Inhibition of LNCaP prostate cancer cells by means of androgen receptor antisense oligonucleotides

Abstract

Currently available methods for treatment of human prostatic carcinoma aim to inactivate the androgen receptor (AR) by androgen deprivation or blockade with anti-androgens. Failure of endocrine therapy and tumor progression is characterized by androgenindependent growth despite high levels of AR expression in metastatic disease. We inhibited AR expression in LNCaP prostate tumor cells by using antisense AR oligodeoxynucleotides (ODNs) and explored whether antisense AR treatment would be conceivable as a therapy for advanced prostate cancer. Among the various AR antisense ODNs tested, a 15-base ODN targeting the CAG repeats encoding the poly-glutamine region of the AR (as750/15) was found to be most effective. Treatment of LNCaP cells with as750/15 reduced AR expression to ϳ2% within 24 hours compared with mock-treated controls. AR down-regulation resulted in significant cell growth inhibition, strongly reduced secretion of the androgen-regulated prostate-specific antigen, reduction of epidermal growth factor receptor expression, and an increase in apoptotic cells. Mis-sense and mismatched control ODNs had no or only slight effects. Antisense inhibition was also very efficient in LNCaP-abl cells, a subline established after long-term androgen ablation of LNCaP cells, resulting in inhibition of AR expression and cell proliferation that was similar to that seen for parental LNCaP cells. This study shows that inhibition of AR expression by antisense AR ODNs may be a promising new approach for treatment of advanced human prostate cancer. Cancer Gene Therapy (2000) 7, 997-1007

The diverse and contrasting effects of using human prostate cancer cell lines to study androgen receptor roles in prostate cancer

“…Similar results were also reported by Liao et al [14] and Haag et al [15]. Eder et al [16] inhibited AR expression in LNCaP cells using antisense AR oligodeoxynucleotides and reduced AR expression to approximately 2% of normal levels within 24 h. They found that down-regulating AR significantly inhibited LNCaP cell growth, strongly reduced secretion of the androgen-regulated prostatespecific antigen and increased the level of cell apoptosis [16]. Eder et al [17] further investigated the effects of AR knockdown on prostate tumor growth in vivo using a mouse xenograft model.…”

Androgen receptor level controlled by a suppressor complex lost in an androgen-independent prostate cancer cell line

“…Consequently, restoration of normal AR expression/function may prove to be an effective mean of treatment in this stage of the disease. This concept is supported by recent observations that downregulation of AR expression by means of AR antisense oligos, or disruption of AR function via direct injection of AR antibody into cells, produced significant inhibition of proliferation of the refractory PC cells, and induced apoptosis (Eder et al, 2000;Zegarra-Moro et al, 2002).…”

Fulvestrant (ICI 182,780) down-regulates androgen receptor expression and diminishes androgenic responses in LNCaP human prostate cancer cells

“…Because the AR is clearly a critical factor in prostate cancer and AIPC development, down-regulating or reducing the AR would be a very useful strategy for treating ARdependent prostate cancer (8). Thus far, the techniques that have been used to down-regulate the AR include antisense oligonucleotides (34,35), ribozyme treatments (36, 37), AR dominant negatives (38), and small interfering RNAs (39 -41). Reducing AR levels by these various means results in the inhibition of prostate cancer cell growth and PSA expression, while the small interfering RNA knockdown of AR expression also leads to significant apoptotic cell death in androgen-sensitive and AIPC cells (39 -41).…”