ATG-101 Is a Tetravalent PD-L1×4-1BB Bispecific Antibody That Stimulates Antitumor Immunity through PD-L1 Blockade and PD-L1-Directed 4-1BB Activation.

Immune checkpoint inhibitors (ICI) have transformed cancer treatment. However, only a minority of patients achieve a profound response. Many patients are innately resistant while others acquire resistance to ICIs. Furthermore, hepatotoxicity and suboptimal efficacy have hampered the clinical development of agonists of 4-1BB, a promising immune-stimulating target. To effectively target 4-1BB and treat diseases resistant to ICIs, we engineered ATG-101, a tetravalent "2+2″ PD-L1×4-1BB bispecific antibody. ATG-101 bound PD-L1 and 4-1BB concurrently, with a greater affinity for PD-L1, and potently activated 4-1BB+ T cells when cross-linked with PD-L1-positive cells. ATG-101 activated exhausted T cells upon PD-L1 binding, indicating a possible role in reversing T-cell dysfunction. ATG-101 displayed potent antitumor activity in numerous in vivo tumor models, including those resistant or refractory to ICIs. ATG-101 greatly increased the proliferation of CD8+ T cells, the infiltration of effector memory T cells, and the ratio of CD8+ T/regulatory T cells in the tumor microenvironment (TME), rendering an immunologically "cold" tumor "hot." Comprehensive characterization of the TME after ATG-101 treatment using single-cell RNA sequencing further revealed an altered immune landscape that reflected increased antitumor immunity. ATG-101 was well tolerated and did not induce hepatotoxicity in non-human primates. According to computational semimechanistic pharmacology modeling, 4-1BB/ATG-101/PD-L1 trimer formation and PD-L1 receptor occupancy were both maximized at around 2 mg/kg of ATG-101, providing guidance regarding the optimal biological dose for clinical trials. In summary, by localizing to PD-L1-rich microenvironments and activating 4-1BB+ immune cells in a PD-L1 cross-linking-dependent manner, ATG-101 safely inhibits growth of ICI resistant and refractory tumors. SIGNIFICANCE: The tetravalent PD-L1×4-1BB bispecific antibody ATG-101 activates 4-1BB+ T cells in a PD-L1 cross-linking-dependent manner, minimizing the hepatotoxicity of existing 4-1BB agonists and suppressing growth of ICI-resistant tumors. See related commentary by Ha et al., p. 1546.

Population Pharmacokinetics and Exposure Response Assessment of CC-292, a Potent BTK Inhibitor, in Patients With Chronic Lymphocytic Leukemia.

CC-292, a potent Bruton tyrosine kinase inhibitor, is under development for the treatment of B-cell malignancies. An analysis was performed to develop a population pharmacokinetic model of CC-292 and assess the influence of demographics and disease-related covariates on CC-292 exposure and to assess the exposure-response (overall response rate) relationship in patients with chronic lymphocytic leukemia. Population pharmacokinetic analysis was based on a 2-compartment base model conducted in NONMEM. Categorical exposure-response analysis was performed using logistic regression in SAS. The population pharmacokinetic analysis results indicated that CC-292 pharmacokinetic disposition is similar between healthy subjects and patients. CC-292 showed a larger central compartment volume of distribution than the peripheral compartment volume of distribution (158 L and 72 L, respectively) and a faster clearance than intercompartmental clearance (134 L/h and 18.7 L/h, respectively), indicating that for CC-292, clearance from blood occurs faster than distribution into deep tissues and organs. CC-292 clearance is not affected by demographics or baseline clinical lab factors, except for sex. Although sex significantly reduced variation of apparent clearance, the sex effect on apparent clearance is unlikely to be clinically relevant. The exposure-response analysis suggested that higher drug exposure is linearly correlated with higher overall response rate. A twice-daily dose regimen showed higher overall response rate as compared to once-daily dosing, consistent with a threshold concentration of approximately 300 ng/mL, above which the probability of overall response rate significantly increases.

Long-term use of lenalidomide and low-dose dexamethasone in Chinese patients with relapsed/refractory multiple myeloma: MM-024 Extended Access Program.

BACKGROUND: The efficacy and safety of lenalidomide plus low-dose dexamethasone (Rd) in Chinese patients with relapsed/refractory multiple myeloma (RRMM) was demonstrated in a phase 2, multicenter trial (MM-021). MM-024 was an Extended Access Program (EAP) that allowed responding patients in the MM-021 trial to continue to receive Rd, and to provide additional safety and efficacy data with longer follow-up. METHODS: Chinese patients with RRMM who completed ≥ 1 year of Rd therapy in MM-021 and who remained progression-free under Rd entered the Treatment Phase of the MM-024 EAP, continuing Rd at the same dose and schedule. Patients in MM-021 who discontinued Rd treatment or progressed were allowed to enroll in the Safety Follow-Up Phase of the MM-024 EAP. Safety data, including the incidence of second primary malignancies (SPMs), were collected for ≥ 5 years from the time the last on-study patient enrolled in the MM-021 trial (primary end point). Efficacy outcomes (time to progression [TTP], progression-free survival [PFS], and overall survival [OS]) were secondary end points. RESULTS: Median follow-up was 38.4 months for the safety population (n = 80) and 43.3 months for the treatment cohort (n = 41). In the safety population, Grade 3-4 adverse events (AEs) occurred in 60.0 % of patients; the most common grade 3-4 AEs were neutropenia (20.0%), decreased neutrophil count (13.8%), and anemia (11.3%). There was no evidence of cumulative toxicity, and no patients discontinued Rd due to AEs; 2 patients had SPMs. In the treatment cohort, median duration of response was 35.1 months, median TTP was 36.9 months, and median PFS was 36.0 months; median OS was not reached due to the low number of deaths (n = 5). CONCLUSION: Long-term treatment with Rd has a predictable and manageable safety profile and provides sustained efficacy in Chinese patients with RRMM. TRIAL REGISTRATION: China State Food and Drug Administration (SFDA) registration (CTA reference numbers: 209L10808; 209L10809; 209L10810; and 209L10811) and ClinicalTrials.gov Identifier: NCT02348528. First received January 23, 2015; last updated November 12, 2015; last verified November 2015; study start date September 2012.

Safety and efficacy of different lenalidomide starting doses in patients with relapsed or refractory chronic lymphocytic leukemia: results of an international multicenter double-blinded randomized phase II trial.

The objective of this study was to evaluate the safety and efficacy of different lenalidomide starting doses in patients with relapsed/refractory chronic lymphocytic leukemia (CLL). CLL patients were randomized to receive lenalidomide at initial doses of 5, 10, or 15 mg/d (N = 103). Doses were escalated by 5 mg every 28-d up to a maximum of 25 mg/d; dose reductions in up to 5 mg decrements were permitted. The most common grade ≥3 adverse events (AEs) were neutropenia and thrombocytopenia. Ten patients died during therapy (four deaths considered as related to lenalidomide); 12 patients experienced second primary malignancies. The most common cause for treatment discontinuation was AEs. Overall response rates were similar across arms. Progression-free survival and overall survival rates were longer in patients who escalated treatment (to 15 or 20 mg/d) versus those who did not. Lower starting doses allowed subsequent dose escalation of lenalidomide while maintaining an acceptable tolerability profile in patients with relapsed/refractory CLL.

Ornithine-δ-Aminotransferase Inhibits Neurogenesis During Xenopus Embryonic Development.

PURPOSE: In humans, deficiency of ornithine-δ-aminotransferase (OAT) results in progressive degeneration of the neural retina (gyrate atrophy) with blindness in the fourth decade. In this study, we used the Xenopus embryonic developmental model to study functions of the OAT gene on embryonic development. METHODS: We cloned and sequenced full-length OAT cDNA from Xenopus oocytes (X-OAT) and determined X-OAT expression in various developmental stages of Xenopus embryos and in a variety of adult tissues. The phenotype, gene expression of neural developmental markers, and enzymatic activity were detected by gain-of-function and loss-of-function manipulations. RESULTS: We showed that X-OAT is essential for Xenopus embryonic development, and overexpression of X-OAT produces a ventralized phenotype characterized by a small head, lack of axial structure, and defective expression of neural developmental markers. Using X-OAT mutants based on mutations identified in humans, we found that substitution of both Arg 180 and Leu 402 abrogated both X-OAT enzymatic activity and ability to modulate the developmental phenotype. Neurogenesis is inhibited by X-OAT during Xenopus embryonic development. CONCLUSIONS: Neurogenesis is inhibited by X-OAT during Xenopus embryonic development, but it is essential for Xenopus embryonic development. The Arg 180 and Leu 402 are crucial for these effects of the OAT molecule in development.

Lenalidomide plus low-dose dexamethasone in Chinese patients with relapsed or refractory multiple myeloma and renal impairment.

Lower starting doses of lenalidomide (LEN) are recommended for patients with renal impairment (RI). In the present study, we conducted a subgroup analysis of the MM-021 registration trial to investigate the efficacy and safety of LEN plus low-dose dexamethasone (LoDEX) in Chinese patients with advanced relapsed or refractory multiple myeloma (RRMM) based on levels of RI. Patients received LEN+LoDEX until disease progression or discontinuation. Patients were divided according to RI: no/mild [creatinine clearance (CrCl) ≥60 mL/min, n = 131], moderate (CrCl ≥30 to <60 mL/min, n = 54), and severe (CrCl <30 mL/min, n = 14). LEN starting dose was 25 mg/day on days 1-21, adjusted for baseline renal function. Best overall response rate was 48 %; in patients with no/mild, moderate, or severe RI, response rates were 50, 42, and 42 %, respectively. Median progression-free survival and overall survival were longer in patients with no/mild RI (9.3 and 22.4 months, respectively) versus those with moderate (6.9 and 16.0 months) or severe RI (4.8 and 11.1 months). LEN+LoDEX was well tolerated, although incidences of grade 3-4 neutropenia, anemia, and thrombocytopenia were higher in patients with severe RI. In Chinese patients with advanced RRMM and RI, adjusting the starting dose of LEN according to renal function did not compromise the efficacy or safety of LEN+LoDEX.

Factors that influence health-related quality of life in newly diagnosed patients with multiple myeloma aged ≥ 65 years treated with melphalan, prednisone and lenalidomide followed by lenalidomide maintenance: results of a randomized trial.

In the MM-015 trial, melphalan-prednisone-lenalidomide followed by lenalidomide maintenance (MPR-R) significantly prolonged progression-free survival versus melphalan-prednisone (MP) in newly diagnosed patients with multiple myeloma aged ≥ 65 years. Health-related quality of life (HRQoL), a secondary endpoint of MM-015, was also improved with MPR-R. This sub-analysis evaluated the impact of individual predictive factors on HRQoL. Patients completed HRQoL questionnaires at baseline, every third cycle and at progressive disease (PD)/treatment discontinuation. In a mixed-effects model female gender, advanced age and PD negatively affected HRQoL while better treatment responses showed positive effects. Compared to PD, HRQoL during MPR-R treatment was statistically significantly better in two of six preselected domains both of which were also clinically meaningful. HRQoL scores at end of treatment were all either improved or not statistically significantly different versus baseline. In conclusion, continuous treatment with MPR-R, which delays PD, appears to be associated with clinically meaningful improvements in HRQoL.

A multicenter, open-label, phase 2 study of lenalidomide plus low-dose dexamethasone in Chinese patients with relapsed/refractory multiple myeloma: the MM-021 trial.

BACKGROUND: There is an unmet need for treatment options in Chinese patients with relapsed or refractory multiple myeloma (RRMM). Lenalidomide plus low-dose dexamethasone is effective and generally well tolerated in Caucasian RRMM patients, but no previous study has evaluated this regimen in Chinese RRMM patients. METHODS: MM-021 is a phase 2, multicenter, single-arm open-label registration trial conducted to assess the efficacy, safety, and pharmacokinetics of lenalidomide plus low-dose dexamethasone in Chinese patients with RRMM. Patients with ≥1 prior antimyeloma therapy received lenalidomide plus low-dose dexamethasone until disease progression or discontinuation. Follow-up of surviving patients continued for ≥1 year after enrollment. The lenalidomide dose was 25 mg/day, and was adjusted according to baseline renal function. Most patients had advanced disease (85.6% had Durie-Salmon stage III) and were heavily pretreated (56.7% had received ≥4 prior regimens; 69.5% prior thalidomide and 63.1% prior bortezomib); 5.3% had immunoglobulin D (IgD) disease. RESULTS: The safety population comprised 199 eligible patients. In the efficacy population (n = 187), the disease control rate (at least stable disease) was 94.7%, and the overall response rate (at least partial response) was 47.6%. High response rates were also achieved in patients who had renal impairment and in those with IgD disease. After a median study follow-up of 15.2 months, the median response duration was 8.8 months (range, 0.4-18.8 months) and median progression-free survival was 8.3 months (95% CI 6.5-9.8). The most common grade 3-4 adverse events (AEs) were anemia (26.1%), neutropenia (25.1%), thrombocytopenia (14.6%), pneumonia (13.1%), leukopenia (9.5%), and decreased neutrophil count (8.5%). AEs led to lenalidomide dose reduction and/or interruption in 40.2% of patients, and treatment discontinuation in about 9% of patients. The pharmacokinetic profile of lenalidomide was similar to that reported in Caucasian and Japanese patients. CONCLUSIONS: Lenalidomide plus low-dose dexamethasone was associated with a high response rate and acceptable safety profile in heavily pretreated Chinese patients with RRMM, including those with renal impairment and IgD subtype. These findings highlight the clinical potential of this regimen in Chinese RRMM patients who have exhausted current treatment options. TRIAL REGISTRATION: China State Food and Drug Administration (SFDA) registration (CTA reference numbers: 209 L10808; 209 L10809; 209 L10810; and 209 L10811) and ClinicalTrials.gov identifier: NCT01593410.

Lenalidomide, melphalan, and prednisone, followed by lenalidomide maintenance, improves health-related quality of life in newly diagnosed multiple myeloma patients aged 65 years or older: results of a randomized phase III trial.

The MM-015 trial assessed the effect of lenalidomide-based therapy on health-related quality of life. Patients (n=459) with newly diagnosed multiple myeloma aged 65 years or over were randomized 1:1:1 to nine 4-week cycles of lenalidomide, melphalan, and prednisone, followed by lenalidomide maintenance; or lenalidomide, melphalan, and prednisone, or melphalan and prednisone, with no maintenance therapy. Patients completed health-related quality of life questionnaires at baseline, after every third treatment cycle, and at treatment end. Health-related quality of life improved in all treatment groups during induction therapy. Patients receiving lenalidomide maintenance had the most pronounced improvements, Global Health Status/Quality of Life (P<0.05), Physical Functioning (P<0.01), and Side Effects of Treatment (P<0.05) out of 6 pre-selected health-related quality of life domains. More patients receiving lenalidomide maintenance achieved minimal important differences (P<0.05 for Physical Functioning). Therefore, lenalidomide, melphalan, and prednisone, followed by lenalidomide maintenance, improves health-related quality of life in patients with newly diagnosed multiple myeloma. (Clinicaltrials.gov identifier NCT00405756).

Continuous lenalidomide treatment for newly diagnosed multiple myeloma.

BACKGROUND: Lenalidomide has tumoricidal and immunomodulatory activity against multiple myeloma. This double-blind, multicenter, randomized study compared melphalan-prednisone-lenalidomide induction followed by lenalidomide maintenance (MPR-R) with melphalan-prednisone-lenalidomide (MPR) or melphalan-prednisone (MP) followed by placebo in patients 65 years of age or older with newly diagnosed multiple myeloma. METHODS: We randomly assigned patients who were ineligible for transplantation to receive MPR-R (nine 4-week cycles of MPR followed by lenalidomide maintenance therapy until a relapse or disease progression occurred [152 patients]) or to receive MPR (153 patients) or MP (154 patients) without maintenance therapy. The primary end point was progression-free survival. RESULTS: The median follow-up period was 30 months. The median progression-free survival was significantly longer with MPR-R (31 months) than with MPR (14 months; hazard ratio, 0.49; P<0.001) or MP (13 months; hazard ratio, 0.40; P<0.001). Response rates were superior with MPR-R and MPR (77% and 68%, respectively, vs. 50% with MP; P<0.001 and P=0.002, respectively, for the comparison with MP). The progression-free survival benefit associated with MPR-R was noted in patients 65 to 75 years of age but not in those older than 75 years of age (P=0.001 for treatment-by-age interaction). After induction therapy, a landmark analysis showed a 66% reduction in the rate of progression with MPR-R (hazard ratio for the comparison with MPR, 0.34; P<0.001) that was age-independent. During induction therapy, the most frequent adverse events were hematologic; grade 4 neutropenia was reported in 35%, 32%, and 8% of the patients in the MPR-R, MPR, and MP groups, respectively. The 3-year rate of second primary tumors was 7% with MPR-R, 7% with MPR, and 3% with MP. CONCLUSIONS: MPR-R significantly prolonged progression-free survival in patients with newly diagnosed multiple myeloma who were ineligible for transplantation, with the greatest benefit observed in patients 65 to 75 years of age. (Funded by Celgene; MM-015 ClinicalTrials.gov number, NCT00405756.).

(6,7-Dimethoxy-2,4-dihydroindeno[1,2-c]pyrazol-3-yl)phenylamines: platelet-derived growth factor receptor tyrosine kinase inhibitors with broad antiproliferative activity against tumor cells.

A series of (6,7-dimethoxy-2,4-dihydroindeno[1,2-c]pyrazol-3-yl)phenylamines has been optimized to preserve both potent kinase inhibition activity against the angiogenesis target, the receptor tyrosine kinase of Platelet-Derived Growth Factor-BB (PDGF-BB), and to improve the broad tumor cell antiproliferative activity of these compounds. This series culminates in the discovery of 17 (JNJ-10198409), a compound with anti-PDGFR-beta kinase activity (IC(50)=0.0042 microM) and potent antiproliferative activity in six of eight human tumor cell lines (IC(50) < 0.033 microM).

Cloning, expression, and functional characterization of human cyclooxygenase-1 splicing variants: evidence for intron 1 retention.

Recently, a splicing variant of cyclooxygenase (COX)-1, arising via the retention of its intron 1, was identified in canine. It was called COX-3 and was reported to be differentially sensitive to inhibition by various nonsteroidal anti-inflammatory drugs (NSAIDs) as well as acetaminophen (Chandrasekharan et al., 2002). However, the existence of an orthologous splicing variant in human tissues has been questioned due to a reading frame shift and premature termination. In this study, we first confirmed the existence of intron 1-retained COX-1 in certain human tissues at both the mRNA and protein levels. Molecular biology studies revealed that three distinct COX-1 splicing variants exist in human tissues. The most prevalent of these variants, called COX-1b1, arises via retention of the entire 94 base pair (bp) of intron 1, leading to a shift in the reading frame and termination at bp 249. However, the other two variant types, called COX-1b2 and COX-1b3, retain entire intron 1, but they are missing a nucleotide in one of two different positions, thereby encoding predicted full-length and likely COX-active proteins. Functional studies revealed that the COX-1b2 is able to catalyze the synthesis of prostaglandin F2alpha from arachidonic acid with Km and Vmax values of 0.54 microM and 3.07 pmol/mg/min, respectively. However, no significant differential selectivity for inhibition by selected NSAIDs was observed. Accordingly, we conclude that intron 1-retained human COX-1 is not likely to be the therapeutic target of acetaminophen or a candidate of COX-3.

Validation of in vivo pharmacodynamic activity of a novel PDGF receptor tyrosine kinase inhibitor using immunohistochemistry and quantitative image analysis.

With the advent of agents directed against specific molecular targets in drug discovery, it has become imperative to show a compound's cellular impact on the intended biomolecule in vivo. The objective of the present study was to determine if we could develop an assay to validate the in vivo effects of a compound. Hence, we investigated the in vivo pharmacodynamic activity of JNJ-10198409, a relatively selective inhibitor of platelet-derived growth factor receptor tyrosine kinase (PDGF-RTK), in tumor tissues after administering the compound orally in a nude mouse xenograft model of human LoVo colon cancer. We developed a novel assay to quantify the in vivo anti-PDGF-RTK activity of the inhibitor in tumor tissue by determining the phosphorylation status of phospholipase Cgamma1 (PLCgamma1), a key downstream cellular molecule in the PDGF-RTK signaling cascade. We used two antibodies, one specific for the total (phosphorylated and unphosphorylated forms) PLCgamma1 (pan-PLCgamma1) and the other, specific for phosphorylated form of PLCgamma1 (ph-PLCgamma1) to immunohistochemically detect their expression in tumor tissues. Computer-assisted image analysis was then used to directly compare the ratio of ph-PLCgamma1 to pan-PLCgamma1 immunolabeling intensities in serial sections (5 mum) of tumors obtained from vehicle- and JNJ-10198409-treated tumor-bearing mice. Our data showed statistically significant, dose-dependent differences in the ph-PLC/pan-PLC ratio among the four treatment groups (vehicle, 25, 50, and 100 mg/kg b.i.d.). These results confirmed this compound's ability to suppress PDGF-RTK downstream signaling in tumor tissues in vivo. In addition to this specific application of this in vivo validation approach to those targets that use PLCgamma as a downstream signaling partner, these methods may also benefit other drug discovery targets.

Multiplexed RT- PCR for high throughput screening applications.

To increase efficiency of high throughput gene expression profiling, we established a new TaqMan RT-PCR (real-time reverse transcriptase-polymerase chain reaction with internal probes for the quantification of PCR products) method for quantitative mRNA expression analysis. In this procedure, we utilized poly-A mRNA capture plates and validated a multiplexed single tube RT-PCR assay for cell culture applications, including compound testing via gene induction measurement. In the described procedure, all steps including RNA extraction, RT and PCR are performed in the same tube, thus significantly enhancing throughput of this method. Optimization of conditions, including the number of cells necessary for detection of mRNA signal was performed. With a relatively abundant message such as GAPDH, we saw a linear response for all of the concentrations tested, from 10,000 cells to 10 cells. We have also demonstrated multiplexing of different targets within the PCR reactions. In these experiments, we combined VIC-labeled probes for GAPDH with several FAM-labeled probes obtained from Assays On Demand (Applied Biosystems). In the reported experiments, multiplexing did not affect the efficiency of RT-PCR. We also demonstrated the utility of this technology for compound screening applications. The described technology also has the potential to accelerate studies on target and biomarker identification and toxicity assessment in ADMET (absorption, distribution, metabolism, elimination, and toxicity) testing.

Gene expression analysis for high throughput screening applications.

To meet growing needs for high throughput gene expression profiling, we established a new automated high throughput TaqMan RT-PCR method for quantitative mRNA expression analysis. In this method, the Allegro( trade mark ) (Zymark) system conducts all sample tracking and liquid handling steps, and ABI PRISM 7900 HT (Applied Biosystems) is used to conduct real-time determination of the C(t) value when amplification of PCR products is first detected and accumulation of inhibitory PCR products is unlikely to occur. The ABI PRISM 7900 HT Sequence Detection System features a real-time PCR instrument with 384-well-plate compatibility and robotic loading, and continuous wavelength detection, which enables the use of multiple fluorophores in a single reaction. The Allegro System offers an assembly line approach with a modular design that allows reconfiguration of the components to accommodate variations in the assay flow. In the present study, we have established and validated a new automated High Throughput (HT) TaqMan RT-PCR- based method for quantitative mRNA expression analysis. The data demonstrate that HT-Taqman PCR is a powerful tool that can be used for measuring low concentrations of mRNA, and is highly accurate, reproducible, and amenable to high throughput analysis. Results suggest that HT-TaqMan is a reliable method for the quantification of low-expression genes and a powerful tool with HT capability for target identification/validation, structure-activity relationship (SAR) study, compound selection for efficacy studies, and biomarker identification in drug discovery and development.

Matrix metalloproteinase(s) mediate(s) NO-induced dissociation of beta-catenin from membrane bound E-cadherin and formation of nuclear beta-catenin/LEF-1 complex.

Modulation of the adenomatous polyposis coli (APC)-beta-catenin pathway by inflammatory mediators and extracellular matrix may be important in colon carcinogenesis. We have recently shown that nitric oxide (NO) induces the accumulation of cytosolic beta-catenin and subsequent formation of the nuclear beta-catenin/lymphocyte enhancing factor (LEF)-1 complex in conditionally immortalized young mouse colonic epithelial (YAMC) cells. In the present study, we explored the mechanism(s) through which NO exerts its effect on cytosolic beta-catenin accumulation and nuclear beta-catenin/LEF-1 complex formation. We found that NO-induced degradation of the membrane bound E-cadherin at tight junctions. Using an anti-E-cadherin antibody specific for its extracellular domain, we detected a 50kDa degradation fragment of E-cadherin (120 kDa) from the culture medium conditioned by YAMC cells exposed to the NO-releasing drug, NOR-1, for 4 and 24 h. As beta-catenin is normally bound to transmembrane E-cadherin and thus anchored to the cytoskeleton structure, the degradation of E-cadherin induced by NO may cause dissociation of beta-catenin from membrane bound E-cadherin. This was demonstrated by the detection of beta-catenin accumulation in the soluble cytosolic fractions in YAMC after exposure to NO-releasing drugs. Furthermore, the degradation of E-cadherin and the release of beta-catenin to cytosol were accompanied by the formation of nuclear beta-catenin/LEF-1 complex, demonstrating the dissociation of beta-catenin from E-cadherin may be responsible for the activation of beta-catenin/LEF-1 transcription complex. Co-treatment with NO donors and broad-spectrum matrix metalloproteinase (MMP) inhibitors TIMP-1 (100 ng/ml), GM6001 (10 micro M) and GM1489 (10 micro M) abolished the degradation of E-cadherin induced by NO as demonstrated by western blot analysis. These MMP inhibitors also blocked the cytosolic accumulation of beta-catenin and nuclear formation of beta-catenin/LEF-1 complex. The sum effect of MMP inhibitors demonstrated that NO-induced activation of MMP may cause the degradation of E-cadherin and the subsequent dissociation of beta-catenin, thereby contributing to the cytosolic accumulation of beta-catenin and nuclear formation of beta-catenin/LEF-1 complex.