Purification, Characterization and in vitro Anti-Tumor Activity of Proteins from Arca subcrenata Lischke

Identification and Characterization of a Novel Protein ASP-3 Purified from Arca subcrenata and Its Antitumor Mechanism

Diverse bioactive substances derived from marine organisms have been attracting growing attention. Besides small molecules and polypeptides, numerous studies have shown that marine proteins also exhibit antitumor activities. Small anticancer proteins can be expressed in vivo by viral vectors to exert local and long-term anticancer effects. Herein, we purified and characterized a novel protein (ASP-3) with unique antitumor activity from Arca subcrenata Lischke. The ASP-3 contains 179 amino acids with a molecular weight of 20.6 kDa. The spectral characterization of ASP-3 was elucidated using Fourier Transform infrared spectroscopy (FTIR) and Circular Dichroism (CD) spectroscopy. Being identified as a sarcoplasmic calcium-binding protein, ASP-3 exhibited strong inhibitory effects on the proliferation of Human hepatocellular carcinoma (HepG2) cells with an IC₅₀ value of 171.18 ± 18.59 μg/mL, measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The RNA-seq analysis showed that ASP-3 regulated the vascular endothelial growth factor receptor (VEGFR) signaling pathway in HepG2 cells. Immunofluorescence results indicated that ASP-3 effectively reduced VEGFR2 phosphorylation in HepG2 cells and affected the downstream components of VEGF signaling pathways. The surface plasmon resonance (SPR) analysis further demonstrated that ASP-3 direct interacted with VEGFR2. More importantly, the therapeutic potential of ASP-3 as an anti-angiogenesis agent was further confirmed by an in vitro model using VEGF-induced tube formation assay of human umbilical vein endothelial cells (HUVECs), as well as an in vivo model using transgenic zebrafish model. Taken together, the ASP-3 provides a good framework for the development of even more potent anticancer proteins and provides important weapon for cancer treatment using novel approaches such as gene therapy.

Arca subcrenata Polypeptides Inhibit Human Colorectal Cancer HT-29 Cells Growth via Suppression of IGF-1R/Akt/mTOR Signaling and ATP Production

Arca subcrenata Lischke, widely scattering offshore at neritic regions, is very popular on dining table due to its edible and medical functional meatball. This study aims to investigate the suppression of a polypeptide fraction from A. subcrenata (PAS) on human colorectal cancer HT-29 cells, and its underlying mechanism. The results showed that PAS inhibited the growth of HT-29 cells with an IC₅₀ value of 117 μg/ml after 48 h treatment, and significantly suppressed the tumor growth in nude mice bearing-xenografted HT-29 cells at the dosage of 63 mg/kg, with little influence on normal colon cells and normal colonic mucosa. PAS was then inspiringly found to induce apoptosis and G2/M phase arrest in HT-29 cells. The effect mechanism was involved in the inhibition of IGF-1/IGF-1R signaling activation, which was responsible for inactivating downstream Akt/mTOR pathway. Immunofluorescence assay also showed that PAS could reduce phosphorylation of IGF-1R (Tyr1165/1166). IGF-1, an IGF-1R activator, could reverse the suppression of PAS on IGF-1R phosphorylation. Furthermore, PAS significantly inhibited ATP production of HT-29 cells both in vitro and in vivo. Our results provide positive evidence that A. subcrenata has the potential to be a candidate for the treatment of colorectal cancer.

Application of UPLC-MS/MS to simultaneously detect four bioactive compounds in the tumour-shrinking decoction (FM1523) for uterine fibroids treatment

INTRODUCTION

The Chinese medicine formulation, tumour-shrinking decoction (TSD, FM1523), which consists of 15 natural medicines, is used for uterine fibroids (UFs) therapy and possesses excellent clinical therapeutic effect.

OBJECTIVE

To develop a sensitive and validated analytical method for the simultaneous quantification of four crucial bioactive compounds including isorhamnetin-3-O-neohesperidoside, curcumin, peimine and tetrahydropalmatine in the principal formulation of this decoction.

METHODS

An ultra-performance liquid chromatography coupled tandem mass spectrometry (UPLC-MS/MS) with an electrospray ionisation (ESI) source in multiple reaction monitoring (MRM) mode was conducted to investigate these bioactive compounds in the TSD. The chromatographic separation was performed on a C18 column when the flow rate was adjusted at 0.2 mL/min with gradient elution of acetonitrile-water with 0.1% formic acid. Accelerated solvent extraction (ASE) method with higher extraction efficiency was employed for TSD sample pre-treatment.

RESULTS

The linearity, limit of detection (LOD) and limit of quantification (LOQ) were determined for this analytical method. The mean recoveries of the compounds were determined between 100.23% and 104.02% with satisfactory relative standard deviation (RSD) in the ranges of 2.65% to 3.81%. The precision was evaluated by intra-day and inter-day tests, which revealed RSD within the ranges of 1.21% to 2.14% and 1.24% to 2.32%, respectively.

CONCLUSION

The bioactive compounds of TSD samples were successfully quantified via UPLC-MS/MS with MRM mode. This study could help to evaluate the pharmacokinetic study of TSD during clinical applications and present a facile strategy for quantifying bioactive compounds in traditional Chinese Medicine decoction.

Purification and structural characterization of a novel antioxidant and antibacterial protein from Arca inflata

A novel protein (J2-C4) with antioxidant and antibacterial activities was purified from the edible portion of Arca inflata. The purity of J2-C4 was measured to be 97.62% by RP-HPLC analysis, and the molecular weight was 20,537.0 Da by ESI-MS/MS. The isoelectric point of J2-C4 was determined to be 5.18 by IEF-PAGE. Secondary structure analysis of J2-C4 showed that it contained 34.9% α-helix, 15.0% β-sheet, 16.3% β-turn and 34.0% random coil by CD spectroscopy. The complete amino acid sequence of J2-C4 was identified by gel electrophoresis and LC-MS/MS together with transcriptome database analysis. Based on the alignment with NCBI BLAST database, J2-C4 showed 71% homology with a sarcoplasmic calcium-binding protein isolated from Crassostrea virginica. Therefore, J2-C4 was proposed to be a new sarcoplasmic calcium-binding protein-like protein in A. inflata. In vitro antioxidant assays showed that J2-C4 exhibited favorable scavenging activities on ABTS⁺ (EC₅₀ 145.80 μg/mL) and DPPH (EC₅₀ 455.62 μg/mL). J2-C4 exhibited antibacterial activities against Pseudomonas aeruginosa (MIC: 375 μg/mL), Escherichia coli (MIC: 187.5 μg/mL) and Methicillin resistant Staphylococcus aureus (MIC: 750 μg/mL). The results showed that J2-C4 might be developed as a potential food additive agent.

Purification and partial characterization of a new antitumor protein from Tegillarca granosa

A new protein, coded as D2-3, was obtained from the marine organism Tegillarca granosa L. by anion exchange and hydrophobic chromatography. The purity of D2-3 was over 99.0% as measured by RP-HPLC. Its molecular weight was shown to be 20.320 kDa by ESI-MS/MS, and the isoelectric point of D2-3 was 4.70. The antitumor activity of D2-3 against four human tumor cell lines was measured by MTT assay. The conformational structure of D2-3 was further characterized by UV-vis, FT-IR and CD spectroscopy. Partial amino acid sequences of D2-3 were determined to be LMMTDVEESR, SSHMLSECRRK, KNGRNVDISHKDKG, SSDPTLMDPDDTNKDR, SSDKNTCSKTEYYTR and SSETMPYDVLDTNEMR via MALDI-TOF-MS and de novo sequencing.

A new in vitro anti-tumor polypeptide isolated from Arca inflata

A new in vitro anti-tumor polypeptide, coded as J2-C3, was isolated from Arca inflata Reeve and purified by diethyl-aminoethanol (DEAE)-sepharose Fast Flow anion exchange and phenyl sepharose CL-4B hydrophobic chromatography. J2-C3 was identified to be a homogeneous compound by native polyacrylamide gel electrophoresis (Native-PAGE). The purity of J2-C3 was over 99% in reversed phase-high performance liquid chromatography (RP-HPLC). The molecular weight was determined as 20,538.0 Da by electrospray-ionization mass spectrometry (ESI-MS/MS). J2-C3 was rich in Glx (Gln + Glu), Lys, and Asx (Asp + Asn) according to amino acid analysis. Four partial amino acid sequences of this peptide were determined as L/ISMEDVEESR, KNGMHSI/LDVNHDGR, AMKI/LI/LNPKKGI/LVPR and AMGAHKPPKGNEL/IGHR via MALDI-TOF/TOF-MS and de novo sequencing. Secondary structural analysis by CD spectroscopy revealed that J2-C3 had the α-helix (45.2%), β-sheet (2.9%), β-turn (26.0%) and random coil (25.9%). The anti-tumor effect of J2-C3 against human tumor cells was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and the IC₅₀ values of J2-C3 were 65.57, 93.33 and 122.95 µg/mL against A549, HT-29 and HepG2 cell lines, respectively. Therefore, J2-C3 might be developed as a potential anti-tumor agent.

A new antiproliferative and antioxidant peptide isolated from Arca subcrenata

A new antitumor and antioxidant peptide (H3) was isolated from Arca subcrenata Lischke using ion exchange and hydrophobic column chromatography. The purity of H3 was over 99.3% in reversed phase-high performance liquid chromatography (RP-HPLC) and the molecular weight was determined to be 20,491.0 Da by electrospray-ionization mass spectrometry (ESI-MS/MS). The isoelectric point of H3 was measured to be 6.65 by isoelectric focusing-polyacrylamide gel electrophoresis. Partial amino acid sequence of this peptide was determined as ISMEDVEESRKNGMHSIDVNHDGKHRAYWADNTYLM-KCMDLPYDVLDTGGKDRSSDKNTDLVDLFELDMVPDRKNNECMNMIMDVIDTN-TAARPYYCSLDVNHDGAGLSMEDVEEDK via MALDI-TOF/TOF-MS and de novo sequencing. The in vitro antitumor activity of H3 was evaluated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The result indicated that H3 exhibited significant antiproliferative activity against HeLa, HepG2 and HT-29 cell lines with IC₅₀ values of 10.8, 10.1 and 10.5 μg/mL. The scavenging percentage of H3 at 8 mg/mL to 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals were 56.8% and 47.5%, respectively.

Antitumor effect of a polypeptide fraction from Arca subcrenata in vitro and in vivo

Arca subcrenata Lischke is a marine traditional Chinese medicine. The study investigated the antitumor effects of P2, a polypeptide fraction from A. subcrenata, and its toxicity in vitro and in vivo. The results showed that P2 could inhibit the proliferation of seven tumor cell lines, especially in HeLa and HT-29 cell lines. The IC₅₀ values were 11.43 μg/mL for HeLa and 13.00 μg/mL for HT-29 treated by P2 for 48 h. P2 had little cytotoxicity on normal liver cells (L-02). The maximum tolerated dose (MTD) of P2 on KM mice was 1000 mg/kg by i.p. or i.v. The tumor growth inhibitory ratios of P2 were 26.4%, 41.4% and 46.4% for H-22, and 34.0%, 45.8% and 60.1% for S-180 tumor-bearing mice. The results demonstrated that P2 might be a potential antitumor agent with high efficiency in dose-dependent and time-dependent manners and low toxicity.

Screening for in vitro cytotoxic activity of seaweed, Sargassum sp. against Hep-2 and MCF-7 cancer cell lines

Discovery of anticancer drugs that kill or disable tumor cells in the presence of normal cells without undue toxicity is a potential challenge for therapeutic care. Several papers in the literature have emphasized the potential implications of marine products such as seaweeds which exhibit antitumor activity. Study attempts to screen the antitumor effect of Sargassum sp, against chosen cell lines such as MCF-7 (Breast cancer) and Hep-2 (Liver Cancer). Ethanol extract of Sargassum sp. was concentrated using a Soxhlet apparatus and dissolved in DMSO. In vitro cytotoxic activity of Sargassum sp at various concentrations (100 μg/ml-300 μg/ml) screened for antitumor effect against the chosen cell lines using MTT assay (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide, a yellow tetrazole). The study documented that the percentage of cell viability has been reduced with increased concentration, as evidenced by cell death. Sargassum sp extract shows potential cytotoxic activity (P≤0.05) with IC50 of 200 μ g/ml and 250 μg/ml against Hep-2 and MCF-7 cell lines respectively. The ethanol fraction of Sargassum sp induced cell shrinkage, cell membrane blebbing and formation of apoptotic bodies with evidence of bioactive components as profound influencing factors for anti-tumor effects. Further research need to be explored for the successful application of Sargassum sp as a potent therapeutic tool against cancer.

Purification, characterization and antitumor activities of a new protein from Syngnathus acus, an officinal marine fish

Discovery and development of new antitumor agents from abundant marine fish are attracting an increasing interest. In the present study, we extracted and purified a novel antitumor protein Syngnathusin from the whole body of Syngnathus acus L., a precious marine fish traditionally used for tumors. Syngnathusin was comprised of 16 kinds of amino acids, mainly acidic amino acids. Its molecular weight was 67.3 kDa and its isoelectric point was 4.57. The N-terminal amino acid sequence of Syngnathusin was determined to be Lys-Arg-Asp-Leu-Gly-Phe-Val-Asp-Glu-Ile-Ser-Ala-His-Tyr and showed no significant homology with the known proteins. Syngnathusin could significantly inhibit the growth of A549 and CCRF-CEM cells. However, the obvious proliferation inhibition against human non-tumor cell lines was not observed. Flow cytometry, morphologic assessment and comet assay revealed that Syngnathusin could induce apoptosis in A549 and CCRF-CEM cells and strongly cooperated with MTX. Syngnathusin could inhibit the growth of S180 tumor transplanted in mice. Syngnathusin may be developed as a novel, selective and effective antineoplastic agent.

Antioxidant activities of hydrolysates of Arca subcrenata prepared with three proteases

In order to get products with antioxidant activity from Arca subcrenata Lischke, the optimal hydrolase and hydrolysis conditions were investigated in the paper. Three proteases (neutrase, alcalase and papain) were applied to hydrolyze the homogenate of A. subcrenata. An orthogonal design was used to optimize hydrolysis conditions, and the pH-stat methods was used to determine the degree of hydrolysis. Viewed from the angle of reducing power, such as scavenging activities against α,α-diphenyl-β-picrylhydrazyl (DPPH) radical and hydrogen peroxide, the antioxidant activities of the alcalase hydrolysate (AH) were superior to neutrase hydrolysate (NH) and papain hydrolysate (PH), and its EC₅₀ values in DPPH radical and hydrogen peroxide scavenging effect were 6.23 mg/ml and 19.09 mg/ml, respectively. Moreover, compared with products hydrolyzed by neutrase and papain, the molecular mass of AH was lower and its content of amino acid of peptides was higher. Therefore, alcalase was selected as the optimal enzyme to produce active ingredients since its hydrolysate exhibited the best antioxidant activity among them and possessed large amount of potential active peptides.