Successful treatment of non-melanoma skin cancer in three patients with Xeroderma Pigmentosum by modified ALA-PDT

Tea polyphenols nanoparticles integrated with microneedles multifunctionally boost 5-aminolevulinic acid photodynamic therapy for skin cancer

5-aminolevulinic acid photodynamic therapy (ALA-PDT) is an emerging therapeutic strategy for skin cancer due to its noninvasiveness and high spatiotemporal selectivity. However, poor skin penetration, poor intratumoral delivery, the instability of aqueous ALA, and the tumor's inherent hypoxia microenvironment are major hurdles hindering the efficacy of ALA-PDT. Herein, we aim to address these challenges by using microneedles (MNs) to assist in delivering nanoparticles based on natural polymeric tea polyphenols (TP NPs) to self-assemble and load ALA (ALA@TP NPs). The TP NPs specifically increase cellular uptake of ALA by A375 and A431 cells and reduce mitochondrial membrane potential. Subsequently, the photosensitizer protoporphyrin IX derived from ALA accumulates in the tumor cells in a dose-dependent manner with TP NPs, generating reactive oxygen species to promote apoptosis and necrosis of A375 and A431 cells. Interestingly, TP NPs can ameliorate the tumor's inherent hypoxia microenvironment and rapid oxygen consumption during PDT by inhibiting hypoxia inducible factor-1α, thereby boosting reactive oxygen species (ROS) generation and enhancing ALA-PDT efficacy through a positive feedback loop. After ALA@TP NPs are loaded into MNs to fabricate ALA@TP NPs@MNs, the MNs enhance skin penetration and storage stability of ALA. Importantly, they exhibit remarkable antitumor efficacy in A375-induced melanoma and A431-induced squamous cell carcinoma with a reduced dose of ALA and reverse hypoxia in vivo. This study provides a facile and novel strategy that integrates MNs and green NPs of TP for addressing the bottlenecks of ALA-PDT and enhancing the ALA-PDT efficacy against skin cancers for future clinical translation.

Modified 5-aminolevulinic acid photodynamic therapy induces cutaneous squamous cell carcinoma cell pyroptosis via the JNK signaling pathway

Modified 5-aminolevulinic acid photodynamic therapy (M-PDT) is a novel therapeutic modality for cutaneous squamous cell carcinoma (cSCC) that is reported to be effective and well tolerated. However, the mechanisms underlying its antitumor effects are not fully understood. In this research, we investigated the effects of M-PDT on pyroptosis, a form of programmed cell death characterized by cell swelling, ruptures of cell membrane, and inflammatory cytokine release, in two human cSCC cell lines, SCL-1 and HSC-5. We found that M-PDT triggered pyroptosis in a dose-dependent manner, as evidenced by increased lactate dehydrogenase release, propidium iodide staining, and expression of pyroptosis-related proteins, such as NLR family pyrin domain containing 3 (NLRP3), N-terminal of gasdermin D (N-GSDMD), cleaved caspase-1, and mature interleukin 1 beta (IL-1B) in both cell lines. This process was inhibited by treatment with MCC950, an NLRP3-specific inhibitor, suggesting the involvement of the NLRP3 inflammasome in M-PDT-induced pyroptosis. We also demonstrated that M-PDT activated c-Jun N-terminal kinase (JNK) signaling, which is required for pyroptosis induction, as treatment with SP600125, a JNK inhibitor, suppressed the expression of pyroptosis-related proteins after M-PDT. JNK activation enhanced M-PDT-induced pyroptosis, highlighting the significance of the JNK pathway in M-PDT. Moreover, M-PDT increased intracellular reactive oxygen species (ROS) levels, which are responsible for JNK activation and pyroptosis induction. In summary, our results revealed that M-PDT triggers pyroptosis through ROS-mediated JNK activation and subsequent NLRP3 inflammasome activation in cSCC cells, providing a better understanding of the molecular mechanism of M-PDT and promoting its clinical application.

Non-Surgical Therapeutic Strategies for Non-Melanoma Skin Cancers

OPINION STATEMENT

Non-melanoma skin cancer (NMSC) is a globally prevalent skin disease, with basal cell carcinoma and squamous cell carcinoma accounting for 99% of NMSC cases. While surgical excision is the most common approach, numerous non-surgical therapies have rapidly advanced in recent years. In cases of low-risk NMSC, alongside surgical excision, priority should be given to physical therapy and photodynamic therapy. Physical therapy modalities, exemplified by electrodessication and curettage, emerge as safe and efficacious alternatives. In juxtaposition, photodynamic therapy, albeit relatively more costly, assumes preference for patients exhibiting heightened cosmetic concerns owing to the scarring risks inherent to physical therapy and surgical excision. Notably, the combination of curettage and photodynamic therapy has exhibited remarkable efficacy in the treatment of nodular basal cell carcinoma. Additionally, for elderly patients who may be intolerant to stimulation, modified photodynamic therapy offers an almost painless option. When surgery is unavoidable, photodynamic therapy can be a valuable adjunct, allowing for a more conservative surgical approach, either before or after the procedure. Radiotherapy holds a prominent role in comprehensive treatment strategies, especially for patients ineligible for surgical intervention or those with lesions precluding further surgical measures. In cases of NMSC exhibiting perineural invasion or lymphovascular involvement, adjunctive radiotherapy is advised; however, potential adverse effects necessitate careful consideration. For advanced NMSC cases where surgery and physical therapy fall short, immunotherapy provide viable solutions. Systemic therapy employing Hedgehog pathway inhibitors can be considered for patients with distant metastatic basal cell carcinoma, despite its low incidence, or individuals with locally advanced lesions who are not surgical candidates, or those encountering recurrences after resection and radiotherapy. However, close monitoring of disease progression and adverse reactions is crucial. In this evolving landscape of NMSC treatment, personalized and multidisciplinary approaches are key, ensuring optimal outcomes while prioritizing patient safety and satisfaction.