Exploring natural products as apoptosis modulators in cancers: insights into natural product-based therapeutic strategies

Cancer remains a leading cause of mortality globally, necessitating ongoing research and development of innovative therapeutic strategies. Natural products from plants, herbs, and marine species have shown great promise as anti-cancer therapies due to their bioactive components that alter cellular pathways, particularly apoptosis. This review explores the mechanism by which natural chemicals trigger the apoptosis of cancerous cells, which is crucial for eliminating them and halting tumor growth. These can affect the mitochondrial process by controlling the Bcl-2 protein family, increasing cytochrome c release, and activating caspases. They also activate death receptors like Fas and TRAIL to enhance the extrinsic apoptotic pathway. We focus on the main signaling channels involved, such as the endoplasmic reticulum (ER) stress-mediated apoptosis, extrinsic death receptor, and intrinsic mitochondrial pathways. The review explores the role of natural substances such as polyphenols, terpenoids, alkaloids, and flavonoids in promoting apoptotic cell death and increasing cancer cell susceptibility, potentially aiding in cancer treatments and the potential of combining natural products with traditional chemotherapeutic medicines to combat medication resistance and enhance therapeutic efficacy. Understanding cancer development involves inhibiting cell proliferation, regulating it, targeting apoptosis pathways, and using plant and marine extracts as apoptotic inducers.

Natural substances derived from herbs or plants are promising sources of anticancer agents against colorectal cancer via triggering apoptosis

OBJECTIVES

Nowadays, one of the most common gastrointestinal cancers is colorectal cancer (CRC). Chemotherapy is still one of the main methods to treat cancer. However, the currently available synthetic chemotherapy drugs often cause serious adverse reactions. Apoptosis is generally considered as an ideal way for induction the death of tumour cells without the body's inflammatory response, and it is reported that lots of natural agents could trigger various cancer cells to apoptosis. The overarching aim of this project was to elucidate the specific mechanisms by which natural substances induce apoptosis in CRC cells and to be used as an alternative therapeutic option in the future.

KEY FINDINGS

The mechanisms for the pro-apoptotic effects of natural substances derived from herbs or plants include death receptor pathway, mitochondrial pathway, endoplasmic reticulum stress pathway, related signal transduction pathways (PI3K/Akt, MAPK, p53 signalling), and so on.

SUMMARY

This paper updated this information regarding the anti-tumour effects of natural agents via induction of apoptosis against CRC, which would be beneficial for future new drug research regarding natural products from herbs or plants.

Effects of Holothurian Glycosaminoglycan on the Sensitivity of Lung Cancer to Chemotherapy

Sea cucumber is a kind of food. Holothurian glycosaminoglycan (hGAG) is extracted from the body wall of the sea cucumber. Administration of hGAG and cisplatin (DDP) together to treat lung cancer was investigated. Lung adenocarcinoma A549 cells were cultured and divided into 4 groups: control group, hGAG 100 µg/mL group, DDP 3 µg/mL group, and hGAG 100 µg/mL + DDP 3 µg/mL group. Cell inhibition and apoptosis was evaluated by CCK8 and Hoechst33258 staining. Cell cycle was tested by Annexin V-FITC/PI (propidium iodide) double-staining and flow cytometry. The expression of mRNA and protein of Bcl-2, Bax, caspase-3, and survivin were detected by reverse transcriptase-polymerase chain reaction and Western blot, respectively. The results showed that hGAG combined with DDP enhanced the inhibitory effect of DDP on A549 lung cells through apoptosis pathway. The mechanism of apoptosis may be related to the reduction of Bcl-2 and survivin, as well as the ascension of Bax and caspase-3. hGAG could promote A549 cell cycle arrest in G1 and G2 phase and improve the DDP chemotherapy effects on A549 cells.

Medicinal Plants in the Prevention and Treatment of Colon Cancer

The standard treatment for cancer is generally based on using cytotoxic drugs, radiotherapy, chemotherapy, and surgery. However, the use of traditional treatments has received attention in recent years. The aim of the present work was to provide an overview of medicinal plants effective on colon cancer with special emphasis on bioactive components and underlying mechanisms of action. Various literature databases, including Web of Science, PubMed, and Scopus, were used and English language articles were considered. Based on literature search, 172 experimental studies and 71 clinical cases on 190 plants were included. The results indicate that grape, soybean, green tea, garlic, olive, and pomegranate are the most effective plants against colon cancer. In these studies, fruits, seeds, leaves, and plant roots were used for in vitro and in vivo models. Various anticolon cancer mechanisms of these medicinal plants include induction of superoxide dismutase, reduction of DNA oxidation, induction of apoptosis by inducing a cell cycle arrest in S phase, reducing the expression of PI3K, P-Akt protein, and MMP as well; reduction of antiapoptotic Bcl-2 and Bcl-xL proteins, and decrease of proliferating cell nuclear antigen (PCNA), cyclin A, cyclin D1, cyclin B1 and cyclin E. Plant compounds also increase both the expression of the cell cycle inhibitors p53, p21, and p27, and the BAD, Bax, caspase 3, caspase 7, caspase 8, and caspase 9 proteins levels. In fact, purification of herbal compounds and demonstration of their efficacy in appropriate in vivo models, as well as clinical studies, may lead to alternative and effective ways of controlling and treating colon cancer.

Apoptotic Induction and Anti-Migratory Effects of Rhazya Stricta Fruit Extracts on a Human Breast Cancer Cell Line

Rhazya stricta is a medicinal plant that is widely used in Saudi folklore medicine for treatment of various diseases. R. stricta fruit powder was sequentially extracted with n-hexane, chloroform, ethyl acetate, and methanol using a Soxhlet extractor. The cytotoxic effects of these fractions on human breast cancer cells (MDA-MB-231 and MCF-7) and non-tumorigenic control cells (MCF-10A) were evaluated via cell viability measurements, microscopy, gene expression, and migration assays. Moreover, the effect of the most promising extract on 7,12-dimethyl-benz[a]anthracene (DMBA)-induced breast cancer was investigated in rats. The promising extract was also subjected to gas chromatography–mass spectrometry. Fruit extracts of R. stricta were significantly cytotoxic toward all tested cell lines, as demonstrated by MTT and LDH assays. Treatment of MDA-MB-231 cells with fruit ethyl acetate fraction (RSF EtOAc) increased expression 11of P53, Bax and activation of caspase 3/7. A cell migration scratch assay demonstrated that extracts at non-cytotoxic concentrations exerted a potent anti-migration activity against the highly invasive MDA-MB-231 cell line. Moreover, RT-PCR results showed that RSF EtOAc significantly downregulated MMP-2 and MMP-9 expression, which play an important role in breast cancer metastasis. Histological studies of breast tissue in experimental animals showed a slight improvement in tissue treated with fruit ethyl acetate extract. GC-MS chromatogram showed thirteen peaks with major constituents were camphor, trichosenic acid and guanidine. Our current study demonstrates that fruit extracts of R. stricta are cytotoxic toward breast cancer cell lines through apoptotic mechanisms.

Cardamonin reduces chemotherapy resistance of colon cancer cells via the TSP50/NF-κB pathway in vitro

It has previously been reported that cardamonin is able to regulate glycometabolism and vasodilation whilst also exhibiting anti-inflammatory and antitumor properties. The antitumor effect of cardamonin is multifaceted, and so it is necessary to investigate the antitumor mechanisms of cardamonin at the molecular level. Cardamonin alters chemotherapy-resistant colon cancer cell growth; however, the underlying mechanism is unknown. The present study was conducted to investigate the effect of cardamonin on chemotherapy-resistant colon cancer cells and the possible mechanisms of action. Cardamonin significantly suppressed the growth of chemotherapy-resistant colon cancer cells, induced apoptosis and promoted caspase-3/9 activity and Bax protein expression in 5-fluorouracil (5-FU)-resistant HCT-116 cells. Cardamonin significantly suppressed c-MYC, octamer-binding transcription factor 4, cyclin E, testes-specific protease 50 and nuclear factor-κB protein expression in 5-FU-resistant HCT-116 cells. The findings of the present study demonstrate that cardamonin suppresses chemotherapy-colon cancer cell via the NF-κB pathway in vitro.

Targeting activator protein 1 signaling pathway by bioactive natural agents: Possible therapeutic strategy for cancer prevention and intervention

Activator protein 1 (AP-1) is a key transcription factor in the control of several cellular processes responsible for cell survival proliferation and differentiation. Dysfunctional AP-1 expression and activity are involved in several severe diseases, especially inflammatory disorders and cancer. Therefore, targeting AP-1 has recently emerged as an attractive therapeutic strategy for cancer prevention and therapy. This review summarizes our current understanding of AP-1 biology and function as well as explores and discusses several natural bioactive compounds modulating AP-1-associated signaling pathways for cancer prevention and intervention. Current limitations, challenges, and future directions of research are also critically discussed.