Name: Flow Cytometry Analysis of Apoptosis and the Cell Cycle in Salidroside Treated MCF-7 Cells
Uploaded: 2023-06-09T12:20:00
Description: Watch this Scientific Journal Video about Flow Cytometry Analysis of Apoptosis and the Cell Cycle in Salidroside Treated MCF-7 Cells at JoVE.com

flow cytometry analysis of apoptosis and the cell cycle in salidroside treated mcf-7 cells

Salidroside&#039;s Mechanism in Suppressing MCF-7 Cell Migration and Proliferation

As one of the most commonly diagnosed cancers and most common malignancies, the latest statistics indicate that 2.3 million cases of breast cancer emerged around the world by 2020, accounting for 11.7% of all cancer cases1. Common symptoms of breast cancer include breast tenderness and tingling, breast lumps and pain, nipple discharge, erosion or sunken skin, and enlarged axillary lymph nodes1,2. Even more alarming, the number of new cases and the overall incidence of breast cancer continues to increase at an overwhelming rate each year, accounting for 6.9% of cancer-related deaths1. At present, breast cancer intervention still mainly involves chemotherapy, surgery, radiotherapy, and comprehensive treatment. Although treatment can effectively reduce the recurrence rate and mortality rate of patients, long-term treatment application often causes produce multidrug resistance, large-area hair loss, nausea and vomiting, and serious mental and psychological burden2,3. Notably, the potential risk of multiple organ metastases from breast cancer also forces people to seek novel herbal sources of drug therapy4,5.
Phosphoinositide 3 kinase (PI3K)-mediated signaling is implicated in the growth, proliferation, and survival of breast cancer through splicing that affects the expression of multiple genes6. As a downstream signal-sensing protein of PI3K, numerous evidence suggests that protein kinase B (AKT) could couple with the mammalian target of rapamycin (mTOR) protein to further increase breast cancer7,8,9. Moreover, the deactivation of PI3K/AKT/mTOR signaling has also been claimed to be a key component in drugs inhibiting malignant proliferation and stimulating apoptosis in breast cancer10,11,12. It is well known that extreme hypoxia in the tumor microenvironment forces a massive surge in hypoxia-inducible factor 1 alpha (HIF-1&#945;), which further worsens the progression of breast cancer13,14,15. In parallel, AKT stimulation also leads to excessive accumulation of HIF-1&#945;, limiting apoptosis in breast cancer samples16,17. Interestingly, the activation of PI3K-AKT-HIF-1&#945; signaling has been confirmed to be involved in pathologic progression and metastasis in a variety of cancers, including lung cancer18, colorectal cancer19, ovarian cancer20, and prostate cancer21. In addition to being orchestrated by HIF-1&#945;, forked head transcription factor 1 (FoxO1) overexpression is also triggered by AKT signaling stimulation, which promotes cycle arrest and the inhibition of apoptosis in breast cancer cells22,23. Together, the above solid evidence suggests that the inhibition of the cascade of PI3K-AKT-HIF-1&#945;-FoxO1 signaling may be a potential novel target for drug therapy in breast cancer.
Salidroside (Sal) has been widely demonstrated to exert anti-cancer24,25, anti-hypoxia26,27,28,29, and immune-enhancing pharmacological activities30. It is a light brown or brown powder that is easily soluble in water, is a type of phenylethanoid glycoside, and has a chemical structure formula of C14H20O7 and a molecular weight of 300.331,32. Modern pharmacological investigations have demonstrated that Sal can promote the apoptosis of gastric cancer cells by restraining PI3K-AKT-mTOR signaling24. Further evidence also suggests that the suppression of PI3K-AKT-HIF-1&#945; signaling by Sal treatment may contribute to the apoptosis of cancer cells by enhancing their sensitivity to chemotherapeutic agents25. Evidence also suggests that Sal restricts cell migration and invasion and causes cycle arrest by promoting apoptosis in the human breast cancer MCF-7 cells33,34. However, it remains to be seen whether Sal can regulate PI3K-AKT-HIF-1&#945;-FoxO1 signaling and inhibit the malignant proliferation of MCF-7 cells. Therefore, this protocol aimed to explore the effects of Sal on MCF-7 cell migration, invasion, cell cycle, and apoptosis via the PI3K-AKT-HIF-1&#945;-FoxO1 pathway. The integrated research strategies comprising conventional, low-cost, and independent experiments, such as cell migration and invasion assessments, apoptosis and cell cycle detection by flow cytometry, reactive oxygen species (ROS) and Ca2+ fluorescence determination, etc., can provide a reference for the overall design of experiments for anti-cancer research with traditional herbal medicine. The experimental process of this study is shown in Figure 1.

Author Spotlight: Exploring Salidroside&#039;s Molecular Mechanisms in Breast Cancer Treatment 

Exploring the Pharmacological Action and Molecular Mechanism of Salidroside in Inhibiting MCF-7 Cell Proliferation and Migration

We focus on exploring active compounds derived from natural products and their potential in treating breast cancer. So specifically we aim to elucidate the pharmacologic effects of salidroside and its molecular mechanisms in combining breast cancer. Currently, reliable experimental techniques are lacking to validate salidroside's molecular targets in treating breast cancer.One significant finding in the field is a potential molecular mechanism of salidroside in enhancing the proliferation and migration of MCF7 cells through the regulation of PI3K/AKT/HIF-1 alpha/FoxO1 signaling. The laboratory's future research directly is to explore the pathophysiological mechanisms underlying breast cancer onset, development, prognosis and outcome. Additionally, we screen for active small molecular drugs derived from natural sources that may add in breast cancer prevention and treatment.

Watch this Scientific Journal Video about Flow Cytometry Analysis of Apoptosis and the Cell Cycle in Salidroside Treated MCF-7 Cells at JoVE.com

Flow Cytometry Analysis of Apoptosis and the Cell Cycle in Salidroside Treated MCF-7 Cells  

To begin, harvest the trypsinized MCF7 cells. Next, stain the PBS suspended cells with an X in five of ITC, and propidium iodide, for 20 minutes. Then determine the number of apoptotic cells using a flow cytometer.For cell cycle analysis, mix the re-suspended cells with propidium iodide solution in a fresh tube, and incubate the mixture for 30 minutes. Then detect the sample using a flow cytometer. Salidroside increased the number of MCF7 cells in the early and late apoptotic stages.Meanwhile, compared with the control group, salidroside treatment also sharply increased the number of cells in the G0 G1 phase, while reducing the proportion of S phase cells.

flow-cytometry-analysis-apoptosis-cell-cycle-salidroside-treated-mcf

Research

JoVE Journal

Medicine

Salidroside (Sal) contains anti-carcinogenic, anti-hypoxic, and anti-inflammatory pharmacological activities. However, its underlying anti-breast cancer mechanisms have been only incompletely elucidated. Hence, this protocol intended to decode the potential of Sal in regulating the PI3K-AKT-HIF-1&#945;-FoxO1 pathway in the malignant proliferation of human breast cancer MCF-7 cells. First, the pharmacological activity of Sal against MCF-7 was evaluated by CCK-8 and cell scratch assays. Moreover, the resistance of MCF-7 cells was measured by migration and Matrigel invasion assays. For cell apoptosis and cycle assays, MCF-7 cells were processed in steps with annexin V-FITC/PI and cell cycle-staining detection kits for flow cytometry analyses, respectively. The levels of reactive oxygen species (ROS) and Ca2+ were examined by DCFH-DA and Fluo-4 AM immunofluorescence staining. The activities of Na+-K+-ATPase and Ca2+-ATPase were determined using the corresponding commercial kits. The protein and gene expression levels in apoptosis and the PI3K-AKT-HIF-1&#945;-FoxO1 pathway were further determined using western blot and qRT-PCR analyses, respectively. We found that Sal treatment significantly restricted the proliferation, migration, and invasion of MCF-7 cells with dose-dependent effects. Meanwhile, Sal administration also dramatically forced MCF-7 cells to undergo apoptosis and cell cycle arrest. The immunofluorescence tests showed that Sal observably stimulated ROS and Ca2+ production in MCF-7 cells. Further data confirmed that Sal promoted the expression levels of pro-apoptotic proteins, Bax, Bim, cleaved caspase-9/7/3, and their corresponding genes. Consistently, Sal intervention prominently reduced the expression of the Bcl-2, p-PI3K/PI3K, p-AKT/AKT, mTOR, HIF-1&#945;, and FoxO1 proteins and their corresponding genes. In conclusion, Sal can be used as a potential herb-derived compound for treating breast cancer, as it may reduce the malignant proliferation, migration, and invasion of MCF-7 cells by inhibiting the PI3K-AKT-HIF-1&#945;-FoxO1 pathway.

The present protocol describesa comprehensive strategy for evaluating the pharmacological action and mechanism of salidroside in inhibiting MCF-7 cell proliferation and migration.

Salidroside (Sal) contains anti-carcinogenic, anti-hypoxic, and anti-inflammatory pharmacological activities. However, its underlying anti-breast cancer ...

Evaluating the Migration and Invasion of Salidroside Treated MCF-7 Cells in a Wound Scratch Assay

To begin, incubate two milliliters of the cultured MCF-7 cells in a six-well plate until 90%confluency. In the grown cell monolayer, create a linear scratch wound down the center using a sterile pipette tip. Then capture the images with an optical microscope at different time intervals.For the transwell assay, suspend MCF-7 cells in a serum-free medium. Then see the cells in the upper transwell chamber, either pre-coded or non-coded with Matrigel. Add DMEM complete medium at the bottom of the transwell chamber to act as a chemical inducer.After 24 hours, remove the cells in the upper chamber and fix the remaining invasive and migrant cells using methanol. Stain the MCF-7 cells using crystal violet solution. Next, image the stained cells with an optical microscope.A dose dependent inhibitory effect of salidroside on cell proliferation was observed, with a 50%decline in cell vitality at 40 micromolar. Further, salidroside could inhibit the vitality of MCF-7 cells over time, with a 50%decrease in MCF-7 cell vitality after 24 hours of co-incubation. The wound-scratch assay showed an inhibitory effect for salidroside treatment on MCF-7 cells.Further, salidroside treatment significantly reduced the undesirable migration and invasion of MCF-7 cells.

Determining Na+-K+-ATPase and Ca2+-Mg2+-ATPase Activity in Salidroside Treated MCF-7 Cells

Using a bicinchoninic acid kit, measure the protein concentration of lysed MCF-7 cells following the manufacturer's instructions. Add the lysed cell samples into the corresponding groups in a 96-well plate. Then, add the working solution and incubate at 37 degrees Celsius for five minutes.Finally, measure the optical density values at 636 nanometers in a functional microplate reader. Salidroside restricted the enzyme vitalities of sodium potassium ATPases and calcium ATPase, indicating its potential role in promoting mitochondrial dysfunction.

DCFH-DA and Fluo-4 AM Fluorescence Staining of Salidroside Treated MCF-7 Cells

Add 10 micromolar of Dcfh-DA fluorescence probe to MCF7 cells and incubate at 37 degrees Celsius for 20 minutes. After incubation, remove the excess Dcfh-DA by washing the cells three times with PBS. Next, test the fluorescence intensity using a fluorescence microscope and an excitation wavelength of 488 nanometers, and an emission wavelength of 525 nanometers.Incubate the MC7 cells with a five micromolar Fluo-4 AM fluorescent probe solution for 45 minutes at 37 degrees Celsius. After washing the cells three times with PBS, determine the fluorescence intensity using a fluorescence microscope with excitation at 488 nanometers and emission at 516 nanometers. Salidroside significantly enhanced ROS fluorescence signals shown by Dcfh-DA immunofluorescent staining.Consistently, Salidroside intervention also distinctly elevated calcium production, evidenced by Fluo-4 AM immunofluorescent staining.

Analyzing Protein Expression in Salidroside Treated MCF-7 Cells by Western Blotting

Begin by adding two milliliters of MCF-7 cells containing different drugs into the wells of a six-well plate. Incubate the cell cultures for 24 hours at 37 degrees Celsius and 5%carbon dioxide. Harvest the cells by centrifugation at 560 x g for three minutes at four degrees Celsius.Then wash the cells twice with pre-cool PBS, centrifuging at 560 x g for three minutes between the washes. Add 50 microliters of lysis buffer to the washed cells and place the sample in an ice bath for 15 minutes. Then centrifuge the sample at 8, 550 x g for 10 minutes at four degrees Celsius, and collect the supernatant protein sample.Combine the protein sample with the loading buffer in a four to one ratio. Next, denature the mixture at 100 degrees Celsius for 10 minutes in a metal bath. Then cool the mixture at room temperature.Separate the protein sample using 10%SDS polyacrylamide gel electrophoresis. Transfer the proteins onto a 0.22 micrometer PVDF membrane. After blocking the membrane with 5%BSA, incubate it with the corresponding primary antibodies overnight at four degrees Celsius.The following day, incubate the membrane with goat anti-rabbit IgG secondary antibody at 37 degrees Celsius for two hours. Then develop the membranes using an ECL chemiluminescence solution and capture the images using a contactless quantitative Western blot imaging system. Western blot showed that salidroside treatment promoted the protein expression of the pro-apoptotic factors CC-9, CC-7, CC-3, Bim, and Bax while it inhibited the protein expression of anti-apoptotic BCL-2.Salidroside prominently limited the ratios of p-PI3K to PI3K and p-AKT to AKT. Meanwhile, the protein expression of mTOR, HIF-1 alpha, and Fox01 was also notably suppressed.

Determining Gene Expression in Salidroside Treated MCF-7 Cells Using qRT-PCR

Harvest the MCF-7 cells by centrifugalization at 560-G for three minutes, at four degrees Celsius. Add 500 microliters of buffered RL-1 to five times 10 to the six cells and mix thoroughly until no cell masses are visible. Next, transfer the cell homogenates to a DNA cleaning column embedded in the collection tube.Centrifuge the samples at 85-50-G for two minutes, at four degrees Celsius. After centrifuging, remove the DNA cleaning column, retaining the supernatant in the collection tube. Add 800 microliters of buffer RL-2 and 500 microliters of the supernatant, and mix gently.Next, transfer 700 microliters of the mixture into an RNA-only column embedded in the collection tube. Centrifuge the tube at 8, 550-G for one minute, at four degrees Celsius. Then discard the flow-through in the collection tube.Wash the RNA-only column first with 500 milliliters of buffer RW-1, and then with 700 milliliters of buffer RW-2, by centrifuging for one minute at 8, 550-G, and four degrees Celsius at each wash. After removing the residual RW-2 by centrifuging again, transfer the RNA only column to a new collection tube. Add 100 microliters of RNAs-free deionized water, preheated at 65 degrees Celsius to the center of the membrane in the RNA-only column, and wait for two minutes.Then centrifuge at 8, 550-G for one minute, at four degrees Celsius to collect the RNA solution. Set up the reaction mixture for PCR and then set the PCR reaction conditions of the system. Execute the QRT PCR procedure.QRT PCR showed that cylindricity treatment promoted the gene expression of the pro-apoptotic factors, CC-9, CC-7, CC-3, vim, and vax, while it inhibited the gene expression of anti-apoptotic BCL-2. Further, cylindricide administration reduced the gene expression levels of PI-3K, AKT, M-tor, HIF1-Alpha and Fox-01.