Predictive biomarkers for 5-ALA-PDT can lead to personalized treatments and overcome tumor-specific resistances

Potential therapeutic efficacy of photodynamic therapy on female hormonal-dependent cancers in a hormonal simulated microenvironment

BACKGROUND

Photodynamic Therapy (PDT) is a clinically approved cancer treatment. Sex hormones, the key drivers for the development of female hormonal dependent cancers, might affect cancer treatment. There are seldom studies to evaluate the effect of sex hormones mimicked the menstrual cycle on the PDT mediated by prodrug 5-aminolevulinic acid (ALA) and its ester derivatives to the hormonal dependent cancers.

AIMS

To evaluate the efficacy of sex hormones on Hexyl-ALA-PDT in hormonal dependent cancers and the effect of the sex hormones on heme biosynthetic pathway.

METHODS

Cell culture system that mimicked the fluctuation of sex hormones 17β-estradiol (E2) and progesterone (PG) in the menstrual cycle was developed. Two pairs of hormonal-independent and hormonal dependent uterine sarcoma and breast cancer cell lines were used as cell models. Hexyl-ALA induced PpIX production and intracellular localization were examined. Key enzymes for PpIX synthesis were analysed. Hexyl-ALA-PDT mediated phototoxicity was evaluated.

RESULTS

The PpIX generation was increased in the hormonal-dependent cells (28-50 %) when cultured in the hormonal microenvironment with long incubation of Hexyl-ALA for 15 and 24 h compared to that cultured without hormones; whereas only slight difference in PpIX generation in their hormonal-independent counterpart. The PpIX generation was in a time-dependent manner. The CPOX, PPOX and FECH expressions were significantly enhanced by Hexyl-ALA-PDT in uterine sarcoma cells in hormonal microenvironment. Hexyl-ALA-PDT triggered significant increase of PPOX expression in breast cancer cells in hormonal microenvironment. The Hexyl-ALA-PDT phototoxicity was enhanced by 18-40 % in cells cultured in the hormonal system in a dose-dependent manner.

CONCLUSION

The PpIX generation and the efficacy of Hexyl-ALA-PDT in both uterine sarcoma and breast cancer cells was significantly enhanced by the sex hormones via cultured in the hormonal microenvironment.

In vitro evaluation of the efficacy of photodynamic therapy using 5-ALA on homologous feline mammary tumors in 2D and 3D culture conditions and a mouse subcutaneous model with 3D cultured cells

BACKGROUND

Numerous studies have shown that photodynamic therapy (PDT) has a therapeutic effect on mammary tumor cells, with 5-aminolevulinic acid (5-ALA-HCL) being a commonly used photosensitizer for PDT. Feline mammary tumors (FMTs) are relatively common. However, the cytotoxic and antitumor effects of 5-ALA-PDT on FMTs have not been clarified. To this end, we evaluated the therapeutic effect of 5-ALA-PDT on FMTs through in vitro experiments using an FMT FKR cell line established for this study.

METHODS

We performed 5-ALA-PDT in 2D-cultured FKR-A (adherent cells) and 3D-cultured FKR-S (spheroid cells) cells and performed a series of studies to evaluate the cell viability and determine the protoporphyrin IX (PpIX) content in the cells as well as the expression levels of mRNAs associated with PpIX production and release. An in vivo study was performed to assess the effectiveness of 5-ALA-PDT.

RESULTS

There was a significant difference in the concentration of PpIX in FMT cells under different incubation culture modes (2D versus 3D culture). The concentration of PpIX in FMT cells was correlated with the differences in cell culture (2D and 3D) as well as the expression levels of genes such as PEPT1, PEPT2, FECH, and HO-1.

CONCLUSIONS

In the in vitro study, 5-ALA-PDT had a stronger inhibitory effect on 3D-cultured FKR-S cells, which resemble the internal environment of organisms more closely. We also observed a significant inhibitory effect of 5-ALA-PDT on FMT cells in vivo. To our knowledge, this is the first study on 5-ALA-PDT for FMTs under both 2D and 3D conditions.

Optimized complete cytoreduction in ovarian cancer through intraoperative real-time tumor visualization by 5-ALA - a case report

Introduction

Complete macroscopic cytoreduction represents the most important prognostic parameter for overall survival in ovarian cancer. This dogma remains tenacious despite significant improvements in adjuvant systemic treatment. Hence, optimization of surgical therapy is an overarching goal to improve patients' outcomes. In this context, intraoperative tumor-specific imaging might facilitate optimized cytoreduction. In neurosurgery, intraoperative 5-aminolevulinic acid (5-ALA) guided imaging is applied in clinical routine to assess surgical resection margins. Here, we report the case of a patient with ovarian cancer in whom intraoperative 5-ALA tumor visualization led to optimized complete cytoreduction.

Objective

Intraoperative administration of 5-ALA led to improved complete cytoreduction by identification and resection of additional ovarian cancer tumor manifestations.

Case

The 39-year-old patient, Jehovah`s witness, presented to our department with a left sided ovarian mass, suspicious of ovarian cancer, based on clinical examination, sonographic suspicious features and a CA12-5 elevation. The patient's medical history and family history was unremarkable. Preoperative CT imaging of the thorax and abdomen showed no pathology besides the adnexal mass. Surgery was performed by a midline laparotomy with hysterectomy, bilateral adnexectomy, pelvic peritonectomy, omentectomy, ureterolysis, diaphragm stripping, adhesiolysis and the collection of peritoneal and rectal samples. Intraoperative 5-ALA imaging using a dedicated excitation and detection loupe system (Reveal, DVI) led to tumor detection at the diaphragm, the omentum and the rectum that was not detectable by palpation and visualization using white light. The pathology results revealed that the 5-ALA positive samples (diaphragm, rectum and omentum) obtained by intraoperative 5-ALA were positive for ovarian cancer.

Conclusion

Intraoperative administration of 5-ALA represents a promising approach to improve complete cytoreduction in ovarian cancer surgery thereby improving clinical outcomes. Hence, further research and clinical trials are required to investigate the potential of intraoperative 5-ALA imaging in ovarian cancer debulking surgery and its impact on long-term clinical outcomes.

Cell senescence-associated porphyrin metabolism affects the efficacy of aminolevulinic acid-photodynamic diagnosis in bladder cancer

Aminolevulinic acid-photodynamic diagnosis (ALA-PDD) is a promising alternative method to detect cancer cells because of its high specificity and low rate of side effects. Exogenous ALA is administered and accumulates as protoporphyrin IX (PpIX) in cancer cells, which then emit red fluorescence following light irradiation to enable surgeons to accurately identify and remove cancerous tissue. Recent reports suggested that PpIX failed to accumulate in some patients who underwent ALA-PDD. We hypothesized that cell senescence, which is a relatively inactive state, affects porphyrin accumulation in bladder cancer cells. In this study, we evaluated the relationship between cell senescence and porphyrin accumulation in affecting the efficacy of ALA-PDD. First, we utilized three bladder cancer cell lines to evaluate senescence-related indicators and establish a cell senescence model. Then, we identified the differences in porphyrin production and the proteins involved in porphyrin accumulation between old and young cells. We found that compared with young cells, old cells possessed higher concentration of PpIX and had lower ABCG2 expression. The increase in PpIX levels following ABCG2 inhibition is three times higher in old cells than in young cells, suggesting that cell senescence was closely related with porphyrin accumulation in cancer. In conclusion, we found that the efficacy of ALA-PDD and porphyrin accumulation was relatively high in senescent cancer cells and that inhibition of ABCG2 could improve the efficacy of ALA-PDD in young bladder cancer cells.

5 ALA Is a Potent Lactate Dehydrogenase Inhibitor But Not a Substrate: Implications for Cell Glycolysis and New Avenues in 5 ALA-Mediated Anticancer Action

Simple Summary

In the present work, we found that 5-ALA, a natural precursor of heme, can hinder cell glycolysis, which is the main path of energy production for most cancer cells. More specifically, we found that 5-ALA can block an enzyme involved in glycolysis, called lactate dehydrogenase (LDH). We found that 5-ALA has a potency of LDH inhibition comparable to other established LDH inhibitors, such as oxamate or tartronic acid. Nevertheless, 5-ALA has a high accumulation rate in cancers and specifically in the incurable brain cancer glioblastoma multiforme (GBM), which is an important advantage. In fact, because of its high specificity to GBM, 5-ALA is used in the clinic to accurately guide the resection of the tumours, through the light emission of its photoactive product protoporphyrin IX (PpIX). PpIX is the penultimate step in the heme production. Importantly, we show here that continuous administration of 5-ALA killed GBM cells according to their dependence on glycolysis. We additionally found that 20% of externally administered 5-ALA is engaged in the inhibition of LDH, as when LDH was pre-loaded by another inhibitor, tartronic acid, then the cell production of PpIX from 5-ALA was increased by 20%. Since PpIX is an important drug for photodynamic therapy of cancer (excitation by light of PpIX produces oxygen by-products that can kill cancer cells), we additionally discovered that preloading LDH with its inhibitor tartronic acid before performing 5-ALA PDT increases the cancer cell death by 15%.

Abstract

In a course of metabolic experiments, we determined that the addition of δ-aminolevulinic acid (5-ALA) to a panel of glioblastoma multiforme (GBM) cells caused a steep reduction in their glycolytic activity. This reduction was accompanied by a decrease in adenosine triphosphate (ATP) production from glycolysis. These results suggested that 5-ALA is an inhibitor of glycolysis; due to the structural similarity of 5-ALA to the established lactate dehydrogenase (LDH) inhibitors oxamate (OXM) and tartronate (TART), we initially investigated LDH inhibition by 5-ALA in silico. The modelling revealed that 5-ALA could indeed be a competitive inhibitor of LDH but not a substrate. These theoretical findings were corroborated by enzymatic and cell lysate assays in which 5-ALA was found to confer a potent LDH inhibition comparable to that of OXM and TART. We subsequently evaluated the effect of 5-ALA-induced glycolysis inhibition on the viability of GBM cells with diverse metabolic phenotypes. In the Warburg-type cell lines Ln18 and U87, incubation with 5-ALA elicited profound and irreversible cell death (90–98%) at 10 mM after merely 24 h. In T98G, however, which exhibited both high respiratory and glycolytic rates, LD95 was achieved after 72 h of incubation with 20 mM 5-ALA. We additionally examined the production of the 5-ALA photosensitive metadrug protoporphyrin IX (PpIX), with and without prior LDH inhibition by TART. These studies revealed that ~20% of the 5-ALA taken up by the cells was engaged in LDH inhibition. We subsequently performed 5-ALA photodynamic therapy (PDT) on Ln18 GBM cells, again with and without prior LDH inhibition with TART, and found a PDT outcome enhancement of ~15% upon LDH pre-inhibition. We expect our findings to have a profound impact on contemporary oncology, particularly for the treatment of otherwise incurable brain cancers such as GBM, where the specific accumulation of 5-ALA is very high compared to the surrounding normal tissue.

Synthesis and applications of [60]fullerene nanoconjugate with 5-aminolevulinic acid and its glycoconjugate as drug delivery vehicles

The 5-aminolevulinic acid (5-ALA) prodrug is widely used in clinical applications, primarily for skin cancer treatments and to visualize brain tumors in neurosurgery. Unfortunately, its applications are limited by unfavorable pharmacological properties, especially low lipophilicity; therefore, efficient nanovehicles are needed. For this purpose, we synthesized and characterized two novel water-soluble fullerene nanomaterials containing 5-ALA and d-glucuronic acid components. Their physicochemical properties were investigated using NMR, XPS, ESI mass spectrometry, as well as TEM and SEM techniques. In addition, HPLC and fluorescence measurements were performed to evaluate the biological activity of the fullerene nanomaterials in 5-ALA delivery and photodynamic therapy (PDT); additional detection of selected mRNA targets was carried out using the qRT-PCR methodology. The cellular response to the [60]fullerene conjugates resulted in increased levels of ABCG2 and PEPT-1 genes, as determined by qRT-PCR analysis. Therefore, we designed a combination PDT approach based on two fullerene materials, C₆₀-ALA and C₆₀-ALA-GA, along with the ABCG2 inhibitor Ko143.

Molecular Effectors of Photodynamic Therapy-Mediated Resistance to Cancer Cells

Photodynamic therapy (PDT) is currently enjoying considerable attention as the subject of experimental research to treat resistant cancers. The preferential accumulation of a non-toxic photosensitizer (PS) in different cellular organelles that causes oxidative damage by combining light and molecular oxygen leads to selective cell killing. However, one major setback, common among other treatment approaches, is tumor relapse and the development of resistance causing treatment failure. PDT-mediated resistance could result from increased drug efflux and decreased localization of PS, reduced light exposure, increased DNA damage repair, and altered expression of survival genes. This review highlights the essential insights of PDT reports in which PDT resistance was observed and which identified some of the molecular effectors that facilitate the development of PDT resistance. We also discuss different perceptions of PDT and how its current limitations can be overturned to design improved cancer resistant treatments.

Investigation of the therapeutic effect of 5-aminolevulinic acid based photodynamic therapy on hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a heterogeneous type of cancer and current treatment options limit successful therapy outcomes. Photodynamic therapy (PDT) has attracted attention as an alternative approach in the treatment of different types of cancer. However, there is no study in the literature regarding the effect of PDT on HCC, in vitro. Therefore, the aim of this study was to determine the cytotoxic and apoptotic effects of 5-aminolevulinic acid (5-ALA)/PDT on two different HCC cell lines in terms of hepatitis B virus (HBV) infection. The therapeutic effects of 5-ALA-based PDT on HCC cell lines (Huh-7 and SNU-449) were evaluated by PpIX-fluorescence accumulation, WST-1 analysis, Annexin V analysis, and acridine orange/ethidium bromide staining after irradiation with different light doses through diode laser. The results showed that 1 mM 5-ALA displayed higher PpIX fluorescence in the SNU-449 cell line than the Huh-7 cell line after 4 h of incubation. After irradiation with different light doses (3, 6, 9, and 12 J/cm²), 5-ALA significantly reduced the proliferation of HCC cells and induced apoptotic cell death (p < 0.01). Furthermore, SNU-449 cells were more responsive to 5-ALA-based PDT than Huh-7 cells due to possibly its molecular features as well as viral HBV status. Our preliminary data obtained from this study may contribute to the development of 5-ALA/PDT-based treatment strategies in the treatment of HCC. However, this study could be improved by the elucidation of the molecular mechanisms of cell death induced by 5-ALA/PDT in HCC cells, the use of different photosensitizer, light sources, and in vivo experiments.

Perspectives on interstitial photodynamic therapy for malignant tumors

SIGNIFICANCE

Despite remarkable advances in the core modalities used in combating cancer, malignant diseases remain the second largest cause of death globally. Interstitial photodynamic therapy (IPDT) has emerged as an alternative approach for the treatment of solid tumors.

AIM

The aim of our study is to outline the advancements in IPDT in recent years and provide our vision for the inclusion of IPDT in standard-of-care (SoC) treatment guidelines of specific malignant diseases.

APPROACH

First, the SoC treatment for solid tumors is described, and the attractive properties of IPDT are presented. Second, the application of IPDT for selected types of tumors is discussed. Finally, future opportunities are considered.

RESULTS

Strong research efforts in academic, clinical, and industrial settings have led to significant improvements in the current implementation of IPDT, and these studies have demonstrated the unique advantages of this modality for the treatment of solid tumors. It is envisioned that further randomized prospective clinical trials and treatment optimization will enable a wide acceptance of IPDT in the clinical community and inclusion in SoC guidelines for well-defined clinical indications.

CONCLUSIONS

The minimally invasive nature of this treatment modality combined with the relatively mild side effects makes IPDT a compelling alternative option for treatment in a number of clinical applications. The adaptability of this technique provides many opportunities to both optimize and personalize the treatment.

Autophagy Regulation and Photodynamic Therapy: Insights to Improve Outcomes of Cancer Treatment

Cancer is considered an age-related disease that, over the next 10 years, will become the most prevalent health problem worldwide. Although cancer therapy has remarkably improved in the last few decades, novel treatment concepts are needed to defeat this disease. Photodynamic Therapy (PDT) signalize a pathway to treat and manage several types of cancer. Over the past three decades, new light sources and photosensitizers (PS) have been developed to be applied in PDT. Nevertheless, there is a lack of knowledge to explain the main biochemical routes needed to trigger regulated cell death mechanisms, affecting, considerably, the scope of the PDT. Although autophagy modulation is being raised as an interesting strategy to be used in cancer therapy, the main aspects referring to the autophagy role over cell succumbing PDT-photoinduced damage remain elusive. Several reports emphasize cytoprotective autophagy, as an ultimate attempt of cells to cope with the photo-induced stress and to survive. Moreover, other underlying molecular mechanisms that evoke PDT-resistance of tumor cells were considered. We reviewed the paradigm about the PDT-regulated cell death mechanisms that involve autophagic impairment or boosted activation. To comprise the autophagy-targeted PDT-protocols to treat cancer, it was underlined those that alleviate or intensify PDT-resistance of tumor cells. Thereby, this review provides insights into the mechanisms by which PDT can be used to modulate autophagy and emphasizes how this field represents a promising therapeutic strategy for cancer treatment.