Background
:
Melanoma is one of the most common types of skin malignancies. Since
current therapies are suboptimal, considerable interest has focused on novel natural
-
based treatments. Toll
-
like receptors (TLRs) play an important role in evoking innate
immunity agains
t cancer cells. Zymosan, a known TLR
-
2 agonist, is a glucan derived from
yeast cell walls with promising immunomodulatory effects. The aim of this study was to
evaluate whether
Saccharomyces cerevisiae
-
derived z
ymosan
-
modulated skin
melanoma progression by
regulation of
TLR
-
2 expression in peritoneal macrophages and
serum TNF
-

level.
Methods:
Male C57BL/6 mice were divided into four groups: i) zymosan
-
treated (Z), ii)
Melanoma
-
bearing mice (M), iii) Melanoma
-
bearing mice treated with zymosan (ZM) and
iv) a
healthy control group (negative control). 15 days after melanoma induction, mice
were injected i.p. with zymosan (10

g) daily for 4 consecutive days. Mice were CO
2
-
euthanized and serum TNF
-
α level,
TLR
-
2
expression in peritoneal macrophages and
tumor gro
wth measured. Splenocytes were treated ex
-
vivo with zymosan to determine
viability and proliferation.
Results:
Tumor weight significantly decreased following therapeutic dosing with
zymosan (
P
<0.05). This was associated with zymosan
-
induced upregulation of
TLR
-
2
and TNF
-

mRNA in peritoneal mac
rophages and enhanced serum TNF
-

levels
(
P
<0.05).
Splenocyte number and viability were increased in a concentration
-
dependent
manner by zymosan.
Conclusion
s
:
Our study suggests that zymosan
-
induced upregulation of TL
R
-
2 and
TNF
-

gene expression and
of
TNF
-

release
;
together with
increased level
s
of
lymphocyte proliferation may play a role in
the
inhibition of melanoma progression.