m-THPC-Mediated Photodynamic Therapy (PDT) Does Not Induce Resistance to Chemotherapy, Radiotherapy or PDT on Human Breast Cancer Cells In Vitro

8-Hydroxyquinoline-modified ruthenium(II) polypyridyl complexes for JMJD inhibition and photodynamic antitumor therapy

As an ideal scaffold for metal ion chelation, 8-hydroxyquinoline (8HQ) can chelate different metal ions, such as Fe²⁺, Cu²⁺, Zn²⁺, etc. Here, by integrating 8HQ with a ruthenium(II) polypyridyl moiety, two Ru(II)-8HQ complexes (Ru1 and Ru2), [Ru(N-N)₂L](PF₆)₂ (L = 2-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)quinolin-8-ol; N-N: 2,2'-bipyridine (bpy, in Ru1), 1,10-phenanthroline (phen, in Ru2)) were designed and synthesized. In both complexes, ligand L is an 8HQ derivative designed to chelate the cofactor Fe²⁺ of jumonji C domain-containing demethylase (JMJD). As expected, Ru1 and Ru2 could inhibit the activity of JMJD by chelating the key cofactor Fe²⁺ of JMJD, resulting in the upregulation of histone-methylation levels in human lung cancer (A549) cells, and the upregulation was more pronounced under light conditions. In addition, MTT data showed that Ru1 and Ru2 exhibited lower dark toxicity, and light irradiation could significantly enhance their antitumor activity. The marked photodynamic activities of Ru1 and Ru2 could induce the elevation of reactive oxygen species (ROS), depolarization of mitochondrial membrane potential (MMP), and activation of caspases. These mechanistic studies indicated that Ru1 and Ru2 could induce apoptosis through the combination of JMJD inhibitory and PDT activities, thereby achieving dual antitumor effects.

Mitochondria-Specific Agents for Photodynamic Cancer Therapy: A Key Determinant to Boost the Efficacy

Mitochondria-targeted photodynamic therapy (Mt-PDT), which enables the photogenerated cytotoxic oxygen species with fatal oxidative damage to block mitochondrial functions, has been considered as a promising method to enhance the anticancer effectiveness. Aiming at the challenges of PDT, in the past few decades, numerous mitochondria-targeting molecular agents have been developed to boost the PDT efficacy via directly destroying the mitochondria or activating mitochondria-mediated cell death pathways. Herein, a review for recent advances of Mt-PDT is highlighted including: mitochondrial targeting design principles and strategies, therapeutic performance of mitochondria-targeted agents-mediated PDT as well as the agent-free Mt-PDT. In addition, it puts together the achievements of the combinatory mitochondria-anchoring PDT and other anticancer strategies, demonstrating the advantages provided by Mt-PDT. The existing challenges are discussed and future settlements for the development of mitochondria-specific agents are also forecasted.

Functionalized Eu(III)-based nanoscale metal-organic framework for enhanced targeted anticancer therapy

To improve the cancer targeting and anticancer efficacy, the multifunctional Eu-based metal-organic framework (EuBTC) is post-synthetically modified with a targeting moiety folic acid and a zinc phthalocyanine photosensitizer. In addition, this nanosphere is also applied as a drug delivery system to load the chemical drug doxorubicin. Electron microscopy, powder X-ray diffraction and infrared spectometry demonstrated the formation of these multifunctional nanospheres (DOX). Our nanospheres kept the high singlet oxygen quantum yield of zinc phthalocyanine. Additionally, Cell viability experiments demonstrated the biosafety of EuBTC and the enhanced anticancer effect of DOX@FA-EuBTC-Pc under light irradiation. In short, these well-arranged DOX@FA-Eu-BTC-Pcs exhibit as promising drug delivery systems for enhanced targeted anticancer therapy.

Glycol porphyrin derivatives and temoporfin elicit resistance to photodynamic therapy by different mechanisms

The development of drug resistance is a major problem which often occurs during anticancer chemotherapies. Photodynamic therapy (PDT) has been studied as an alternative treatment modality for drug-resistant tumors, however the question of resistance to PDT and potential cross-resistance with chemotherapy has yet to be fully answered. To investigate the mechanism of resistance to PDT, we developed an in vitro experimental model system in a mouse mammary carcinoma cell line 4T1. We used two ethylene glycol derivatives of tetraphenylporphyrin, and tetraphenylchlorin derivative, temoporfin, as photosensitizers (PS). PDT-resistant clones were obtained by exposure to a set concentration of PS followed by irradiation with increasing light doses. PDT resistance to soluble glycol porphyrins was mediated mainly by increased drug efflux through ABCB1 (P-glycoprotein) as we demonstrated by specific ABCB1 knockdown experiments, which in turn rescued the sensitivity of resistant cells to PDT. In contrast, resistance raised to temoporfin, which is generally more lipophilic than glycol porphyrins, elicited mechanism based on sequestration of the drug to lysosomes. The resistance that is acquired from a particular PS could be overcome by using a different PS, which is not susceptible to the same mechanism(s) of resistance. Elucidation of the underlying mechanisms in various types of resistance might facilitate improvements in PDT treatment design.

The role of cytoskeleton and adhesion proteins in the resistance to photodynamic therapy. Possible therapeutic interventions

It is known that Photodynamic Therapy (PDT) induces changes in the cytoskeleton, the cell shape, and the adhesion properties of tumour cells. In addition, these targets have also been demonstrated to be involved in the development of PDT resistance. The reversal of PDT resistance by manipulating the cell adhesion process to substrata has been out of reach. Even though the existence of cell adhesion-mediated PDT resistance has not been reported so far, it cannot be ruled out. In addition to its impact on the apoptotic response to photodamage, the cytoskeleton alterations are thought to be associated with the processes of metastasis and invasion after PDT. In this review, we will address the impact of photodamage on the microfilament and microtubule cytoskeleton components and its regulators on PDT-treated cells as well as on cell adhesion. We will also summarise the impact of PDT on the surviving and resistant cells and their metastatic potential. Possible strategies aimed at taking advantage of the changes induced by PDT on actin, tubulin and cell adhesion proteins by targeting these molecules will also be discussed.

Effect of FosPeg® mediated photoactivation on P-gp/ABCB1 protein expression in human nasopharyngeal carcinoma cells

Multidrug resistance (MDR) refers to the ability of cancer cells to develop cross resistance to a range of anticancer drugs which are structurally and functionally unrelated. P-glycoprotein (P-gp) is the best studied MDR phenotype in photodynamic therapy (PDT) treated cells. Our pervious study demonstrated that FosPeg® mediated PDT is effective to NPC cell line models. In this in vitro study, the expression of MDR1 gene and its product P-gp in undifferentiated, poorly differentiated and well differentiated human nasopharyngeal carcinoma (NPC) cells were investigated. The influence of P-gp efflux activities on photosensitizer FosPeg® was also examined. Regardless of the differentiation status, PDT tested NPC cell lines all expressed P-gp protein. Results indicated that FosPeg® photoactivation could heighten the expression of MDR1 gene and P-gp transporter protein in a dose dependent manner. Up to 2-fold increase of P-gp protein expression were seen in NPC cells after FosPeg® mediated PDT. Interestingly, our finding demonstrated that FosPeg® mediated PDT efficiency is independent to the MDR1 gene and P-gp protein expression in NPC cells. FosPeg® itself is not the substrate of P-gp transporter protein and no efflux of FosPeg® were observed in NPC cells. Therefore, the PDT efficiency would not be affected even though FosPeg® mediated PDT could induce MDR1 gene and P-gp protein expression in NPC cells. FosPeg® mediated PDT could be a potential therapeutic approach for MDR cancer patients.

mTHPC-mediated photodynamic therapy of early stage oral squamous cell carcinoma: a comparison to surgical treatment

BACKGROUND

mTHPC-mediated photodynamic therapy (PDT) is used for treatment of early head and neck squamous cell carcinoma. This study is a retrospective comparison of PDT with transoral surgery in the treatment of early primary squamous cell carcinoma of the oral cavity/oropharynx.

METHODS

PDT data were retrieved from four study databases; surgical results were retrieved from our institutional database. To select similar primary tumors, infiltration depth was restricted to 5 mm for the surgery group. A total of 126 T1 and 30 T2 tumors were included in the PDT group, and 58 T1 and 33 T2 tumors were included in the surgically treated group.

RESULTS

Complete response rates with PDT and surgery were 86 and 76% for T1, respectively, and for T2 63 and 78%. Lower local disease-free survival for PDT compared to surgery was found. However, when comparing the need for local retreatment, no significant difference for T1 tumors was found, while for T2 tumors surgery resulted in significantly less need for local retreatment. No significant differences in overall survival between surgery and PDT were observed.

CONCLUSIONS

PDT for T1 tumors results in a similar need for retreatment compared to surgery, while for T2 tumors PDT performs worse. Local disease-free survival for surgery is better than for PDT. This may be influenced by the benefit surgery has of having histology available. This allows an early decision on reintervention, while for PDT one has to follow a wait-and-see policy. Future prospective studies should compare efficacy as well as morbidity.

Efficacy and safety of photodynamic therapy with temoporfin in curative treatment of recurrent carcinoma of the oral cavity and oropharynx

Therapeutic options for recurrent carcinoma of the upper aérodigestive tract (UADT) are limited. The prognosis of these tumours remains poor with significant rate of recurrence and a lower median survival time. Photodynamic therapy (PDT) is a relatively new therapeutic alternative which combines the use of a photosensitising agent and light to induce a cytotoxic effect on the tissues. This is a retrospective single-centre study carried out in patients with a recurrence of an oral cavity or oropharyngeal carcinoma or a second appearance of tumour in a previously irradiated area. There were no metastases in lymph nodes or other organs. Laser treatment was carried out 96 h after temoporfin (Foscan(®)) injection. In our series we had 14 cases with a complete response, 1 partial response. Overall survival at 1 year was 72 % and 36 % at 5 years. Disease-specific survival at 1 year was 82 % and 45 % at 5 years. Recurrence-free survival at 1 year was 52 % and 34 % at 5 years. Side effects mainly described are pain in the area of illumination, well controlled. PDT with Foscan(®) gives useful results in terms of survival and improvement in quality of life with few adverse events or severe complications. The fact that it has low toxicity and that treatment sessions can be repeated mean it should be considered in the therapeutic armamentarium for recurrent carcinoma of the UADT.

Temoporfin (Foscan®, 5,10,15,20-tetra(m-hydroxyphenyl)chlorin)--a second-generation photosensitizer

This review traces the development and study of the second-generation photosensitizer 5,10,15,20-tetra(m-hydroxyphenyl)chlorin through to its acceptance and clinical use in modern photodynamic (cancer) therapy. The literature has been covered up to early 2011.

TP53 regulates human AlkB homologue 2 expression in glioma resistance to Photofrin-mediated photodynamic therapy

BACKGROUND

Photodynamic therapy (PDT) is a promising adjuvant therapy in cancer treatment. However, cancers resistant to PDT, mediated through the efflux of photosensitisers by means of P-glycoprotein or ATP-binding cassette transporter proteins, have been reported. The DNA repair has also been suggested to be responsible for PDT resistance, but little is known about the repair pathways and mechanisms involved. Therefore, this study aimed to investigate the possible function of six major DNA repair mechanisms in glioma cells resistant to Photofrin-mediated PDT (Ph-PDT).

METHODS

The U87 glioma cells relatively resistant to Ph-PDT were obtained by recovering the viable cells 3 h after PDT treatment. The mRNA and protein expression levels of DNA repair genes were evaluated by quantitative real-time reverse transcription-polymerase chain reaction and western blotting, respectively. Small-interfering RNA and chromatin-immunoprecipitation assays were used to further examine the relationship between AlkB, an alkylation repair homologue 2 (Escherichia coli) (ALKBH2) and Ph-PDT responsiveness, and transcription factors involved in ALKBH2 transcription.

RESULTS

The ALKBH2 of DNA damage reversal was significantly increased at both mRNA and protein levels from 30 min to 48 h post-treatment with Ph-PDT. Conversely, down-regulating ALKBH2 expression enhances Ph-PDT efficiency. Furthermore, our data clearly show for the first time that tumour protein (TP53) is directly involved by binding to the promoter of ALKBH2 in mediating Ph-PDT resistance.

CONCLUSION

C The DNA damage reversal mechanisms may have important functions in Ph-PDT resistance through the activation of ALKBH2 by TP53.

Photodynamic therapy of early stage oral cavity and oropharynx neoplasms: an outcome analysis of 170 patients

The indications of photodynamic therapy (PDT) of oral cavity and oropharynx neoplasms are not well defined. The main reason is that the success rates are not well established. The current paper analyzes our institutional experience of early stage oral cavity and oropharynx neoplasms (Tis-T2) to identify the success rates for each subgroup according to T stage, primary or non-primary treatment and subsites. In total, 170 patients with 226 lesions are treated with PDT. From these lesions, 95 are primary neoplasms, 131 were non-primaries (recurrences and multiple primaries). The overall response rate is 90.7% with a complete response rate of 70.8%. Subgroup analysis identified oral tongue, floor of mouth sites with more favorable outcome. PDT has more favorable results with certain subsites and with previously untreated lesions. However, PDT can find its place for treating lesions in previously treated areas with acceptable results.

Polymeric micelle nanoparticles for photodynamic treatment of head and neck cancer cells

Objective: To encapsulate 5,10,15,20-tetrakis( meso-hydroxyphenyl)porphyrin (mTHPP), a photosensitizer, into polymeric micelles; characterize the micelles; and test in vitro photodynamic therapy efficacy against human head and neck cancer cells.

Study Design: A nanoparticle design, fabrication, and in vitro testing study.

Setting: Polymer chemistry laboratory.

Subjects and Methods: Micelles encapsulating mTHPP were produced, and micellar size was measured. Ultraviolet visible spectra and fluorescence spectroscopy were used to characterize the mTHPP-loaded micelles. In vitro cell culture using HSC-3 and HN-5 cancer cells was performed to test the photodynamic therapy efficacy of the micelles using confocal microscopy and method of transcriptional and translational (MTT) assay.

Results: mTHPP was encapsulated with high loading efficiency (> 85%) and density (up to 17%) into micelles. Micelle size was 30.6 ± 3.3 nm by transmission electron microscopy and 30.8 ± 0.6 nm by dynamic light scattering. The absorption maximum for each sample was 418 nm, and fluorescent spectroscopy revealed quenching with maximal fluorescence at five percent loading. Significant cytotoxicity was observed with confocal microscopy when HSC-3 cells were treated with 10 percent mTHPP micelles, with 100 percent cytotoxicity within the zone of laser light exposure at 420 nm. Phototoxicity and dark toxicity against HSC-3 and HN-5 cells measured using the MTT assay with five and 10 percent loaded mTHPP micelles demonstrated greater than 90 percent cytotoxicity with photodynamic therapy and less than 10 percent dark toxicity at a micelle concentration of 25 μg/mL for both cell lines.

Conclusion: Micelles were able to encapsulate and solubilize mTHPP at high loading densities with uniform size distribution. These micelles exhibit fluorescence and photodynamic therapy mediated cytotoxicity against head and neck cancer cells in vitro.

Photodynamic diagnosis and therapy and the brain

Photodynamic techniques such as photodynamic diagnosis (PDD), fluorescence-guided tumour resection (FGR) and photodynamic therapy (PDT) are currently undergoing intensive clinical investigations as adjuvant treatment for malignant brain tumours. The following chapter provides an overview on the current clinical data and trials of PDT as well as photosensitizers, technical developments and indications for photodynamic application in neurosurgery. Besides many clinical phase I/II trials for PDT for malignant brain tumours, there are only few controlled clinical trials following tumour resection. Variations in treatment protocols, variation of photosensitizers and light dose make the evaluation scientifically difficult; however there is a clear trend towards prolonging median survival after one single photodynamic treatment as compared to standard therapeutic regimens. According to the meta analysis the median survival after PDT for primary glioblastoma multiforme (WHO grade IV) was 22 months and for recurrent GBM was 9 months as compared to standard conventional treatment, in which it is 15 and 3 months, respectively. Fluorescence-guided resection of the tumour demonstrated significant greater reduction of tumour burden. The combination of PDD/ FGR and intraoperative PDT ("to see and to treat") offers an exciting approach to the treatment of malignant brain tumours. PDT was generally well tolerated and side effects consisted of occasionally increased intracranial pressure and prolonged skin sensitivity against direct sunlight.

Photochemical internalization (PCI) in cancer therapy: from bench towards bedside medicine

PDT in cancer therapy has been reviewed several times recently and many published reports have been showing promising results. The clinical approvals for PDT include curative treatment of early or superficial cancers and palliative treatment of more advanced disease. Still PDT has yet to become a widely used cancer treatment. This may partly be due to limitations in current PDT regimens and partly due to effective alternative treatment modalities. If the specificity and selectivity of PDT could be improved, PDT would probably make substantial progress and comprise an even more competitive alternative in cancer treatment. The PCI technology is based on the same principles as PDT, the activation of a photosensitizer by light and subsequently followed by formation of reactive oxygen species. Unlike PDT, the photosensitizer used in PCI has to be located in the endocytic vesicles of the targeted cells and will, upon activation of light, induce a release of endocytosed therapeutic agents after a photochemically induced rupture of the endocytic vesicles. The endocytosed therapeutic agent will then be released and may reach their intracellular target of action before being degraded in lysosomes. This site-specific drug delivery induced by PCI will take place in addition to the well described cytotoxic, vascular and immunostimulatory effects of PDT. PCI has been shown to facilitate intracellular delivery of a large variety of macromolecules that do not otherwise readily penetrate the plasma membrane, including type I ribosome-inactivating proteins (RIPs), RIP-based immunotoxins, genes and some chemotherapeutic agents. Several animal models have been used for in vivo documentation of the PCI principle and more animal models of clinical relevance have recently been utilized for addressing clinical issues. This review will focus on the possibilities and limitations offered by PCI to overcome some of the challenges recognized in current PDT regimens in cancer treatment.

mTHPC-mediated photodynamic therapy for early oral squamous cell carcinoma

Surgery and radiotherapy are standard treatments for early oral squamous cell carcinoma, both resulting in good tumour control. However, neither of these modalities is without consequent functional or cosmetic impairment, and there are patients in whom both are contraindicated. Furthermore, there is a significant risk of metachronous tumours developing in the oral cavity, and salvage or retreatment with either surgery or radiotherapy poses difficulties. Photodynamic therapy (PDT) offers the potential for improved functional and cosmetic outcomes, while achieving comparable tumour control. We conducted an open-label, multicentre study to assess the efficacy and safety of meta-tetrahydroxyphenylchlorin (mTHPC) in patients with early oral cancer. One hundred twenty-one patients received intravenously administered mTHPC, followed 96 hr later by illumination of the tumour surface with 652 nm laser light. Of these patients, 114 were protocol compliant. A complete tumour response was achieved in 85% of protocol-compliant patients (97 of 114 patients). A complete response was maintained in 85% of responders at 1 year and in 77% at 2 years. One- and 2-year actuarial survival rates were 89% and 75%, respectively. In the opinion of the investigators, tumour clearance was accompanied by excellent cosmetic and functional results, without impact on the patients' performance status. Mild-to-moderate pain at the treatment site, a recognised side effect of PDT in the oral cavity, was reported by 82% of patients but was manageable with appropriate analgesia. Mild-to-moderate skin photosensitivity reactions were reported for 13% of patients. mTHPC offers an effective alternative treatment for early oral squamous cell carcinoma. It is associated with excellent functional and cosmetic results and can be used in conjunction with other standard therapies.

Clinical outcomes of photodynamic therapy for head-and-neck cancer

Head-and-neck cancers not only carry poor prognoses, but also reduced quality of life for the patients. Disease control is often achieved at the expense of substantial functional loss and disfigurement. Photodynamic therapy (PDT) is particularly well suited to the treatment of head-and-neck-tumors because it has little effect on underlying functional structures and has an excellent cosmetic outcome. Studies in the past decades have shown that PDT is of similar efficacy as traditional measures in the treatment of early-stage head-and-neck cancers with an overall response rate of 85%-100% with up to 75% of the complete responses sustained at 2 years after PDT. For advanced head-and-neck cancers, studies were also conducted to evaluate the palliative effects of PDT. Overall, 58%-70% palliative benefit can be observed in these patients. Using interstitial PDT, median survival of the patients with recurrent unresectable head-and-neck cancers can be improved to 14 months (cf. 226 days by using surface illumination PDT). PDT is thus a therapeutic option that may prove a useful addition to the armamentarium of the integrated head and neck oncology team.

Photodynamic therapy of DNA mismatch repair-deficient and -proficient tumour cells

Loss of DNA mismatch repair is a common finding in hereditary nonpolyposis colon cancer as well as in many types of sporadic human tumours. DNA mismatch repair-deficient cells have been reported to be resistant to many chemotherapeutic agents and to radiotherapy, and to have the potential of rapidly acquiring additional mutations leading to tumour progression. Photodynamic therapy is a new treatment modality using light to activate a photosensitiser that preferentially localises in tumour cells. An oxygen dependent photochemical reaction ensues, resulting in selective tumour necrosis. The effect of loss of DNA mismatch repair activity on the sensitivity to photodynamic therapy was tested using pairs of cell lines proficient or deficient in mismatch repair due to loss of either MLH1 or MSH2 protein function. Cells were incubated with the photosensitiser 5,10,15,20-meta-tetra(hydroxyphenyl)chlorin and exposed to laser light at 652 nm with various optical doses ranging from 0-1 J cm(-2). Cell survival was assessed using the clonogenic assay. Loss of MLH1 or MSH2 function was not associated with resistance to photodynamic therapy. MCF-7 cells repeatedly treated with photodynamic therapy expressed parental levels of MLH1, MSH2, MSH6, and PMS2. DNA mismatch repair-deficient and -proficient cells showed similar subcellular distributions of meta-tetra(hydroxyphenyl)chlorin as analysed by laser scanning and fluorescence microscopy. Therefore, repeated exposure of tumour cells to photodynamic therapy does not seem to result in loss of DNA mismatch repair, and loss of mismatch repair, in turn, does not seem to contribute to resistance to photodynamic therapy. Our results suggest recommending photodynamic therapy as a strategy for circumventing resistance due to loss of DNA mismatch repair.

Photodynamic therapy of locoregional breast cancer recurrences using a chlorin-type photosensitizer

Chest wall recurrences are a frequent problem in patients treated by mastectomy for breast cancer. Surgery and ionizing radiation are established treatment modalities in these cases. Photodynamic therapy (PDT) provides an alternative treatment modality using a photosensitizer and laser light to induce selective tumor necrosis. PDT was performed as compassionate use in 7 patients aged 57.6 years (+/-12.6 SD). A total of 89 metastatic skin nodes were treated in 11 PDT sessions. As photosensitizer meta-tetra(hydroxyphenyl)chlorin (m-THPC) was applied intravenously. Patients (n = 3) photosensitized with a drug dose of 0.10 mg/kg bodyweight were irradiated 48 hr after drug application at a lightdose of 5 J/cm(2). Patients (n = 4) were illuminated by an optical dose of 10 J/cm(2) 96 hr after photosensitization with 0.15 mg/kg. Laser light at a wavelength of 652 nm was generated by a diode laser and applied by a front lens light diffuser using a fluence rate of 20--25 mW/cm(2). PDT using m-THPC resulted in complete response in all patients. Response to treatment did not differ when using the 2 different drugdose protocols. Healing time depended mainly on the size of the illumination field but not on the lightdose. Pain score usually raised 1 day after PDT and lasted at higher levels for about 10 days. Healing time usually ranged between 8--10 weeks. Photodynamic technique offers a minimal-invasive, outpatient treatment modality for recurrent breast cancer on the chest wall with few side effects, high patient's satisfaction and with possible repetitive application.

Chronic exposure of human ovarian carcinoma cells to free or HPMA copolymer-bound mesochlorin e6 does not induce P-glycoprotein-mediated multidrug resistance

The acquisition of multidrug resistance in human ovarian carcinoma A2780 cells was investigated after chronic exposure to free mesochlorin e6 monoethylenediamine (Mce6) and N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-bound Mce6 (P(GG)-Mce6). The dose that inhibits growth by 50% (IC50) was determined for free Mce6 (2.09 +/- 0.32 microM) and P(GG)-Mce6 (204.15 +/- 28.97 microM) to utilize similar effective doses of drug. A total of 14 drug exposures were performed over a period of 78 days. Cells were characterized by IC50 dose, MDR1 gene expression and anti-human P-glycoprotein (P-gp) antibody binding after each drug exposure. At the conclusion of the experiment, neither the A2780 cells habitually exposed to free Mce6 or P(GG)-Mce6 were significantly different than the control A2780 cells indicating cells did not acquire a MDR phenotype. The doxorubicin (DOX)-resistant A2780/AD cells served as a positive control.

Cellular uptake, subcellular localization and photodamaging effect of temoporfin (mTHPC) in nasopharyngeal carcinoma cells: comparison with hematoporphyrin derivative

Temoporfin (meta-tetra (hydroxyphenyl)chlorin; mTHPC) potentiated a 100-fold higher cytotoxic effect than hematoporphyrin derivative (HPD) on two nasopharyngeal carcinoma cell lines (HK1 and CNE2) in terms of the overall photodynamic therapy (PDT) dose. The cellular uptake, evaluated by flow cytometry and spectrophotometry demonstrated that mTHPC exhibited higher uptake ability than HPD. Confocal laser scanning microscopy detection for both the sensitizer and mitochondria probe on the same cell images revealed that both drugs accumulated diffusely in the cytoplasm and that mitochrondria is a target organelle. Photo-activation ruptured the mitochrondria, with more pronounced mitochondrial damage being observed in mTHPC-PDT course. This correlated well with the cell photokilling efficiency of mTHPC.

Photodynamic therapy for the hypercalcemic type of the small cell carcinoma of the ovary in a mouse xenograft model

OBJECTIVE

The hypercalcemic type of the small cell carcinoma of the ovary (HTSCCO) is a rapidly fatal ovarian tumor in young women. Photodynamic therapy (PDT) induces selective necrosis to malignant tissues. The aim of this study was to determine the sensitivity of the HTSCCO to PDT in a mouse xenograft model.

METHODS

Tumors were obtained from a patient with a HTSCCO and were transplanted into nude mice. Following photosensitization with m-THPC, either superficial or interstitial laser light was administered to the tumors. Necroses were measured by morphometry. Serum calcium levels were determined prior to and after PDT.

RESULTS

Superficial irradiation of m-THPC sensitized tumors showed over three times more necrosis than control tumors (P = 0.037). Interstitially irradiated tumors showed over seven times more necrosis than control tumors (P = 0.0012). All animals showed a highly significant hypercalcemia prior to PDT (P < 0.0001). PDT induced a significant decrease in serum calcium levels (P = 0.0297).

CONCLUSION

This study suggests that PDT may be of therapeutic value for the HTSCCO.