HER2-overexpressing Cancer Cells Research Articles

Abstract 355: A novel anti-HER2 antibody that displays superior synergetic effects in Trastuzumab mediated HER2-overexpressing tumor arrest

Abstract The majority of patients with metastatic breast cancer on Trastuzumab, an anti-HER2 monoclonal antibody, generally develop resistance to the drug within a year after initiation of the treatment. Therefore, there is an unmet need for a novel agent to treat HER2 overexpressing breast cancers. Here we described a novel anti-HER2 humanized monoclonal antibody, 19H6-hu, which binds to HER2 ECD with high affinity and could inhibit the proliferation of multiple HER2-overexpressing cancer cell lines as a single agent, though, to a lesser degree when compared to Trastuzumab alone. Interestingly, when in combination with Trastuzumab, 19H6-hu exhibited much stronger potency in inhibition of BT474, N87 and SKBR3 cell growth relative to that of Perjeta in combination with Trastuzumab as well as in suppression of tumor growth in vivo when compared to Trastuzumab alone. Alanine scanning demonstrated that the antibody binds to an alpha-helix located within the domain III and in proximity to the domain IV of HER2 ECD, which is different from the known binding sites of Trastuzumab and Perjeta. Western blotting further confirmed that 19H6-hu in combination with Trastuzumab is more efficacious in blocking phosphorylation of ERK and phosphorylation of HER2 at Y1248 when compared to Trastuzumab in combination with Perjeta or applied alone. Thereby, our results highlight the functional variability of HER2 domains and provide a new insight into the design of HER2-targeting agents. Citation Format: Haomin Huang, xuesai zhang, jianhe Chen, Le Zhao, qingrou Li, zhenping zhu. A novel anti-HER2 antibody that displays superior synergetic effects in Trastuzumab mediated HER2-overexpressing tumor arrest [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 355.

Structural insight into a matured humanized monoclonal antibody HuA21 against HER2-overexpressing cancer cells.

HER2, a member of the epidermal growth factor receptor (EGFR) family, has been associated with human breast, ovarian and gastric cancers. Anti-HER2 monoclonal antibodies (mAbs) have demonstrated clinical efficacy for HER2-overexpressing breast cancer. A chimeric antibody chA21 that specifically inhibits the growth of HER2-overexpressing cancer cells both in vitro and in vivo has previously been developed. To reduce a potential human anti-mouse immune response, the humanized antibody HuA21 was developed and was further subjected to affinity maturation by phage display on the basis of chA21. Here, the crystal structure of HuA21-scFv in complex with the extracellular domain of HER2 is reported, which demonstrates that HuA21 binds almost the same epitope as chA21 and also provides insight into how substitutions in HuA21 improve the binding affinity compared with chA21, which could facilitate structure-based optimization in the future. Furthermore, the effects of HuA21 variants with constant domains of different lengths were explored and it was noticed that the deletion of constant domain 1 could improve the inhibition efficacy in a cell-proliferation assay, possibly functioning via increased internalization, which might guide the design of other monoclonal antibodies.

Development of a Novel Inhibitory Chimeric Anti-HER2 Monoclonal Antibody.

We have recently produced an inhibitory mouse anti-human HER2 mAb (2A8) which displayed potent anti-tumor activity in combination with trastuzumab. To describe chimerization and functional characterization of 2A8 mAb. The VH and VL genes of 2A8 mAb were amplified from cDNA of the mouse hybridoma, ligated to constant regions of human immunoglobulin, and expressed in CHO cell line. Reactivity with four members of human HER family, the inhibitory effects and antibody-dependent cell cytotoxicity (ADCC) of purified chimeric mAb (c2A8) were assessed by ELISA, XTT, H3-tymidine incorporation and lactate dehydrogenase assays. Inhibition of ERK and AKT downstream signaling pathways by the chimeric antibody were analyzed by Western blotting. Chimeric 2A8 mAb bound to recombinant human HER2 and did not cross-react with the other members of HER family. Moreover, c2A8 was able to recognize HER2-overexpressing cancer cell line and inhibited growth and proliferation of these cells. The binding affinity of c2A8 was comparable to the mouse parental mAb. ADCC and Western blotting results showed that the mouse 2A8 mAb was successfully chimerized and could significantly inhibit phosphorylation of AKT in combination with trastuzumab. The c2A8 mAb is potentially a valuable tool for targeted immunotherapy of HER2 positive cancers.

Molecular targeting of HER2-overexpressing biliary tract cancer cells with trastuzumab emtansine, an antibody-cytotoxic drug conjugate.

Trastuzumab emtansine (T-DM1) provides clinical benefit in breast cancers overexpressing human epidermal growth factor receptor 2 (HER2). However, its efficacy against biliary tract cancers (BTC) has not been evaluated. In this study, the effectiveness of T-DM1 in various BTC cell lines and xenograft models with different levels of HER2 expression was investigated. HER2 expression status in xenografts and patient tissue microarrays was assessed by immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH). Cell-surface HER2 expression levels and cell growth inhibition in response to T-DM1 were examined in 17 BTC cell lines. The antitumor activity of T-DM1 was evaluated in four xenograft mouse models with different levels of HER2 expression. The effects of T-DM1 on HER2 signaling, antibody-dependent cell-mediated cytotoxicity (ADCC), cell cycle, and apoptosis were assessed in vitro. Cell-surface expression of HER2 was observed in both gallbladder carcinoma and cholangiocarcinoma tissues. The anti-proliferative activity of T-DM1 was higher in BTC cell lines and breast cancer cell lines with higher levels of HER2 expression. The HER2 status (IHC score|HER2-to-CEP17 ratio by FISH testing) of each BTC xenograft was 3 +|8.3 for KMCH-1, 2 +|4.7 for Mz-ChA-1, 1 +/0|1.4 for OCUG-1, and 0|1.1 for KKU-100, and T-DM1 showed antitumor activity in proportion to the HER2 status. T-DM1 inhibited HER2 signaling and induced ADCC, mitotic arrest, and apoptosis in KMCH-1 cells. T-DM1 exhibited preclinical activity in HER2-overexpressing BTC. Further evaluation in clinical studies is warranted.

Mechanism of action of the trastuzumab biosimilar CT-P6

ABSTRACT Objectives: Therapeutic monoclonal antibody biosimilars are expected to help reduce the sizeable economic burden of targeted treatments. Trastuzumab (Herceptin®), a recombinant humanized monoclonal antibody that binds to the extracellular domain of HER2, is approved for use in HER2-overexpressing breast cancer (in both the adjuvant and metastatic settings) and HER2-positive gastric cancer. CT-P6 (Herzuma®) is a biosimilar of trastuzumab, designed to bind with high affinity and specificity to the same HER2 epitope as the reference product. We investigated whether CT-P6 exerts its effects through the same mechanism of action as trastuzumab. Methods: The mechanism of action of CT-P6 and trastuzumab, both as monotherapy and in combination with paclitaxel or pertuzumab, was compared in HER2-overexpressing breast cancer and gastric cancer cell models. Results: We confirmed that CT-P6 functions in a manner similar to trastuzumab by binding to the HER2 receptor, which is central to the effects of trastuzumab in all indications. Conclusions: Collectively, the results of this study show that the mechanisms of action of CT-P6 and trastuzumab are similar in HER2-positive breast cancer and gastric cancer models and, therefore, CT-P6 can be expected to perform similarly in the clinical setting.

Osthole Synergizes With HER2 Inhibitor, Trastuzumab in HER2-Overexpressed N87 Gastric Cancer by Inducing Apoptosis and Inhibition of AKT-MAPK Pathway.

Background and Purpose: Although trastuzumab has shown considerable activity in the treatment of HER2-positive breast and gastric cancers, a significant proportion of patients do not respond to trastuzumab. Recent studies revealed that osthole, an active coumarin isolated from Cnidium monnieri (L.) Cusson possesses potent anti-tumor activity. Here, we for the first time investigated the anti-tumor activity of trastuzumab in combination with osthole in HER2-overexpressing cancers.Materials and Methods: N87 and SK-BR-3 cell lines, which were HER2-overexpressing cancer cells were used in our study. Cell Counting Kit-8 (CCK-8) assay was utilized to test the inhibitory effects of trastuzumab plus osthole. Combination index (CI) values were calculated using the Chou-Talalay method. Fluorescence-Activated Cell Sorter (FACS) assay was used to examine the cell cycle change and apoptosis upon combinatorial treatment. N87 tumor xenografts were established to evaluate in vivo effects of trastuzumab plus osthole. In addition, molecular mechanisms were analyzed by Western blot in vitro and in vivo.Results: As shown in our study, osthole alone exhibited effective anti-tumor activity against HER2-overexpressed N87 gastric cancer cells and SK-BR-3 breast cancer cells, which may be attributed to cell cycle arrest on G2/M phase and apoptosis. More importantly, our data demonstrated that trastuzumab plus osthole was much more potent than either agent alone in inhibiting the growth of N87 cancer cells in vitro and in vivo, which may be partly explained by the enhanced apoptosis upon the combinatorial treatment. Besides these, we also observed a significant decrease on the phosphorylation of AKT and MAPK in N87 cells when treated with trastuzumab plus osthole compared to either agent alone. Further data from N87 tumor xenografts revealed that trastuzumab plus osthole exerted their synergistic effects mainly on AKT signaling pathway.Conclusion: Collectively, these results support the clinical development of combination osthole with trastuzumab for the treatment of HER2-overexpressed gastric cancer.

Design of novel lipidated peptidomimetic conjugates for targeting EGFR heterodimerization in HER2 + cancer

The human epidermal growth factor receptor (EGFR) family is known to be involved in cell signaling pathways. The extracellular domain of EGFR consists of four domains, of which domain II and domain IV are known to be involved in the dimerization process. Overexpression of these receptors is known to play a significant role in heterodimerization of these receptors leading to the development of cancer. We have designed peptidomimetic molecules to inhibit the EGFR heterodimerization interaction that have shown antiproliferative activity and specificity for HER2-positive cancer cell lines. Among these, a peptidomimetic, compound 5, exhibited antiproliferative activity at low nanomolar concentrations in HER2-overexpressing cancer cell lines. To improve the stability of this peptidomimetic, we have designed and synthesized a novel conjugate of peptidomimetic compound 5 with a lipid, stearic acid. The antiproliferative activity of this conjugate was evaluated in HER2-positive cancer cell lines. Results suggested that the conjugate exhibited selective antiproliferative activity in HER2-overexpressing breast and lung cancer cell lines and was able to block HER2:HER3 heterodimerization. Also, the conjugate showed improved stability with a half-life of 5 h in human serum compared to the half-life of 2 h for parent compound 5. The binding affinity of the conjugate to HER2 protein was evaluated by SPR analysis, and the mode of binding of the lipid conjugate to domain IV of HER2 protein was demonstrated by docking analysis. Thus, this novel lipid conjugate can be used to target HER2-overexpressing cancers.

Kahweol inhibits proliferation and induces apoptosis by suppressing fatty acid synthase in HER2-overexpressing cancer cells

Kahweol is a coffee-specific diterpene found in the beans of Coffea arabica and has been reported to demonstrate various biological activities, including anti-inflammatory, antioxidant, and apoptotic properties. In the present study, we examined the molecular mechanism of kahweol in human epidermal growth factor receptor-2 (HER2)-overexpressing breast cancer cells. Kahweol preferentially inhibited cell proliferation and induced cell death through the induction of a caspase 3-dependent pathway in HER2-overexpression breast cancer cell lines. Kahweol treatment substantially reduced the levels of HER2 protein, mRNA, and transcriptional activity in SKBR3 cells. Kahweol exerts its potent anticancer efficacy by the upregulation of polyomavirus enhancer activator 3 (PEA3) and downregulation of activator protein 2 (AP-2) to inhibit aberrantly activated HER2 signaling. Fatty acid synthase (FASN) expression and sterol regulatory element-binding protein-1c (SREBP-1c) activity were downregulated by kahweol. In addition, kahweol lowered the levels of phosphorylated Akt and its downstream targets mammalian target of rapamycin (mTOR) and cyclin D1. Furthermore, we found that blocking Akt signaling through kahweol treatment significantly reduced FASN expression and subsequently suppressed cell proliferation in HER2-overexpressing cancer cells. Overall, this study suggests that kahweol could be a useful adjuvant therapeutic agent in the treatment of HER2-overexpressing breast cancer.

The novel dithiocarbamate, DpdtC suppresses HER2-overexpressed cancer cells by up-regulating NDRG1 via inactivation of HER2-ERK 1/2 signaling

Dithiocarbamate has been tested for its effective anti-tumor activity, but the underlying mechanism remains unclear. We previously prepared a novel diththiocarbamate derivative, DpdtC with an ability of catalase inhibition. Here, we for the first time investigated the growth inhibition effects of DpdtC on HER2-amplified cancer cells and elucidated its mechanism of action. Results showed that DpdtC exerted the potent anti-tumor effects against HER2-overexpressed SK-OV-3 and SK-BR-3 cells, especially on SK-OV-3 cells with a higher NDRG1 level, which was also confirmed in the SK-OV-3 xenograft model. Interestingly, we observed that NDRG1 was up-regulated, while membrane expression of HER2 was regressed in SK-OV-3 cells upon DpdtC treatment. In agreement, silencing endogenous NDRG1 also increased the expression of HER2 in SK-OV-3 cells, while overexpressing NDRG1 decreased HER2 expression in SK-BR-3 cells. Furthermore, our results showed the formation of the EGFR/HER2 heterodimer was attenuated and phosphorylation of ERK1/2 was inhibited in SK-OV-3 cells when treated with DpdtC. Collectively, these observations demonstrated that NDRG1 plays an important role in mediating the inhibition effects of DpdtC in HER2-overexpressed cancer cells via selective targeting of the HER2-ERK1/2 pathway. Hence, our investigation suggests that up-regulation of NDRG1 by DpdtC is a promising therapeutic approach in HER2-overexpressed cancers.

Design of cyclic and d-amino acids containing peptidomimetics for inhibition of protein-protein interactions of HER2-HER3.

HER2 receptors are surface proteins belonging to the epidermal growth factor family of receptors. Their numbers are elevated in breast, lung, and ovarian cancers. HER2-positive cancers are aggressive, have higher mortality rate, and have a poor prognosis. We have designed peptidomimetics that bind to HER2 and block the HER2-mediated dimerization of epidermal growth factor family of receptors. Among these, a symmetrical cyclic peptidomimetic (compound 18) exhibited antiproliferative activity in HER2-overexpressing lung cancer cell lines with IC50 values in the nanomolar concentration range. To improve the stability of the peptidomimetic, d-amino acids were introduced into the peptidomimetic, and several analogs of compound 18 were designed. Among the analogs of compound 18, compound 32, a cyclic, d-amino acid-containing peptidomimetic, was found to have an IC50 value in the nanomolar range in HER2-overexpressing cancer cell lines. The antiproliferative activity of compound 32 was also measured by using a 3D cell culture model that mimics the in vivo conditions. The binding of compound 32 to the HER2 protein was studied by surface plasmon resonance. In vitro stability studies indicated that compound 32 was stable in serum for 48hours and intact peptide was detectable in vivo for 12hours. Results from our studies indicated that 1 of the d-amino acid analogs of 18, compound 32, binds to the HER2 extracellular domain, inhibiting the phosphorylation of kinase of HER2.

DNA-affibody nanoparticles for inhibiting breast cancer cells overexpressing HER2.

In this study, we have prepared a DNA-affibody nanoparticle which mimics a antibody in its ability to specifically target the HER2 receptor. This nanoparticle has a smaller size (95 kDa) than the monoclonal antibody, trastuzumab (150 kDa) and at least two-fold greater activity toward BT474 cells than trastuzumab. The DNA in this nanoparticle structure has two functions, namely as a support to anchor two affibody molecules and as a vehicle to non-covalently bind multiple copies of a small molecule drug for drug delivery. Each DNA-affibody nanoparticle can bind ∼53 molecules of doxorubicin (DOX) to form a complex, which exhibits greater selectivity toward and inhibition of breast cancer cells overexpressing HER2 than doxorubicin does. As expected, the nanoparticle exhibits lesser inhibition of cells expressing HER2 at a low level. Thus, the nanoparticle represents a highly efficacious agent for inhibiting cancer cells which overexpress HER2, but with low toxicity toward normal cells.

A carrier-free dual-drug nanodelivery system functionalized with aptamer specific targeting HER2-overexpressing cancer cells.

Exploration of a green carrier to avoid potential systemic toxicity and the unclear metabolic mechanism of traditional nanocarriers is of high importance for cancer therapy. Hence, we developed a carrier-free nanosystem for co-delivery of dual anti-cancer drugs ursolic acid (UA) and doxorubicin (DOX) using a "green" and simple method. The co-assembled nanodrug was further modified with a HER2 aptamer by electrostatic interactions. The co-assembled dual nanodrug presented a spherical morphology with a uniform size (∼108.9 nm) and in a pH-triggered drug release manner. It made UA sensitize DOX to display synergistic anticancer effects at a low dose of DOX. Further, the aptamer surface decoration improved the intracellular drug retention of UA and DOX to as much as 2-fold in HER2 overexpressing cancer cells. In addition, the in vivo results further proved that the co-assembled nanodrug could significantly inhibit the tumor growth with a little side effects. In a word, this novel carrier-free dual-drug nanodelivery system could be a potential drug candidate for HER2 overexpressing cancer therapy, and UA could be used as a "green" nanocarrier for delivery of hydrophobic drugs and fluorescent dyes in cancer treatment and diagnosis.

Simvastatin inhibits tumor angiogenesis in HER2-overexpressing human colorectal cancer

Overexpression of the HER2 oncogene contributes to tumor angiogenesis, which is an essential hallmark of cancer. Simvastatin has been reported to exhibit antitumor activities in several cancers; however, its roles and molecular mechanismsin the regulation of colorectal angiogenesis remain to be clarified. Here, we show that colon cancer cells express high levels of VEGF, total HER2 and phosphorylated HER2, and simvastatin apparently decreased their expression in HER2-overexpressing colon cancer cells. Simvastatin pretreatment reduced endothelial tube formation in vitro and microvessel density in vivo. Furthermore, simvastatin markedly inhibited tumor angiogenesis even in the presence of heregulin (HRG)-β1 (a HER2 co-activator) pretreatment in HER2+ tumor cells. Mechanistic investigation showed that simvastatin significantly abrogated HER2-induced tumor angiogenesis by inhibiting VEGF secretion. Together, these results provide a novel mechanism underlying the simvastatin-induced inhibition of tumor angiogenesis through regulating HER2/VEGF axis.

Detection of Her2-overexpressing cancer cells using keyhole shaped chamber array employing a magnetic droplet-handling system

An on-chip gene expression analysis compartmentalized in droplets was developed for detection of cancer cells at a single-cell level. The chip consists of a keyhole-shaped reaction chamber with hydrophobic modification employing a magnetic bead-droplet-handling system with a gate for bead separation. Using three kinds of water-based droplets in oil, a droplet with sample cells, a lysis buffer with magnetic beads, and RT-PCR buffer, parallel magnetic manipulation and fusion of droplets were performed using a magnet-handling device containing small external magnet patterns in an array. The actuation with the magnet offers a simple system for droplet manipulation that allows separation and fusion of droplets containing magnetic beads. After reverse transcription and amplification by thermal cycling, fluorescence was obtained for detection of overexpressing genes. For clinical detection of gastric cancer cells in peritoneal washing, the Her2-overexpressing gastric cancer cells spiked within normal cells was detected by gene expression analysis of droplets containing an average of 2.5 cells. Our developed droplet-based cancer detection system manipulated by external magnetic force without pumps or valves offers a simple and flexible set-up for transcriptional detection of cancer cells, and will be greatly advantageous for less-invasive clinical diagnosis and prognostic prediction.

A single-domain antibody-linked Fab bispecific antibody Her2-S-Fab has potent cytotoxicity against Her2-expressing tumor cells.

Her2, which is frequently overexpressed in breast cancer, is one of the most studied tumor-associated antigens for cancer therapy. Anti-HER2 monoclonal antibody, trastuzumab, has achieved significant clinical benefits in metastatic breast cancer. In this study, we describe a novel bispecific antibody Her2-S-Fab targeting Her2 by linking a single domain anti-CD16 VHH to the trastuzumab Fab. The Her2-S-Fab antibody can be efficiently expressed and purified from Escherichia coli, and drive potent cancer cell killing in HER2-overexpressing cancer cells. In xenograft model, the Her2-S-Fab suppresses tumor growth in the presence of human immune cells. Our results suggest that the bispecific Her2-S-Fab may provide a valid alternative to Her2 positive cancer therapy.

Evaluation of anti-HER2 scFv-conjugated PLGA–PEG nanoparticles on 3D tumor spheroids of BT474 and HCT116 cancer cells

Three-dimensional culture cells (spheroids) are one of the multicellular culture models that can be applied to anticancer chemotherapeutic development. Multicellular spheroids more closely mimic in vivo tumor-like patterns of physiologic environment and morphology. In previous research, we designed docetaxel-loaded pegylated poly(D, L-lactide-co-glycolide) nanoparticles conjugated with anti-HER2 single chain antibodies (scFv–Doc–PLGA–PEG) and evaluated them in 2D cell culture. In this study, we continuously evaluate the cellular uptake and cytotoxic effect of scFv–Doc–PLGA–PEG on a 3D tumor spheroid model of BT474 (HER2-overexpressing) and HCT116 (HER2-underexpressing) cancer cells. The results showed that the nanoparticle formulation conjugated with scFv had a significant internalization effect on the spheroids of HER2-overexpressing cancer cells as compared to the spheroids of HER2-underexpressing cancer cells. Therefore, cytotoxic effects of targeted nanoparticles decreased the size and increased necrotic score of HER2-overexpressing tumor spheroids. Thus, these scFv–Doc–PLGA–PEG nanoparticles have potential for active targeting for HER2-overexpressing cancer therapy. In addition, BT474 and HCT116 spheroids can be used as a tumor model for evaluation of targeting therapies.

Preclinical evidence of multiple mechanisms underlying trastuzumab resistance in gastric cancer.

HER2-positive advanced gastric cancer patients frequently develop resistance to trastuzumab through mechanisms still poorly understood. In breast cancer, other members of the HER-family are known to be involved in trastuzumab-resistance, as is overexpression of the scaffold protein IQGAP1. In the present work, we investigated acquired resistance to trastuzumab in gastric cancer experimental models. Trastuzumab-resistant (HR) subclones derived from 3 HER2-overexpressing gastric cancer cells were generated and characterized for alterations in HER2-signaling mechanisms by next-generation sequencing, immunohistochemical, western blot and qRT-PCR techniques, and molecular modeling analysis. All subclones showed a reduced growth rate with respect to parental cell lines but each had a different resistance mechanism. In NCI N87 HR cells, characterized by a marked increase in HER2-signaling pathways with respect to the parental cell line, trastuzumab sensitivity was restored when IQGAP1 expression was silenced. AKG HR subclone showed higher HER3 protein expression than the parental line. High nuclear HER4 levels were observed in KKP HR cells. In conclusion, our study revealed that high IQGAP1 expression leads to resistance to trastuzumab in gastric cancer. Furthermore, 2 new mutations of the HER2 gene that may be involved in acquired resistance were identified in AKG HR and KKP HR subclones.

Antibody targeting facilitates effective intratumoral siRNA nanoparticle delivery to HER2-overexpressing cancer cells.

The therapeutic potential of RNA interference (RNAi) has been limited by inefficient delivery of short interfering RNA (siRNA). Tumor-specific recognition can be effectively achieved by antibodies directed against highly expressed cancer cell surface receptors. We investigated the utility of linking an internalizing streptavidin-conjugated HER2 antibody to an endosome-disruptive biotinylated polymeric nanocarrier to improve the functional cytoplasmic delivery of siRNA in breast and ovarian cancer cells in vitro and in an intraperitoneal ovarian cancer xenograft model in vivo, yielding an 80% reduction of target mRNA and protein levels with sustained repression for at least 96 hours. RNAi-mediated site specific cleavage of target mRNA was demonstrated using the 5′ RLM-RACE (RNA ligase mediated-rapid amplification of cDNA ends) assay. Mice bearing intraperitoneal human ovarian tumor xenografts demonstrated increased tumor accumulation of Cy5.5 fluorescently labeled siRNA and 70% target gene suppression after treatment with HER2 antibody-directed siRNA nanocarriers. Detection of the expected mRNA cleavage product by 5′ RLM-RACE assay confirmed that suppression occurs via the expected RNAi pathway. Delivery of siRNA via antibody-directed endosomolytic nanoparticles may be a promising strategy for cancer therapy.

Peptide-conjugated PEGylated PAMAM as a highly affinitive nanocarrier towards HER2-overexpressing cancer cells

Efficient drug delivery to the tumor cells was carried out with HER2 targeting peptide-conjugated PEGlyted PAMAM.

Highly efficient nuclear delivery of anti-cancer drugs using a bio-functionalized reduced graphene oxide

Targeted drug delivery has become important, attractive and challenging in biomedical science and applications. Anti-HER2 antibody-conjugated poly-l-lysine functionalized reduced graphene oxide (anti-HER2-rGO-PLL) nanocarriers were prepared to efficiently deliver doxorubicin targeting at the nucleus of HER2 over-expressing cancer cells. The polycationic PLL was first covalently grafted to graphene oxide (GO) nanosheets followed by reduction to obtain rGO-PLL with high drug loading and good colloidal stability. The anti-HER2 antibodies were subsequently conjugated to the amino groups of PLL to achieve excellent cell uptake capability. Cellular uptake of anti-HER2-rGO-PLL into MCF7/HER2 cells is significantly higher than that of rGO-PLL due to the specific targeting of anti-HER2 to HER2 overexpressing breast cancer cells. Additionally the anti-HER2-rGO-PLL enables a fast accumulation of DOX inside the nucleus, its subcellular site of action. In vitro cytotoxicity measurements clearly reveal a seven fold improvement in the anticancer efficacy for anti-HER2-rGO-PLL/DOX in comparison to rGO-PLL/DOX. The enhanced anticancer efficacy could be ascribed to the different intracellular DOX distributions resulted from the different internalization routes that are energy-dependent macropinocytosis and energy-independent direct penetration by anti-HER2-rGO-PLL and rGO-PLL, respectively. The results demonstrate that anti-HER2 conjugated rGO-PLL developed is a promising vehicle for efficient nuclear delivery of chemotherapeutic agents to HER2 over-expressing tumours.