1 Directly kill tumor cells
As a monomer, Bee Venom Powder exists in a random coil structure in neutral aqueous solution, and as the pH value and ionic strength increase, melittin self-crosslinks to form a helical tetramer structure. Studies have found that the helical region of melittin and the angle between helices are different in different solutions. The surface of the helix in the helical structure is the first 21 polar amino acids, and the other side of the helix is non-polar amino acids. This amphipathic character is characteristic of membrane-bound peptides and transmembrane helices of membrane proteins.
This feature determines that melittin is easy to integrate into and destroy natural and synthetic phospholipid bilayers, thereby inhibiting cell growth and development, and has a strong cytotoxic effect on tumor cells. Because melittin destroys the cell membrane and leads to cell death, it does not need to enter the cell, and it can show its cytotoxicity to destroy tumor cells outside the cell. Guo Ju and other scholars found that melittin has a strong inhibitory effect on LNcap cells in the study of the inhibitory effect of Bee Venom Powder on LNcap cells, and the higher the concentration of melittin, the higher the inhibitory rate on cancer cells.
2 Induce tumor cell apoptosis
Apoptosis is a cell suicide program, including a series of morphological and biochemical changes, and the pathogenesis of most diseases is related to apoptosis. The ways to induce apoptosis mainly include endoplasmic reticulum pathway (such as the influence of Ca2 + channel), mitochondrial apoptosis pathway, death receptor pathway and other factors (such as radiosensitivity of tumor cells).
2.1 Effect of Ca2+ channels
When Ca2 + is released from the endoplasmic reticulum into the cytoplasm, it will activate calpain near the endoplasmic reticulum, and then act on caspases-12 (caspases-12) to activate and release it into the cytoplasm, thereby inducing cell apoptosis. Melittin can increase the permeability of cell membranes to ions, especially Na+ and Ca2+. Ca2+ can carry signals that activate cells to carry out their programmed functions.
The SARIS study found that calcium overload can induce apoptosis, and it is established by a variety of cells. CHU et al. found that Bee Venom Powder can induce Ca2+ influx through L-type Ca2+ channels in human osteoma cells MG63, increasing the intracellular Ca2+ concentration, leading to cell lysis and causing apoptosis of MG63 cells, and Ca2+ influx is not dependent on protein Kinase C and phospholipase A2 activity.
2.2 Mitochondrial apoptosis pathway
The active center of cell apoptosis regulation is the mitochondria. Under the stimulation of apoptosis factors, the mitochondria release pro-apoptotic factors such as cytochrome C, and the pro-apoptotic factors activate the caspases of intracellular caspases, and the activated caspases act in turn. In mitochondria, it promotes the release of cytochrome c. Bcl-2 family proteins can regulate the mitochondrial permeability transition pore, thereby regulating the release of cytochrome c from mitochondria to the cytoplasm, and play a key role in the regulation of apoptosis.
Research by Li Yumei et al. found that Bee Venom Powder can induce U2OS cell apoptosis, and can promote changes in the expression of anti-apoptotic proteins Bcl-2 and Bax proteins in U2OS cells, and changes in the ratio of Bax/Bcl-2, first activate caspases-9, and then activate caspases-3, finally induces apoptosis. After Zhang Chen treated BEL-7402 cells with different concentrations of melittin, the expression rate of mitochondrial membrane protein 7A6 increased, and the expression rate increased with the increase of melittin concentration, which can promote the apoptosis of liver cancer cells .
2.3 Death receptor pathway
The death receptor-mediated apoptosis pathway is mainly through transmembrane receptors to transmit signals from extracellular to intracellular, after the adapter protein binds to the receptor, the execution protein binds to the adapter protein again, thereby inducing cell apoptosis. Its pathway mainly includes activation-induced tumor necrosis factor receptor, tumor necrosis factor-related apoptosis-inducing ligand (TNF-related apoptosis-inducing ligand, TRAIL) and FAS/FASL. After Zhang Chen treated BEL-7402 cells with Bee Venom Powder, according to the results of RT-PCR amplification, it was found that melittin had an effect on Fas protein related to cell apoptosis. expression related.
Scholars such as Wang Chen found that melittin can promote the sensitivity of human liver cancer cells to TRAIL by constructing a mouse tumor-bearing model, and can enhance the activation of calcium/calmodulin-dependent protein kinase Ⅱ-transforming growth factor β-activated kinase 1-mitogen Proactivation of the protein kinase kinase-JNK/p38 signaling pathway and inhibition of nuclear factor-κB inhibiting the protein kinase-nuclear factor-κB signaling pathway synergistically with TRAIL to induce apoptosis in human hepatocellular carcinoma cells.
2.4 Improving the radiosensitivity of tumor cells
Radiation therapy and chemotherapy are important means of treating tumors. Generally speaking, the effect of tumor radiotherapy is related to radiosensitivity, that is, those with strong radiosensitivity have better therapeutic effect, and those with poor radiosensitivity have poor therapeutic effect. Foreign scholars have found that melittin can enhance the radiosensitivity of esophageal cancer, resulting in enhanced apoptosis in vitro and in vivo. Scholars believe that melittin and radiation-induced apoptosis may be activated through the Bax / Bcl-2 pathway, and thus conclude that melittin-mediated radiosensitization may be partly due to the regulation of Bcl-2 protein.
After Yang Xi received different doses of X-ray radiation on nasopharyngeal carcinoma CNE-2 cells, he found that the cell survival scores in the normoxia group and the hypoxia group were significantly lower than before when melittin was combined. The sensitization ratios of melittin in CNE-2 normoxic and hypoxic cells were 1.07 and 1.13, respectively, and melittin could increase the total apoptosis rate of normoxic and hypoxic CNE-2 cells after irradiation. Therefore, melittin can effectively increase the radiosensitivity of tumor cells and promote the induction of apoptosis of tumor cells.
3 Inhibit the invasion and metastasis of tumor cells
Blood vessels are one of the important channels for tumor cell invasion and metastasis, and tumor cells can flow to all parts of the body through blood vessels. Therefore, we can inhibit tumor cell invasion and metastasis by inhibiting tumor-associated angiogenesis. Foreign scholars have found that melittin can inhibit tumor growth and tumor-associated angiogenesis in vivo induced by vascular endothelial growth factor A in Lewis lung cancer, and this inhibition of vascular endothelial growth factor A-induced proliferation and capillary differentiation has no cytotoxicity, which is consistent with vascular endothelial growth Factor 2 and cyclooxygenase-2 are associated with mitogen-activated protein kinase signaling. The biological processes of invasion and metastasis require disruption of the extracellular matrix.
Therefore, extracellular matrix degrading enzymes such as matrix metalloproteinases have become important drug targets for the regulation of tumor invasion and metastasis. PARK studies have shown that melittin can inhibit phorbol ester-stimulated cancer cell invasion by inhibiting the expression of matrix metalloproteinase-9, and the inhibition of matrix metalloproteinase-9 expression is due to the inhibition of phosphorylation of extracellular regulated protein kinase ( extracellular regulated protein kinase (ERK) and phosphorylated Jun levels resulted in effects on AP-1 and nuclear factor κB.
Thus it was shown that melittin can inhibit the invasion and metastasis of cancer cells by preventing the degradation of extracellular matrix. LIU studies revealed that Rac1 is a key regulator of liver cancer cell metastasis in vivo and in vitro. The Jun pathway is one of the Rac1-dependent pathways, and Bee Venom Powder can largely inhibit the movement of cells by inhibiting the Jun pathway, thereby preventing the metastasis of liver cancer cells in vivo.
4 Immunomodulatory effects
T cell regulation is an important part of cellular immune regulation in the human body. There is an important balance in T cell regulation, that is, the balance of helper T cell (Th1)/Th2. The γ-interferon secreted by Th1 cells has anti- Tumor function, while interleukin-4 (interleukin, IL-4) secreted by Th2 cells can promote inflammation. If the Th1/Th2 balance is tilted towards Th1, the anti-tumor effect of T cells can be enhanced.
NAM et al. found that bee venom can selectively induce the development of Th1 cell lineage by up-regulating Tbet and increase the expression of Th1 cell-specific cytokine γ-interferon. Moreover, this effect is mediated by directly affecting CD4+ T cells, independent of any antigen-presenting cells.
Wang Qiubo found that the IL-2 content of the body increased significantly and the IL-4 content decreased after treating volunteers with bees, which led to the enhancement of Th1 cell function and played a positive role in regulating the body’s cellular immune function. Scholar Xiong Langping and other scholars found that Bee Venom Powder can up-regulate the Th1 ratio and γ-interferon concentration in the state of immune cell activation, and down-regulate the IL-4 concentration to affect immune cells, thereby improving the anti-tumor effect.
