Simultaneous disturbance of NHE1 and LOXL2 decreases tumorigenicity of head and neck squamous cell carcinoma

Auris Nasus Larynx. 2024 Jun;51(3):472-480. doi: 10.1016/j.anl.2024.01.006. Epub 2024 Mar 22.

Abstract

Objective: Although there have been brilliant advancements in the practical application of therapies targeting immune checkpoints, achieving success in targeting the microenvironment remains elusive. In this study, we aimed to address this gap by focusing on Na+ / H+ exchanger 1 (NHE1) and Lysyl Oxidase Like 2 (LOXL2), which are upregulated in head and neck squamous cell carcinoma (HNSCC) cells.

Methods: The malignancy of a metastatic human HNSCC cell line was assessed in a mouse tongue cancer xenograft model by knocking down (KD) NHE1, responsible for regulating intracellular pH, and LOXL2, responsible for extracellular matrix (ECM) reorganization via cross-linking of ECM proteins. In addition to assessing changes in PD-L1 levels and collagen accumulation following knockdown, the functional status of the PD-L1 / PD-1 immune checkpoint was examined through co-culture with NK92MI, a PD-1 positive phagocytic human Natural Killer (NK) cell line.

Results: The tumorigenic potential of each single KD cell line was similar to that of the control cells, whereas the potential was attenuated in cells with simultaneous KD of both factors (double knockdown [dKD]). Additionally, we observed decreased PD-L1 levels in NHE1 KD cells and compromised collagen accumulation in LOXL2 KD and dKD cells. NK92MI cells exhibited phagocytic activity toward HNSCC cells in co-culture, and the number of remaining dKD cells after co-culture was the lowest in comparison to the control and single KD cells.

Conclusion: This study demonstrated the possibility of achieving efficient anti-tumor effects by simultaneously disturbing multiple factors involved in the modification of the tumor microenvironment.

Keywords: Extracellular matrix; Head and neck squamous cellcarcinoma; Lysyl oxidase like 2; Na(+)/H(+) exchanger 1; Primary xenograft lesion; Tumor microenvironment.

MeSH terms

  • Amino Acid Oxidoreductases* / genetics
  • Amino Acid Oxidoreductases* / metabolism
  • Animals
  • B7-H1 Antigen / genetics
  • B7-H1 Antigen / metabolism
  • Carcinogenesis / genetics
  • Cell Line, Tumor
  • Collagen / metabolism
  • Gene Knockdown Techniques
  • Head and Neck Neoplasms* / genetics
  • Head and Neck Neoplasms* / metabolism
  • Head and Neck Neoplasms* / pathology
  • Humans
  • Killer Cells, Natural
  • Mice
  • Programmed Cell Death 1 Receptor / genetics
  • Programmed Cell Death 1 Receptor / metabolism
  • Sodium-Hydrogen Exchanger 1* / genetics
  • Sodium-Hydrogen Exchanger 1* / metabolism
  • Squamous Cell Carcinoma of Head and Neck* / genetics
  • Squamous Cell Carcinoma of Head and Neck* / metabolism
  • Squamous Cell Carcinoma of Head and Neck* / pathology
  • Tongue Neoplasms* / genetics
  • Tongue Neoplasms* / metabolism
  • Tongue Neoplasms* / pathology
  • Tumor Microenvironment

Substances

  • Sodium-Hydrogen Exchanger 1
  • Amino Acid Oxidoreductases
  • SLC9A1 protein, human
  • B7-H1 Antigen
  • LOXL2 protein, human
  • Collagen
  • Programmed Cell Death 1 Receptor