Serum prolactin level as a predictive factor for abiraterone response in patients with metastatic castration-resistant prostate cancer.

BACKGROUND: To investigate the prognostic value and potential therapeutic target of the baseline serum hormones in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with abiraterone. METHODS: This retrospective study was performed in patients with mCRPC receiving abiraterone acetate (AA) from July 2016 to September 2020. Patients who had serum hormone tests within 2 weeks before AA treatment were included. Univariate analysis and Cox regression were performed to evaluate the correlation of sex hormones with progression-free survival (PFS) and overall survival (OS). Prolactin (PRL) expression in the clinical specimens was evaluated by immunohistochemistry. Bone metastases were quantified by automated Bone Scan Index (aBSI). RESULTS: The study included 61 patients with a median follow-up of 19.0 months. Patients with lower baseline PRL levels (median) responded better to AA than those with higher baseline PRL levels as indicated by prostate-specific antigen (PSA) reduction (PSA90, 66.7% vs. 25.8%, p = 0.001), PFS (19.6 vs. 7.9 months), and OS (52.8 vs. 19.2 months). Cox regression adjusted for clinical factors also confirmed that baseline PRL level was an independent predictive factor for PFS (hazard ratio = 1.096, p = 0.007). Prostatic PRL expression increased as the disease progressed. PRL expression was also detected in biopsy samples from bone metastasis but not in normal bone tissue, and the serum PRL levels were positively correlated with aBSIs (r = 0.28, p = 0.037). CONCLUSIONS: Serum PRL levels are predictive of response to AA in patients with mCRPC. Serum PRL levels are positively correlated with the volume of metastatic bone disease.

PRL-mediated STAT5B/ARRB2 pathway promotes the progression of prostate cancer through the activation of MAPK signaling.

Previous study showed that higher expression of prolactin (PRL) was found in CRPC samples compared with hormone-naive prostate cancer (HNPC) and benign prostatic hyperplasia (BPH) samples. We further investigate the function of PRL in prostate cancer (PCa) and explored its downstream effects. We found heterogeneous expression of the PRLR in clinical prostate samples. The VCaP and 22Rv1 cells exhibited PRLR expression. Among the downstream proteins, STAT5B was the dominant subtype in clinical samples and cell lines. Human recombinant PRL stimulation of PCa cells with PRLR expression resulted in increased phosphorylation of STAT5B(pSTAT5B) and progression of PCa in vitro and in vivo, and STAT5B knockdown can suppress the malignant behavior of PCa. To understand the mechanism further, we performed Bioinformatic analysis, ChIP qPCR, and luciferase reporter gene assay. The results revealed that ARRB2 was the transcription target gene of STAT5B, and higher expression of ARRB2 was related to higher aggression and poorer prognosis of PCa. Additionally, Gene set enrichment analysis indicated that higher expression of ARRB2 was significantly enriched in the MAPK signaling pathway. Immunohistochemistry (IHC) demonstrated elevated pSTAT5B, ARRB2, and pERK1/2 expression levels in CRPC tissues compared to HNPC and BPH. Mechanically, ARRB2 enhanced the activation of the MAPK pathway by binding to ERK1/2, thereby promoting the phosphorylation of ERK1/2 (pERK1/2). In conclusion, our study demonstrated that PRL stimulation can promote the progression of PCa through STAT5B/ARRB2 pathway and activation of MAPK signaling, which can be suppressed by intervention targeting STAT5B. Blockade of the STAT5B can be a potential therapeutic target for PCa.

Perineural Invasion as a Risk Factor For Soft Tissue Progression in Patients With Metastatic Castration-Resistant Prostate Cancer After Abiraterone Resistance.

BACKGROUND: Prostate cancer presents with soft tissue progression (STP) is highly aggressive. We analyzed the risk factor for STP in patients with metastatic castration-resistant prostate cancer (mCRPC) who developed abiraterone acetate (AA) resistance. METHODS: This retrospective study included patients with mCRPC who received AA between February 2018 and July 2022. STP was defined as recurrent lesions in situ, multiple regional lymph node metastases (mLNM), or visceral metastases. Clinical features of patients with STP were analyzed, and risk factors for STP were further investigated. RESULTS: Sixty-three patients (mean age, 75.0 years; median follow-up time, 22.3 months) were included in this study. Twenty-three patients (36.5%) presented STP during follow up, the overall survival (OS) after STP was 4.6 months. The serum neuron-specific enolase (NSE) were significantly elevated in patients with STP. Biopsies for 8 patients with STP showed neuroendocrine prostate cancer (NEPC, n = 5) was the major pathological types. Further analysis showed that perineural invasion (PNI) in primary tumor were the independent risk factors (HR = 3.145, P = 0.020) for STP, and PNI was related to the aggressiveness of tumor. Patients with PNI showed shorter castration-resistant progression free survival (median, 23.73 months vs. 25.59 months) and STP progression free survival (median, 19.7 months vs. not reached) compared with patients without PNI. CONCLUSIONS: STP showed extremely poor prognoses in patients with mCRPC after AA resistance, NEPC is the main pathological type of STP, and PNI in primary tumor was an independent risk factor for STP and indicated poor prognosis of prostate cancer.

The clinical efficacy and limitations of dutasteride-regulated abiraterone metabolism in abiraterone-resistant patients: a prospective single-arm clinical trial in Chinese patients.

Background: The steroidal metabolism of abiraterone has been proposed to be involved in abiraterone resistance and limited approaches are available for abiraterone-resistant patients. Dutasteride regulates abiraterone metabolism in patients and might enhance the clinical efficacy of abiraterone. However, the function of dutasteride to overcome abiraterone resistance has not been investigated in clinic. Here we investigated the clinical efficacy and limitations of dutasteride in patients with abiraterone-resistant prostate cancer. Methods: Abiraterone-resistant patients with metastatic castration-resistant prostate cancer (mCRPC) were enrolled in this single-arm, open-label study, patients were treated with dutasteride (0.5 mg/day), abiraterone (1,000 mg/day), and prednisone (5 mg twice daily), prostate-specific antigen (PSA) was tested monthly. The primary objective was PSA response, and the secondary objectives were to assess symptom relief and safety. Kaplan-Meier analysis was used to assess the PSA progression free survival (PSA-PFS) of patients. Results: Twenty-two patients (median age: 75 years) were enrolled, and 19 patients completed the treatment. After a median treatment of 4.0 months, 7 (37%) patients showed a slight PSA reduction (-2% to -32%), and the median PSA-PFS was 2.0 months (1-7 months). No significant improvement was observed in Eastern Cooperative Oncology Group (ECOG) performance status. Bone pain was relieved in 6 patients after 1 month of treatment, but the improvement was not significant. No grade 3 or grade 4 adverse events were observed. Conclusions: The combination of dutasteride and abiraterone showed a mild effect in patients with abiraterone-resistant. The small sample size was the limitation of this study.

Inhibiting 3ßHSD1 to eliminate the oncogenic effects of progesterone in prostate cancer.

Prostate cancer continuously progresses following deprivation of circulating androgens originating from the testis and adrenal glands, indicating the existence of oncometabolites beyond androgens. In this study, mass-spectrometry-based screening of clinical specimens and a retrospective analysis on the clinical data of prostate cancer patients indicate the potential oncogenic effects of progesterone in patients. High doses of progesterone activate canonical and non-canonical androgen receptor (AR) target genes. Physiological levels of progesterone facilitate cell proliferation via GATA2. Inhibitors of 3ß-hydroxysteroid dehydrogenase 1 (3ßHSD1) has been discovered and shown to suppress the generation of progesterone, eliminating its transient and accumulating oncogenic effects. An increase in progesterone is associated with poor clinical outcomes in patients and may be used as a predictive biomarker. Overall, we demonstrate that progesterone acts as an oncogenic hormone in prostate cancer, and strategies to eliminate its oncogenic effects may benefit prostate cancer patients.