A combination of photodynamic therapy and chemotherapy displays a differential cytotoxic effect on human metastatic melanoma cells

Nrf2-Mediated Antioxidant Response and Drug Efflux Transporters Upregulation as Possible Mechanisms of Resistance in Photodynamic Therapy of Cancers

Photodynamic therapy (PDT) is a groundbreaking approach involving the induction of cytotoxic reactive oxygen species (ROS) within tumors through visible light activation of photosensitizers (PS) in the presence of molecular oxygen. This innovative therapy has demonstrated success in treating various cancers. While PDT proves highly effective in most solid tumors, there are indications that certain cancers exhibit resistance, and some initially responsive cancers may develop intrinsic or acquired resistance to PDT. The molecular mechanisms underlying this resistance are not fully understood. Recent evidence suggests that, akin to other traditional cancer treatments, the activation of survival pathways, such as the KEAP1/Nrf2 signaling pathway, is emerging as an important mechanism of post-PDT resistance in many cancers. This article explores the dual role of Nrf2, highlighting evidence linking aberrant Nrf2 expression to treatment resistance across a range of cancers. Additionally, it delves into the specific role of Nrf2 in the context of photodynamic therapy for cancers, emphasizing evidence that suggests Nrf2-mediated upregulation of antioxidant responses and induction of drug efflux transporters are potential mechanisms of resistance to PDT in diverse cancer types. Therefore, understanding the specific role(s) of Nrf2 in PDT resistance may pave the way for the development of more effective cancer treatments using PDT.

Development of Novel Bimodal Agents Based on Near-Infrared BODIPY-Conjugated Hoechst Derivatives for Combined Use in Auger Electron and Photodynamic Cancer Therapy

Auger electron therapy and photodynamic therapy (PDT) have attracted attention as powerful anticancer modalities. Herein, we report the development of novel bimodal agents for Auger electron therapy and PDT, and their application to combination therapy. [125I]NBH-1/NBH-1 and [125I]NBH-2/NBH-2, composing Hoechst and iodostyryl-BODIPY, were synthesized and evaluated regarding their usefulness as bimodal agents. [125I]NBH-1 showed significantly higher nuclear uptake than [125I]NBH-2 and radioactivity-dependent cytotoxicity induced by Auger electrons. In addition, NBH-1 exhibited photoinduced cytotoxicity. Combination therapy using [125I]NBH-1 and NBH-1 with light irradiation induced a superior cytotoxicity to these treatments alone. In tumor-bearing mice injected with NBH-1 or [125I]NBH-1/NBH-1 under light irradiation, significant tumor growth inhibition was observed compared with that of the control group. Especially, [125I]NBH-1/NBH-1 under light irradiation showed the strongest therapeutic effects among all treatments. These results suggest that [125I]NBH-1/NBH-1 is a potent bimodal agent for Auger therapy and PDT and that combination therapy using [125I]NBH-1 and NBH-1 shows enhanced therapeutic efficacy.

Targeting ferroptosis in melanoma: cancer therapeutics

Melanoma is an aggressive kind of skin cancer; its rate has risen rapidly over the past few decades. Melanoma reports for only about 1% of skin cancers but leads to a high majority of skin cancer deaths. Thus, new useful therapeutic approaches are currently required, to state effective treatments to consistently enhance the overall survival rate of melanoma patients. Ferroptosis is a recently identified cell death process, which is different from autophagy, apoptosis, necrosis, and pyroptosis in terms of biochemistry, genetics, and morphology which plays an important role in cancer treatment. Ferroptosis happens mostly by accumulating iron and lipid peroxides in the cell. Recently, studies have revealed that ferroptosis has a key role in the tumor's progression. Especially, inducing ferroptosis in cells can inhibit the tumor cells' growth, leading to back warding tumorigenesis. Here, we outline the ferroptosis characteristics from its basic role in melanoma cancer and mention its possible applications in melanoma cancer treatment. Video Abstract.

Melanoma spheroid-containing artificial dermis as an alternative approach to in vivo models

Melanoma spheroid-loaded 3D skin models allow for the study of crucial tumor characteristics and factors at a superior level because the neoplastic cells are integrated into essential human skin components, permitting tumor-skin model communication. Herein, we designed a melanoma-containing artificial dermis by inserting multicellular tumor spheroids from the metastatic phase of WM 1617 melanoma cells into an artificial dermis. We cultured multicellular melanoma spheroids by hanging drop method (250 cells per drop) with a size of 420 μm in diameter after incubation for 14 days. These spheroids were integrated into the dermal equivalents that had been previously preparedwith a type-I collagen matrix and healthy fibroblasts. The melanoma spheroid cells invaded and proliferated in the artificial dermis. Spheroids treated with a 1.0 μmol/L aluminum chloride phthalocyanine nanoemulsion in the absence of light showed high cell viability. In contrast, under irradiation with visible red light (660 nm) at 25 J/cm2, melanoma cells were killed and the healthy tissue was preserved, indicating that photodynamic therapy is effective in such a model. Therefore, the 3D skin melanoma model has potential to promote research in full-thickness skin model targeting optimized preclinical assays.

Nanoparticle-Based Combination Therapy for Melanoma

Melanoma is a cutaneous carcinoma, and its incidence is rapidly increasing with every year. The treatment options for melanoma have been comprehensively studied. Conventional treatment methods (e.g., radiotherapy, chemotherapy and photodynamic therapy) with surgical removal inevitably cause serious complications; moreover, resistance is common. Nanoparticles (NPs) combined with conventional methods are new and promising options to treat melanoma, and many combinations have been achieving good success. Due to their physical and biological features, NPs can help target intended melanoma cells more efficiently with less damage. This creates new hope for a better treatment strategy for melanoma with minimum damage and maximum efficacy.

Recent Advances in Near Infrared Upconverting Nanomaterials for Targeted Photodynamic Therapy of Cancer

Photodynamic therapy (PDT) is a well-established treatment of cancer that uses the toxic reactive oxygen species, including singlet oxygen (1O2), generated by photosensitiser drugs following irradiation of a specific wavelength to destroy the cancerous cells and tumours. Visible light is commonly used as the excitation source in PDT, which is not ideal for cancer treatment due to its reduced tissue penetration, and thus inefficiency to treat deep-lying tumours. Additionally, these wavelengths exhibit elevated autofluorescence background from the biological tissues which hinders optical biomedical imaging. An alternative to UV-Vis irradiation is the use of near infrared (NIR) excitation for PDT. This can be achieved using upconverting nanoparticles (UCNPs) functionalised with photosensitiser (PS) drugs where UCNPs can be used as an indirect excitation source for the activation of PS drugs yielding to the production of singlet 1O2 following NIR excitation. The use of nanoparticles for PDT is also beneficial due to their tumour targeting capability, either passively via the enhanced permeability and retention (EPR) effect or actively via stimuli-responsive targeting and ligand-mediated targeting (ie. using recognition units that can bind specific receptors only present or overexpressed on tumour cells). Here, we review recent advances in NIR upconverting nanomaterials for PDT of cancer with a clear distinction between those reported nanoparticles that could potentially target the tumour due to accumulation via the EPR effect (passive targeting) and nanoparticle-based systems that contain targeting agents with the aim of actively target the tumour via a molecular recognition process.

Melanoma therapeutics: a literature review

Melanoma is a relentless type of skin cancer which involves myriad signaling pathways which regulate many cellular processes. This makes melanoma difficult to treat, especially when identified late. At present, therapeutics include chemotherapy, surgical resection, biochemotherapy, immunotherapy, photodynamic and targeted approaches. These interventions are usually administered as either a single-drug or in combination, based on tumor location, stage, and patients' overall health condition. However, treatment efficacy generally decreases as patients develop treatment resistance. Genetic profiling of melanocytes and the discovery of novel molecular factors involved in the pathogenesis of melanoma have helped to identify new therapeutic targets. In this literature review, we examine several newly approved therapies, and briefly describe several therapies being assessed for melanoma. The goal is to provide a comprehensive overview of recent developments and to consider future directions in the field of melanoma.

ROS Pleiotropy in Melanoma and Local Therapy with Physical Modalities

Metabolic energy production naturally generates unwanted products such as reactive oxygen species (ROS), causing oxidative damage. Oxidative damage has been linked to several pathologies, including diabetes, premature aging, neurodegenerative diseases, and cancer. ROS were therefore originally anticipated as an imperative evil, a product of an imperfect system. More recently, however, the role of ROS in signaling and tumor treatment is increasingly acknowledged. This review addresses the main types, sources, and pathways of ROS in melanoma by linking their pleiotropic roles in antioxidant and oxidant regulation, hypoxia, metabolism, and cell death. In addition, the implications of ROS in various physical therapy modalities targeting melanoma, such as radiotherapy, electrochemotherapy, hyperthermia, photodynamic therapy, and medical gas plasma, are also discussed. By including ROS in the main picture of melanoma skin cancer and as an integral part of cancer therapies, a greater understanding of melanoma cell biology is presented, which ultimately may elucidate additional clues on targeting therapy resistance of this most deadly form of skin cancer.

Antibody-Based Targeted Interventions for the Diagnosis and Treatment of Skin Cancers

BACKGROUND

Cutaneous malignancies most commonly arise from skin epidermal cells. These cancers may rapidly progress from benign to a metastatic phase. Surgical resection represents the gold standard therapeutic treatment of non-metastatic skin cancer while chemo- and/or radiotherapy are often used against metastatic tumors. However, these therapeutic treatments are limited by the development of resistance and toxic side effects, resulting from the passive accumulation of cytotoxic drugs within healthy cells.

OBJECTIVE

This review aims to elucidate how the use of monoclonal Antibodies (mAbs) targeting specific Tumor Associated Antigens (TAAs) is paving the way to improved treatment. These mAbs are used as therapeutic or diagnostic carriers that can specifically deliver cytotoxic molecules, fluorophores or radiolabels to cancer cells that overexpress specific target antigens.

RESULTS

mAbs raised against TAAs are widely in use for e.g. differential diagnosis, prognosis and therapy of skin cancers. Antibody-Drug Conjugates (ADCs) particularly show remarkable potential. The safest ADCs reported to date use non-toxic photo-activatable Photosensitizers (PSs), allowing targeted Photodynamic Therapy (PDT) resulting in targeted delivery of PS into cancer cells and selective killing after light activation without harming the normal cell population. The use of near-infrared-emitting PSs enables both diagnostic and therapeutic applications upon light activation at the specific wavelengths.

CONCLUSION

Antibody-based approaches are presenting an array of opportunities to complement and improve current methods employed for skin cancer diagnosis and treatment.

Novel Multifunctional Ascorbic Triazole Derivatives for Amyloidogenic Pathway Inhibition, Anti-Inflammation, and Neuroprotection

Alzheimer's disease (AD) is a common neurodegenerative disorder. The number of patients with AD is projected to reach 152 million by 2050. Donepezil, rivastigmine, galantamine, and memantine are the only four drugs currently approved by the United States Food and Drug Administration for AD treatment. However, these drugs can only alleviate AD symptoms. Thus, this research focuses on the discovery of novel lead compounds that possess multitarget regulation of AD etiopathology relating to amyloid cascade. The ascorbic acid structure has been designated as a core functional domain due to several characteristics, including antioxidant activities, amyloid aggregation inhibition, and the ability to be transported to the brain and neurons. Multifunctional ascorbic derivatives were synthesized by copper (I)-catalyzed azide-alkyne cycloaddition reaction (click chemistry). The in vitro and cell-based assays showed that compounds 2c and 5c exhibited prominent multifunctional activities as beta-secretase 1 inhibitors, amyloid aggregation inhibitors, and antioxidant, neuroprotectant, and anti-inflammatory agents. Significant changes in activities promoting neuroprotection and anti-inflammation were observed at a considerably low concentration at a nanomolar level. Moreover, an in silico study showed that compounds 2c and 5c were capable of being permeated across the blood-brain barrier by sodium-dependent vitamin C transporter-2.

Berberine-photodynamic therapy sensitizes melanoma cells to cisplatin-induced apoptosis through ROS-mediated P38 MAPK pathways

The clinical use of cisplatin are limited due to its drug resistance. Thus, it is urgent to find effective combination therapy that sensitizes tumor cells to this drug. The combined chemo-photodynamic therapy could increase anti-tumor efficacy while also reduce the side effects of cisplatin. Berberine is an isoquinoline alkaloid, which has been reported to show high photosensitizing activity. In this study, we have examined the effect of a combination of cisplatin and berberine-PDT in cisplatin-resistant melanoma cells. The cytotoxic effects of berberine-PDT alone or in combination with cisplatin were tested by MTT assays. We then examined the subcellular localization of berberine with confocal fluorescence microscopy. The percentage of apoptotic cells, the mitochondrial membrane potential (Δψm) and reactive oxygen species (ROS) generation assessed using flow cytometry analysis. Western blotting used in this study to determine the expression levels of MAPK signaling pathways and apoptosis-related proteins. Experimental data revealed that the mode of cell death is the caspase-dependent mitochondrial apoptotic pathways. Excessive accumulation of ROS played a key role in this process, which is confirmed by alleviation of cytotoxicity upon pretreatment with NAC. Furthermore, we found that the combined treatment activated MAPK signaling pathway. The inhibition of p38 MAPK by pretreating with SB203580 block the combined treatment-induced apoptotic cell death. In conclusion, berberine-PDT could be used as a chemo-sensitizer by promoting cell death through activation of a ROS/p38/caspase cascade.

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.

Effect of aqueous extracts of Ficus vogeliana Miq and Tieghemella africana Pierre in 7,12-Dimethylbenz(a)anthracene -induced skin cancer in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Skin cancer is the most common form of cancer responsible for considerable morbidity and mortality. Tieghemella africana and Ficus vogeliana are used in traditional medicine to treat cancers.

AIM OF THE STUDY

Therefore, the aim of this study was to investigate the antioxidant, antiangiogenic and anti-tumor activities of these plant extracts.

MATERIALS AND METHODS

To achieve it, phytochemical screening, antioxidant activity and antiangiogenic activity were assessed. Thereafter, the anti-tumor activity was determined using skin tumorigenesis induced by 7,12-dimethylbenz[a]anthracene.

RESULTS

The phytochemical result analysis showed that both plant extracts were rich in polyphenols, alkaloids and terpene compounds and possessed good antioxidant activity based on DPPH radical scavenging (IC₅₀ = 9.70 μg/mL and 4.60 μg/mL and AAI values of 5.20 and 10.88) and strong total antioxidant capacity (115.44 VtCE (mg)/g of dry plant extract and 87.37 VtCE (mg)/g of dry plant extract, respectively). Additionally, both plant extracts possessed antiangiogenic activities (IC₅₀ = 53.43 μg/mL and 92.68 μg/mL, respectively), which correlated with significant antitumor activities when using 35 mg/kg (65.02% and 77.54%) and 70 mg/kg of extracts (81.07% and 88.18%).

CONCLUSIONS

In summary, this study illustrates the promising usage of Tieghemella africana and Ficus vogeliana plant extracts in treating skin cancer. However, further characterization of the extracts must be performed to isolate the most active anticancer compound.

Antibody-Based Immunotherapy: Alternative Approaches for the Treatment of Metastatic Melanoma

Melanoma is the least common form of skin cancer and is associated with the highest mortality. Where melanoma is mostly unresponsive to conventional therapies (e.g., chemotherapy), BRAF inhibitor treatment has shown improved therapeutic outcomes. Photodynamic therapy (PDT) relies on a light-activated compound to produce death-inducing amounts of reactive oxygen species (ROS). Their capacity to selectively accumulate in tumor cells has been confirmed in melanoma treatment with some encouraging results. However, this treatment approach has not reached clinical fruition for melanoma due to major limitations associated with the development of resistance and subsequent side effects. These adverse effects might be bypassed by immunotherapy in the form of antibody–drug conjugates (ADCs) relying on the ability of monoclonal antibodies (mAbs) to target specific tumor-associated antigens (TAAs) and to be used as carriers to specifically deliver cytotoxic warheads into corresponding tumor cells. Of late, the continued refinement of ADC therapeutic efficacy has given rise to photoimmunotherapy (PIT) (a light-sensitive compound conjugated to mAbs), which by virtue of requiring light activation only exerts its toxic effect on light-irradiated cells. As such, this review aims to highlight the potential clinical benefits of various armed antibody-based immunotherapies, including PDT, as alternative approaches for the treatment of metastatic melanoma.

Desensitization of metastatic melanoma cells to therapeutic treatment through repeated exposure to dacarbazine

Aberrant anti-cancer drug efflux mediated by membrane protein ABC transporters (ABCB5 and ABCG2) is thought to characterize melanoma heterogeneous chemoresistant populations, presumed to have unlimited proliferative and self-renewal abilities. Therefore, this study primarily aimed to investigate whether continuous exposure of melanoma cells to dacarbazine (DTIC) chemotherapeutic drug enriches cultures with therapy resistant cells. Thereafter, we sought to determine whether combining the genotoxic activity of DTIC with the oxidative insults of hypericin activated photodynamic therapy (HYP-PDT) could synergized to kill heterogenous chemoresistant melanoma populations. This study revealed that DTIC resistant (UCT Mel-1DTICR2) melanoma cells were less sensitive to all therapies than parental melanoma cells (UCT Mel-1), yet combination therapy was the most efficient. At the exception of DTIC treatment, both HYP-PDT and the combination therapy were effective in significantly reducing the Hoechst non-effluxing dye melanoma main populations (MP) compared to their side population (SP) counterparts. Likewise, HYP-PDT and combination therapy significantly reduced self-renewal capacity, increased expression of ABCB5 and ABCG2 transporters and differentially induced cell cycle arrest and cell death (apoptosis or necrosis) depending on the melanoma MP cell type. Collectively, combination therapy could synergistically reduce melanoma proliferative and clonogenic potential. However, further research is needed to decipher the cellular mechanisms underlying this resistance which would enable combination therapy to reach therapeutic fruition.

Hydrogen-Peroxide-Responsive Protein Biomimetic Nanoparticles for Photothermal-Photodynamic Combination Therapy of Melanoma

BACKGROUND AND OBJECTIVES

Recently, there has been a rapid increase in the incidences of melanoma, which represents a serious threat to human health. Generally, tumor-microenvironment-responsive nanoparticle-based photothermal-photodynamic combination therapy (PTT-PDT) is characterized by intratumoral response and tumor targeting. In this study, we designed and synthesized hydrogen-peroxide-responsive protein biomimetic nanoparticles (MnO₂ -ICG@BSA) for the treatment of melanoma.

STUDY DESIGN/MATERIALS AND METHODS

Briefly, MnO₂ -ICG@BSA was prepared using a mild protein synthesis method by loading indocyanine green (ICG) into a bovine serum albumin-manganese dioxide complex (MnO₂ @BSA); next, its characteristics were determined. In addition, in vitro biocompatibility and antitumor efficacy were assessed using the classic cell counting kit-8 assay. Moreover, in vivo high-frequency ultrasound and thermal imaging were used to evaluate the oxygen-production capacity and photothermal conversion effect of MnO₂ -ICG@BSA at the tumor site, and Singlet Oxygen Sensor Green (SOSG) was used to measure singlet oxygen levels in the tumor. The antitumor efficacy was assessed based on relative tumor size, bodyweight, survival curves, and hematoxylin and eosin staining.

RESULTS

The results showed that MnO₂ -ICG@BSA has a high photothermal conversion efficiency, a strong singlet oxygen-generation ability, and high photothermal stability. In addition, in vitro PTT-PDT experiments showed that MnO₂ -ICG@BSA has a significant inhibitory effect on the proliferation of B16F10 melanoma cells. Meanwhile, in vivo experiments showed that MnO₂ -ICG@BSA has a significant inhibitory effect on melanoma in mice. Preliminary toxicity studies indicated that MnO₂ -ICG@BSA exhibits low toxicity.

CONCLUSION

From the results, we can conclude that MnO₂ -ICG@BSA could be used in PTT-PDT to treat melanoma, making it a good candidate material for PTT-PDT. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Susceptibility and Resistance Mechanisms During Photodynamic Therapy of Melanoma

Melanoma is the most aggressive malignant skin tumor and arises from melanocytes. The resistance of melanoma cells to various treatments results in rapid tumor growth and high mortality. As a local therapeutic modality, photodynamic therapy has been successfully applied for clinical treatment of skin diseases. Photodynamic therapy is a relatively new treatment method for various types of malignant tumors in humans and, compared to conventional treatment methods, has fewer side effects, and is more accurate and non-invasive. Although several in vivo and in vitro studies have shown encouraging results regarding the potential benefits of photodynamic therapy as an adjuvant treatment for melanoma, its clinical application remains limited owing to its relative inefficiency. This review article discusses the use of photodynamic therapy in melanoma treatment as well as the latest progress made in deciphering the mechanism of tolerance. Lastly, potential targets are identified that may improve photodynamic therapy against melanoma cells.

Chemo-photodynamic therapy by pulmonary delivery of gefitinib nanoparticles and 5-aminolevulinic acid for treatment of primary lung cancer of rats

Lung cancer is a severe disease with high mortality. Chemotherapy is one major treatment for lung cancer. However, systemic chemotherapeutics usually distribute throughout the body without specific lung distribution so that serious side effects are unavoidable. Photodynamic therapy (PDT) is occasionally used for lung cancer treatment but photosensitizers are also systemically administered and the bronchoscopic intervention under anesthesia may hurt lung tissues. Here, we combined inhaled chemotherapeutics and photosensitizers for chemo-photodynamic therapy (CPDT) of primary lung cancer of rats with external laser light irradiation. Gefitinib PLGA nanoparticles (GNPs) were prepared. The anti-cancer effects of GNPs and/or a common photosensitizer 5-aminolevulinic acid (5-ALA) were explored on A549 cells (adenocarcinomic human alveolar basal epithelial cells) and primary lung cancer rats after intratracheal administration. External light irradiation was applied due to its higher safety compared to internal light irradiation that may result in injuries after a laser optic fiber was intubated into the lung. The remarkable synergistic effect of CPDT was confirmed although the single therapies were also effective, where the high anti-lung cancer effects were shown and some typical lung cancer markers, including CD31, VEGF, NF-κB p65 and Bcl-2, significantly decreased. Moreover, the treatments attenuated inflammation with the downregulation of TNF-α. The combination of pulmonary drug delivery and chemo-photodynamic therapy is a promising strategy for treatment of lung cancer.

mRNA Therapies: New Hope in the Fight against Melanoma

Melanoma is a life-threatening disease caused by mutations in pigment-producing cells. Numerous treatments for melanoma have been approved in the past several decades; however, they often cause severe side effects and in most cases do not result in a complete cure. mRNA (messenger RNA) as a therapeutic agent provides a new avenue for melanoma treatment and several advantages over conventional treatments. The first mRNA drugs for melanoma treatment are currently in clinical trials, and approval of mRNA drugs by the Food and Drug Administration seems to be within reach. This new class of drugs can be readily adapted to other diseases, raising the hope of providing a new therapeutic option for various diseases.

Viral Vector-Based Melanoma Gene Therapy

Gene therapy applications of oncolytic viruses represent an attractive alternative for cancer treatment. A broad range of oncolytic viruses, including adenoviruses, adeno-associated viruses, alphaviruses, herpes simplex viruses, retroviruses, lentiviruses, rhabdoviruses, reoviruses, measles virus, Newcastle disease virus, picornaviruses and poxviruses, have been used in diverse preclinical and clinical studies for the treatment of various diseases, including colon, head-and-neck, prostate and breast cancer as well as squamous cell carcinoma and glioma. The majority of studies have focused on immunotherapy and several drugs based on viral vectors have been approved. However, gene therapy for malignant melanoma based on viral vectors has not been utilized to its full potential yet. This review represents a summary of the achievements of preclinical and clinical studies using viral vectors, with the focus on malignant melanoma.

The role of ABCG2 in modulating responses to anti-cancer photodynamic therapy

The ATP-binding cassette (ABC) superfamily G member 2 (ABCG2) transmembrane protein transporter is known for conferring resistance to treatment in cancers. Photodynamic therapy (PDT) is a promising anti-cancer method involving the use of light-activated photosensitisers to precisely induce oxidative stress and cell death in cancers. ABCG2 can efflux photosensitisers from out of cells, reducing the capacity of PDT and limiting the efficacy of treatment. Many studies have attempted to elucidate the relationship between the expression of ABCG2 in cancers, its effect on the cellular retention of photosensitisers and its impact on PDT. This review looks at the studies which investigate the effect of ABCG2 on a range of different photosensitisers in different pre-clinical models of cancer. This work also evaluates the approaches that are being investigated to address the role of ABCG2 in PDT with an outlook on potential clinical validation.

The Dark Side: Photosensitizer Prodrugs

Photodynamic therapy (PDT) and photodiagnosis (PD) are essential approaches in the field of biophotonics. Ideally, both modalities require the selective sensitization of the targeted disease in order to avoid undesired phenomena such as the destruction of healthy tissue, skin photosensitization, or mistaken diagnosis. To a large extent, the occurrence of these incidents can be attributed to “background” accumulation in non-target tissue. Therefore, an ideal photoactive compound should be optically silent in the absence of disease, but bright in its presence. Such requirements can be fulfilled using innovative prodrug strategies targeting disease-associated alterations. Here we will summarize the elaboration, characterization, and evaluation of approaches using polymeric photosensitizer prodrugs, nanoparticles, micelles, and porphysomes. Finally, we will discuss the use of 5-aminolevulinc acid and its derivatives that are selectively transformed in neoplastic cells into photoactive protoporphyrin IX.

Magnetic And pH Dual-Responsive Nanoparticles For Synergistic Drug-Resistant Breast Cancer Chemo/Photodynamic Therapy

BACKGROUND

Drug resistance is one of the prime reasons of chemotherapy failure in breast cancer and is also an important factor affecting prognosis.

PURPOSE

In this study, we constructed a functional magnetic mesoporous silica-based nanocomposite (MMSN) for breast cancer chemotherapy/photodynamic therapy.

METHODS

MMSN was characterized by scanning electron microscopy and transmission electron microscopy to observe the morphology. The size distribution and zeta potential of the MSNs were determined using Malvern Particle Size Analyzer. Anti-tumor activity in vitro was investigated by CCK-8 assay, flow cytometry and transwell experiment, and the anti-tumor activity in vivo was probed into by magnetic targeting, toxicity, and antitumor effects in breast cancer-bearing BABL/c nude mice.

RESULTS

The results showed that the release of doxorubicin in the nanocomposites was pH sensitive, and the cumulative release rate reached 80.53% at 60 h under acidic conditions. The nanocomposites had a high cellular uptake ability in MCF-7/ADR cells, and the IC50 value of the nanocomposites on MCF-7/ADR cells was 4.23 μg/mL, much smaller than that of free DOX (363.2 μg/mL). The nanocomposites could effectively reverse resistance and induce apoptosis of MCF-7/ADR cells. The blood biochemistry parameters and H&E staining results showed no serious adverse effects after treatment with the nanocomposites. Prussian blue staining showed that the nanocomposites were able to target tumor tissues in tumor-bearing mice under a magnetic field. The combined chemical/photodynamic therapy significantly inhibited tumor growth in vivo.

CONCLUSION

Nanocomposites with magnetic and pH dual-responsive performance has shown a promising platform for enhanced drug-resistant breast cancer treatment.

Synergistic effect of meta-tetra(hydroxyphenyl)chlorin-based photodynamic therapy followed by cisplatin on malignant Hep-2 cells

Purpose

Tumor drug resistance limits the response to chemotherapy. Interestingly, sequential combination therapy enhances the anticancer efficacy of drugs like cisplatin (CDDP) via synergistic effects. We assayed the synergistic effects of combined photodynamic therapy programmed death receptor-ligand 1 (PDT) and chemotherapy in malignant Hep-2 cells.

Methods

In the cultured Hep-2 cells, meta-tetra(hydroxyphenyl)chlorin (m-THPC) and CDDP were administered separately or in combination. The cellular viability and apoptosis were assessed, accompanied by measurement of the expression of Bax, Bcl-2, ATG-7, and LC3 (LC3-I and LC3-II). Additionally, nuclear chromatin changes, drug retention, and PD-L1 expression were further investigated following different treatments.

Results

The sequential treatment significantly diminished cell viability and induced cell apoptosis, in consistency with the usage of single therapeutic strategies, as reflected by an increase in Bax expression and decrease of Bcl-2 expression. Moreover, ATG-7 and LC3-II/LC3-I ratio were reduced after administration of the sequential treatment. Synergetic effect of nuclear chromatin configuration, negative effects of cellular drug retention, and a decrease in PD-L1 expression were observed following the sequential treatment.

Conclusion

The application of sequential treatment of PDT in combination with chemotherapy offers a promising therapeutic option for cancer treatment, by regulating the PD-L1 expression, autophagy, and non-mitochondrial pathways.

Applications of SNAP-tag technology in skin cancer therapy

BACKGROUND

Cancer treatment in the 21st century has seen immense advances in optical imaging and immunotherapy. Significant progress has been made in the bioengineering and production of immunoconjugates to achieve the goal of specifically targeting tumors.

DISCUSSION

In the 21st century, antibody drug conjugates (ADCs) have been the focus of immunotherapeutic strategies in cancer. ADCs combine the unique targeting of monoclonal antibodies (mAbs) with the cancer killing ability of cytotoxic drugs. However, due to random conjugation methods of drug to antibody, ADCs are associated with poor antigen specificity and low cytotoxicity, resulting in a drug to antibody ratio (DAR) >1. This means that the cytotoxic drugs in ADCs are conjugated randomly to antibodies, by cysteine or lysine residues. This generates heterogeneous ADC populations with 0 to 8 drugs per an antibody, each with distinct pharmacokinetic, efficacy, and toxicity properties. Additionally, heterogeneity is created not only by different antibody to ligand ratios but also by different sites of conjugation. Hence, much effort has been made to find and establish antibody conjugation strategies that enable us to better control stoichiometry and site-specificity. This includes utilizing protein self-labeling tags as fusion partners to the original protein. Site-specific conjugation is a significant characteristic of these engineered proteins. SNAP-tag is one such engineered self-labeling protein tag shown to have promising potential in cancer treatment. The SNAP-tag is fused to an antibody of choice and covalently reacts specifically in a 1:1 ratio with benzylguanine (BG) substrates, eg, fluorophores or photosensitizers, to target skin cancer. This makes SNAP-tag a versatile technique in optical imaging and photoimmunotherapy of skin cancer.

CONCLUSION

SNAP-tag technology has the potential to contribute greatly to a broad range of molecular oncological applications because it combines efficacious tumor targeting, minimized local and systemic toxicity, and noninvasive assessment of diagnostic/prognostic molecular biomarkers of cancer.

Melanoma treatment in review

Melanoma represents the most aggressive and the deadliest form of skin cancer. Current therapeutic approaches include surgical resection, chemotherapy, photodynamic therapy, immunotherapy, biochemotherapy, and targeted therapy. The therapeutic strategy can include single agents or combined therapies, depending on the patient’s health, stage, and location of the tumor. The efficiency of these treatments can be decreased due to the development of diverse resistance mechanisms. New therapeutic targets have emerged from studies of the genetic profile of melanocytes and from the identification of molecular factors involved in the pathogenesis of the malignant transformation. In this review, we aim to survey therapies approved and under evaluation for melanoma treatment and relevant research on the molecular mechanisms underlying melanomagenesis.