Regioselective synthesis and photophysical and electrochemical studies of 20-substituted cyanine dye-purpurinimide conjugates: incorporation of Ni(II) into the conjugate enhances its tumor-uptake and fluorescence-imaging ability.

We report herein a simple and efficient approach to the synthesis of a variety of meso-substituted purpurinimides. The reaction of meso-substituted purpurinimide with N-bromosuccinimide regioselectively introduced a bromo functionality at the 20-position, which on further reaction with a variety of boronic acids under Suzuki reaction conditions yielded the corresponding meso-substituted analogues. Interestingly, the free base and the metalated analogues showed remarkable differences in photosensitizing efficacy (PDT) and tumor-imaging ability. For example, the free-base conjugate showed significant in vitro PDT efficacy, but limited tumor avidity in mice bearing tumors, whereas the corresponding Ni(II) derivative did not produce any cell kill, but showed excellent tumor-imaging ability at a dose of 0.3 µmol kg(-1) at 24, 48, and 72 h post-injection. The limited PDT efficacy of the Ni(II) analogue could be due to its inability to produce singlet oxygen, a key cytotoxic agent required for cell kill in PDT. Based on electrochemical and spectroelectrochemical data in DMSO, the first one-electron oxidation (0.52 V vs. SCE) and the first one-electron reduction (-0.57-0.67 V vs. SCE) of both the free base and the corresponding Ni(II) conjugates are centered on the cyanine dye, whereas the second one-electron reduction (-0.81 V vs. SCE) of the two conjugates is assigned to the purpurinimide part of the molecule. Reduction of the cyanine dye unit is facile and occurs prior to reduction of the purpurinimide group, which suggests that the cyanine dye unit as an oxidant could be the driving force for quenching of the excited triplet state of the molecules. An interaction between the cyanine dye and the purpurinimide group is clearly observed in the free-base conjugate, which compares with a negligible interaction between the two functional groups in the Ni(II) conjugate. As a result, the larger HOMO-LUMO gap of the free-base conjugate and the corresponding smaller quenching constant is a reason to decrease the intramolecular quenching process and increase the production of singlet oxygen to some degree.

Reactive intermediates produced from the metabolism of the vanilloid ring of capsaicinoids by p450 enzymes.

This study characterized electrophilic and radical products derived from the metabolism of capsaicin by cytochrome P450 and peroxidase enzymes. Multiple glutathione and ß-mercaptoethanol conjugates (a.k.a., adducts), derived from the trapping of quinone methide and quinone intermediates of capsaicin, its analogue nonivamide, and O-demethylated and aromatic hydroxylated metabolites thereof, were produced by human liver microsomes and individual recombinant human P450 enzymes. Conjugates derived from concomitant dehydrogenation of the alkyl terminus of capsaicin were also characterized. Modifications to the 4-OH substituent of the vanilloid ring of capsaicinoids largely prevented the formation of electrophilic intermediates, consistent with the proposed structures and mechanisms of formation for the various conjugates. 5,5'-Dicapsaicin, presumably arising from the bimolecular coupling of free radical intermediates was also characterized. Finally, the analysis of hepatic glutathione conjugates and urinary N-acetylcysteine conjugates from mice dosed with capsaicin confirmed the formation of glutathione conjugates of O-demethylated quinone methide and 5-OH-capsaicin in vivo. These data demonstrated that capsaicin and structurally similar analogues are converted to reactive intermediates by certain P450 enzymes, which may partially explain conflicting reports related to the cytotoxic, pro-carcinogenic, and chemoprotective effects of capsaicinoids in different cells and/or organ systems.

Synthesis, photophysical and electrochemistry of near-IR absorbing bacteriochlorins related to bacteriochlorophyll a.

A series of new bacteriochlorins was synthesized using 13(2)-oxo-bacteriopyropheophorbide a (derived from bacteriochlorophyll a) as a starting material, which on reacting with o-phenylenediamine and 1,10-diaminonaphthalene afforded highly conjugated annulated bacteriochlorins with fused quinoxaline, benzimidazole, and perimidine rings, respectively. The absorption spectra of these novel bacteriochlorins demonstrated remarkably red-shifted intense Q(y) absorption bands observed in the range of 816-850 nm with high molar extinction coefficients (89,900-136,800). Treatment of 13(2)-oxo-bacteriopyropheophorbide a methyl ester with diazomethane resulted in the formation of bacterioverdins containing a fused six-membered methoxy-substituted cyclohexenone (verdin) as an isomeric mixture. The pure isomers which exhibit long-wavelength absorptions in the near-IR region (865-890 nm) are highly stable at room temperature with high reactivity with O(2) at the triplet photoexcited state and favorable redox potential and could be potential candidates for use as photosensitizers in photodynamic therapy (PDT).

The role of porphyrin chemistry in tumor imaging and photodynamic therapy.

In recent years several review articles and books have been published on the use of porphyrin-based compounds in photodynamic therapy (PDT). This critical review is focused on (i) the basic concept of PDT, (ii) advantages of long-wavelength absorbing photosensitizers (PS), (iii) a brief discussion on recent advances in developing PDT agents, and (iv) the various synthetic strategies designed at the Roswell Park Cancer Institute, Buffalo, for developing highly effective long-wavelength PDT agents and their utility in constructing the conjugates with tumor-imaging and therapeutic potential (Theranostics). The clinical status of certain selected PDT agents is also summarized (205 references).

Charged groups on pyropheophorbide-based photosensitizers dictate uptake by tumor cells and photodynamic therapy efficacy.

This study investigated the impact of anionic and cationic substituents of the pyropheophorbide-based photosensitizers (PS) on uptake and retention by tumor epithelial cells and photodynamic therapy (PDT). A series of PSs were generated that bear carboxylic acid functionalities, alkyl amines with variable length of carbon units or as a quaternary ammonium salt introduced at position 172 of 3-(1'-hexyloxy)ethyl-3-devinylpyropheophorbide-a (HPPH). The nature of the functionalities in the macrocycle made a significant difference in overall lipophilicity (log D values at pH 7.4), and in binding to and retention by human and murine tumor cells. Depending on the presence of functional groups, the PSs showed a change in cellular uptake from diffusion to endocytosis and in the preference for subcellular localization to mitochondria/ER or lysosomes. Two and more carboxylic groups drastically reduced uptake by all cell types. In contrast, PSs with amine and quaternary amine salt showed higher cellular binding, uptake and in vitro PDT efficacy than HPPH. The enhanced cellular uptake of the cationic PSs was accompanied by a loss of tumor cell specificity and contributed to severe systemic toxicity in tumor-bearing mice intravenously injected with the PS and subjected to investigate their therapeutic potential.

Structure-activity relationship of capsaicin analogs and transient receptor potential vanilloid 1-mediated human lung epithelial cell toxicity.

Activation of intracellular transient receptor potential vanilloid-1 (TRPV1) in human lung cells causes endoplasmic reticulum (ER) stress, increased expression of proapoptotic GADD153 (growth arrest- and DNA damage-inducible transcript 3), and cytotoxicity. However, in cells with low TRPV1 expression, cell death is not inhibited by TRPV1 antagonists, despite preventing GADD153 induction. In this study, chemical variants of the capsaicin analog nonivamide were synthesized and used to probe the relationship between TRPV1 receptor binding, ER calcium release, GADD153 expression, and cell death in TRPV1-overexpressing BEAS-2B, normal BEAS-2B, and primary normal human bronchial epithelial lung cells. Modification of the 3-methoxy-4-hydroxybenzylamide vanilloid ring pharmacophore of nonivamide reduced the potency of the analogs and rendered several analogs mildly inhibitory. Correlation analysis of analog-induced calcium flux, GADD153 induction, and cytotoxicity revealed a direct relationship for all three endpoints in all three lung cell types for nonivamide and N-(3,4-dihydroxybenzyl)nonanamide. However, the N-(3,4-dihydroxybenzyl)nonanamide analog also produced cytotoxicity through redox cycling/reactive oxygen species formation, shown by inhibition of cell death by N-acetylcysteine. Molecular modeling of binding interactions between the analogs and TRPV1 agreed with data for reduced potency of the analogs, and only nonivamide was predicted to form a "productive" ligand-receptor complex. This study provides vital information on the molecular interactions of capsaicinoids with TRPV1 and substantiates TRPV1-mediated ER stress as a conserved mechanism of lung cell death by prototypical TRPV1 agonists.

Synthesis, photophysical, electrochemical, tumor-imaging, and phototherapeutic properties of purpurinimide-N-substituted cyanine dyes joined with variable lengths of linkers.

Purpurinimide methyl esters, bearing variable lengths of N-substitutions, were conjugated individually to a cyanine dye with a carboxylic acid functionality. The results obtained from in vitro and in vivo studies showed a significant impact of the linkers joining the phototherapeutic and fluorescence imaging moieties. The photosensitizer-fluorophore conjugate with a PEG linker showed the highest uptake in the liver, whereas the conjugate linked with two carbon units showed excellent tumor-imaging and PDT efficacy at 24 h postinjection. Whole body imaging and biodistribution studies at variable time points portrayed enhanced fluorescent uptake of the conjugates in the tumor compared to that in the skin. Interestingly, the conjugate with the shortest linker and the one joining with two carbon units showed faster clearance from normal organs, e.g., the liver, kidney, spleen, and lung, compared to that in tumors. Both imaging and PDT efficacy of the conjugates were performed in BALB/c mice bearing Colon26 tumors. Compared to the others, the short linker conjugate showed poor tumor fluorescent properties and as a corollary does not exhibit the dual functionality of the photosensitizer-fluorophore conjugate. For this reason, it was not evaluated for in vivo PDT efficacy. However, in Colon26 tumor cells (in vitro), the short linker was highly effective. Among the conjugates with variable linkers, the rate of energy transfer from the purpurinimide moiety to the cyanine moiety increased with deceasing linker length, as examined by femtosecond laser flash photolysis measurements. No electron transfer from the purpurinimide moiety to the singlet excited state of the cyanine moiety or from the singlet excited state of the cyanine moiety to the purpurinimide moiety occurred as indicated by a comparison of transient absorption spectra with spectra of the one-electron oxidized and one-electron reduced species of the conjugate obtained by spectroelectrochemical measurements.

Conjugation of cRGD peptide to chlorophyll a based photosensitizer (HPPH) alters its pharmacokinetics with enhanced tumor-imaging and photosensitizing (PDT) efficacy.

The α(v)ß(3) integrin receptor plays an important role in human metastasis and tumor-induced angiogenesis. Cyclic Arg-Gly-Asp (cRGD) peptide represents a selective α(v)ß(3) integrin ligand that has been extensively used for research, therapy, and diagnosis of neoangiogenesis. For developing photosensitizers with enhanced PDT efficacy, we here report the synthesis of a series of bifunctional agents in which the 3-(1'-hexyloxyethyl)-3-devinylpyropheophorbide a (HPPH), a chlorophyll-based photosensitizer, was conjugated to cRGD and the related analogues. The cell uptake and in vitro PDT efficacy of the conjugates were studied in α(v)ß(3) integrin overexpressing U87 and 4T1 cell lines whereas the in vivo PDT efficacy and fluorescence-imaging potential of the conjugates were compared with the corresponding nonconjugated photosensitizer HPPH in 4T1 tumors. Compared to HPPH, the HPPH-cRGD conjugate in which the arginine and aspartic acid moieties were available for binding to two subunits of α(v)ß(3) integrin showed faster clearance, enhanced tumor imaging and enhanced PDT efficacy at 2-4 h postinjection. Molecular modeling studies also confirmed that the presence of the HPPH moiety in HPPH-cRGD conjugate does not interfere with specific recognition of cRGD by α(v)ß(3) integrin. Compared to U87 and 4T1 cells the HPPH-cRGD showed significantly low photosensitizing efficacy in A431 (α(v)ß(3) negative) tumor cells, suggesting possible target specificity of the conjugate.

Synthesis, spectroscopic, and in vitro photosensitizing efficacy of ketobacteriochlorins derived from ring-B and ring-D reduced chlorins via pinacol-pinacolone rearrangement.

In this report, we present a regioselective oxidation of a series bacteriochlorins, which on reacting with either ferric chloride (FeCl(3)) or 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) yielded the corresponding ring-B or ring-D reduced chlorins. The effect of the number of electron-withdrawing groups present at the peripheral position, with or without a fused isocyclic ring (ring-E), did not make any significant difference in regioselective oxidation of the pyrrole rings. However, depending on the nature of substituents, the intermediate bis-dihydroxy bacteriochlorins on subjecting to pinacol-pinacolone reaction conditions gave various ketochlorins. The introduction of the keto-group at a particular position in the molecule possibly depends on the stability of the intermediate carbocation species. The newly synthesized bacteriochlorins show strong long-wavelength absorption and produced significant in vitro (Colon26 cells) photosensitizing ability. Among the compounds tested, the bacteriochlorins containing a keto-group at position 7 of ring-B with cleaved five-member isocyclic ring showed the best efficacy.

Novel methods to incorporate photosensitizers into nanocarriers for cancer treatment by photodynamic therapy.

OBJECTIVE: A hydrophobic photosensitizer, 2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH), was loaded into nontoxic biodegradable amine functionalized polyacrylamide (AFPAA) nanoparticles using three different methods (encapsulation, conjugation, and post-loading), forming a stable aqueous dispersion. Each formulation was characterized for physicochemical properties as well as for photodynamic performance so as to determine the most effective nanocarrier formulation containing HPPH for photodynamic therapy (PDT). MATERIALS AND METHODS: HPPH or HPPH-linked acrylamide was added into monomer mixture and polymerized in a microemulsion for encapsulation and conjugation, respectively. For post-loading, HPPH was added to an aqueous suspension of pre-formed nanoparticles. Those nanoparticles were tested for optical characteristics, dye loading, dye leaching, particle size, singlet oxygen production, dark toxicity, in vitro photodynamic cell killing, whole body fluorescence imaging and in vivo PDT. RESULTS: HPPH was successfully encapsulated, conjugated or post-loaded into the AFPAA nanoparticles. The resultant nanoparticles were spherical with a mean diameter of 29 ± 3 nm. The HPPH remained intact after entrapment and the HPPH leaching out of nanoparticles was negligible for all three formulations. The highest singlet oxygen production was achieved by the post-loaded formulation, which caused the highest phototoxicity in in vitro assays. No dark toxicity was observed. Post-loaded HPPH AFPAA nanoparticles were localized to tumors in a mouse colon carcinoma model, enabling fluorescence imaging, and producing a similar photodynamic tumor response to that of free HPPH in equivalent dose. CONCLUSIONS: Post-loading is the promising method for loading nanoparticles with hydrophobic photosensitizers to achieve effective in vitro and in vivo PDT.

Investigating the elusive mechanism of glycosaminoglycan biosynthesis.

Glycosaminoglycan (GAG) biosynthesis requires numerous biosynthetic enzymes and activated sulfate and sugar donors. Although the sequence of biosynthetic events is resolved using reconstituted systems, little is known about the emergence of cell-specific GAG chains (heparan sulfate, chondroitin sulfate, and dermatan sulfate) with distinct sulfation patterns. We have utilized a library of click-xylosides that have various aglycones to decipher the mechanism of GAG biosynthesis in a cellular system. Earlier studies have shown that both the concentration of the primers and the structure of the aglycone moieties can affect the composition of the newly synthesized GAG chains. However, it is largely unknown whether structural features of aglycone affect the extent of sulfation, sulfation pattern, disaccharide composition, and chain length of GAG chains. In this study, we show that aglycones can switch not only the type of GAG chains, but also their fine structures. Our findings provide suggestive evidence for the presence of GAGOSOMES that have different combinations of enzymes and their isoforms regulating the synthesis of cell-specific combinatorial structures. We surmise that click-xylosides are differentially recognized by the GAGOSOMES to generate distinct GAG structures as observed in this study. These novel click-xylosides offer new avenues to profile the cell-specific GAG chains, elucidate the mechanism of GAG biosynthesis, and to decipher the biological actions of GAG chains in model organisms.

Hexylether derivative of pyropheophorbide-a (HPPH) on conjugating with 3gadolinium(III) aminobenzyldiethylenetriaminepentaacetic acid shows potential for in vivo tumor imaging (MR, Fluorescence) and photodynamic therapy.

Conjugates of 3-(1'-hexyloxyethyl)-3-devinyl pyropheophorbide-a (HPPH) with multiple Gd(III)aminobenzyl diethylenetriamine pentacetic acid (ADTPA) moieties were evaluated for tumor imaging and photodynamic therapy (PDT). In vivo studies performed in both mice and rat tumor models resulted in a significant MR signal enhancement of tumors relative to surrounding tissues at 24 h postinjection. The water-soluble (pH: 7.4) HPPH-3Gd(III) ADTPA conjugate demonstrated high potential for tumor imaging by MR and fluorescence. This agent also produced long-term tumor cures via PDT. An in vivo biodistribution study with the corresponding (14)C-analogue also showed significant tumor uptake 24 h postinjection. Toxicological evaluations of HPHH-3Gd(III)ADTPA administered at and above imaging/therapeutic doses did not show any evidence of organ toxicity. Our present study illustrates a novel approach for the development of water-soluble "multifunctional agents", demonstrating efficacy for tumor imaging (MR and fluorescence) and phototherapy.

Synthesis of Tumor-avid Photosensitizer-Gd(III)DTPA conjugates: impact of the number of gadolinium units in T1/T2 relaxivity, intracellular localization, and photosensitizing efficacy.

To develop novel bifunctional agents for tumor imaging (MR) and photodynamic therapy (PDT), certain tumor-avid photosensitizers derived from chlorophyll-a were conjugated with variable number of Gd(III)aminobenzyl DTPA moieties. All the conjugates containing three or six gadolinium units showed significant T(1) and T(2) relaxivities. However, as a bifunctional agent, the 3-(1'-hexyloxyethyl)pyropheophorbide-a (HPPH) containing 3Gd(III) aminophenyl DTPA was most promising with possible applications in tumor-imaging and PDT. Compared to HPPH, the corresponding 3- and 6Gd(III)aminobenzyl DTPA conjugates exhibited similar electronic absorption characteristics with a slightly decreased intensity of the absorption band at 660 nm. However, compared to HPPH, the excitation of the broad "Soret" band (near 400 nm) of the corresponding 3Gd(III)aminobenzyl-DTPA analogues showed a significant decrease in the fluorescence intensity at 667 nm.

Pluronic F-127: An Efficient Delivery Vehicle for 3-(1'-hexyloxy)ethyl-3-devinylpyropheophorbide-a (HPPH or Photochlor).

To determine the impact of delivery vehicles in photosensitizing efficacy of HPPH, a hydrophobic photosensitizer was dissolved in various formulations: 1% Tween 80/5% dextrose, Pluronic P-123 and Pluronic F-127 in 0.5%, 1% and 2% phosphate buffer solutions (PBS). HPPH was also conjugated to Pluronic F-127, and the resulting conjugate (PL-20) was formulated in PBS. Among the different delivery vehicles, only Pluronic P-123 displayed significant vehicle cytotoxicity, whereas Pluronic F127 was nontoxic. Compared to PL-20, HPPH formulated in Tween80 and Pluronic F-127 showed higher cell-uptake, but lower long-term retention in Colon26 cell compared to PL-20. The higher retention of PL-20 was similarly observed during in vivo uptake with BALB/c mice baring Ct26 tumors. In contrast to the in vitro uptake experiments, PL-20 showed slightly higher uptake compared to HPPH formulated in Tween or Pluronic-F127. A significant difference in pharmacokinetic profile was also observed between the HPPH-Pluronic formulation and PL-20. Under similar in vivo treatment parameters (drug dose 0.47 µmol kg-1 , light dose: 135 J cm-2 at 24 h post-injection of PS), HPPH formulated either in Tween or Pluronic F-127 formulation showed similar in vivo PDT efficacy (20-30% tumor cure on day 60), whereas PL-20 showed 40% tumor cure (day 60).

Remarkable features of the McMurry reaction conditions in dimerization of formyl- and 2-formylvinylpurpurinimides. Electrochemistry of monomeric Ni(II) purpurinimide and the corresponding dyads.

To investigate the electrochemical properties of purpurinimide dyads and electron transfer sites for their reduction and oxidation, a series of dimers with variable C-C linkages were synthesized. For the preparation of these novel structures, the formyl and 2-formylvinyl substituents were regioselectively introduced at positions 3 and 20 of Ni(II) purpurinimides by the Vilsmeier reaction. The Ni(II) complexes were then subjected to the McMurry reaction under two different conditions with unexpected results. For example, the reaction of formyl purpurinimides with TiCl(3)(DME)(1.5) failed to produce the desired C-C dimers, and the starting compounds were recovered almost quantitatively. Under similar reaction conditions, the 20-(2-formylvinyl)purpurinimide also did not dimerize but produced instead unexpected benzoisobacteriochlorins via an intramolecular cyclization. However, treatment of the 3-formyl- and 20-formylpurpurinimides with TiCl(4)/Zn produced corresponding dimers linked with one double bond (trans) in modest yields. Under similar conditions, Ni(II) purpurinimides containing a 2-formylvinyl substituent either at position 3 or at position 20 afforded the respective C-C dimers, where the purpurinimide moieties were joined with a trans-trans-trans hexatriene linker. Molecular modeling data suggest that the nature of the conformational energy difference found in all trans vs trans-cis-trans conformers of the dimers connected by a hexatriene linker at the meso- or beta-position of the macrocycle is not because of the intrinsic conformational energy difference of the linker region, which is identical for both dimers.

Highly selective synthesis of the ring-B reduced chlorins by ferric chloride-mediated oxidation of bacteriochlorins: effects of the fused imide vs isocyclic ring on photophysical and electrochemical properties.

The oxidation of bacteriopyropheophorbide with ferric chloride hexahydrate or its anhydrous form produced the ring-D oxidized (ring-B reduced) chlorin in >95% yield. Replacing the five-member isocyclic ring in bacteriopyropheophorbide- a with a fused six-member N-butylimide ring system made no difference in regioselective oxidation, and the corresponding ring-B reduced chlorin was isolated in almost quantitative yield. When the oxidant was replaced by 2,3-dichloro-5,6-dicyano-p-benzoquinone, which is frequently used at the oxidizing stage of the porphyrin synthesis, the ring-B oxidized (ring-D reduced) chlorins were obtained. With both ring-B reduced and ring-D reduced chlorins in hand, their photophysical and electrochemical properties were examined and compared for the first time. The ring-B reduced chlorine 20, with a fused six-member N-butylimide ring, exhibits the most red-shifted absorption band (at lambda(max) = 746 nm), the lowest fluorescence quantum yield (4.5%), and the largest quantum yield of singlet oxygen formation (67%) among the reduced ring-B and ring-D chlorins investigated in this study. Measurements of the one-electron oxidation and reduction potentials show that compound 20 is also the easiest to oxidize among the examined compounds and the third easiest to reduce. In addition, the 1.62 eV HOMO-LUMO gap of 20 is the smallest of the examined compounds, and this agrees with values calculated using the DFT method. Spectroelectrochemical measurements afforded UV-visible absorption spectra for both the radical cations and radical anions of the examined chlorins. The ring-B reduced compound 20, with a fused six-member N-butylimide ring, is regarded as the most promising candidate in this study for photodynamic therapy because it has the longest wavelength absorption and the largest quantum yield of singlet oxygen formation among the compounds investigated.

Formation of five-membered carbocycles by intramolecular palladium-catalyzed ring opening of tert-cyclobutanols.

We report herein stereoselective formation of a functionalized five-membered carbocycle bearing a quaternary center by intramolecular palladium-catalyzed ring-opening of o-bromophenyl-tethered tert-cyclobutanols.

Targeting the C-terminal focal adhesion kinase scaffold in pancreatic cancer.

Preliminary studies in our laboratory have demonstrated the importance of both the NH2 and COOH terminus scaffolding functions of focal adhesion kinase (FAK). Here, we describe a new small molecule inhibitor, C10, that targets the FAK C-terminus scaffold. C10 showed marked selectivity for cells overexpressing VEGFR3 when tested in isogenic cell lines, MCF7 and MCF7-VEGFR3. C10 preferentially inhibited pancreatic tumor growth in vivo in cells with high FAK-Y925 and VEGFR3 expression. Treatment with C10 led to a significant inhibition in endothelial cell proliferation and tumor endothelial and lymphatic vessel density and decrease in interstitial fluid pressure. These results highlight the underlying importance of targeting the FAK scaffold to treat human cancers.

Polyacrylamide-based biocompatible Nanoplatform enhances the tumor uptake, PET/fluorescence imaging and anticancer activity of a chlorophyll analog.

In this report we demonstrate the outstanding advantages of multifunctional nanoplatforms for cancer-imaging and therapy. The non-toxic polyacrylamide (PAA) nanoparticles (size:18-25 nm) formulation drastically changed the pharmacokinetic profile of the ¹²4I- labeled chlorophyll-a derivative (formulated in 10% ethanol in PBS) with a remarkable enhancement in tumor uptake, and significantly reduced uptake in spleen and liver. Among the various nanoformulations investigated, the ¹²4I- labeled photosensitizer (dose: 0.6142 MBq), and the cyanine dye-nanoparticles (CD-NP) conjugate (dose 0.3 µmol/kg) in combination showed great potential for tumor imaging (PET/NIR fluorescence) in BALB/c mice bearing Colon26 tumors. Compared to free non-labeled photosensitizer, the corresponding PAA nanoformulation under similar treatment parameters showed a remarkable enhancement in long-term tumor cure by PDT (photodynamic therapy) and provides an opportunity to develop a single nanoplatform for tumor-imaging (PET/fluorescence) and phototherapy, a practical "See and Treat" approach.

Design, synthesis, and biological evaluation of novel FAK scaffold inhibitors targeting the FAK-VEGFR3 protein-protein interaction.

Focal adhesion kinase (FAK) and vascular endothelial growth factor receptor 3 (VEGFR3) are tyrosine kinases, which function as key modulators of survival and metastasis signals in cancer cells. Previously, we reported that small molecule chlorpyramine hydrochloride (C4) specifically targets the interaction between FAK and VEGFR3 and exhibits anti-tumor efficacy. In this study, we designed and synthesized a series of 1 (C4) analogs on the basis of structure activity relationship and molecular modeling. The resulting new compounds were evaluated for their binding to the FAT domain of FAK and anti-cancer activity. Amongst all tested analogs, compound 29 augmented anti-proliferative activity in multiple cancer cell lines with stronger binding to the FAT domain of FAK and disrupted the FAK-VEGFR3 interaction. In conclusion, we hope that this work will contribute to further studies of more potent and selective FAK-VEGFR3 protein-protein interaction inhibitors.