TPPP3 Overexpression Suppresses Nasopharyngeal Carcinoma Progression and Promotes Immune Microenvironment Remodeling...

Objectives: Nasopharyngeal carcinoma (NPC) arises in an immune-suppressive milieu that frequently undermines treatment efficacy. TPPP3 has been implicated as a negative regulator of NPC aggressiveness, yet its relevance to immune modulation or chaperone networks remains poorly defined. We therefore sought to determine how TPPP3 shapes the NPC immune landscape and to identify its interacting protein partners. Methods: Public single-cell RNA-sequencing datasets from head and neck squamous cell carcinoma and nasopharyngeal carcinoma were analyzed using R. HK-1 and C666-1 cells stably overexpressing TPPP3 were established. These cells were used to construct humanized xenograft tumor models, with intratumoral immune cell infiltration evaluated by immunohistochemistry. In vitro, the same cells and their controls were indirectly co-cultured with peripheral blood mononuclear cells. Cellular lysates from TPPP3-overexpressing cells were subjected to immunoprecipitation-mass spectrometry and immunofluorescence staining, which identified HSPA8 as a TPPP3-interacting protein. Three groups-control, TPPP3-overexpressing, and TPPP3-overexpressing plus the HSPA8 inhibitor VER155008-were then compared in wound healing, colony formation, cell-cycle, and xenograft assays, with immunohistochemical staining for Ki67, TPPP3, and CD3 performed on tumor sections. Results: TPPP3 transcripts were barely detectable across most tumor cell subsets but showed preferential enrichment in NPC epithelial clusters. Enforced TPPP3 expression curtailed xenograft outgrowth while increasing intratumoral abundance of CD3⁺ T cells, CD8⁺ T cells, and CD11c⁺ dendritic cells. Pharmacological blockade of HSPA8 with VER155008 further enhanced TPPP3-driven suppression of migration, clonogenicity, and tumor expansion, and also altered cell-cycle progression while boosting CD3⁺ T-cell accumulation within grafts. Conclusions: These findings suggest a functional association between TPPP3 and HSPA8 that may contribute to tumor growth suppression and immune microenvironment remodeling in NPC. Pharmacological disruption of HSPA8-dependent proteostasis enhanced TPPP3-associated antitumor activity in both in vitro and in vivo models, indicating that this chaperone pathway represents a candidate mechanism worthy of further mechanistic investigation and therapeutic exploration.