A recombinantly tailored β-defensin that displays intensive macropinocytosis-mediated uptake exerting potent efficacy against K-Ras mutant pancreatic cancer

Enhanced intracellular uptake of an albumin fusion protein in cancer cells by its forced cell surface recruitment

Albumin fusion or conjugation is a well-established technique for tumor delivery and is mainly mediated by albumin-induced caveolae-dependent endocytosis. We report that caveolae-dependent endocytic signaling activated by human serum albumin (HSA) is not sufficiently strong to induce cellular uptake, mainly due to its electrostatic repulsion from the negatively charged cell surface sulfated glycosaminoglycans (GAGs), and fusion of the cell-surface-retained protein with HSA is an effective strategy to activate the HSA-induced endocytic signal, thereby improving its intracellular uptake. In this study, human lactoferrin (hLF), a protein that accumulates on the cell surface along with GAGs, was selected for delivery into human lung adenocarcinoma PC-14 cells. When added exogenously, hLF-fused HSA (hLF-HSA) was successfully endocytosed, whereas the simultaneous addition of HSA and hLF did not result in endocytosis, indicating less efficient activation of endocytic signaling by HSA alone and the importance of its fusion. Importantly, the treatment of cells with chlorate, a known inhibitor of GAG sulfation, dramatically suppressed the endocytosis of hLF-HSA owing to the loss of the hLF-GAG interaction. Therefore, the cell-surface localization of HSA imposed by fusion with the cell-surface-retained protein enhances its binding to the relevant receptor, which improves intracellular delivery as an albumin-fusion platform.

Recent advancements in fusion protein technologies in oncotherapy: A review

Cancer is a complicated, adaptable, and heterogeneous disease caused by a wide variety of genetic changes that might impair ability of cells to function normally. The majority of the tumors can only be shrunk using conventional oncology therapies like chemotherapy, radiation, and surgical resection, and the tumor often recurs. The inability of conventional cancer therapies to completely destroy the Cancer Stem Cells (CSCs) that otherwise lead to therapy resistance is thus addressed by therapeutic approaches that concentrate on targeting CSCs and their micro-environmental niche. In this review, we summarize approaches that are used for the development of fusion proteins and their therapeutic applications for treating cancer. The main purpose of making advancements towards the fusion technology instead of using conventional treatment methods is to achieve a prolonged half-life of the therapeutic drugs. The fusion of drugs to the immune response enhancing cytokines or the fusion of antibody and cytokines not only increases half-life but also increase the stability of the anti-tumor drug. Several molecules including different fragments of antibodies, cytokines, Human Serum Albumin, transferrin, XTEN polymers, Elastin-like polypeptides (ELPs) can be employed as a fusion partner and the resulting fusion proteins are reported to show enhanced anti-tumor response.

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.

Bioactive Peptides: Potential Impact on the Treatment of Gastrointestinal Cancers

We have reviewed the potential use of bioactive peptides in the treatment of gastrointestinal (GI) malignancies, which are a significant cause of morbidity and mortality globally. Conventional therapies, such as surgery, chemotherapy, and radiotherapy, are associated with numerous side effects that may lead to longterm complications. Bioactive peptides are short-chain amino acids that can be extracted from natural sources or synthesized, and they have various potential health benefits, including anti-inflammatory, anti-hypertensive, antioxidant, antimicrobial, and anti-cancer properties. Bioactive peptides can be acquired from animal or plant sources, and can be classified based on their function, such as ACE-inhibiting, antimicrobial, and electrolyte- regulating peptides. Recent studies have demonstrated the promising role of bioactive peptides in tumor suppression, especially when combined with conventional therapies. In this study, we have reviewed the beneficial properties of bioactive peptides and their role in suppressing tumor activity. The mechanisms of bioactive peptides in tumor suppression are discussed. We have further reviewed the findings of preclinical and clinical studies that have investigated the application of bioactive peptides in the treatment of GI cancers. This review highlights the potential use of bioactive peptides as a promising treatment method for GI malignancies to increase the quality of life of GI cancer patients.

The recombinant defensin/HSA fusion protein that inhibits NF-κb associated with intensive macropinocytosis shows potent efficacy against pancreatic cancer

KRAS mutation and NF-κB both play crucial role in pancreatic cancer; in addition, defensin, the peptide mediator in innate immunity, can inhibit NF-κB. Assuming a strategy that targets both NF-κB and concomitantly the mutated KRAS indirectly via intensive macropinocytosis, we designed and generated a recombinant protein DF2-HSA which consists of two molecules of human beta-defensin 2 (HBD2) and a moiety of human serum albumin (HSA). As shown, the recombinant protein DF2-HSA markedly down-regulated NF-κB in both KRAS mutant MIA PaCa-2 cells and wild type BxPC-3 cells. Determined by confocal microscopy, the uptake of DF2-HSA in MIA PaCa-2 cells was more intense than that in BxPC-3 cells. The uptake was blocked by the specific inhibitor EIPA, indicating that DF2-HSA internalized via macropinocytosis. DF2-HSA displayed more potent cytotoxicity to cancer cells than HBD2. DF2-HSA induced apoptosis in cancer cells. Notably, DF2-HSA inhibited tumor cell spheroid formation, an effect comparable to that of salinomycin. DF2-HSA inhibited tumor cell migration and invasion. As detected with scanning electron microscopy, DF2-HSA strongly depleted filopodia on cell surface; and salinomycin induced similar changes. By in vivo imaging, DF2-HSA displayed intense tumor-site accumulation and lasting retention for over 14 days; however, HBD2 showed much less tumor-site accumulation and a shorter retention time for only 24 h. DF2-HSA suppressed the growth of pancreatic cancer MIA PaCa-2 xenograft in athymic mice; and its combination with gemcitabine achieved higher antitumor efficacy. In summary, the recombinant defensin/HSA fusion protein that inhibits NF-κb associated with intensive macropinocytosis is highly effective against pancreatic cancer.

Exploiting macropinocytosis for drug delivery into KRAS mutant cancer

KRAS mutations are one of the most common gene mutations linked to cancer, presenting in approximately 25% of all tumors, especially pancreatic, lung, and colorectal cancers. Mutant KRAS has long been considered an undruggable target, stalling progress in direct KRAS targeting for many years, while targeted drug delivery into KRAS mutant cells utilizing their transformed metabolic behavior might present an alternative opportunity. Macropinocytosis, a nonselective, fluid-phase, endocytic route, was found to be upregulated as a metabolic feature in KRAS-driven tumors and plays a critical role in nutrient acquisition from extracellular fluids. With the observation that a variety of drug delivery systems could be internalized by KRAS mutant cancer cells through macropinocytosis, exploiting macropinocytosis for intracellular delivery of therapeutics into KRAS mutant tumor cells is emerging as a new drug delivery expedition. In this article, we summarized cancer biology studies that examined KRAS mutation-induced macropinocytosis, reviewed recent studies exploiting macropinocytosis enhancement for KRAS mutant cancer cell-selective drug delivery, and discussed the potential opportunities, challenges and pitfalls of this strategy.

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.

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.

Engineered Human Monoclonal scFv to Receptor Binding Domain of Ebolavirus

(1) Background: Ebolavirus (EBOV) poses as a significant threat for human health by frequently causing epidemics of the highly contagious Ebola virus disease (EVD). EBOV glycoprotein (GP), as a sole surface glycoprotein, needs to be cleaved in endosomes to fully expose a receptor-binding domain (RBD) containing a receptor-binding site (RBS) for receptor binding and genome entry into cytoplasm for replication. RBDs are highly conserved among EBOV species, so they are an attractive target for broadly effective anti-EBOV drug development. (2) Methods: Phage display technology was used as a tool to isolate human single-chain antibodies (HuscFv) that bind to recombinant RBDs from a human scFv (HuscFv) phage display library. The RBD-bound HuscFvs were fused with cell-penetrating peptide (CPP), and cell-penetrating antibodies (transbodies) were made, produced from the phage-infected E. coli clones and characterized. (3) Results: Among the HuscFvs obtained from phage-infected E. coli clones, HuscFvs of three clones, HuscFv4, HuscFv11, and HuscFv14, the non-cell-penetrable or cell-penetrable HuscFv4 effectively neutralized cellular entry of EBOV-like particles (VLPs). While all HuscFvs were found to bind cleaved GP (GPcl), their presumptive binding sites were markedly different, as determined by molecular docking. (4) Conclusions: The HuscFv4 could be a promising therapeutic agent against EBOV infection.

Next generation sequencing and functional pathway analysis to understand the mechanism of action of copper-tolfenamic acid against pancreatic cancer cells

Anti-cancer activity of tolfenamic acid (TA) in preclinical models for pancreatic cancer (PaCa) is well established. Since the dosage for anti-cancer actions of TA is rather high, we recently demonstrated that IC₅₀ values of Copper-TA are 30-80% less than TA in 12 cancer cell lines. This study elucidates the underlying mechanisms of Copper-TA in PaCa cells. Control and Copper-TA (IC₅₀) treated PaCa cells were processed by next-generation sequencing (NGS) to determine differentially expressed genes using HTG EdgeSeq Oncology Biomarker panel. Ingenuity Pathway Analysis (IPA®) was used to identify functional significance of altered genes. The conformational studies for assessing the expression of key regulators and genes were conducted by Western blot and qPCR. IPA® identified several networks, regulators, as well as molecular and cellular functions associated with cancer. The top 5 molecular and cellular functions affected by Cu-TA treatment were cell death and survival, cellular development, cell growth and proliferation, cell cycle and cellular movement. The expression of top upstream regulators was confirmed by Western blot analysis while qPCR results of selected genes demonstrated that Copper-TA is efficacious at lower doses than TA. Results suggest that Copper-TA alters genes/key regulators associated with cancer and potentially serve as an effective anti-cancer agent.

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.

CDK11p110 plays a critical role in the tumorigenicity of esophageal squamous cell carcinoma cells and is a potential drug target

Esophageal squamous cell carcinoma (ESCC) is a serious malignancy with limited options for targeted therapy. The exploration of novel targeted therapies for combating ESCC is urgently needed. Cyclin-dependent kinases (CDKs) play important roles in the progression of cancers; however, the function of CDK11^p110 (cyclin-dependent kinase 11^p110) in ESCC is still unknown. Here, we investigated the effects and molecular mechanisms of CDK11^p110 in the proliferation and growth of ESCC by examining the expression of CDK11^p110 in ESCC tissues and by detecting phenotypic changes in ESCC cells after CDK11^p110 knockdown or overexpression in vitro and in vivo. According to the tissue microarray analysis, compared with its expression level in normal tissues, the expression level of CDK11^p110 was significantly elevated in ESCC tissues; this result was in concordance with the data in TCGA (The Cancer Genome Atlas) datasets. In addition, RNAi-mediated CDK11^p110 silencing exerted a substantial inhibitory effect on the proliferation, clonogenicity and migration ability of ESCC cells. Further study indicated that CDK11^p110 knockdown arrested ESCC cells in the G2/M phase of the cell cycle and induced cell apoptosis. Moreover, stable shRNA-mediated CDK11^p110 knockdown inhibited tumor growth in an ESCC xenograft model, and overexpression of CDK11^p110 enhanced tumor growth. In addition, the Ki67 proliferation index was closely associated with the elevation or depletion of CDK11^p110 in vivo. In summary, this study provides evidence that CDK11^p110 play a critical role in the tumorigenicity of ESCC cells, which suggests that CDK11^p110 may be a promising therapeutic target in ESCC. Abbreviations: CDKs: cyclin-dependent kinases; CDK11: Cyclin-dependent kinase 11; CDK11^p110: Cyclin-dependent kinase 11^p110, the larger isomer of cyclin-dependent kinase 11; ESCC: esophageal squamous cell carcinoma; FACS: fluorescence-activated cell sorting; FDA: the Food and Drug Administration; TCGA: The Cancer Genome Atlas; TMA: tissue microarray.

Enediyne-activated, EGFR-targeted human β-defensin 1 has therapeutic efficacy against non-small cell lung carcinoma

Human β-defensins contain an oncolytic motif that binds to tumor cell membranes and mediate permeabilization, rapid induction of cytolysis, and apoptosis. Previous studies have indicated that a fragment of the mature human β-defensin-1 (HBD1) peptide (DF) has antitumor properties. While targeted drug treatments using fusion proteins have been shown to increase drug efficacy, this phenomenon has not been studied for this defensin. Thus, in this study, we designed and prepared a fusion protein containing this HBD1 fragment and an epidermal growth factor receptor (EGFR)-targeting oligopeptide (Ec) as well as lidamycin (LDM), an extremely potent cytotoxic antitumor antibiotic, which consists of an apoprotein (LDP) and a highly active enediyne (AE). The fusion protein (Ec-LDP-DF) and its enediyne-integrated fusion protein (Ec-LDP(AE)-DF) were then purified and used to treat lung carcinoma cells in culture as well as lung carcinoma xenograft mouse models. The multifunctional fusion protein Ec-LDP-DF was shown to effectively bind to EGFR-expressing tumor cells. Furthermore, the enediyne-energized Ec-LDP(AE)-DF analog exhibited extremely potent cytotoxicity in NSCLC cell lines and an IC₅₀ less than 10^-10 mol/L. Ec-LDP(AE)-DF also significantly inhibited the growth of human carcinoma A549 and H460 xenografts in athymic mice at well-tolerated doses. Treatment resulted in cell cycle arrest and apoptosis in a dose-dependent manner. EGF-stimulated EGFR phosphorylation was also abolished by Ec-LDP(AE)-DF. In summary, our understanding of the role of defensins in cancer development and progression is continually expanding, and Ec-LDP(AE)-DF is a promising cancer cell-targeting agent for NSCLC.

EGFR-targeting, β-defensin-tailored fusion protein exhibits high therapeutic efficacy against EGFR-expressed human carcinoma via mitochondria-mediated apoptosis

Defensins play an essential role in innate immunity. In this study, a novel recombinant β-defensin that targets the epidermal growth factor receptor (EGFR) was designed and prepared. The EGFR-targeting β-defensin consists of an EGF-derived oligopeptide (Ec), a β-defensin-1 peptide (hBD1) and a lidamycin-derived apoprotein (LDP), which serves as the "scaffold" for the fusion protein (Ec-LDP-hBD1). Ec-LDP-hBD1 effectively bound to EGFR highly expressed human epidermoid carcinoma A431 cells. The cytotoxicity of Ec-LDP-hBD1 to EGFR highly expressed A431 cells was more potent than that to EGFR low-expressed human lung carcinoma A549 and H460 cells (the IC₅₀ values in A431, A549, and H460 cells were 1.8 ± 0.55, 11.9 ± 0.51, and 5.19 ± 1.21 μmol/L, respectively); in addition, the cytotoxicity of Ec-LDP-hBD1 was much stronger than that of Ec-LDP and hBD1. Moreover, Ec-LDP-hBD1 suppressed cancer cell proliferation and induced mitochondria-mediated apoptosis. Its in vivo anticancer action was evaluated in athymic mice with A431 and H460 xenografts. The mice were administered Ec-LDP-hBD1 (5, 10 mg/kg, i.v.) two times with a weekly interval. Administration of Ec-LDP-hBD1 markedly inhibited the tumor growth without significant body weight changes. The in vivo imaging further revealed that Ec-LDP-hBD1 had a tumor-specific distribution with a clear image of localization. The results demonstrate that the novel recombinant EGFR-targeting β-defensin Ec-LDP-hBD1 displays both selectivity and enhanced cytotoxicity against relevant cancer cells by inducing mitochondria-mediated apoptosis and exhibits high therapeutic efficacy against the EGFR-expressed carcinoma xenograft. This novel format of β-defensin, which induces mitochondrial-mediated apoptosis, may play an active role in EGFR-targeting cancer therapy.

GRP75 modulates oncogenic Dbl-driven endocytosis derailed via the CHIP-mediated ubiquitin degradation pathway

Chaperone-assisted proteasome degradation of oncogenic protein acts as an upstream signal controlling tumorigenesis and progression. The understanding of the co-regulation of chaperone and oncoprotein of endocytosis pathways is extremely limited. In this study, we showed for the first time that proto-Dbl (dbl proto-oncogene product) is co-enriched with mitochondrial chaperone GRP75 in endocytosis vesicles from ovarian cancer cells. onco-Dbl, produced by oncogenic mutation/degradation of proto-Dbl, markedly enhanced cellular macropinocytosis but suppressed clathrin-mediated endocytosis and clathrin-independent endocytosis pathways, presenting a derailed endocytosis phenotype. GRP75 was associated with proto-Dbl inside cells and modulated Dbl-driven endocytosis derailed by a co-regulatory mode. In spite of not being a component of the Hsc70/Hsp90/proto-Dbl complex, the degradation of proto-Dbl was promoted by GRP75 through the CHIP-mediated ubiquitin–proteasome pathway, of which GRP75 acts as a cooperator with CHIP but also acts as a competitor to Hsc70 and Hsp90 in the multiple chaperones-assisted pro-folding/pro-degradation machinery. Knockdown or inhibition of GRP75 attenuated proto-Dbl degradation and reduced the onco-Dbl level, which differentially impaired Rho GTPases activation and therefore shifted the endocytosis-derailed phenotype. Our data uncovered a novel GRP75-Dbl endocytosis regulatory axis and provided an alternative using chaperone inhibitor to shut down the oncoprotein-driven endocytosis derailment mechanism.

A Macropinocytosis-Intensifying Albumin Domain-Based scFv Antibody and Its Conjugate Directed against K-Ras Mutant Pancreatic Cancer

Enhanced macropinocytosis has been found in K-Ras mutant pancreatic cancer cells, through which albumin can massively enter into the K-Ras-driven cancer cells, suggesting its role in serving as a macropinocytosis-intensifying drug delivery carrier. In the present study, a novel recombinant protein Fv-LDP-D3 and its reconstituted analogue Fv-LDP-D3-AE were designed and prepared. Fv is the fragment of an anti-EGFR antibody, D3 is the domain III of human serum albumin (HSA), LDP is the apoprotein of the antitumor antibiotic lidamycin (LDM), and AE is an extremely cytotoxic enediyne chromophore derived from LDM. As shown, the recombinant protein Fv-LDP-D3 presented intensive and selective binding capacity to pancreatic cancer cells and inhibited cell proliferation by blocking EGFR signaling. Moreover, Fv-LDP-D3 showed prominent tumor imaging in pancreatic carcinoma xenograft. The reconstituted, enediyne-integrated analogue Fv-LDP-D3-AE displayed highly potent cytotoxicity to pancreatic cancer cells through apoptosis induction and G2/M arrest. Fv-LDP-D3 and Fv-LDP-D3-AE markedly inhibited the tumor growth of the pancreatic carcinoma AsPC-1 xenograft. Study results indicated that the novel recombinant protein displays both EGFR-targeting and macropinocytosis-intensifying attributes, presenting a new format of scFv antibody that integrates with albumin domain III. It might be a feasible strategy to develop targeted drugs for K-Ras mutant pancreatic cancer.

Antimicrobial Peptides As Biologic and Immunotherapeutic Agents against Cancer: A Comprehensive Overview

Antimicrobial peptides (AMPs) are a pervasive and evolutionarily ancient component of innate host defense which is present in virtually all classes of life. In recent years, evidence has accumulated that parallel or de novo mechanisms by which AMPs curb infectious pathologies are also effective at restraining cancer cell proliferation and dissemination, and have consequently stimulated significant interest in their deployment as novel biologic and immunotherapeutic agents against human malignancies. In this review, we explicate the biochemical underpinnings of their tumor-selectivity, and discuss results of recent clinical trials (outside of oncologic indications) which substantiate their safety and tolerability profiles. Next, we present evidence for their preclinical antitumor activity, systematically organized by the major and minor classes of natural AMPs. Finally, we discuss the barriers to their clinical implementation and envision directions for further development.

Superoxide Dismutases in Pancreatic Cancer

The incidence of pancreatic cancer is increasing as the population ages but treatment advancements continue to lag far behind. The majority of pancreatic cancer patients have a K-ras oncogene mutation causing a shift in the redox state of the cell, favoring malignant proliferation. This mutation is believed to lead to nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation and superoxide overproduction, generating tumorigenic behavior. Superoxide dismutases (SODs) have been studied for their ability to manage the oxidative state of the cell by dismuting superoxide and inhibiting signals for pancreatic cancer growth. In particular, manganese superoxide dismutase has clearly shown importance in cell cycle regulation and has been found to be abnormally low in pancreatic cancer cells as well as the surrounding stromal tissue. Likewise, extracellular superoxide dismutase expression seems to favor suppression of pancreatic cancer growth. With an increased understanding of the redox behavior of pancreatic cancer and key regulators, new treatments are being developed with specific targets in mind. This review summarizes what is known about superoxide dismutases in pancreatic cancer and the most current treatment strategies to be advanced from this knowledge.

A new HDAC inhibitor cinnamoylphenazine shows antitumor activity in association with intensive macropinocytosis

Previous studies have shown that intensive macropinocytosis occurs in cancer cells and neutral red (NR) is noted for its capability to enter into the cell massively through a process mimetic to macropinocytosis. In addition, trans-cinnamic acid (tCA) has been found to be an inhibitor of histone deacetylase (HDAC). In the present study, cinnamoylphenazine (CA-PZ) that consists of NR and tCA moieties was synthesized and evaluated. As shown, CA-PZ massively entered into colon carcinoma HT-29 cells and pancreatic carcinoma MIA PaCa-2 cells and this entry was blocked by 5-(N-ethyl-N-isopropyl) amiloride (EIPA, an inhibitor of macropinocytosis), indicating a macropinocytosis-mediated uptake. Furthermore, CA-PZ markedly increased the protein expression levels of acetyl-H3, acetyl-H4 and p21 in HT-29 cells and MIA PaCa-2 cells. CA-PZ significantly inhibited the growth of colon carcinoma HT-29 and pancreatic carcinoma MIA PaCa-2 xenografts. By in vivo imaging, CA-PZ displayed prominent accumulation in the tumor xenografts. The study indicates that the newly synthesized CA-PZ acts as an HDAC inhibitor in association with intensive macropinocytosis-mediated intracellular delivery in cancer cells. The use of neutral red for preparation of chimeric molecules with the attribute of macropinocytosis-mediated intracellular delivery might open an alternative way for development of HDAC inhibitors.