Expression, purification, and breast cancer cell inhibiting effect of recombinant human lactoferrin C-lobe

Proteins and their functionalization for finding therapeutic avenues in cancer: Current status and future prospective

Despite the remarkable advancement in the health care sector, cancer remains the second most fatal disease globally. The existing conventional cancer treatments primarily include chemotherapy, which has been associated with little to severe side effects, and radiotherapy, which is usually expensive. To overcome these problems, target-specific nanocarriers have been explored for delivering chemo drugs. However, recent reports on using a few proteins having anticancer activity and further use of them as drug carriers have generated tremendous attention for furthering the research towards cancer therapy. Biomolecules, especially proteins, have emerged as suitable alternatives in cancer treatment due to multiple favourable properties including biocompatibility, biodegradability, and structural flexibility for easy surface functionalization. Several in vitro and in vivo studies have reported that various proteins derived from animal, plant, and bacterial species, demonstrated strong cytotoxic and antiproliferative properties against malignant cells in native and their different structural conformations. Moreover, surface tunable properties of these proteins help to bind a range of anticancer drugs and target ligands, thus making them efficient delivery agents in cancer therapy. Here, we discuss various proteins obtained from common exogenous sources and how they transform into effective anticancer agents. We also comprehensively discuss the tumor-killing mechanisms of different dietary proteins such as bovine α-lactalbumin, hen egg-white lysozyme, and their conjugates. We also articulate how protein nanostructures can be used as carriers for delivering cancer drugs and theranostics, and strategies to be adopted for improving their in vivo delivery and targeting. We further discuss the FDA-approved protein-based anticancer formulations along with those in different phases of clinical trials.

Antimicrobial peptides as potential therapeutics for breast cancer

Breast cancer is the most common and deadliest cancer in women worldwide. Although notable advances have been achieved in the treatment of breast cancer, the overall survival rate of metastatic breast cancer patients is still considerably low due to the development of resistance to breast cancer chemotherapeutic agents and the non-optimal specificity of the current generation of cancer medications. Hence, there is a growing interest in the search for alternative therapeutics with novel anticancer mechanisms. Recently, antimicrobial peptides (AMPs) have gained much attention due to their cost-effectiveness, high specificity of action, and robust efficacy. However, there are no clinical data available about their efficacy. This warrants the increasing need for clinical trials to be conducted to assess the efficacy of this new class of drugs. Here, we will focus on the recent progress in the use of AMPs for breast cancer therapy and will highlight their modes of action. Finally, we will discuss the combination of AMP-based therapeutics with other breast cancer therapy strategies, including nanotherapy and chemotherapy, which may provide a potential avenue for overcoming drug resistance.

Lactoferrin: A Glycoprotein Involved in Immunomodulation, Anticancer, and Antimicrobial Processes

Lactoferrin is an iron binding glycoprotein with multiple roles in the body. Its participation in apoptotic processes in cancer cells, its ability to modulate various reactions of the immune system, and its activity against a broad spectrum of pathogenic microorganisms, including respiratory viruses, have made it a protein of broad interest in pharmaceutical and food research and industry. In this review, we have focused on describing the most important functions of lactoferrin and the possible mechanisms of action that lead to its function.

Lactoferrin-containing immunocomplex mediates antitumor effects by resetting tumor-associated macrophages to M1 phenotype

Background

Tumor-associated macrophages (TAMs) resemble M2-polarized cells with potent immunosuppressive activity and play a pivotal role in tumor growth and progression. Converting TAMs to proinflammatory M1-like phenotype is thus an attractive strategy for antitumor immunotherapy.

Methods

A mouse IgG₁ (kappa) monoclonal Ab, M-860, specific to human lactoferrin (LTF) was generated by using the traditional hybridoma cell fusion technology. TAMs were generated by culturing human and mouse CD14⁺ monocytes in tumor-conditioned media containing a cytokine cocktail containing recombinant interleukin-4 (IL-4), interleukin-10 (IL-10) and macrophage colony stimulating factor (M-CSF). TAMs after treatment with immunocomplex (IC) between human LTF and M860 (LTF-IC) were phenotypically and functionally characterized by flow cytometry (FACS), ELISA, Q-PCR and killing assays. The antitumor effects of LTF-IC were further analyzed using in vivo experiments employing tumor-bearing human FcγRIIa-transgenic mouse models.

Results

Through coligation of membrane-bound CD14 and FcγRIIa, LTF-IC rendered TAMs not only M2 to M1 conversion, evidenced by increased tumor necrosis factor α production, down-regulated M2-specific markers (CD206, arginase-1 and vascular endothelial growth factor) and upregulated M1-specific markers (CD86 and HLA-DR) expression, but also potent tumoricidal activity in vitro. LTF-IC administration conferred antitumor protective efficacy and prolonged animal survival in FcγRIIa-transgenic mice, accompanied by accumulation of M1-like macrophages as well as significantly reduced infiltration of immunosuppressive myeloid-derived suppressor cells and regulatory T cells in solid tumor tissues.

Conclusions

LTF-IC is a promising cancer therapeutic agent capable of converting TAMs into tumoricidal M1-like cells.

Identification of blood protein biomarkers for breast cancer staging by integrative transcriptome and proteome analyses

Breast cancer is the most common malignancy for women. Accurate prediction of breast cancer and its pathological stages is important for treatment decision-making. Although many studies have focused on discovering circulating biomarkers of breast cancer, no such biomarkers have been reported for different stages of this disease. In this study, we identified blood protein biomarkers for each stage of breast cancer by analyzing transcriptome and proteome data from patients. Analysis of the TCGA transcriptome datasets revealed that a large number of genes were differentially expressed in tumor samples of each stage of breast cancer compared with adjacent normal tissues. Blood-secretory proteins encoded by these genes were then predicted by bioinformatics programs. Furthermore, iTRAQ-based proteomic analysis was conducted for plasma samples of breast cancer patients with different stages. A portion of predicted blood-secretory proteins could be detected and verified differentially expressed. Finally, several proteins were chosen as potential blood protein biomarkers for different stages of breast cancer due to their consistent expression patterns at both mRNA and protein levels. Overall, our data provide new insights into diagnosis and classification of breast cancer as well as selection of optimal treatments. SIGNIFICANCE: We identified blood protein biomarkers for each stage of breast cancer by analyzing tissue-based transcriptome and blood-based proteome data from patients. To our knowledge, this is the first time to try to identify blood protein biomarkers for different stages of breast cancer via these integrative analyses. Our data may provide new insights into diagnosis and classification of breast cancer as well as selection of optimal treatment.

Albumin fusion at the N-terminus or C-terminus of human lactoferrin leads to improved pharmacokinetics and anti-proliferative effects on cancer cell lines

Human lactoferrin (hLF), a soluble factor of the innate immune system, exhibits various biological functions and therefore has potential as a therapeutic protein. However, the clinical applications of hLF are limited by its low stability in blood. We therefore attempted to resolve this by producing recombinant hLF fused to human serum albumin (HSA). Two HSA-fused hLFs with different fusion orientations (hLF-HSA and HSA-hLF) were produced in Chinese hamster ovary (CHO) DG44 cells. hLF-HSA revealed higher thermal stability, resistance to peptic degradation, and stability during the process of cellular uptake and release in an intestinal enterocyte model (Caco-2 cells) than HSA-hLF. The lower stability of HSA-hLF is presumably due to the steric hindrance imposed by HSA fusion to the N-terminus of hLF. Both HSA fusion proteins, especially HSA-hLF, displayed improved pharmacokinetic properties despite the lower protein stability of HSA-hLF. hLF-HSA and HSA-hLF exhibited approximately 3.3- and 20.7-fold longer half-lives (64.0 and 403.6 min), respectively, than holo-rhLF (19.5 min). Both HSA fusion proteins were found to exert enhanced growth inhibition effects on cancer cells in vitro, but not normal cells. Their enhanced growth inhibitory activities were considered to be due to the synergetic effects of hLF and HSA because hLF alone or HSA alone failed to exert such an effect. Altogether, Fusion of HSA to hLF yielded superior pharmacokinetics and anti-proliferative activities against cancer cells. HSA-fused hLF is a novel candidate for further application of hLF as biopharmaceuticals for intravenous administration.

Functional analysis of recombinant buffalo lactoferrin and monoferric lobes and their cytotoxic effect on buffalo mammary epithelial cells

Lactoferrin (Lf) has been involved in diverse type of cellular activities and its biochemical properties are species specific. Lf is a bilobal molecule in which each lobe binds with one Fe²⁺/Fe³⁺ ion. A lot of physiological effects of Lf are regulated by its iron binding and release properties; however these properties are species-specific. To understand the iron-binding, thermal stability and cytotoxic effect of buffalo Lf (buLf) and contribution of individual N- and C-terminal lobes therein, buLf and the truncated monoferric lobes were expressed in Kluyveromyces lactis or Pichia pastoris yeast expression systems. The iron-uptake/release behavior and thermal stability of recombinant buLf was observed similar to the Lf purified from buffalo milk. Supplementation of recombinant buLf to the buffalo mammary epithelial cells (BuMEC) culture decreased their proliferation and the cell viability in a dose dependent manner. The cell growth decreased by 37% at 1.0 mg/ml Lf. C-lobe decreased the viability of BuMEC by 15% at 1 mg/ml. The C-lobe showed greater cytotoxic effect against BuMEC in comparison to N-lobe. buLf caused a reduced expression of the casein in BuMEC. At 1.0 mg/ml of buLf, CSN2 transcript level was reduced by 74% and 78% in the normal and hormone free media, respectively. The expression of IL-1β gene in BuMEC increased by 4-5 fold in the presence of 1.0 mg/ml of Lf. The effect was similar to that observed in the involutory mammary gland, suggesting the role of elevated level of Lf in remodeling of buffalo mammary tissue during involution.