Antagonism between HTRA3 and TGFβ1 Contributes to Metastasis in Non-Small Cell Lung Cancer

Area of Science:

• Oncology
• Molecular Biology
• Cancer Research

Background:

• High temperature requirement A3 (HTRA3) is a tumor suppressor, but its role in non-small cell lung cancer (NSCLC) is unclear.
• Tumor metastasis and epithelial-mesenchymal transition (EMT) are critical processes in NSCLC progression.

Purpose of the Study:

• To elucidate the molecular functions of HTRA3 in NSCLC.
• To investigate the relationship between HTRA3 and TGFβ1 in NSCLC.
• To understand the impact of HTRA3 on NSCLC prognosis and treatment response.

Main Methods:

• Correlation analysis of HTRA3 and TGFβ1 levels in NSCLC tumor tissues.
• In vitro studies using NSCLC cell lines to assess the effects of TGFβ1 on HTRA3 expression and EMT.
• Mechanistic studies involving c-Jun binding to the HTRA3 promoter and assessment of HTRA3-L overexpression effects.

Main Results:

• Decreased HTRA3 levels negatively correlate with elevated TGFβ1 in metastatic NSCLC.
• High HTRA3 expression is associated with better prognosis, independent of TGFβ1.
• TGFβ1 downregulates HTRA3, particularly the long isoform, during EMT induction.
• c-Jun, upregulated by TGFβ1, directly inhibits HTRA3-L transcription.
• HTRA3-L overexpression suppresses TGFβ1-mediated invasion and metastasis and sensitizes cells to anti-PD-L1 therapy.

Conclusions:

• HTRA3 acts as a brake on TGFβ1's oncogenic effects in early-stage NSCLC, inhibiting metastasis.
• In advanced NSCLC, reduced HTRA3 allows TGFβ1 to promote EMT.
• HTRA3 is a novel mediator suppressing TGFβ1-driven oncogenic effects in lung cancer.