Differential photosensitivity in wild-type and mutant p53 human colon carcinoma cell lines

Ruthenium(II)-Arene Curcuminoid Complexes as Photosensitizer Agents for Antineoplastic and Antimicrobial Photodynamic Therapy: In Vitro and In Vivo Insights

Photodynamic therapy (PDT) is an anticancer/antibacterial strategy in which photosensitizers (PSs), light, and molecular oxygen generate reactive oxygen species and induce cell death. PDT presents greater selectivity towards tumor cells than conventional chemotherapy; however, PSs have limitations that have prompted the search for new molecules featuring more favorable chemical-physical characteristics. Curcumin and its derivatives have been used in PDT. However, low water solubility, rapid metabolism, interference with other drugs, and low stability limit curcumin use. Chemical modifications have been proposed to improve curcumin activity, and metal-based PSs, especially ruthenium(II) complexes, have attracted considerable attention. This study aimed to characterize six Ru(II)-arene curcuminoids for anticancer and/or antibacterial PDT. The hydrophilicity, photodegradation rates, and singlet oxygen generation of the compounds were evaluated. The photodynamic effects on human colorectal cancer cell lines were also assessed, along with the ability of the compounds to induce ROS production, apoptotic, necrotic, and/or autophagic cell death. Overall, our encouraging results indicate that the Ru(II)-arene curcuminoid derivatives are worthy of further investigation and could represent an interesting option for cancer PDT. Additionally, the lack of significant in vivo toxicity on the larvae of Galleria mellonella is an important finding. Finally, the photoantimicrobial activity of HCurc I against Gram-positive bacteria is indeed promising.

The miR-34a/WNT7B modulates the sensitivity of cholangiocarcinoma cells to p53-mediated photodynamic therapy toxicity

Photodynamic therapy (PDT) provides apparent survival benefits for unresectable cholangiocarcinoma patients. the insufficient sensitivity of cancer cell to PDT treatment limits the clinical application. In this study, according to the GEO datasets, WNT7B expression was decreased by PDT treatment in cholangiocarcinoma samples. In cholangiocarcinoma cells, PDT treatment inhibited Wnt signaling, suppressed cell viability, and enhanced cell apoptosis. Within cholangiocarcinoma cells, PDT treatment induced p53 and miR-34a-5p expression. Under PDT treatment, p53 knockdown downregulated miR-34a-5p expression, whereas the inhibition effect of p53 knockdown on miR-34a-5p could be partially attenuated by agomir-34a-5p. p53 knockdown enhanced cell viability and suppressed cell apoptosis, whereas miR-34a-5p overexpression exerted opposite effects; miR-34a-5p overexpression partially attenuated p53 knockdown effects on PDT-treated cholangiocarcinoma cells. miR-34a-5p directly targeted WNT7B and inhibited WNT7B expression. Under PDT treatment, WNT7B knockdown inhibited the Wnt signaling and cell viability, and promoted cell apoptosis, while miR-34a-5p suppression showed the opposite trends; WNT7B knockdown partially attenuated miR-34a-5p inhibition effects on PDT-treated cholangiocarcinoma cells. In conclusion, PDT treatment induces p53-induced miR-34a transactivation to inhibit cholangiocarcinoma cell proliferation; the miR-34a-5p/WNT7B axis and Wnt signaling are involved.

ERO1α mediates endoplasmic reticulum stress-induced apoptosis via microRNA-101/EZH2 axis in colon cancer RKO and HT-29 cells

Although colon cancer is a leading and typical gastrointestinal tumor, there is little published data on the underlying molecular mechanisms of endoplasmic reticulum (ER) stress. Here, we investigated the role of ERO1α and its impact on microRNA (miR)-101 expression and ER stress in colon cancer cells. Cell ER stress was established by treating RKO or HT-29 cells with 1 μM thapsigargin (THG). Cell biological behaviors were detected using CCK-8, bromodeoxyuridine assay, flow cytometry and western blot. We also investigated the expression of ERO1α and miR-101 after THG treatment using RT-qPCR. Moreover, effects of ERO1α and miR-101 on ER stress of colon cancer cells were detected. Additionally, miR-101 impact on EZH2 expression and relevance of this regulation was confirmed by RT-qPCR and luciferase reporter. The regulation of miR-101/EZH2 axis and Wnt/β-catenin pathway in ER stress were investigated. Our results demonstrated that THG induced ER stress in colon cancer cells. Silencing ERO1α further promoted ER stress-induced cell apoptosis. ERO1α knockdown up-regulated miR-101 expression and promoted colon cancer cell apoptosis via regulating miR-101. Surprisingly, miR-101 negatively regulated EZH2 expression via miRNA-mRNA targeting. Moreover, ER stress promoted colon cancer cell apoptosis via regulating miR-101/EZH2 axis. Wnt/β-catenin pathway was also involved in the regulation of ERO1α/miR-101/EZH2 in ER stress of colon cancer cells. These findings illustrated that silencing ERO1α regulated ER stress-induced apoptosis via miR-101/EZH2 axis in RKO and HT-29 cells.

New BODIPYs for photodynamic therapy (PDT): Synthesis and activity on human cancer cell lines

A new class of compounds based on the 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene core, known as BODIPYs, has attracted significant attention as photosensitizers suitable for application in photodynamic therapy (PDT), which is a minimally invasive procedure to treat cancer. In PDT the combination of a photosensitizer (PS), light, and oxygen leads to a series of photochemical reactions generating reactive oxygen species (ROS) exerting cytotoxic action on tumor cells. Here we present the synthesis and the study of the in vitro photodynamic effects of two BODIPYs which differ in the structure of the substituent placed on the meso (or 8) position of the dipyrrolylmethenic nucleus. The two compounds were tested on three human cancer cell lines of different origin and degree of malignancy. Our results indicate that the BODIPYs are very effective in reducing the growth/viability of HCT116, SKOV3 and MCF7 cells when irradiated with a green LED source, whereas they are practically devoid of activity in the dark. Phototoxicity occurs mainly through apoptotic cell death, however necrotic cell death also seems to play a role. Furthermore, singlet oxygen generation and induction of the increase of reactive oxygen species also appear to be involved in the photodynamic effect of the BODIPYs. Finally, it is worth noting that the two BODIPYs are also able to exert anti-migratory activity.

Protoporphyrin IX is a dual inhibitor of p53/MDM2 and p53/MDM4 interactions and induces apoptosis in B-cell chronic lymphocytic leukemia cells

p53 is a tumor suppressor, which belongs to the p53 family of proteins. The family consists of p53, p63 and p73 proteins, which share similar structure and function. Activation of wild-type p53 or TAp73 in tumors leads to tumor regression, and small molecules restoring the p53 pathway are in clinical development. Protoporphyrin IX (PpIX), a metabolite of aminolevulinic acid, is a clinically approved drug applied in photodynamic diagnosis and therapy. PpIX induces p53-dependent and TAp73-dependent apoptosis and inhibits TAp73/MDM2 and TAp73/MDM4 interactions. Here we demonstrate that PpIX is a dual inhibitor of p53/MDM2 and p53/MDM4 interactions and activates apoptosis in B-cell chronic lymphocytic leukemia cells without illumination and without affecting normal cells. PpIX stabilizes p53 and TAp73 proteins, induces p53-downstream apoptotic targets and provokes cancer cell death at doses non-toxic to normal cells. Our findings open up new opportunities for repurposing PpIX for treating lymphoblastic leukemia with wild-type TP53.

p53-Dependent and p53-Independent Responses of Cells Challenged by Photosensitization

The p53 protein exerts fundamental roles in cell responses to a variety of stress stimuli. It has clear roles in controlling cell cycle, triggering apoptosis, activating autophagy and modulating DNA damage response. Little is known about the role of p53 in autophagy-associated cell death, which can be induced by photoactivation of photosensitizers within cells. The photosensitizer 1,9-dimethyl methylene blue (DMMB) within nanomolar concentration regimes has specific intracellular targets (mitochondria and lysosomes), photoinducing a typical scenario of cell death with autophagy. Importantly, in consequence of its subcellular localization, photoactive DMMB induces selective damage to mitochondrial DNA, saving nuclear DNA. By challenging cells having different p53 protein levels, we investigated whether p53 modulates DMMB/light-induced phototoxicity and cell cycle dynamics. Cells lacking p53 activity were slightly more resistant to photoactivated DMMB, which was correlated with a smaller sub-G1 population, indicative of a lower level of apoptosis. DMMB photosensitization seems to induce mostly autophagy-associated cell death and S-phase cell cycle arrest with replication stress. Remarkably, these responses were independent on the p53 status, indicating that p53 is not involved in either process. Despite describing some p53-related responses in cells challenged by photosensitization, our results also provide novel information on the consequences of DMMB phototoxicity.

A preclinical model to investigate the role of surgically-induced inflammation in tumor responses to intraoperative photodynamic therapy

OBJECTIVE

Inflammation is a well-known consequence of surgery. Although surgical debulking of tumor is beneficial to patients, the onset of inflammation in injured tissue may impede the success of adjuvant therapies. One marker for postoperative inflammation is IL-6, which is released as a consequence of surgical injuries. IL-6 is predictive of response to many cancer therapies, and it is linked to various molecular and cellular resistance mechanisms. The purpose of this study was to establish a murine model by which therapeutic responses to photodynamic therapy (PDT) can be studied in the context of surgical inflammation.

MATERIALS AND METHODS

Murine models with AB12 mesothelioma tumors were treated with either surgical resection or sham surgery with tumor incision but no resection. The timing and extent of IL-6 release in the tumor and/or serum was measured using enzyme-linked immunosorbent assay (ELISA) and compared to that measured in the serum of 27 consecutive, prospectively enrolled patients with malignant pleural mesothelioma (MPM) who underwent macroscopic complete resection (MCR).

RESULTS

MPM patients showed a significant increase in IL-6 at the time MCR was completed. Similarly, IL-6 increased in the tumor and serum of mice treated with surgical resections. However, investigations that combine resection with another therapy make it necessary to grow tumors for resection to a larger volume than those that receive secondary therapy alone. As the larger size may alter tumor biology independent of the effects of surgical injury, we assessed the tumor incision model. In this model, tumor levels of IL-6 significantly increased after tumor incision.

CONCLUSION

The tumor incision model induces IL-6 release as is seen in the surgical setting, yet it avoids the limitations of surgical resection models. Potential mechanisms by which surgical induction of inflammation and IL-6 could alter the nature and efficacy of tumor response to PDT are reviewed. These include a wide spectrum of molecular and cellular mechanisms through which surgically-induced IL-6 could change the effectiveness of therapies that are combined with surgery. The tumor incision model can be employed for novel investigations of the effects of surgically-induced, acute inflammation on therapeutic response to PDT (or potentially other therapies). Lasers Surg. Med. 50:440-450, 2018. © 2018 Wiley Periodicals, Inc.

Wild-type and mutant p53 differentially modulate miR-124/iASPP feedback following pohotodynamic therapy in human colon cancer cell line

Colorectal cancer (CRC) is a most common digestive system malignant tumor. p53 mutation has essential role in cancers and is frequently observed in CRC and presents a huge challenge. p53 mutation has been reported to attenuate the inhibitory effect of photofrin-based photodynamic therapy (PDT). p53 mutation-induced gain of function brings up the dysfunction of carcinogenic factors, including miRNAs. Our research found that PDT suppressed CRC cell viability, reduced the tumor size and prolonged the survival time, all of which could be attenuated by p53 mutation or deletion. After p53 mutation or deletion, several miRNA expression levels were downregulated, among which miR-124 was the most strongly downregulated, whereas iASPP expression was upregulated. p53 binds to the promoter of miR-124 to promote its expression and then inhibited iASPP expression, so as to amplify the inhibitory effect of PDT on wild-type p53 cells. In p53-mutant or -deleted cells, this binding no longer worked to promote miR-124 expression, and iASPP expression increased, finally resulted in promoted CRC cell viability upon PDT. The interactive modulation among miR and iASPP in p53-mutant or -deleted cells may serve as a crucial pathway, which mediates therapy resistance when p53 is mutated or deleted, in the process of PDT treatment of CRC.

Photodynamic therapy in colorectal cancer treatment--The state of the art in preclinical research

BACKGROUND

Photodynamic therapy (PDT) is used in many different oncologic fields. Also in gastroenterology, where have been a few attempts to treat both the premalignant lesion and advanced colorectal cancer (CRC). This review aims to give a general overview of preclinical photodynamic studies related to CRC cells and animal studies of photodynamic effects related to CRC treatment to emphasize their potential in study of PDT mechanism, safety and efficiency to translate these results into clinical benefit in CRC treatment.

MATERIALS AND METHOD

Literature on in vitro preclinical photodynamic studies related to CRC cells and animal studies of photodynamic effects related to CRC treatment with the fallowing medical subject headings search terms: colorectal cancer, photodynamic therapy, photosensitizer(s), in vitro, cell culture(s), in vivo, animal experiment(s). The articles were selected by their relevance to the topic.

RESULTS

The majority of preclinical studies concerning possibility of PDT application in colon and rectal cancer is focused on phototoxic action of photosensitizers toward cultured colorectal tumor cells in vitro. The purposes of animal experiments are usually elucidation of mechanisms of observed photodynamic effects in scale of organism, estimation of PDT safety and efficiency and translation of these results into clinical benefit.

CONCLUDING REMARKS

In vitro photodynamic studies and animal experiments can be useful for studies of mechanisms and efficiency of photodynamic method as a start point on PDT clinical research. The primary disadvantage of in vitro experiments is a risk of over-interpretation of their results during extrapolation to the entire CRC.

p53 family members - important messengers in cell death signaling in photodynamic therapy of cancer?

TP53 is one of the genes most frequently inactivated in cancers. Mutations in TP53 gene are linked to worse prognosis and shorter overall survival of cancer patients. TP53 encodes a critical tumor suppressor, which dictates cell fate decisions upon stress stimuli. As a sensor of cellular stress, p53 is a relevant messenger of cell death signaling in ROS-driven photodynamic therapy (PDT) of cancer. The significant role of p53 in response to PDT has been reported for several clinically approved photosensitizers. Multiple reports described that wild-type p53 contributes to cell killing upon photodynamic therapy with clinically approved photosensitizers but the mechanism is still not fully understood. This work outlines the diverse functions of p53 family members in cancer cells' susceptibility and resistance to PDT. In summary p53 and p53 family members are emerging as important mediators of cell death signaling in photodynamic therapy of cancer, however the mechanism of cell death provoked during PDT might differ depending on the tissue type and the photosensitizer applied.

The role of p53 in the response of tumor cells to sonodynamic therapy in vitro

p53 plays a pivotal role in apoptosis. In addition, p53 is currently extensively investigated as a promising strategy for highly specific anticancer therapy in chemotherapeutics and photodynamic therapy. However, the role of p53 in the response of tumor cells to sonodynamic therapy treatment is still unclear. In this study, we aim to investigate the activation of p53 in sonodynamic therapy. Three murine tumor models with distinct aggressiveness (S180, H-22 and EAC) were treated with 1.75MHz continuous ultrasound at an acoustic intensity (I(SATA)) of 1.4W for 3min in the presence of 20μg/ml hematoporphyrin. The DNA fragment and nuclear damage were observed by TUNEL and single cell gel electrophoresis. Western blotting and RT-PCR were used to analyze the expression of p53, PUMA, Bax and Fas. Then we checked the translocation of p53 by confocal microscopy. DNA sequencing was used to determine the status of p53 gene in three tumor cell lines. Our results indicated that the level of p53 protein and mRNA increased significantly, and p53 activated the expression of its downstream pro-apoptosis gene PUMA, Bax and Fas in the S180 and H-22 cells. Meanwhile, p53 protein translocated onto mitochondria. In the EAC cells, expression and translocation of p53 was not found; the level of PUMA, Bax and Fas remained unaltered. The S180 cells showed most serious DNA fragment and nuclear damage with 77.43% TDNA; H-22 cells in the middle with 58.85% TDNA; whereas EAC cells appeared less nuclear material lost with just 15.82% TDNA. The results of DNA sequencing showed that the sequences of exons 5-8 of the p53 gene of S180, H-22 and EAC cells were the same with the sequences of wild-type p53 provided by NCBI. These results primarily demonstrated that: (1) p53 was activated to promote SDT-induced apoptosis through extrinsic and intrinsic signaling pathways in the S180 and H-22 cells; (2) cellular responses of different cells to SDT were distinct, the aggressive S180 cells were much more sensitive than H-22, whereas EAC cells were relatively less sensitive. The discrepancy among the cell lines may be due to different activation time of p53 protein.

Mechanisms of resistance to photodynamic therapy

Photodynamic therapy (PDT) involves the administration of a photosensitizer (PS) followed by illumination with visible light, leading to generation of reactive oxygen species. The mechanisms of resistance to PDT ascribed to the PS may be shared with the general mechanisms of drug resistance, and are related to altered drug uptake and efflux rates or altered intracellular trafficking. As a second step, an increased inactivation of oxygen reactive species is also associated to PDT resistance via antioxidant detoxifying enzymes and activation of heat shock proteins. Induction of stress response genes also occurs after PDT, resulting in modulation of proliferation, cell detachment and inducing survival pathways among other multiple extracellular signalling events. In addition, an increased repair of induced damage to proteins, membranes and occasionally to DNA may happen. PDT-induced tissue hypoxia as a result of vascular damage and photochemical oxygen consumption may also contribute to the appearance of resistant cells. The structure of the PS is believed to be a key point in the development of resistance, being probably related to its particular subcellular localization. Although most of the features have already been described for chemoresistance, in many cases, no cross-resistance between PDT and chemotherapy has been reported. These findings are in line with the enhancement of PDT efficacy by combination with chemotherapy. The study of cross resistance in cells with developed resistance against a particular PS challenged against other PS is also highly complex and comprises different mechanisms. In this review we will classify the different features observed in PDT resistance, leading to a comparison with the mechanisms most commonly found in chemo resistant cells.

Utility of biomarkers in prediction of response to ablative therapy in Barrett's esophagus

BACKGROUND & AIMS

Photodynamic therapy (PDT) has been shown to be effective in the treatment of high-grade dysplasia (HGD)/mucosal carcinoma in Barrett's esophagus (BE). Substantial proportions of patients do not respond to PDT or progress to carcinoma despite PDT. The role of biomarkers in predicting response to PDT is unknown. We aimed to determine if biomarkers known to be associated with neoplasia in BE can predict loss of dysplasia in patients treated with ablative therapy for HGD/intramucosal cancer.

METHODS

Patients with BE and HGD/intramucosal cancer were studied prospectively from 2002 to 2006. Biomarkers were assessed using fluorescence in situ hybridization performed on cytology specimens, for region-specific and centromeric probes. Patients were treated with PDT using cylindric diffusing fibers (wavelength, 630 nm; energy, 200 J/cm fiber). Univariate and multiple variable logistic regression was performed to determine predictors of response to PDT.

RESULTS

A total of 126 consecutive patients (71 who underwent PDT and 55 patients who did not undergo PDT and were under surveillance, to adjust for the natural history of HGD), were included in this study. Fifty (40%) patients were responders (no dysplasia or carcinoma) at 3 months after PDT. On multiple variable analysis, P16 allelic loss (odds ratio [OR], 0.32; 95% confidence interval [CI], 0.10-0.96) predicted decreased response to PDT. BE segment length (OR, 0.71; 95% CI, 0.59-0.85), and performance of PDT (OR, 7.17; 95% CI, 2.50-20.53) were other independent predictors of loss of dysplasia.

CONCLUSIONS

p16 loss detected by fluorescence in situ hybridization can help predict loss of dysplasia in patients with BE and HGD/mucosal cancer. Biomarkers may help in the selection of appropriate therapy for patients and improve treatment outcomes.

Early apoptosis and cell death induced by ATX-S10Na (II)-mediated photodynamic therapy are Bax- and p53-dependent in human colon cancer cells

AIM: To investigate the roles of Bax and p53 proteins in photosensitivity of human colon cancer cells by using lysosome-localizing photosensitizer, ATX-S10Na (II).

METHODS: HCT116 human colon cancer cells and Bax-null or p53-null isogenic derivatives were irradiated with a diode laser. Early apoptosis and cell death in response to photodynamic therapy were determined by MTT assays, annexin V assays, transmission electron microscopy assays, caspase assays and western blotting.

RESULTS: Induction of early apoptosis and cell death was Bax- and p53-dependent. Bax and p53 were required for caspase-dependent apoptosis. The levels of anti-apoptotic Bcl-2 family proteins, Bcl-2 and Bcl-x_L, were decreased in Bax- and p53-independent manner.

CONCLUSION: Our results indicate that early apoptosis and cell death of human colon cancer cells induced by photodynamic therapy with lysosome-localizing photosensitizer ATX-S10Na (II) are mediated by p53-Bax network and low levels of Bcl-2 and Bcl-x_L proteins. Our results might help in formulating new therapeutic approaches in photodynamic therapy.

p53 Status does not affect photodynamic cell killing induced by hypericin

PURPOSE

Given that p53 is a tumor suppressor that plays a central role in the cellular response to DNA damage and that more than 50% of all cancers have mutated p53, the wider utility of photodynamic therapy (PDT) in the treatment of cancer will depend on an understanding of whether p53 status modulates response to PDT. In this study, we investigated the photosensitivity of isogenic cell lines that differ only in their p53 status to PDT using hypericin as the photosensitizer.

METHODS

Acute (MTT) and chronic (clonogenic) cytotoxic assays were performed on two osteosarcoma cell-lines (U2OS and U2OS+p53DD) that are isogenic except that the latter expresses dominant negative p53. The inducible expression of p53 was determined on western blots. Uptake of hypericin, cell cycle profile analysis, measurement of membrane phosphatidylserine externalization and changes in mitochondrial membrane potential were investigated using flow cytometry.

RESULTS

Hypericin uptake was observed to be equivalent in U2OS and U2OS+p53DD cells. There were no significant differences in cell killing between these cell-lines in both the MTT and clonogenic assays (IC(50) of 0.4 microg/ml from MTT assay). p53 expression did not increase up to 24 h after PDT treatment in both cell lines. There were also no significant differences in the cell-cycle arrest profiles and timing of onset of apoptosis.

CONCLUSIONS

Taken together, these results suggest that the status of p53 may not be important in PDT-mediated cell killing or induction of apoptosis. By extension, these results imply that PDT may be used with equal efficacy for the treatment of p53-positive and -negative tumors.

Alterations in mitochondrial and apoptosis-regulating gene expression in photodynamic therapy-resistant variants of HT29 colon carcinoma cells

Photodynamic therapy (PDT) is a novel cancer therapy inducing irreversible photodamage to tumor tissue via photosensitizer-mediated oxidative cytotoxicity. The cellular and molecular responses associated with PDT are only partially understood. We have reported previously the generation of several photosensitizer-specific PDT-resistant cell variants of HT29 human colon adenocarcinoma cells by selecting cells from sequential PDT treatment using different photosensitizers. In this report, we describe the use of messenger RNA (mRNA) differential display to identify genes that were differentially expressed in the parental HT29 cells compared with their resistant variants. In comparison with parental HT29 cells, mRNA expression was increased in the PDT-resistant cell variants for BNIP3, estrogen receptor-binding fragment-associated gene 9, Myh-1c, cytoplasmic dynein light chain 1, small membrane protein I and differential dependent protein. In contrast, expression in the PDT-resistant variants was downregulated for NNX3, human HepG2 3' region Mbol complementary DNA, glutamate dehydrogenase, hepatoma-derived growth factor and the mitochondrial genes coding for 16S ribosomal RNA (rRNA) and nicotinamide adenine dinucleotide (NADH) dehydrogenase subunit 4. The reduction for mitochondrial 16S rRNA in the PDT-resistant variants was confirmed by Northern blotting, and the elevated expression of the proapoptotic BNIP3 in the PDT-resistant variants was confirmed by Northern and Western blotting analysis. We also examined the expression of some additional apoptosis-regulating genes using Western blotting. We show an increased expression of Bcl-2 and heat shock protein 27 and a downregulation of Bax in the PDT-resistant variants. In addition, the mutant p53 levels in the parental HT29 cells were reduced substantially in the PDT-resistant variants. We suggest that the altered expression in several mitochondrial and apoptosis-regulating genes contributes to PDT resistance.

Uses of photodynamic therapy in premalignant and malignant lesions of the gastrointestinal tract beyond the esophagus

Much has recently been written regarding the use of photodynamic therapy for the treatment of esophageal carcinoma and dysplastic Barrett's esophagus. This review, however, describes the clinical experience using photodynamic therapy with various photosensitizer agents for the treatment of diseases in other areas of the gut, especially the pancreaticobiliary tract where European studies have established the role of porfimer sodium photodynamic therapy in the management of patients with cholangiocarcinoma.

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Cellular uptake, localization and photodynamic effects of haematoporphyrin derivative in human glioma and squamous carcinoma cell lines

Uptake, intracellular concentration, localization and photodynamic effects of a haematoporphyrin derivative (HpD, Photosan-3) were compared in human glioma (BMG-1, wild-type p53) and squamous carcinoma (4451, mutated p53) cell lines. Concentration and time dependence of cellular uptake of HpD was assayed from methanol extracts and whole cell suspension spectroscopy, while localization was studied by fluorescence microscopy-based image analysis. Colony-forming ability, apoptosis, cell-cycle progression and cytogenetic damage (micronuclei formation) were investigated as parameters of photodynamic response following irradiation with red light. BMG-1 cells were more sensitive to the photodynamic treatment than 4451 cells, although the 4451 cells accumulated a higher amount of HpD and did not differ significantly from BMG-1 cells with respect to intracellular localization. Photodynamically-induced cytogenetic damage and apoptosis were considerably higher in BMG-1 cells as compared to 4451 cells. The present results strongly suggest that manifestation of the photodynamically-induced lesions in the form of cytogenetic damage and apoptosis are among the important determinants of cellular sensitivity to HpD-PDT besides the photodynamic dose (intracellular concentration of the photosensitizer and the light dose).

The role of apoptosis in response to photodynamic therapy: what, where, why, and how

Photodynamic therapy (PDT), a treatment for cancer and for certain benign conditions, utilizes a photosensitizer and light to produce reactive oxygen in cells. PDT is primarily employed to kill tumor and other abnormal cells, so it is important to ask how this occurs. Many of the photosensitizers currently in clinical or pre-clinical studies of PDT localize in or have a major influence on mitochondria, and PDT is a strong inducer of apoptosis in many situations. The purpose of this review is to critically evaluate all of the recently published research on PDT-induced apoptosis, with a focus on studies providing mechanistic insights. Components of the mechanism whereby PDT causes cells to undergo apoptosis are becoming understood, as are the influences of several signal transduction pathways on the response. Future research should be directed to elucidating the role(s) of the multiple steps in apoptosis in directing damaged cells to an apoptotic vs. necrotic pathway and for producing tumor ablation in conjunction with tissue-level mechanisms operating in vivo.

Outcome of patients receiving photodynamic therapy for early esophageal cancer

PURPOSE

Photodynamic therapy (PDT) has shown remarkable activity in a variety of human cancers. In the present study, we report the effects of PDT on inoperable early-stage esophageal cancer.

METHODS AND MATERIALS

Sixty-two patients were treated with an argon dye laser (630 nm wavelength, 300-800 mW of power, energy dose of 200-300 J/cm) after intravenous injection of 5 mg/kg of hematoporphyrin derivative. Eighteen patients (29.5%) had in situ carcinoma (Tis), 30 (48.5%) had T1-stage cancer, 7 (11%) had T2-stage cancer, and 7 (11%) had recurrent disease in the anastomotic area after previous surgery without evidence of invasion outside the lumen. Patients with residual disease after two rounds of PDT received definitive radiotherapy. Patients were evaluated for response to therapy and survival. The follow-up time ranged from 3 to 90 months (median, 32 months).

RESULTS

The complete response (CR) rate was 37% (23 of 62) in patients who received PDT alone and 82% (51 of 62) in those who also received radiotherapy. The CR rate after PDT alone was statistically higher (p = 0.04) for patients who had Tis/T1 lesions (21 of 48; 44%) than for those with T2-stage disease (2 of 7; 28%) or recurrent tumors (0 of 7; 0%). Fifty-two percent of patients who had CR following PDT alone did not suffer local tumor recurrence. The median local progression-free survival times after PDT and additional radiotherapy (in cases with incomplete response) was 49 months for Tis- and T1-stage lesions, 30 months for those with T2-stage disease, and 14 months for patients with locally recurrent disease. Patients who completely responded to PDT had a median overall survival (OS) of 50 months, which was significantly longer (p < 0.003) than that of patients not responding to PDT. Toxicity was minimal; we recorded three cases of esophageal stenosis (7%) and one case of tracheo-esophageal fistula (2.5%) after combined PDT and radiotherapy.

CONCLUSION

PDT is an effective regimen for early esophageal cancer, giving a CR rate of about 40%, long-term local control and favorable overall survival. Additional radiotherapy in cases of incomplete response to PDT is effective and potentially curative in another 45% of cases.

Photodynamic therapy

Photodynamic therapy involves administration of a tumor-localizing photosensitizing agent, which may require metabolic synthesis (i.e., a prodrug), followed by activation of the agent by light of a specific wavelength. This therapy results in a sequence of photochemical and photobiologic processes that cause irreversible photodamage to tumor tissues. Results from preclinical and clinical studies conducted worldwide over a 25-year period have established photodynamic therapy as a useful treatment approach for some cancers. Since 1993, regulatory approval for photodynamic therapy involving use of a partially purified, commercially available hematoporphyrin derivative compound (Photofrin) in patients with early and advanced stage cancer of the lung, digestive tract, and genitourinary tract has been obtained in Canada, The Netherlands, France, Germany, Japan, and the United States. We have attempted to conduct and present a comprehensive review of this rapidly expanding field. Mechanisms of subcellular and tumor localization of photosensitizing agents, as well as of molecular, cellular, and tumor responses associated with photodynamic therapy, are discussed. Technical issues regarding light dosimetry are also considered.