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Maitland Prostate cancer: from bench to bedside

is nevertheless useful and in the long term critical to Compensation and redundancy in cell
determine treatment targets, in an easily controlled signaling
biological system. At the next level of complexity, The transmission of external stimuli to the nuclei
the ability to co-culture multiple different populations of cancer cells has always been considered as a
from primary tissues offers something closer to the “pathway” by molecular biologists. A better description
original patient, but is confounded by resolution of however is as a network or system. The naïve linear
the individual cell types both during treatment and view of such signaling, for example when a growth
after treatment. Here the critical step has to be the factor binds to (one of) its receptors on the cell surface,
inclusion of (1) a vehicle or non-treated control and has now been dispelled by current targeted inhibition
(2) if possible a control of normal tissue from the studies. In a cell line, whose growth has become
same region of the prostate from the same patient. dependent on supplied growth factors, over perhaps
The latter remains a very rare occurrence in published a 20-year period of stress and adaptation in culture,
accounts of experimental prostate cancer treatments, such signaling networks have been degraded: what
which often consist of a cancer cell line (or two) and a cell does not require is frequently down-regulated,
one of the rare normal or non-malignant prostate and even mutated - a situation which is more
cell lines (such as PNT2 ) but more often involves prevalent in advanced cancer cells and tissues with
[25]
a primary culture of “normal” prostate which can be DNA replication and repair defects. Examples of the
purchased commercially . Any scientist setting out different drug sensitivities of multiple tissue derived
[26]
on a similar experimental programme must remember cells, and the weak “model” provided by the industry
that the culture media on which such primary cultures standard LNCaP cells for this are shown in Figure 1.
are maintained is often serum free and of a different The same was true during the development of the now
calcium content to that required to culture the common standard enzalutamide, as discussed earlier .
[16]
prostate cells such as PC3, DU145 and LNCaP. How
convincing would such a comparison be in another The relevance of pathway intermediates can be
biological system when the effects of foetal calf approached by gene knockout (by CRISPR for
serum in growth medium are also so manifold? The example) or gene expression knockdown (Si and
entire point of a defined culture medium has been to ShRNA). Such techniques are readily applied to
reduce the reliance on the “black box” effect of serum fast growing, clonogenic and easily transfected
constituents - which often vary between suppliers, and established cell lines, but their application in primary
indeed in batches from the same supplier. cultures of more clinical significance is substantially
harder. In addition, the “clean” statistics from a couple
The next level of complexity for treatment studies is of cell lines is not applicable in primary tissue-derived
the culture of tissue slices on artificial extra cellular material. Primary cultures are often heterogenous
matrix, or indeed on collagen sponges . These have (containing normal and malignant cells, as well as cells
[27]
the added advantage of retaining haematological cell at different stages of differentiation), but there is also
infiltrates, and include prostate stroma. However such substantial inter-patient variability in the response to
studies can only be considered as “window” treatment genetic manipulation. Therefore, sufficient numbers of
studies over a short period of time. In our own studies patient samples are required to achieve a “consensus”
of this system, the type of cell which proliferated view - if such an endpoint is actually achievable.
within the tissue slice was critically dependent on
the choice of growth medium. For example, in RPMI The ideal clinical trial from a scientist’s
medium, growth of the stromal component was viewpoint
apparent whereas in higher calcium medium, the The last statement brings me appropriately to the
epithelial component would react. Supplementation title and aim of the article. If we assume that the
of the culture medium with cholera toxin removed the ultimate aim of translational research in cancers is to
stromal proliferation but ultimately resulted in tissue understand what happens in the patient, the MDT for
degeneration. A short period of time (3-7 days) is fine, cancer treatment now has to extend beyond the clinic
but longer exposure/culture is likely to bias the final to the scientific researchers. Back in 2010, I asked
output. Tissue slicing strategies often also suffer from a genome sequencer, who was tracking oncogenic
the stress imposed upon the tissues at the periphery mutations in prostate cancer, what type of cancer
of the sample. Thus only cells within the centre of the their group needed for their studies. Expecting an
slice are credible candidates for treatment analyses answer of “high gleason grade”, or “castration-
as those on the outside are often too damaged and resistant”, or perhaps “a homogeneous mass”,
respond totally differently (as in a wound response) to the reply was actually “a BIG one”. Apparently the
be considered typical of the intact tissues. quality of material was less important, as the cellular
266 Journal of Cancer Metastasis and Treatment ¦ Volume 3 ¦ November 17, 2017