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Antitumor Compounds From Halophilic Streptomyces violaceorubidus M4 Against Triple-Negative Breast Cancer
Atousa Zia1, Ensieh Salehghamari2, Hanieh Jalali3
1Department of molecular medicine, Pavia University, Pavia, Italy.
Abstract:
Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer characterized by the absence of estrogen and progesterone receptors and minimal HER2 expression, restricting the available treatment options. Actinobacteria have emerged as promising sources of anticancer compounds because of their remarkable ability to produce beneficial compounds. This study aimed to evaluate the antitumor effects of the halophilic Streptomyces violaceorubidus M4 extract on TNBC both in vitro and in vivo. The extracted compounds were analyzed by LC-MS. MTT and annexin-PI assays were used to assess the apoptosis-inducing effects of the compounds on MDA-MB-231 and MCF-10A cells. The expression of apoptosis-related BAX, BCL2, P53, CASPASE-8, and CASPASE-9 genes was analyzed using Real-time PCR. A TNBC mouse model was established using 4T1 cell transplantation, and the animals received the extract intravenously for 21 days. S. violaceorubidus M4 contained bioactive compounds, including amino acids, carboxylic acids, coumarins, isoflavones, phosphatidylcholine, tetrahydroxyanthraquinone, and flavonoids. The extract demonstrated selective cytotoxicity against MDA-MB-231 cells, with an IC50 of 48.04 μg/mL after 48 h, while the IC50 for MCF-10A cells was 132 μg/mL. The reduction in Cas-9 expression alongside the elevation of Cas-8 and P53 expression suggests the participation of the extrinsic pathway in the process of apoptosis. Histopathological evaluation of tumor tissues from mouse models showed that the extract injection reduced the number of mitotic cells, nuclear pleomorphism, and angiogenesis in tumor tissue. This study suggests that S. violaceorubidus M4 has a pronounced anticancer effect on TNBC and can be considered for the production of anticancer substances.
Insights
This study found that a Streptomyces violaceorubidus M4 extract effectively targets triple-negative breast cancer (TNBC) cells, showing significant antitumor effects in vitro and in vivo. The extract selectively kills cancer cells while modulating apoptosis pathways and reducing tumor growth in mice.
Area of Science:
- Microbiology
- Pharmacology
- Oncology
Background:
- Triple-negative breast cancer (TNBC) presents limited therapeutic options due to its aggressive nature and distinct receptor profile.
- Actinobacteria, particularly Streptomyces species, are recognized for producing diverse bioactive compounds with potential anticancer properties.
Purpose of the Study:
- To investigate the in vitro and in vivo antitumor efficacy of a halophilic Streptomyces violaceorubidus M4 extract against TNBC.
- To elucidate the mechanisms underlying the extract's cytotoxic and apoptotic effects on TNBC cells.
Main Methods:
- Chemical profiling of S. violaceorubidus M4 extract using LC-MS.
- In vitro cytotoxicity and apoptosis assays (MTT, Annexin-PI) on MDA-MB-231 (TNBC) and MCF-10A cells.
- Gene expression analysis (Real-time PCR) of apoptosis-related markers (BAX, BCL2, P53, CASPASE-8, CASPASE-9).
- In vivo efficacy assessment in a TNBC mouse model (4T1 cell transplantation) with intravenous extract administration.
Main Results:
- The S. violaceorubidus M4 extract contains various bioactive compounds, including flavonoids and coumarins.
- Selective cytotoxicity against MDA-MB-231 cells (IC50 = 48.04 μg/mL) compared to normal cells (IC50 = 132 μg/mL).
- Apoptosis induction via the extrinsic pathway, indicated by altered CASP8, CASP9, and P53 expression.
- In vivo, the extract reduced mitotic cells, nuclear pleomorphism, and angiogenesis in TNBC tumor tissues.
Conclusions:
- Streptomyces violaceorubidus M4 extract exhibits significant selective anticancer activity against triple-negative breast cancer.
- The extract's mechanism involves the induction of apoptosis and suppression of tumor growth and associated angiogenesis.
- S. violaceorubidus M4 is a promising source for developing novel anticancer agents for TNBC treatment.
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