In vivo activity of novel anti-ErbB2 antibody chA21 alone and with Paclitaxel or Trastuzumab in breast and ovarian cancer xenograft models

It was well studied that ErbB2 (HER2/p185(her2/neu)) overexpression in human malignant cancers correlates with poor prognosis and chemo-resistance. Although Trastuzumab (Herceptin) has been widely used in patients with ErbB2-overexpressing metastatic breast cancer, many patients either do not respond to Trastuzumab therapy or progress within 1 year of initiating Trastuzumab treatment. Previously, we reported a novel tumor-inhibitory antibody chA21, which recognized ErbB2 extracellular domain with an epitope distinct from other tumor-inhibitory anti-ErbB2 antibodies. Here, we report that chA21 combined with Paclitaxel or Trastuzumab significantly enhances the tumor-inhibition effects on ErbB2-overexpressing breast and ovarian cancer in xenograft mice. Moreover, the study reveals that the effects by chA21 to cause an enhanced inhibition on cancer cell proliferation and angiogenesis was highly associated with the intrinsic ability of chA21 to down-regulate ErbB2 receptor, inhibit downstream MAPK and PI3K-AKT signal transduction and activate natural killer cells. Our findings show that chA21 may represent a unique anti-ErbB2 antibody with potentials as therapeutic candidate alone or combination with other anti-ErbB2 reagents in cancer therapy.     

Activation of AMPK is necessary for killing cancer cells and sparing cardiac cells

ErbB2 targeted therapies represent an attractive strategy in breast cancer. Herceptin, an anti-ErbB2 monoclonal antibody, is an approved treatment for patients with ErbB2-overexpressing breast cancers. ErbB2 signaling can also be blocked using small molecule tyrosine kinase inhibitors, like Lapatinib, that compete with ATP for binding at the ErbB2 catalytic kinase domain. The principal adverse event attributable to Herceptin is cardiac toxicity. Data from clinical trials show that, unlike Herceptin, Lapatinib may have reduced cardiac toxicity. This study was conducted to elucidate pathways which may contribute to cardiac toxicity or survival using Lapatinib and Herceptin. Our results show that treatments directed to ErbB1/2 receptors using GW-2974 (a generic ErbB1/2 inhibitor) activated AMPK, a key regulator in mitochondrial energy production pathways in human cardiac cells and cancer cells. Although Herceptin down-regulates tumor survival pathways, AMPK fails to be activated in tumor and cardiac cells. When treated in combination with TNF-α, a known cytokine associated with cardiac toxicity, GW-2974 protected cardiac cells from cell death whereas Herceptin contributed to TNF-α-induced cellular killing. Since activity of AMPK in cardiac cells is associated with stress induced survival in response to cytokines or energy depletion, cardiac toxicity by Herceptin may be a consequence of failure to induce stress-related survival mechanisms. Thus, the ability to activate AMPK after treatment with tyrosine kinase inhibitors may be a crucial factor for increased efficacy against the tumor and decreased risk of cardiomyopathy.     

The ErbB2-targeting antibody trastuzumab and the small-molecule SRC inhibitor saracatinib synergistically inhibit ErbB2-overexpressing gastric cancer

The anti-ErbB2 antibody trastuzumab has shown significant clinical benefits in ErbB2-overexpressing breast and gastric cancer, but resistance to the drug is common. Here, we investigated the antitumor activity of the combination of trastuzumab and the SRC inhibitor saracatinib in ErbB2-overexpressing trastuzumab-resistant gastric cancer. The ErbB2-overexpressing human gastric cancer cell line NCI-N87 was treated with trastuzumab to obtain the trastuzumab-resistant cell line NCI-N87R. The NCI-N87R cell line showed a marked increase in SRC activity and ErbB signaling compared with the NCI-N87 cell line. Our data demonstrated that trastuzumab plus saracatinib was much more potent than either agent alone in reducing the phosphorylation of ErbB3 and AKT in both NCI-N87 and NCI-N87R gastric cancer cell lines. Trastuzumab and saracatinib synergistically inhibited the in vitro growth of NCI-N87 and NCI-N87R cell lines. Further data showed that combination therapy of trastuzumab with saracatinib resulted in a significant benefit over either agent alone in both NCI-N87 and NCI-N87R xenograft models, suggesting its potential use for treating ErbB2-overexpressing gastric cancer.     

Identification of Anti-ErbB2 Dual Variable Domain Immunoglobulin (DVD-Ig?) Proteins with Unique Activities

Inhibiting ErbB2 signaling with monoclonal antibodies (mAbs) or small molecules is an established therapeutic strategy in oncology. We have developed anti-ErbB2 Dual Variable Domain Immunoglobulin (DVD-Ig) proteins that capture the function of a combination of two anti-ErbB2 antibodies. In addition, some of the anti-ErbB2 DVD-Ig proteins gain the new functions of enhancing ErbB2 signaling and cell proliferation in N87 cells. We further found that two DVD-Ig proteins, DVD687 and DVD688, have two distinct mechanisms of actions in Calu-3 and N87 cells. DVD687 enhances cell cycle progression while DVD688 induces apoptosis in N87 cells. Using a half DVD687, we found that avidity may play a key role in the agonist activity of DVD687 in N87 cells.     

Epitope mapping and structural analysis of an anti-ErbB2 antibody A21: Molecular basis for tumor inhibitory mechanism

Anti-ErbB2 antibodies targeting distinct epitopes can have different biological functions on cancer cells. A21 prepared by surface epitope masking (SEM) method is a tumor-inhibitory anti-ErbB2 monoclonal antibody. Previously we engineered a single chain chimeric antibody chA21 with potential for therapy of ErbB2-overexpressing tumors. Here, we mapped the A21 epitope on ErbB2 extracellular domain (ECD) by screening a combinatorial phage display peptide library, serial subdomain deletion, and mutagenesis scanning. X-ray crystal structure of the A21 scFv fragment at 2.1 A resolution was also determined. A molecular model of Ag-Ab complex was then constructed based on the crystal structures of the A21 scFv and ErbB2 ECD. Some of biological functions of the A21 mAb and its derivative antibodies including their tumor cell growth inhibition and effects on the expression, internalization, and phosphorylation of ErbB2 receptor were also investigated. The results showed that A21 recognized a conformational epitope comprising a large region mostly from ErbB2 extracellular subdomain I with several surface-exposed residues important for the binding affinity. These data provide unique functional properties of A21 that are quite different from two broadly used anti-ErbB2 mAbs, Herceptin and 2C4. It suggested that the A21 epitope may be another valuable target for designing new anti-ErbB2 therapeutics.     

Erk5 Participates in Neuregulin Signal Transduction and Is Constitutively Active in Breast Cancer Cells Overexpressing ErbB2

The four receptor tyrosine kinases of the ErbB family play essential roles in several physiological processes and have also been implicated in tumor generation and/or progression. Activation of ErbB1/EGFR is mainly triggered by epidermal growth factor (EGF) and other related ligands, while activation of ErbB2, ErbB3, and ErbB4 receptors occurs by binding to another set of EGF-like ligands termed neuregulins (NRGs). Here we show that the Erk5 mitogen-activated protein kinase (MAPK) pathway participates in NRG signal transduction. In MCF7 cells, NRG activated Erk5 in a time- and dose-dependent fashion. The action of NRG on Erk5 was dependent on the kinase activity of ErbB receptors but was independent of Ras. Expression in MCF7 cells of a dominant negative form of Erk5 resulted in a significant decrease in NRG-induced proliferation of MCF7 cells. Analysis of Erk5 in several human tumor cell lines indicated that a constitutively active form of this kinase was present in the BT474 and SKBR3 cell lines, which also expressed activated forms of ErbB2, ErbB3, and ErbB4. Treatments aimed at decreasing the activity of these receptors caused Erk5 inactivation, indicating that the active form of Erk5 present in BT474 and SKBR3 cells was due to a persistent positive stimulus originating at the ErbB receptors. In BT474 cells expression of the dominant negative form of Erk5 resulted in reduced proliferation, indicating that in these cells Erk5 was also involved in the control of proliferation. Taken together, these results suggest that Erk5 may play a role in the regulation of cell proliferation by NRG receptors and indicate that constitutively active NRG receptors may induce proliferative responses in cancer cells through this MAPK pathway.     

Resistance to paclitaxel in hepatoma cells is related to static JNK activation and prohibition into entry of mitosis

Hepatocellular carcinoma (HCC) generally shows chemoresistant features to anticancer agents. Paclitaxel has been clinically used in the treatment of various cancers. However, effect of paclitaxel on HCC has not been adequately addressed. Here, we found two categories of hepatoma cells in response to paclitaxel. Paclitaxel effectively decreased the cell viability of SNU475, Hep3B, and SNU387 HCC cells and Chang liver cells (death prone). In contrast, the other five hepatoma cell lines (SNU449, SNU398, SUN368, SNU354, and HepG2 cells) were resistant to paclitaxel (death reluctant). In response to paclitaxel, Bcl-2 was highly phosphorylated in death-prone cells, whereas much less Bcl-2 was phosphorylated in death-reluctant cells. Cotreatment with SP600125, an inhibitor JNK, significantly reduced the phosphorylated Bcl-2 in death-prone cells and caused a significant reduction in cell death. The reduced cell death was due to prohibition into mitotic entry as evidenced by low cyclin B(1)/Cdk1 kinase activity. In death-reluctant cells, inbuild-phospho-JNK levels were high but no longer activated in response to paclitaxel. We found that paclitaxel combined with caffeine or UCN-01, inhibitors of G(2) DNA damage checkpoint, was able to partially overcome resistance to paclitaxel in these cells. Thus our data provide the molecular basis of paclitaxel resistance in hepatoma cells, and appropriate combination therapy may increase treatment efficacy.     

Combining trastuzumab and cetuximab combats trastuzumab-resistant gastric cancer by effective inhibition of EGFR/ErbB2 heterodimerization and signaling

The anti-ErbB2 antibody trastuzumab has currently been approved for ErbB2-positive gastric cancer. Despite the effectiveness of trastuzumab, resistance is common. Thus, there is an urgent need to overcome trastuzumab resistance. Here, we obtain a trastuzumab-resistant cell line, which is derived from the human gastric cancer NCI-N87 cell line, by modeling the development of acquired resistance in patients. Our data show that combining trastuzumab and cetuximab leads to a significant decrease in EGFR/ErbB2 heterodimers and signaling compared with either antibody alone, and the combination results in greater antitumor activity against the trastuzumab-resistant NCI-N87 cell line, both in vitro and in vivo, suggesting that a combined EGFR/ErbB2 inhibition may overcome trastuzumab resistance.     

Novel anti-ErbB3 monoclonal antibodies show therapeutic efficacy in xenografted and spontaneous mouse tumors

The role of the ErbB3 receptor in signal transduction is to augment the signaling repertoire of active heterodimeric ErbB receptor complexes through activating the PI3K/AKT pathway, which in turn promotes survival and proliferation. ErbB3 has recently been proposed to be involved in acquired resistance to tyrosine kinase inhibitors (TKIs), and is therefore a promising new drug cancer target. Since ErbB3 is a kinase defective receptor, it cannot be targeted by small molecule inhibitors, whereas monoclonal antibodies may offer a viable strategy for pharmacological intervention. In this study, we have utilized DNA electroporation (DNA-EP) to generate a set of novel hybridomas directed against human ErbB3, which have been characterized for their biochemical and functional properties and selected for their ability to negatively regulate the ErbB3-mediated signaling pathway. In vitro, the anti-ErbB3 antibodies modulate the growth rate of cancer cells of different origins. In vivo they show antitumoral properties in a xenograft model of human pancreatic tumor and in the ErbB2-driven carcinogenesis genetically engineered mouse model (GEMM) for mammary tumor, the BALB/neuT. Our data confirm that downregulating the ErbB3-mediated signals with the use of anti-ErbB3 monoclonal antibodies is both feasible and relevant for therapeutic purposes and provides new opportunities for novel anti-ErbB3 combinatory strategies for cancer treatment.     

Inhibition of ErbB2 by receptor tyrosine kinase inhibitors causes myofibrillar structural damage without cell death in adult rat cardiomyocytes

Inhibition of ErbB2 (HER2) with monoclonal antibodies, an effective therapy in some forms of breast cancer, is associated with cardiotoxicity, the pathophysiology of which is poorly understood. Recent data suggest, that dual inhibition of ErbB1 (EGFR) and ErbB2 signaling is more efficient in cancer therapy, however, cardiac safety of this therapeutic approach is unknown. We therefore tested an ErbB1-(CGP059326) and an ErbB1/ErbB2-(PKI166) tyrosine kinase inhibitor in an in-vitro system of adult rat ventricular cardiomyocytes and assessed their effects on 1. cell viability, 2. myofibrillar structure, 3. contractile function, and 4. MAPK- and Akt-signaling alone or in combination with Doxorubicin. Neither CGP nor PKI induced cardiomyocyte necrosis or apoptosis. PKI but not CGP caused myofibrillar structural damage that was additive to that induced by Doxorubicin at clinically relevant doses. These changes were associated with an inhibition of excitation-contraction coupling. PKI but not CGP decreased p-Erk1/2, suggesting a role for this MAP-kinase signaling pathway in the maintenance of myofibrils. These data indicate that the ErbB2 signaling pathway is critical for the maintenance of myofibrillar structure and function. Clinical studies using ErbB2-targeted inhibitors for the treatment of cancer should be designed to include careful monitoring for cardiac dysfunction.     

Bigendothelin-1 via p38-MAPK-dependent mechanism regulates adult rat ventricular myocyte contractility in sepsis

We tested the hypothesis that exogenous administration of the ET-1 precursor, bigET-1, would regulate adult rat ventricular myocyte (ARVM) contractility in a p38-mitogen activated protein kinase (p38-MAPK)-dependent mechanism during sepsis. Ventricular myocytes from adult rat hearts (both sham and septic) were stimulated to contract at 0.5 Hz and mechanical properties were evaluated using an IonOptix Myocam system. Immunoblot analysis was used to determine the phosphorylation of p38-MAPK and extracellular signal-regulated kinase 1/2 (ERK1/2). ARVMs were treated with vehicle, bigET-1 and inhibitors for 24 h and then subjected to functional and biochemical estimations. Septic ARVM displayed a distorted cell membrane and irregular network within the cells along with increased cell contractility as evidenced by elevated peak shortening (PS), maximal velocity of shortening (+dL/dt) and relengthening (-dL/dt) in comparison to sham ARVM. BigET-1 treatment caused ARVM enlargement in both sham and sepsis groups. BigET-1 (100 nM) produced an increase in ARVM contractility in sham group as compared to vehicle treatment. However, septic ARVM treated with bigET-1 exhibited unaltered ARVM contractility, and upregulated ET(B) receptors as compared to respective sham group. BigET-1 increased the concentration of ET-1 and upregulated phosphorylation of p38-MAPK but not of ERK1/2 in sham and septic ARVM. Furthermore, inhibition of p38-MAPK by SB203580 (10 microM) increased ARVM contractility in sham but not in sepsis group. BigET-1 reversed SB203580-induced increase in PS in sham group but accentuated it in sepsis group. BigET-1 also reversed SB203580-induced inhibition of p38-MAPK phosphorylation in sham but not in septic ARVM. SB203580 pretreatment followed by bigET-1 administration significantly decreased p38-MAPK phosphorylation and downregulated ET(B) receptor expression as compared to bigET-1 treatment per se in sepsis group but not in sham. We concluded that a bigET-1-induced non-responsive effect on septic ARVM contractile function could be due to upregulation of p38-MAPK phosphorylation and ET(B) receptor expression.     

ErbB2 degradation mediated by the co-chaperone protein CHIP

ErbB2 overexpression contributes to the evolution of a substantial group of human cancers and signifies a poor clinical prognosis. Thus, down-regulation of ErbB2 signaling has emerged as a new anti-cancer strategy. Ubiquitinylation, mediated by the Cbl family of ubiquitin ligases, has emerged as a physiological mechanism of ErbB receptor down-regulation, and this mechanism appears to contribute to ErbB2 down-regulation induced by therapeutic anti-ErbB2 antibodies. Hsp90 inhibitory ansamycin antibiotics such as geldanamycin (GA) induce rapid ubiquitinylation and down-regulation of ErbB2. However, the ubiquitin ligase(s) involved has not been identified. Here, we show that ErbB2 serves as an in vitro substrate for the Hsp70/Hsp90-associated U-box ubiquitin ligase CHIP. Overexpression of wild type CHIP, but not its U-box mutant H260Q, induced ubiquitinylation and reduction in both cell surface and total levels of ectopically expressed or endogenous ErbB2 in vivo, and this effect was additive with that of 17-allylamino-geldanamycin (17-AAG). The CHIP U-box mutant H260Q reduced 17-AAG-induced ErbB2 ubiquitinylation. Wild type ErbB2 and a mutant incapable of association with Cbl (ErbB2 Y1112F) were equally sensitive to CHIP and 17-AAG, implying that Cbl does not play a major role in geldanamycin-induced ErbB2 down-regulation. Both endogenous and ectopically expressed CHIP and ErbB2 coimmunoprecipitated with each other, and this association was enhanced by 17-AAG. Notably, CHIP H260Q induced a dramatic elevation of ErbB2 association with Hsp70 and prevented the 17-AAG-induced dissociation of Hsp90. Our results demonstrate that ErbB2 is a target of CHIP ubiquitin ligase activity and suggest a role for CHIP E3 activity in controlling both the association of Hsp70/Hsp90 chaperones with ErbB2 and the down-regulation of ErbB2 induced by inhibitors of Hsp90.     

ErbB2 receptor tyrosine kinase signaling mediates early demyelination induced by leprosy bacilli

Demyelination is a common pathologic feature in many neurodegenerative diseases including infection with leprosy-causing Mycobacterium leprae. Because of the long incubation time and highly complex disease pathogenesis, the management of nerve damage in leprosy, as in other demyelinating diseases, is extremely difficult. Therefore, an important challenge in therapeutic interventions is to identify the molecular events that occur in the early phase before the progression of the disease. Here we provide evidence that M. leprae-induced demyelination is a result of direct bacterial ligation to and activation of ErbB2 receptor tyrosine kinase (RTK) signaling without ErbB2-ErbB3 heterodimerization, a previously unknown mechanism that bypasses the neuregulin-ErbB3-mediated ErbB2 phosphorylation. MEK-dependent Erk1 and Erk2 (hereafter referred to as Erk1/2) signaling is identified as a downstream target of M. leprae-induced ErbB2 activation that mediates demyelination. Herceptin (trastuzumab), a therapeutic humanized ErbB2-specific antibody, inhibits M. leprae binding to and activation of ErbB2 and Erk1/2 in human primary Schwann cells, and the blockade of ErbB2 activity by the small molecule dual ErbB1-ErbB2 kinase inhibitor PKI-166 (ref. 11) effectively abrogates M. leprae-induced myelin damage in in vitro and in vivo models. These results may have implications for the design of ErbB2 RTK-based therapies for both leprosy nerve damage and other demyelinating neurodegenerative diseases.     

Myocyte contractile activity modulates norepinephrine cytotoxicity and survival effects of neuregulin-1beta

The purpose of this study is to test the hypothesis that mechanical and electrical activity in adult rat ventricular myocytes (ARVM) alters responses to proapoptotic and prosurvival ligands. The effects of electrical stimulation on myocyte survival, stress signaling, response to -adrenergic receptor (-AR)-stimulated apoptosis, and neuregulin-1 (NRG) were examined. Electrical stimulation (6.6 V/cm; 0, 2, and 5 Hz; 2-ms duration; alternating polarity) of ARVM resulted in more than 70% capture. Although ARVM paced for 48 h showed higher mitochondrial uptake of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (P < 0.05, 0 vs. 2 and 5 Hz), electrical stimulation had little effect on cell survival assessed by trypan blue uptake, CPK release, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining. Electrical stimulation for 24 h did not induce stress response (heat shock protein 70, 90) nor stress kinase (Erk, JNK, p38) activation. NRG stimulation of Erk and Akt was similar between paced and quiescent cells. Pacing sensitized myocytes to -AR-stimulated JNK phosphorylation and cell death with 0.1 µM norepinephrine (NE) in paced myocytes causing equivalent cytotoxicity to 10 µM NE in quiescent cells. NRG suppressed -AR-induced apoptosis through a phosphatidylinositol-3-kinase-dependent pathway in both paced and quiescent cells, although it is overwhelmed by high-NE concentration in paced cells. Thus myocyte contractility modulates both NE cytotoxicity as well as the cytoprotective effect of NRG. These results demonstrate the feasibility and importance of using electrically paced cardiomyocytes in primary culture when examining the signaling pathways of cell survival. adult rat ventricular myocytes; apoptosis; -adrenergic receptor; electrical stimulation     

Cell cycle G2/M arrest and activation of cyclin-dependent kinases associated with low-dose paclitaxel-induced sub-G1 apoptosis

Paclitaxel is a potential anti-cancer agent for several malignancies including ovary, breast, and head and neck cancers. This study investigated the kinetics of paclitaxel-induced cell cycle perturbation in two human nasopharyngeal carcinoma (NPC) cell lines, NPC-TW01 and NPC-TW04. NPC cells treated with higher concentrations (0.1 or 1 μM) of paclitaxel showed obvious G2/M arrest and then converted to a cell population with reduced DNA content, which was detected as a sub-G2 peak in the flow cytometric histographs. If a low concentration (5 nM) of paclitaxel was used instead, transient G2/M arrest was observed in NPC cells, which subsequently converted to a sub-G1 form during the treatment period. Internucleosomal fragmentation and chromatin condensation were detectable in these sub-G1 and sub-G2 cells, suggesting that persistent or transient G2/M arrest is a prerequisite step for apoptosis elicited by varying doses of paclitaxel. The levels of cyclins A, B1, D1, E, CDK 1 (CDC 2), CDK 2 and proliferating cell nuclear antigen (PCNA) were unchanged in NPC cells following treatment with any concentration of paclitaxel; however, apoptosis-related cyclin B1-associated CDC 2 kinase was highly activated by paclitaxel even at concentrations as low as 5 nM, which is consistent with the finding that low-dose paclitaxel is also able to induce apoptosis in NPC cells. Activation of cyclin B1-associated CDC 2 kinase seems to be an important G2/M event required for paclitaxel-induced apoptosis, and this activation of cyclin B1/CDC 2 kinase could be attributed to the increased activity of CDK 7 kinase. This revised version was published online in November 2006 with corrections to the Cover Date.     

Intracellular route and mechanism of action of ERB-hRNase, a human anti-ErbB2 anticancer immunoagent

Human anti-ErbB2 immunoRNase with Erbicin fused to HP-RNase (ERB-hRNase) is a fully human immunoRNase made up of human pancreatic RNase fused to a human anti-ErbB2 scFv. It binds selectively with high affinity to ErbB2-positive cells, and specifically inhibits their proliferation, in vitro and in vivo. An investigation of its mechanism of action and its intracellular destination has revealed that ERB-hRNase depends on its RNase activity for cytotoxic action; it reaches the cytosol directly from the endosomal compartment; it is inhibited by the cytosolic RNase inhibitor (cRI), but the levels that ERB-hRNase reaches in the cytosol neutralize cRI, thus inducing cell death by apoptosis.     

MDM2反义寡核苷酸联合紫杉醇对乳腺癌MCF-7细胞株的作用

目的:探讨靶向MDM2反义寡核苷酸(ASON)联合紫杉醇对乳腺癌MCF-7细胞株的影响。方法:合成一段与MDM2 mRNA特异性结合的反义寡核苷酸和与反义寡核苷酸有4个碱基不同的的错义寡核苷酸(MON),脂质体2000介导不同浓度的MDM2ASON转染MCF-7乳腺癌细胞系,转染的乳腺癌细胞通过1μmol/L紫杉醇药物处理后,采用RT-PCR和Western Blot方法检测MDM2 ASON联合紫杉醇的协同作用及对乳腺癌MCF-7细胞株的抑制效率,MTT观察给药后MCF-7细胞的增殖能力和药物敏感性。结果:MDM2反义寡核苷酸联合紫杉醇明显下调MDM2 mRNA及MDM2蛋白表达水平,抑制MCF-7细胞的生长,随着MDM2 ASON浓度的增加,MDM2表达越来越低,协同作用越来越强,呈剂量依赖关系,A500联合紫杉醇的协同作用最明显,MTT显示紫杉醇处理的转染MCF-7细胞增殖抑制率明显增高,A500抑制增殖作用最明显,抑制率达(13.0±0.84)%。结论:不同浓度MDM2 ASON转染后的乳腺癌MCF-7细胞,等浓度紫杉醇处理后,乳腺癌MCF-7细胞MDM2表达明显降低,细胞凋亡增加,,MDM2 ASON联合紫杉醇对MCF-7细胞有协同作用,提高了乳腺癌MCF-7细胞对紫杉醇的药物敏感性。     

Antiangiogenic Therapy with Human Apolipoprotein(a) Kringle V and Paclitaxel in a Human Ovarian Cancer Mouse Model

INTRODUCTION: The present study compared the effect of combination therapy using human apolipoprotein(a) kringle V (rhLK8) to conventional chemotherapy with paclitaxel for human ovarian carcinoma producing high or low levels of vascular endothelial growth factor (VEGF). MATERIALS AND METHODS: Human ovarian carcinoma cells producing high (SKOV3ip1) or low (HeyA8) levels of VEGF were implanted into the peritoneal cavity of female nude mice. Seven days later, mice were randomized into four groups: control (vehicle), paclitaxel [5 mg/kg, weekly intraperitoneal (i.p.) injection], rhLK8 (50 mg/kg, daily i.p. injection), or the combination of paclitaxel and rhLK8. Mice were treated for 4 weeks and examined by necropsy. RESULTS: In mice implanted with SKOV3ip1 cells, rhLK8 treatment had no significant effect on tumor incidence or the volume of ascites but induced a significant decrease in tumor weight compared with control mice. Paclitaxel significantly reduced tumor weight and ascites volume, and combination treatment with paclitaxel and rhLK8 had an additive therapeutic effect. Similarly, in HeyA8 mice, the effect of combination treatment on tumor weight and tumor incidence was statistically significantly greater than that of paclitaxel or rhLK8 alone. Immunohistochemical analysis showed a significant decrease in microvessel density and a marked increase of apoptosis in tumor and tumor-associated endothelial cells in response to combination treatment with paclitaxel and rhLK8. CONCLUSION: Collectively, these results suggest that antiangiogenic therapy with rhLK8 in combination with taxane-based conventional chemotherapy could be effective for the treatment of ovarian carcinomas, regardless of VEGF status.