Macrophage infiltration correlates with tumor stage and angiogenesis in human malignant melanoma: possible involvement of TNFalpha and IL-1alpha

Significance and relationship between infiltrating inflammatory cell and tumor angiogenesis in hepatocellular carcinoma tissues

AIM: To investigate the relationship between infiltrating inflammatory cell and tumor angiogenesis in hepatocellular carcinoma (HCC) tissues and their clinicopathological features.

METHODS: The paraffin-embedded specimens from 70 cases with HCC were stained using EliVision immunohistochemistry with mAbs against CD68, tryptase, and CD34. The counts of tumor-associated macrophage (TAM), mast cell (MC) and tumor microvessel (MV) were performed in the tissue sections.

RESULTS: The mean counts of TAM, MC, and MV in HCC tissues were significantly higher than those in pericarcinomatous liver tissues (TAM: 69.31 ± 11.58 vs 40.23 ± 10.36; MC: 16.74 ± 5.67 vs 7.59 ± 4.18; MV: 70.11 ± 12.45 vs 38.52 ± 11.16, P<0.01). The MV count in the patients with metastasis was markedly higher than that with non-metastasis (P < 0.01). In addition, the MC count in the patients with poorly differentiated HCC was obviously higher than that with well differentiated HCC (P < 0.01). The correlation analysis showed that the TAM count was significantly correlated with the count of MV (r ＝ 0.712, P < 0.01), and the MC count was obviously correlated with the MV count (r ＝ 0.336, P < 0.05).

CONCLUSION: TAM and MC might be closely related to the enhancement of tumor angiogenesis. The MV count might be associated with tumor invasion and metastasis. Moreover, the MC count might be associated with tumor differentiation and prognosis of HCC.

Expression of thymidine phosphorylase by macrophages in colorectal cancer tissues

AIM: To detect the thymidine phosphorylase (dThdPase) expression in human colorectal cancer tissues and cells.

METHODS: Forty specimens resected from patients with colorectal cancer were immunohistochemically stained by 654-1, anti-dThdPase monoclonal antibody, PG-M1, anti-macrophage marker CD68 monoclonal antibody. Morphometrical analysis and positive cell counting were performed. In 27 of 40 specimens, dThdPase activity was also assayed by HPLC. Otherwise, the dThdPase level was measured by ELISA in 6 colorectal cancer cell lines, LS174T, Clone A, Colo320, CX-1, Lovo, and MIP101, as well as in 2 macrophage-like cell lines, THP-1 and U937.

RESULTS: dThdPase activity was significantly increased in cancer tissues compared with adjacent normal tissue (P < 0.01). In immunohistochemical analysis, it was confirmed that most cells expressed dThdPase were the stromal cells surrounding cancer nests or along the invasive margin of cancer. Based on their morphometrical characteristics, we found that most of them were tumor-associated macrophages (TAMs). The number of dThdPase-positive stromal cells was significantly correlated with the number of CD68-positive macrophages (r = 0.76, P < 0.0001). By ELISA, 18.2 unit/mg and 19.3 unit/mg of dThdPase protein were detected in THP-1 and U937, but only little was detected in 6 colorectal cancer cell lines.

CONCLUSION: The present data suggest that dThdPase expression is seldom detected in colorectal carcinoma cells. TAM is the most important source of dThdPase in colorectal cancer tissues.

Mechanism and its regulation of tumor-induced angiogenesis

Tumor angiogenesis is the proliferation of a network of blood vessels that penetrates into cancerous growths, supplying nutrients and oxygen and removing waste products. The process of angiogenesis plays an important role in many physiological and pathological conditions. Solid tumors depend on angiogenesis for growth and metastasis in a hostile environment. In the prevascular phase, the tumor is rarely larger than 2 to 3 mm³ and may contain a million or more cells. Up to this size, tumor cells can obtain the necessary oxygen and nutrient supplies required for growth and survival by simple passive diffusion. The properties of tumors to release and induce several angiogenic and anti-angiogenic factors which play crucial roles in regulating endothelial cell (EC) proliferation, migration, apoptosis or survival, cell-cell and cell-matrix adhesion through different intracellular signaling are thought to be the essential mechanisms during tumor-induced angiogenesis. Tumor angiogenesis actually starts with tumor cells releasing molecules that send signals to surrounding normal host tissue. This signaling activates certain genes in the host tissue that, in turn, make proteins to encourage growth of new blood vessels. In this review, we focus the mechanisms of tumor-induced angiogenesis, with an emphasis on the regulatory role of several angiogenic and anti-angiogenic agents during the angiogenic process in tumors. Advances in understanding the mechanisms of tumor angiogenesis have led to the development of several most effective anti-angiogenic and anti-metastatic therapeutic agents and also have provided several techniques for the regulation of cancer's angiogenic switch. The suggestion is made that standard cytotoxic chemotherapy and angiogenesis inhibitors used in combination may produce complementary therapeutic benefits in the treatment of cancer.