It
On six human hepatocellular carcinoma (HCC) cell affects vascular endothelial cells and stimulates angiogenelines (KIM-1, KYN-1, KYN-2, KYN-3, HAK-1A, and HAKsis, and it influences bFGF-responsive cells to change their 1B), we examined expressions and functions of the promorphology and growth pattern, and to increase their migrateins and messenger RNAs (mRNAs) of basic fibroblast tory activities. 11,16,[18][19][20] To date, bFGF has been identified in growth factor (bFGF) and its receptor, i.e., fibroblast epithelial cells, endothelial cells, fibroblasts, macrophages, growth factor receptor-1 (FGFR-1), as well as mRNA exand extracellular matrix, in various organs in vivo, [11][12][13][14] and pressions of FGFR-2 ร4. All six cell lines expressed the its presence has also been confirmed in tumor tissues. 11,12,[21][22][23] proteins and mRNAs of bFGF and FGFR-1, and at least Schlze-Osthoff et al. 12 reported that tumors revealed a very one of FGFR-2 ร4 mRNAs. Two of the six cell lines (KYNheterogeneous staining pattern, e.g., bFGF can be expressed 1 and KYN-3) presented significant release of bFGF in
(1) only in tumor cells, (2) only on vascular endothelial cells, culture supernatant, while the release in the remaining or (3) only on macrophages. Identification of bFGF in tumor four cell lines was quite small. Addition of anti-bFGF tissues and in some cancerous cell lines allowed researchers neutralizing antibody (1, 10, or 20 mg/mL) to culture meto presume that bFGF is involved in the development and dium resulted in marked suppression of cell proliferaprogression of tumors. It is possible that bFGF produced by tion in all cell lines except HAK-1A. On the other hand, tumor cells affects proliferation of the tumor cells themselves addition of exogenous bFGF (0.1, 1, or 5 ng/mL) to culture through an autocrine or intracrine mechanism; or, bFGF acts medium stimulated cell proliferation except in KIM-1 on endothelial cells through a paracrine mechanism and and KYN-2. When KIM-1 was transplanted to nude mice stimulates angiogenesis; or bFGF induces higher productions and anti-bFGF antibody was injected subcutaneously to of plasminogen activators, various proteases, and collagena space surrounding the developed tumor, tumor prolifase, and contributes to infiltration and metastasis of tumor eration was significantly suppressed in nude mice that cells. 11,16,19,22 As high-affinity cell surface receptors for the received anti-bFGF antibody than in control mice, but FGF family, five types (fibroblast growth factor receptor there were no histological differences between the
[FGFR]-1 ร5) have been identified so far, [24][25][26][27] and their exgroups, including blood space formation in the stroma.
pressions have been reported in various tumor tissues and In conclusion, hepatocellular carcinoma (HCC) cells cell lines, and in normal endothelial cells. 14,17,28-30 may possess a proliferation mechanism regulated by an Expression of bFGF in normal liver tissues has been a autocrine mechanism, a paracrine mechanism, or both, matter of controversy. Hughes and Hall 14 conducted an imwhich are mediated by bFGF/FGFR. (HEPATOLOGY munohistochemical study and observed bFGF expressions at 1996;24:198-205.) high levels in normal hepatocytes. However, other studies before them reported that normal hepatocytes did not express The fibroblast growth factor (FGF) family is a group of bFGF, or they only weakly expressed bFGF. 12,13 On the other structurally related multifunctional mitogenic polypeptides, hand, Motoo et al. 21 identified high bFGF expressions in the and its members possess heparin-binding property. At prescytoplasm of hepatocellular carcinoma (HCC) cells of 16 of ent, nine members, from FGF-1 to FGF-9, have been identi-56 patients (29%), and another study reported the cultured fied. [1][2][3][4][5][6][7][8][9] The FGF family has been widely distributed in normal HCC cell line, SK Hep-1, can produce bFGF in vitro. 31 Normal and/or tumor tissues, and they are known to take various hepatocytes do not express the bFGF receptor, FGFR-1, while important roles, e.g., in angiogenesis, tissue regeneration, a hepatoblastoma cell line (HepG2) has been reported to exwound healing, and embryonic development. [10][11][12][13][14][15][16][17] Among the press this receptor. 14,32 Consequently, expressions of bFGF/ FGF family, basic fibroblast growth factor (bFGF, or FGF-2) FGFR could be involved in the angiogenesis and proliferation acts as a potent mitogen and as a differentiation factor for of HCC cells, even though their precise mechanism has not various mesoderm-and neuroectoderm-derived cells. 11 bFGF been fully elucidated.
In the present study, we examined (1) protein and messenger RNA (mRNA) expressions of bFGF and FGFR1 ร4, and (2) proliferation effects of bFGF on HCC cells through an Abbreviations: FGF, fibroblast growth factor; bFGF, basic fibroblast growth factor; autocrine mechanism both in vitro and in nude mice.
FGFR, fibroblast growth factor receptor; HCC, hepatocellular carcinoma; mRNA, messenger RNA; ELISA, enzyme-linked immunosorbent assay; PCR, polymerase chain reaction.