D47 and SIGLEC15 Immune Checkpoint Genes Expression and Apoptotic Pathway Activation Following Photodynamic Therapy with Zinc Phthalocyanine in the B-CPAP Thyroid Cancer Cell Line

Golnaz  Fallah; Mehrdad  Pashazadeh; Abolfazl  Jafari-Sales; Habib  Tajalli; Seyedeh Samaneh  Shahriar-Oskouei

doi:10.18502/jabs.v16i2.20873

Golnaz Fallah Department of Genetics, Ta.C., Islamic Azad University, Tabriz, Iran
Mehrdad Pashazadeh Infectious Diseases Research Center, TaMS.C., Islamic Azad University, Tabriz, Iran
Abolfazl Jafari-Sales Infectious Diseases Research Center, TaMS.C., Islamic Azad University, Tabriz, Iran
Habib Tajalli Biophotonics Research Center, Ta.C., Islamic Azad University, Tabriz, Iran
Seyedeh Samaneh Shahriar-Oskouei Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran

DOI: https://doi.org/10.18502/jabs.v16i2.20873

Keywords: Thyroid cancer, Photodynamic therapy, Zinc phthalocyanine, Immune checkpoints, Apoptosis

Abstract

Background & Objectives: Thyroid cancer is one of the most prevalent endocrine malignancies.Photodynamic therapy is an emerging minimally invasive therapeutic modality that employs aphotosensitizer in conjunction with light irradiation to induce targeted cytotoxicity. The presentstudy was designed to evaluate the effects of zinc phthalocyanine-mediated photodynamictherapy on the expression of immune checkpoint genes CD47 and SIGLEC15, as well as keygenes involved in apoptotic pathways, in papillary thyroid cancer cells.

Materials & Methods: The human papillary thyroid cancer cell line B-CPAP was exposedto various concentrations of zinc phthalocyanine and subsequently irradiated using a675 nm diode laser at a fluence of 24 J/cm². Cellular viability, reflecting mitochondrialmetabolic activity, was assessed using the MTT assay. The relative mRNA expressionlevels of CD47, SIGLEC15, Caspase-3, Caspase-9 and Bcl-2 genes were quantified usingquantitative real-time polymerase chain reaction.

Results: Zinc phthalocyanine-mediated photodynamic therapy markedly reduced the viabilityof B-CPAP cells. The treatment activated the intrinsic apoptotic pathway, as demonstrated by thesignificant upregulation of Caspase-3 and Caspase-9 transcripts alongside the downregulation ofBcl-2 expression. In addition, a statistically significant reduction in the mRNA expression levels ofthe immune checkpoint molecules CD47 and SIGLEC15 was observed following treatment.

Conclusion: The findings of this study provide novel evidence that zinc phthalocyanine-mediated photodynamic therapy simultaneously induces apoptosis while downregulatingthe critical immune checkpoints CD47 and SIGLEC15 in thyroid cancer cells. This dualmechanism of action underscores the therapeutic potential of photodynamic therapy as aneffective strategy for enhancing antitumor efficacy through both direct cytotoxic effectsand the potential mitigation of immune evasion.