Non-IL-2-blocking anti-CD25 antibody inhibits tumor growth by depleting Tregs and has synergistic effects with anti-CTLA-4 therapy

CD25, also known as the interleukin-2 receptor α chain (IL-2Rα), is highly expressed on regulatory T cells (Tregs), but relatively lower on effector T cells (Teffs). This makes it a potential target for Treg depletion, which can be used in tumor immunotherapy. However, marketed anti-CD25 antibodies (Basiliximab and Daclizumab) were originally developed as immunosuppressive drugs to prevent graft rejection, because these antibodies can block IL-2 binding to CD25 on Teffs, which in turn destroys the function of Teffs. Recent studies have shown that non-IL-2-blocking anti-CD25 antibodies have displayed exciting antitumor effects. Here, we screened out a non-IL-2-blocking anti-CD25 monoclonal antibody (mAb) 7B7 by hybridoma technology, and confirmed its antitumor activity via depleting Tregs in a CD25 humanized mouse model. Subsequently, we verified that the humanized 7B7, named as h7B7-15S, has comparable activities to 7B7, and that its Treg depletion is further increased when combined with anti-CTLA-4, leading to enhanced remodeling of the tumor immune microenvironment. Moreover, our findings reveal that the Fab form of h7B7-15S has the ability to deplete Tregs, independent of the Fc region. Taken together, our studies expand the application of anti-CD25 in tumor immunotherapy and provide insight into the underlying mechanism.

Antibody-drug conjugates: Recent advances in payloads

Antibody‒drug conjugates (ADCs), which combine the advantages of monoclonal antibodies with precise targeting and payloads with efficient killing, show great clinical therapeutic value. The ADCs' payloads play a key role in determining the efficacy of ADC drugs and thus have attracted great attention in the field. An ideal ADC payload should possess sufficient toxicity, low immunogenicity, high stability, and modifiable functional groups. Common ADC payloads include tubulin inhibitors and DNA damaging agents, with tubulin inhibitors accounting for more than half of the ADC drugs in clinical development. However, due to clinical limitations of traditional ADC payloads, such as inadequate efficacy and the development of acquired drug resistance, novel highly efficient payloads with diverse targets and reduced side effects are being developed. This perspective summarizes the recent research advances of traditional and novel ADC payloads with main focuses on the structure-activity relationship studies, co-crystal structures, and designing strategies, and further discusses the future research directions of ADC payloads. This review also aims to provide valuable references and future directions for the development of novel ADC payloads that will have high efficacy, low toxicity, adequate stability, and abilities to overcome drug resistance.

FTL004, an anti-CD38 mAb with negligible RBC binding and enhanced pro-apoptotic activity, is a novel candidate for treatments of multiple myeloma and non-Hodgkin lymphoma

Anti-CD38 monoclonal antibodies (mAbs), daratumumab, and isatuximab have represented a breakthrough in the treatment of multiple myeloma (MM). Recently, CD38-based mAbs were expected to achieve increasing potential beyond MM, which encouraged us to develop new anti-CD38 mAbs to meet clinical needs. In this study, we developed a novel humanized anti-CD38 antibody, FTL004, which exhibited enhanced pro-apoptotic ability and negligible binding to red blood cells (RBCs). FTL004 presented a better ability to induce direct apoptosis independent of Fc-mediated cross-linking against lymphoma and MM cell lines as well as primary myeloma cells derived from MM patients. For instance, FTL004 induced RPMI 8226 cells with 55% early apoptosis cells compared with 20% in the isatuximab-treated group. Of interest, FTL004 showed ignorable binding to CD38 on human RBCs in contrast to tumor cells, even at concentrations up to 30 μg/mL. Furthermore, with an engineered Fc domain, FTL004 displayed stronger antibody-dependent cellular cytotoxicity (ADCC) against CD38+ malignant cells. In vivo MM and non-Hodgkin lymphoma tumor xenograft models showed that FTL004 possessed an effective anti-tumor effect. Cryo-electron microscopy structure resolved two epitope centers of FTL004 on CD38: one of which was unique while the other partly overlapped with that of isatuximab. Taken together, FTL004 distinguishes it from other CD38 targeting mAbs and represents a potential candidate for the treatment of MM and non-Hodgkin lymphoma.

Design, Synthesis, and Bioevaluation of a Novel Hybrid Molecular Pyrrolobenzodiazepine-Anthracenecarboxyimide as a Payload for Antibody-Drug Conjugate

A novel series of hybrid molecules combining pyrrolobenzodiazepine (PBD) and anthracenecarboxyimide pharmacophores were designed, synthesized, and tested for in vitro cytotoxicity against various cancer cell lines. The most potent compound from this series, 37b3, exhibited a subnanomolar level of cytotoxicity with an IC₅₀ of 0.17-0.94 nM. 37b3 induced DNA damage and led to tumor cell cycle arrest and apoptosis. We employed 37b3 as a payload to conjugate with trastuzumab to obtain the antibody-drug conjugate (ADC) T-PBA. T-PBA maintained its mode of target and internalization ability of trastuzumab. We demonstrated that T-PBA could be degraded through the lysosomal pathway to release the payload 37b3 after internalization. T-PBA showed a powerful killing effect on Her2-positive cancer cells in vitro. Furthermore, T-PBA significantly inhibited tumor growth in gastric and ovarian cancer xenograft mouse models without overt toxicity. Collectively, these studies suggest that T-PBA represents a promising new ADC that deserves further investigation.

Combination Foretinib and Anti-PD-1 Antibody Immunotherapy for Colorectal Carcinoma

Immune checkpoint inhibitors have achieved unprecedented success in cancer immunotherapy. However, the overall response rate to immune checkpoint inhibitor therapy for many cancers is only between 20 and 40%, and even less for colorectal cancer (CRC) patients. Thus, there is an urgent need to develop an efficient immunotherapeutic strategy for CRC. Here, we developed a novel CRC combination therapy consisting of a multiple receptor tyrosine kinase inhibitor (Foretinib) and anti-PD-1 antibody. The combination therapy significantly inhibited tumor growth in mice, led to improved tumor regression without relapse (83% for CT26 tumors and 50% for MC38 tumors) and prolonged overall survival. Mechanistically, Foretinib caused increased levels of PD-L1 via activating the JAK2-STAT1 pathway, which could improve the effectiveness of the immune checkpoint inhibitor. Moreover, the combination therapy remodeled the tumor microenvironment and enhanced anti-tumor immunity by further increasing the infiltration and improving the function of T cells, decreasing the percentage of tumor-associated macrophages (TAMs) and inhibiting their polarization toward the M2 phenotype. Furthermore, the combination therapy inhibited the metastasis of CT26-Luc tumors to the lung in BALB/c mouse by reducing proportions of regulatory T-cells, TAMs and M2 phenotype TAMs in their lungs. This study suggests that a novel combination therapy utilizing both Foretinib and anti-PD-1 antibody could be an effective combination strategy for CRC immunotherapy.

Effective antitumor activity of 5T4-specific CAR-T cells against ovarian cancer cells in vitro and xenotransplanted tumors in vivo

Ovarian cancer is considered to be the most lethal gynecologic malignancy, and despite the development of conventional therapies and new therapeutic approaches, the patient's survival time remains short because of tumor recurrence and metastasis. Therefore, effective methods to control tumor progression are urgently needed. The oncofetal tumor-associated antigen 5T4 (trophoblast glycoprotein, TPBG) represents an appealing target for adoptive T-cell immunotherapy as it is highly expressed on the surface of various tumor cells, has very limited expression in normal tissues, and spreads widely in malignant tumors throughout their development. In this study, we generated second-generation human chimeric antigen receptor (CAR) T cells with redirected specificity to 5T4 (5T4 CAR-T) and demonstrated that these CAR-T cells can elicit lytic cytotoxicity in targeted tumor cells, in addition to the secretion of cytotoxic cytokines, including IFN-γ, IL-2, and GM-CSF. Furthermore, adoptive transfer of 5T4 CAR-T cells significantly delayed tumor formation in xenografts of peritoneal and subcutaneous animal models. These results demonstrate the potential efficacy and feasibility of 5T4 CAR-T cell immunotherapy and provide a theoretical basis for the clinical study of future immunotherapies targeting 5T4 for ovarian cancer.

HeLa Cell-Derived Paclitaxel-Loaded Microparticles Efficiently Inhibit the Growth of Cervical Carcinoma

Aim

Tumor cell-derived microparticles (MP) can function as a targeted delivery carrier for anti-tumor drugs. Here, we aimed to generate paclitaxel-loaded microparticles (MP-PTX) from HeLa cells and examined its therapeutic potential on human cervical carcinoma.

Methods

MP-PTX was generated from HeLa cells by ultraviolet radiation and subsequent centrifugation. The particle size, drug loading rate, and stability of MP-PTX were examined in vitro. Flow cytometry and the MTT assay were performed to test the inhibitory effect of MP-PTX using different cell lines. Immunodeficient mice bearing HeLa cervical carcinoma were treated with 0.9% normal saline, MP, paclitaxel (PTX) (2.5 mg/kg), or MP-PTX (PTX content identical to PTX group) every day for 6 consecutive days. Tumor volume and animal survival were observed. Micro ¹⁸F-FDG PET/CT was performed to monitor the therapeutic efficacy. The proliferation activity of cells and microvessel density in tumor tissues were determined by immunohistochemical staining using Ki-67 and CD31, respectively.

Results

Dynamic laser scattering measurements showed that the particle size of MP-PTX was 285.58 ± 2.95 nm and the polydispersity index was 0.104 ± 0.106. And the particle size of MP-PTX was not change at 4°C for at least one week. More than 1% of PTX in the medium could be successfully encapsulated into HeLa cell-derived MP. When compared with PTX, MP-PTX treatment significantly increased apoptosis of tumor cells and reduced their proliferation. In addition, MP-PTX showed lower toxicity to normal human umbilical vein endothelial cells (HUVEC) than PTX. In vivo studies further demonstrated that MP-PTX treatment significantly inhibited the growth of cervical carcinoma, prolonged the survival of tumor-bearing mice, and reduced the toxicity of PTX. Immunohistochemical staining revealed that MP-PTX treatment led to decreased Ki-67 positive tumor cells and decreased microvessel density in tumor tissues.

Conclusion

Our results demonstrated that HeLa-derived MP-PTX significantly enhanced the anti-cancer effects of PTX with reduced toxicity, which may provide a novel strategy for the treatment of cervical carcinoma.

Opportunities and obstacles of targeted therapy and immunotherapy in small cell lung cancer

Small cell lung cancer (SCLC) is an aggressive malignant tumour which accounts for approximately 13-15% of all newly diagnosed lung cancer cases. To date, platinum-based chemotherapy are still the first-line treatments for SCLC. However, chemotherapy resistance and systemic toxicity limit the long-term clinical outcome of first-line treatment in SCLC. Recent years, targeted therapy and immunotherapy have made great breakthrough in cancer therapy, and researchers aim to exploit both as a single agent or in combination with chemotherapy to improve the survival of SCLC patients, but limited effectiveness and the adverse events remain the major obstacles in the treatment of SCLC. To overcome these challenges for SCLC therapies, prevention and early diagnosis for this refractory disease is very important. At the same time, we should reveal more information about the pathogenesis of SCLC and the mechanism of drug resistance. Finally, new treatment strategies should also be taken into considerations, such as repurposing drug, optimising of targets, combination therapy strategies or prognostic biomarkers to enhance therapeutic effects and decrease the adverse events rates in SCLC patients. This article will review the molecular biology characteristics of SCLC and discuss the opportunities and obstacles of the current therapy for SCLC patients.

Cryptophycin-55/52 based antibody-drug conjugates: Synthesis, efficacy, and mode of action studies

Cryptophycin-52 (CR52), a tubulin inhibitor, exhibits promising antitumor activity in vitro (picomolar level) and in mouse xenograft models. However, the narrow therapeutic window in clinical trials limits its further development. Antibody-drug conjugate (ADC), formed by coupling cytotoxic compound (payload) to an antibody via a linker, can deliver drug to tumor locations in a targeted manner by antibody, enhancing the therapeutic effects and reducing toxic and side effects. In this study, we aim to explore the possibility of CR52-based ADC for tumor targeted therapy. Due to the lack of a coupling site in CR52, its prodrug cryptophycin-55 (CR55) containing a free hydroxyl was synthesized and conjugated to the model antibody trastuzumab (anti-HER2 antibody drug approved by FDA for breast cancer therapy) via the linkers based on Mc-NHS and Mc-Val-Cit-PAB-PNP. The average drug-to-antibody ratios (DARs) of trastuzumab-CR55 conjugates (named T-L1-CR55, T-L2-CR55, and T-L3-CR55) were 3.50, 3.29, and 3.35, respectively. These conjugates exhibited potent cytotoxicity in HER2-positive tumor cell lines with IC₅₀ values at low nanomolar levels (0.58-1.19 nM). Further, they displayed significant antitumor activities at the doses of 10 mg/kg in established ovarian cancer (SKOV3) and gastric cancer (NCI-N87) xenograft models without overt toxicities. Finally, the drug releases were analyzed and the results indicated that T-L3-CR55 was able to effectively release CR55 and further epoxidized to CR52, which may be responsible for its best performance in antitumor activities. In conclusion, our results demonstrated that these conjugates have the potential for tumor targeted therapy, which provides insights to further research the CR55/CR52-based ADC for tumor therapy.

Platelet-rich plasma and regenerative dentistry

Regenerative dentistry is an emerging field of medicine involving stem cell technology, tissue engineering and dental science. It exploits biological mechanisms to regenerate damaged oral tissues and restore their functions. Platelet‐rich plasma (PRP) is a biological product that is defined as the portion of plasma fraction of autologous blood with a platelet concentration above that of the original whole blood. A super‐mixture of key cytokines and growth factors is present in platelet granules. Thus, the application of PRP has gained unprecedented attention in regenerative medicine. The rationale underlies the utilization of PRP is that it acts as a biomaterial to deliver critical growth factors and cytokines from platelet granules to the targeted area, thus promoting regeneration in a variety of tissues. Based on enhanced understanding of cell signalling and growth factor biology, researchers have begun to use PRP treatment as a novel method to regenerate damaged tissues, including liver, bone, cartilage, tendon and dental pulp. To enable better understanding of the regenerative effects of PRP in dentistry, this review describes different methods of preparation and application of this biological product, and provides detailed explanations of the controversies and future prospects related to the use of PRP in dental regenerative medicine.

Targeting of DDR1 with antibody-drug conjugates has antitumor effects in a mouse model of colon carcinoma

DDR1 has been identified as a cancer‐associated receptor tyrosine kinase that is highly expressed in several malignancies relative to normal tissues. Clinically approved multi‐kinase inhibitors, such as nilotinib, inhibit DDR1‐mediated tumor growth in xenograft models, suggesting DDR1 might be a potential target for cancer treatments. Here, we employed an antibody‐based strategy with a novel anti‐DDR1 antibody‐drug conjugate (ADC) for colon carcinoma treatment. We developed T₄H₁₁‐DM4, an ADC targeting DDR1 which carries the tubulin inhibitor payload DM4. Immunohistochemical analysis of a tissue microarray containing 100 colon cancer specimens revealed that DDR1 was highly expressed in 81% of tumor tissues. Meanwhile, high expression of DDR1 was associated with poor survival in patients. In vitro, T₄H₁₁‐DM4 exhibited potent anti‐proliferative activity with half maximal inhibitory concentration (IC₅₀) values in the nanomolar range in a panel of colon cancer cell lines. In vivo, the antitumor efficacy of T₄H₁₁‐DM4 was evaluated in three colon cancer cell lines expressing different levels of DDR1. T₄H₁₁‐DM4 achieved complete tumor regression at doses of 5 and 10 mg·kg⁻¹ in HT‐29 and HCT116 tumor models. Moreover, a correlation between in vivo efficacy of T₄H₁₁‐DM4 and the levels of DDR1 expression on the cell surface was observed. Tumor cell proliferation was caused by the induction of mitotic arrest, indicating that the antitumor effect in vivo was mediated by DM4. In addition, T₄H₁₁‐DM4 was efficacious in oxaliplatin‐resistant colon cancer models. In exploratory safety studies, T₄H₁₁‐DM4 exhibited no overt toxicities when multi‐doses were administered at 10 mg·kg⁻¹ into BALB/c nude mice or when a single dose up to 50 mg·kg⁻¹ was administered into BALB/c mice. Overall, our findings highlight the potential of DDR1‐targeted ADC and may facilitate the development of a new effective therapeutic strategy for colon cancer.

Expression of 5T4 extracellular domain fusion protein and preparation of anti-5T4 monoclonal antibody with high affinity and internalization efficiency

5T4, a membrane protein, is overexpressed in many tumor tissues but rarely expressed in normal tissues. Here, CHO-5T4⁺ cells were generated and served as the antigen to immunize mice. Hybridoma techniques were employed to produce monoclonal antibodies (mAbs). The recombinant protein of human IgG Fc-fused extracellular domain of 5T4 (5T4 ECD-Fc) was obtained from transient expression in HEK293F cells. The fusion protein 5T4 ECD-Fc and CHO-5T4⁺ cells were respectively utilized to screen anti-5T4 antibodies that could bind to the native antigen. In preliminary screening, three hundred and fifty mAbs were obtained. Via surface plasmon resonance and flow cytometry screening, seven anti-5T4 mAbs stood out. Among them, H6 showed a high affinity (K_D = 1.6 × 10^-11 M) and internalization percentage (36% for 1 h and 80% for 4 h). The molecular weight and isoelectric point of H6 were determined by LC-MS and iCIEF. Moreover, the specific reactivity of H6 was demonstrated by western blotting, flow cytometry, and immunohistochemistry, respectively. In conclusion, we produced human recombinant protein of 5T4 extracellular domain and developed high-affinity internalizing monoclonal antibodies which may be applied in the 5T4-targeting ADC therapy and basic research.

A novel 5T4-targeting antibody-drug conjugate H6-DM4 exhibits potent therapeutic efficacy in gastrointestinal tumor xenograft models

5T4, also named as trophoblast glycoprotein, is often upregulated in some cancer cells. Here, we demonstrated that 5T4 was highly expressed in gastric, colorectal, and pancreatic cancer, associated with significantly poor prognosis of gastrointestinal (GI) cancer patients. To search for new targeting drugs for GI cancer, we developed a novel anti-5T4 monoclonal antibody with high affinity and robust internalization ability and conjugated it to the potent microtubule inhibitor DM4 to produce conjugate H6-DM4. This antibody-drug conjugate (ADC) displayed significant cytotoxicity in a panel of GI cancer cell lines with IC50 values in the nanomolar range. H6-DM4 eradicated established GI tumor xenograft models at 2.5 mg/kg or 10 mg/kg without observable toxicity. Further, 5T4 was highly expressed in cancer-initiating cells (CICs) compared with non-CICs in colorectal cancer. In vitro and in vivo, treatment with H6-DM4 exhibited a powerful efficacy on colorectal CICs. Additionally, colorectal cancer cells resistant to platinum were effectively eliminated by H6-DM4. Taken together, our results showed 5T4-positive GI cancer cells, colorectal cancer-initiating cells, and platinum-resistant colorectal cancer cells were potently eliminated by H6-DM4, indicating H6-DM4 may be a potential candidate drug for GI cancer treatment.

Promiximab-duocarmycin, a new CD56 antibody-drug conjugates, is highly efficacious in small cell lung cancer xenograft models

Small cell lung cancer (SCLC) is of a highly invasive and metastatic lung cancer subtype and there had not been effective targeted therapies. CD56, a cell surface marker highly expressed on most SCLC, is a promising therapeutic target for treatment of this aggressive cancer. In this study, we generated a novel anti-CD56 antibody named promiximab, characterized by high affinity, internalization and tumor specificity. Then, the promiximab was conjugated with a potent DNA alkylating agent duocarmycin via reduced interchain disulfides to yield the promiximab-Duocarmycin (promiximab-DUBA) conjugates. Mass spectrometry analysis showed promiximab-DUBA had an average DAR (Drug-to-Antibody Ratio) of about 2.04. In vitro, promiximab-DUBA exerted strong inhibitory effects on SCLC cell lines NCI-H526, NCI-H524 and NCI-H69, with IC50 values of 0.07 nmol/L, 0.18 nmol/L and 0.29 nmol/L, respectively. In vivo antitumor activity, promiximab-DUBA at the dose of 5 mg/kg and 10 mg/kg every three days with a total of three times were sufficient to induce sustained regression of NCI-H526 tumors over control treatment with promiximab. Mostly, no recurrence was observed until 65 days post treatment with promiximab-DUBA. In the NCI-H69 subcutaneous xenograft model, significant inhibition of tumor growth was also observed following administration of promiximab-DUBA at the dose of 5 mg/kg or 10 mg/kg. Moreover, body weight and histopathology of major organs (liver, spleen, heart, lung and kidney) showed no significant changes after treatment of promiximab-DUBA. In conclusion, promiximab-DUBA is highly efficacious in small cell lung cancer xenograft models, and provides a new immunotherapy approach for SCLC.

Therapeutic potential of an anti-HER2 single chain antibody-DM1 conjugates for the treatment of HER2-positive cancer

Antibody-drug conjugates (ADCs) take the advantage of monoclonal antibodies to selectively deliver highly potent cytotoxic drugs to tumor cells, which have become a powerful measure for cancer treatment in recent years. To develop a more effective therapy for human epidermal growth factor receptor 2 (HER2)-positive cancer, we explored a novel ADCs composed of anti-HER2 scFv-HSA fusion antibodies conjugates with a potent cytotoxic drug DM1. The resulting ADCs, T-SA1-DM1 and T-SA2-DM1 (drug-to-antibody ratio in the range of 3.2-3.5) displayed efficient inhibition in the growth of HER2-positive tumor cell lines and the half-maximal inhibitory concentration on SKBR-3 and SKOV3 cells were both at the nanomolar levels in vitro. In HER2-positive human ovarian cancer xenograft models, T-SA1-DM1 and T-SA2-DM1 also showed remarkable antitumor activity. Importantly, three out of six mice exhibited complete remission without regrowth in the high-dose group of T-SA1-DM1. On the basis of the analysis of luminescence imaging, anti-HER2 scFv-HSA fusion antibodies, especially T-SA1, showed strong and rapid tumor tissue penetrability and distribution compared with trastuzumab. Collectively, the novel type of ADCs is effective and selective targeting to HER2-positive cancer, and may be a promising antitumor drug candidate for further studies.

Salidroside alleviates cachexia symptoms in mouse models of cancer cachexia via activating mTOR signalling

BACKGROUND

Cachexia has a devastating impact on survival and quality of life for many cancer patients and contributes to nearly one-third of all cancer deaths; also, it is associated with poor responses to chemotherapy and survival. A better understanding of the underlying mechanisms of cancer-associated cachexia (CAC), coupled with effective therapeutic approaches, will improve management of progressive functional impairment in cancer patients. Salidroside, a phenylpropanoid glycoside in Rhodiola rosea L, has been reported to possess potential anti-fatigue, anti-ageing, and anti-Alzheimer's disease properties. It is widely consumed as a nutritional supplement, but its effects on CAC and the possible mechanism remain a mystery.

METHODS

In the murine models of cachexia induced by CT-26 and Lewis lung carcinoma (LLC) tumour, respectively, main features of CAC were determined after treatment of salidroside or chemotherapy. In vitro experiments were performed using murine C2C12 myotubes, which were treated by tumour necrosis factor-α. Levels of several critical muscle-related signal proteins such as mammalian target of rapamycin (mTOR), p-mTOR, and myosin heavy chain (MyHC) were examined using western blot both in vitro and in vivo.

RESULTS

In the present study, we showed the exciting effect of salidroside on the treatment of CAC. In CT-26 and LLC models, respectively, salidroside treatment could effectively preserve the tumour-free body weight, decrease loss of adipose and gastrocnemius muscles, alleviate tumour burden, and prolong their survival time. Additionally, in combined chemotherapy, salidroside could synergistically enhance the anti-tumour activity of cisplatin, especially decreased or eliminated chemotherapy-induced cachexia. Further analysis demonstrated that salidroside could significantly increase expression of mTOR, p-mTOR, and MyHC in gastrocnemius muscle. Also, results in vitro showed that salidroside could not only obviously increase mTOR, p-mTOR, and MyHC expression in C2C12 myotubes but also effectively rescue their down-regulation induced by tumour necrosis factor-α.

CONCLUSIONS

In the current study, the exciting effect of salidroside on CAC suggested that salidroside supplementation might be a promising approach for a multi-targeted therapy for the treatment of CAC.

Synthesis, characterization and targeting chemotherapy for ovarian cancer of trastuzumab-SN-38 conjugates

Antibody-drug conjugates (ADCs), combining monoclonal antibody with high cytotoxicity chemotherapeutic drug (warhead), have been successfully applied for clinical cancer therapy. Linker technology to select and design linker connecting warhead with antibody, is critical to the success of therapeutic ADCs. In this study, three kinds of linkers were designed to connect SN-38, the bioactive metabolite of the anticancer drug irinotecan (CPT-11), which is 100-1000 times more potent than CPT-11, with the anti-HER2 antibody trastuzumab to prepare three different ADC conjugates (T-SN38 A, B and C). Meanwhile, we compared the anti-ovarian cancer effect of these three T-SN38 conjugates with trastuzumab in vitro and in vivo. Our in vitro results showed that T-SN38 A, B and C (drug-to-antibody ratio, DAR=3.7, 3.2, 3.4) were 2 to 3 times as cytotoxic as SN-38, and the IC50 for these three conjugates on SKOV-3 cell line at 72 h were 5.2 ± 0.3, 4.4 ± 0.7, and 5.1 ± 0.4 nM respectively. In our in vivo studies, T-SN38 conjugates had well targeting ability for tumor tissue and all three of them had much higher anti-ovarian cancer potency than trastuzumab. Among of them, T-SN38 B, which coupled SN-38 with trastuzumab by a carbonate bond, has the best anti-ovarian cancer potency. In conclusion, the novel HER2-targeting ADCs T-SN38 have great potential for HER2-positive ovarian cancer. Moreover, the SN-38-Linkers designed in this study can also be used to connect with other antibodies for the therapy of other cancers.

Establishment and characterization of intraperitoneal xenograft models by co-injection of human tumor cells and extracellular matrix gel

Establishing a feasible intraperitoneal (i.p.) xenograft model in nude mice is a good strategy to evaluate the antitumor effect of drugs in vivo. However, the manipulation of human cancer cells in establishing a stable peritoneal carcinomatosis model in nude mice is problematic. In the present study, the ovarian and colorectal peritoneal tumor models were successfully established in nude mice by co-injection of human tumor cells and extracellular matrix gel. In ovarian tumor models, the mean number tumor nodes was significantly higher in the experimental group (intraperitoneal tumor cell co-injection with ECM gel) compared with the PBS control group on the 30th day (21.0±3.0 vs. 3.6±2.5; P<0.05). The same results were observed in the colorectal peritoneal tumor models on the 28th day. The colorectal peritoneal tumor model was further used to evaluate the chemotherapy effect of irinotecan (CPT-11). The mean weight of peritoneal tumor nodes in CPT-11 treatment group was significantly less than that of the control group (0.81±0.16 vs. 2.18±0.21 g; P<0.05). The results confirmed the value of these i.p. xenograft models in nude mice as efficient and feasible tools for preclinical evaluation.

Phenotypic variation and diversity of Magnolia sprengeri Pamp. in native habitat

The population of Magnolia sprengeri individuals deceased drastically in the late 20th century because of the widespread harvest for traditional Chinese medicinal recipes. In this study, the levels of phenotypic variation and the genetic structure of 2 populations of M. sprengeri were estimated. The phenotypic variation of M. sprengeri characteristics was nonsynchronous, with a coefficient of variation for 37 characters from 9.55-35.87%. The variance stabilizing transformation value ranged from 0.034-52.344%. The variation contribution within the population was greater than the contribution among the population; the among-population rate was 2.864%, while the within-population rate was 15.849%; values of repeatability for among-population and within-population were 0.430 and 0.098, respectively. This indicates that more variation arose from within-population and that population repeatability was much greater than individual repeatability. Variation in the flower organ was greater than that in the leaf organ; this means that vegetative variation was more stable than reproductive variation. Variation in the southern population was greater than that in the northern population.

Preparation of anti-hECSM2 mouse monoclonal antibodies and their application in the analysis of hECSM2 expression

Human endothelial cell-specific molecule 2 (hECSM2) is a novel, recently identified gene, the biological functions of which are still unclear. The aim of this study was to prepare anti-hECSM2 mouse monoclonal antibodies and investigate the endogenous expression of hECSM2 in cell lines and human tissues. Mouse monoclonal antibodies (MAbs) specifically against hECSM2 were prepared using the hybridoma method. Western blot and flow cytometry were used to detect the specificity of the antibodies. Immunofluorescence and immunohistochemistry were used to investigate the endogenous expression of hECSM2 in different kinds of cell lines and human tissues, respectively. Two anti-hECSM2 MAbs secreting hybridomas were selected. Experiments showed that these two antibodies were highly specific to hECSM2 and endogenous hECSM2 was located on the endothelial cell membrane. Our anti-hECSM2 mouse antibodies can be used for Western blot, flow cytometry, and immunohistochemistry study, and can be a valuable tool for investigating the function and distribution of hECSM2.

Comprehensive analysis of expression profile reveals the ubiquitous distribution of PPPDE peptidase domain 1, a Golgi apparatus component, and its implications in clinical cancer

PPPDE peptidase domain 1 (PPPDE1) is a recently identified gene; however, its expression regulation and biological function are unclear. Previous studies have indicated that PPPDE1 is involved in embryogenesis, apoptosis induction and cell cycle regulation. In the present study, we first used an anti-PPPDE1 antibody to determine that endogenous PPPDE1 is located in the Golgi apparatus. Immunohistochemistry (IHC) of mouse embryos indicated that PPPDE1 was markedly distributed in liver, skin, intestinal villi, and muscles, whereas Western blot analysis of mouse mature organs revealed its ubiquitous expression, without an appreciable distinction in protein abundance. Surprisingly, another potential isoform of PPPDE1 with a molecular weight of 18 kD (rather than its predicted molecular weight of 21 kD) was detected in the mouse kidney, testis, and intestine. Moreover, microarrays that were derived from twelve tumor types revealed that PPPDE1 expression was significantly lower in pancreas, stomach, and skin tumors compared with normal tissue from these organs. We specifically and extensively analyzed PPPDE1 expression in clinical samples and observed strong associations between PPPDE1 expression and (i) differentiation grade in pancreatic ductal adenocarcinoma and (ii) T stage in skin squamous cell carcinoma. Our data are the first to reveal the expression profile of PPPDE1 protein and its implications in cancer. These results will contribute to the understanding of the expression regulation and biological functions of PPPDE1 in development and carcinogenesis.

Protective effect of the nitric oxide pathway in L-citrulline renal ischaemia-reperfusion injury in rats

To observe the protective effects of L-citrulline on the renal I/R injury and elucidate the mechanisms involved, 48 rats were randomized into eight groups: Group 1: sham operated; Group 2: I/R (45 min renal ischaemia and 24 h reperfusion); Group 3: I/R + L-citrulline (300 mg/kg, i.g.); Group 4: I/R + L-citrulline (600 mg/kg, i.g.); Group 5: I/R + L-citrulline (900 mg/kg, i.g.); Group 6: I/R + normal saline (NS, i.g.); Group 7: I/R + N sup ω nitro-L-arginine ester (L-NAME, 20 mg/kg, i.p.); Group 8: I/R + L-citrulline (900 mg/kg, i.g.) + L-NAME (20 mg/ kg, i.p.). At the end of the reperfusion period, serum was collected and the kidneys underwent histological and biochemical examinations. Our results showed that pre-treatment with L-citrulline (300, 600, and 900 mg/kg) significantly ameliorated the renal injury caused by I/R. Moreover, L-citrulline prevented induction of lipid peroxidation and increased the activity of superoxide dismutase and the levels of glutathione and nitric oxide. The I/R-induced decreases in total nitric oxide synthase activity, inducible nitric oxide activity, constitutive nitric oxide activity and endothelial nitric oxide protein expression in the renal cortex were significantly prevented. However, the L-citrulline-mediated protection was significantly antagonized by co-administration of L-NAME. These results suggested that L-citrulline administration exhibited significant protection against renal I/R injury. This protective effect, at least in part, via up-regulation of the endothelial nitric oxide protein expression and constitutive nitric oxide synthase activity, maintained production of nitric oxide at the basal level.

Preparation of the thienopyridine derivatives loaded liposomes and study on the effect of compound-lipid interaction on release behavior

The article describes characterization of two liposome formulations containing thienopyridine derivatives, namely TP-58 and TP-67. By preparing the liposomes, the concentration of the two compounds in ultrapure water was increased up to three orders of magnitude. After i.v. administration of the liposomes in rats, the initial compound plasma concentrations were enhanced more than fifty times relative to that after i.g. administration of the compound suspensions. It was found out that the release rate of TP-67 from the liposome both in vitro and in vivo was not significantly different from that of TP-58. TP-58 was more lipophilic than TP-67 according to partition coefficiency, and TP-67 had greater polarity than TP-58 based on polar surface area (PSA). With DSC, it was found out that the interaction magnitude between TP-67 and the lipid bilayer was not significantly different from that between TP-58 and the lipid bilayer, which accounted for the similarity of the two compounds in release rate both in vitro and in vivo. It indicated liposome can be used as a potential carrier for broading the application of TP-58 and TP-67. Interaction between the thienopyridine derivatives and the lipid bilayer is probably the decisive factor for compound release from the liposomes.

Isoliquiritigenin inhibits the growth of multiple myeloma via blocking IL-6 signaling

Previous studies have suggested that isoliquiritigenin (ISL) has anti-carcinogenic activity in several kinds of solid tumors, however, little is known about the effects of ISL on hematologic malignancies. In this study, we investigated the effects of ISL on multiple myeloma (MM) cells both in vitro and in vivo. The results showed that ISL could inhibit the growth of MM cells and induce their apoptosis in time- and dose-dependent manners. ISL exhibited significant anti-tumor activity in MM xenograft models and synergistically enhanced the anti-myeloma activity of adriamycin. Further analysis demonstrated that ISL not only downregulated IL-6 expression but also significantly decreased levels of phosphorylated ERK and STAT3 and could inhibit phosphorylation levels of ERK and STAT3 induced by recombinant human IL-6, which are critical signaling proteins in IL-6 signaling regulation networks. Taken together, our findings suggested that ISL could inhibit the growth of MM via blocking IL-6 signaling and might serve as a promising therapeutic agent for treatment of MM.

Comprehensive transcription analysis of human pathogenic fungus Penicillium marneffei in mycelial and yeast cells

Penicillium marneffei is a dimorphic fungus that responds to changes in temperature. We performed a comparative analysis of gene expression in mycelial- and yeast-phase P. marneffei cells using high-throughput DNA microarrays. A total of 1,884 differentially expressed genes with annotations in the gene ontology (GO) database were identified between P. marneffei mycelial and yeast cells. These differentially expressed genes mainly belong to 18 categories in the organism's ontology, including reproduction, immunity, metabolism, signaling, etc. Bioinformatics suggests that these differentially expressed genes may help explain the resistance to adverse environments and the virulence of P. marneffei. Nine genes from the results of the DNA microarray experiment were selected for further analysis with real-time quantitative PCR to validate the differential expression. Our data provide a global description of the transcriptional response accompanying adaptation to high temperature in yeast.

Proteomic analysis of the interleukin-4 (IL-4) response in hepatitis B virus-positive human hepatocelluar carcinoma cell line HepG2.2.15

Hepatitis B virus (HBV) infection is the leading cause of liver cirrhosis and hepatocellular carcinoma worldwide. In recent decades, significant progress toward understanding the molecular virology and pathogenesis of HBV infection has been made. In addition, multiple treatment modalities have been developed for persons with HBV infection. In the present study, we demonstrated that IL-4 inhibits the expression of hepatitis B surface antigen and hepatitis B e antigen in a HBV stably transfected hepatocellular carcinoma cell line (HepG2.2.15). To reveal the anti-HBV mechanism of IL-4 by proteomics, 2-DE and MS technology were utilized to profile global changes in protein expression in HepG2.2.15 cells after IL-4 treatment. A total of 56 differentially expressed proteins were identified in IL-4-treated HepG2.2.15 cells. To find out the interaction of these changed proteins by bioinformatics, signaling network analysis with the STRING tool showed that the identified proteins are primarily involved in transcription and proteolysis. Taken together, these results offer valuable clues for understanding the molecular mechanisms of the IL-4-mediated anti-HBV response.

Proteomic identification of RhoA as a potential biomarker for proliferation and metastasis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies in the world, and there is an urgent need to discover novel factors that can act as biomarkers for prognostic assessment and therapeutic targets of HCC. In this study, highly purified plasma membrane proteins from clinical tissue samples were obtained using a strategy combining sucrose density gradient centrifugation and subsequent phase partition. Using a two-dimensional gel electrophoresis and MALDI-Q-TOF MS/MS-based proteomics approach, we identified 13 plasma membrane-associated proteins that were differentially expressed in HCC and normal liver tissues. Of those, RhoA was one of the most significantly upregulated proteins in HCC, and its overexpression was confirmed using Western blotting. Immunohistochemistry suggested a link between RhoA expression and poor differentiation and clinicopathologic stage. Suppression of RhoA expression in HepG2 and Hep3B cells by RNA interference led to significant inhibition of cell growth, induction of apoptosis, and a decrease in migration. Our data suggest that RhoA may serve as a potential biomarker and an attractive therapeutic target for HCC.

Proteomic analysis of interstitial fluid in bone marrow identified that peroxiredoxin 2 regulates H(2)O(2) level of bone marrow during aging

Hematopoiesis in bone marrow declines during aging owing to alteration of the hematopoietic niche. However, due to difficult accessibility and other complexities, senescence-related alteration of the hematopoietic niche is largely unknown. The interstitial fluid of bone marrow (IFBM), a pivotal component of the hematopoietic niche, includes soluble secretory factors that are present between bone marrow cells. To characterize the proteomic profile changes of IFBM during aging, we analyzed the IFBMs of young, adult, and senescent rats using 2-DE combined with ESI/MALDI-Q-TOF MS. Finally, 31 differentially expressed proteins involved in multiple biological functions were identified. Peroxiredoxin 2 (Prx2), down-regulated during aging, was further analyzed and demonstrated that it is produced by bone marrow stromal cells. Interestingly, higher levels of hydrogen peroxide (H(2)O(2)) were detected in the bone marrow with lower Prx2 expression. Moreover, exogenous Prx2 reduced the intracellular H(2)O(2) level in bone marrow stromal cells in vitro. Therefore, Prx2 is implied in the regulation of H(2)O(2) production in the bone marrow during aging. Our data characterized the dynamic protein profiles of the bone marrow microenvironment during aging and we provided clues to elucidate the mechanism of creating a low ROS level in the hematopoietic niche.

Proteomic profiling identifies aberrant epigenetic modifications induced by hepatitis B virus X protein

The hepatitis B virus-encoded X (HBx) protein coactivates transcription of a variety of viral and cellular genes and it is believed to play essential roles in viral replication and hepatocarcinogenesis. To examine the pleiotropic effects of HBx protein on host cell protein expression, we utilized 2-DE and MS analysis to compare and identify differentially expressed proteins between a stable HBx-transfected cell line (HepG2-HBx), constitutively expressing HBx, and vector control cells. Of the 60 spots identified as differentially expressed (+/- over 2-fold, p < 0.05) between the two cell lines, 54 spots were positively identified by MS/MS analysis. Several recent studies suggested that HBx was involved in regional hypermethylation of tumor suppressor genes and global hypomethylation of satellite 2 repeats during hepatocarcinogenesis; however, no specific gene has been reported as hypomethylated by HBx. Promoter methylation analysis was examined for those protein spots showing significant alterations, and our results revealed that specific genes, such as aldehyde dehydrogenase 1 (ALDH1), can be hypomethylated by HBx, and two calcium ion-binding proteins, S100A6 and S100A4, were hypermethylated by HBx and could be re-expressed by AZA (DNA methylase inhibitor) treatment. Moreover, via cluster and pathway analysis, we proposed a hypothetical model for the HBx regulatory circuit involving aberrant methylation of retinol metabolism-related genes and calcium homeostasis-related genes. In summary, we profiled proteome alterations between HepG2-HBx and control cells, and found that HBx not only induces regional hypermethylation but also specific hypomethylation of host cell genes.

Prokaryotic expression of a novel mouse pro-apoptosis protein PNAS-4 and application of its polyclonal antibodies

Mouse PNAS-4 (mPNAS-4) has 96% identity with human PNAS-4 (hPNAS-4) in primary sequence and has been reported to be involved in the apoptotic response to DNA damage. However, there have been no studies reported of the biological functions of mPNAS-4. In studies conducted by our group (unpublished data), it was interesting to note that overexpression of mPNAS-4 promoted apoptotic death in Lewis lung carcinoma cells (LL2) and colon carcinoma cells (CT26) of mice both in vitro and in vivo. In our studies, mPNAS-4 was cloned into the pGEX-6P-1 vector with GST tag at N-terminal in Escherichia coli strain BL21(DE3). The soluble and insoluble expression of recombinant protein mPNAS-4 (rmPNAS-4) was temperature-dependent. The majority of rmPNAS-4 was insoluble at 37 degrees C, while it was almost exclusively expressed in soluble form at 20 degrees C. The soluble rmPNAS-4 was purified by one-step affinity purification, using a glutathione Sepharose 4B column. The rmPNAS-4 protein was further identified by electrospray ionization-mass spectrometry analysis. The search parameters of the parent and fragment mass error tolerance were set at 0.1 and 0.05 kDa, respectively, and the sequence coverage of search result was 28%. The purified rmPNAS-4 was further used as immunogen to raise polyclonal antibodies in New Zealand white rabbit, which were suitable to detect both the recombinant and the endogenous mPNAS-4 in mouse brain tissue and LL2 cells after immunoblotting and/or immunostaining. The purified rmPNAS-4 and our prepared anti-mPNAS-4 polyclonal antibodies may provide useful tools for future biological function studies for mPNAS.

A novel pro-apoptosis gene PNAS4 that induces apoptosis in A549 human lung adenocarcinoma cells and inhibits tumor growth in mice

The gene PNAS4 is a high conservative gene that shares high homology of sequence in various organisms from plants to animals. We found overexpression of human PNAS4 induced apoptosis and arrested cell cycle in S phase in A549 human lung adenocarcinoma cells. In C57BL/6 mice model of Lewis lung carcinoma, overexpression of mouse PNAS4 significantly suppressed tumor growth and prolonged survival time through induction of tumor cell apoptosis, exhibiting effective antitumor. Our original investigations in vitro and vivo indicated PNAS4 is a novel pro-apoptosis gene, which could be used as a potential target of cancer biotherapy in future.

Pnas4 is a novel regulator for convergence and extension during vertebrate gastrulation

Recent studies show that human Pnas4 might be tumor associated, while its function remains unknown. Here, we investigate the developmental function of Pnas4 using zebrafish as a model system. Knocking down Pnas4 causes gastrulation defects with a shorter and broader axis, as well as a posteriorly mis-positioned prechordal plate, due to the defective convergence and extension movement. Conversely, over-expression of Pnas4 mRNA leads to an elongated body axis. We further demonstrate that Pnas4 is required cell-autonomously for dorsal convergence but not for anterior migration. In addition, genetic interaction assays indicate that Pnas4 might act in parallel with non-canonical Wnt signal in the regulation of cell movement. Our data suggest that Pnas4 is a key regulator of cell movement during gastrulation.

Comparative proteomics approach to screening of potential diagnostic and therapeutic targets for oral squamous cell carcinoma

This work demonstrates that a comprehensive strategy of proteomics identification combined with further validation and detailed functional analysis should be adopted in the field of cancer biomarker discovery. A comparative proteomics approach was utilized to identify differentially expressed proteins in 10 oral squamous carcinoma samples paired with their corresponding normal tissues. A total of 52 significantly and consistently altered proteins were identified with eight of these being reported for the first time in oral squamous carcinoma. Of the eight newly implicated proteins, RACK1 was chosen for detailed analysis. RACK1 was demonstrated to be up-regulated in cancer at both the mRNA and protein levels. Immunohistochemical examination showed that the enhanced expression of RACK1 was correlated with the severity of the epithelial dysplasia as well as clinical stage, lymph node involvement, and recurrence, which are known indicators of a relatively poor prognosis in oral squamous carcinoma patients. RNA interference specifically targeted to silence RACK1 could initiate apoptosis of oral squamous carcinoma cells. Taken together, the results indicate that RACK1 is up-regulated in oral squamous carcinoma, not only being closely related to cell proliferation and apoptosis but also linked to clinical invasiveness and metastasis in carcinogenesis. The observations suggest that RACK1 may be a potential biomarker for early diagnosis, prognosis, and monitoring in the therapy of oral squamous carcinoma. Further this comprehensive strategy could be used for identifying other differentially expressed proteins that have potential to be candidate biomarkers of oral squamous carcinoma.

A novel pro-apoptosis protein PNAS-4 from Xenopus laevis: cloning, expression, purification, and polyclonal antibody production

Human PNAS-4 was identified as a novel pro-apoptotic protein in mammalian cells. Here we report the cloning, expression, purification, and antibody production of a PNAS-4 homolog (named xPNAS-4) from Xenopus laevis, an extensively used model organism in exploring gene functions during embryonic development. Recombinant histidine-tagged xPNAS-4 protein was expressed in Escherichia coli as insoluble inclusion bodies. The inclusion bodies were subsequently dissolved in 8 M urea and purified to near homogeneity by Ni2+ affinity chromatography. The resulting denatured protein was refolded by stepwise dilution of urea concentration via dialysis. This procedure yielded about 4 mg refolded protein per liter of E. coli culture with a purity of 95%. The purified protein was identified by liquid chromatography-electrospray ionization-quadrupole-time of flight-mass spectrometry (LC-ESI-Q-TOF-MS) and used to raise anti-xPNAS-4 polyclonal antibodies that were suitable for detecting the expression of PNAS-4 in X. laevis embryos by Western blotting. The availability of recombinant protein and specific polyclonal antibodies will provide a valuable tool in studying apoptotic mechanisms of this protein. To our knowledge, this is the first report to demonstrate the presence of PNAS-4 in X. laevis.

Proteomic analysis of liver cancer cells treated with suberonylanilide hydroxamic acid

PURPOSE

Suberonylanilide hydroxamic acid (SAHA) is an orally administered histone deacetylase inhibitor (HDACI) that has shown significant antitumor activity in a variety of tumor cells. To evaluate if SAHA has an activity against liver cancer, and with an aim to identify the altered cellular factors upon SAHA treatment, human HepG2 cancer cell line was used as a model, and proteomic approach was utilized to elucidate the molecular mechanisms underlying SAHA's antitumor activity.

METHODS

Cell growth inhibition was measured by MTT method, and apoptosis was detected by means of flow cytometry analysis and TUNEL assay. Protein expression profiles were analyzed by 2-DE coupled with MALDI-Q-TOF MS/MS analysis.

RESULTS

A total of 55 differentially expressed proteins were visualized by 2-DE and Coomassie Brilliant Blue (CBB) staining. Of these, 34 proteins were identified via MS/MS analysis. Among the identified proteins, six proteins also displayed significant expression changes at earlier time points upon SAHA treatment, and such alterations were further confirmed by semi-quantitative RT-PCR. Together, at both the mRNA and protein levels, SAHA suppressed the expression of reticulocalbin 1 precursor (RCN1), annexin A3 (ANXA3) and heat shock 27 kDa protein 1 (HSP27), while increasing the expression of aldose reductase (AR), triosephosphate isomerase 1 (TPI) and manganese superoxide dismutase (SOD2).

CONCLUSION

SAHA remarkably inhibited proliferation of HepG2 cancer cells, and induced apoptosis in vitro. Using proteomics approaches, a variety of differentially expressed proteins were identified in HepG2 cancer cells before and after treatment with SAHA. This study will enable a better understanding of the molecular mechanisms underlying SAHA-mediated antitumor effects at the protein level.