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Reprinted from Sciexce, November 1, 146, Vol. 104, No, 2705, page 428,

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! Concept of Cancer
logy of cancer has been categorized under
‘; 4 transmissible virus on the one hand and
-'sin ou the other (not to mention a host of
‘.ests), there has Leen relatively little speca-
os biochemical mechanisms whereby any of
- vould Jeud to the process recognized as neg-
th Reeent studies by Beudle, Tainm, aud
the genetie control of biosynthetic renetions
Jas, Neurospora, have Pprevided a foundation
«pts of the biological regulation of growth,

   

“hy Wash, 1946, 32, 163-173), ou the ‘adap-
7a Neurospora mutant deficient in the syn-
“ie, has provided an experimental basis for
‘nalagy with neoplasia.
‘of Neurospora will row on medium con-
- “igur, salts, and biotin, which is to say that
“ds eupable of manufacturing all other essen-
4 As the result of uutations of single
“opacity for synthesis of varluus compounds
A similar process presumably accounts for
“val requirements of higher forms.
: violent treatment, a mutant strain of
37, has been isolated. which is incapable
‘ leucine, Ags a consequence, this strain
‘sand its growth is quantitatively regu-
abte gapply.
-¥. cultures Of loucineless Neurospora grown
woonnts of this amine acid will “fadapt??;

  

 
 
  

 

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that is, an exceptional .fragmeut of the mycelium will
gtow autonomously, irrespective of the available leucine,
and may under certain conditions Overgrow the culture
uutil the sugar is exhausted. By genctie analysis of
crosses between adapted and wild strains, it has been
shown that adaptation depends on the mutation, or re-
version, of the leucincless gene ta, an allele capable of
mediating the synthesis of leucine,

A culture of leucineless Neurospora has, then, two
growth potentialities: a regulated growth corresponding
to the leucine externally available to it, and, exccp-
tionally, autunomous growth on the basis of a gene muta-
tion leading to the synthesis of that metabolite,

Tf one correlates normal tissue eclls with a culture of

leucineless Neurospora, both regulated by their environ. |

ment, a simple analogy for cancer is evident-—the newly
found capacity of a cell to synthesize an essential metabo-
lite otherwise available only in limiting and regulatory
ainounts,

While the Neurospora experiments suggest a tiuta-
tional origin for this capacity, virus infection, by pro-
viding a missing Link for a block td enzyme system, eould
play a corresponding role. A consequence of this simple
concept is that cancer cells may be fourd to differ in
their growth factor requirements from cells of normal
origin when they are grown in vitro, _.

Josiua LEDERRERG

Oxborn Rutanical Laboratory, Yale University, and

College of Physicians and Surgeons, Columbia University

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