Distinct patterns of endothelin axis expression in primary prostate cancer

Area of Science:

• Oncology
• Molecular Biology
• Biochemistry

Background:

• Emerging evidence implicates the endothelin-1 (ET-1) system, including endothelin A (ET(A)) and B (ET(B)) receptors and neutral endopeptidase (NEP), in prostate cancer progression.
• Clinical trials indicate that ET axis blockade can delay disease progression in advanced prostate cancer patients.

Purpose of the Study:

• To investigate the expression patterns of ET(A), ET(B), and NEP in prostate cancer, prostatic intraepithelial neoplasia, and normal adjacent tissues.
• To analyze the correlation between these protein levels and prostate cancer progression, including pathologic stage, grade, and recurrence.

Main Methods:

• Immunohistochemistry was used to quantify ET(A), ET(B), and NEP expression in 120 prostate cancer specimens.
• In situ hybridization confirmed immunohistochemistry findings in a subset of samples.
• Protein levels were correlated with clinical parameters such as stage, grade, and prostate-specific antigen recurrence.

Main Results:

• High ET(A) expression was observed in 72% of adenocarcinoma specimens and significantly correlated with increased pathologic stage and grade.
• ET(B) and NEP levels were decreased in adenocarcinoma compared to normal and pre-neoplastic tissues, but did not correlate with tumor stage or grade.
• Elevated ET(A) levels in primary tumors were associated with prostate-specific antigen recurrence.
• Patients with high ET(A) and low ET(B)/NEP expression showed a significantly shorter interval to PSA progression.

Conclusions:

• Two distinct ET(A) expression patterns in primary prostate cancer are suggested, with higher expression linked to more aggressive disease.
• Identifying patients based on these ET(A) expression patterns could optimize response to ET axis blockade therapies.
• This approach may enhance treatment outcomes for prostate cancer patients.