[Progress on pharmacokinetic study of antibody-drug conjugates].

Antibody-drug conjugate (ADC) is a new class of therapeutics composed of a monoclonal antibody and small cytotoxin moieties conjugated through a chemical linker. ADC molecules bind to the target antigens expressed on the tumor cell surfaces guided by the monoclonal antibody component. The binding ADC molecules can be internalized and subsequently the toxin moieties can be released within the tumor cells via chemical and/or enzymatic reactions to kill the target cells. The conjugation combines the merits of both components, i.e., the high target specificity of the monoclonal antibody and the highly potent cell killing activity of the cytotoxin moieties. However, such complexities make the pharmacokinetic and metabolic studies of ADCs highly challenging. The major challenges should include characterization of absorption, distribution, metabolism and excretion, investigation of underlying mechanisms, assessment of pharmacokinetic- pharmacodynamic relationship, and analytical method development of ADC drugs. This review will discuss common pharmacokinetic issues and considerations, as well as tools and strategies that can be utilized to characterize the pharmacokinetic and metabolic properties of ADCs.

Endogenous H2O2 Self-Replenishment and Sustainable Cascades Enhance the Efficacy of Sonodynamic Therapy.

Purpose: Sonodynamic therapy (SDT), with its high tissue penetration and noninvasive advantages, represents an emerging approach to eradicating solid tumors. However, the outcomes of SDT are typically hampered by the low oxygen content and immunosuppression in the tumor microenvironment (TME). Accordingly, we constructed a cascade nanoplatform to regulate the TME and improve the anti-tumor efficiency of SDT. Methods: In this study, we rationally design cascade nanoplatform by incorporating immunostimulant hyaluronic acid (HA) and sonosensitizer chlorin e6 (Ce6) on the polydopamine nanocarrier that is pre-doped with platinum nanozymes (designated Ce6/Pt@PDA-HA, PPCH). Results: The cascade reactions of PPCH are evidenced by the results that HA exhibits reversing immunosuppressive that converts M2 macrophages into M1 macrophages in situ, while producing H2O2, and then platinum nanozymes further catalyze the H2O2 to produce O2, and O2 produces abundant singlet oxygen (1O2) under the action of Ce6 and low-intensity focused ultrasound (LIFU), resulting in a domino effect and further amplifying the efficacy of SDT. Due to its pH responsiveness and mitochondrial targeting, PPCH effectively accumulates in tumor cells. Under LIFU irradiation, PPCH effectively reverses immunosuppression, alleviates hypoxia in the TME, enhances reactive oxygen species (ROS) generation, and enhances SDT efficacy for eliminating tumor cells in vivo and in vitro. Meanwhile, an in vivo dual-modal imaging including fluorescence and photoacoustic imaging achieves precise tumor diagnosis. Conclusion: This cascade nanoplatform will provide a promising strategy for enhancing SDT eradication against tumors by modulating immunosuppression and relieving hypoxia.

Loss of MLL Induces Epigenetic Dysregulation of Rasgrf1 to Attenuate Kras-Driven Lung Tumorigenesis.

Menin is necessary for the formation of the menin/mixed lineage leukemia (MLL) complex and is recruited directly to chromatin. Menin is an important tumor suppressor in several cancer types, including lung cancer. Here, we investigated the role of MLL in menin-regulated lung tumorigenesis. Ablation of MLL suppressed KrasG12D-induced lung tumorigenesis in a genetically engineered mouse model. MLL deficiency decreased histone H3 lysine 4 trimethylation (H3K4me3) and subsequently suppressed expression of the Ras protein-specific guanine nucleotide-releasing factor 1 (Rasgrf1) gene. Rasgrf1 was essential for the GTP-bound active state of Kras and the activation of Kras downstream pathways as well as their cancer-promoting activities. MI-3, a small-molecule inhibitor targeting MLL, specifically inhibited the growth of Kras-mutated lung cancer cells in vitro and in vivo with minimal effect on wild-type Kras lung cancer growth. Together, these results demonstrate a novel tumor promoter function of MLL in mutant Kras-induced lung tumorigenesis and further indicate that specific blockade of the MLL-Rasgrf1 pathway may be a potential therapeutic strategy for the treatment of tumors containing Kras mutations. SIGNIFICANCE: Activation of mutant Kras is dependent on MLL-mediated epigenetic regulation of Rasgrf1, conferring sensitivity to small-molecule inhibition of MLL in Kras-driven lung cancer.

Astragaloside IV and Saponins of Rhizoma Polygonati Cure Cyclophosphamide-Induced Myelosuppression in Lung Adenocarcinoma via Down-Regulating miR-142-3p.

Our previous study revealed that Shuanghuang Shengbai granule could cure the myelosuppression induced by cyclophosphamide (CTX) in lung cancer. However, its hematopoietic effects and molecular mechanisms remain not fully understood. Therefore, this study was intended to investigate the effects and the underlying mechanisms of Astragaloside IV (AS) and saponins of rhizoma polygonati (SRP), the two main bioactive ingredients of Shuanghuang Shengbai granule, on CTX-induced myelosuppression. CTX inhibited the proliferation and promoted apoptosis in bone marrow hematopoietic stem cells (BMHSCs), accompanied by the increased expression of miR-142-3p. AS and/or SRP treatment could alleviate CTX-induced cell injury and suppress the expression of miR-142-3p. Over-expression of miR-142-3p partially reversed the therapeutic effect of AS and/or SRP on CTX-induced cell injury in BMHSCs. Further mechanism exploration discovered that HMGB1 was the target gene of miR-142-3p, and miR-142-3p negatively regulated the expression of HMGB1. To further explore the function of AS and/or SRP in vivo, we constructed a lung cancer xenograft combined with CTX-induced myelosuppression mouse model, and we found that AS and SRP remarkably reversed the CTX-induced reduction of white blood cells, bone marrow nucleated cells, and thymus index in vivo and did not affect the chemotherapy effect of lung cancer. Collectively, our results strongly suggested that AS and SRP could improve the hematopoietic function of myelosuppressed lung cancer mice, and their effects may be related to the inhibition of miR-142-3p expression in BMHSCs.

MEN1 deficiency leads to neuroendocrine differentiation of lung cancer and disrupts the DNA damage response.

The MEN1 gene, a tumor suppressor gene that encodes the protein menin, is mutated at high frequencies in neuroendocrine (NE) tumors; however, the biological importance of this gene in NE-type lung cancer in vivo remains unclear. Here, we established an ATII-specific KrasG12D/+/Men1-/- driven genetically engineered mouse model and show that deficiency of menin results in the accumulation of DNA damage and antagonizes oncogenic Kras-induced senescence and the epithelial-to-mesenchymal transition during lung tumorigenesis. The loss of menin expression in certain human primary lung cancers correlates with elevated NE profiles and reduced overall survival.

Abnormal expression of menin predicts the pathogenesis and poor prognosis of adult gliomas.

Several brain tumors is closely related to the disorder of chromatin histone modification, whereas the epigenetic mechanisms of the incidence of highly malignant adult glioma is not yet deeply studied. Deletion or mutation of the MEN1 gene, which encodes the epigenetic regulator menin, specifically induces poorly differentiated neuroendocrine tumors; however, the biological and clinical importance of MEN1 in the nervous system remains poorly understood. Menin expression was robustly activated in 44.4% of adult gliomas. Abnormally high expression of menin was closely related to a shorter median survival time of 20 months, a larger tumor volume and a higher percentage of Ki67 staining. Interestingly, menin expression was also activated in the cytoplasm of tumor cells (38.8%) and was also closely related to the poor prognosis of patients with glioma. Importantly, in a screening of 96 types of small-molecule targeted histone modification regulators, menin inhibitors were found to significantly block the proliferation of adult glioma cells. Our findings confirm that menin is a potential biomarker of poor prognosis in adult gliomas, independent of the WHO grade. Targeting menin may effectively inhibit certain gliomas, and this information provides novel insight into therapeutic strategies for glioma.

Epigenetic alterations contribute to promoter activity of imprinting gene IGF2.

The expression of insulin-like growth factor 2 (IGF2), a classical imprinting gene, didn't completely correlate with its imprinting profiles in hepatocellular carcinoma (HCC). The mechanistic importance of promoter activity in regulation of IGF2 has not been fully clarified. Here we show that histone 3 lysine 4 trimethylation (H3K4me3) modified by menin-MLL complex of IGF2 promoter contributes to promoter activity of IGF2. The strong binding of menin and abundant H3K4me3 at the DNA demethylated P3/4 promoters were observed in Hep3B cells with the robust expression of IGF2. In IGF2-low-expressing HepG2 cells, menin didn't bind to DNA hypermethylated P3/4 regions; however, menin overexpression inhibited DNA methylation and promoted H3K4me3 at the P3/4 as well as IGF2 expression in HepG2. In addition, the H3K4me3 at P3/4 locus was activated in primary HCC specimens with high IGF2 expression. Furthermore, inhibition of the menin/MLL interaction via MI-2/3 reduced IGF2 expression, inhibited the IGF1R-AKT pathway, and significantly repressed HCC with robust expression of IGF2. Taken together, we conclude that H3K4me3 of P3/4 locus mediated by the menin-MLL complex is a novel epigenetic mechanism for releasing IGF2.

Enhancing chemotherapy sensitivity by targeting PcG via the ATM/p53 pathway.

Histone modification and chromatin remodeling are important events in response to DNA damage, and Polycomb group (PcG) proteins, catalyzing H3K27 methylation, are involved. However, the biological function and mechanism of PcG in DNA damage are not fully understood. Additionally, downstream effectors in hepatocellular carcinoma (HCC) remain unclear. The present study investigated the biological and mechanistic roles of PcG in the DNA damage response induced by chemotherapeutic drugs in HCC. It was found that chemotherapy drugs, such as epirubicin (EPB) and mitomycin C (MMC), effectively blocked expression of PcG in p53-wild-type HepG2 cells but not in PLC/PRF5 and Hep3B cells with p53 mutation or deletion. PcG-related target genes involved in DNA damage were identified, including p53, Ataxia telangiectasia mutated (ATM) and Forkhead box O3 (FOXO3). Moreover, targeting PcG-induced p53 expression was associated with increased drug sensitivity in HCC cells. shRNA targeting enhancer of zeste homolog 2 (EZH2) or its inhibitor GSK126 significantly promoted chemotherapeutic drug-induced genotoxicity and increased HepG2 cell chemosensitivity. Mechanistically, chromatin immunoprecipitation (ChIP) assays confirmed that PcG binds to the ATM promoter and inhibits its expression through covalent modification of H3K27me3. Herein, we establish a potential chemotherapy association with GSK126, and the findings suggest this link might represent a new strategy for increasing the sensitivity of HCC to chemotherapeutic agents.

Lentivirus-mediated RNAi knockdown of the gap junction protein, Cx43, attenuates the development of vascular restenosis following balloon injury.

Percutaneous coronary intervention [PCI or percutaneous transluminal coronary angioplasty (PTCA)] has been developed into a mature interventional treatment for atherosclerotic cardiovascular disease. However, the long-term therapeutic effect is compromised by the high incidence of vascular restenosis following angioplasty, and the underlying mechanisms of vascular restenosis have not yet been fully elucidated. In the present study, we investigated the role of the gap junction (GJ) protein, connexin 43 (Cx43), in the development of vascular restenosis. To establish vascular restenosis, rat carotid arteries were subjected to balloon angioplasty injury. At 0, 7, 14 and 2 days following balloon injury, the arteries were removed, and the intimal/medial area of the vessels was measured to evaluate the degree of restenosis. We found that the intimal area gradually increased following balloon injury. Intimal hyperplasia and restenosis were particularly evident at 14 and 28 days after injury. In addition, the mRNA and protein expression of Cx43 was temporarily decreased at 7 days, and subsequently increased at 14 and 28 days following balloon injury, as shown by RT-PCR and western blot analysis. To determine the involvement of Cx43 in vascular restenosis, the lentivirus vector expressing shRNA targeting Cx43, Cx43-RNAi-LV, was used to silence Cx43 in the rat carotid arteries. The knockdown of Cx43 effectively attenuated the development of intimal hyperplasia and vascular restenosis following balloon injury. Thus, our data indicate the vital role of the GJ protein, Cx43, in the development of vascular restenosis, and provide new insight into the pathogenesis of vascular restenosis. Cx43 may prove to be a novel potential pharmacological target for the prevention of vascular restenosis following PCI.

[Study on soil organic carbon pools and turnover characteristics along an elevation gradient in Qilian Mountain].

On the basis of the first order dynamic model combining with the laboratory soil incubation experiment, characteristics of soil organic carbon pools(Csoc), active carbon pools(Ca), slow carbon pools(Cs), passive carbon pools(Cr) and their turnover in Qilian Mountain were studied. It has been showed that the size of Csoc in horizon A and B ranges from 7.606- 89.026 g.kg - and 5.804-84.267 g.kg-1, which shows tendency of "increase-decrease-increase-decrease" with elevation. The size of Cs, Cs, and Cr in horizon A and B under different elevations respectively ranges from 0.180-1.328 g.kg-1, 0.159-1.273 g.kg-1; 3.650-35.173 g.kg-1, 3.703-43. 623 g.kg-1; 3.776-65.298 g.kg-1, 1.942-48. 121 g.kg-1, which incarnates no obvious variation law with elevation. The contents of Csoc, Cr and Cs significantly differ with different elevation gradients. There is no significant difference in the C, content between different elevation gradients. Decomposition rate of Csoc also has no evident change law in elevation. The peak of daily carbon release rate varies with carbon release rate in the whole incubation process, which could be used to present character of SOC turnover rate. It has been also showed that Caand peak of daily carbon release rate have a significant relationship, and they follow the linear relationship. The incubation reveals that Csoc turns over in sequence of Ca, Cs, and Cr,. Polynomial equation presents relation between total SOC release amount and time, of which cubic polynomial has achieved preferable precision(R2 >0.99).

Dual control of Shuanghuang Shengbai granule on upstream and downstream signal modulators of CyclinD-CDK4/6 signaling pathway of cell cycle in Lewis-bearing mice with cyclophosphamide-induced myelosuppression.

BACKGROUND: This study investigated the dual control mechanism of the Shuanghuang Shengbai granule in modulating the cell cycle in Lewis-bearing mice with cyclophosphamide induced myelosuppression. METHODS: Thirty Lewis-bearing mice were randomly grouped into an untreated group, control group, and treated group. Both treated and untreated groups were intraperitoneally injected with cyclophosphamide to produce a myelosuppression model. Mice in the treated group were fed with the Shuanghuang Shengbai granule (40 g/day) for 6 consecutive days. Standard blood tests and the count of bone marrow nuclear cells were performed, and the cell reproductive cycles of bone marrow and tumors were measured in these mice. In addition, the western blot approach was used to measure the upstream activating signals of CyclinD-CDK4/6 such as c-Myc and CDC25A, the upstream suppression signals such as p16INK4a, and the expression of downstream activated signals such as Rb, pRB, and E2F. All of the tested results were validated by reverse transcription quantitative real-time polymerase chain reaction. RESULTS: The results showed that the Shuanghuang Shengbai granule could elevate the count of leukocyte and bone marrow nuclear cells of Lewis-bearing mice with cyclophosphamide induced myelosuppression. It could also stimulate bone marrow cells to move from G0/G1 phases to S phase, accelerating the progress of the cell reproductive cycle and increasing the cell proliferation index. Simultaneously, the Shuanghuang Shengbai granule could also suppress cancer cells moving from G0/G1 phase to S phase, reducing the proliferation index. The tumor weight of Lewis-bearing mice in the treated group was much less than those of the control group. Expression levels of c-Myc, CDC25A, Rb, pRb, and E2F of bone marrow in Shuanghuang Shengbai granule-treated mice was higher compared to the control group, whereas they were lower in the cancer cells. CONCLUSION: The experimental results demonstrate that the Shuanghuang Shengbai granule has dual control on the cell reproductive cycles in cancer cells and bone marrow nuclear cells in Lewis-bearing mice.