Preclinical validation of talaporfin sodium-mediated photodynamic therapy for esophageal squamous cell carcinoma

Transvascular delivery of talaporfin sodium to subcutaneous tumors in mice by nanosecond pulsed laser-induced photomechanical waves

BACKGROUND

We previously developed a site-specific transvascular drug delivery system (DDS) based on photomechanical waves (PMWs) or laser-induced stress/shock waves (LISWs). In this study, we investigated the validity of this method to deliver a clinical photosensitizer, talaporfin sodium (TS), to subcutaneous tumors in mice and to enhance the efficacy of photodynamic therapy (PDT).

METHODS

TS solution (2.5 mg/kg) was intravenously injected into mice. Immediately thereafter, PMWs were applied to the tumor by irradiating a laser target with a Q-switched ruby laser pulse (0.8 J/cm2). Five hours after TS administration, some tumors were excised to evaluate the depth distribution of the delivered TS under a fluorescence microscope. Other tumors were subjected to PDT by irradiating the tissues with a 665 nm continuous-wave laser diode (75 mW/cm2, 667 s) at this timepoint. The effects of PDT were evaluated on the basis of the two primary therapeutic mechanisms of TS-mediated PDT: i) damage to tumor cells and ii) damage to endothelial cells of tumor vessels, i.e., the vascular shutdown effect on tumors.

RESULTS

PMW application significantly increased the accumulation of TS in the tumor parenchyma but not in the tumor vessel walls; the endothelial cell junctions of tumor vessels should be the route of TS delivery enhanced by PMWs. Thus, as a result of PMW application followed by PDT, while the vascular shutdown effect on the tumors was not enhanced, direct damage to the tumor cells was increased, resulting in significant tumor growth retardation without body weight loss for 7 days after treatment.

In Vitro Comparative Study of Near-Infrared Photoimmunotherapy and Photodynamic Therapy

Near-infrared photoimmunotherapy (NIR-PIT) is a new phototherapy that utilizes a monoclonal antibody (mAb) against cancer antigens and a phthalocyanine dye, IRDye700DX (IR700) conjugate (mAb-IR700). Photodynamic therapy (PDT) is a combination therapy that utilizes photoreactive agents and light irradiation as well as NIR-PIT. In the present study, we compared these therapies in vitro. The characterization of cellular binding/uptake specificity and cytotoxicity were examined using two mAb-IR700 forms and a conventional PDT agent, talaporfin sodium, in three cell lines. As designed, mAb-IR700 had high molecular selectivity and visualized target molecule-positive cells at the lowest concentration examined. NIR-PIT induced necrosis and damage-associated molecular patterns (DAMPs), a surrogate maker of immunogenic cell death. In contrast, talaporfin sodium was taken up by cells regardless of cell type, and its uptake was enhanced in a concentration-dependent manner. PDT induced cell death, with the pattern of cell death shifting from apoptosis to necrosis depending on the concentration of the photosensitizer. Induction of DAMPs was observed at the highest concentration, but their sensitivity differed among cell lines. Overall, our data suggest that molecule-specific NIR-PIT may have potential advantages compared with PDT in terms of the efficiency of tumor visualization and induction of DAMPs.

Current Advances in Photoactive Agents for Cancer Imaging and Therapy

Photoactive agents are promising complements for both early diagnosis and targeted treatment of cancer. The dual combination of diagnostics and therapeutics is known as theranostics. Photoactive theranostic agents are activated by a specific wavelength of light and emit another wavelength, which can be detected for imaging tumors, used to generate reactive oxygen species for ablating tumors, or both. Photodynamic therapy (PDT) combines photosensitizer (PS) accumulation and site-directed light irradiation for simultaneous imaging diagnostics and spatially targeted therapy. Although utilized since the early 1900s, advances in the fields of cancer biology, materials science, and nanomedicine have expanded photoactive agents to modern medical treatments. In this review we summarize the origins of PDT and the subsequent generations of PSs and analyze seminal research contributions that have provided insight into rational PS design, such as photophysics, modes of cell death, tumor-targeting mechanisms, and light dosing regimens. We highlight optimizable parameters that, with further exploration, can expand clinical applications of photoactive agents to revolutionize cancer diagnostics and treatment.

Combination of talaporfin photodynamic therapy and Poly (ADP-Ribose) polymerase (PARP) inhibitor in gastric cancer

Photodynamic therapy (PDT) utilizes photochemical reactions induced by a photosensitizer and light in the target tissue and is used to treat various cancers. There is a high degree of anticipation of success regarding the application of PDT with talaporfin (photosensitizer) for gastric cancer. Olaparib is an oral inhibitor of Poly (ADP-Ribose) polymerase (PARP) and has demonstrated optimal efficacy and clinical activity in trials. Therefore, the aim of the present study was to investigate the efficacy of talaporfin PDT combined with olaparib for gastric cancer. MKN45, a gastric cancer cell line, was incubated with talaporfin, followed by irradiation, in the presence/absence of olaparib. Talaporfin PDT and olaparib exhibited excellent synergistic action in a concentration-dependent manner. PARP-DNA complexes were characterized based on bound chromatin using Western blot analyses. The combination of talaporfin PDT and olaparib enhanced PARP1 accumulation (the entrapment of PARP1-DNA complexes) in bound chromatin. The combination of talaporfin PDT and olaparib induced DNA double-strand breaks, which was confirmed by evaluating phosphorylated histone H2AX. Xenograft tumor mouse models were established, and antitumor effects were analyzed. In vivo, tumor growth was significantly suppressed following PDT with talaporfin and olaparib. Our results demonstrated that olaparib enhances the efficacy of talaporfin PDT by inducing the formation of PARP-DNA complexes. Therefore, our results suggest that the combination of talaporfin PDT and olaparib is a potential antitumor therapy for gastric cancer.

Synthetic Lethality with Trifluridine/Tipiracil and Checkpoint Kinase 1 Inhibitor for Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is a disease characterized by a high mutation rate of the TP53 gene, which plays pivotal roles in the DNA damage response (DDR) and is regulated by checkpoint kinase (CHK) 2. CHK1 is another key DDR-related protein, and its selective inhibition is suggested to be particularly sensitive to TP53-mutated cancers, because a loss of both pathways (CHK1 and/or CHK2-p53) is lethal due to the serious impairment of DDR. Such a therapeutic strategy is termed synthetic lethality. Here, we propose a novel therapeutic strategy based on synthetic lethality combining trifluridine/tipiracil and prexasertib (CHK1 inhibitor) as a treatment for ESCC. Trifluridine is a key component of the antitumor drug combination with trifluridine/tipiracil (an inhibitor of trifluridine degradation), also known as TAS-102. In this study, we demonstrate that trifluridine increases CHK1 phosphorylation in ESCC cells combined with a reduction of the S-phase ratio as well as the induction of ssDNA damage. Because CHK1 phosphorylation is considered to be induced as DDR for trifluridine-mediated DNA damage, we examined the effects of CHK1 inhibition on trifluridine treatment. Consequently, CHK1 inhibition by short hairpin RNA or treatment with the CHK1 inhibitor, prexasertib, markedly enhanced trifluridine-mediated DNA damage, represented by an increase of γH2AX expression. Moreover, the combination of trifluridine/tipiracil and CHK1 inhibition significantly suppressed tumor growth of ESCC-derived xenograft tumors. Furthermore, the combination of trifluridine and prexasertib enhanced radiosensitivity both in vitro and in vivo Thus, the combination of trifluridine/tipiracil and a CHK1 inhibitor exhibits effective antitumor effects, suggesting a novel therapeutic strategy for ESCC.

Non-aggregated lipophilic water-soluble tin porphyrins as photosensitizers for photodynamic therapy and photodynamic antimicrobial chemotherapy

Readily-synthesized water-soluble Sn(iv) tetrapyridylporphyrin dyes have been prepared which exhibit enhanced properties for use as photosensitizer dyes in biomedical applications.

DWI for Monitoring the Acute Response of Malignant Gliomas to Photodynamic Therapy

BACKGROUND AND PURPOSE

Photodynamic therapy is a novel treatment that provides effective local control, but little is known about photodynamic therapy-induced changes on MR imaging. The aim of this study was to assess the utility of DWI and ADC in monitoring the response of malignant gliomas to photodynamic therapy.

MATERIALS AND METHODS

Time-dependent changes in DWI and ADC values after photodynamic therapy were analyzed in a group that received photodynamic therapy in comparison with a group that did not.

RESULTS

Twenty-four patients were enrolled (photodynamic therapy, n = 14; non-photodynamic therapy, n = 10). In all patients who received photodynamic therapy, linear high signals on DWI in the irradiated area were detected adjacent to the resection cavity and were 5-7 mm in depth from 1 day posttreatment and disappeared in about 30 days without any neurologic deterioration. The non-photodynamic therapy group did not show this change. The photodynamic therapy group had significantly lower ADC values from 1 day posttreatment (P < .001), which increased steadily and disappeared by 30 days. There was no decline or time-dependent change in ADC values in the non-photodynamic therapy group.

CONCLUSIONS

The acute response of malignant gliomas to photodynamic therapy was detected as linear high signals on DWI and as a decrease in ADC values. These findings were asymptomatic and transient. Although the photodynamic therapy-induced acute response on MR imaging disappeared after approximately 30 days, it may be helpful for confirming the photodynamic therapy-irradiated area.

Protoporphyrin IX-loaded laminarin nanoparticles for anticancer treatment, their cellular behavior, ROS detection, and animal studies

Laminarin conjugate-based nano-scaled particles were in this study proposed as a delivery system for protoporphyrin IX (Pp IX) in photodynamic therapy (PDT) of human breast cancer cells (MCF-7). Hematin-Laminarin-Dithiodipropionic Acid-MGK, named as HLDM, was an amphiphilic carrier material with dual pH/redox sensitive that could be used to load hydrophobic drug to improve their solubility and enhance biocompatibility. Therefore, we combined photosensitizer (Pp IX) with HLDM to fabricate a novel nano-micelles, herein called Pp IX-loaded HLDM micelles. The Pp IX-loaded HLDM micelles were 149.3 ± 35 nm sized in neutral water. Phototoxicity, in vitro PDT effect, and dual sensibility to pH and redox microenvironment of Pp IX-loaded HLDM micelles were examined at different concentrations by using MCF-7 human breast cancer cells. The experiments on phototoxicity and reactive oxygen species (ROS) production proved that the micelles could produce PDT to kill the cancer cells with a certain wavelength light. The apoptosis experiment indicated that the micelles could cause nuclear damage. In vivo PDT effect of the micelles was studied by constructing the tumor-bearing nude mouse model of MCF-7 cells. In vivo studies showed that the Pp IX-loaded HLDM micelles could induce remarkable anti-tumor effect. A promising laminarin-based nanomedicine platform acts as a new drug delivery system to enhance the uptake, accumulation, and PDT efficacy of Pp IX in vitro and in vivo.

Effects of palmatine hydrochloride mediated photodynamic therapy on oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a common malignant tumor, accounting for about 7% of all malignant tumors. Palmatine hydrochloride (PaH) is the alkaloid constituent of Fibraurea tinctoria Lour. The present study aims to investigate the antitumor effect of photodynamic therapy (PDT) with PaH (PaH-PDT) on human OSCC cell lines both in vitro and in vivo. The results indicate that PaH-PDT exhibited a potent phototoxic effect in cell proliferation and produced cell apoptosis. PaH-PDT increased the percentage of cells in the G0/G1 phase and decreased the CDK2 and Cyclin E1 protein level. In addition, PaH-PDT markedly increased the generation of intracellular ROS, which can be suppressed using the ROS scavenger N-acetylcysteine (NAC). Furthermore, PaH-PDT increased the expression of p53 protein in vitro and in vivo. In vivo experiments revealed that the PaH-PDT resulted in an effective inhibition of tumor growth and prolonged the survival time of tumor-bearing mice. Moreover, no obvious signs of side effects or a drop in body weight was observed. These results suggested that PaH was a promising sensitizer that can be combined with light to produce significant anti-tumor effects in oral squamous cell carcinoma via enhanced ROS production and up-regulated expression of p53.

Photoimmunotherapy for cancer-associated fibroblasts targeting fibroblast activation protein in human esophageal squamous cell carcinoma

Cancer-associated fibroblasts (CAFs) are strongly implicated in tumor progression, including in the processes of tumorigenesis, invasion, and metastasis. The targeting of CAFs using various therapeutic approaches is a novel treatment strategy; however, the efficacy of such therapies remains limited. Recently, near-infrared photoimmunotherapy (NIR-PIT), which is a novel targeted therapy employing a cell-specific mAb conjugated to a photosensitizer, has been introduced as a new type of phototherapy. In this study, we have developed a novel NIR-PIT technique to target CAFs, by focusing on fibroblast activation protein (FAP), and we evaluate the treatment efficacy in vitro and in vivo. Esophageal carcinoma cells exhibited enhanced activation of fibroblasts, with FAP over-expressed in the cytoplasm and on the cell surface. FAP-IR700-mediated PIT showed induced rapid cell death specifically for those cells in vitro and in vivo, without adverse effects. This novel therapy for CAFs, designed as local control phototherapy, was safe and showed a promising inhibitory effect on FAP⁺ CAFs. PIT targeting CAFs via the specific marker FAP may be a therapeutic option for CAFs in the tumor microenvironment in the future.

Three-Dimensional Organoids Reveal Therapy Resistance of Esophageal and Oropharyngeal Squamous Cell Carcinoma Cells

BACKGROUND & AIMS

Oropharyngeal and esophageal squamous cell carcinomas, especially the latter, are a lethal disease, featuring intratumoral cancer cell heterogeneity and therapy resistance. To facilitate cancer therapy in personalized medicine, three-dimensional (3D) organoids may be useful for functional characterization of cancer cells ex vivo. We investigated the feasibility and the utility of patient-derived 3D organoids of esophageal and oropharyngeal squamous cell carcinomas.

METHODS

We generated 3D organoids from paired biopsies representing tumors and adjacent normal mucosa from therapy-naïve patients and cell lines. We evaluated growth and structures of 3D organoids treated with 5-fluorouracil ex vivo.

RESULTS

Tumor-derived 3D organoids were grown successfully from 15 out of 21 patients (71.4%) and passaged with recapitulation of the histopathology of the original tumors. Successful formation of tumor-derived 3D organoids was associated significantly with poor response to presurgical neoadjuvant chemotherapy or chemoradiation therapy in informative patients (P = 0.0357, progressive and stable diseases, n = 10 vs. partial response, n = 6). The 3D organoid formation capability and 5-fluorouracil resistance were accounted for by cancer cells with high CD44 expression and autophagy, respectively. Such cancer cells were found to be enriched in patient-derived 3D organoids surviving 5-fluorouracil treatment.

CONCLUSIONS

The single cell-based 3D organoid system may serve as a highly efficient platform to explore cancer therapeutics and therapy resistance mechanisms in conjunction with morphological and functional assays with implications for translation in personalized medicine.

NFkB hyperactivation causes invasion of esophageal squamous cell carcinoma with EGFR overexpression and p120-catenin down-regulation

Four out of five patients diagnosed with esophageal squamous cell carcinoma (ESCC) will die within five years. This is primarily a result of the aggressive invasive potential of the disease. Our research is focused on the interplay between tumor suppressors and oncogenes in the invasive process. Specifically, EGFR and p120-catenin (p120ctn) are commonly dysregulated genes that are indicative of poor prognosis in ESCC. In a previous study we demonstrated that in our 3D organotypic culture model, only when EGFR overexpression is combined with p120ctn inactivation do the cells transform and invade – as opposed to either event alone. The purpose of this present study was to identify the components of the molecular pathways downstream of p120ctn and EGFR that lead to invasion. Using both human esophageal keratinocytes and human ESCC cells, we have identified NFkB as a central regulator of the invasive process downstream of p120ctn down-regulation and EGFR overexpression. Interestingly, we found that NFkB is hyperactivated in cells with EGFR overexpression and p120ctn inactivation than with either EGFR or p120ctn alone. Inhibition of this NFkB hyperactivation results in complete loss of invasion, suggesting that NFkB signaling is necessary for invasion in this aggressive cell type. Furthermore, we have identified RhoA and Rho-kinase as upstream regulators of NFkB in this process. We believe the cooperation of p120ctn down-regulation and EGFR overexpression is not only important in the aggressive mechanisms of ESCC but could be broadly applicable to many other cancer types in which p120ctn and EGFR are involved.

A multicenter phase II study of salvage photodynamic therapy using talaporfin sodium (ME2906) and a diode laser (PNL6405EPG) for local failure after chemoradiotherapy or radiotherapy for esophageal cancer

Photodynamic therapy (PDT) showed promising efficacy for local failure after chemoradiotherapy (CRT) for esophageal cancer. However, PDT required long sun shade period. This study aimed to evaluate the safety and efficacy of PDT using second generation photosensitizer, talaporfin sodium for local failure after CRT. This was the multi-institutional non-randomized phase II study. Patients with histologically proven local failure limited within the muscularis propria after 50Gy or more radiotherapy (RT) for esophageal cancer were eligible. We set the primary endpoint as local complete response (L-CR) per patients. And, secondary endpoints were confirmed L-CR, local progression free survival (L-PFS), progression free survival (PFS), overall survival (OS), L-CR per lesions (Lesion L-CR), and confirmed Lesion L-CR. The PDT procedure commenced with intravenous administration of a 40 mg/m² dose of talaporfin sodium followed by diode laser irradiation at a 664 nm wavelength. 26 eligible patients were enrolled and all were treated with PDT. Twenty three patients with 25 lesions were assessed L-CR after PDT; the L-CR rate per patients was 88.5% (95% CI: 69.8%-97.6%). No skin phototoxicity was observed, and no grade 3 or worse non-hematological toxicities related to PDT were observed. PDT using talaporfin sodium and a diode laser is a safe and curative salvage treatment for local failure after CRT or RT for patients with esophageal cancer.

Distinct effects of EGFR inhibitors on epithelial- and mesenchymal-like esophageal squamous cell carcinoma cells

Background

Epidermal growth factor receptor (EGFR) plays a pivotal role in the pathophysiology of esophageal squamous cell carcinoma (ESCC). However, the clinical effects of EGFR inhibitors on ESCC are controversial. This study sought to identify the factors determining the therapeutic efficacy of EGFR inhibitors in ESCC cells.

Methods

Immortalized-human esophageal epithelial cells (EPC2-hTERT), transformed-human esophageal epithelial cells (T-Epi and T-Mes), and ESCC cells (TE-1, TE-5, TE-8, TE-11, TE-11R, and HCE4) were treated with the EGFR inhibitors erlotinib or cetuximab. Inhibitory effects on cell growth were assessed by cell counting or cell-cycle analysis. The expression levels of genes and proteins such as involucrin and cytokeratin13 (a squamous differentiation marker), E-cadherin, and vimentin were evaluated by real-time polymerase chain reaction or western blotting. To examine whether mesenchymal phenotype influenced the effects of EGFR inhibitors, we treated T-Epi cells with TGF-β1 to establish a mesenchymal phenotype (mesenchymal T-Epi cells). We then compared the effects of EGFR inhibitors on parental T-Epi cells and mesenchymal T-Epi cells. TE-8 (mesenchymal-like ESCC cells)- or TE-11R (epithelial-like ESCC cells)-derived xenograft tumors in mice were treated with cetuximab, and the antitumor effects of EGFR inhibitors were evaluated.

Results

Cells were classified as epithelial-like or mesenchymal-like phenotypes, determined by the expression levels of E-cadherin and vimentin. Both erlotinib and cetuximab reduced cell growth and the ratio of cells in cell-cycle S phase in epithelial-like but not mesenchymal-like cells. Additionally, EGFR inhibitors induced squamous cell differentiation (defined as increased expression of involucrin and cytokeratin13) in epithelial-like but not mesenchymal-like cells. We found that EGFR inhibitors did not suppress the phosphorylation of EGFR in mesenchymal-like cells, while EGFR dephosphorylation was observed after treatment with EGFR inhibitors in epithelial-like cells. Furthermore, mesenchymal T-Epi cells showed resistance to EGFR inhibitors by circumventing the dephosphorylation of EGFR signaling. Cetuximab consistently showed antitumor effects, and increased involucrin expression in TE-11R (epithelial-like)-derived xenograft tumors but not TE-8 (mesenchymal-like)-derived xenograft tumors.

Conclusions

The factor determining the therapeutic effects of EGFR inhibitors in ESCC cells is the phenotype representing the epithelial-like or mesenchymal-like cells. Mesenchymal-like ESCC cells are resistant to EGFR inhibitors because EGFR signaling is not blocked. EGFR inhibitors show antitumor effects on epithelial-like ESCC cells accompanied by promotion of squamous cell differentiation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-017-0572-7) contains supplementary material, which is available to authorized users.

Oxidative stress mediated by nitrogen at elevated pressure inhibits non-small cell lung cancer growth

Purpose/Aim: High pressures of gases such as nitrogen enhance production of singlet oxygen. Therefore, we hypothesized that growth of non-small cell lung cancer (NSCLC) A549 cells and a human-derived NSCLC explant could be inhibited by an oxidative stress mechanism using high-pressure nitrogen.

MATERIALS AND METHODS

Growth of human NSCLC explants and A549 cells in Matrigel were assessed after implantation into nude mice who were exposed to elevated pressures.

RESULTS

Subcutaneous implant growth of NSCLC in nude mice was inhibited by a daily 78-minute protocol using nitrogen/oxygen breathing mixture such that at the maximum pressure of 2.78 atmospheres over ambient, mice breathed oxygen at normal atmospheric pressure. In vivo growth inhibition of A549 cells by high-pressure nitrogen could be abrogated in subcutaneous Matrigel implants when supplemented with 10-mM N-acetylcysteine as an antioxidant. Ex vivo A549 cell exposures exhibited elevated singlet oxygen production, and reactive oxygen species were produced for up to 4 hours after short-term high-pressure nitrogen exposure.

CONCLUSIONS

This pilot study demonstrates that elevated normoxic nitrogen pressure can exacerbate oxidative stress in NSCLC to inhibit growth.

Maltotriose Conjugation to a Chlorin Derivative Enhances the Antitumor Effects of Photodynamic Therapy in Peritoneal Dissemination of Pancreatic Cancer

Peritoneal dissemination is a major clinical issue associated with dismal prognosis and poor quality of life for patients with pancreatic cancer; however, no effective treatment strategies have been established. Herein, we evaluated the effects of photodynamic therapy (PDT) with maltotriose-conjugated chlorin (Mal₃-chlorin) in culture and in a peritoneal disseminated mice model of pancreatic cancer. The Mal₃-chlorin was prepared as a water-soluble chlorin derivative conjugated with four Mal₃ molecules to improve cancer selectivity. In vitro, Mal₃-chlorin showed superior uptake into pancreatic cancer cells compared with talaporfin, which is clinically used. Moreover, the strong cytotoxic effects of PDT with Mal₃-chlorin occurred via apoptosis and reactive oxygen species generation, whereas Mal₃-chlorin alone did not cause any cytotoxicity in pancreatic cancer cells. Notably, using a peritoneal disseminated mice model, we demonstrated that Mal₃-chlorin accumulated in xenograft tumors and suppressed both tumor growth and ascites formation with PDT. Furthermore, PDT with Mal₃-chlorin induced robust apoptosis in peritoneal disseminated tumors, as indicated by immunohistochemistry. Taken together, these findings implicate Mal₃-chlorin as a potential next-generation photosensitizer for PDT and the basis of a new strategy for managing peritoneal dissemination of pancreatic cancer. Mol Cancer Ther; 16(6); 1124-32. ©2017 AACR.

Novel EGFR-targeted strategy with hybrid peptide against oesophageal squamous cell carcinoma

Epidermal growth factor receptor (EGFR) is a key molecule in the pathophysiology of oesophageal squamous cell carcinoma (OSCC). However, EGFR-targeted agents such as anti-EGFR antibody or tyrosine kinase inhibitors for OSCC have not demonstrated any clinical benefits. Recently, a novel chemotherapeutic agent, EGFR(2R)-lytic hybrid peptide, a composite of EGFR-binding peptide and lytic peptide fragments, has been shown to exhibit a potent anti-tumour effect against cancers that express high EGFR levels. In this study, we investigated the validity of employing EGFR(2R)-lytic hybrid peptide against OSCC cells both in vitro and in vivo. Additionally, the toxicity of this peptide was assessed in mice. We found high EGFR expression levels on the cell surface of OSCC cells, and the EGFR-binding peptide fragment showed high affinity for OSCC cells. A potent cytotoxic effect was induced within 30 minutes by the exposure of OSCC cells to EGFR(2R)-lytic hybrid peptide. Furthermore, EGFR(2R)-lytic hybrid peptide markedly suppressed the tumour growth of OSCC cells in a xenograft model. Moreover, it did not cause any identifiable adverse effects in mice. Taken together, EGFR(2R)-lytic hybrid peptide was shown to be a valid therapeutic agent against OSCC, providing a crucial rationale regarding novel EGFR-targeted therapies against OSCC.

DNA photo-cleaving agents in the far-red to near-infrared range – a review

Ideal photonucleases for clinical applications cleave DNA upon activation with deeply penetrating far-red to near-infrared light.

Apoptotic effects of Photofrin-Diomed 630-PDT on SHEEC human esophageal squamous cancer cells

Photodynamic therapy (PDT) using photofrin-II is a clinically effective treatment for both non-neoplastic and neoplastic diseases. Herein, we performed an in vitro experiment to study the anti-tumor effect and mechanisms of photofrin-II mediated PDT for esophageal squamous cell carcinoma (ESCC) cell line, SHEEC. In this study, human ESCC cell line SHEEC and parental normal cell line SHEE were used. The anti-tumor effect of PDT was determined by evaluating cell viability using CCK-8 assay, apoptosis and generation of reactive oxygen species (ROS). PDT induced significant apoptosis in SHEEC and SHEE cells in a time- and photofrin-II dose-dependent manner. Furthermore, PDT treatment induced significant death of SHEEC, instead of SHEE cells. The apoptotic outcome was accompanied by concurrent generation of ROS. In summary, PDT shed light on therapy of ESCC, functioning as a useful tool for ESCC clinical treatment, providing a better understanding of Photofrin-Diomed 630-PDT in SHEEC cells.

Novel 5-fluorouracil-resistant human esophageal squamous cell carcinoma cells with dihydropyrimidine dehydrogenase overexpression

5-Fluorouracil (5-FU) is a key drug for the treatment of esophageal squamous cell carcinoma (ESCC); however, resistance to it remains a critical limitation to its clinical use. To clarify the mechanisms of 5-FU resistance of ESCC, we originally established 5-FU-resistant ESCC cells, TE-5R, by step-wise treatment with continuously increasing concentrations of 5-FU. The half maximal inhibitory concentration of 5-FU showed that TE-5R cells were 15.6-fold more resistant to 5-FU in comparison with parental TE-5 cells. TE-5R cells showed regional copy number amplification of chromosome 1p including the DPYD gene, as well as high mRNA and protein expressions of dihydropyrimidine dehydrogenase (DPD), an enzyme involved in 5-FU degradation. 5-FU treatment resulted in a significant decrease of the intracellular 5-FU concentration and increase of the concentration of α-fluoro-ureidopropionic acid (FUPA), a metabolite of 5-FU, in TE-5R compared with TE-5 cells in vitro. Conversely, gimeracil, a DPD inhibitor, markedly increased the intracellular 5-FU concentration, decreased the intracellular FUPA concentration, and attenuated 5-FU resistance of TE-5R cells. These results indicate that 5-FU resistance of TE-5R cells is due to the rapid degradation of 5-FU by DPD overexpression. The investigation of 5-FU-resistant ESCC with DPYD gene copy number amplification and consequent DPD overexpression may generate novel biological evidence to explore strategies against ESCC with 5-FU resistance.

Fluorescence characteristics and lifetime images of photosensitizers of talaporfin sodium and sodium pheophorbide a in normal and cancer cells

Fluorescence spectra and fluorescence lifetime images of talaporfin sodium and sodium-pheophorbide a, which can be regarded as photosensitizers for photodynamic therapy, were measured in normal and cancer cells. The reduction of the fluorescence intensity by photoirradiation was observed for both photosensitizers in both cells, but the quenching rate was much faster in cancer cells than in normal cells. These results are explained in terms of the excessive generation of reactive oxygen species via photoexcitation of these photosensitizers in cancer cells. The fluorescence lifetimes of both photosensitizers in cancer cells are different from those in normal cells, which originates from the different intracellular environments around the photosensitizers between normal and cancer cells.