Natural Products in Preventing Tumor Drug Resistance and Related Signaling Pathways.

Drug resistance is still an obstacle in cancer therapy, leading to the failure of tumor treatment. The emergence of tumor drug resistance has always been a main concern of oncologists. Therefore, overcoming tumor drug resistance and looking for new strategies for tumor treatment is a major focus in the field of tumor research. Natural products serve as effective substances against drug resistance because of their diverse chemical structures and pharmacological effects. We reviewed the signaling pathways involved in the development of tumor drug resistance, including Epidermal growth factor receptor (EGFR), Renin-angiotensin system (Ras), Phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt), Wnt, Notch, Transforming growth factor-beta (TGF-ß), and their specific signaling pathway inhibitors derived from natural products. This can provide new ideas for the prevention of drug resistance in cancer therapy.

Label-free-based quantitative proteomic analysis of the inhibition of cisplatin-resistant ovarian cancer cell proliferation by cucurbitacin B.

BACKGROUND: Ovarian cancer is a serious threat to women's health, and resistance to chemotherapeutic drugs constitutes one of the principal reasons for ovarian cancer recurrence and the low overall survival rate. Therefore, it is of paramount importance to develop additional and more-effective drugs to combat resistance to chemotherapeutic drugs. Cucurbitacin B (CuB) is a natural compound found in food plants such as bitter gourd and pumpkin, and it manifests favorable antitumor effects on a variety of malignant tumors. PURPOSE: The present study aimed to determine the mechanism effects of CuB overcomes tumor-drug resistance in ovarian cancer. METHODS: We used CCK-8, Edu, flow cytometric assays and cisplatin-resistant ovarian cancer xenograft mouse model to evaluate the cellular proliferation, cellular apoptosis.and tumor growth. We subsequently applied a pharmacoproteomic approach to analyze the molecular mechanisms by which CuB inhibited the proliferation of cisplatin-resistant ovarian cancer cells. We also employed western blot and molecular docking experiments to verify elements of PI3K/Akt/mTOR pathway expression. RESULTS: We found that CuB inhibited cellular proliferation and promoted apoptosis in cisplatin-resistant ovarian cancer cell lines. We discerned that CuB inhibited tumor growth of xenograft mouse tumors. We ascertained that treatment of A2780-DDP cells with CuB resulted in the differential expression of 305 proteins, with 202 proteins downregulated and 103 proteins upregulated. Of these proteins, the mTOR protein was significantly downregulated in the drug-treated group. We also found that CuB inhibited PI3K, Akt, and mTOR and that it activated cGAS expression upstream of PI3K and inhibited ATR expression. Molecular docking experiments revealed that CuB was hydrogen-bonded to mTOR proteins at Gly (2142) and Thr (2207), with a binding force of -10.2 kcal/mol. CONCLUSION: Our study confirmed that cucurbitacin B inhibits the PI3K/Akt/mTOR signaling pathway, targets mTOR, suppresses the proliferation of cisplatin-resistant ovarian cancer cells.And we also found that cucurbitacin B induces DNA damage, activates cGASA and recruits IKBα,playing a crucial role in eliciting anti-tumor immunity. We herein uncovered a new use for CuB in inhibiting tumor-drug resistance, providing a novel approach to overcoming chemotherapeutic drug resistance in ovarian cancer.

Human microbiomes in cancer development and therapy.

Colonies formed by bacteria, archaea, fungi, and viral groups and their genomes, metabolites, and expressed proteins constitute complex human microbiomes. An increasing evidences showed that carcinogenesis and disease progression were link to microbiomes. Different organ sources, their microbial species, and their metabolites are different; the mechanisms of carcinogenic or procancerous are also different. Here, we summarize how microbiomes contribute to carcinogenesis and disease progression in cancers of the skin, mouth, esophagus, lung, gastrointestinal, genital, blood, and lymph malignancy. We also insight into the molecular mechanisms of triggering, promoting, or inhibiting carcinogenesis and disease progress induced by microbiomes or/and their secretions of bioactive metabolites. And then, the strategies of application of microorganisms in cancer treatment were discussed in detail. However, the mechanisms by which human microbiomes function are still poorly understood. The bidirectional interactions between microbiotas and endocrine systems need to be clarified. Probiotics and prebiotics are believed to benefit human health via a variety of mechanisms, in particular, in tumor inhibition. It is largely unknown how microbial agents cause cancer or how cancer progresses. We expect this review may open new perspectives on possible therapeutic approaches of patients with cancer.