Internal enhancement of DNA damage by a novel bispecific antibody-drug conjugate-like therapeutics via blockage of mTOR and PD-L1 signal pathways in pancreatic cancer

Research progress on novel antibody drug conjugates in cancer therapy

Traditional antibody drug conjugates (ADC) combine monoclonal antibodies with cytotoxic drugs to accurately strike cancer cells, but there are still many shortcomings in stability, targeting, efficacy, and safety. Novel ADC, such as bi-specific, site-specific, dual-payload, and pro-drug type ADC, can be optimized by simultaneously binding 2 different antigens or epitopes, selecting more stable linkers, coupling with specific amino acid sites of antibodies, carrying different drug payloads, and adopting prodrug strategies, while retaining the characteristics of traditional ADC. Significantly improving the stability, targeting, efficacy and safety of drugs can better meet the needs of clinical treatment. Novel ADC will play a more important role in cancer treatment in the future. Discussing the progress of novel ADC in cancer treatment and analyzing their advantages and challenges can provide theoretical support for the development of anti-cancer strategies and provide directions for drug research and development.

An EGFR/HER2-targeted conjugate sensitizes gemcitabine-sensitive and resistant pancreatic cancer through different SMAD4-mediated mechanisms

Chemoresistance limits its clinical implementation for pancreatic ductal adenocarcinoma (PDAC). We previously generated an EGFR/HER2 targeted conjugate, dual-targeting ligand-based lidamycin (DTLL), which shows a highly potent antitumor effect. To overcome chemoresistance in PDAC, we aim to study DTLL efficacy when combined with gemcitabine and explore its mechanisms of action. DTLL in combination with gemcitabine show a superior inhibitory effect on the growth of gemcitabine-resistant/sensitive tumors. DTLL sensitizes gemcitabine efficacy via distinct action mechanisms mediated by mothers against decapentaplegic homolog 4 (SMAD4). It not only prevents neoplastic proliferation via ATK/mTOR blockade and NF-κB impaired function in SMAD4-sufficient PDACs, but also restores SMAD4 bioactivity to trigger downstream NF-κB-regulated signaling in SMAD4-deficient tumors and to overcome chemoresistance. DTLL seems to act as a SMAD4 module that normalizes its function in PDAC, having a synergistic effect in combination with gemcitabine. Our findings provide insight into a rational SMAD4-directed precision therapy in PDAC.

Chemoresistance is a main limitation for the treatment of pancreatic ductal adenocarcinoma (PDAC). Here, the authors show that an antibody drug conjugate-like compound targeting both EGFR and HER2 overcomes gemcitabine resistance in PDAC preclinical models by mechanisms involving the tumour suppressor SMAD4.

An efficient curriculum learning-based strategy for molecular graph learning

Computational methods have been widely applied to resolve various core issues in drug discovery, such as molecular property prediction. In recent years, a data-driven computational method-deep learning had achieved a number of impressive successes in various domains. In drug discovery, graph neural networks (GNNs) take molecular graph data as input and learn graph-level representations in non-Euclidean space. An enormous amount of well-performed GNNs have been proposed for molecular graph learning. Meanwhile, efficient use of molecular data during training process, however, has not been paid enough attention. Curriculum learning (CL) is proposed as a training strategy by rearranging training queue based on calculated samples' difficulties, yet the effectiveness of CL method has not been determined in molecular graph learning. In this study, inspired by chemical domain knowledge and task prior information, we proposed a novel CL-based training strategy to improve the training efficiency of molecular graph learning, called CurrMG. Consisting of a difficulty measurer and a training scheduler, CurrMG is designed as a plug-and-play module, which is model-independent and easy-to-use on molecular data. Extensive experiments demonstrated that molecular graph learning models could benefit from CurrMG and gain noticeable improvement on five GNN models and eight molecular property prediction tasks (overall improvement is 4.08%). We further observed CurrMG’s encouraging potential in resource-constrained molecular property prediction. These results indicate that CurrMG can be used as a reliable and efficient training strategy for molecular graph learning.

Availability: The source code is available in https://github.com/gu-yaowen/CurrMG.

Anticancer Activity of Urease Mimetic Cobalt (III) Complexes on A549-Lung Cancer Cells: Targeting the Acidic Microenvironment

Tumour cells maintain a local hypoxic and acidic microenvironment which plays a crucial role in cancer progression and drug resistance. Urease is a metallohydrolases that catalyses the hydrolysis of urea into ammonia and carbon dioxide, causing an abrupt increase of pH. This enzymatic activity can be employed to target the acidic tumour microenvironment. In this study, we present the anticancer activities of urease mimetic cobalt (III) complexes on A549 cells. The cells were treated with different doses of cobalt (III) complexes to observe the cytotoxicity. The change in cellular morphology was observed using an inverted microscope. The cell death induced by these complexes was analysed through ATP proliferation, LDH release and caspase 3/7 activity. The effect of extracellular alkalinization by the cobalt (III) complexes on the efficacy of the weakly basic drug, doxorubicin (dox) was also evaluated. This combination therapy of dox with cobalt (III) complexes resulted in enhanced apoptosis in A549 cells, as evidenced by elevated caspase 3/7 activity in treated groups. The study confirms the urease mimicking anticancer activity of cobalt (III) complexes by neutralizing the tumour microenvironment. This study will motivate the applications of transition metal-based enzyme mimics in targeting the tumour microenvironment for effective anticancer treatments.

A Simple and Efficient Method to Generate Dual Site-Specific Conjugation ADCs with Cysteine Residue and an Unnatural Amino Acid

Antibody-drug conjugates (ADCs) are complex pharmaceutical molecules that combine monoclonal antibodies with biologically active drugs through chemical linkers. ADCs are designed to specifically kill disease cells by utilizing the target specificity of antibodies and the cytotoxicity of chemical drugs. However, the traditional ADCs were only applied to a few disease targets because of some limitations such as the huge molecular weight, the uncontrollable coupling reactions, and a single mechanism of action. Here we report a simple, one-pot, successive reaction method to produce dual payload conjugates with the site-specifically engineered cysteine and p-acetyl-phenylalanine using Herceptin (trastuzumab), an anti-HER2 antibody drug widely used for breast cancer treatment, as a tool molecule. This strategy enables antibodies to conjugate with two mechanistically distinct cytotoxic drugs through different functional groups sequentially, therefore, rendering the newly designed ADCs with functional diversity and the potential to overcome drug resistance and enhance the therapeutic efficacy.

LncRNA FGD5-AS1 promotes the malignant phenotypes of ovarian cancer cells via targeting miR-142-5p

Long non-coding RNAs (lncRNAs) have been reported to participate in regulating gene expression and are related to tumor progression. FGD5 antisense RNA 1 (FGD5-AS1) facilitates the progression of various tumors. However, the expression and function of FGD5-AS1 in ovarian cancer (OC) and its mechanism of action are not yet clear. Real-time polymerase chain reaction (RT-PCR) was employed to explore the expression levels of FGD5-AS1 and miR-142-5p in OC. The relationship between the expression of FGD5-AS1 and clinicopathological indicators of OC patients was analyzed by χ² test. CCK-8 assay, BrdU assay, and Transwell assay were carried out to detect cell proliferation, migration, as well as invasion, respectively. Subcutaneous tumorigenesis experiment and lung metastasis model were used to examine the biological effects of FGD5-AS1 in OC in vivo. Dual luciferase reporter gene assay or RIP experiment was employed to explore the targeting relationship between FGD5-AS1 and miR-142-5p, as well as miR-142-5p and PD-L1 3'UTR. First, we found that FGD5-AS1 was markedly up-regulated in OC. Moreover, its high expression level was associated with positive local lymph node metastasis and higher T stage in OC patients. Gain-of-function and loss-of-function assays demonstrated that FGD5-AS1 facilitated the proliferation, migration, as well as invasion of OC cells. Mechanistically, it was revealed that FGD5-AS1 targeted miR-142-5p to repress its expression and function. Furthermore, miR-142-5p has a binding site for 3' UTR of PD-L1, and FGD5-AS1 could positively regulate PD-L1 expression via repressing miR-142-5p. The present study reports that FGD5-AS1/miR-142-5p/PD-L1 axis is involved in regulating OC progression.

PD-L1 upregulation accompanied with epithelial-mesenchymal transition attenuates sensitivity to ATR inhibition in p53 mutant pancreatic cancer cells

Pancreatic cancer is a highly progressive malignant tumor for which there is a critical unmet need for novel therapeutic strategies. A previous study of the authors indicated that VE-821, a selective inhibitor of the ataxia-telangiectasia-mutated and rad3-related protein (ATR), has antitumor efficacy. In this study, the effect of programmed death ligand 1 (PD-L1) on the sensitivity to VE-821 was investigated in p53 mutant pancreatic cancer cells. These results show that BxPC-3 cells exhibited higher sensitivity to VE-821 than mesenchymal PANC-1 cells, which were more migratory and had higher expressions of PD-L1 and CD44. When VE-821 was applied to two cells, epithelial-to-mesenchymal transition (EMT) was induced in PANC-1 cells with concomitant upregulation of PD-L1 and CD44, while BxPC-3 cells did not manifest these changes. Attenuation of PD-L1 expression suppressed VE-821-induced EMT, inhibited cell migration, and downregulated CD44 expression. Furthermore, PD-L1 inhibition partially reversed the activation of AKT/ERK, enhanced DNA damage, and increased VE-821 sensitivity in PANC-1 cells. Analysis of GEPIA data showed positive correlation of PD-L1 expression with EMT-related transcription factors. Taken together, these results suggest a novel function of PD-L1 in regulating response to ATR inhibition. These data highlight PD-L1 inhibition as a promising target to enhance sensitivity to ATR inhibitors in mesenchymal pancreatic cancer.

Four generations of EGFR TKIs associated with different pathogenic mutations in non-small cell lung carcinoma

Non-small cell lung carcinoma (NSCLC) is a malignant tumour with poor prognosis and high mortality. Platinum-based dual-agent chemotherapy is the main therapeutic regimen for this disease. In recent years, because of the introduction of molecular targeted therapy, various targeted therapeutic agents against epidermal growth factor receptor (EGFR) have been rapidly developed, which has become a research hotspot for NSCLC treatment. Here, we review the latest studies describing the features and types of EGFR pathogenic mutations, currently established EGFR-tyrosine kinase inhibitors from the first to fourth generation, including their action mechanisms, acquired resistance, and clinical applications, and potential challenges and perspectives that current researchers should address.

Internal enhancement of DNA damage by a novel bispecific antibody-drug conjugate-like therapeutics via blockage of mTOR and PD-L1 signal pathways in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a refractory malignant tumor with poor prognosis, limited chemotherapeutic efficacy, and only about 5% of 5-year survival rate. We generated a dual-targeting ligand-based lidamycin (DTLL) to investigate its efficacy against pancreatic cancer after preparing its precursor, DTLP. DTLP was shown specifically binding to EGFR and HER2 on cell surface, followed by endocytosis into cytoplasm of pancreatic cancer cells. DTLL significantly promoted apoptosis and cell cycle arrest at G2/M stages and inhibited cell proliferation. Pancreatic tumors of either MIA-paca-2 cell line-derived (CDX) or patient-derived xenograft (PDX) mouse models were significantly regressed in response to DTLL. It suggested that DTLL might be a highly potent bispecific antibody-drug conjugate (ADC)-like agent for pancreatic cancer therapy. LDM is known to function as an antitumor cytotoxic agent by its induction of DNA damage in cancer cells, therefore, DTLL, as its derivative, also showed similar cytotoxicity. However, we found that DTLL might reverse the AKT/mTOR feedback activation induced by LDM at the first time. The results from both in vitro and in vivo experiments suggested that DTLL enhanced DNA damage via EGFR/HER2-dependent blockage of PI3K/AKT/mTOR and PD-L1 signaling pathways in cancer cells, leading to the inhibition of cell proliferation and immunosurveillance escape from pancreatic tumor. Our studies on DTLL functional characterization revealed its novel mechanisms on internal enhancement of DNA damage and implied that DTLL might provide a promising targeted therapeutic strategy for pancreatic cancer.