Jadomycins: A potential chemotherapy for multi-drug resistant metastatic breast cancer

Understanding Cancer's Defense against Topoisomerase-Active Drugs: A Comprehensive Review

In recent years, the emergence of cancer drug resistance has been one of the crucial tumor hallmarks that are supported by the level of genetic heterogeneity and complexities at cellular levels. Oxidative stress, immune evasion, metabolic reprogramming, overexpression of ABC transporters, and stemness are among the several key contributing molecular and cellular response mechanisms. Topo-active drugs, e.g., doxorubicin and topotecan, are clinically active and are utilized extensively against a wide variety of human tumors and often result in the development of resistance and failure to therapy. Thus, there is an urgent need for an incremental and comprehensive understanding of mechanisms of cancer drug resistance specifically in the context of topo-active drugs. This review delves into the intricate mechanistic aspects of these intracellular and extracellular topo-active drug resistance mechanisms and explores the use of potential combinatorial approaches by utilizing various topo-active drugs and inhibitors of pathways involved in drug resistance. We believe that this review will help guide basic scientists, pre-clinicians, clinicians, and policymakers toward holistic and interdisciplinary strategies that transcend resistance, renewing optimism in the ongoing battle against cancer.

Anti-breast cancer-induced cardiomyopathy: Mechanisms and future directions

With the progression of tumor treatment, the 5-year survival rate of breast cancer is close to 90%. Cardiovascular toxicity caused by chemotherapy has become a vital factor affecting the survival of patients with breast cancer. Anthracyclines, such as doxorubicin, are still some of the most effective chemotherapeutic agents, but their resulting cardiotoxicity is generally considered to be progressive and irreversible. In addition to anthracyclines, platinum- and alkyl-based antitumor drugs also demonstrate certain cardiotoxic effects. Targeted drugs have always been considered a relatively safe option. However, in recent years, some random clinical trials have observed the occurrence of subclinical cardiotoxicity in targeted antitumor drug users, which may be related to the effects of targeted drugs on the angiotensin converting enzyme, angiotensin receptor and β receptor. The use of angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers and beta-blockers may prevent clinical cardiotoxicity. This article reviews the toxicity and mechanisms of current clinical anti-breast cancer drugs and proposes strategies for preventing cardiovascular toxicity to provide recommendations for the clinical prevention and treatment of chemotherapy-related cardiomyopathy.

Bufalin reverses ABCB1-mediated resistance to docetaxel in breast cancer

Background

Docetaxel (DCT) is widely used in clinical practice, but the drug resistance of breast cancer patients has become an important reason to limit its clinical efficacy. Chan'su is a commonly used traditional Chinese medicine for the treatment of breast cancer. Bufalin (BUF) is a bioactive polyhydroxy steroid extracted from chan'su and has strong antitumor activity, but there are few studies on reversing drug resistance in breast cancer. The aim of this study is to determine whether BUF can reverse the drug resistance to DCT and restore efficacy in breast cancer.

Methodology

The reversal index of BUF was detected by Cell Counting Kit-8 (CCK-8) assays. The effects of BUF on enhancing the apoptosis of DCT were detected by flow cytometry and Western Blot (WB), and the main differential expression levels of sensitive and resistant strains were detected by high-throughput sequencing. Rhodamine 123 assay, WB and ATP Binding Cassette Subfamily B Member 1 (ABCB1) ATPase activity experiments were used to detect the effect of BUF on ABCB1. The nude mouse orthotopic model was constructed to investigate the reversal effect of BUF on DCT resistance in vivo.

Results

With BUF intervention, the sensitivity of drug-resistant cell lines to DCT was increased. BUF can inhibit the expression of ABCB1 protein, increase the drug accumulation of DCT in drug-resistant strains, and reduce the ATPase activity of ABCB1. Animal experiments show that BUF can inhibit the growth of drug-resistant tumors in an orthotopic model of breast cancer and decrease the expression of ABCB1.

Conclusion

BUF can reverse ABCB1-mediated docetaxel resistance in breast cancer.

Synthesis and in Vitro Cytotoxicity Evaluation of Jadomycins

Jadomycins, which are benzo[b]phenanthridine-type alkaloids isolated from Streptomyces venezuelae ISP5230, exhibit cytotoxic activity against multidrug-resistant breast cancer cells. We have previously achieved the total synthesis of jadomycins using the direct arylation of juglone as a key step. In this study, we achieved the total synthesis of jadomycin T and jadomycin aglycons using L-threonine and 1-amino-2-propanol as nitrogen sources. Additionally, we evaluated the cytotoxic activity of eight compounds, including glycosides, jadomycin T, and their corresponding aglycons, in eight types of tumor cells. The evaluated jadomycins tended to exhibit stronger cytotoxic activity as aglycons than as glycosides. Although the presence of a 1,3-oxazolidine ring derived from an amino acid was not essential, the presence of the 1,3-oxazolidine ring showed strong activity when the ring had a carboxyl group. Furthermore, compared to the non-natural isomer at a different position on the phenolic hydroxyl group, the naturally occurring phenanthroviridin aglycon exhibited stronger cytotoxic activity. In addition, this study suggests that jadomycins may become lead compounds for the treatment of brain tumors; however, further studies on their ability to penetrate the blood-brain barrier are required.

Pilot study of jadomycin B pharmacokinetics and anti-tumoral effects in zebrafish larvae and mouse breast cancer xenograft models

Despite numerous therapeutic options, multidrug resistance (MDR) remains an obstacle to successful breast cancer therapy. Jadomycin B, a natural product derived from Streptomyces venezuelae ISP5230, maintains cytotoxicity in MDR human breast cancer cells. Our objectives were to evaluate the pharmacokinetics, toxicity, anti-tumoral, and anti-metastatic effects of jadomycin B in zebrafish larvae and mice. In a zebrafish larval xenograft model, jadomycin B significantly reduced the proliferation of human MDA-MB-231 cells at or below its maximum tolerated dose (40 µm). In female Balb/C mice, a single intraperitoneal dose (6 mg/kg) was rapidly absorbed with a maximum serum concentration of 3.4 ± 0.27 µm. Jadomycin B concentrations declined biphasically with an elimination half-life of 1.7 ± 0.058 h. In the 4T1 mouse mammary carcinoma model, jadomycin B (12 mg/kg every 12 h from day 6 to 15 after tumor cell injection) decreased primary tumor volume compared to vehicle control. Jadomycin B-treated mice did not exhibit weight loss, nor significant increases in biomarkers of impaired hepatic (alanine aminotransferase) and renal (creatinine) function. In conclusion, jadomycin B demonstrated a good safety profile and provided partial anti-tumoral effects, warranting further dose-escalation safety and efficacy studies in MDR breast cancer models.

Overexpression of satellite RNAs in heterochromatin induces chromosomal instability and reflects drug sensitivity in mouse cancer cells

Overexpression of satellite RNAs in heterochromatin induces chromosomal instability (CIN) through the DNA damage response and cell cycle checkpoint activation. Although satellite RNAs may be therapeutic targets, the associated mechanisms underlying drug sensitivity are unknown. Here, we determined whether satellite RNAs reflect drug sensitivity to the topoisomerase I inhibitor camptothecin (CPT) via CIN induction. We constructed retroviral vectors expressing major satellite and control viruses, infected microsatellite stable mouse colon cancer cells (CT26) and MC38 cells harboring microsatellite instability, and assessed drug sensitivity after 48 h. Cells overexpressing satellite RNAs showed clear features of abnormal segregation, including micronuclei and anaphase bridging, and elevated levels of the DNA damage marker γH2AX relative to controls. Additionally, overexpression of satellite RNAs enhanced MC38 cell susceptibility to CPT [half-maximal inhibitory concentration: 0.814 μM (control) vs. 0.332 μM (MC38 cells with a major satellite), p = 0.003] but not that of CT26. These findings imply that MC38 cells, which are unlikely to harbor CIN, are more susceptible to CIN-induced CPT sensitivity than CT26 cells, which are characterized by CIN. Furthermore, CPT administration upregulated p53 levels but not those of p21, indicating that overexpression of major satellite transcripts likely induces CPT-responsive cell death rather than cellular senescence.

Preparation of 2-Methoxyestradiol Self-emulsified Drug Delivery System and the Effect on Combination Therapy with Doxorubicin Against MCF-7/ADM Cells

Due to the poor solubility and bioavailability of 2-methoxyestradiol (2-ME), 2-ME emulsified drug delivery system (2-ME-SEDDS) was designed and characterized. After dilution with 5% glucose, 2-ME-SEDDS formed fine emulsions with mean diameter of 171 ± 14 nm and zeta potential of - 7.4 ± 0.6 mV. The cytotoxicity of 2-ME-SEDDS against MCF-7 and MCF-7/ADM cells was considerable to that of free 2-ME, and the half maximal inhibitory concentration ran up to 195 µg/mL on MCF-7/ADM cells. In order to gain a satisfactory inhibition effect on MCF-7/ADM cells, 2-ME-SEDDS combined with doxorubicin was used. It is worth noting that the combination of 2-ME-SEDDS and doxorubicin displayed a superior synergistic effect with a combined index of 0.62. And the cellular uptake of doxorubicin by MCF-7/ADM cells in the combination group was significantly higher than that of doxorubicin treatment group. The study preliminarily suggested that 2-ME-SEDDS could increase the cellular uptake of doxorubicin by MCF-7/ADM cells and the synergistic effect may be attributed to the increased cellular uptake of doxorubicin under the influence of 2-ME-SEDDS. In conclusion, SEDDS was an alternative and promising formulation for 2-ME. The combination therapy with synergistic effect by the combination of 2-ME-SEDDS and doxorubicin seems to be a promising strategy to potentiate anti-tumor efficiency against MCF-7/ADM, even other multidrug resistance tumors.