Betaine alleviates spermatogenic cells apoptosis of oligoasthenozoospermia rat model by up-regulating methyltransferases and affecting DNA methylation.

BACKGROUND: Oligoasthenozoospermia is the most common type of semen abnormality in male infertile patients. Betaine (BET) has been proved to have pharmacological effects on improving semen quality. BET also belongs to endogenous physiological active substances in the testis. However, the physiological function of BET in rat testis and its pharmacological mechanism against oligoasthenozoospermia remain unclear. PURPOSE: This research aims to prove the therapeutic effect and potential mechanism of BET on oligoasthenozoospermia rat model induced by Tripterygium wilfordii glycosides (TWGs). METHODS: The oligoasthenozoospermia rat model was established by a continuous gavage of TWGs (60 mg/kg) for 28 days. Negative control group, oligoasthenozoospermia group, positive drug group (levocarnitine, 300 mg/kg), and 200 mg/kg, 400 mg/kg, and 800 mg/kg BET groups were created for exploring the therapeutic effect of BET on the oligoasthenozoospermia rat model. The therapeutic effect was evaluated by HE and TUNEL staining. Immunofluorescence assay of DNMT3A, PIWIL1, PRMT5, SETDB1, BHMT2, and METTL3, methylation capture sequencing, Pi-RNA sequencing, and molecular docking were used to elucidate potential pharmacological mechanisms. RESULTS: It is proved that BET can significantly restore testicular pathological damage induced by TWGs, which also can significantly reverse the apoptosis of spermatogenic cells. The spermatogenic cell protein expression levels of DNMT3A, PIWIL1, PRMT5, SETDB1, BHMT2, and METTL3 significantly decreased in oligoasthenozoospermia group. 400 mg/kg and 800 mg/kg BET groups can significantly increase expression level of the above-mentioned proteins. Methylation capture sequencing showed that BET can significantly increase the 5mC methylation level of Spata, Spag, and Specc spermatogenesis-related genes. Pi-RNA sequencing proved that the above-mentioned genes produce a large number of Pi-RNA under BET intervention. Pi-RNA can form complexes with PIWI proteins to participate in DNA methylation of target genes. Molecular docking indicated that BET may not directly act as substrate for methyltransferase and instead participates in DNA methylation by promoting the methionine cycle and increasing S-adenosylmethionine synthesis. CONCLUSION: BET has a significant therapeutic effect on oligoasthenozoospermia rat model induced by TWPs. The mechanism mainly involves that BET can increase the methylation level of Spata, Specc, and Spag target genes through the PIWI/Pi-RNA pathway and up-regulation of methyltransferases (including DNA methyltransferases and histone methyltransferases).

Dopey2 and Pcdh7 orchestrate the development of embryonic neural stem cells/ progenitors in zebrafish.

DOPEY2 has been shown to be associated with Down syndrome and PCDH7 might be involved in Rett syndrome and MECP2 duplication syndrome. The mechanism how both proteins play roles in these syndromes are largely unknown. Here, we show that Dopey2 and Pcdh7 balance the proliferation and differentiation of neural stem cells and progenitors during embryonic neurogenesis to generate proper size and architecture of zebrafish brains. Dopey2 and Pcdh7 mutually restricted expression of each other in zebrafish embryos. Dopey2 was responsible for the proliferation of neural stem cells/progenitors, whereas Pcdh7 was responsible for the differentiation of neural stem cells/progenitors. Both proteins were shown to orchestrate the proper development and arrangement of neural cells in zebrafish embryonic brains. The results provide an insight into mechanisms to understand how the embryonic brain is constituted and how developmental defects occur in the brains of patients with Down syndrome, Rett syndrome, or MECP2 duplication syndrome.

Solitary fibrous tumor of the central nervous system invading and penetrating the skull: A case report.

Solitary fibrous tumor (SFT) of the central nervous system is a rare spindle cell tumor of mesenchymal origin. The present study reports the case of a 44-year-old male patient with SFT. Magnetic resonance imaging demonstrated that the majority of the intracranial tumors exhibited uneven low signals on T1-weighted imaging (T1WI) and low mixed signals on T2WI, and there was an enhancement on enhanced scanning. Furthermore, the distal part of the left occipital lobe exhibited hypersignals on T1WI and T2WI, and this was significantly enhanced following enhanced scanning. The lower part of the scalp exhibited low signals on T1WI and high signals on T2WI, and there was no notable enhancement following enhanced scanning. Magnetic resonance spectroscopy demonstrated an elevated choline/creatine peak in the solid part of the tumor. Under the microscope, the tumor exhibited characteristic 'staghorn-shaped' blood vessels. As SFT is difficult to differentially diagnose via imaging, immunohistochemical analysis of CD34, vimentin and signal transducer and activator of transcription 6 was performed for the definitive diagnosis of SFT. Of note, surgical resection was the preferred treatment for SFT; however, due to the rarity of the tumor, subsequent adjuvant therapy and prognosis require further investigation.

Discovery of 1'-(1-phenylcyclopropane-carbonyl)-3H-spiro[isobenzofuran-1,3'-pyrrolidin]-3-one as a novel steroid mimetic scaffold for the potent and tissue-specific inhibition of 11ß-HSD1 using a scaffold-hopping approach.

11ß-hydroxysteroid dehydrogenase 1 (11ß-HSD1) has been identified as the primary enzyme responsible for the activation of hepatic cortisone to cortisol in specific peripheral tissues resulting in the concomitant antagonism of insulin action within these tissues. Dysregulation of 11ß-HSD1, particularly in adipose tissues, has been associated with metabolic syndrome and type 2 diabetes mellitus. Therefore, inhibition of 11ß-HSD1 with a small nonsteroidal molecule is therapeutically desirable. Implementation of a scaffold-hopping approach revealed a three-point pharmacophore for 11ß-HSD1 that was utilized to design a steroid mimetic scaffold. Reiterative optimization provided valuable insight into the bioactive conformation of our novel scaffold and led to the discovery of INCB13739. Clinical evaluation of INCB13739 confirmed for the first time that tissue-specific inhibition of 11ß-HSD1 in patients with type 2 diabetes mellitus was efficacious in controlling glucose levels and reducing cardiovascular risk factors.

Metabolic profiling and pharmacokinetic studies of sinapine thiocyanate by UHPLC-Q/TOF-MS and UHPLC-MS/MS.

Sinapine thiocyanate (ST) is an index component and pharmacological active component of Semen Sinapis and Semen Raphani, and it is widely used to relieving cough and asthma. This study aimed to obtain the metabolic and pharmacokinetic characterization of ST. The metabolic profiles of ST were obtained from rat plasma, urine, and feces via ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UHPLC-Q/TOF-MS). Thirteen metabolites were structurally identified, and the proposed metabolic pathways of ST included deamination, demethylation, hydrogenation, dehydration, and extensive conjugation, including glucuronidation and sulfonation. ST was selected as the plasma marker for the pharmacokinetic study. A simple and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed for the quantitation of ST in rat plasma. The linear range of ST was 0.1-500 ng/mL (R2 = 0.9976), and the lowest limit of quantification was 0.1 ng/mL. The intra-precision and inter-precision of the assay were 1.31-5.12% and 2.72-7.66%, and the accuracy (RE%) ranged from - 4.88% to 3.82% and - 3.47% to 6.18%. The extraction recovery, matrix effect, and stability of ST were within acceptable limits. The established method was validated and successfully applied to the pharmacokinetic study of ST. For pharmacokinetic experiments, the male Sprague-Dawley rats were administrated with ST solution intravenously (2 mg/kg) or orally (100 mg/kg). The oral absolute bioavailability of ST was calculated as 1.84%, and the apparent volume of distribution of intravenous and intragastric administrations were 107.51 ± 21.16 L/kg and 78.60 ± 14.44 L/kg, respectively. The maximum plasma concentration was 47.82 ± 18.77 nM, and the time to maximum peak was 88.74 ± 20.08 min for the intragastric dosing group. According to the pharmacokinetic and metabolic profiling results, metabolites with high abundance of ST in bio-fluids would be the next object in tissue distribution and pharmacodynamic study.

Biotransformation patterns of dictamnine in vitro/in vivo and its relative molecular mechanism of dictamnine-induced acute liver injury in mice.

Dictamnine (DIC), a typical furan-quinoline alkaloid, has a wide range of pharmacological and toxicological effects, such as anti-bacterial, antifungal, anti-cancer, and hepatoxicity. But the molecular mechanism of DIC-induced hepatoxicity in mice remains unclear. This study aimed to clarify the biotransformation patterns of DIC in vitro/in vivo and the relative molecular mechanism of DIC-induced hepatoxicity in mice. All metabolites of DIC were identified by comparing the blank and drug-containing urine, feces, plasma, and liver samples. The structure of epoxide intermediate derived from DIC was confirmed by trapping assay. Oxidative stress injury and inflammation have been confirmed to be involved in the toxicological process of DIC-induced hepatoxicity in mice by detecting the relative biochemical indexes. The results will help to develop a deeper understanding about the biotransformation patterns of DIC, structure of the epoxide intermediate, and the molecular mechanism of DIC-induced hepatoxicity in mice.

Pharmacokinetic studies of ginsenosides Rk1 and Rg5 in rats by UFLC-MS/MS.

A rapid ultra-fast liquid chromatography tandem mass spectrometry method was developed and validated to determine ginsenosides Rk1 and Rg5, a pair of isomers, in rat plasma, which was successfully applied to their pharmacokinetic studies. Two ginsenosides were given to male Sprague-Dawley rats via intragastrical and intravenous routes, respectively, and the impact of double bond position on the pharmacokinetic features of the two ginsenosides was elucidated in rats. Ginsenoside Rg3 was used as internal standard and ethyl acetate was applied to extract analytes and internal standard. Chromatographic separation was carried out on a reverse-phase UPLC HSS T3 column (100 × 2.1 mm, 1.8 µm). The flow rate was set to 0.4 ml/min. The fragmentation transition was m/z 765.4 → m/z 101.1 for two ginsenosides. The mobile phases were composed of 0.1% formic acid aqueous solution and acetonitrile. The linear range was 2-1,000 ng/ml for the two ginsenosides. Intra- and inter-day precisions were <11.67%, and accuracy fluctuated from -7.44 to 6.78%. The extraction recovery, matrix effect and stability were within acceptable levels. After treatment with ginsenosides Rk1 and Rg5, some differences were found in their pharmacokinetic profiles in rats. The maximum plasma drug concentration and the area under the plasma drug concentration-time curve of ginsenoside Rg5 were about 5 times bigger than those of ginsenoside Rk1 after oral administration, and 3 times higher after intravenous administration. The oral bioavailabilities of ginsenosides Rk1 and Rg5 were 0.67 and 0.97%, respectively. The results indicated that ∆20(22) -ginsenosides showed better pharmacokinetic features than ∆20(21) -ginsenosides with the same glycosylation.

Dynamic changes in chemical compositions and anti-acetylcholinesterase activity associated with steaming process of stem-leaf saponins of Panax notoginseng.

Stem-leaf saponins (SLSs), the total saponins from aerial part of P. notoginseng, are by-products of notoginseng, a famous traditional Chinese medicine. SLSs have been used as a health functional food in China, but its mild effects limited clinical applications in diseases. Inspired by steaming of notoginseng to enhance its pharmacological activity, a steaming protocol was developed to treat SLSs. SLSs were steamed at 100, 120, and 140°C for 1, 2, 3, and 4 h, respectively. The ultra-performance liquid chromatography coupled with quadrupole time-of-flight MS and ultra-performance liquid chromatography-tandem triple quadrupole mass spectrometry were applied to analyze the dynamic changes in chemical compositions. The anti-acetylcholinesterase activity of steamed SLS were assessed in vitro by directly determining the metabolic product of acetylcholine/choline. The components of SLSs were significantly changed by steaming. A total of 117 saponins and aglycones were characterized, and 35 of them were newly generated. The anti-acetylcholinesterase activity of steamed SLSs gradually increased with the extension of steamed time and the increase of steamed temperature and reached the maximum after 140°C for 3 h. Furthermore, ginsenosides Rk1 and Rg5, the main components of steamed SLSs, showed dose-dependent anti-acetylcholinesterase activities with half maximal inhibitory concentration (IC50 ) values of 26.88 ± 0.53 µm and 22.41 ± 1.31 µm that were only 1.8- and 1.5-fold higher than that of donepezil with IC50 values of 14.93 ± 4.17 µM, respectively.

Metabolites identification and reversible interconversion of chelerythrine and dihydrochelerythrine in vitro/in vivo in rats using ultra-performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight tandem mass spectrometry.

Chelerythrine (CHE) and dihydrochelerythrine (DHCHE), two typical benzophenanthridine alkaloids, have a wide range of pharmacological activities, such as antibacterial, anti-tumour and antiparasitic activities. To date, the biological activities of CHE and DHCHE are well reported, but the biotransformation of CHE and DHCHE in vivo remains unknown. This study aims to clarify the metabolic pathway of CHE and DHCHE in rat liver microsomes (RLMs) in vitro and in vivo. An ultra-performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC/ESI-QTOF-MS) method was developed for metabolites identification of CHE and DHCHE. The urine, feces, bile, and plasma samples and RLMs samples were collected for analyzing the biotransformation pathway of CHE and DHCHE. The result showed that there is a phenomenon of mutual reversible interconversion between CHE and DHCHE in vivo and in vitro. The other biotransformation pathways of CHE and DHCHE including demethylation, hydroxylation, methylene dioxy cycle opening, and glucuronidation mainly occurred in the side chain of benzophenanthridine parent structure. Twenty-five phase I and eight phase II metabolites of CHE, twenty-two phase I and eight phase II metabolites of DHCHE were detected. The results will help to develop a deeper understanding of CHE and DHCHE in vivo process and provide some references for the biotransformation research of other benzophenanthridine alkaloids.

[Treatment efficacy of Solitaire stent- and LVIS stent-assisted coil embolization for intracranial wide-neck carotid aneurysm].

OBJECTIVE: To compare the safety, efficacy and complications of LVIS stent-assisted coil embolization and Solitaire stent-assisted coil embolization for management of intracranial wide-neck carotid aneurysms. METHODS: We retrospectively analyzed the data of 86 patients with intracranial wide-neck carotid aneurysm treated in our hospital between June, 2016 and June, 2019. Forty-three of the patients received LVIS stent-assisted coil tamponade and the other 43 received Solitaire stentassisted coil tamponade. Arteriography was performed during, immediately after, and at 3 months after the surgery. The immediate embolization rate, surgical complications (vascular spasm, acute thrombus, coil escape, and bleeding), and the recurrence rate were compared between the two groups. RESULTS: In the LVIS stent group, 37 aneurysms were completely embolized, 5 were nearly fully embolized, and 1 was partially embolized, as compared with the numbers of 35, 6, and 2 in the Solitaire stent group, respectively. Surgery-related complications occurred in 5 patients in LVIS stent group and 3 in Solitaire stent group. Follow-up digital subtraction angiography (DSA) at 3 months after the operation revealed 4 recurrent aneurysms, including 1 in LVIS group and 3 in Solitaire stent group. All the patients had favorable outcomes that did not differ significantly between the two groups. CONCLUSIONS: Stent-assisted spring coils can achieve a high rate of complete and near-total embolization for intracranial aneurysms and is associated with a low incidence of neurological complications and favorable prognosis of the patients. The embolization rate, complications and recurrence rate are comparable between LVIS stent and Solitaire stent.

Rapid identification and pharmacokinetic studies of multiple active alkaloids in rat plasma through UPLC-Q-TOF-MS and UPLC-MS/MS after the oral administration of Zanthoxylum nitidum extract.

Zanthoxylum nitidum (Roxb.) DC. (ZN) belongs to the genus Zanthoxylum of Rutaceae and has various chemical ingredients and pharmacologic effects. Alkaloids are its main active constituents responsible for diverse pharmacologic effects, such as anti-tumor, anti-bacterial, anti-inflammatory, and analgesic activities. The chemical and pharmacological effects of ZN are well reported, but the in vivo pharmacokinetic profiles of its main active alkaloids are poorly investigated. This study aims to elucidate the absorbed constituents and pharmacokinetic behavior of main active ingredients in rat plasma after the oral administration of ZN extract. The absorbed constituents in rat plasma were qualitatively analyzed using ultra-high-performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Ultra-high-performance liquid chromatography with triple quadrupole mass spectrometry (UPLC-MS/MS) method was developed for the simultaneous determination and pharmacokinetic studies of dihydrochelerythrine (DHCHE), nitidine chloride (NIT), chelerythrine (CHE), sanguinarine (SAN), liriodenine (LIR), skimmianine (SKI), γ-fagarine (FAG), and dictamnine (DIC) in rat plasma. Eighteen prototypes and metabolites were identified according to exact mass, characteristic diagnostic fragment ions, and reference standards. The established UPLC-MS/MS quantitative method met the requirements of FDA for biological analysis methods. Method validation showed that this method has good linearity (r ≥ 0.9910), precision (RSD ≤ 18.63 %), accuracy (88.11 %-117.50 %), and stability. The limit of detection (LOD) could reach 1 ng/mL, and the limit of quantitation could reach 2 ng/mL. The plasma drug concentration of benzophenanthridine alkaloids, such as NIT, CHE, and DHCHE, were still low even after dose differences were deducted. For the furan quinoline alkaloids (such as SKI, FAG, and DIC), only SKI showed high plasma drug concentration, although SKI content comprised only approximately 1/6 of benzophenanthridine alkaloids. This study is the first to simultaneously determine the above-mentioned active alkaloids in rat plasma and would contribute to the comprehensive understanding of in vivo pharmacokinetic behavior on active alkaloids in ZN extract.

Identification and characterization of forced degradation products and stability-indicating assay for notoginsenosidefc by using UHPLC-Q-TOF-MS and UHPLC-MS/MS: Insights into stability profile and degradation pathways.

Notoginsenoside Fc, a protopanaxadiol-type saponin, shows multi-pharmacological activities. Chemical stability evaluation plays a crucial role in drug development. In this study, the forced degradation behavior of Notoginsenoside Fc was investigated under hydrolytic and oxidative conditions. A specific ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry was developed for the separation, identification, and characterization of the degradation products of Notoginsenoside Fc. Fifty potential degradation products were formed via deglycosylation, dehydration, hydration, isomerization, side-chain cleaving, oxidation, and superoxidation. Notoginsenoside Fc was subjected to different pH solutions, temperatures, and time periods to assess its stability. A sensitive ultra high performance liquid chromatography-tandem mass spectrometry was developed for the quantification of Notoginsenoside Fc, notoginsenoside ST-4, notoginsenoside Ft1, and relative quantification of notoginsenoside Ft2, 20(R)-notoginsenoside Ft2, notoginsenoside SFt3, and notoginsenoside SFt4. The assay was linear over the concentration range (R2  > 0.997) with the lowest limit of quantification of 0.02 µg/mL for Notoginsenoside Fc, Notoginsenoside ST-4, and Notoginsenoside Ft1. The intra-day precision, inter-day precision, and accuracy of the three analytes were within accepted levels. The degradation kinetics of Notoginsenoside Fc in pH 1 and 3 solutions fits to first- and second-order kinetics, respectively. The degradation of Notoginsenoside Fc is pH-, temperature-, and time-dependent.

Analogous ß-Carboline Alkaloids Harmaline and Harmine Ameliorate Scopolamine-Induced Cognition Dysfunction by Attenuating Acetylcholinesterase Activity, Oxidative Stress, and Inflammation in Mice.

The analogous ß-carboline alkaloids, harmaline (HAL) and harmine (HAR), possess a variety of biological properties, including acetylcholinesterase (AChE) inhibitory activity, antioxidant, anti-inflammatory, and many others, and have great potential for treating Alzheimer's disease (AD). However, studies have showed that the two compounds have similar structures and in vitro AChE inhibitory activities but with significant difference in bioavailability. The objective of this study was to comparatively investigate the effects of HAL and HAR in memory deficits of scopolamine-induced mice. In the present study, mice were pretreated with HAL (2, 5, and 10 mg/kg), HAR (10, 20, and 30 mg/kg) and donepezil (5 mg/kg) by intragastrically for 7 days, and were daily intraperitoneal injected with scopolamine (1 mg/kg) to induce memory deficits and then subjected to behavioral evaluation by Morris water maze. To further elucidate the underlying mechanisms of HAL and HAR in improving learning and memory, the levels of various biochemical factors and protein expressions related to cholinergic function, oxidative stress, and inflammation were examined. The results showed that HAL and HAR could effectively ameliorate memory deficits in scopolamine-induced mice. Both of them exhibited an enhancement in cholinergic function by inhibiting AChE and inducing choline acetyltransferase (ChAT) activities, and antioxidant defense via increasing the antioxidant enzymes activities of superoxide dismutase and glutathione peroxidase, and reducing maleic diadehyde production, and anti-inflammatory effects through suppressing myeloperoxidase, tumor necrosis factor α, and nitric oxide as well as modulation of critical neurotransmitters such as acetylcholine (ACh), choline (Ch), L-tryptophan (L-Trp), 5-hydroxytryptamine (5-HT), γ-aminobutyric acid (γ-GABA), and L-glutamic acid (L-Glu). Furthermore, the regulations of HAL on cholinergic function, inflammation, and neurotransmitters were more striking than those of HAR, and HAL manifested a comparable antioxidant capacity to HAR. Remarkably, the effective dosage of HAL (2 mg/kg) was far lower than that of HAR (20 mg/kg), which probably due to the evidently differences in the bioavailability and metabolic stability of the two analogs. Taken together, all these results revealed that HAL may be a promising candidate compound with better anti-amnesic effects and pharmacokinetic characteristics for the treatments of AD and related diseases.

Enantioselective synthesis of Janus kinase inhibitor INCB018424 via an organocatalytic aza-Michael reaction.

An enantioselective synthesis of INCB018424 via organocatalytic asymmetric aza-Michael addition of pyrazoles (16 or 20) to (E)-3-cyclopentylacrylaldehyde (23) using diarylprolinol silyl ether as the catalyst was developed. Michael adducts (R)-24 and (R)-27 were isolated in good yield and high ee and were readily converted to INCB018424.

Spongipyran Synthetic Studies. Total Synthesis of (+)-Spongistatin 2.

Evolution of a convergent synthetic strategy to access (+)-spongistatin 2 (2), a potent cytotoxic marine macrolide, is described. Highlights of the synthesis include: development of a multicomponent dithiane-mediated linchpin union tactic, devised and implemented specifically for construction of the spongistatin AB and CD spiro ring systems; application of a Ca(II) ion controlled acid promoted equilibration to set the thermodynamically less stable axial-equitorial stereogenicity in the CD spiroketal; use of sulfone addition/Julia methylenation sequences to unite the AB and CD fragments and introduce the C(44)-C(51) side chain; and fragment union and final elaboration to (+)-spongistatin 2 (2) exploiting Wittig olefination to unite the advanced ABCD and EF fragments, followed by regioselective Yamaguchi macrolactonization and global deprotection. Correction of the CD spiro ring stereogenicity was subsequently achieved via acid equilibration in the presence of Ca(II) ion to furnish (+)-spongistatin 2 (2). The synthesis proceeded with a longest linear sequence of 41 steps.

Discovery of a potent, selective, and orally active human epidermal growth factor receptor-2 sheddase inhibitor for the treatment of cancer.

The design, synthesis, evaluation, and identification of a novel class of (6S,7S)-N-hydroxy-6-carboxamide-5-azaspiro[2.5]octane-7-carboxamides as the first potent and selective inhibitors of human epidermal growth factor receptor-2 (HER-2) sheddase is described. Several compounds were identified that possess excellent pharmacodynamic and pharmacokinetic properties and were shown to decrease tumor size, cleaved HER-2 extracellular domain plasma levels, and potentiate the effects of the humanized anti-HER-2 monoclonal antibody (trastuzumab) in vivo in a HER-2 overexpressing cancer murine xenograft model.

Identification of ADAM10 as a major source of HER2 ectodomain sheddase activity in HER2 overexpressing breast cancer cells.

Overexpression and activating mutations of ErbB family members have been implicated in the development and progression of a variety of tumor types. Cleavage of the HER2 receptor by an as yet unidentified ectodomain sheddase has been shown to liberate the HER2 extracellular domain (ECD) leaving a fragment with constitutive kinase activity that can provide ligand-independent growth and survival signals to the cell. This process is clinically relevant since HER2 ECD serum levels in metastatic breast cancer patients are associated with a poorer prognosis. Thus, inhibition of the HER2 sheddase may provide a novel therapeutic approach for breast cancer. We describe the use of transcriptional profiling, pharmacological and in vitro approaches to identify the major source of HER2 sheddase activity. Real-time PCR was used to identify those ADAM family members which were expressed in HER2 shedding cell lines. siRNAs that selectively inhibited ADAM10 expression reduced HER2 shedding. In addition, we profiled over 1000 small molecules for in vitro inhibition of a panel of ADAM and MMP proteins; a positive correlation was observed only between ADAM10 inhibition and reduction of HER2 ECD shedding in a cell based assay. Finally, in vitro studies demonstrate that in combination with low doses of Herceptin, selective ADAM10 inhibitors decrease proliferation in HER2 overexpressing cell lines while inhibitors, that do not inhibit ADAM10, have no impact. These results are consistent with ADAM10 being a major determinant of HER2 shedding, the inhibition of which, may provide a novel therapeutic approach for treating a variety of cancers with active HER2 signaling.