Photosensitizer effect of 9-hydroxypheophorbide α on diode laser-irradiated laryngeal cancer cells: Oxidative stress-directed cell death and migration suppression

Cu(II) flavonoids as potential photochemotherapeutic agents

Flavonoids, naturally derived polyphenolic compounds, have received significant attention due to their remarkable biochemical properties that offer substantial health benefits to humans. In this work, a series of six Cu(II) flavonoid complexes of the formulation [Cu(L1)(L2)](ClO4) where L1 is 3-hydroxy flavone (HF1, 1 and 4), 4-fluoro-3-hydroxy flavone (HF2, 2 and 5), and 2,6-difluoro-3-hydroxy flavone (HF3, 3 and 6); L2 is 1,10-phenanthroline (phen, 1-3) and 2-(anthracen-1-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (aip, 4-6) were successfully synthesized, fully characterized and also evaluated for their in vitro photo-triggered cytotoxicity in cancer cells. The single-crystal X-ray diffraction structure of complex 2 shows square pyramidal geometry around the Cu(II) center. The complexes 1-6 showed quasi-reversible cyclic voltammetric responses for the Cu(II)/Cu(I) couple at ∼-0.230 V with a very large ΔEp value of ∼350-480 mV against the Ag/AgCl reference electrode in DMF-0.1 M tetrabutylammonium perchlorate (TBAP) at a scan rate of 50 mV s-1. The complexes were found to have considerable binding propensity for human serum albumin (HSA) and calf thymus DNA (ct-DNA). The complexes displayed remarkable dose-dependent photocytotoxicity in visible light (400-700 nm) in both A549 (human lung cancer) and MCF-7 (human breast cancer) cell lines while remaining significantly less toxic in darkness. They were found to be much less toxic to HPL1D (immortalized human peripheral lung epithelial) normal cells compared to A549 and MCF-7 cancer cells. Upon exposure to visible light, they generate reactive oxygen species, which are thought to be the main contributors to the death of cancer cells. In the presence of visible light, the complexes predominantly elicit an apoptotic mode of cell death. Complex 6 preferentially localizes in the mitochondria of A549 cells.

An "IgG-hitchhiking" approach for rapid tumor accumulation and clearance of photosensitizers

Photodynamic therapy (PDT) has been widely used for the local treatment of a variety of cancer. To improve the therapeutic effect, delicate nanoparticles loading photosensitizers (PSs) have been designed to improve the accumulation of PSs in tumor. Different from the anti-cancer drugs for chemotherapy or immunotherapy, the delivery of PSs requires rapid tumor accumulation followed by quick elimination to reduce the potential risk of phototoxicity. However, owing to the nature of prolonged blood circulation of the nanoparticles, the conventional nanoparticulate delivery systems may decelerate the clearance of PSs. Here, we present a tumor-targeted delivery approach termed "IgG-hitchhiking" strategy through a self-assembled PSs nanostructure, according to the intrinsic binding between the photosensitizer pheophorbide A (PhA) and immunoglobulin (IgG). We utilize the intravital fluorescence microscopic imaging to uncover that the nanostructures (IgG:PhA NPs) increase the extravasation of PhA into tumor within the first hour post intravenous injection compared with free PhA, correlating with an improved efficacy of PDT. After ∼1 h post-injection, a quick decrease in the PhA amount in the tumor is observed, while the tumor IgG level is continuously increasing. The disparity of the tumor distribution between PhA and IgG allows the quick elimination of the PSs for minimized skin phototoxicity. Our results provide a direct evidence of the enhanced accumulation and elimination of the PSs in the tumor microenvironment through the "IgG-hitchhiking" approach. This strategy presents a promising tumor-targeted delivery approach for the PSs in lieu of the existing strategy for enhanced PDT with minimal toxicity in clinic.

Copper(ii) curcumin complexes for endoplasmic reticulum targeted photocytotoxicity

Three copper(ii) complexes viz. [Cu(cur)(L)(ClO4)] (1-3), where Hcur is curcumin and L is 1,10-phenanthroline (phen, 1), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq, 2), or dipyrido[3,2-a:2',3'-c]phenazine (dppz, 3) were synthesized, fully characterized by various physicochemical methods and evaluated for their light-assisted chemotherapeutic potential. The complexes [Cu(acac)(L)(ClO4)] (4-6), where Hacac is acetylacetone and L is phen (in 4), dpq (in 5) and dppz (in 6), were synthesized and used as controls. The solid state structures of complexes 4 and 5 were determined by single crystal X-ray diffraction. The curcumin complexes (1-3) were redox inactive at the copper centre, whereas the acetylacetonato complexes (4-6) displayed a Cu(ii)/Cu(i) couple at ∼0.1 V vs. Ag/AgCl reference electrode in DMF. Complexes 1-3 showed an intense curcumin-based band at ∼440 nm in DMF-Tris-HCl buffer (pH = 7.2) (1 : 9 v/v) which masks the copper based d-d band. The complexes bind to human serum albumin (HSA) with moderate efficacy. They also displayed significant binding affinity for calf-thymus (CT) DNA. The lipophilic curcumin complexes show remarkable visible light induced cytotoxicity (IC50 = ∼4 μM) with high phototoxic indices (PI) with low dark toxicity in human cervical carcinoma (HeLa) and human lung carcinoma (A549) cells. The corresponding acetylacetonato controls (4-6) did not show significant cytotoxicity in the dark or light. DCFDA and annexin V-FITC/PI assays using flow cytometry confirm the induction of significant apoptosis in cancer cells via generation of cytotoxic reactive oxygen species upon photoactivation. Confocal microscopic images using complex 3 demonstrate localization of the complexes predominantly in the endoplasmic reticulum of HeLa cells.

Ni(II) curcumin complexes for cellular imaging and photo-triggered in vitro anticancer activity

Nickel(II) complexes [Ni(cur)(L)₂](OAc) (1-3) where L is N,N-donor heterocyclic bases namely 1,10-phenanthroline (phen in 1), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq in 2), dipyrido[3,2-a:2',3'-c]phenazine (dppz in 3) and Hcur is curcumin were prepared, fully characterized and light-induced in vitro anticancer activity studied. Three nickel(II) complexes containing acetylacetonato (Hacac) ligand, viz.[Ni(acac)(L)₂](OAc) (4-6) where L is phen (in 4), dpq (in 5), dppz (in 6) were prepared and used as controls. Complex 4 was structurally characterized by single crystal X-ray diffraction technique, which revealed an octahedral NiN₄O₂ geometry around the metal centre. Complexes 1-3 showed an intense curcumin-based band at ∼440 nm in DMSO-Tris-HCl buffer (pH = 7.2) (1:4 v/v) which masks the nickel based d-d band. The curcumin comlexes (1-3) were redox inactive at the nickel centre, whereas the acetylacetonato complexes (4-6) displayed an irreversible voltammetric response at ∼1.00 V vs. Ag/AgCl reference electrode in DMF. The complexes bind to calf thymus DNA (ct-DNA) with considerable affinity and interacted with human serum albumin (HSA) with moderate affinity. The Ni(II) curcumin complexes display significant in vitro light-induced cytotoxicity in HeLa (human cervical carcinoma) and A549 (lung cancer cells) involving reactive oxygen species (ROS), with very low dark toxicity. The complexes were found to be much less toxic to immortalized lung epithelial normal cells (HPL1D). Confocal microscopic images using complex 2 and 3 showed that they primarily localize in the cytosol of A549 cells. The mechanism of cell death is mainly apoptosis in nature showing arrest of sub-G1 phase of cell cycle progression in A549 cells under visible light exposure and involves significant loss of mitochondrial membrane potential as observed from JC-1 assay.

miR-147a suppresses the metastasis of non-small-cell lung cancer by targeting CCL5

Objective

MicroRNA (miR)-147a acts as an inhibitory miRNA in many cancers. However, its potential roles in non-small-cell lung cancer (NSCLC) remain unclear.

Methods

Levels of miR-147a and C-C motif chemokine ligand 5 (CCL5) were measured using a quantitative real-time PCR assay. Cell growth, migration, and invasion of NSCLC cells were assessed by colony formation, wound healing, and Transwell invasion assays, respectively. The role of miR-147a in the growth and metastatic ability of NSCLC in vivo was detected using a xenograft model and experimental lung metastasis model.

Results

miR-147a was downregulated in NSCLC cell lines as well as in tissues. Gain-of-function and loss-of-function analyses demonstrated that upregulation of miR-147a decreased the aggressiveness of NSCLC cells in vitro. In addition, CCL5 was identified as a target of miR-147a. We also demonstrated the effect of miR-147a in the progression of NSCLC cells via targeting CCL5. Finally, the in vivo mouse xenograft model showed that miR-147a inhibited progression of NSCLC cells.

Conclusions

Overall, expression of miR-147a was downregulated in NSCLC. Importantly, upregulation of miR-147a suppressed the growth and metastasis of NSCLC cells in vivo by targeting CCL5.

Near Infrared-Activated Dye-Linked ZnO Nanoparticles Release Reactive Oxygen Species for Potential Use in Photodynamic Therapy

Novel dye-linked zinc oxide nanoparticles (NPs) hold potential as photosensitizers for biomedical applications due to their excellent thermal- and photo-stability. The particles produced reactive oxygen species (ROS) upon irradiation with 850 nm near infrared (NIR) light in a concentration- and time-dependent manner. Upon irradiation, ROS detected in vitro in human umbilical vein endothelial cells (HUVEC) and human carcinoma MCF7 cells positively correlated with particle concentration and interestingly, ROS detected in MCF7 was higher than in HUVEC. Preferential cytotoxicity was also exhibited by the NPs as cell killing was higher in MCF7 than in HUVEC. In the absence of irradiation, dye-linked ZnO particles minimally affected the viability of cell (HUVEC) at low concentrations (<30 μg/mL), but viability significantly decreased at higher particle concentrations, suggesting a need for particle surface modification with poly (ethylene glycol) (PEG) for improved biocompatibility. The presence of PEG on particles after dialysis was indicated by an increase in size, an increase in zeta potential towards neutral, and spectroscopy results. Cell viability was improved in the absence of irradiation when cells were exposed to PEG-coated, dye-linked ZnO particles compared to non-surface modified particles. The present study shows that there is potential for biological application of dye-linked ZnO particles in photodynamic therapy.

Oxidative stress induced by carboplatin promotes apoptosis and inhibits migration of HN-3 cells

Laryngeal squamous cell carcinoma (LSCC) is currently a serious public health problem in China; thus, it is urgent to identify effective treatment strategies for this disease. Previous studies demonstrated that reactive oxygen species (ROS) serve important roles in the apoptosis of LSCC cells. It has also been indicated that carboplatin (CBDCA), a second-generation platinum compound with broad antineoplastic properties, is able to induce oxidative stress to produce ROS, which in turn promotes apoptosis. Thus, the present study investigated if CBDCA is cytotoxic in LSCC cells due to the oxidative stress caused by ROS. Therefore, an MTT assay was performed to determine the cell viability of HN-3 LSCC cells following treatment with different doses of CBDCA. Subsequently, the expression levels of ROS and the rate of apoptosis/necrosis were evaluated in the cells. Following this, the HN-3 cells were co-treated with CBDCA and glutathione (GSH) or H₂O2, followed by an MTT assay, a cell migration assay and western blot analysis. The results demonstrated that CBDCA reduced the viability of HN-3 cells in a time- and dose-dependent manner and promoted the production of ROS and apoptosis at certain doses. Additionally, the combination treatment of CBDCA and H2O2 enhanced the inhibitory effects of CBDCA on cell viability and migration ability, and promoted apoptosis in HN-3 cells; whereas the combined treatment of CBDCA and GSH exerted opposite effects. The results of the present study demonstrated that CBDCA promotes the apoptosis of HN-3 cells through accumulation of ROS, which may provide a novel treatment strategy for treating LSCC.

Mechanism of HN‑3 cell apoptosis induced by carboplatin: Combination of mitochondrial pathway associated with Ca2+ and the nucleus pathways

Laryngeal carcinomas have been recognized as a serious health threat worldwide. In the present study, the mechanism of apoptosis in HN-3 cells induced by carboplatin (CBCDA), a widely used anti-cancer drug, was investigated. The pro-apoptotic effect of CBCDA in HN-3 cells was demonstrated to be time- and dose-dependent. Therefore, the stages of apoptosis were investigated in chronological order. The results demonstrated that excessive generation of cytosolic Ca²⁺ in HN-3 cells was initially triggered when cells were exposed to CBCDA, followed by the appearance of mitochondrial depolarization and oxidative stress, leading to the release of apoptosis-inducing factor. At later stages, expression of caspase-8 was increased due to the apoptotic signals originating from CBCDA-induced DNA damage, as well as caspase-9 and poly ADP ribose polymerase (PARP) expression upregulation. Glutathione decreased the available CBDCA concentration, decreased apoptosis and alleviating oxidative stress, thus reducing the actual effective concentration. Mechanistic research may benefit the rational design of more efficient therapeutic strategies as well as development of novel platinum-based agents.