for 32 of 36 (89%) cats. Of the 32, 23 were examined 6 weeks postoperatively, and a telephonic consultation was performed for an additional nine of 32. Of the 23 cats examined directly, none had recurrence. Overall 12 of 32 experienced short-term postoperative tenesmus which resolved in nine of 12 (75%). Long-term outcomes were available for 31 of 36 cats (86%), with a median of 18.5 (6 to 89) months follow-up. A good outcome was achieved in 23 of 31 (74%) whereas three of 31 (10%) had fair outcomes and five of 31 (16%) had a poor outcome. Of the five cats with a poor outcome, two required subtotal colectomy to manage clinical signs related to megacolon, two were euthanised following a return of clinical signs, and one developed unilateral recurrence. CLINICAL SIGNIFICANCE: Perineal hernia should be considered in cats presenting with tenesmus or recurrent obstipation. Surgical treatment of perineal hernias in cats can result in good owner-assessed long-term outcome.

Genome-wide association study across European and African American ancestries identifies a SNP in DNMT3B contributing to nicotine dependence.

Cigarette smoking is a leading cause of preventable mortality worldwide. Nicotine dependence, which reduces the likelihood of quitting smoking, is a heritable trait with firmly established associations with sequence variants in nicotine acetylcholine receptor genes and at other loci. To search for additional loci, we conducted a genome-wide association study (GWAS) meta-analysis of nicotine dependence, totaling 38,602 smokers (28,677 Europeans/European Americans and 9925 African Americans) across 15 studies. In this largest-ever GWAS meta-analysis for nicotine dependence and the largest-ever cross-ancestry GWAS meta-analysis for any smoking phenotype, we reconfirmed the well-known CHRNA5-CHRNA3-CHRNB4 genes and further yielded a novel association in the DNA methyltransferase gene DNMT3B. The intronic DNMT3B rs910083-C allele (frequency=44-77%) was associated with increased risk of nicotine dependence at P=3.7 × 10-8 (odds ratio (OR)=1.06 and 95% confidence interval (CI)=1.04-1.07 for severe vs mild dependence). The association was independently confirmed in the UK Biobank (N=48,931) using heavy vs never smoking as a proxy phenotype (P=3.6 × 10-4, OR=1.05, and 95% CI=1.02-1.08). Rs910083-C is also associated with increased risk of squamous cell lung carcinoma in the International Lung Cancer Consortium (N=60,586, meta-analysis P=0.0095, OR=1.05, and 95% CI=1.01-1.09). Moreover, rs910083-C was implicated as a cis-methylation quantitative trait locus (QTL) variant associated with higher DNMT3B methylation in fetal brain (N=166, P=2.3 × 10-26) and a cis-expression QTL variant associated with higher DNMT3B expression in adult cerebellum from the Genotype-Tissue Expression project (N=103, P=3.0 × 10-6) and the independent Brain eQTL Almanac (N=134, P=0.028). This novel DNMT3B cis-acting QTL variant highlights the importance of genetically influenced regulation in brain on the risks of nicotine dependence, heavy smoking and consequent lung cancer.

Pathways to smoking behaviours: biological insights from the Tobacco and Genetics Consortium meta-analysis.

By running gene and pathway analyses for several smoking behaviours in the Tobacco and Genetics Consortium (TAG) sample of 74 053 individuals, 21 genes and several chains of biological pathways were implicated. Analyses were carried out using the HYbrid Set-based Test (HYST) as implemented in the Knowledge-based mining system for Genome-wide Genetic studies software. Fifteen genes are novel and were not detected with the single nucleotide polymorphism-based approach in the original TAG analysis. For quantity smoked, 14 genes passed the false discovery rate of 0.05 (corrected for multiple testing), with the top association signal located at the IREB2 gene (P=1.57E-37). Three genomic loci were significantly associated with ever smoked. The top signal is located at the noncoding antisense RNA transcript BDNF-AS (P=6.25E-07) on 11p14. The SLC25A21 gene (P=2.09E-08) yielded the top association signal in the analysis of smoking cessation. The 19q13 noncoding RNA locus exceeded the genome-wide significance in the analysis of age at initiation (P=1.33E-06). Pathways belonging to the Neuronal system pathways, harbouring the nicotinic acetylcholine receptor genes expressing the α (CHRNA 1-9), ß (CHRNB 1-4), γ, δ and ɛ subunits, yielded the smallest P-values in the pathway analysis of the quantity smoked (lowest P=4.90E-42). Additionally, pathways belonging to 'a subway map of cancer pathways' regulating the cell cycle, mitotic DNA replication, axon growth and synaptic plasticity were found significantly enriched for genetic variants in ever smokers relative to never smokers (lowest P=1.61E-07). In addition, these pathways were also significantly associated with the quantity smoked (lowest P=4.28E-17). Our results shed light on one of the world's leading causes of preventable death and open a path to potential therapeutic targets. These results are informative in decoding the biological bases of other disease traits, such as depression and cancers, with which smoking shares genetic vulnerabilities.

Testing Causal Effects of Maternal Smoking During Pregnancy on Offspring's Externalizing and Internalizing Behavior.

Maternal smoking during pregnancy (SDP) is associated with increased risk of externalizing and internalizing behaviors in offspring. Two explanations (not mutually exclusive) for this association are direct causal effects of maternal SDP and the effects of genetic and environmental factors common to parents and offspring which increase smoking as well as problem behaviors. Here, we examined the associations between parental SDP and mother rated offspring externalizing and internalizing behaviors (rated by the Child Behavior Checklist/2-3) at age three in a population-based sample of Dutch twins (N = 15,228 pairs). First, as a greater effect of maternal than of paternal SDP is consistent with a causal effect of maternal SDP, we compared the effects of maternal and paternal SDP. Second, as a beneficial effect of quitting smoking before pregnancy is consistent with the causal effect, we compared the effects of SDP in mothers who quit smoking before pregnancy, and mothers who continued to smoke during pregnancy. All mothers were established smokers before their pregnancy. The results indicated a greater effect of maternal SDP, compared to paternal SDP, for externalizing, aggression, overactive and withdrawn behavior. Quitting smoking was associated with less externalizing, overactive behavior, aggression, and oppositional behavior, but had no effect on internalizing, anxious depression, or withdrawn behavior. We conclude that these results are consistent with a causal, but small, effect of smoking on externalizing problems at age 3. The results do not support a causal effect of maternal SDP on internalizing behaviors.

Effect of cervical cerclage on rate of cervical shortening.

OBJECTIVE: Although cerclage has been shown to reduce the risk of recurrent preterm birth in a high-risk patient population, the mechanism by which this occurs is not well understood. Our objective was to evaluate whether cerclage affects the rate of cervical shortening taking into account exposure to 17-hydroxyprogesterone and vaginal progesterone. METHODS: This was a retrospective cohort study of women who had serial cervical length measurements due to a history of spontaneous preterm delivery. Demographic data, obstetric history, progesterone administration, delivery information and serial cervical length measurements were collected. The rate of cervical shortening was compared in women with and without cerclage. Subgroup analyses were performed to compare rates of cervical shortening by indication for cerclage (history indicated vs ultrasound indicated) and outcome in the current pregnancy (cerclage vs no cerclage among those who delivered preterm). RESULTS: A total of 414 women were included of whom 32.4% (n = 134) had a cerclage. There was no difference in the rate of cervical shortening between the cerclage (0.8 mm/week) and no-cerclage (1.0 mm/week, P = 0.43) groups. The rates of cervical shortening among history-indicated and ultrasound-indicated cerclage groups were similar (0.9 vs 1.3 mm/week, respectively, P = 0.2). Among patients with a preterm delivery in the index pregnancy, the rates of cervical shortening among those with (1.31 mm/week) and without (1.28 mm/week, P = 0.78) cerclage were also similar. CONCLUSION: Cervical shortening among women with cerclage occurs at a similar rate to that among women without a cerclage, regardless of indication for cerclage or pregnancy outcome.

Efficient nucleus detector in histopathology images.

In traditional cancer diagnosis, (histo)pathological images of biopsy samples are visually analysed by pathologists. However, this judgment is subjective and leads to variability among pathologists. Digital scanners may enable automated objective assessment, improved quality and reduced throughput time. Nucleus detection is seen as the corner stone for a range of applications in automated assessment of (histo)pathological images. In this paper, we propose an efficient nucleus detector designed with machine learning. We applied colour deconvolution to reconstruct each applied stain. Next, we constructed a large feature set and modified AdaBoost to create two detectors, focused on different characteristics in appearance of nuclei. The proposed modification of AdaBoost enables inclusion of the computational cost of each feature during selection, thus improving the computational efficiency of the resulting detectors. The outputs of the two detectors are merged by a globally optimal active contour algorithm to refine the border of the detected nuclei. With a detection rate of 95% (on average 58 incorrectly found objects per field-of-view) based on 51 field-of-view images of Her2 immunohistochemistry stained breast tissue and a complete analysis in 1 s per field-of-view, our nucleus detector shows good performance and could enable a range of applications in automated assessment of (histo)pathological images.

Genome-wide association analysis of coffee drinking suggests association with CYP1A1/CYP1A2 and NRCAM.

Coffee consumption is a model for addictive behavior. We performed a meta-analysis of genome-wide association studies (GWASs) on coffee intake from 8 Caucasian cohorts (N=18 176) and sought replication of our top findings in a further 7929 individuals. We also performed a gene expression analysis treating different cell lines with caffeine. Genome-wide significant association was observed for two single-nucleotide polymorphisms (SNPs) in the 15q24 region. The two SNPs rs2470893 and rs2472297 (P-values=1.6 × 10(-11) and 2.7 × 10(-11)), which were also in strong linkage disequilibrium (r(2)=0.7) with each other, lie in the 23-kb long commonly shared 5' flanking region between CYP1A1 and CYP1A2 genes. CYP1A1 was found to be downregulated in lymphoblastoid cell lines treated with caffeine. CYP1A1 is known to metabolize polycyclic aromatic hydrocarbons, which are important constituents of coffee, whereas CYP1A2 is involved in the primary metabolism of caffeine. Significant evidence of association was also detected at rs382140 (P-value=3.9 × 10(-09)) near NRCAM-a gene implicated in vulnerability to addiction, and at another independent hit rs6495122 (P-value=7.1 × 10(-09))-an SNP associated with blood pressure-in the 15q24 region near the gene ULK3, in the meta-analysis of discovery and replication cohorts. Our results from GWASs and expression analysis also strongly implicate CAB39L in coffee drinking. Pathway analysis of differentially expressed genes revealed significantly enriched ubiquitin proteasome (P-value=2.2 × 10(-05)) and Parkinson's disease pathways (P-value=3.6 × 10(-05)).

Proteasome inhibition as novel treatment strategy in leukaemia.

Following its success in multiple myeloma (MM), proteasome inhibition has become a topic of interest as novel treatment strategy of cancer. By simultaneously affecting multiple pathways in the cancer cell, such as deregulation of the programmed degradation of many cellular proteins, proteasome inhibition causes rapid apoptosis of these cells. Both in rapidly proliferating leukaemic cell lines and in primary leukaemic cells isolated from patients, proteasome inhibition results in antileukaemic activity. The normal counterparts of these cells are much more resistant to proteasome inhibitors (PI), thereby resulting in a favourable therapeutic index. Importantly, while leukaemic stem cells are sensitive to proteasome inhibition, normal haematopoietic stem cells are still viable after drug exposure. Nowadays, many PIs are being identified; bortezomib is the most well known since obtaining Food and Drug Administration approval for clinical use in MM. This review summarises the biological and clinical aspects of proteasome inhibition and discusses the potential role of these inhibitors in the treatment of leukaemia.

Heritability of polycystic ovary syndrome in a Dutch twin-family study.

BACKGROUND: Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders among women of reproductive age. There is evidence for a genetic component in PCOS based on familial clustering of cases. OBJECTIVE: In the present study, the heritability of PCOS was estimated. DESIGN/PARTICIPANTS: Data from 1332 monozygotic twins (genetically identical) and 1873 dizygotic twins/singleton sisters of twins (who share on average 50% of their segregating genes) registered with The Netherlands Twin Register were used. PCOS was defined as less than nine menstrual cycles and acne or hirsutism in agreement with the 2003 Rotterdam consensus. RESULTS: Results point to a strong contribution of familial factors to PCOS. The resemblance in monozygotic twin sisters (tetrachoric correlation 0.71) for PCOS was about twice as large as in dizygotic twin and other sisters (tetrachoric correlation 0.38). Univariate analyses point to strong contributions of genetic factors to the variance in PCOS. Next, a trivariate genetic analysis of oligomenorrhea, acne, and hirsutism was carried out. This analysis confirmed that the familial component in PCOS is due to genetic factors. CONCLUSIONS: This study demonstrated a large influence of genetic factors to the pathogenesis of PCOS, justifying the search for susceptibility genes.

Linkage analysis of smoking initiation and quantity in Dutch sibling pairs.

The heritability of smoking initiation (SI) and number of cigarettes smoked (NC) was determined in 3657 Dutch twin pairs. For SI a heritability of 36% was found and for NC of 51%. Both SI and NC were also significantly influenced by environmental factors shared by family members. The etiological factors that influence these traits partly overlap. Linkage analyses were performed on data of 536 DZ twins and siblings from 192 families, forming 592 sibling pairs. Results suggested QTLs on chromosome 6 (LOD=3.05) and chromosome 14 (LOD=1.66) for SI and on chromosome 3 (LOD=1.98) for NC. Strikingly, on chromosome 10 a peak was found in the same region for both SI (LOD=1.92) and for NC (LOD=2.29) which may partly explain the overlapping etiological factors for SI and NC.

Multiple primary melanomas.

BACKGROUND: Patients with clinically diagnosed dysplastic nevi or a family history of melanoma with or without histologically diagnosed dysplastic nevi seem to be at higher risk for the development of multiple melanomas. OBJECTIVE: Our purpose was to determine which factors increased the risk for the development of subsequent melanomas. METHODS: This was a retrospective study in 56 patients with 157 melanomas. RESULTS: Early age at onset (58.9%), clinically diagnosed dysplastic nevi (82.0%), a histologically diagnosed dysplastic nevus (64%), family history of clinically diagnosed dysplastic nevi (70.8%) or melanoma (64.7%) and a histologically diagnosed dysplastic nevus in combination with a family history of melanoma (48%) were found in a high percentage of patients. The mean age at diagnosis was 38.2 years. The mean interval between the first and second melanoma was 34.3 months. Of the second melanomas, 76.8% developed in a different anatomic region from the first melanomas. The mean tumor thickness (Breslow) decreased from 1.11 mm for the first melanomas to 0.90 mm for the second melanomas. CONCLUSION: The results suggest that genetic factors might be involved in a certain subset of patients in whom melanomas develop early and successively.

Effect of topical tretinoin under occlusion on atypical naevi.

Atypical naevi are potential precursors of melanoma and markers of increased melanoma risk. To examine the possibility of chemoprevention of melanoma by retinoids, we studied the effect of topical tretinoin 0.1% (all-transretinoic acid; vitamin A acid) and tretinoin 0.1% with hydrocortisone on atypical naevi. Thirty patients with atypical naevi were enrolled in a prospective randomized double blind study. For each patient three comparable naevi were selected and randomized to receive tretinoin 0.1% (T), tretinoin 0.1% with hydrocortisone 1% (C) or a placebo cream (P) once a week under Actiderm occlusion for 4 months. Baseline views of the naevi, taken with a videomicroscope (magnification 20 x), were assessed for morphological changes compared with views taken 2 months after the beginning of treatment, 1 week after completion of treatment and 6 months later. After completion of the study all naevi in the T and C groups and six naevi in the P group were removed and evaluated histologically for the presence of atypia. The number of naevi that had changed in colour or size was significantly higher in the T and C groups compared with the placebo group. A size reduction took place in 42.9% (T) and 40.0% (C) of the naevi and the colour changed in 75.0% (T) and 66.7% (C). The effect of treatment, in general subtle, did not differ significantly between groups T and C, but naevi treated with C became significantly less irritated. Histologically, 75.0% of the naevi treated with T and 69.6% of the naevi treated with C were atypical. Therefore, no major change was seen in the clinical aspect of atypical naevi after treatment with tretinoin 0.1% or tretinoin with hydrocortisone 1%, and most of the treated naevi still met the histological criteria for atypia after the treatment period. The current management of follow-up of atypical naevi and excision when change to melanoma is suspected is therefore still recommended. Nevertheless, some response was seen, which may justify a further exploration of tretinoin and hydrocortisone 1% therapy for a longer treatment period in combination with research to clarify its mechanism.

Characterization of interleukin-1 alpha-induced melanoma cell motility: inhibition by type I and type II receptor-blocking monoclonal antibodies.

Interleukin-1 alpha (IL-1 alpha) induces cell motility in a variety of benign cell types and in some but not all malignant cell lines in vitro. This study characterizes the IL-1 alpha-induced motility of an aggressive human melanoma cell line that expresses both type I and type II IL-1 receptors. We tested the effect of monoclonal antibodies including function-blocking moAbs against the type I and type II IL-1 receptors on melanoma cell motility to determine which receptor is involved in signal transduction of IL-1 alpha-induced melanoma cell motility. IL-1 alpha significantly increases MM-RU melanoma cell migration in a dose-dependent manner using modified Boyden chamber assays at concentrations 10 to 100 times less than concentrations that significantly inhibit cell growth. Computer-assisted time-lapse image analysis reveals that the motility is inhibited in a dose-dependent manner by neutralizing antibodies against IL-1 alpha. Function-blocking monoclonal antibodies against either type I or type II IL-1 receptors show a significant inhibition of cytokine-induced enhanced cell migration. When both the anti-IL-1 receptor antibodies are added together, the motility-response is completely blocked to control levels. Taken together the data indicate that the IL-1 alpha-induced motility of MM-RU melanoma cells is mediated through both type I and type II IL-1 receptors. The significant inhibition of motility by neutralizing IL-1 alpha or blocking either one or both of the IL-1 receptors indicates an integration of IL-1-induced signals in the induction of melanoma cell migration.

Role of beta 1 integrins in cell spreading and migration of human nevomelanocytes and dysplastic nevi cells on collagen type IV and laminin.

We characterized beta 1 integrin subunit expression on three different cultures of benign human nevomelanocytes (NMC) and on four different cell cultures of human dysplastic nevus (DN) cells by flow cytometry analysis and examined their role in mediating cell spreading and migration on collagen type IV (CN IV) and laminin (LN) coated substrates by using a quantitative video image analysis system. The seven human NMC and DNC cultures expressed heterogeneous levels of beta 1, alpha 2, alpha 3 and alpha 6 integrin subunits. Image analysis showed that a significant increase (P < 0.001) in cell spreading and migration of the DN cells was induced on increasing coating concentrations of CN IV and LN. However, the NMC did not show an increase in cell spreading or migration on these substrates when compared to the substrates coated with denatured BSA only. The CN IV-induced cell spreading of the DN cells was significantly inhibited by anti-beta 1 mAb (AIIB2), anti-alpha 2 mAb (P1E6), or anti-alpha 3 mAb (P1B5), but not by mAb against alpha 6 integrin subunit (GoH3). The DN cell spreading on LN was not significantly inhibited by these mAbs. In contrast, the migration of the DN on CN IV and LN was significantly inhibited by anti-beta 1 mAb, anti-alpha 2 mAb, anti-alpha 3 mAb and anti-alpha 6 mAb. These data suggest that the alpha 2 and alpha 3 subunit are important for cell spreading of the DN on CN IV, although they are less important in cell spreading on the extracellular matrix component LN.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential effects of interleukin 1-alpha (IL-1 alpha) or tumor necrosis factor-alpha (TNF-alpha) on motility of human melanoma cell lines on fibronectin.

Interleukin-1 alpha (IL-1 alpha) and tumor necrosis factor-alpha (TNF-alpha) induce a motogenic response in a number of benign and malignant cells. We examined the chemokinetic effects of these cytokines on the cell migration of four melanoma cell lines on fibronectin using modified Boyden chambers and video-time lapse analysis. Flow cytometry analysis of IL-1 receptors, TNF receptors, and shifts in beta 1 integrin expression were correlated with the effects of these cytokines on cell migration on fibronectin. The four melanoma cell lines exhibited heterogeneous expression of types I and II IL-1 receptors as well as p60 TNF receptors. Scant p80 TNF receptor expression was detected on only one cell line. Three of four melanoma cell lines demonstrated type I IL-1 receptors by Western blotting. IL-1 alpha and TNF-alpha induced heterogeneous modulation of beta 1 integrin expression in the four melanoma cell lines tested; downward shift of the alpha 2, alpha 3, alpha 4, and beta 1 integrin subunits was detected among three of the melanoma cell lines as were upward shifts of the alpha 4, alpha 5, and alpha 6 integrin subunits among three of the melanoma cell lines. IL-1 alpha and TNF-alpha induced enhanced migration on fibronectin in one of the melanoma cell lines and were related to an upward shift in the alpha 4 and alpha 5 integrin subunit expression. Taken together, the findings indicate that expression of a particular receptor for IL-1 or TNF does not necessarily signal a motogenic response in melanoma cells, but induces heterogeneous shifts in beta 1 integrin expression. However, upregulation in alpha 4 and alpha 5 integrin subunits appears to relate to enhanced migration on fibronectin.

Role of alpha 3 beta 1 and alpha 2 beta 1 integrins in melanoma cell migration.

Recent findings indicate that variable expression of beta 1 integrins may play a role in differential melanoma cell motility. Primary melanoma (PM) and metastatic melanoma (MM) cultures, derived from the same patient, were tested for their beta 1, alpha 2, alpha 3 and alpha 6 integrin subunit expression and cell migration on type IV collagen (CN IV) or laminin (LN). The MM cell line expressed markedly increased levels of the beta 1, alpha 2 and alpha 3, but not alpha 6 subunit compared to the PM cell line. The MM cell migration rate was significantly higher than that of the PM cell line on LN- or CN IV-coated substrates. Furthermore, the cell migration rate of both lines was significantly higher (p < 0.001) on these substrates than on the control substrates. The MM and PM cell migration was significantly inhibited by function-blocking anti-beta 1 and anti-alpha 3 MAbs, but not by the anti-alpha 6 MAb tested. In contrast, the anti-alpha 2 MAb significantly inhibited MM but not PM cell migration. These data show that the alpha 3 subunit plays a significant role in melanoma cell motility on CN IV and LN and that the alpha 2 subunit has a significant contribution to the motility of the MM cell line.

Role of beta-1 integrins in organ specific adhesion of melanoma cells in vitro.

BACKGROUND: Recent data suggest that the extracellular matrix of organs and heterogeneous integrin expression of tumor cells may influence metastasis distribution. EXPERIMENTAL DESIGN: Three human melanoma cell lines were characterized for integrin expression, in vitro binding to cryostat sections of different organs, and ability to generate experimental metastases in triple immunodeficient mice. RESULTS: The three cell lines exhibited heterogeneous expression of integrins, binding to cryostat sections, and organ colonization. A primary melanoma cell line (PM-WK) did not give rise to experimental metastases, showed scant or mild attachment to only a few organ tissue sections, and showed absent or minimal expression of alpha-integrin subunits tested (VLA 1-6) and alpha v beta 3. In contrast, two lymph node derived lines exhibited distinct patterns of organ colonization: MM-RU colonized only the lungs and expressed predominantly alpha 2 beta 1 and alpha v beta 3 integrin, whereas MM-AN colonized lung and extrapulmonary sites including pancreas and subcutaneous brown fat and expressed predominantly alpha 2 beta 1 and alpha 6 beta 1 integrin. In vitro, MM-RU exhibited marked attachment to lung, brown fat, kidney, and adrenal with no binding to liver, pancreas, brain, or muscle tissue sections, whereas MM-AN had a similar binding profile but with additional attachment to liver and pancreas. Function blocking anti-beta 1 monoclonal antibody inhibited the attachment of MM-RU and MM-AN cells to these tissues (p < 0.001), whereas function blocking anti-alpha 5 and an unrelated monoclonal antibody (HLA class I) did not. Function blocking anti-alpha 2 monoclonal antibody inhibited MM-RU cell adhesion (p < 0.001) but not MM-AN adhesion. However, the function blocking monoclonal antibody alpha 6 beta 1 significantly inhibited the binding of MM-AN to these tissues. CONCLUSIONS: These data suggest that alpha 2 beta 1 and alpha 6 beta 1 mediate differential melanoma cell attachment to organ tissue sections in vitro and that differences in integrin expression of these melanoma cells may be involved in differential organ colonization in vivo.

Actin organization and cell migration of melanoma cells relate to differential expression of integrins and actin-associated proteins.

We have recently described marked differences in cell migration rates and organization of actin in human melanoma cell lines isolated from various stages of tumor progression. Metastatic lines derived from lymph node metastases organized actin into stress fiber arrays and had high mean migration rates in vitro when compared to lines from other stages. Melanoma cells also reveal marked differences in localization of alpha-actinin and beta 1 integrins at stress fiber termination sites (focal contacts). Disruption of this organization is induced by antibodies against beta 1 integrins, alpha-actinin, recently postulated as having a role in linkage of actin to beta 1 integrins, is differentially expressed in melanoma cells by Northern blot analysis and a relatively high alpha-actinin to actin ratio is associated with stress fiber formation and increased cell migration. Furthermore, actin-binding protein, which cross-links actin filaments, is also significantly increased in lines exhibiting high migration rates. Control of migration and actin organization may be mediated by extracellular matrices and/or modulation of actin-associated proteins including alpha-actinin and actin binding protein. These findings provide evidence that an interaction of transmembrane adhesion molecules and elements of the cytoskeleton in melanoma cells may be responsible for differences in migration rates and capacity for metastasis.