Subclinical photodynamic therapy treatment modifies the brain microenvironment and promotes glioma growth

Photosensitizers for Photodynamic Therapy of Brain Cancers-A Review

On average, there are about 300,000 new cases of brain cancer each year. Studies have shown that brain and central nervous system tumors are among the top ten causes of death. Due to the extent of this problem and the percentage of patients suffering from brain tumors, innovative therapeutic treatment methods are constantly being sought. One such innovative therapeutic method is photodynamic therapy (PDT). Photodynamic therapy is an alternative and unique technique widely used in dermatology and other fields of medicine for the treatment of oncological and nononcological lesions. Photodynamic therapy consists of the destruction of cancer cells and inducing inflammatory changes by using laser light of a specific wavelength in combination with the application of a photosensitizer. The most commonly used photosensitizers include 5-aminolevulinic acid for the enzymatic generation of protoporphyrin IX, Temoporfin-THPC, Photofrin, Hypericin and Talaporfin. This paper reviews the photosensitizers commonly used in photodynamic therapy for brain tumors. An overview of all three generations of photosensitizers is presented. Along with an indication of the limitations of the treatment of brain tumors, intraoperative photodynamic therapy and its possibilities are described as an alternative therapeutic method.

Photodynamic treatment modulates various GTPase and cellular signalling pathways in Tauopathy

The application of photo-excited dyes for treatment is known as photodynamic therapy (PDT). PDT is known to target GTPase proteins in cells, which are the key proteins of diverse signalling cascades which ultimately modulate cell proliferation and death. Cytoskeletal proteins play critical roles in maintaining cell integrity and cell division. Whereas, it was also observed that in neuronal cells PDT modulated actin and tubulin resulting in increased neurite growth and filopodia. Recent studies supported the role of PDT in dissolving the extracellular amyloid beta aggregates and intracellular Tau aggregates, which indicated the potential role of PDT in neurodegeneration. The advancement in the field of PDT led to its clinical approval in treatment of cancers, brain tumour, and dermatological acne. Although several question need to be answered for application of PDT in neuronal cells, but the primary studies gave a hint that it can emerge as potential therapy in neural cells.

Understanding the glioblastoma tumor biology to optimize photodynamic therapy: From molecular to cellular events

Photodynamic therapy (PDT) has recently gained attention as an alternative treatment of malignant gliomas. Glioblastoma (GBM) is the most prevalent within tumors of the central nervous system (CNS). Conventional treatments for this CNS tumor include surgery, radiation, and chemotherapy. Surgery is still being considered as the treatment of choice. Even so, the poor prognosis and/or recurrence of the disease after applying any of these treatments highlight the urgency of exploring new therapies and/or improving existing ones to achieve the definitive eradication of tumor masses and remaining cells. PDT is a therapeutic modality that involves the destruction of tumor cells by reactive oxygen species induced by light, which were previously treated with a photosensitizing agent. However, in recent years, its experimental application has expanded to other effects that could improve overall performance against GBM. In the current review, we revisit the main advances of PDT for GBM management and also, the recent mechanistic insights about cellular and molecular aspects related to tumoral resistance to PDT of GBM.

Photodynamic therapy for keratoacanthoma on the upper lip

BACKGROUND

Keratoacanthoma (KA) is a cutaneous neoplasm, which is similar to squamous cell carcinoma (SCC) clinically, cytologically, and histopathologically. Surgical resection is the first choice for treating KA, but it may be impractical when a KA is located in a cosmetically sensitive area.

OBSERVATION

We describe a patient with a nodule on the right upper lip. We performed a surgical biopsy to obtain a histopathological diagnosis. Specimen analysis revealed a diagnosis of KA. As the tumor was located in the upper lip, a direct resection may require a flap to reconstruct the lip shape; instead, a noninvasive field approach using photodynamic therapy (PDT) was initiated. After five sessions of treatment, the lesion disappeared, and there was no scar.

CONCLUSIONS

Although there is no consensus on using PDT to treat KA, we provide a case report on the effective use of PDT in the treatment of KAs. PDT can be an alternative treatment option when KA is located in a particular anatomic site.

Synthesis andin vitroanticancer activity of water-soluble cationic pyridylporphyrins and their metallocomplexes

Tetrapyrrolic compounds such as porphyrins are known to be prospective chemotherapeutics and photosensitizers for cancer treatment and diagnosis. In this work, water-soluble, meso-substituted cationic pyridyl-porphyrins and their metallocomplexes bearing various central metal atoms ( Ag , Zn , Co , and Fe ) in the porphine ring and various functional groups (allyl, oxyethyl, butyl, and methallyl) at the nitrogen atom in the pyridine ring were synthesized and characterized by1H and13C NMR and UV-visible spectroscopy. Cytotoxic and photodynamic activities of new porphyrins and their metal derivatives were investigated in vitro (KCL-22 cancer cell line of human chronic myeloid leukemia). The cytotoxicity of porphyrins was shown to be dependent on the presence and type of the central metal atom in the porphine ring. Ag -derivatives were more cytotoxic than Co −, Zn −, and Fe − metallocomplexes. The porphyrins bearing allyl-functional groups were evidenced to be more cytotoxic than those which included butyl-, oxyethyl-, and methallyl-groups. The change of nitrogen position in the pyridine ring of Ag -metalloporphyrins from 3(3-N-pyridylporphyrins) to 4(4-N-pyridylporphyrins) induced an increase in the cytotoxic activity of metallocomplexes. All synthesized Ag-metalloporphyrins, except, the oxyethyl-containing one were more cytotoxic than cisplatin. Allyl containing free porphyrin and its Zn -metallocomplex had higher phototoxicity than Ag −, Co −, and Fe -metalloporphyrins. The results obtained can be useful for further investigation of new porphyrins as potential chemotherapeutics and photosensitizers.

Induction of immune mediators in glioma and prostate cancer cells by non-lethal photodynamic therapy

Background

Photodynamic therapy (PDT) uses the combination of photosensitizing drugs and harmless light to cause selective damage to tumor cells. PDT is therefore an option for focal therapy of localized disease or for otherwise unresectable tumors. In addition, there is increasing evidence that PDT can induce systemic anti-tumor immunity, supporting control of tumor cells, which were not eliminated by the primary treatment. However, the effect of non-lethal PDT on the behavior and malignant potential of tumor cells surviving PDT is molecularly not well defined.

Methodology/Principal Findings

Here we have evaluated changes in the transcriptome of human glioblastoma (U87, U373) and human (PC-3, DU145) and murine prostate cancer cells (TRAMP-C1, TRAMP-C2) after non-lethal PDT in vitro and in vivo using oligonucleotide microarray analyses. We found that the overall response was similar between the different cell lines and photosensitizers both in vitro and in vivo. The most prominently upregulated genes encoded proteins that belong to pathways activated by cellular stress or are involved in cell cycle arrest. This response was similar to the rescue response of tumor cells following high-dose PDT. In contrast, tumor cells dealing with non-lethal PDT were found to significantly upregulate a number of immune genes, which included the chemokine genes CXCL2, CXCL3 and IL8/CXCL8 as well as the genes for IL6 and its receptor IL6R, which can stimulate proinflammatory reactions, while IL6 and IL6R can also enhance tumor growth.

Conclusions

Our results indicate that PDT can support anti-tumor immune responses and is, therefore, a rational therapy even if tumor cells cannot be completely eliminated by primary phototoxic mechanisms alone. However, non-lethal PDT can also stimulate tumor growth-promoting autocrine loops, as seen by the upregulation of IL6 and its receptor. Thus the efficacy of PDT to treat tumors may be improved by controlling unwanted and potentially deleterious growth-stimulatory pathways.

Non-invasive quantification of brain tumor-induced astrogliosis

Background

CNS injury including stroke, infection, and tumor growth lead to astrogliosis, a process that involves upregulation of glial fibrillary acidic protein (GFAP) in astrocytes. However, the kinetics of astrogliosis that is related to these insults (i.e. tumor) is largely unknown.

Results

Using transgenic mice expressing firefly luciferase under the regulation of the GFAP promoter (GFAP-luc), we developed a model system to monitor astrogliosis upon tumor growth in a rapid, non-invasive manner. A biphasic induction of astrogliosis was observed in our xenograft model in which an early phase of activation of GFAP was associated with inflammatory response followed by a secondary, long-term upregulation of GFAP. These animals reveal GFAP activation with kinetics that is in parallel with tumor growth. Furthermore, a strong correlation between astrogliosis and tumor size was observed.

Conclusions

Our results suggest that non-invasive, quantitative bioluminescent imaging using GFAP-luc reporter animal is a useful tool to monitor temporal-spatial kinetics of host-mediated astrogliosis that is associated with glioma and metastatic brain tumor growth.

Sensitization of cerebral tissue in nude mice with photodynamic therapy induces ADAM17/TACE and promotes glioma cell invasion

In the present study, we tested the hypothesis that a mild cerebral tissue injury promotes subsequent glioma invasion via activation of the ADAM17-EGFR-PI3K-Akt pathway. Mild injury was induced by photodynamic therapy (PDT), which employs tissue-penetrating laser light exposure following systemic administration of a tumor-localizing photosensitizer. Athymic nude mice were treated with sublethal PDT (80 J/cm2 with 2 mg/kg Photofrin). Hypoxic stress and ADAM17-EGFR-PI3K-Akt were measured using Western blot and immunostaining. Additional groups with/without pro-sublethal PDT were subsequently implanted with U87 glioma tumor cell. Tumor invasion and ADAM17-EGFR-PI3K-Akt pathway in tumor area were measured. After a sublethal dose of PDT, HIF-1alpha expression was increased by a factor of three in PDT-treated normal brain tissue compared to contralateral control brain tissue. PDT-treated brain tissue exhibited a significant increase in ADAM17, p-EGFR, p-Akt expression compared to non-treated tissue. ADAM17 positive area significantly increased from 1.78% to 10.89%. The percentage of p-EGFR and p-Akt positive cells significantly increased from 9.50% and 14.50% to 21.31% and 32.29%, respectively, PDT treatment significantly increased subsequent implanted U87 glioma cell invasion by 3.68-fold and increased ADAM17, EGFR, p-EGFR, Akt, p-Akt expression by 178%, 43.9%, 152.7%, 89.6%,and 164.2%, respectively, compared to control group. Our data showed that a sublethal sensitization of cerebral tissue with PDT significantly increased U87 cell invasion in nude mice, and that glioma cell invasion is highly correlated with activation of the ADAM17-EGFR-PI3K-Akt pathway (r=0.928, 0.775, 0.870, 0.872, and 0.883, respectively), most likely via HIF-1alpha.