Induction of apoptosis and non-apoptosis in human breast cancer cell line (MCF-7) by cisplatin and caffeine

Coffee consumption and breast cancer risk: a narrative review in the general population and in different subtypes of breast cancer

PURPOSE

Most of the existing literature reports no association or a slight negative association between coffee consumption and the risk of developing breast cancer. However, the level of risk differs when considering various subgroups, such as menopausal status, hormonal status of the tumor or genetic mutations. The present review based on a literature search sets the point on the potential influence of a common daily drink, coffee, on the risk of developing breast cancer in the general population, in different subgroups of women and the consequences of drinking coffee after breast cancer has been diagnosed and treated.

RESULTS

This review confirms that in the general population, there is no association between coffee intake and breast cancer risk or a slight protective effect, even at high dosages. Coffee is inversely associated with breast cancer risk in postmenopausal women and in women carrying a BRCA1 mutation. Possible risk differences exist between slow and fast caffeine metabolizers and with weight. Coffee consumption after breast cancer diagnosis and surgery, associated with tamoxifen and/or radiotherapy, reduced the occurrence of early events. The effects of coffee intake are less clear in other subgroups, mainly premenopausal women, women carrying a BRCA2 mutation and tumors with variable hormonal status (positive or negative for ER/PR) and would need additional studies.

Water-soluble propolis and bee pollen of Trigona spp. from South Sulawesi Indonesia induce apoptosis in the human breast cancer MCF-7 cell line

Bee products are best known as one of the beneficial natural products providing multiple pharmacological effects, such as antimicrobial, antiviral, anti-inflammatory and anticancer effects. The present study aimed to identify potent products derived from the stingless bee Trigona spp. from Luwu Utara (South Sulawesi, Indonesia), focussing on the water-soluble extract of propolis and bee pollen, against the proliferation of the human breast cancer MCF-7 cell line. The results from DPPH (2,2-diphenyl-1-picrylhydrazyl) method of antioxidant assay revealed that water-soluble propolis and bee pollen had high antioxidant activity, with half-maximal effective concentrations against DPPH radicals of 1.3 and 0.4 mg/ml, respectively. Additionally, water-soluble propolis and bee pollen exhibited a significant antiproliferative activity in MCF-7 cells, with IC₅₀ values of 10.8±0.06 and 18.6±0.03 mg/ml, respectively (P<0.05). Significant cytotoxic effects were observed after 24 h of treatment via microscopic and flow cytometric analysis, where a morphological change toward late apoptosis was observed. By contrast, honey had low antioxidant activity and no antiproliferative effect in MCF-7 cells. The water-soluble propolis also exerted its antiproliferative effect in the human keratinocyte HaCaT cell line. The antiproliferative activity was similar (P>0.05) at 24 and 48 h of treatment, with IC₅₀ at 2.7±0.06 mg/ml and <0.4 mg/ml, respectively. Notably, bee pollen was less toxic to HaCaT cells after 24 h of treatment than the water-soluble propolis, with IC₅₀>50 mg/ml. Its antiproliferative activity was significantly increased after 48 h of treatment, with IC₅₀ at 9.6±0.07 mg/ml (P<0.05). In addition, similar to other poplar propolis, the high-performance liquid chromatography-ultraviolet and electrospray ionisation mass spectrometry analyses revealed that caffeic acid phenethyl ester was not the main bioactive compound of the samples examined. Furthermore, two major proteins (between ~50 and 75 kDa) were identified in the water-soluble propolis and bee pollen. The present results suggested that water-soluble propolis and bee pollen may have the potential to be elaborated further as a breast anticancer therapy.

Oxidative Stress in Caffeine Action on the Proliferation and Death of Human Breast Cancer Cells MCF-7 and MDA-MB-231

To investigate the effects of caffeine on the proliferation and death of human breast cancer cells MCF-7 and MDA-MB-231. Cells were exposed to 1, 2.5, 5 and 10 mM of caffeine during 24 h, and oxidative stress (OS), cell proliferation and death, metabolic activity and DNA lesions were evaluated in the collected samples. Caffeine was cytotoxic to the cell lines analyzed, reducing cell proliferation and viability by interfering with the cellular metabolism and with lysosomal function. Although the cells presented different behaviors to treatment, in both cell lines, the drug induced OS and predominantly apoptosis. MCF-7 cells responded to OS induction (lipid peroxidation) increasing their antioxidant defenses. However, the OS generated induced oxidative DNA lesions, a finding not observed in MDA-MB-231 cells. The association of different scavengers with caffeine did not result in the recovery of cell viability, which suggests that it is not possible to attribute the caffeine induction of OS to only one of the specific ROS analyzed (superoxide anion, singlet oxygen and peroxyl radical). These results are promising and suggest that caffeine may be a good target for studies to prove its usefulness as an adjuvant in breast cancer treatment.

Bag-1 silencing enhanced chemotherapeutic drug-induced apoptosis in MCF-7 breast cancer cells affecting PI3K/Akt/mTOR and MAPK signaling pathways

The multifunctional anti-apoptotic Bag-1 protein has important roles in apoptosis, proteasome-mediated degradation, transcriptional regulation, and intracellular signaling. Bag-1 promotes cell survival and proliferation, and is overexpressed in breast cancer. Therefore, Bag-1-targeted therapy might be a promising strategy to treat breast cancer. However, the effects of Bag-1 silencing in combination with conventional chemotherapeutic drugs on cell viability and major signaling pathways have not yet been fully investigated in breast cancer cells. In this study, we investigated the cytotoxic effects of Bag-1 silencing, alone and in combination with cisplatin or paclitaxel treatment, in MCF-7 breast cancer cells. Bag-1 knockdown by shRNA or siRNA transfection sensitized MCF-7 cells to apoptosis induced by cisplatin or paclitaxel. Combination of Bag-1 silencing and drug treatment more potently downregulated the pro-survival PI3K/Akt/mTOR and p44/42 mitogen activated protein kinase (MAPK) pathways, and more potently upregulated the stress-activated p38 and SAPK/JNK MAPK pathways. Bag-1-silenced drug-treated cells had also highly reduced proliferative capacity, downregulated cyclin-cyclin dependent kinase complexes and upregulated tumor suppressors p21 and Rb. These results overall indicated that Bag-1 silencing enhanced cisplatin- or paclitaxel-induced cytotoxicity through multiple pathways. In conclusion, Bag-1 targeted therapy might enhance the therapeutic potential of conventional anti-cancer drugs in the treatment of breast cancer.

Platinum-Based Drugs Differentially Affect the Ultrastructure of Breast Cancer Cell Types

Breast cancer (BC) is the most common cause of cancer-related death worldwide. Although platinum-based drugs (PBDs) are effective anticancer agents, responsive patients eventually become resistant. While resistance of some cancers to PBDs has been explored, the cellular responses of BC cells are not studied yet. Therefore, we aim to assess the differential effects of PBDs on BC ultrastructure. Three representative cells were treated with different concentrations and timing of Cisplatin, Carboplatin, and Oxaliplatin. Changes on cell surface and ultrastructure were detected by scanning (SEM) and transmission electron microscope (TEM). In SEM, control cells were semiflattened containing microvilli with extending lamellipodia while treated ones were round with irregular surface and several pores, indicating drug entry. Prolonged treatment resembled distinct apoptotic features such as shrinkage, membrane blebs, and narrowing of lamellipodia with blunt microvilli. TEM detected PBDs' deposits that scattered among cellular organelles inducing structural distortion, lumen swelling, chromatin condensation, and nuclear fragmentation. Deposits were attracted to fat droplets, explained by drug hydrophobic properties, while later they were located close to cell membrane, suggesting drug efflux. Phagosomes with destructed organelles and deposits were detected as defending mechanism. Understanding BC cells response to PBDs might provide new insight for an effective treatment.

Lidocaine sensitizes the cytotoxicity of cisplatin in breast cancer cells via up-regulation of RARβ2 and RASSF1A demethylation

It has been reported that lidocaine is toxic to various types of cells. And a recent study has confirmed that lidocaine exerts a demethylation effect and regulates the proliferation of human breast cancer cell lines. To recognize a potential anti-tumor effect of lidocaine, we evaluated the DNA demethylation by lidocaine in human breast cancer lines, MCF-7 and MDA-MB-231 cells, and determined the influence of demethylation on the toxicity to these cells of cisplatin, which is a commonly utilized anti-tumor agent for breast cancer. Results demonstrated that lidocaine promoted a significant global genomic demethylation, and particularly in the promoters of tumor suppressive genes (TSGs), RARβ2 and RASSF1A. Further, the lidocaine treatment increased cisplatin-induced apoptosis and enhanced cisplatin-induced cytotoxicity. The combined treatment with both lidocaine and cisplatin promoted a significantly higher level of MCF-7 cell apoptosis than singular lidocaine or cisplatin treatment. Moreover, the abrogation of RARβ2 or RASSF1A expression inhibited such apoptosis. In conclusion, the present study confirms the demethylation effect of lidocaine in breast cancer cells, and found that the demethylation of RARβ2 and RASSF1A sensitized the cytotoxicity of cisplatin in breast cancer cells.