Radiosensitizing effects of trabectedin on human A549 lung cancer cells and HT-29 colon cancer cells

Trabectedin and Lurbinectedin Modulate the Interplay between Cells in the Tumour Microenvironment-Progresses in Their Use in Combined Cancer Therapy

Trabectedin (TRB) and Lurbinectedin (LUR) are alkaloid compounds originally isolated from Ecteinascidia turbinata with proven antitumoral activity. Both molecules are structural analogues that differ on the tetrahydroisoquinoline moiety of the C subunit in TRB, which is replaced by a tetrahydro-β-carboline in LUR. TRB is indicated for patients with relapsed ovarian cancer in combination with pegylated liposomal doxorubicin, as well as for advanced soft tissue sarcoma in adults in monotherapy. LUR was approved by the FDA in 2020 to treat metastatic small cell lung cancer. Herein, we systematically summarise the origin and structure of TRB and LUR, as well as the molecular mechanisms that they trigger to induce cell death in tumoral cells and supporting stroma cells of the tumoral microenvironment, and how these compounds regulate immune cell function and fate. Finally, the novel therapeutic venues that are currently under exploration, in combination with a plethora of different immunotherapeutic strategies or specific molecular-targeted inhibitors, are reviewed, with particular emphasis on the usage of immune checkpoint inhibitors, or other bioactive molecules that have shown synergistic effects in terms of tumour regression and ablation. These approaches intend to tackle the complexity of managing cancer patients in the context of precision medicine and the application of tailor-made strategies aiming at the reduction of undesired side effects.

Radiosensitizing Effect of Trabectedin on Human Soft Tissue Sarcoma Cells

Trabectedin is used for the treatment of advanced soft tissue sarcomas (STSs). In this study, we evaluated if trabectedin could enhance the efficacy of irradiation (IR) by increasing the intrinsic cell radiosensitivity and modulating tumor micro-environment in fibrosarcoma (HS 93.T), leiomyosarcoma (HS5.T), liposarcoma (SW872), and rhabdomyosarcoma (RD) cell lines. A significant reduction in cell surviving fraction (SF) following trabectedin + IR compared to IR alone was observed in liposarcoma and leiomyosarcoma (enhancement ratio at 50%, ER50: 1.45 and 2.35, respectively), whereas an additive effect was shown in rhabdomyosarcoma and fibrosarcoma. Invasive cells' fraction significantly decreased following trabectedin ± IR compared to IR alone. Differences in cell cycle distribution were observed in leiomyosarcoma and rhabdomyosarcoma treated with trabectedin + IR. In all STS lines, trabectedin + IR resulted in a significantly higher number of γ-H2AX (histone H2AX) foci 30 min compared to the control, trabectedin, or IR alone. Expression of ATM, RAD50, Ang-2, VEGF, and PD-L1 was not significantly altered following trabectedin + IR. In conclusion, trabectedin radiosensitizes STS cells by affecting SF (particularly in leiomyosarcoma and liposarcoma), invasiveness, cell cycle distribution, and γ-H2AX foci formation. Conversely, no synergistic effect was observed on DNA damage repair, neoangiogenesis, and immune system.

Pepper Alkaloid Piperine Increases Radiation Sensitivity of Cancer Cells from Glioblastoma and Hypopharynx In Vitro

In our study, our aim was to examine the cytotoxic and radio-sensitizing effect of the alkaloid piperine, a major pungent of black pepper, on two different human epithelial tumor cell lines in vitro. The growth of the human cell lines T98G (glioblastoma) and FaDu (hypopharyngeal carcinoma) was examined under the influence of piperine in different concentrations. In addition, after combined treatment with ionizing radiation, long-term survival was investigated with a colony formation assay. The proliferation was analyzed using the BrdU-assay, while the DNA repair capacity was examined via the γH2AX assay. Piperine reduced the growth of both cell lines in a concentration-dependent manner as well as a time-dependent one. After combined treatment with piperine and ionizing radiation, an inhibition of clonogenic survival could be proven. A reduced proliferation capacity and an additive effect on DNA damage 24 h after irradiation are possible causal mechanisms, which were also demonstrated for both cell lines. Based on the results presented in this study, piperine was shown to have cytotoxic antitumor activity and a radio-sensitizing effect in micromolar concentrations in the human tumor cells that were tested. Based on these results piperine represents a potential therapeutic option in radio-oncological treatment.

Trabectedin Plus Radiotherapy for Advanced Soft-Tissue Sarcoma: Experience in Forty Patients Treated at a Sarcoma Reference Center

Simple Summary

Active therapeutic options in advanced sarcomas, able to induce durable objective responses, are scarce beyond first line. New strategies for disease and symptomatic control are thus needed. Our aim was to analyze the activity of the combination of trabectedin and palliative radiotherapy in the real-life setting, in patients with pretreated metastatic sarcoma. Our findings on 40 pretreated metastatic soft-tissue sarcoma patients, in terms of objective responses (overall response rate by RECIST of 32.5%) and outcome (median progression-free survival of 7.5 months and median overall survival of 23.5 months), confirm the activity of this regimen, which is a valuable option to consider, especially in patients in which a dimensional response could help for symptomatic control.

Abstract

Symptomatic control and tumoral shrinkage is an unmet need in advanced soft-tissue sarcoma (STS) patients beyond first-line. The combination of trabectedin and radiotherapy showed activity in a recently reported clinical trial in this setting. This retrospective series aims to analyze our experience with the same regimen in the real-life setting. We retrospectively reviewed advanced sarcoma patients treated with trabectedin concomitantly with radiotherapy with palliative intent. Growth-modulation index (GMI) was calculated as a surrogate of efficacy. Forty metastatic patients were analyzed. According to RECIST, there was one (2.5%) complete response, 12 (30%) partial responses, 18 (45%) disease stabilizations, and nine (22.5%) progressions. After a median follow-up of 15 months (range 2–38), median progression-free survival (PFS) and overall survival (OS) were 7.5 months (95% CI 2.8–12.2) and 23.5 months (95% CI 1.1–45.8), respectively. Median GMI was 1.42 (range 0.19–23.76), and in 16 (53%) patients, it was >1.33. In patients with GMI >1.33, median OS was significantly longer than in those with GMI 0–1.33 (median OS 52.1 months (95% CI not reached) vs. 8.9 months (95% CI 6.3–11.6), p = 0.028). The combination of trabectedin plus radiotherapy is an active therapeutic option in patients with advanced STS, especially when tumor shrinkage for symptomatic relief is needed.

The solvent and treatment regimen of sodium selenite cause its effects to vary on the radiation response of human bronchial cells from tumour and normal tissues

Sodium selenite is often given to moderate the side effects of cancer therapy to enhance the cellular defence of non-cancerous cells. To determine whether sodium selenite during radiotherapy protects not only normal cells but also cancer cells, which would imply a reduction of the desired effect of irradiation on tumour during radiotherapy, the effect of the combined treatment of irradiation and sodium selenite was investigated. Human bronchial cells from carcinoma (A549) and normal tissue (BEAS-2B) were treated with sodium selenite and effects on growth and in combination with radiation on metabolic activity and cell cycle distribution were studied. The influence on radiosensitivity was determined via colony forming assays using different solvents of sodium selenite and treatment schedules. It was shown that sodium selenite inhibits growth and influences cell cycle distribution of both normal and tumour cells. Metabolic activity of normal cells decreased more rapidly compared to that of cancer cells. The influence of sodium selenite on radiation response depended on the different treatment schedules and was strongly affected by the solvent of the agent. It could be shown that the effect of sodium selenite on radiation response is strongly dependent on the respective experimental in vitro conditions and ranges from lead to an initially suspected but ultimately no real radioprotection to radiosensitizing up to no effect in one and the same cell line. This might be a reason for controversially described cell responses to radiation under the influence of sodium selenite in studies so far.

Discovery of oxyepiberberine as a novel tubulin polymerization inhibitor and an anti-colon cancer agent against LS-1034 cells

Coptis chinensis Franch. has been extensively used in traditional Chinese medicine. The chemical structure of oxyepiberberine, as an alkaloid isolated from Coptis chinensis Franch., has been previously studied. However, anti-cancer effects and underlying mechanisms of oxyepiberberine need to be explored. This study aimed to investigate the anti-cancer effects and underlying mechanisms of oxyepiberberine on LS-1034 human colon cancer cells. The anti-proliferative effects of six derivatives of oxyepiberberine on colon cancer cells were assessed. Among six derivatives, oxyepiberberine showed the greatest anti-proliferative effect on LS-1034 cells with an IC₅₀ value of 1.36 μM. Oxyepiberberine also induced apoptosis and inhibited migration of LS-1034 cells in a concentration-dependent manner. Importantly, oxyepiberberine was identified as a potent tubulin polymerization inhibitor. The tubulin polymerization inhibitory effects of oxyepiberberine in a concentration-dependent manner with an IC₅₀ value of 1.26 μM were observed. A xenograft mouse model of colon cancer showed that oxyepiberberine could suppress tumor growth without an obvious toxicity. Conclusion Oxyepiberberine was found as a novel tubulin polymerization inhibitor, and it could be a promising agent to treat colon cancer.