TURNING OFF CANCER 63community argued for HBV No one in either community dared to sug-
gest that nutrition had anything to do with this disease.
We wanted to know about the effect of casein on HBV-induced liver
cancer in mice. This was a big step. It went beyond aflatoxin as a carcino-
gen and rats as a species. A brilliant young graduate student from China in
my group, Jifan Hu, initiated studies to answer this question and was later
joined by Dr. Zhiqiang Cheng. We needed a colony of these transgenic
mice. There were two such "breeds" of mice, one living in LaJolla, Califor-
nia, the other in Rockville, Maryland. Each strain had a different piece of
HBV gene stuck in the genes of their livers, and each was therefore highly
prone to liver cancer. I contacted the responsible researchers and inquired
about their helping us to establish our own mouse colony. Both research
groups asked what we wanted to do and both were inclined to think that
studying the protein effect was foolish. I also sought a research grant to
study this question and it was rejected. The reviewers did nol take kindly
to the idea of a nutritional effect on a virus-induced cancer, especially of
a dietary protein effect. I was beginning to wonder: was I now being too
explicit in questioning the mythical health value of protein? The reviews
of the grant proposal certainly indicated this possibility.
We eventually obtained funding, did the study on both strains of
mice and got essentially the same result as we did with the rats.^47 ,48 You can
see the results for yourself. The adjoining picture (Chart 3.10^47 ) shows
what a cross-section of the mouse livers looks like under a microscope.
The dark-colored material is indicative of cancer development (ignore
the "hole"; that's only a cross-section of a vein). There is intense early
cancer formation in the 22% casein animals (D), much less in the 14%
casein animals (C), and none in the 6% casein animals (B); the remain-
ing picture (A) shows a liver having no virus gene (the control).
The adjoining graph (Chart 3.1147) shows the expression (activity) of
two HBV genes that cause cancer inserted in the mouse liver. Both the
picture and the graph show the same thing: the 22% casein diet turned
on expression of the viral gene to cause cancer, whereas the 6% casein
diet showed almost no such activity.
By this time, we had more than enough information to conclude that
casein, that sacred protein of cow's milk, dramatically promotes liver
cancer in:
- rats dosed with aflatoxin
- mice infected with HBV