Immunohistochemical analysis using a commercial antibody to ARF6 showed a significant
increase in the observed sum of staining intensity (protein expression) and distribution
between cancer and matched normal samples (P = 0.047, Figure 1). In normal tissue 73% (N = 22) of the samples showed a higher proportion of weak
staining intensity relative to moderate staining (27%, NÂ =Â 8) but there were equal
numbers of cases showing both weak (NÂ =Â 15) and moderate staining intensity (NÂ =Â 15)
in tumour tissue (Figure 2). Thus, there was an observed higher level of moderate staining intensity in tumours
relative to normal tissue. Based on the hypothesis of increased staining/protein expression
in tumour samples, the difference was statistically significant (PÂ =Â 0.044). However,
there was no significant difference in staining distribution in tumour (score = 2,
N = 7; score = 3, N = 23) relative to normal tissue (score = 2, N = 8; score = 3,
NÂ =Â 22) (PÂ =Â 0.360). Thus, 77 and 73% of tumour and normal samples respectively showed
ARF6 staining in 60% of the tissue sample.
Figure 1. Immunohistochemical detection of ARF protein expression in a normal prostate tissue and b prostate cancer tissue scored as Gleason grade 9.
Figure 2. Comparison of the percentage of cancer and control patients showing, weak staining
(intensity score 1) and moderate staining (intensity score 2). Asterisk denotes significant difference (p  0.05) in moderate staining intensity between
normal and cancer patients.
Although the numbers of tumours are relatively small in this study, we made a preliminary
assessment of the patterns of Gleason scores (7, 8 and 9) relative to ARF6 intensity.
Gleason grade 6 was excluded from analysis due to small sample size (NÂ =Â 5). There
were a higher proportion of tumours with weak staining (67%, NÂ =Â 10) compared to moderate
staining (33%, NÂ =Â 5) when Gleason score was 7. For cases with Gleason scores ?8 the
pattern is reversed with a higher proportion of moderate staining (70%, NÂ =Â 7) relative
to weak staining (30%, NÂ =Â 3) suggesting a trend towards increased staining intensity
with increasing Gleason score.