Korean J Urol.  2006 May;47(5):548-552. 10.4111/kju.2006.47.5.548.

Alterations in Calcium-Activated Potassium Channel Expressions in Human Prostate Cancer

• Kim DY
• Yang EK
• Kim JW

• KMID: 2294143
• DOI: http://doi.org/10.4111/kju.2006.47.5.548

Abstract

PURPOSE
Recent studies have shown that potassium (K+) and sodium channels are involved in prostate cell growth. However, a great many of the studies have been done in prostate cancer cell lines and there are only scant studies on prostate cancer and benign prostatic hypertrophy (BPH) tissue. The present study was aimed to evaluate the alterations of the calcium-activated K+ channel (KCa) expression in prostate cancer, and to compare them with the expression profiles in human BPH tissue to understand their potential role in the progression of prostate cancer.
MATERIALS AND METHODS
The prostate tissues obtained from radical prostatectomy (n=10) and transurethral resection of the prostate (n=18) were quickly frozen in liquid nitrogen for the RNA measurements. The protein and mRNA levels of the KCa subtypes and connexins were measured by performing immunoblot analysis and reverse-transcription polymerase chain reaction, respectively.
RESULTS
The mRNA levels of type 2 (SK2) and type 3 (SK3) small-conductance and large-conductance (BK) KCas in the prostate cancer tissues were decreased more than 50% compared with those in the BPH samples. In addition, the BK and SK2 protein levels in prostate cancer were also significantly lower than those in the BPH. As reported previously, the connexin 26 and 43 transcript signals in the prostate cancer were significantly reduced compared with those in the BPH samples.
CONCLUSIONS
These results suggest that the impaired expression of KCas may have a role in tumor progression via aberrant and uncontrolled prostate cell growth.

Keyword

Prostate cancer; Large-conductance calcium-activated potassium channels; Small-conductance calcium-activated potassium channels

MeSH Terms

Cell Line
Connexins
Humans*
Large-Conductance Calcium-Activated Potassium Channels
Nitrogen
Polymerase Chain Reaction
Potassium
Potassium Channels, Calcium-Activated*
Prostate*
Prostatectomy
Prostatic Hyperplasia
Prostatic Neoplasms*
RNA
RNA, Messenger
Small-Conductance Calcium-Activated Potassium Channels
Sodium Channels
Connexins
Large-Conductance Calcium-Activated Potassium Channels
Nitrogen
Potassium
Potassium Channels, Calcium-Activated
RNA
RNA, Messenger
Small-Conductance Calcium-Activated Potassium Channels
Sodium Channels

Figure

• 

  Fig. 1 Representative examples (upper panel) and densitometric analyses (lower panel) of the polymerase chain reaction (PCR) products for BK, IK, SK2 and SK3 are corrected with the β-actin in each sample. The values are expressed in arbitrary densitometric units (A.D.U.) as mean±SEM of the human prostate tissue with either benign prostatic hypertrophy (BPH) or prostate cancer (CaP). *p<0.05 and †p<0.01 compared to BPH (Mann-Whitney test). BK, IK and SK denote large-, intermediate-, and small-conductance calcium activated potassium channels, respectively.

• 

  Fig. 2 Expressions of BK, SK2 and SK3 proteins corrected for β-actin in each sample. Values are shown in arbitrary units (A.U.) as mean±SEM of the human prostate tissue with either benign prostatic hypertrophy (BPH) or prostate cancer (CaP). *p<0.01 vs. BPH (Mann-Whitney test). BK and SK denote the large- and small-conductance calcium activated potassium channels, respectively.

• 

  Fig. 3 Representative examples (upper panel) and densitometric analyses (lower panel) of the PCR products for connexin (Cx) 26, Cx43 and Cx45 corrected for β-actin in each sample. The values are expressed in arbitrary densitometric units (A.D.U.) as mean±SEM of the human prostate tissue with either benign prostatic hypertrophy (BPH) or prostate cancer (CaP). *p<0.05 and †p<0.01 compared to BPH (Mann-Whitney test).

• 

  Fig. 4 Expressions of connexin (Cx) 26 and Cx43 protein corrected for β-actin in each sample. Values are shown in arbitrary units (A.U.) as mean±SEM of human prostate tissue with either benign prostatic hypertrophy (BPH) or prostate cancer (CaP).

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