Cell-Penetrating Peptides for Use in Development of Transgenic Plants

Genetically modified plants and crops can contribute to remarkable increase in global food supply, with improved yield and resistance to plant diseases or insect pests. The development of biotechnology introducing exogenous nucleic acids in transgenic plants is important for plant health management. Different genetic engineering methods for DNA delivery, such as biolistic methods, Agrobacterium tumefaciens-mediated transformation, and other physicochemical methods have been developed to improve translocation across the plasma membrane and cell wall in plants. Recently, the peptide-based gene delivery system, mediated by cell-penetrating peptides (CPPs), has been regarded as a promising non-viral tool for efficient and stable gene transfection into both animal and plant cells. CPPs are short peptides with diverse sequences and functionalities, capable of agitating plasma membrane and entering cells. Here, we highlight recent research and ideas on diverse types of CPPs, which have been applied in DNA delivery in plants. Various basic, amphipathic, cyclic, and branched CPPs were designed, and modifications of functional groups were performed to enhance DNA interaction and stabilization in transgenesis. CPPs were able to carry cargoes in either a covalent or noncovalent manner and to internalize CPP/cargo complexes into cells by either direct membrane translocation or endocytosis. Importantly, subcellular targets of CPP-mediated nucleic acid delivery were reviewed. CPPs offer transfection strategies and influence transgene expression at subcellular localizations, such as in plastids, mitochondria, and the nucleus. In summary, the technology of CPP-mediated gene delivery provides a potent and useful tool to genetically modified plants and crops of the future.

[Progress in research of etiology of childhood obesity based on interaction between genes and environment]

Childhood obesity is a global public health problem, which can not only endangers children's health, but also might be an important cause of chronic diseases in adulthood. In recent years, with the in-depth development of precision medicine research, more and more research evidences have shown that there are interactions between environmental factors, such as early intrauterine environment, children's diet, physical activity and children's gene factor on the incidence of childhood obesity, which can result in or inhibit the incidence and development of childhood obesity. This paper summarizes the progress in research in this field to reveal the effects and potential mechanisms of genetic factors and environmental factors on the incidence of childhood obesity in order to provide reference for the precise prevention and control of childhood obesity under different genetic backgrounds.

[Efficacy and safety of neoadjuvant chemotherapy combined with PD-1 antibody for esophageal squamous cell carcinoma in the real world]

Objective: To evaluate the efficacy and safety of neoadjuvant chemotherapy combined with programmed death-1 (PD-1) antibody in operable, borderline or potentially resectable locally advanced esophageal squamous cell carcinoma(ESCC) in the real world. Methods: The study retrospectively analyzed 28 patients with operable or potentially resectable locally advanced ESCC patients treated with preoperative chemotherapy combined with PD-1 inhibitor in Nanjing Drum Tower Hospital, Affiliated Hospital of Nanjing University Medical School from April 2020 to March 2021. According to the clinical TNM staging system of the 8th edition of the American Joint Committee on Cancer, there were 1, 15, 10, 1 and 1 case of stage Ⅱ, Ⅲ, ⅣA, ⅣB and unknown stage respectively. The treatment was two cycle of dual drug chemotherapy regimen including taxane plus platinum or fluorouracil combined with PD-1 antibody followed by tumor response assessment and surgery if the patient was eligible for resection. Results: Of the 28 patients, 1, 2, 3 and 4 cycles of chemotherapy combined with PD-1 antibody treatment completed in 1, 21, 5, and 1 patient, respectively. Objective response rate (ORR) was 71.4% (20/28), and disease control rate (DCR) was 100% (28/28). The incidence of adverse events exceeding grade 3 levels was 21.4% (6/28), including 3 neutropenia, 1 leukopenia, 1 thrombocytopenia and 1 immune hepatitis. There was no treatment-related death. Of the 23 patients underwent surgery, R0 resection rate was 87.0% (20/23), 13 patients had down staged to the T1-2N0M0 I stage, the pCR rate was 17.3% (4/23), and the pCR rate of primary tumor was 21.7% (5/23). Four patients received definitive chemoradiotherapy. One patient rejected surgery and other treatment after achieved PR response. Conclusion: Neoadjuvant chemotherapy combined PD-1 inhibitor is safe and has high efficacy in operable, borderline or potentially resectable locally advanced ESCC, and it is a promising regimen.

Effect of Size and Concentration of Copper Nanoparticles on the Antimicrobial Activity in Escherichia coli through Multiple Mechanisms

Metal and metal oxide nanoparticles, including copper nanoparticles (CuNPs), display antimicrobial activities and are regarded as promising microorganism inhibitors. Here, we explored the antimicrobial activity of CuNPs in Escherichia coli (E. coli) using two particle sizes (20 and 60 nm) and five concentrations (1, 5, 10, 50 and 100 μg/mL). The result showed a concentration-dependent trend of bactericidal activities for both size groups, with 20 nm particles more effective than 60 nm particles at low concentrations. The membrane disruption caused by CuNPs was confirmed by electron microscopy, PI staining and protein leaking analysis. However, the results of reactive oxygen species generation and genomic DNA damage revealed that the size and concentration of CuNPs were factors affecting the induction of multiple bactericidal mechanisms simultaneously on different scales. Further results of annexin V-PI staining supported this hypothesis by showing the shifting composition of the early-, late- and non-apoptotic dead cells across the CuNP groups. Many CuNP treatment groups were rescued when four mammalian modulators-wortmannin, necrosulfonamide, Z-VAD-FMK, and SBI-0206965-were applied separately. The results suggest the possible existence of bacterial programmed cell death pathways in E. coli which could be triggered by CuNP treatments.

Novel and Practical Approaches to Manage Diet-induced Metabolic Disorders: Part-I

Metabolic syndrome (MetS) which is caused by poor dietary habits and sedentary behavior is a serious global health problem. MetS is a cluster of risk factors, represented by central obesity, hyperglycemia, dyslipidemia, and hypertension. In the 21st century, MetS and associated comorbidities, including obesity, diabetes and cardiovascular diseases, are the major threats to human health. Practical dietary strategies, nutritional bioactive compounds and a healthy lifestyle are claimed to be efficient in the management of one or more components of MetS. Nevertheless successful management of MetS and commodities is still a major concern. Since hyperglycemia, inflammation and redox imbalance are intrinsically involved in the progression of MetS comorbidities, finding effective strategies that precisely target these systems is highly warranted. In this scenario, pharmacological and non-pharmacological approaches with or without dietary patterns, phytochemicals or exercise interventions are the practical strategies to combat MetS and associated diseases. However, designing and prescribing of optimal nutritional patterns and exercise regimens remains a big challenge to achieve the maximum beneficial effects. This thematic issue addressed the concerns and provided practical strategies to overcome the malady of MetS in the modern world.

Clinical significance of epithelial-mesenchymal transition-related molecules in lung adenocarcinoma

Background

Epithelial-mesenchymal transition (emt) refers to the biologic process in which epithelial cells are transformed into interstitial phenotypes by specific pathways. This transition plays an important biologic role in the process by which epithelium-derived malignant tumour cells acquire the ability to migrate and invade. We explored the relationship between emt-associated molecules and patient-related clinical factors to determine whether any clinical characteristics could be used as biomarkers for emt-related protein alterations in lung cancer-especially lung adenocarcinoma.

Methods

Tumour specimens were collected from 80 patients with lung adenocarcinoma who underwent surgery or lung biopsy, with 4 patients being evaluated a 2nd time after re-biopsy. Expression of emt-related proteins, including E-cadherin and vimentin, was evaluated by immunohistochemistry. We analyzed the relationship between clinicopathologic characteristics and expression level of the emt markers.

Results

Positive expression of E-cadherin was observed in 63 patients (79%), and vimentin, in 46 patients (57.5%). No significant relationships between E-cadherin or vimentin expression and smoking history, sex, age, driving gene mutations, or cell differentiation were identified. A significant correlation was observed between vimentin expression and pathologic stage. Of the 4 patients who were evaluated a 2nd time after re-biopsy, 3 showed the same emt-related protein expression status as in the first analysis. In the remaining patient, E-cadherin had changed completely.

Conclusions

Clinicopathologic factors in cancer patients did not help to diagnose emt status in lung adenocarcinoma; however, TNM stage might be associated with vimentin expression.

[Helical tomotherapy using simultaneously integrated boost and simultaneous integrated protection technique for unresectable biliary tract cancer]

Objective: To evaluate the safety and efficacy of helical tomotherapy using simultaneously integrated boost and simultaneous integrated protection technique in the treatment of unresectable biliary tract cancers. Methods: The data of 23 patients with unresectable biliary tract cancer who received tomotherapy-based hypofractionated radiotherapy at Comprehensive Cancer Centre of Drum Tower Hospital,the Affiliated Drum Tower Clinical College of Nanjing Medical University between February 2015 and October 2017 were analyzed. There were 10 males and 13 females, aged from 40 to 85 years(median:58 years). Pathological type included intrahepatic cholangiocarcinomas(n=11), gallbladder cancers(n=6),extrahepatic cholangiocarcinomas(n=6). The irradiated sites covered primary tumors and areas of local invasion,including metastatic lymph nodes which were confined to the abdominal or retroperitoneal space. Dose escalation was achieved using simultaneously integrated boost(SIB) technique, and simultaneous integrated protection(SIP)technique was used to protect gastrointestinal tracts and other adjacent organs. Cox regression modal and Kaplan-Meier analysis were used to analyze the associations between patients' characteristics and overall survival(OS). Results: The median total radiation dose was 54 Gy(range: 28-72 Gy)and median biologically effective dose(BED)was 74.4 Gy(range: 37.8-115.2 Gy).The median planning target volume(PTV)was 445.79 cm(3)(range:126.02-950.12 cm(3)). Based on the various PTV,patients received 2.4-6.0 Gy/fraction with 8-28 fractions. The local control rate was 65.2% and the median OS was 11.3 months(range:2.1-31.9 months).The most common cause of death was out-field failure and only 3 patients died of in-field failures. The longest survival was 31.9 months. BED≥70 Gy significantly improved OS,compared to BED<70 Gy(16.8 months vs.5.1 months)(HR=0.146, 95%CI:0.028-0.762, P=0.022). No patients developed grade ≥4 toxicities. Conclusions: Helical tomotherapy-based hypofractionated radiotherapy is effective and well tolerated for patients with unresectable biliary tract cancer. The dose escalation with higher BED could improve the survival for such patients.

[Molecular origins of cancer and future cancer therapy]

The accumulation of genomic and epigenetic changes gives rise to the tumorigenesis and progression. Currently, clonal evolution model and cancer stem cell model, two leading theories of caner origin, are becoming complementary to one another to explain the nature of tumor heterogeneity. Precision medicine that is based on the next generation sequencing and big data describes the phenomena of tumor heterogeneity more precisely. The future cancer therapy may need more comprehensive and dynamical understandings of the distinct subclones of tumor and follow the trends of cancer evolution.

Effect of increased UV-B radiation on carotenoid accumulation and total antioxidant capacity in tobacco (Nicotiana tabacum L.) leaves

Carotenoids are important components of plant antioxidant systems, which protect photosystems from photooxidative destruction during ultraviolet-B (UV-B) exposure. The influence of carotenoids on total antioxidant capacity (TAC) of plants has rarely been studied. In this study, tobacco (Nicotiana tabacum L., 'K326') seedlings exposed to UV-B radiation were used in order to evaluate the effects of ambient levels of UV-B radiation on carotenoid accumulation. The aim was to investigate whether carotenoids could enhance TAC as a means of UV protection. Our results showed that leaf carotenoid content in the low UV-B exposure (+9.75 μW/cm2) plants was approximately 8% higher than that observed in control plants at 2-8 days of exposure. At high UV-B exposure (+20.76 μW/cm2), the carotenoid content increased rapidly after 1 day's exposure (10.41% higher than the control), followed by a return to the content as in control plants. Furthermore, carotenoid content positively correlated with TAC (P = 0.024). These results suggest that carotenoids have antioxidant properties and play an important role in the antioxidant system. UV-B exposure increased the carotenoid synthesis capability of plants. The plants could deplete the carotenoids to scavenge excess ROS at high UV-B radiation levels, which protects the tobacco plant from oxidative damage caused by UV-B stress.

[Chinese multicenter randomized trial of customized chemotherapy based on BRCA1 (breast cancer susceptibility gene 1)-RAP80 (receptor-associated protein 80) mRNA expression in advanced non-small cell lung cancer (NSCLC) patients]

Objective: BRCA1 (breast cancer susceptibility gene 1) and RAP80 (receptor-associated protein 80) play key roles in predicting chemosensitivity of platinum and taxanes. A randomized trial was carried out to compare non-selected cisplatin-based chemotherapy with therapy customized according to BRCA1 and RAP80 expression. Methods: Advanced stage NSCLC patients whose tumor specimen was sufficient for molecular analysis were randomized (1∶3) to the control or experimental arm. Patients in the control arm received docetaxel/cisplatin; in the experimental arm, patients with low RAP80 expression received gemcitabine/cisplatin (Arm 1), those with intermediate/high RAP80 expression and low/intermediate BRCA1expression received docetaxel/cisplatin (Arm 2), and those with intermediate/high RAP80 expression and high BRCA1 expression received docetaxel alone (Arm 3). The primary end point was progression-free survival (PFS). Results: 226 patients were screened and 124 were randomized in this trial. ORR in the four subgroups was 22.6%, 48.4%, 30.3% and 19.2%, respectively (P=0.08); PFS was 4.74, 5.59, 3.78 and 2.73 months, respectively (P=0.55); and OS was 10.82, 14.44, 10.86 and 10.86 months, respectively (P=0.84). The common adverse effects included neutropenia, nausea, anemia and fatigue. Conclusions: No statistically significant difference of ORR, PFS or OS is observed in the experimental arms compared with the control arm. Patients with low RAP80 mRNA levels have a trend of better survival and higher response rate to gemcitabine/cisplatin chemotherapy.

[Research advances of K-ras mutation in the prognosis and targeted therapy of gastric cancer]

K-ras mutations have been described in 30% of human cancers with significantly different mutation frequencies. High K-ras mutation frequency is found in many cancers such as pancreas and lung cancers, whereas, gastric cancer has a relatively low K-ras mutation frequency. In recent years, numerous researches have focused on the K-ras mutation in gastric cancer. This review summarizes the K-ras mutation frequency in gastric cancer, the relationship of K-ras mutation with clinicopathologic features and prognosis of gastric cancer patients, targeted therapy for K-ras mutated gastric cancer, some small-molecular inhibitors of K-ras, and development of targeted therapy drugs for K-ras signaling pathway in gastric cancer.

Delivery of nucleic acids, proteins, and nanoparticles by arginine-rich cell-penetrating peptides in rotifers

Cell-penetrating peptides (CPPs) are a group of short, membrane-permeable cationic peptides that represent a nonviral technology for delivering nanomaterials and macromolecules into live cells. In this study, two arginine-rich CPPs, HR9 and IR9, were found to be capable of entering rotifers. CPPs were able to efficiently deliver noncovalently associated with cargoes, including plasmid DNAs, red fluorescent proteins (RFPs), and semiconductor quantum dots, into rotifers. The functional reporter gene assay demonstrated that HR9-delivered plasmid DNAs containing the enhanced green fluorescent protein and RFP coding sequences could be actively expressed in rotifers. The 1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan assay further confirmed that CPP-mediated cargo delivery was not toxic to rotifers. Thus, these two CPPs hold a great potential for the delivery of exogenous genes, proteins, and nanoparticles in rotifers.

Cellular internalization of quantum dots

Cell-penetrating peptides (CPPs) can facilitate uptake of quantum dots (QDs) for a variety of basic and applied sciences. Here we describe a method that utilizes simple noncovalent interactions to complex QDs and CPPs. We further describe methods to study uptake mechanisms of the QD/CPP complex. The inhibitor study coupled with the RNA interference (RNAi) technique provides a comprehensive approach to elucidate cellular entry of the QD/CPP complex.

Protein transduction in human cells is enhanced by cell-penetrating peptides fused with an endosomolytic HA2 sequence

Endocytosis has been proposed as one of the primary mechanisms for cellular entry of cell-penetrating peptides (CPPs) and their cargoes. However, a major limitation of endocytic pathway is entrapment of the CPP-cargo in intracellular vesicles from which the cargo must escape into the cytoplasm to exert its biological activity. Here we demonstrate that a CPP tagged with an endosomolytic fusion peptide derived from the influenza virus hemagglutinin-2 (HA2) remarkably enhances the cytosolic delivery of proteins in human A549 cells. To determine the endosome-disruptive effects, recombinant DNA plasmids containing coding sequences of HA2, CPPs and red fluorescent proteins (RFPs) were constructed. The fusion proteins were purified from plasmid-transformed Escherichia coli, and their effects on protein transduction were examined using live cell imaging and flow cytometry. Our data indicate that endocytosis is the major route for cellular internalization of CPP-HA2-tagged RFP. Mechanistic studies revealed that the fusogenic HA2 peptide dramatically facilitates CPP-mediated protein entry through the release of endocytosed RFPs from endosomes into the cytoplasm. Furthermore, incorporating the HA2 fusion peptide of the CPP-HA2 fusion protein improved cytosolic uptake without causing cytotoxicity. These findings strongly suggest that the CPP-HA2 tag could be an efficient and safe carrier that overcomes endosomal entrapment of delivered therapeutic drugs.

Arginine-rich cell-penetrating peptides deliver gene into living human cells

Transgenesis is a process that introduces exogenous nucleic acids into the genome of an organism to produce desired traits or evaluate function. Improvements of transgenic technologies are always important pursuit in the last decades. Recently, cell-penetrating peptides (CPPs) were studied as shuttles that can internalize into cells directly and serve as carriers to deliver different cargoes into cells. In the present study, we evaluate whether arginine-rich CPPs can be used for gene delivery into human cells in a noncovalent fashion. We demonstrate that three arginine-rich CPPs (SR9, HR9, and PR9) are able to transport plasmid DNA into human A549 cells. For the functional gene assay, the CPP-delivered plasmid DNA containing the enhanced green fluorescent protein (EGFP) coding sequence could be actively expressed in cells. The treatment of calcium chloride did not facilitate the CPP-mediated transfection efficiency, but enhance the gene expression intensity. Mechanistic studies further revealed that HR9/DNA complexes mediate the direct membrane translocation pathway for gene delivery. Our results suggest that arginine-rich CPPs, especially HR9, appear to be a high efficient and promising tool for gene transfer.

A gene delivery system for insect cells mediated by arginine-rich cell-penetrating peptides

Most bioactive macromolecules, such as protein, DNA and RNA, basically cannot permeate into cells freely from outside the plasma membrane. Cell-penetrating peptides (CPPs) are a group of short peptides that possess the ability to traverse the cell membrane and have been considered as candidates for mediating gene and drug delivery into living cells. In this study, we demonstrate that three arginine-rich CPPs (SR9, HR9 and PR9) are able to form stable complexes with plasmid DNA and deliver DNA into insect Sf9 cells in a noncovalent manner. The transferred plasmid DNA containing enhanced green fluorescent protein (EGFP) and red fluorescent protein (RFP) coding regions could be expressed in cells functionally assayed at both the protein and RNA levels. Furthermore, treatment of cells with CPPs and CPP/DNA complexes resulted in a viability of 84-93% indicating these CPPs are not cytotoxic. These results suggest that arginine-rich CPPs appear to be a promising tool for insect transgenesis.

Wnt/β-catenin signaling regulates MAPK and Akt1 expression and growth of hepatocellular carcinoma cells

In hepatocellular carcinoma (HCC), Wnt/β-catenin, Ras/MAPK and PI3K/AKT signaling pathways form a complex network and play important roles during HCC genesis and development. To study their relationship and the influence on cell growth, the siRNA directed against β-catenin was transfected into HCC HepG2 cells. β-catenin mRNA and protein levels were measured respectively at various times by RT-PCR and Western blot. Furthermore, HCC cell growth was measured by MTT assay. Finally, MAPK family and Akt1 protein levels were also measured by Western blot. After the transfection, β-catenin mRNA levels were markedly inhibited at 24 h and increased gradually at 48, 72 and 96 h; β-catenin protein levels decreased gradually at 24, 48 and 72 h and slightly increased at 96 h. HCC cell growth was inhibited from 24-72 h, but this inhibition decreased at 96 h. ERK1/2 (p42/p44 MAPK), JNK/SAPK, p38 MAPK, and Akt1 protein levels showed no change following transfection, while their phosphorylated protein levels showed changes. Thus, siRNA directed against β-catenin markedly decreased β-catenin gene expression and inhibited cell growth. Wnt/β-catenin signaling pathway might regulate Ras/MAPK and PI3K/Akt signaling pathways through regulation of the phosphorylation state of ERK1/2, JNK/SAPK and Akt1 protein in HCC HepG2 cells. These pathways might compensate for the inhibitory effect of β-catenin, thereby affecting tumor cell growth and others downstream factors.

Silencing STAT3 may inhibit cell growth through regulating signaling pathway, telomerase, cell cycle, apoptosis and angiogenesis in hepatocellular carcinoma: potential uses for gene therapy

The genesis and development of hepatocellular carcinoma (HCC) is related to the abnormity of signaling pathway, telomerase, cell cycle, apoptosis, angiogenesis, and others, in which STAT3 signaling pathway plays a key role. The HCC cell line HepG2 was transfected with small interfering RNA (siRNA) directed against STAT3. After 72 h, cell growth and cycle were analysed by MTT and Flow cytometry. Then, the protein was extracted and the protein expression of STAT3, Smad3, p44/42, TERT, caspase-3, XIAP, Grp-78, HSP-27, MMP-2, MMP-9, VEGF-A, cyclin A, and cyclin E was detected by Western blot. After the transfection, HCC cell growth was inhibited during the 24-72 h time period and the cell cycle was arrested in G0/G1. STAT3 protein expression was inhibited at 72 h after the transfection. Interestingly, Smad3, p-caspase-3, p-p44/42, Grp78, cyclin A, and cyclin E protein expression was increased at 72 h, while TERT, caspase-3, XIAP, MMP-2, MMP-9, and VEGF-A protein expression decreased at 72 h. However, P44/42, and HSP27 protein expression showed no change following transfection. The results demonstrated that STAT3 signaling pathway may participate in HCC genesis and development through regulating the protein expression of other signaling pathway, telomerase, apoptosis, cell cycle and angiogenesis; thereby, blockade of the Stat3 pathway represents a potential strategy for future treatment.

KEYWORDS

STAT3, signaling pathway, telomerase, cell cycle, apoptosis, angiogenesis.

Arginine-rich intracellular delivery peptides synchronously deliver covalently and noncovalently linked proteins into plant cells

Protein transduction domains (PTDs) are small peptides with a high content of basic amino acids, and they are responsible for cellular uptake. Many PTDs, including arginine-rich intracellular delivery (AID) peptides, have been shown to transport macromolecules across membranes and into cells. In this study, we demonstrated for the first time that AID peptides could rapidly and efficiently deliver proteins into plant cells in both covalent and noncovalent protein transductions (CNPT) simultaneously. The optimal molecular ratio between an AID peptide carrier and cargo in CNPT was about 3:1. Fluorescence resonance energy transfer (FRET) analysis revealed protein-protein interactions between AID peptide carriers and cargos after CNPT in cells. The possible mechanisms of AID peptides-mediated cellular entry might involve a combination of multiple internalization pathways. Therefore, applications by AID peptide-mediated CNPT may provide a simple and direct transport strategy for delivering two proteins in agricultural systems.

Protein transport in human cells mediated by covalently and noncovalently conjugated arginine-rich intracellular delivery peptides

Generally, biomacromolecules, such as DNA, RNA, and proteins, cannot freely permeate into cells from outside the membrane. Protein transduction domains (PTDs) are peptides containing a large number of basic amino acids that can deliver macromolecules into living cells. Arginine-rich intracellular delivery (AID) peptides are more effective than other PTD peptides at carrying large molecules across cellular membranes. In the present study, we demonstrated that AID peptides are able to deliver cargo proteins into living cells in both covalent and noncovalent protein transductions (CNPT) synchronously. Human A549 cells were treated with a fluorescent protein (FP) that was noncovalently premixed with another AID-conjugated FP, which emitted a different color. After the delivery of carrier AID-FP and cargo FP into cells, the emission and merge of fluorescence were observed and recorded with a confocal microscope, while the internalization efficiency was quantitatively analyzed with a flow cytometer. The optimal molecular ratio between carrier AID-FP and cargo FP for CNPT is about 1:1/3. Fluorescence resonance energy transfer (FRET) assay further confirmed AID-conjugates can physically interact with its cargo FPs in CNPT in cells. Potential uptake mechanisms of CNPT may involve a combination of multiple internalization pathways. After delivery, intracellular distributions of AID-conjugates and FPs may possibly colocalize with lysosomes. These results will facilitate the understanding of multiple mechanisms of PTDs, and provide a powerful tool for simultaneously delivering several proteins or compounds in protein internalization.

Transfection and expression of plasmid DNA in plant cells by an arginine-rich intracellular delivery peptide without protoplast preparation

The delivery and expression of exogenous genes in plant cells have been of particular interest for plant research and biotechnology. Here, we present results demonstrating a simple DNA transfection system in plants. Short arginine-rich intracellular delivery peptide, a protein transduction domain, was capable of delivering plasmid DNA into living plant cells non-covalently. This peptide-mediated DNA delivery conferred several advantages, such as nuclear targeting, non-toxic effect, and ease of preparation without protoplast formulation. Thus, this novel technology shall provide a powerful tool to investigate gene function in vivo, and lay the foundation for the production of transgenic plants in future.

Noncovalent protein transduction in plant cells by macropinocytosis

* Protein delivery across cellular membranes or compartments is primarily limited by low biomembrane permeability. * Many protein transduction domains (PTDs) have previously been generated, and covalently cross-linked with cargoes for cellular internalization. * An arginine-rich intracellular delivery (AID) peptide could rapidly deliver fluorescent proteins or beta-galactosidase enzyme into plant and animal cells in a noncovalent fashion. The possible mechanism of this noncovalent protein transduction (NPT) may involve macropinocytosis. * The NPT via a nontoxic AID peptide provides a powerful tool characterized by its simplicity and quickness to have active proteins function in living cells in vivo. This should be of broad utility for functional enzyme assays and protein therapies in both plant biology research as well as biomedical applications.

Disruption of transforming growth factor beta-regulated laminin receptor function by expression of antisense laminin, a chain RNA in human colon cancer cells

Transforming growth factor beta1 (TGFbeta) simultaneously induces the expression of fibronectin, fibronectin receptor, laminin, and laminin receptor (alpha6beta1 integrin) in the human colon cancer cell line Moser (Int J Cancer, 57:742, 1994). Induction of fibronectin and induction of fibronectin receptor by TGFB are tightly coupled, and disrupting fibronectin induction disrupts the induction of fibronectin receptor and cellular adhesion to fibronectin (J Cellular Physiol, 170:138, 1997). We recently demonstrated the efficacy of using antisense chain-specific laminin RNA expression vectors to disrupt the induction by TGFP of the multichain laminin molecule (J Cellular Physiol, 178:296, 1999). We now show in this report that Moser cells used alpha6 and beta1 integrins to adhere to laminin, and, as is the fibronectin and fibronectin receptor system, disrupting the induction by TGFbeta of the ligand laminin by the expression of antisense laminin A chain RNA disrupted the induction of 125I-laminin binding and cellular adhesion to laminin. Disrupting laminin induction also blocked the induction of alpha6 and beta1 integrin laminin receptor by TGFbeta. We conclude that disrupting the induction of the ligand laminin by TGFbeta disrupts TGFbeta-regulated laminin receptor function by suppressing the induction of alpha6 and beta1 integrins. Therefore, targeted disruption of the ligand laminin may be an effective means in disrupting the function of both the ligand and its receptor in cells that utilize the laminin and laminin receptor system in malignant cell behavior.

Multidrug resistance in leukemic cell line K562/A02 induced by doxorubicin

AIM

To study the mechanism of the development of multidrug resistance in leukemic cells.

METHODS

A human leukemic cell line K562/A02 was established by stepwise increase of concentrations of doxorubicin (Dox) in medium. P-glycoprotein was detected by immunohistochemistry assay. The mdr1 gene expression was measured by RT-PCR. The amplification of mdr1 gene in its genome, and DNA topisomerase II (Top II) gene expression were determined by dot-blot hybridization.

RESULTS

K562/A02 was highly cross-resistant to vincristine (VCR), homoharringtonin (HHT), amsacrine (m-AMSA), daunorubicin (Dau) and etoposide (VP-16), slightly to cytosine arabinoside (Ara-C), but not cisplatin (Cis), methotrexate (MTX) and fluorouracil (5-FU), showing a typical phenotype of MDR. Intracellular accumulation of Dau in K562/A02 was 33% as high as that in K562. P-glycoprotein P-170 was positive. In K562/A02, the mdr1 gene did not amplify, the mdr1 mRNA level was markedly higher, the Top II mRNA level was lower, and glutathione-S-transferase (GST) activity was higher than in K562.

CONCLUSION

mdr1 mRNA was overexpression and thus the encoded P-170 was responsible for MDR in K562/A02 while Top II or GST may play a role in MDR.

[An comparative analysis of the radiographic appearances and the pathologic findings in anthracosilicosis and anthracosilicosis associated with tuberculosis]

Pulmonary tuberculosis is a serious complication of anthracosilicosis and a promoting factor for death. It is very difficult to distinguish the advanced stage of atypical anthracosilicosis from anthracosilicosis associated with tuberculosis by the chest radiograph when the tubercule bacili is negative in sputum, but it is necessary for physician to treat and administrate. In order to probe into the differential diagnosis of these two diseases author made a comparison analysis between the radiographic appearances and the pathological findings of 21 autopsies cases which were clinically diagnosed as anthracosilicosis associated with tuberculosis. There were 8/21 cases (38.1%) of misdiagnosis before the misdiagnosis there were the lack of series observation on the similarities and differences in radiographic appearances between these two diseases and neglect of sputum examination. The main points of clinical differentiation between them were summed up.