Four prevalent anti-carcinoma principles of phytochemical extracts and medicines

The major comprehensive therapies against neoplasm, one of life-threatening diseases, include surgery, chemotherapy, radiotherapy, biotherapy etc. However, the curative effects are not satisfactory. In current anti-neoplasm medicines, herbal medicines perform important function, based on its holistic treatments and combination of tonification and purgation. It is characterized by low side-effect, alleviation for suffering, increase of life quality and sustainable efficacy. At present, the anti-neoplastic mechanism of herbal extracts covers the following areas.

1. Inhibition the tumor cells proliferation
What an important feature of tumor cells is the deregulation of cell division and proliferation. Herbal medicine extracts inhibit tumor cells division and proliferation mainly by regulating the expression of tumor-cell-cycle-related proteins or inhibiting the activity of tumor cells telomerase, thereby to play the function of inhibiting neoplasm growth. The research for the effect of sophocarpidine on hepatocellular carcinoma HepG2 cells proliferation by Si et al. indicates Cyclin D1 reducing, a cell G1 phase up regulating cytokines, and p16, p21 and p27 enhancing, cell G1 phase down regulating cytokines, after treated by sophocarpidine, which suggests that the anti-proliferation of sophocarpidine is associated with up or down expression of cell cycle regulating cytokines. He et al. found the inhibition effect of sophocarpidine on hepatocellular carcinoma HepG2 cells proliferation by MTT and cell cycle analysis, and during further detection for the effect of sophocarpidine on telomerase in hepatocellular carcinoma HepG2 cells line, they found sophocarpidine may inhibit the activity of telomerase in hepatocellular carcinoma HepG2 cells lines, suggesting that telomerase inhibition provide one alternative mechanism for sophocarpidine effect on inhibiting tumor cells proliferation.

2. The induction of apoptosis
Apoptosis, also known as programmed cell death (PCD), is a self-destructive process determined by genes and responsible for an active important protection of organisms. Generally, Tumor cells avoid death by utilizing this mechanism. Therefore, induction of apoptosis is an important method for target-therapy on neoplasm. Some researches show that induction apoptosis is the mechanism for lots of herbal extracts and medicines to realize neoplastic treatment. Resveratrol was observed to induce apoptosis in p53 positive HepG2 cells line, but perform no effect in p53 negative HepG2 cells line by Kuo et al., after treating these two cells lines by resveratrol, suggesting resveratrol may inhibit the tumor cells proliferation associated with tumor apoptosis through p38 pathway.

3. The induction of tumor cells differentiation
The atypia of malignant cell shows that tumor cells are on various differentiation stage and their occurrence and progression are driven by a small amount of tumor stem cells. Tumor stem cells lack of the respond to normal regulatory mechanism of differentiation. A new exploratory tumor treatment is involved in inducing tumor stem cells differentiation to terminal cells or to normal cells for depriving the self-renewal and malignant proliferation ability of tumor stem cells. In 1971, Friend et al. found the effects on inducing-differentiation of dimethyl sulfoxide (DMSO) in murine erythroleukemia cells lines and the synthesis of hemoglobin. Academician Wang et al. induce the differentiation of acute promyelocytic leukemia by retinoic acid and arsenic trioxide (As2O3). It is found by Du et al. that As2O3 reduce the malignant proliferation of poorly differentiated squamous cell carcinoma with the histological and immunohistochemical results suggesting that cancer cells is differentiating to mature and normal cells.

4. The reversal of tumor cells
Multi-drug resistance (MDR) is the primary reason for the failure of chemotherapy, referring to the fact when tumor cells shows resistance to one anti- neoplastic drug, they also cross resist to other drugs with different structures or mechanisms. The mechanism of MDR is associated with MDR-related proteins (MRP), lung resistance-related protein (LRP), P-glycoprotein (P-gp), glutathione (GSH), glutathione 2S transferase. Liu et al. found the injection of Panax Notoginseng Saponins (PNS) can inhibit the drug-pumping of tumor cells to partly achieve reversal of MDR of drug-resistant breast cancer cell by suppressing MDR genes and its P-gP glycoprotein product. Therefore, searching for MDR reversal agents and recovering the sensitivity of MDR cells to anti-neoplastic medicines provide a main neoplastic therapy.