Prevention and management of prostate cancer chemotherapy complications

Expression of multidrug resistance proteins in prostate cancer is related with cell sensitivity to chemotherapeutic drugs

BACKGROUND

Multidrug resistance (MDR) proteins have been associated with the lack of chemotherapy response. Expression of these proteins has been described in the prostate, but there is no information about their role in the chemotherapy response of prostate cancer (PC). We studied the gene and protein expression of MDR proteins in primary cell cultures from PC tumors and PC cell lines, their relationship with chemotherapy and their effects on cell survival.

METHODS

Primary cell cultures from PC were obtained from samples provided by our Institutional Hospital. Cell lines LNCaP, PC3, and DU145 were also examined. Cells were treated during 72 hr with several chemotherapeutic drugs. Protein and mRNA expressions of P-glycoprotein (P-Gp), MRP1 and LRP, before and after drug treatment, were evaluated by RT-PCR and Western blot analyses. The effect on cell survival was evaluated by proliferation assays (MTT), and cell cycle and apoptosis by flow cytometry.

RESULTS

Primary PC cultures exhibited higher MDR protein expression and lower drug sensitivity than cell lines, in which P-Gp was not detected. Docetaxel and mitoxantrone displayed the highest apoptotic effect. Exposure to chemotherapeutic drugs increased apoptosis, cell cycle arrest, and MDR expression. Long-term treatment with doxorubicin diminished apoptosis elicited by all drugs examined in this study, suggesting a cross-resistance phenomenon.

CONCLUSIONS

Low chemotherapy response observed in PC primary cultures could be explained, in part, by the high levels of MDR proteins (intrinsic MDR phenotype), and also, by their over-expression induced after long-term exposure to drugs (acquired MDR phenotype), which increase treatment resistance. Prostate 69: 1448-1459, 2009. (c) 2009 Wiley-Liss, Inc.

Opportunities for disease state management in prostate cancer

In this paper, we examine how the management of prostate cancer lends itself to a disease state management (DSM)-based approach, and propose a framework that emphasizes the patient-provider-caregiver triad in managing the long-term implications of the condition. There is often no clearly superior approach to the management of patients with prostate cancer (eg, watchful waiting and hormonal therapy), and each option entails different trade-offs in quality of life. Ideally, the physician and patient discuss the options, issues, and patient preferences for treatment through the shared decision-making process. A family caregiver such as the spouse of the patient is often involved in the treatment decision and in the long-term management of the cancer experience. In order to develop a DSM program supporting both patient and caregiver, educational, psychosocial, and health care system support needs should be tailored to each phase of cancer treatment/management. To embrace the unique aspects of prostate cancer management, the proposed framework emphasizes communication among the patient-caregiver-provider triad, inclusion of family caregivers in the program, cancer phase-specific support, and psychosocial services as a basis for implementation and evaluation of a DSM program in prostate cancer.

Patupilone (epothilone B, EPO906) inhibits growth and metastasis of experimental prostate tumors in vivo

BACKGROUND

Microtubule agents appear promising for the treatment of prostate cancer. Patupilone (epothilone B), a highly potent non-taxane microtubule stabilizing agent, was evaluated in models of androgen-independent prostate cancer.

METHODS

Patupilone was administered to athymic mice bearing human prostate cancer xenografts (subcutaneous DU 145 and PC-3M, orthotopic PC-3M).

RESULTS

One 4 mg/kg patupilone administration produced transient regression of DU 145 tumors, while two weekly administrations of 2.5 mg/kg produced stable disease followed by protracted regression, however with more pronounced body weight loss. Taxol (15 mg/kg every other day) weakly inhibited tumor growth, but with less body weight loss. Patupilone (5 mg/kg) produced protracted growth inhibition of subcutaneous PC-3M tumors, with transient body weight loss. In mice with orthotopic PC-3M tumors, 4 or 5 mg/kg/week patupilone impaired primary tumor growth, abrogated metastases and enhanced survival, with only transient body weight loss.

CONCLUSIONS

These data suggest that patupilone holds promise for prostate cancer treatment.