Transforming growth factor-β) is a peptide which has diverse biologic actions in human tissue and is thought to contribute to tumor development and progression. TGF-β inhibits the growth in variable types of epithelial cells and has a
protective
action in earlier phase of cancer development. But the tumor tissues can escape from the inhibitory effects of TGF-βafter a certain phase of growth, and then continue to proliferate. Production and secretion of TGF-β by tumor cells increases
according
to the progression of tumor and PAI-1 expression is known to be stimulated by TGF-βin tumor tissues.
The author intended to study the correlation of TGF-β1 with tumor invasion. Colon tissues were resected from 50 cancer patients. RNA was extracted from the tumor tissues and the peritumoral normal colon tissues. Messenger RNA(mRNA) of TGF-β1
was
measured by reverse transcription-polymerase chain reaction(RT-PCR). The TGF-β1 and the plasminogen activator inhibitor type-1(PAI-1) in tumor tissues were quantitated by enzyme-linked immunosorbent assay(ELISA).
The colon tissue did not differ in the TGF-β1 mRNA ratio between the tumor tissue and the peritumoral normal tissue at TNM stage I, but the amounts of TGF-β1 mRNA in tumor tissues were significantly higher than those in the normal tissues at
more
advanced TNM stages. As a result the differences in the TGF-β1 mRNA ratios between the tumor tissues and the normal tissues were statistically significant(p=0.0001).
The differences between TNM stage I and more advanced stages in TGF-β1 protein amount as estimated by immunohistochemical staining were very similar to those of TGF-β1 as measured by ELISA in which the p-value was 0.0508. But the difference in
TGF-β1
protein amount between the tumor tissues and the peritumoral normal tissues was statistically significant(p=0.0001). The difference between TNM stages in PAI-1 protein amount as measured by ELISA was not statistically significant(p=0.286), but
the
difference in PAI-1 protein amount between the tumor tissues and the peritumoral normal tissues was statistically significant(p=0.0021). On the basis of these results, the correlation coefficient between TGF-β1 and PI-1 in tumor tissues was
calculated
to be 0.647(p=0.0001).
On immunohisochemical staining of tumor sections, TGF-β1 was more intensely stained at the margin of the tumor infiltration site and the intensity of the staining was related with TGF-β1 protein amounts in each stage as measured by ELISA.
In conclusion, TGF-β1 expression increased in colon tissues at more advanced TNM stages than stage I, but more advanced stages were similar in TGF-β1 expression, indicating that TGF-β1 expression is related with tumor invasion. Therefore, it
appears
that TGF-β1 may have a role in tumor development and invasion at more advanced TNM stages of colon cancer.
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