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As shown in the following figure, cancer cells proliferate through cell division. Cell division occurs in a cycle with 4 major stages from G1 phase to S then G2 and finally reaching the mitosis M phase.

Numerous studies have shown that low-dose (1~10ug/ml) dammarane sapogenins and derivative compounds can arrest the cell cycle at the G1 phase at low concentrations. Therefore, cell proliferation was stopped.

In addition, at low concentrations, dammarane sapogenins can induce malignant cell differentiation to the benign form. When cancer is treated with low concentrations of dammarane sapogenins or its derivatives, malignant cells which are densely populated and bear round or polygonal shapes (figure a) are transformed into spindle shaped cells in a loose array (figure b), typical of the benign morphology. Since cancer develops from a single abnormal cell, long term, low dose use of dammarane sapogenins may halt any potential cancerous cell transformation, as well, stimulate differentiation of cancer cells, therefore prevent cancer development.


Apoptosis is a special form of cell death, also named programmed cell death. Dammarane sapogenins and derivatives may activate a series of enzymes inside cells in an orderly fashion and resulting in cancer death through activating apoptosis pathways.

The figure 1 shows, after 25ug/ml dammarane sapogenins treatment, a typical microphotograph of apoptotic cells, where clusters of small vesicles (apoptotic bodies) are seen in treated cancer cells.

Dammarane sapogenins and derivative compounds are effective against a very wide spectrum of cancer cell types. The pro-apoptotic effect of dammarane sapogenins has been demonstrated in various cancer cells:

Pancreatic cancer: BXPC-3, Capan-1, MIAPaCa
Breast cancer: MCF7, MCF7adr, MDA435LCC6M, MDA435LCC6W
Brain cancer: U87, U87delta, 9L, SF188, SF120, SF210, U126, U373
Prostate cancer: LNCaP, PC3
Intestinal cancer: HCT15
Gastric cancer: Keto
Melanoma: B16, MMRU, SK-mel-110
Lung cancer: H460, MS-1, H838
Liver cancer: H22
Sarcoma: S180

Dammarane sapogenins induce cancer cell apoptosis through multiple mechanisms:

  • Activate caspases 3 & 8 (figure 2)
  • Inhibit Akt phosphorylation to shut down proliferative process (figure 3)
  • Increase intracellular free radical levels (figure 4)

In summary, the pro-apoptotic mechanisms of dammarane sapogenins can be illustrated in following figures:

 


By far, it is well recognized that the overexpression of glycoprotein P-GP is one of the major mechanisms of multidrug resistance in cancer cells. The P-gp protein functions as an efflux pump to transport cytotoxic drugs out of cells so that cancer cells can survive the challenge of anti-cancer drugs.

Although several candidate chemicals for multidrug resistance reversal have been successfully experimented in in-vitro cell models, their mono-targeting property and associated severe adverse effects prevent their wide use in clinical medical practice.

Dr. Jia at UBC found that Dammarane Sapogenins can considerably inhibit the function of P-gp in tumor cells. In breast cancer cells, the treatment of Dammarane Sapogenins for 15 minutes significantly inhibited the function of P-gp as the fluorescence-tagged drug accumulated in Dammarane Sapogenin-treated cancer cells (figure b) in comparison with extremely weak fluorescence in untreated cancer cells (Figure a). This experiment proves that Dammarane Sapogenins are able to block the function of P-gp and raises the anti-cancer drug concentration in cancer cells so as to reverse the multidrug resistance and improve the chemotherapy efficacy.


Experiments in drug-resistant tumor cells have provided the proof that Dammarane Sapogenins can sensitize drug-resistant tumor cells to anti-cancer drugs; for example, the threshold concentration of taxol in drug-resistant tumor cells decreased from 100uM to 10uM in with and without Dammarane Sapogenins treatments, suggesting Dammarane Sapogenins synergize with taxol and sensitize drug-resistant tumor cells to chemotherapy by 10 fold (figure 1).

Figure 1. The effect of Dammarane Sapogenins on drug-resistant cancer cells

Gemzar is the first-line drug for the treatment of pancreatic cancer. As shown in figure 2, Dammarane Sapogenins increase the sensitivity of pancreatic cancer cells to gemzar, and 90% of tumor cells died in the combination treatment of gemzar and Dammarane Sapogenins, compared to 40% in gemzar treatment alone.

As same, the treatment with Dammarane Sapogenins drastically disproves drug-resistant p388 leukemic cells of drug resistance, and decreases the IC50 of daunorubicin by more than 300 fold. Therefore, Dammarane Sapogenins display a superior synergistic effect with daunorubicin.


In addition to the above pleiotropic effects of dammarane sapogenins, our recent study demonstrated their usefulness in preventing estrogen-dependent breast cancer in particular.

Estrogen is a female hormone with important physiological functions; however, prolonged and excessive estrogen stimulation promotes breast cancer carcinogenesis. Furthermore, conclusive epidemiological evidence suggests that hormone replacement therapy for healthy postmenopausal women in western countries is associated with a small but substantial increase in breast cancer risk.

Our data showed that dammarane sapogenins compete with estrogen for estrogen receptors. Therefore, they prevent estrogen from binding to the receptors for their tumor stimulating effects. In a human breast cancer animal model, dammarane sapogenins or a dammarane sapogenin containing product completely blocked growth of the tumor even in the presence of high levels of estrogen. In addition, when dammarane sapogenins were used in combination with tamoxifen, a significant enhancement of the effect of the latter on killing breast cancer cells occurred.


To demonstrate the therapeutic efficacy of dammarane sapogenines, one must test it on animal tumor models before use on patients.

An example is shown in figure 1 which shows result of an experiment that used animals bearing malignant brain tumors. In this study, malignant glioma cells were implanted in the brain. Control animals only received saline while the experimental groups received dammarane sapogenins containing agent orally for 10 days. From the keplain-Meior surviving curves where the x-axis represents survival days and the y-axis is the percentage of animals that survived on each day, animals in the control group all died within 24 days while 40% animals treated with dammarane sapogenins containing agent in the dose group 25mg/kg survived. In addition, even at a low dosage, the animals lived longer compared to the control group, demonstrated by a right shift of the survival curve.

As shown in figure 2, tumor sizes of dammarane sapogenins treated animals were much smaller than in the control group suggesting an inhibition of tumor growth.

A similar tumor inhibitory effect was also seen in other tumor models including prostate cancer and pancreatic cancer (refer to table)