The efficacy of eribulin mesylate for patients with cutaneous angiosarcoma previously treated with taxane: a multicentre prospective observational study.

BACKGROUND: Taxanes are the current first-line treatment for advanced cutaneous angiosarcoma (CAS) for patients who are considered difficult to treat with doxorubicin owing to advanced age or comorbidity. However, no effective second-line therapy for such patients has been established. METHODS: We designed a single-arm prospective observational study of eribulin mesylate (ERB) administered at a dose of 1·4 mg m-2 on days 1 and 8 in a 21-day cycle. Patients with advanced CAS who were previously treated with a taxane and were scheduled to begin ERB treatment were enrolled. The primary endpoint was overall survival (OS) and the secondary endpoints were response rate (RR), progression-free survival (PFS) and toxicity assessment. RESULTS: We enrolled a total of 25 patients. The median OS and PFS were 8·6 months and 3·0 months, respectively. The best overall RR was 20% (five of 25). In total, 16 grade 3/4 severe adverse events (SAEs) occurred; however, all patients recovered. Patients who achieved partial response or stable disease as best response had longer OS than those with progressive disease (median OS not reached and 3·3 months, respectively; P < 0·001). Patients who did not experience SAEs showed longer OS than those who did (median OS 18·8 months and 7·5 months, respectively; P < 0·05). Patients with distant metastasis had shorter median OS than those with locoregional disease, but without statistically significant difference. CONCLUSIONS: ERB showed a promising RR and is a potential candidate for second-line treatment for patients with CAS, after treatment with taxanes. However, owing to the occurrence of SAEs in over half of the participants, caution should be exercised regarding ERB use in elderly patients. What is already known about this topic? Taxanes are the current first-line treatment for patients with advanced cutaneous angiosarcoma (CAS) who are considered difficult to treat with doxorubicin owing to advanced age or comorbidity. No effective therapy for taxane-resistant CAS has been established thus far. Eribulin suppresses microtubule polymerization and elicits an antitumour effect similar to that of taxanes. What does this study add? In our single-arm prospective observational study to evaluate the efficacy of eribulin for treating patients with advanced CAS who previously received taxanes, the median overall survival and progression-free survival were 8·6 and 3·0 months, respectively. Response rates at weeks 7, 13 and 25 were 20%, 17% and 14%, respectively. Although 16 grade 3/4 severe adverse events occurred, all patients recovered. Eribulin showed a promising response rate and is a potential candidate for second-line treatment in CAS after taxane treatment. Linked Comment: Smrke and Benson. Br J Dermatol 2020; 183:797-798.

Three patients with advanced cutaneous angiosarcoma treated with eribulin: investigation of serum soluble CD163 and chemokine (C-X-C motif) ligand 10 as possible biomarkers predicting the biological behaviour of angiosarcoma.

Cutaneous angiosarcoma (CAS) is a highly aggressive vascular tumour that recurs locally and metastasizes early. Although chemoradiotherapy with taxanes shows a high response rate with prolonged survival, second-line therapy for advanced CAS remains contentious. This report describes three patients with advanced CAS treated with eribulin. In addition, we investigated serum soluble (s)CD163, chemokine (C-X-C motif) ligand 10 (CXCL10) and chemokine (C-C motif) ligand 2 levels at several time points of tumour progression in these patients, revealing serum levels of sCD163 and CXCL10 as potential biomarkers for progression of CAS.

Possible mechanisms of the crosstalk between Langerhans cells and regulatory T cells in extramammary Paget disease by receptor activator of nuclear factor kappa B (RANK) ligand/RANK pathways.

BACKGROUND: Extramammary Paget disease (EMPD) is a skin adenocarcinoma of apocrine gland origin, in which Paget cells express receptor activator of nuclear factor kappa B (RANK) ligand (RANKL) and matrix metalloproteinase (MMP)-7, and release soluble (s)RANKL into the tumour microenvironment. We previously reported that about 60% of the RANK+ cells among the stromal cells are M2 macrophages, but the identity of the remaining population of RANK+ cells is still unknown. OBJECTIVES: To investigate the unknown subpopulation of RANK-expressing cells in EMPD. METHODS: The main population of RANK-expressing cells in the epidermis was composed of epidermal Langerhans cells (LCs). To explore the effects of RANKL on LCs, we stimulated LCs generated from human CD34+ hematopoietic progenitor cells with graded concentrations of sRANKL. To further examine the correlation between LCs and regulatory T cells (Tregs) in EMPD, we employed immunohistochemical staining. RESULTS: sRANKL stimulation was shown to augment the production of C-C motif chemokine ligand 17 (CCL17) from LCs. We additionally demonstrated CCL17 expression by CD1a+ LCs in EMPD in an immunofluorescence study. Spearman's rank correlation test confirmed a correlation between the number of LCs and the number of Foxp3+ Tregs in the lesional skin of invasive EMPD. In addition, the numbers of Foxp3+ Tregs in the sentinel lymph nodes of metastatic EMPD were significantly higher than those of metastatic melanoma, which did not express RANKL. CONCLUSIONS: The findings suggest that the RANKL/RANK pathway in EMPD might contribute to the recruitment of Tregs and to maintenance of the tumour microenvironment.

Increased systemic inflammatory interleukin-1ß and interleukin-6 during agitation as predictors of Alzheimer's disease.

OBJECTS: Identification of biomarkers for Alzheimer's disease (AD) is important for its early diagnosis and prevention and a key in advancing our understanding of its pathophysiology. The aim of this study was to determine whether systemic inflammatory interleukin-1ß (IL-1ß) and interleukin-6 (IL-6) as well as hypertension (HT), diabetes mellitus (DM), and body mass index (BMI) are predictors of AD. METHODS: We performed a 10-year follow-up study on 133 elderly who were institutionalized in a nursing home. The associations of IL-1ß and IL-6 at both rest and agitation, as well as HT, DM, and BMI at baseline, were analyzed with the incidences of vascular dementia (VD) and AD during a 10-year follow-up period. RESULTS: The Kaplan-Meier method with log-rank test and Cox regression analyses for the total of 133 subjects showed significantly higher incidences of both VD and AD in subjects with DM or HT at baseline. Resting IL-1ß or IL-6 value, or agitation score, was not significantly associated with the subsequent development of VD or AD. The analyses of 40 subjects who had shown agitation at least once in the previous 3 months demonstrated that IL-1ß and IL-6 values at the agitation stage were significantly associated with AD, but not with VD. CONCLUSION: Our results indicate that systemic inflammatory IL-1ß and IL-6 at the agitation stage are risk factors for the development of AD, but not VD. Inflammatory mechanisms for AD seem to be causal and specific to the development of AD.

Expression of CD39/Entpd1 on granuloma-composing cells and induction of Foxp3-positive regulatory T cells in sarcoidosis.

BACKGROUND: Regulatory T cells (Tregs), together with tolerogenic dendritic cells (tDCs) are involved in maintaining peripheral tolerance. A recent report suggested both Tregs and tDCs may be pathogenic in granulomatous skin disorders. AIM: To examined the expression of CD39 on granuloma-composing cells and Foxp3-positive Tregs in the skin in two representative granulomatous diseases, sarcoidosis and granuloma annulare (GA). METHODS: We immunohistologically examined expression of CD39 on granuloma-composing cells and expression of Foxp3 on CD4+ or CD25+ cells in fixed sections of lesional skin from 16 patients with sarcoidosis and five patients with GA. RESULTS: The granuloma-composing cells expressed CD39 in both sarcoidosis and GA. Significant numbers of CD4+ Foxp3+ Tregs were present diffusely throughout the granulomatous tissues in sarcoidosis, whereas Tregs in GA existed only at the peripheral lesion of palisading granulomatous tissue. CONCLUSIONS: There was infiltration of increased numbers of Foxp3+ Tregs around the CD39+ granuloma-composing cells in both GA and sarcoidosis.

Association between altered systemic inflammatory interleukin-1beta and natural killer cell activity and subsequently agitation in patients with Alzheimer disease.

OBJECTIVE: Alzheimer's disease (AD) is a neurodegenerative disorder that is the most common cause of dementia in the elderly and is frequently accompanied by emotional disorder, including agitation. Although evidence of neuroendocrine immune and inflammatory functions during emotional changes has been accumulated, the pathogenic mechanisms in the development of agitation accompanied by AD remain to be elucidated. METHODS: To clarify the involvement of neuroendocrine and immune and inflammatory systems in agitation in AD, we examined agitation levels, circadian rhythms of behavior, cortisol, interleukin-1beta (IL-1beta), and natural killer cell activity (NKCA) in controls without dementia and 16 AD patients who were recognized to be easily agitated in their nursing homes. These behavioral and blood indicators were assessed according to the progress of the stage of agitation in 16 AD patients (stable, pre-agitation, and agitation stages). RESULTS: Elevations in night behavior and blood cortisol, IL-1beta and an reduced blood NKCA level in the evening were observed not only in the agitation stage, but also when stable in AD patients as compared to the control. Increased IL-1beta and decreased NKCA occurred in both the morning and evening in pre-agitation and agitation stages in AD. CONCLUSIONS: The increased IL-1beta and decreased NKCA with the progress of agitation in AD suggest that inflammation produces agitation and aggravates AD.

Correlation of antiangiogenic and antitumor efficacy of N-biphenyl sulfonyl-phenylalanine hydroxiamic acid (BPHA), an orally-active, selective matrix metalloproteinase inhibitor.

The antiangiogenic activity and antitumor efficacy of a newly developed matrix metalloproteinase (MMP) inhibitor were examined. N-biphenyl sulfonyl-phenylalanine hydroxiamic acid (BPHA) potently inhibits MMP-2, -9, and -14, but not MMP-1, -3, or -7. In contrast, (-)BPHA, an enantiomer of BPHA, was inactive against all MMPs tested. Daily oral administration of 200 mg/kg BPHA, but not (-)BPHA in mice resulted in potent inhibition of tumor-induced angiogenesis, primary tumor growth, and liver metastasis. The growth inhibition activity of BPHA was 48% and 45% in a B16-BL6 melanoma and F2 hemangio-endothelioma model, respectively. BPHA also showed 42% inhibition of the liver metastasis of C-1H human colon carcinoma cells. These results indicate that selective MMP inhibition is correlated with antiangiogenic and antitumor efficacy and that the selective MMP inhibitor BPHA has therapeutic potential.

High-Resolution C-Arm CT and Metal Artifact Reduction Software: A Novel Imaging Modality for Analyzing Aneurysms Treated with Stent-Assisted Coil Embolization.

BACKGROUND AND PURPOSE: Combination of high-resolution C-arm CT and novel metal artifact reduction software may contribute to the assessment of aneurysms treated with stent-assisted coil embolization. This study aimed to evaluate the efficacy of a novel Metal Artifact Reduction prototype software combined with the currently available high spatial-resolution C-arm CT prototype implementation by using an experimental aneurysm model treated with stent-assisted coil embolization. MATERIALS AND METHODS: Eight experimental aneurysms were created in 6 swine. Coil embolization of each aneurysm was performed by using a stent-assisted technique. High-resolution C-arm CT with intra-arterial contrast injection was performed immediately after the treatment. The obtained images were processed with Metal Artifact Reduction. Five neurointerventional specialists reviewed the image quality before and after Metal Artifact Reduction. Observational and quantitative analyses (via image analysis software) were performed. RESULTS: Every aneurysm was successfully created and treated with stent-assisted coil embolization. Before Metal Artifact Reduction, coil loops protruding through the stent lumen were not visualized due to the prominent metal artifacts produced by the coils. These became visible after Metal Artifact Reduction processing. Contrast filling in the residual aneurysm was also visualized after Metal Artifact Reduction in every aneurysm. Both the observational (P < .0001) and quantitative (P < .001) analyses showed significant reduction of the metal artifacts after application of the Metal Artifact Reduction prototype software. CONCLUSIONS: The combination of high-resolution C-arm CT and Metal Artifact Reduction enables differentiation of the coil mass, stent, and contrast material on the same image by significantly reducing the metal artifacts produced by the platinum coils. This novel image technique may improve the assessment of aneurysms treated with stent-assisted coil embolization.

Cloning of the cDNA and the genomic DNA of the mouse angiotensin II type 2 receptor.

Of the two major isoforms of the angiotensin II receptors, type 1 (AT1) and type 2 (AT2), little is known about the structure and features of AT2. We cloned a mouse AT2 cDNA from a mouse fetus cDNA library and an AT2 genomic DNA from a 129SV mouse genomic DNA library. The amino acid sequence of the mouse AT2 (363 residues) deduced from a mouse cDNA clone showed seven membrane-spanning domains. Amino acid identity of the mouse AT2 with mouse AT1 is 37%, and 98% with rat AT2. The genomic DNA (4.4 kb) contained three exons and two introns and the entire coding region was contained in the third exon.

Safety, tolerability and pharmacokinetics of oral S-3304, a novel matrix metalloproteinase inhibitor, in single and multiple dose escalation studies in healthy volunteers.

OBJECTIVE: A novel sulfonamide derivative, S-3304, was discovered as a potent matrix metalloproteinase (MMP) inhibitor. It is a more specific inhibitor to MMP-2 and MMP-9 (in vitro) than to MMP-1, and may therefore lack the musculoskeletal side effects seen with non-specific inhibitors. The aim of the present study was to investigate the safety, tolerability and pharmacokinetics of S-3304 when administered as single and multiple oral doses to healthy male volunteers. MATERIALS AND METHODS: 48 male volunteers received single oral doses ranging from 10 - 800 mg S-3304 or placebo under fasting conditions. At the 200 mg dose level, effects of high-fat diets were studied in a crossover design. In the multiple dose design, 24 male subjects were administered 200 mg, 400 mg or 800 mg S-3304 or placebo b.i.d. after meals for 10 - 17 days. Studies were conducted in a randomized double-blind fashion. Safety assessment was conducted based on blood chemistry, hematology, urinalysis, electrocardiogram and physical examination. Pharmacokinetic parameters were determined for S-3304 and its metabolites. All subjects were enrolled in the studies after obtaining informed consent. RESULTS: Adverse events reported after single dose administration of S-3304 or placebo were all of mild severity. Adverse events reported in the multiple dose treatment with S-3304 or placebo were mostly of mild severity, except for two episodes of moderate headache and two episodes of moderate myalgia. Most commonly reported adverse events in the multiple treatments with S-3304 were headache and somnolence. No clinically significant changes were observed in the clinical laboratory tests, except for reversible elevation of alanine aminotransferase of one subject at 800 mg S-3304 b.i.d. In the single dose administration, Cmax and mean AUC0-infinity linearly increased up to 63,167 ng/ml and 311,960 ng x h/ml at the 800 mg dose level, respectively; tmax and t1/2 ranged from 2 - 3 hours and from 9.5 - 15.5 hours, respectively. High-fat diets reduced Cmax from 21,565 ng/ml to 14,095 ng/ml but did not alter AUC0-infinity. Hydroxylated metabolites were detected in plasma in concentrations less than 1% of S-3304. Less than 1% S-3304 was excreted in urine. The AUC of one dosing interval and Cmax did not change after multiple doses but t1/2 increased from 9.5 - 10.0 hours to 12.5 - 13.5 hours. The 6beta-hydroxycortisol/ cortisol ratio was not changed after multiple doses suggesting no effect on CYP3A4 activity. CONCLUSION: S-3304 demonstrated a good safety profile and good systemic exposure when administered orally up to 800 mg b.i.d. during 10 - 17 days. At the highest dose level of 800 mg b.i.d., it was free of rheumatoid arthritis-like symptoms.

Receptor selectivity of natriuretic peptide family, atrial natriuretic peptide, brain natriuretic peptide, and C-type natriuretic peptide.

To elucidate the ligand-receptor relationship of the natriuretic peptide system, which comprises at least three endogenous ligands, atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP), and three receptors, the ANP-A receptor or guanylate cyclase-A (GC-A), the ANP-B receptor or guanylate cyclase-B (GC-B), and the clearance receptor (C-receptor), we characterized the receptor preparations from human, bovine, and rat tissues and cultured cells with the aid of the binding assay, Northern blot technique, and the cGMP production method. Using these receptor preparations, we examined the binding affinities of ANP, BNP, and CNP for the C-receptor and their potencies for cGMP production via the ANP-A receptor (GC-A) and the ANP-B receptor (GC-B). These analyses revealed the presence of a marked species difference in the receptor selectivity of the natriuretic peptide family, especially among BNPs. Therefore, we investigated the receptor selectivity of the natriuretic peptide family using the homologous assay system with endogenous ligands and receptors of the same species. The rank order of binding affinity for the C-receptor was ANP greater than CNP greater than BNP in both humans and rats. The rank order of potency for cGMP production via the ANP-A receptor (GC-A) was ANP greater than or equal to BNP much greater than CNP, but that via the ANP-B receptor (GC-B) was CNP greater than ANP greater than or equal to BNP. These findings on the receptor selectivity of the natriuretic peptide family provide a new insight into the understanding of the physiological and clinical implications of the natriuretic peptide system.

Rat brain natriuretic peptide. Isolation from rat heart and tissue distribution.

We have isolated a cardiac natriuretic peptide of 5,000 d from atrial tissues from 500 rats and determined its amino acid sequence. The 5,000 d atrial natriuretic factor was elucidated to be a 45 amino acid peptide with the sequence of S-Q-D-S-A-F-R-I-Q-E-R-L-R-N-S-K-M- A-H-S-S-S-C-F-G-Q-K-I-D-R-I-G-A-V-S-R-L-G-C-D-G-L-R-L-F by sequencing the native peptide and its lysyl endopeptidase digests. The sequence of this peptide was identical to the amino acid sequence (51-95) of the rat brain natriuretic peptide precursor deduced from the complementary DNA (cDNA) sequence. The cardiac natriuretic peptide with a molecular weight of 5,000, or rat brain natriuretic peptide, was identified as the major storage form and as the sole secretory form derived from the brain natriuretic peptide precursor in the rat heart. The rat brain natriuretic peptide level in the atrium was 3.68 +/- 0.61 micrograms/g, which represents about 4% of that of atrial natriuretic factor. Rat brain natriuretic peptide was also detected in the ventricle. The ratio of brain natriuretic peptide to atrial natriuretic peptide in the ventricle was approximately 30% and much higher than that in the atrium. Rat brain natriuretic peptide, however, was not detectable in the brain. We conclude that the 5,000 d cardiac natriuretic peptide is rat brain natriuretic peptide with 45 amino acids derived from the brain natriuretic peptide precursor and is secreted from the rat heart as a novel cardiac hormone.

A dicarba analog of beta-atrial natriuretic peptide (beta-ANP) inhibits guanosine 3',5'-cyclic monophosphate production induced by alpha-ANP in cultured rat vascular smooth muscle cells.

The synthesis and biological properties are described of [Asu7,23']-beta-ANP-(7-28) (Asu, L-alpha-aminosuberic acid), a dicarba analog of beta-atrial natriuretic peptide (beta-ANP, an antiparallel dimer of human alpha-ANP with the chains linked by 7-23' and 7'-23 disulfide bonds). This Asu-analog (referred to as analog III) displaced 125I-alpha-ANP specifically bound to cultured rat vascular smooth muscle cells (VSMC) with an apparent Ki of 2.1 x 10(-8) M, but did not stimulate formation of intracellular cGMP at 10(-8) -10(-5) M. Analog III inhibited the alpha-ANP-stimulated cGMP production in VSMC competitively with a pA2 value of 7.45 and behaved as an antagonist of alpha-ANP in rat aorta smooth muscle relaxation. In addition, beta-ANP was also shown to inhibit the alpha-ANP-induced cGMP production in a dose-dependent manner. The mechanism of action of beta-ANP is also discussed.

1,2-Diacylglycerol hydroperoxides induce the generation and release of superoxide anion from human polymorphonuclear leukocytes.

We examined the effect of 1-palmitoyl-2-linoleoylglycerol (PLG), PLG hydroxide (PLG-OH), and PLG hydroperoxide (PLG-OOH) on the release of superoxide anion from human PMNs monitored by the chemiluminescence generated by the superoxide anion-sensitive reagent, 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo[1,2-a]pyrazin++ +-3-one (MCLA). PLG-OOH at low micromolar concentrations stimulated human PMNs whereas PLG and PLG-OH did not. 1,3-Dilinoleoylglycerol hydroperoxide, 1-palmitoyl-2-linoleoylphosphatidylcholine hydroperoxide, and linoleic acid hydroperoxide were much less efficient in stimulating human PMNs than PLG-OOH. The PKC inhibitors, chelerythrine chloride and staurosporine, inhibited the stimulation of PMNs. Possible pathophysiological role of 1,2-diacylglycerol hydroperoxides is discussed.

Useful 1O2 (1delta g) generator, 3-(4'-methyl-1'-naphthyl)-propionic acid, 1',4'-endoperoxide (NEPO), for dioxygenation of squalence (a skin surface lipid) in an organic solvent and bacterial killing in aqueous medium.

3-(4'-Methyl-1'-naphthyl)-propionic acid, 1',4'-endoperoxide (NEPO) provides singlet state of oxygen (1O2, 1delta g) at 37 degrees C in sodium phosphate buffer (pH 7.2), acetate buffer (pH 4.5), methanol or chloroform, through the retro-Diels-Alder reaction. The total amount of 1O2 generated by NEPO was calculated using the following equation: [1O2]= [NEPO]0[1-exp(-kt)], where [1O2], [NEPO]0 and k are the total amount of 1O2 produced during the time t, initial concentration of NEPO and the first-order reaction rate constant, respectively. When squalene was exposed to 1O2 which was generated thermolytically from NEPO, it was oxidized to three hydroperoxides, mono-, di- and tri-hydroperoxides, in amounts proportional to the dose of NEPO. The oxidizability of squalene was much more extensive compared with unsaturated phospholipids. Additionally, when wild-type E. coli and lycopene-producing mutant E. coli were exposed to NEPO-derived 1O2, there was significant loss of viability of wild-type E. coli but no significant loss of viability in lycopene-producing strain, suggesting that lycopene by scavenging 1O2 protected E. coli against 1O2 toxicity.

Inactivation of bacterial respiratory chain enzymes by singlet oxygen.

To distinguish the bactericidal action of singlet oxygen (1O2) from hypohalous acids, wild-type and lycopene transformant E. coli strains were exposed to each of the oxidants and then bacterial viability was investigated. 1O2 was generated by chemical and enzymatic systems at pH 4.5. ExpoSure of wild-type E. coli to 1O2 caused a significant loss of E. coli viability due to inactivation of membrane respiratory chain enzymes by 1O2. This action of 1O2 could be attenuated by lycopene in the bacterial cell membrane. In the lycopene transformant strain of E. coli, inactivation of NADH oxidase and succinate oxidase by hypohalous acids were significantly suppressed, but E. coli viability was unaffected. Based on these findings, we suggest that phagocytic leukocytes produce 1O2 as a major bactericidal oxidant in the phagosome.

Synthesis and biological properties of two dimeric forms of human alpha-atrial natriuretic peptide.

Two dimeric forms of human alpha-atrial natriuretic peptide (alpha-ANP) were synthesized by solution methods and compared with monomeric alpha-ANP in terms of some biological and immunochemical properties. The parallel form (beta'-ANP) and the antiparallel form (beta-ANP) were equipotent in smooth muscle relaxant activity in isolated rat aorta and their ED50 values were estimated to be 1.7 X 10(-8) M and 1.6 X 10(-8) M, respectively. Diuretic and natriuretic responses induced by beta-ANP and beta'-ANP anesthetized rats were equally less potent but exhibited a significantly longer duration than those induced by alpha-ANP. beta-ANP and beta'-ANP possessed immunoreactivities of 60-100% and 50-90% (alpha-ANP, 100% on a molar basis), respectively, with three different antisera raised against alpha-ANP-related peptides.

Isolation and sequence determination of human brain natriuretic peptide in human atrium.

We isolated human brain natriuretic peptide (human BNP) from the human atrium. Sequence analysis has revealed that it is a 32-amino-acid peptide with the sequence S-P-K-M-V-Q-G-S-G-C-F-G-R-K-M-D-R-I-S-S-S-S-G-L-G-C-K-V-L-R-R-H, which is identical to the C-terminal sequence (77-108) of the human BNP precursor deduced from the cDNA sequence. The sequence of human BNP (77-108) is preceded by Pro75-Arg76 in the human BNP precursor, which is the same processing signal as Pro97-Arg98 of the precursor of atrial natriuretic peptide (ANP). The processing of the BNP precursor occurs in the cardiocyte, although that of the ANP precursor in the cardiocyte is unclear at present.

Gas6 rescues cortical neurons from amyloid beta protein-induced apoptosis.

Gas6, a product of the growth-arrest-specific gene 6, protects neurons from serum deprivation-induced apoptosis. Neuronal apoptosis is also caused by amyloid beta protein (Abeta), whose accumulation in the brain is a characteristic feature of Alzheimer's disease. Abeta induces Ca(2+) influx via L-type voltage-dependent calcium channels (L-VSCCs), leading to its neurotoxicity. In the present study, we investigated effects of Gas6 on Abeta-induced cell death in primary cultures of rat cortical neurons. Abeta caused neuronal cell death in a concentration- and time-dependent manner. Gas6 significantly prevented neurons from Abeta-induced cell death. Gas6 ameliorated Abeta-induced apoptotic features such as the condensation of chromatin and the fragmentation of DNA. Prior to cell death, Abeta increased influx of Ca(2+) into neurons through L-VSCCs. Gas6 significantly inhibited the Abeta-induced Ca(2+) influx. The inhibitor of L-VSCCs also suppressed Abeta-induced neuronal cell death. The present cortical cultures contained few non-neuronal cells, indicating that Gas6 affected the survival of neurons directly, but not indirectly via non-neuronal cells. In conclusion, we demonstrate that Gas6 rescues cortical neurons from Abeta-induced apoptosis. Furthermore, the present study indicates that inhibition of L-VSCC contributes to the neuroprotective effect of Gas6.