Abstract
The photodynamic treatment for antimicrobial applications or anticancer therapy relies on reactive oxygen species generated by photosensitizing molecules after absorption of visible or near-infrared light. If the photosensitizing molecule is in close vicinity of the microorganism or the malignant cell, a photocytotoxic action is exerted. Therefore, the effectiveness of photosensitizing compounds strongly depends on their capability to target microbial or cancer-specific proteins. In this study, we report on the preparation and preliminary characterization of human recombinant myoglobin fused to the vasoactive intestinal peptide to target vasoactive intestinal peptide receptor (VPAC) receptors. Fe-protoporphyrin IX was replaced by the photosensitizing compound Zn-protoporphyrin IX. Taking advantage of the fluorescence emission by Zn-protoporphyrin IX, we show that the construct can bind prostate cancer cells where the VPAC receptors are expressed.
Introduction
Photodynamic therapy (PDT) of cancer is an adjuvant therapeutic procedure that combines an otherwise harmless compound (the photosensitizer, PS) with visible light and molecular oxygen to achieve the photoinduced killing of malignant cells [1–5]. Cytotoxicity is obtained through the action of reactive oxygen species (ROS), mostly singlet oxygen, produced by the interaction between the excited states of the PS and molecular oxygen [6]. The short lifetime of ROS (the lifetime of singlet oxygen in water is about 3 µs [7] and that of O2 −˙ radical is ca. 1 μs [8]) means that the oxidant action of these species is exerted only against molecules located within some 200 nm from their generation site [9,10], which requires the photoactive compound to be brought in close vicinity of sensitive cellular components.
Precise and effective delivery of PS molecules to their biological targets is still an open issue in PDT. Their low water solubility, which reduces bioavailability, is normally addressed using suitable carrier systems [11–15]. Among possible carriers, proteins offer the advantage of being inherently biocompatible. Particularly, PSs can be covalently conjugated with peptides or proteins that target specific cells [12]. Antibodies are an obvious choice [12–18], although their recombinant production in mammalian cells is costly and time-consuming. Therefore, single-domain antibodies called nanobodies were proposed [16]. The use of short peptides to introduce targeting properties in supramolecular complexes between a PS and a carrier for PDT applications was also suggested. In one strategy, short peptides are grafted on nanoparticles [19,20] or supramolecular assemblies [21] functionalizing with PS molecules. Peptides were also conjugated directly to PS molecules [12,22,23].
As an alternative to covalent conjugation to amino acid residues, which might result in heterogeneous products, the delivery of hydrophobic PSs can take advantage of their spontaneous binding to internal hydrophobic protein pockets of proper size. Within the binding pocket, PSs preserve their monomeric, photoactive excited states, leading to fluorescence emission and generation of ROS [24–30].
Proteins capable of spontaneously binding PSs can be engineered to encompass a signaling peptide endowed with the desired target specificity [31,32]. Recombinant carriers that include both the PS-binding moiety and the targeting peptide do not require additional chemical modifications – which would need further purification steps – unlike chemically conjugated peptides [12]. Moreover, several peptides targeting drug receptors overexpressed in cancer cells have been characterized for both diagnostic purposes [33] and therapeutic applications [34] and their incorporation in the sequence of a recombinant protein is straightforward. The combination of PSs with these functionalized nanostructures consisting of PS-binding proteins fused with targeting peptides has the potential for intelligent drug delivery with theranostic capabilities [35].
Among protein-based photosensitizing compounds, zinc-substituted myoglobin (ZnMb) is of special interest. The photosensitizing properties of ZnMb were reported by Lepeshkevich et al. [36]. In their study, the iron ion at the center of the heme moiety of Mb was replaced with a Zn(ii) ion. Just like Fe-protoporphyrin IX, Zn-protoporphyrin IX is bound to the protein matrix using a coordinate bond to the proximal HisF9. This introduces a photoactive cofactor in the heme pocket that can photosensitize the production of 1O2 with yield Ф Δ = (0.9 ± 0.1) [36]. We have recently broken these properties to obtain a photosensitizing material that is effective against planktonic Staphylococcus aureus, taking advantage of weak interactions between the protein and the bacterial wall [37].
The superior photosensitizing properties of ZnMb could be made more effective if targeting properties are introduced into the protein carrier by fusing the myoglobin gene with that coding for a short peptide sequence that binds the molecular species of interest.
In this study, we explored this concept and reported on the preparation and preliminary characterization of human recombinant myoglobin genetically fused to the vasoactive intestinal peptide (VIP). VIP is a 28-amino acid peptide that belongs to the glucagon/secretin superfamily and is an agonist of the VPAC1 and VPAC2 G-protein-coupled receptors [38,39]. VIP basic peptide contains three lysines (no. 15, 20, and 21) and two arginines (no. 12 and 14) [40,41]. VPAC1 is overexpressed in several frequently occurring human tumors, including breast, prostate, pancreas, lung, colon, stomach, liver, and bladder carcinomas, as well as lymphomas and meningiomas [42,43]. In particular, VPAC1 was identified in prostate cancer cells, where overexpression was reported [42,44]. VPAC receptors were suggested to play a major role in the progression and angiogenesis of several malignancies [45]. Reverse transcriptase polymerase chain reaction studies, as well as functional studies using a specific agonist and antagonist for each receptor subtype, peptide binding, and adenylate cyclase stimulation, show that VPAC1 and VPAC2 receptors are present in prostate cancer cell line (PC3) cells [46,47], although more recent data suggest that the expression of VPAC1 might be rather low [48].
The overexpression of VPAC1 on several common neoplastic tissues is receiving attention both for tumor imaging and targeted treatment by coupling cytotoxic agents to VIP analogs [49], as functional studies demonstrated a VIP-binding affinity for VPAC1 of 0.6 nM [50]. VIP analogs have been exploited to develop contrast agents mostly based on radionuclide-labeled probes for molecular imaging [45]. Nanoparticles designed for VIP drug delivery have also been developed [51].
In this study, we showed that the recombinantly expressed fusion protein myoglobin-VIP (Mb-VIP) is endowed with targeting capability towards cells overexpressing VPAC1, and can be turned into a photosensitizing compound by replacing Fe-heme with Zn-heme (ZnMb-VIP). The photosensitizing properties and the fluorescence emission by ZnMb-VIP make the compound a potentially theranostic agent.
Materials and methods
Gene
The synthetic gene encoding human myoglobin (NCBI Reference Sequence: NP_001349775.1) was codon-optimized for expression in Escherichia coli. The gene was fused at the N-terminal with a hexahistidine tag followed by a tobacco etch virus (TEV) protease recognition site. At the C-terminus, the gene was in-frame with a sequence encoding a thrombin recognition site followed by encoding the VIP peptide (HSDAVFTDNYTRLRKQMAVKKYLNSILN) [52]. The thrombin site was added to remove the VIP peptide from the final product if needed. The synthetic gene (Geneart, Life Technologies) was subcloned in a pET28a plasmid (Novagen, Merck group), which harbored a kanamycin resistance gene between the NcoI and SalI restriction sites. The final construct – named pMbVIP – was verified through sequencing. The plasmid was finally transformed into BL21 cells, BL21 star cells, Rosetta cells, and BL21 cells harboring the Takara plasmids (Takara Bio Inc., Shiga, Japan) for an initial expression screening. BL21 cells harboring the Takara 4 plasmid, which encodes for chaperones groES, groEL, and tig, were subsequently used for expression.
Expression of MbVIP
Single colonies of BL21 cells, BL21 star cells, Rosetta cells, and BL21 cells harboring the Takara plasmids (Takara Bio Inc., Shiga, Japan) were transformed with pMbVIP and isolated from Luria-Bertani (L.B.) agar plates containing the appropriate antibiotics. They were then inoculated in 50 mL of L.B. culture medium containing the appropriate antibiotics. The following day, 10 mL of the cultures were inoculated in 1 L of L.B. or DM1 medium and grown at 37°C until an absorbance of 0.4 OD was achieved. At that point, 1 mM isopropyl ß-D-1-thiogalactopyranoside was added, and the culture was allowed to grow at different temperatures ranging from 20 to 42°C, in the presence and absence of iron chloride (FeCl2) or hemin. Cells were recovered by centrifugation, resuspended in phosphate-buffered saline (PBS) buffer, and lysed by sonication. The proteins were then purified with immobilized metal affinity chromatography using a TALON® Superflow™ resin (Cytiva) and finally brought in a solution containing 100 mm of NaH2PO4 at pH 7. The proteins were then concentrated to around 1 mg/mL. The integrity of the proteins obtained from the various cultures was tested by matrix-assisted laser desorption/ionization (MALDI) spectrometry (MALDI TOF/TOF 4800 Plus, AB SCIEX), quantified by sodium dodecyl-sulfate polyacrylamide gel electrophoresis, and characterized spectroscopically (Cary4000, Agilent). Since expression in BL21 cells transformed with the Takara 4 plasmid in the presence of hemin and at 20°C offered the best results, the subsequent growth was carried out under these conditions, in the presence of 30 µg/mL kanamycin and 20 μg/mL chloramphenicol in all media. Upon induction, 1 μL tetracycline was also added to the cultures.
Heme exchange of MbVIP
Fe-heme was exchanged using a published protocol [37]. Briefly, the protein at 1 mg/mL concentration was first partially denatured by lowering the pH of its solution to around 2.8. Butanone was then added to extract Fe-heme. Butanone was then removed by extensive dialysis against a buffer containing 100 mm of NaH2PO4 at pH 7. Aliquots of a Zn-protoporphyrin IX solution at 10 mm concentration were then slowly added to the protein solution until a small molar excess was reached. Excess Zn-heme was removed by diafiltration, and the protein solution was brought to 0.3 mg/mL concentration.
Preparation of ZnMb
As a non-targeted control, horse Mb was prepared as Zn-protoporphyrin IX complex (ZnMb) as described [37].
Cell cultures
PC3 human prostate adenocarcinoma cells were grown in Ham F12 nutrient mixture, supplemented with 5% FBS and 1% penicillin–streptomycin solution. PC3 cells were seeded on Nunc plates (ThermoFisher) at 60–80% confluence and were used after incubation at 37°C and 5% CO2 for 24–48 h.
Spinning disk microscopy
Fluorescence imaging was performed with a spinning disk confocal microscope comprising an inverted microscope body (TiE, Nikon Instruments, Yokohama, Japan), an incubation system (OKOLAB, Naples, Italy), four laser lines (405, 488, 561, 640 nm) and two spinning disks containing about 20,000 pinholes coupled to the same number of microlenses (CSU-X1, Yokogawa, Tokyo, Japan), necessary to focus the excitation laser light. The fluorescence light was collected by an oil immersion 100× 1.4NA objective (Nikon Instruments, Yokohama, Japan) and acquired by an electron multiplying charge coupled device (EMCCD) camera (Ixon3 897 Andor, Oxford Instruments, Oxford, UK), characterized by high sensitivity and temporal resolution.
Time-lapse analysis
The cells placed in the Nunc have been positioned inside a suitable housing installed on the spinning disk that keeps cells at the temperature of 37°C, RH 95%, and a flow of 0.6 L/min. Different areas of the Nuncs were selected to follow the behavior of the cells in different parts of the sample at the same time. The time-lapse was activated by acquiring one frame each 2 min for the first 14 min and 1 frame each 5 min up to 69 min. Excitation 561 nm, emission 592/22 nm, exposure time 100 ms. For all the images, excitation was 561 nm, emission 592/22 nm, exposure time 100 ms, the pixels area 512 × 512, and the pixel size was 0.23 mm. The first frame was acquired without PS, after which, once the acquisition of the frame was completed, PS was added and the accumulation over time and the consequent photodamage were followed.
Results and discussion
Protein expression and characterization
Preliminary attempts at expressing Mb-VIP were carried out in BL21 cells, BL21 star cells, Rosetta cells, and BL21 cells harboring the Takara plasmids, grown in either L.B. broth or DM1 medium. The growth temperature after induction varied between 20 and 42°C. The addition of either FeCl2 or hemin at different concentrations was also tested. All expression attempts but those in cells containing the Takara 4 plasmid resulted in poor yields and partial hydrolysis of the C-terminus, as assessed by MALDI mass spectrometry. Indeed, the protein – with an expected molecular weight (M.W.) of 23,807 – partially exhibited an M.W. around 800 Da (data not shown), similar to that obtained upon digestion with thrombin. Digestion of the fraction with low M.W. with thrombin did not decrease further the observed m/z, indicating that the observed proteolysis occurred at the C-terminus. The expression in cells harboring the Takara 4 plasmid in the presence of hemin and at 20°C led to the highest yield and minimal hydrolysis at the C-terminus (Figure 1a). Upon heme substitution with Zn-heme, the absorption spectrum of the protein shows an intense Soret band peaked at 428 nm, and two Q-bands centered at 554 and 595 nm (Figure 1b) [36]. The fluorescence emission spectrum is characterized by an intense narrow band centered at 597 nm and a lower intensity band around 650 nm [36,37].

Characterization of MbVIP. (a) MALDI mass spectrum of Mb-VIP purified from BL21 cells cotransformed with the Takara 4 plasmid and grown overnight at 20°C. (b) Absorption (green) and fluorescence emission (red) spectra for ZnMb-VIP (4 µM) in PBS buffer. T = 20°C.
Interaction of PS compounds with PC3 cells
To assess the possible nonspecific interactions between ZnMb and VPAC1 expressing PC3 cells, we first incubated PC3 cells with ZnMb and collected images with a fast confocal spinning disk microscope. Over time, fluorescence was observed from the bulk solvent but not from cell components, which remained dark even after 1 h incubation (Figure 2). This is consistent with the lack of high-affinity binding of the water soluble ZnMb with the plasma membrane, as recently demonstrated for the complex between hypericin and apomyoglobin [27]. In that case, through confocal fluorescence microscopy, we showed that when apomyoglobin (myoglobin without heme) is used to transport the PS hypericin to tumor cells, the PS payload is rapidly and efficiently transferred to the plasma membrane, for which hypericin has a higher affinity. On the other hand, the protein carrier showed no interaction with the plasma membrane and remained solubilized in the surrounding medium [27].

Fast confocal spinning disk fluorescence imaging of PC3 cells treated with ZnMb (1 µM) at 0 min (a and d), 19 min (b and e), and 59 min (c and f) of accumulation time. Time-lapse one frame each 2 min for the first 14 min and 1 frame each 5–59 min. Excitation 561 nm, emission 592/22 nm, exposure time 100 ms. For all the images, the pixel’s area is 512 × 512, and the pixel size is 0.23 µm. 0-time was collected before the PS is added to the solution. Scale bar 5 µm.
To assess the capability of ZnMb-VIP to target VPAC1 receptors, PC3 cells were incubated with ZnMb-VIP and time-lapse images were collected from time 0 (before the ZnMb-VIP was added) on, for about 1 h (Figure 3). When ZnMb-VIP was added to PC3 cultures, fluorescence appeared on the plasma membrane after only ca. 2–4 min (Figure 3d), indicating high-affinity binding. Given the high affinity of VIP for VPAC1, this receptor is the most likely candidate for binding. It is predicted that unspecific binding of ZnMb-VIP through VIP direct insertion in the plasma membrane is unlikely to occur, considering its amino acid composition, which, according to the hydropathy scale of Kyte and Doolittle [53], does not show a relevant propensity to bind membranes.

Fast confocal spinning disk fluorescence imaging of PC3 cells before (a and c) and 4 min (b and d) after treatment with ZnMb-VIP (1 µM). Transmitted light (a and b), confocal fluorescence (c and d). Excitation 561 nm, emission 592/22 nm, exposure time 100 ms. For all the images, the pixel’s area is 512 × 512, and the pixel size is 0.23 µm. 0-time is collected before the PS is added to the solution. Scale bar 20 µm.
For a long time, extensive damage to the cell structure was observed (data not shown), which will be the subject of future functional investigations of the present compound.
Conclusion
Human recombinant myoglobin fused with VIP allowed to obtain a supramolecular complex where the globin domain preserved the well-known capability to bind and transport the heme, and the VIP domain can bind to its VPAC1 receptor. The system has the advantage of binding the modified Zn-heme, a well-characterized PS endowed with the red fluorescence emission. In comparison to other formulations, where PS molecules are covalently bound post-translationally to the recombinant proteins at reactive side chains of amino acids (typically Lys, Cys, or Glu) to a different extent from each preparation, the fusion construct binds stoichiometrically in the heme pocket. As such, the construct is a well-defined, single chemical species. An additional advantage of this small size, water-soluble protein is that it is stable fold (the protein is stable also under acidic conditions, with a pK a of about 3.8) [54], which allows its use under harsh environmental conditions too. While the system is interesting in itself for targeting several tumors characterized by VPAC1 overexpression, we emphasized that the construct can be easily adapted to target other receptors by introducing a different targeting peptide in place of VIP. Future studies will assess the potential of the compound for PDT.
Acknowledgments
S.A. and C.V. acknowledge financial support from Azienda USL di Piacenza, Italy, and Fondazione di Piacenza e Vigevano. A.D. acknowledges financial support from PRIN2017, 20177XJCHX_003.
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Conflict of interest: Authors state no conflict of interest.
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Data availability statement: The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.
References
[1] Agostinis P, Berg K, Cengel KA, Foster TH, Girotti AW, Gollnick SO, et al. Photodynamic therapy of cancer: an update. CA: Cancer J Clinicians. 2011;61(4):250–81.10.3322/caac.20114Search in Google Scholar PubMed PubMed Central
[2] dos Santos AF, de Almeida DRQ, Terra LF, Baptista MS, Labriola L. Photodynamic therapy in cancer treatment – an update review. J Cancer Metastasis Treat. 2019;5:25.10.20517/2394-4722.2018.83Search in Google Scholar
[3] Rapozzi V, D’Este F, Xodo LE. Molecular pathways in cancer response to photodynamic therapy. J Porphyr Phthalocyanines. 2019;23(4–5):410–8.10.1142/9789811223556_0004Search in Google Scholar
[4] Yanovsky RL, Bartenstein DW, Rogers GS, Isakoff SJ, Chen ST. Photodynamic therapy for solid tumors: a review of the literature. Photodermatol Photoimmunol Photomed. 2019;35(5):295–303.10.1111/phpp.12489Search in Google Scholar PubMed
[5] Menghua X, Quanming Z, Zihan S, Xuan W, Mengchu L, Yan J, et al. A review of light sources and enhanced targeting for photodynamic therapy. Curr Medicinal Chem. 2021;28(31):6437–57.10.2174/0929867328666210121122106Search in Google Scholar PubMed
[6] Ogilby PR. Singlet oxygen: there is indeed something new under the sun. Chem Soc Rev. 2010;39(8):3181–209.10.1039/b926014pSearch in Google Scholar PubMed
[7] Wilkinson F, Helman WP, Ross AB. Rate constants for the decay and reactions of the lowest electronically excited singlet state of molecular oxygen in solution. An expanded and revised compilation. J Phys Chem Ref Data. 1995;24:663–1021.10.1063/1.555965Search in Google Scholar
[8] Schmitt F-J, Renger G, Friedrich T, Kreslavski VD, Zharmukhamedov SK, Los DA, et al. Reactive oxygen species: re-evaluation of generation, monitoring and role in stress-signaling in phototrophic organisms. Biochim Biophys Acta (BBA) – Bioenerg. 2014;1837(6):835–48.10.1016/j.bbabio.2014.02.005Search in Google Scholar PubMed
[9] da Silva EFF, Pedersen BW, Breitenbach T, Toftegaard R, Kuimova MK, Arnaut LG, et al. Irradiation- and sensitizer-dependent changes in the lifetime of intracellular singlet oxygen produced in a photosensitized process. J Phys Chem B. 2012;116(1):445–61.10.1021/jp206739ySearch in Google Scholar PubMed
[10] Delcanale P, Abbruzzetti S, Viappiani C. Photodynamic treatment of pathogens. La Riv del Nuovo Cimento. 2022. 10.1007/s40766-022-00031-4.Search in Google Scholar
[11] DeRosa MC, Crutchley RJ. Photosensitized singlet oxygen and its applications. Coord Chem Rev. 2002;233–234(Supplement C):351–71.10.1016/S0010-8545(02)00034-6Search in Google Scholar
[12] Giuntini F, Alonso CMA, Boyle RW. Synthetic approaches for the conjugation of porphyrins and related macrocycles to peptides and proteins. Photochem Photobiol Sci. 2011;10(5):759–91.10.1039/c0pp00366bSearch in Google Scholar PubMed
[13] Bullous AJ, Alonso CMA, Boyle RW. Photosensitiser–antibody conjugates for photodynamic therapy. Photochem Photobiol Sci. 2011;10(5):721–50.10.1039/c0pp00266fSearch in Google Scholar PubMed
[14] Giuntini F, Boyle R, Sibrian-Vazquez M, Vicente MGH. Porphyrin conjugates for cancer therapy. In: Handbook of porphyrin science. Vol. 27. Singapore: World Scientific Publishing Co Pte Ltd; 2013. p. 303–416.10.1142/9789814407755_0017Search in Google Scholar
[15] Planas O, Boix-Garriga E, Rodríguez-Amigo T, Bresolí-Obach JB, Flors R, Viappiani C, et al. Newest approaches to singlet oxygen photosensitisation in biological media. In: Albini A, Fasani E, editors. Photochemistry. Vol. 42. London: The Royal Society of Chemistry; 2014.10.1039/9781782624547-00233Search in Google Scholar
[16] Fernandes SRG, Fernandes R, Sarmento B, Pereira PMR, Tomé JPC. Photoimmunoconjugates: novel synthetic strategies to target and treat cancer by photodynamic therapy. Org Biomolecular Chem. 2019;17(10):2579–93.10.1039/C8OB02902DSearch in Google Scholar
[17] Sandland J, Boyle RW. Photosensitizer antibody–drug conjugates: past, present, and future. Bioconjugate Chem. 2019;30(4):975–93.10.1021/acs.bioconjchem.9b00055Search in Google Scholar PubMed
[18] Pereira PMR, Korsak B, Sarmento B, Schneider RJ, Fernandes R, Tomé JPC. Antibodies armed with photosensitizers: from chemical synthesis to photobiological applications. Org Biomolecular Chem. 2015;13(9):2518–29.10.1039/C4OB02334JSearch in Google Scholar PubMed
[19] Dhaini B, Kenzhebayeva B, Ben-Mihoub A, Gries M, Acherar S, Baros F, et al. Peptide-conjugated nanoparticles for targeted photodynamic therapy. Nanophotonics. 2021;10(12):3089–134.10.1515/nanoph-2021-0275Search in Google Scholar
[20] Han K, Ma Z, Han H. Functional peptide-based nanoparticles for photodynamic therapy. J Mat Chem B. 2018;6(1):25–38.10.1039/C7TB02804KSearch in Google Scholar
[21] Jin H, Lin X, Gao M, Cui L, Liu Y. Peptide-decorated supramolecules for subcellular targeted cancer therapy: recent advances. Front Chem. 2020;8:824.10.3389/fchem.2020.00824Search in Google Scholar PubMed PubMed Central
[22] Schneider R, Tirand L, Frochot C, Vanderesse R, Thomas N, Gravier J, et al. Recent improvements in the use of synthetic peptides for a selective photodynamic therapy. Anti-Cancer Agents Med Chem. 2006;6(5):469–88.10.2174/187152006778226503Search in Google Scholar PubMed
[23] Boss M, Bos D, Frielink C, Sandker G, Bronkhorst P, van Lith SAM, et al. Receptor-targeted photodynamic therapy of glucagon-like peptide 1 receptor–positive lesions. J Nucl Med. 2020;61(11):1588–93.10.2967/jnumed.119.238998Search in Google Scholar PubMed PubMed Central
[24] Hally C, Delcanale P, Nonell S, Viappiani C, Abbruzzetti S. Photosensitizing proteins for antibacterial photodynamic inactivation. Transl Biophotonics. 2020;2(1–2):e201900031.10.1002/tbio.201900031Search in Google Scholar
[25] Cozzolino M, Pesce L, Pezzuoli D, Montali C, Brancaleon L, Cavanna L, et al. Apomyoglobin is an efficient carrier for zinc phthalocyanine in photodynamic therapy of tumors. Biophys Chem. 2019;253:106228.10.1016/j.bpc.2019.106228Search in Google Scholar PubMed
[26] Cozzolino M, Delcanale P, Montali C, Tognolini M, Giorgio C, Corrado M, et al. Enhanced photosensitizing properties of protein bound curcumin. Life Sci. 2019;233:116710.10.1016/j.lfs.2019.116710Search in Google Scholar PubMed
[27] Bianchini P, Cozzolino M, Oneto M, Pesce L, Pennacchietti F, Tognolini M, et al. Hypericin – apomyoglobin an enhanced photosensitizer complex for the treatment of tumour cells. Biomacromolecules. 2019;20(5):2024–33.10.1021/acs.biomac.9b00222Search in Google Scholar PubMed
[28] Pezzuoli D, Cozzolino M, Montali C, Brancaleon L, Bianchini P, Zantedeschi M, et al. Serum albumins are efficient delivery systems for the photosensitizer hypericin in photosensitization-based treatments against Staphylococcus aureus. Food Control. 2018;94:254–62.10.1016/j.foodcont.2018.07.027Search in Google Scholar
[29] Rodríguez-Amigo B, Delcanale P, Rotger G, Juárez-Jiménez J, Abbruzzetti S, Summer A, et al. The complex of hypericin with β-lactoglobulin has antimicrobial activity with perspective applications in dairy industry. J Dairy Sci. 2015;98:89–94.10.3168/jds.2014-8691Search in Google Scholar PubMed
[30] Comas-Barceló J, Rodríguez-Amigo B, Abbruzzetti S, Rey-Puech Pd, Agut M, Nonell S, et al. A self-assembled nanostructured material with photosensitising properties. RSC Adv. 2013;3:17874–79.10.1039/c3ra42609bSearch in Google Scholar
[31] Sharman WM, van Lier JE, Allen CM. Targeted photodynamic therapy via receptor mediated delivery systems. Adv Drug Delivery Rev. 2004;56(1):53–76.10.1016/j.addr.2003.08.015Search in Google Scholar PubMed
[32] Hussain AF, Kampmeier F, von Felbert V, Merk H-F, Tur MK, Barth S. SNAP-tag technology mediates site specific conjugation of antibody fragments with a photosensitizer and improves target specific phototoxicity in tumor cells. Bioconjugate Chem. 2011;22(12):2487–95.10.1021/bc200304kSearch in Google Scholar PubMed
[33] Bai M, Bornhop DJ. Recent advances in receptor-targeted fluorescent probes for in vivo cancer imaging. Curr Medicinal Chem. 2012;19(28):4742–58.10.2174/092986712803341467Search in Google Scholar PubMed
[34] Shadidi M, Sioud M, Identification of novel carrier peptides for the specific delivery of therapeutics into cancer cells. FASEB J. 2003;17(2):256–8.10.1096/fj.02-0280fjeSearch in Google Scholar PubMed
[35] Lammers T, Aime S, Hennink WE, Storm G, Kiessling F. Theranostic Nanomedicine. Acc Chem Res. 2011;44(10):1029–38.10.1201/9780429399039-4Search in Google Scholar
[36] Lepeshkevich SV, Parkhats MV, Stasheuski AS, Britikov VV, Jarnikova ES, Usanov SA, et al. Photosensitized singlet oxygen luminescence from the protein matrix of Zn-substituted myoglobin. J Phys Chem A. 2014;118(10):1864–78.10.1021/jp501615hSearch in Google Scholar PubMed
[37] Delcanale P, Montali C, Rodriguez-Amigo B, Abbruzzetti S, Bruno S, Bianchini P, et al. Zinc-substituted myoglobin is a naturally occurring photo-antimicrobial agent with potential applications in food decontamination. J Agric Food Chem. 2016;64:8633–9.10.1021/acs.jafc.6b03368Search in Google Scholar PubMed
[38] Umetsu Y, Tenno T, Goda N, Shirakawa M, Ikegami T, Hiroaki H. Structural difference of vasoactive intestinal peptide in two distinct membrane-mimicking environments. Biochim Biophys Acta (BBA) – Proteins Proteom. 2011;1814(5):724–30.10.1016/j.bbapap.2011.03.009Search in Google Scholar PubMed
[39] Iwasaki M, Akiba Y, Kaunitz J. Recent advances in vasoactive intestinal peptide physiology and pathophysiology: focus on the gastrointestinal system [version 1; peer review: 4 approved]. F1000Research. 2019;8:1629.10.12688/f1000research.18039.1Search in Google Scholar PubMed PubMed Central
[40] Chakder S, Rattan S. The entire vasoactive intestinal polypeptide molecule is required for the activation of the vasoactive intestinal polypeptide receptor: functional and binding studies on opossum internal anal sphincter smooth muscle. J Pharmacol Exp Ther. 1993;266(1):392–9.Search in Google Scholar
[41] Trabulsi EJ, Tripathi SK, Gomella L, Solomides C, Wickstrom E, Thakur ML. Development of a voided urine assay for detecting prostate cancer non-invasively: a pilot study. BJU Int. 2017;119(6):885–95.10.1111/bju.13775Search in Google Scholar PubMed PubMed Central
[42] Reubi JC. In vitro evaluation of VIP/PACAP receptors in healthy and diseased human tissues: clinical implications. Ann N Y Acad Sci. 2000;921(1):1–25.10.1111/j.1749-6632.2000.tb06946.xSearch in Google Scholar PubMed
[43] Harmar AJ, Fahrenkrug J, Gozes I, Laburthe M, May V, Pisegna JR, et al. Pharmacology and functions of receptors for vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide: IUPHAR Review 1. Br J Pharmacol. 2012;166(1):4–17.10.1111/j.1476-5381.2012.01871.xSearch in Google Scholar PubMed PubMed Central
[44] Collado B, Carmena MJ, Sánchez-Chapado M, Ruíz-Villaespesa A, Bajo AM, Fernández-Martínez AB, et al. Expression of vasoactive intestinal peptide and functional VIP receptors in human prostate cancer: Antagonistic action of a growth-hormone-releasing hormone analog. Int J Oncol. 2005;26(6):1629–35.10.3892/ijo.26.6.1629Search in Google Scholar PubMed
[45] Tang B, Yong X, Xie R, Li Q, Yang S. Vasoactive intestinal peptide receptor-based imaging and treatment of tumors (review). Int J Oncol. 2014;44:1023–31.10.3892/ijo.2014.2276Search in Google Scholar PubMed
[46] Gutiérrez-Cañas I, Rodríguez-Henche N, Bolaños O, Carmena MJ, Prieto JC, Juarranz MG. VIP and PACAP are autocrine factors that protect the androgen-independent prostate cancer cell line PC-3 from apoptosis induced by serum withdrawal. Br J Pharmacol. 2003;139(5):1050–8.10.1038/sj.bjp.0705317Search in Google Scholar PubMed PubMed Central
[47] Fernández-Martínez AB, Bajo AM, Valdehita A, Isabel Arenas M, Sánchez-Chapado M, Carmena MJ, et al. Multifunctional role of VIP in prostate cancer progression in a xenograft model: Suppression by curcumin and COX-2 inhibitor NS-398. Peptides. 2009;30(12):2357–64.10.1016/j.peptides.2009.09.018Search in Google Scholar PubMed
[48] Lindner S, Fiedler L, Wängler B, Bartenstein P, Schirrmacher R, Wängler C. Design, synthesis and in vitro evaluation of heterobivalent peptidic radioligands targeting both GRP- and VPAC1-Receptors concomitantly overexpressed on various malignancies – Is the concept feasible? Eur J Med Chem. 2018;155:84–95.10.1016/j.ejmech.2018.05.047Search in Google Scholar PubMed
[49] Moody TW, Nuche-Berenguer B, Jensen RT. Vasoactive intestinal peptide/pituitary adenylate cyclase activating polypeptide, and their receptors and cancer. Curr OpEndocrinol, Diabetes Obes. 2016;23(1):38–47.10.1097/MED.0000000000000218Search in Google Scholar PubMed PubMed Central
[50] Nguyen TD. Vasoactive Intestinal Peptide (VIP). In: Johnson LR, editor. Encyclopedia of gastroenterology. New York: Elsevier; 2004. p. 604–10.10.1016/B0-12-386860-2/00713-9Search in Google Scholar
[51] Klippstein R, Pozo D. Chapter five – Vasoactive intestinal peptide (VIP) nanoparticles for diagnostics and for controlled and targeted drug delivery. In: Donev R, editor. Advances in protein chemistry and structural biology. Vol. 98. Waltham, MA, USA: Academic Press; 2015. p. 145–68.10.1016/bs.apcsb.2014.11.006Search in Google Scholar PubMed
[52] Hamley IW. Introduction to peptide science. Hoboken, NJ, USA: John Wiley & Sons; 2020.Search in Google Scholar
[53] Kyte J, Doolittle RF. A simple method for displaying the hydropathic character of a protein. J Mol Biol. 1982;157(1):105–32.10.1016/0022-2836(82)90515-0Search in Google Scholar
[54] Abbruzzetti S, Sottini S, Viappiani C, Corrie JET. Acid-induced unfolding of myoglobin triggered by a laser pH-jump method. Photochem Photobiol Sci. 2006;5:621–8.10.1039/b516533dSearch in Google Scholar PubMed
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