INCIDENCE OF SKELETAL COMPLICATIONS IN PATIENTS WITH BONE METASTATIC PROSTATE CANCER AND HORMONE REFRACTORY DISEASE: PREDICTIVE ROLE OF BONE RESORPTION AND FORMATION MARKERS EVALUATED AT BASELINE:

Abscisic acid signaling through LANCL2 and PPARγ induces activation of p38MAPK resulting in dormancy of prostate cancer metastatic cells

Prostate cancer (PCa) is one the most common malignancies in men. The high incidence of bone metastasis years after primary therapy suggests that disseminated tumor cells must become dormant, but maintain their ability to proliferate in the bone marrow. Abscisic acid (ABA) is a stress response molecule best known for its regulation of seed germination, stomal opening, root shoot growth and other stress responses in plants. ABA is also synthesized by mammalian cells and has been linked to human disease. The aim of the present study was to examine the role of ABA in regulating tumor dormancy via signaling through lanthionine synthetase C‑like protein 2 (LANCL2) and peroxisome proliferator activated receptor γ (PPARγ) receptors. ABA signaling in human PCa cell lines was studied using targeted gene knockdown (KD), western blotting, quantitative PCR, cell proliferation, migration, invasion and soft agar assays, as well as co‑culture assays with bone marrow stromal cells. The data demonstrated that ABA signaling increased the expression of p21, p27 and p16, while inhibiting viability, migration, invasion and colony size in a reversable manner without toxicity. ABA also induced p38MAPK activation and NR2F1 signaling. Targeted gene KD of LANCL2 and PPARγ abrogated the cellular responses to ABA. Taken together, these data demonstrate that ABA may induce dormancy in PCa cell lines through LANCL2 and PPARγ signaling, and suggest novel targets to manage metastatic PCa growth.

Skeletal complications and the use of bisphosphonates in metastatic prostate cancer

Metastatic prostate cancer represents an incurable progression of the disease that accounts for the vast majority of disease related mortality and is associated with significant skeletal morbidity with events including bone pain, fractures and spinal cord compression. This article provides an overview of the bone disease in this patient group, with a specific focus on the role of bisphosphonate use, in addressing quality of life issues. Key clinical trial data relating to bisphosphonates is presented and discussed, culminating in key management guidelines.

Bisphosphonates in the management of metastatic prostate cancer

Prostate cancer (PCA) frequently metastasizes to the bones, and skeletal metastases represent the most common cause of morbidity in advanced PCA. Besides the development of skeletal events due to metastases, patients with PCA are at higher risk for benign osseous complications, such as osteoporosis and fractures. Bisphosphonates (BPs) have emerged as an integral part of the management of skeletal disease related to PCA. Currently available data support their routine use to prevent androgen-deprivation-induced osteoporosis and its secondary complications. Dosing at 3-month intervals is appropriate; further studies will have to demonstrate the efficacy of annual dosing. In men with already established bone metastases, BPs might be helpful in preventing skeletal-related events in patients who do not respond to alternative therapies and are at high risk for bone fractures or spinal cord compression. In patients with hormone-refractory prostate cancer, BPs might be administered for analgesic purposes. Prospective randomized trials will have to explore the clinical role of BPs in the prevention of bone metastases following local therapy with curative intent in men at high risk for PCA recurrences.