Key findings
The objective of this study was to study flax as an anticancer drug and provide a comparison between different cultivars of flaxseed cultivated in Egypt on the basis of their lignan content as well as their in vitro cytotoxic effect on different human cancer cell lines. The purified hydrolysates from different cultivars of Flaxseed were tested against three different breast cancer cell lines, two ER + (MCF-7& T47D) and one triple negative (MDA-MB231), in addition to a colorectal (HCT-116) and cervix (HELA) cancer cell lines. PFH-G9 hydrolysate showed the most effective cytotoxic activity against HELA, MCF7 and T47D cell lines with IC50 17.4, 13.8 and 15.8 µg/ml, respectively. The high anticancer activity of PFH-G9 could be attributed to its content of SDG as the HPLC analysis had shown that PFH-G9 contains the highest concentration of SDG (81.64 mg/g) when compared to the other cultivars. Matrix metalloproteinases (MMPs) have a substantial role in the classic hallmarks of cancer including tumor growth and the multistep processes of invasion and metastasis. MMP-2 and MMP-9 were investigated as one of the possible anticancer mechanisms of flaxseed. The results showed that PFH-G9 significantly attenuated MMP-2 and MMP-9 levels in T47D cells although, TAM an estrogen receptor modulator used in ER positive breast cancer patients treatment significantly enhanced MMP-2 and MMP-9 levels in T47D cells. VEGF has a pivotal role in regulation of angiogenesis, a physiological process which is very essential to survival of cancer cells, together with cell proliferation and migration. Cancer usually enhances VEGF expression, increasing its concentration due to tumor aggression and the poor prognosis, hence VEGF is involved in cancer pathology. In the present study, significant decrease in VEGF expression was detected after treatments with PFH-G9 and TAM. Apoptosis (or Programmed Cell Death Type I) is as a safeguard system preventing metastasis at all crucial steps and preventing cancer progression. Apoptosis is a caspase-dependent process which has a direct effect on the development, differentiation and proliferation of cancer. Both PFH-G9 and TAM significantly decreased p53 levels in T47D that expresses mutant p53 in T47D of breast cancer cell line that led to massive apoptosis. In EAC-bearing mice. FS and FSM were found to repress the tumor growth. All flaxseed diets; FO, FS, and FSM significantly reduced the expression of Ki-67; a nuclear protein expressed in proliferated cells and is used as cell proliferation marker. The results show the antitumor activity of Egyptian flaxseed that involved apoptotic, antiangiogenic and antimetastatic effects.
ABSTRACT
The objective of our study is to highlight the therapeutic effect and mechanism of action by which purified Flaxseed hydrolysate (PFH) which is a lignan rich fraction exerts its anticancer activity on a human breast cancer cell line (T47D) and in mice bearing tumor. HPLC analysis of PFH of six flaxseed cultivars had shown that PFH of the cultivar Giza 9 (PFH-G9) contains the highest concentration of SDG (81.64 mg/g). The in vitro cytotoxic potentiality of PFH’s of six flaxseed cultivars was screened against a panel of human cancer cell lines. PFH -G9 showed the most significant cytotoxic activity against ER-receptor positive breast cell lines MCF7 and T47D with IC50 13.8 and 15.8 µg/ml, respectively. Moreover, PFH-G9 reduced the expression of the metastasis marker, 1-α, metalloproteinases and vascular endothelial growth factor (VEGF), one of the most potent stimulators of angiogenesis, while it increased the caspase-3 dependent apoptosis. Our study also showed that dietary intake of 10% of Giza 9 Flaxseeds (FS), fixed oil (FSO) or Flax meal (FSM) twice daily for 3 weeks in mice-bearing solid Ehrlich ascites carcinoma (EAC) resulted in reducing the tumor volume, the expression of estrogen, insulin growth factor, progesterone, VEGF and MMP-2, but enhanced expression of caspase-3.
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