The Recombinant and Reconstituted Novel Albumin–Lidamycin Conjugate Shows Lasting Tumor Imaging and Intensively Enhanced Therapeutic Efficacy

A new NCL-targeting aptamer-drug conjugate as a promising therapy against esophageal cancer

Esophageal cancer (EC) is one of the most common highly malignant tumors of the digestive system, with a poor prognosis under current treatment regimens. Nucleolin (NCL) is overexpressed in many tumors, and drugs specifically targeting NCL may offer a promising strategy for treating esophageal cancer. Here, we designed and prepared a novel aptamer-conjugated drug targeting NCL by AS1411 aptamer-human serum albumin (HSA)-the apoprotein of lidamycin (LDP)-active enediyne chromophore (AE), in order to achieve targeted treatment of esophageal cancer. The experimental results revealed that AS1411-HSA-LDP effectively binds to esophageal cancer cells and could be efficiently internalized by esophageal cancer cells. In the KYSE520 xenograft tumor nude mouse model, AS1411-HSA-LDP could be targeted and enriched in the tumor location for a long time. AS1411-HSA-LDP-AE exhibited a strong cell-killing activity in esophageal cancer cells, inhibited cell migration and invasion, and induced cell apoptosis. The animal studies confirmed that AS1411-HSA-LDP-AE exhibited a strong anti-tumor effect. These findings suggested that the novel NCL-targeting aptamer-drug conjugate constructed based on lidamycin exhibited a strong anti-tumor effect, providing a promising strategy for the targeted treatment of esophageal cancer.

Natriuretic peptides: Another tool for the management of cancer?

The connection between heart failure (HF) and cancer through multiple pathways such as inflammation, oxidative stress, and neurohormonal activation, among others, is well established. As a consequence, increases in plasma levels of several biomarkers have been described in both disorders. The most consistent information is related to natriuretic peptides (NPs). Although they are known to be produced in the ventricles as a response to myocardial distension, and thus can be useful for the diagnosis and prognosis of HF, and also for the management of chemotherapy-induced myocardial damage, they are also produced by tumour cells. In this regard, increased plasma levels of NPs have been described in patients with multiple malignancies in the absence of volume overload. Natriuretic peptide levels have been shown to correlate directly with the extension of tumours and with poorer outcomes. Moreover, some data indicate that they may help in the detection of subclinical tumours. Given that these peptides have been described to have anti-proliferative and anti-angiogenic effects, a plausible hypothesis is that they may be produced by tumours as a negative feed-back mechanism to avoid tumour progression. This would lead to increased levels of NPs in plasma that could be potentially useful for early detection of malignancies as well as for a prognostic assessment. Nevertheless, since the sample size of many studies published so far is limited, more data are needed to provide consistent data in order to confirm or rule out this hypothesis.

Antitumor efficacy of a recombinant EGFR-targeted fusion protein conjugate that induces telomere shortening and telomerase downregulation

OBJECTIVE

To prepare a recombinant EGFR-targeted fusion protein drug conjugate acting on telomere and telomerase; and evaluate its antitumor efficacy.

METHODS

We prepared a recombinant fusion protein Fv-LDP-D3 which consists of the Fv fragment of an anti-EGFR monoclonal antibody (MAb), the apoprotein of lidamycin (LDP), and the third domain (D3) of human serum albumin (HSA); then generated the conjugate Fv-LDP-D3∼AE by integrating the active enediyne chomophore (AE) of lidamycin. Accordingly, in vitro and in vivo experiments were performed.

RESULTS

As shown, Fv-LDP-D3 specifically bound to EGFR highly-expressing cancer cells and intensely entered K-Ras mutant cells via enhanced macropinocytosis. By in vivo imaging, Fv-LDP-D3 displayed intense accumulation and persistent retention in tumor-site. Furthermore, the conjugate Fv-LDP-D3∼AE displayed highly potent cytotoxicity to cancer cells with IC₅₀ at 0.1 nM level. The conjugate induced telomere shortening and downregulation of telomerase and EGFR pathway related proteins. Fv-LDP-D3∼AE exhibited prominent antitumor efficacy against human colorectal cancer xenograft accompanying with significant increase of serum IFN-β in athymic mice.

CONCLUSION

The recombinant fusion protein conjugate that exhibits the capability of tumor-targeting drug delivery can induce telomere shortening and telomerase downregulation. The investigation may lay the foundation for the development of MAb-HSA domain-based fusion protein drug conjugates.

A recombinant scFv antibody-based fusion protein that targets EGFR associated with IMPDH2 downregulation and its drug conjugate show therapeutic efficacy against esophageal cancer

The present study aimed to evaluate the anti-tumor efficacy of the epidermal growth factor receptor (EGFR)-targeting recombinant fusion protein Fv-LDP-D3 and its antibody-drug conjugate Fv-LDP-D3-AE against esophageal cancer. Fv-LDP-D3, consisting of the fragment variable (Fv) of an anti-EGFR antibody, the apoprotein of lidamycin (LDP), and the third domain of human serum albumin (D3), exhibited a high binding affinity for EGFR-overexpressing esophageal cancer cells, inhibited EGFR phosphorylation and down-regulated inosine monophosphate dehydrogenase type II (IMPDH2) expression. Fv-LDP-D3 was taken up by cancer cells through intensive macropinocytosis; it inhibited the proliferation and induced the apoptosis of esophageal cancer cells. In vivo imaging revealed that Fv-LDP-D3 displayed specific tumor-site accumulation and a long-lasting retention over a 26-day period. Furthermore, Fv-LDP-D3-AE, a pertinent antibody-drug conjugate prepared by integrating the enediyne chromophore of lidamycin into the Fv-LDP-D3 molecule, displayed highly potent cytotoxicity, inhibited migration and invasion, induced apoptosis and DNA damage, arrested cells at G2/M phase, and caused mitochondrial damage in esophageal cancer cells. More importantly, both of Fv-LDP-D3 and Fv-LDP-D3-AE markedly inhibited the growth of esophageal cancer xenografts in athymic mice at well tolerated doses. The present results indicate that Fv-LDP-D3, and Fv-LDP-D3-AE exert prominent antitumor efficacy associated with targeting EGFR, suggesting their potential as promising candidates for targeted therapy against esophageal cancer.

The development of human serum albumin-based drugs and relevant fusion proteins for cancer therapy

Human serum albumin (HSA)-based therapeutics have attracted tremendous attention in the development of anticancer agents. The versatile properties of HSA make HSA-based therapeutics possess improved pharmacokinetics, extended circulation half-life, enhanced efficacy, reduced toxicity, etc. Generally, the HSA-based therapeutics systems can be divided into four categories, i.e. HSA-drug nanoparticles, HSA-drug conjugates, HSA-binding prodrugs, and HSA-based recombinant fusion proteins: the latter mainly include antibody (domain)- and cytokine- fusion proteins. Advances in this area revealed the advantages of HSA-based systems in the development of tumor site-oriented therapeutics, partly referring to the enhanced penetration and retention (EPR) effect and the intensive macropinocytosis. Accordingly, a variety of technical platforms for the design and preparation of HSA-based therapeutics have been reported. Major strategies and directions for the drug development were discussed; those include (1) Tumor-site oriented drug delivery and enhanced drug retention, (2) Tumor-site prodrug release and activation, (3) Cancer cell bound intensive drug internalization, and (4) Tumor microenvironment (TME) directed immunomodulation. Notably, the multimodal HSA-based approach is promising for the development of tumor-oriented therapeutics for cancer therapy.

Modified Natriuretic Peptides and their Potential Role in Cancer Treatment

The natriuretic peptide family (NPs) is a group of natural endocrine hormones, containing a 17-amino acid ring structure connected by disulfide bonds of two cysteines. In this review, the members of the natriuretic peptide family and their corresponding receptors as well as the anti-cancer effects are introduced. Four cardiac hormones of NPs (ANP, VD, KP and LANP) can effectively inhibit the growth of human small cell lung cancer, breast cancer and other tumors and significantly reduce tumor volume in vivo. The in vitro experiments also show that cardiac hormones, CNP and urodilatin can effectively inhibit the growth of most tumor cells. We then further summarized the anti-cancer mechanism of natriuretic peptides. Finally, we introduce several methods that modify natriuretic peptides, leading to enhance their stability and prolong the biological effects of these peptides, which might be helpful for the clinical application in the future. Peptide therapy is a very promising field for cancer treatments since they can induce the death of cancer cells without dramatically affecting normal cells. The synthesis of a useful and stable natriuretic peptide can enhance the effect of cancer treatments and significantly reduce drug resistance and toxicity.

Development of a novel multi-functional integrated bioconjugate that effectively targets K-Ras mutant pancreatic cancer

Folate receptor (FR) overexpression occurs in a variety of cancers, including pancreatic cancer. In addition, enhanced macropinocytosis exists in K-Ras mutant pancreatic cancer. Furthermore, the occurrence of intensive desmoplasia causes a hypoxic microenvironment in pancreatic cancer. In this study, a novel FR-directed, macropinocytosis-enhanced, and highly cytotoxic bioconjugate folate (F)-human serum albumin (HSA)-apoprotein of lidamycin (LDP)-active enediyne (AE) derived from lidamycin was designed and prepared. F-HSA-LDP-AE consisted of four moieties: F, HSA, LDP, and AE. F-HSA-LDP presented high binding efficiency with the FR and pancreatic cancer cells. Its uptake in wild-type cells was more extensive than in K-Ras mutant-type cells. By in vivo optical imaging, F-HSA-LDP displayed prominent tumor-specific biodistribution in pancreatic cancer xenograft-bearing mice, showing clear and lasting tumor localization for 360 h. In the MTT assay, F-HSA-LDP-AE demonstrated potent cytotoxicity in three types of pancreatic cancer cell lines. It also induced apoptosis and caused G2/M cell cycle arrest. F-HSA-LDP-AE markedly suppressed the tumor growth of AsPc-1 pancreatic cancer xenografts in athymic mice. At well-tolerated doses of 0.5 and 1 mg/kg, (i.v., twice), the inhibition rates were 91.2% and 94.8%, respectively (P<0.01). The results of this study indicate that the F-HSA-LDP multi-functional bioconjugate might be effective for treating K-Ras mutant pancreatic cancer.

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We designed and generated a folate receptor-targeted and macropinocytosis-enhanced recombinant protein conjugate.

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F-HSA-LDP displayed highly specific biodistribution and long-lasting tumor accumulation in pancreatic cancer cells.

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F-HSA-LDP-AE induced apoptosis and G2/M cell cycle arrest and markedly suppressed the growth of pancreatic cancer cells.

An albumin‑binding domain and targeting peptide‑based recombinant protein and its enediyne‑integrated analogue exhibit directional delivery and potent inhibitory activity on pancreatic cancer with K‑ras mutation

Efficient enrichment and transmembrane transport of cytotoxic reagents are considered to be effective strategies to increase the efficiency and selectivity of antitumor drugs targeting solid tumors. In the present study, a recombinant protein ABD‑LDP‑Ec consisting of the albumin‑binding domain (ABD), the apoprotein (LDP) of lidamycin (LDM) and an EGFR‑targeting oligopeptide (Ec) was prepared by DNA recombination and bacterial fermentation, and was integrated with the enediyne chromophore (AE) of lidamycin to generate its enediyne‑integrated analogue ABD‑LDP‑Ec‑AE. ABD‑LDP‑Ec exhibited high binding capacity to both albumin and EGFR‑positive pancreatic cancer cells, and was internalized into the cytoplasm through receptor‑mediated endocytosis and albumin‑driven macropinocytosis of K‑ras mutant cells. In animal experiments, ABD‑LDP‑Ec demonstrated notable selective distribution in pancreatic carcinoma xenografts by passive targeting of albumin captured in the blood and was retained in the tumor for 48 h. ABD‑LDP‑Ec and ABD‑LDP‑Ec‑AE exhibited inhibitory activity in cell proliferation and AsPC‑1 xenograft growth, and ABD‑LDP‑Ec‑AE increased the tumor growth inhibition rate by 20% compared with natural LDM. The results indicated that the introduction of ABD‑based multi‑functional drug delivery may be an effective approach to improve the efficacy of antitumor drugs, especially for K‑ras mutant cancers.

Recent trends in protein and peptide-based biomaterials for advanced drug delivery

Engineering protein and peptide-based materials for drug delivery applications has gained momentum due to their biochemical and biophysical properties over synthetic materials, including biocompatibility, ease of synthesis and purification, tunability, scalability, and lack of toxicity. These biomolecules have been used to develop a host of drug delivery platforms, such as peptide- and protein-drug conjugates, injectable particles, and drug depots to deliver small molecule drugs, therapeutic proteins, and nucleic acids. In this review, we discuss progress in engineering the architecture and biological functions of peptide-based biomaterials -naturally derived, chemically synthesized and recombinant- with a focus on the molecular features that modulate their structure-function relationships for drug delivery.

Imidazole carbamate probes for affinity guided azide-transfer to metal-binding proteins

Probes for affinity guided conjugation have shown great promise for the preparation of high-quality protein conjugates.