The formation of fibrous capsule around the cancer nodule and of the septum
in the tumor is frequently observed with the development of hepatocellular
carcinoma MCC). We aimed to clarify how the capsule and septum were formed
during the growth of HCC. Liver samples surgically resected from 25 patien
ts with HCC were studied with in situ hybridization for type-I, -III, and -
IV procollagen. Type-I and -III procollagen-expressing cells, mostly (x-smo
oth muscle actin (SMA)positive, were increased in the fibrous capsule and i
n the septum between HCC nodules. These cells were also found at the invasi
on front of HCC and around the necrotic cancer tissues. Type-IV procollagen
gene expression was mainly observed in mesenchymal cells localized in both
HCCs and non-cancerous liver. Cancer cells or hepatocytes did not express
any of these procollagen genes. The present study reveals that the capsule
and septum are mainly formed by oc-SMA-positive mesenchymal cells at the in
terface between two different tissues (e.g., cancer nodule vs non-cancerous
liver or another cancer nodule). The wound healing occurs even in HCC. The
capsule formation may result from interaction between tumor and host liver
and interfere the growth and invasion of HCC.