Down-regulation of RB1 and TP53 as potential predicting biomarkers for castration-resistant prostate cancer (CRPC): Indonesian retrospective cohort study

Introduction: Androgen deprivation therapy (ADT) has remained the first line strategy for treatment of advanced
prostate cancers. Despite the profound efficacy of ADT in preventing clinical remission, 30–50% of advanced
prostate cancer will develop resistance to hormonal deprivation therapy. This study aimed to evaluate the potential
role of RB1 and TP53 expressions as biomarkers for predicting time to castration-resistant prostate cancer
(CRPC).
Methods: The clinical and pathological data of patients with prostate cancer were collected retrospectively from
Dr. Sardjito General Hospital, Yogyakarta. Between 2015 and 2019, a total of 36 patients who received castration
were included. Expressions of mRNA of RB1 and TP53 from primary tumors were quantified using quantitative
Real Time Polymerase Chain Reaction (qRT-PCR).
Results: The expressions of mRNA of RB1 and TP53 increased in prostate cancer tissues compared to hyperplastic
prostates and significantly downregulated in metastatic prostate cancers (p < 0.001). Lower mRNA TP53
expression correlated with shorter time to CRPC among patients treated with ADT (p = 0.006). In addition,
stratified analysis showed that lower mRNA RB1 expression was significantly associated with shorter CRPC both
in metastatic (p = 0.017) and non-metastatic (p = 0.001) prostate cancer patients.
Conclusions: Low expression of mRNA of RB1 and TP53 has been shown to be a potential marker of shorter time
to develop CRPC in patients with advanced stages of prostate cancer treated with ADT. Meanwhile, ISUP score
>4 were not shown predictive value on time to CRPC.