Background

Human papillomavirus (HPV) infection and related diseases are difficult clinical challenges. The efficacy of 5-aminolevulinic acid photodynamic therapy (ALA-PDT) in treating condyloma acuminata is remarkable, with high virus clearance and low recurrence rates. Podophyllotoxin (POD) is the first-line drug with a significant therapeutic effect on condyloma acuminata. However, no studies have determined whether POD-combined ALA-PDT improves high-risk (HR)-HPV-infected cell killing. We aimed to investigate whether POD-combined ALA-PDT could promote HPV-infected cell death more effectively than the single treatment and explore the underlying mechanism.

Methods

In HeLa and SiHa cells, flow cytometry, EdU assay and LDH release test were used to detect apoptosis, cell proliferation change and necrosis, respectively. To investigate whether the combined therapy might activate apoptosis and induce endoplasmic reticulum (ER) stress, flow cytometry was used to determine intracellular levels of ROS and calcium, western blotting was used to determine the expression of related proteins. Mitochondrial membrane depolarisation was detected by JC-1 assay. Immunofluorescence staining and western blotting were used to detect the activation of autophagy.

Results

POD-combined ALA-PDT inhibited the proliferation and promoted apoptosis and necrosis more effectively than the single treatment at the same intensity and concentration. The activation of the caspase-dependent apoptosis pathway, ER stress, and autophagy were more substantial in POD-combined ALA-PDT than with single treatments.

Conclusion

POD-combined ALA-PDT effectively promoted cell death through several pathways in HeLa and SiHa cells. This combination might be a promising therapeutic strategy for the HR-HPV infection.