  A tumor often consists of multiple cell subpopulations (clones). Current
chemo-treatments often target one clone of a tumor. Although the drug kills
that clone, other clones overtake it and the tumor reoccurs. Genome sequencing
and computational analysis allows to computational dissection of clones from
tumors, while singe-cell genome sequencing including RNA-Seq allows to
profiling of these clones. This opens a new window for treating a tumor as a
system in which clones are evolving. Future cancer systems biology studies
should consider a tumor as an evolving system with multiple clones. Therefore,
topics discussed in Part 2 of this review include evolutionary dynamics of
clonal networks, early-warning signals for formation of fast-growing clones,
dissecting tumor heterogeneity, and modeling of clone-clone-stroma interactions
for drug resistance. The ultimate goal of the future systems biology analysis
is to obtain a whole-system understanding of a tumor and therefore provides a
more efficient and personalized management strategies for cancer patients.
