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p53 Status does not affect photodynamic cell killing induced by hypericin

Lee HB, Ho AS, Teo SH

Cancer Chemother Pharmacol, 2006 Jul;58(1):91-8.
PMID: 16211395

Given that p53 is a tumor suppressor that plays a central role in the cellular response to DNA damage and that more than 50% of all cancers have mutated p53, the wider utility of photodynamic therapy (PDT) in the treatment of cancer will depend on an understanding of whether p53 status modulates response to PDT. In this study, we investigated the photosensitivity of isogenic cell lines that differ only in their p53 status to PDT using hypericin as the photosensitizer.

Matched MeSH terms: Radiation-Sensitizing Agents/pharmacokinetics; Radiation-Sensitizing Agents/pharmacology*
The combination of histone deacetylase inhibitors and radiotherapy: a promising novel approach for cancer treatment

Shirbhate E, Patel P, Patel VK, Veerasamy R, Sharma PC, Rajak H

Future Oncol, 2020 Oct;16(30):2457-2469.
PMID: 32815411 DOI: 10.2217/fon-2020-0385

HDAC inhibitors (HDACi) play an essential role in various cellular processes, such as differentiation and transcriptional regulation of key genes and cytostatic factors, cell cycle arrest and apoptosis that facilitates the targeting of epigenome of eukaryotic cells. In the majority of cancers, only a handful of patients receive optimal benefit from chemotherapeutics. Additionally, there is emerging interest in the use of HDACi to modulate the effects of ionizing radiations. The use of HDACi with radiotherapy, with the goal of reaching dissimilar, often distinct pathways or multiple biological targets, with the expectation of synergistic effects, reduced toxicity and diminished intrinsic and acquired resistance, conveys an approach of increasing interest. In this review, the clinical potential of HDACi in combination with radiotherapy is described as an efficient synergy for cancer treatment will be overviewed.

Matched MeSH terms: Radiation-Sensitizing Agents/administration & dosage; Radiation-Sensitizing Agents/therapeutic use
Fulltext Radiosensitization Effects by Bismuth Oxide Nanoparticles in Combination with Cisplatin for High Dose Rate Brachytherapy

Sisin NNT, Abdul Razak K, Zainal Abidin S, Che Mat NF, Abdullah R, Ab Rashid R, et al.

Int J Nanomedicine, 2019;14:9941-9954.
PMID: 31908451 DOI: 10.2147/IJN.S228919

Purpose: The aim of this study was to investigate the potential of the synergetic triple therapeutic combination encompassing bismuth oxide nanoparticles (BiONPs), cisplatin (Cis), and high dose rate (HDR) brachytherapy with Ir-192 source in breast cancer and normal fibroblast cell line.
Methods: In vitro models of breast cancer cell lines (MCF-7, MDA-MB-231) and normal fibroblast cell line (NIH/3T3) were employed. Cellular localization and cytotoxicity studies were conducted prior to inspection on the radiosensitization effects and generation of reactive oxygen species (ROS) on three proposed radiosensitizers: BiONPs, Cis, and BiONPs-Cis combination (BC). The optimal, non-cytotoxic concentration of BiONPs (0.5 mM) and the 25% inhibitory concentration of Cis (1.30 µM) were applied. The radiosensitization effects were evaluated by using a 0.38 MeV Iridium-192 HDR brachytherapy source over a prescribed dose range of 0 Gy to 4 Gy.
Results: The cellular localization of BiONPs was visualized by light microscopy and accumulation of the BiONPs within the vicinity of the nuclear membrane was observed. Quantification of the sensitization enhancement ratio extrapolated from the survival curves indicates radiosensitization effects for MCF-7 and MDA-MB-231 when treated with BiONPs, Cis, and BC. However, NIH/3T3 cells exhibited contradictive behavior as it only reacted towards the BC combination. Nonetheless, the MCF-7 cell line loaded with BC shows the highest SER of 4.29. ROS production analysis, on the other hand, shows that Cis and BC radiosensitizers generated the highest free radicals in comparison to BiONPs alone.
Conclusion: A BiONPs-Cis combination was unveiled as a novel approach that offers promising radiosensitization enhancement that will increase the efficiency of tumor control while preserving the normal tissue at a reduced dose. This data is the first precedent to prove the synergetic implication of BiONPs, Cis, and HDR brachytherapy that will be beneficial for future chemoradiotherapy strategies in cancer care.

Matched MeSH terms: Radiation-Sensitizing Agents/administration & dosage; Radiation-Sensitizing Agents/pharmacology*
Fulltext Synergetic Influence of Bismuth Oxide Nanoparticles, Cisplatin and Baicalein-Rich Fraction on Reactive Oxygen Species Generation and Radiosensitization Effects for Clinical Radiotherapy Beams

Talik Sisin NN, Abdul Razak K, Zainal Abidin S, Che Mat NF, Abdullah R, Ab Rashid R, et al.

Int J Nanomedicine, 2020;15:7805-7823.
PMID: 33116502 DOI: 10.2147/IJN.S269214

Purpose: This study aimed to quantify synergetic effects induced by bismuth oxide nanoparticles (BiONPs), cisplatin (Cis) and baicalein-rich fraction (BRF) natural-based agent on the reactive oxygen species (ROS) generation and radiosensitization effects under irradiation of clinical radiotherapy beams of photon, electron and HDR-brachytherapy. The combined therapeutic responses of each compound and clinical radiotherapy beam were evaluated on breast cancer and normal fibroblast cell line.
Methods: In this study, individual BiONPs, Cis, and BRF, as well as combinations of BiONPs-Cis (BC), BiONPs-BRF (BB) and BiONPs-Cis-BRF (BCB) were treated to the cells before irradiation using HDR brachytherapy with 0.38 MeV iridium-192 source, 6 MV photon beam and 6 MeV electron beam. The individual or synergetic effects from the application of the treatment components during the radiotherapy were elucidated by quantifying the ROS generation and radiosensitization effects on MCF-7 and MDA-MB-231 breast cancer cell lines as well as NIH/3T3 normal cell line.
Results: The ROS generated in the presence of Cis stimulated the most substantial amount of ROS compared to the BiONPs and BRF. Meanwhile, the combination of the components had induced the higher ROS levels for photon beam than the brachytherapy and electron beam. The highest ROS enhancement relative to the control is attributable to the presence of BC combination in MDA-MB-231 cells, in comparison to the BB and BCB combinations. The radiosensitization effects which were quantified using the sensitization enhancement ratio (SER) indicate the highest value by BC in MCF-7 cells, followed by BCB and BB treatment. The radiosensitization effects are found to be more prominent for brachytherapy in comparison to photon and electron beam.
Conclusion: The BiONPs, Cis and BRF are the potential radiosensitizers that could improve the efficiency of radiotherapy to eradicate the cancer cells. The combination of these potent radiosensitizers might produce multiple effects when applied in radiotherapy. The BC combination is found to have the highest SER, followed by the BCB combination. This study is also the first to investigate the effect of BRF in combination with BiONPs (BB) and BC (BCB) treatments.

Matched MeSH terms: Radiation-Sensitizing Agents/pharmacology
Fulltext Cytotoxic and radiosensitising effects of a novel thioredoxin reductase inhibitor in breast cancer

Abdullah NA, Inman M, Moody CJ, Storr SJ, Martin SG

Invest New Drugs, 2021 10;39(5):1232-1241.
PMID: 33768386 DOI: 10.1007/s10637-021-01106-5

Radiotherapy is an effective treatment modality for breast cancer but, unfortunately, not all patients respond fully with a significant number experiencing local recurrences. Overexpression of thioredoxin and thioredoxin reductase has been reported to cause multidrug and radiation resistance - their inhibition may therefore improve therapeutic efficacy. Novel indolequinone compounds have been shown, in pancreatic cancer models, to inhibit thioredoxin reductase activity and exhibit potent anticancer activity. The present study evaluates, using in vitro breast cancer models, the efficacy of a novel indolequinone compound (IQ9) as a single agent and in combination with ionising radiation using a variety of endpoint assays including cell proliferation, clonogenic survival, enzyme activity, and western blotting. Three triple-negative breast cancer (MDA-MB-231, MDA-MB-468, and MDA-MB-436) and two luminal (MCF-7 and T47D) breast cancer cell lines were used. Results show that treatment with IQ9 significantly inhibited thioredoxin reductase activity, and inhibited cell growth and colony formation of breast cancer cells with IC50 values in the low micromolar ranges. Enhanced radiosensitivity of triple-negative breast cancer cells was observed, with sensitiser enhancement ratios of 1.20-1.43, but with no evident radiosensitisation of luminal breast cancer cell lines. IQ9 upregulated protein expression of thioredoxin reductase in luminal but not in triple-negative breast cancer cells which may explain the observed differential radiosensitisation. This study provides important evidence of the roles of the thioredoxin system as an exploitable radiobiological target in breast cancer cells and highlights the potential therapeutic value of indolequinones as radiosensitisers.***This study was not part of a clinical trial. Clinical trial registration number: N/A.

Matched MeSH terms: Radiation-Sensitizing Agents/pharmacology*
Fulltext Radiotherapy concurrently with weekly cisplatin, followed by adjuvant chemotherapy, for N2-3 nasopharyngeal cancer: a multicenter trial of the Forum for Nuclear Cooperation in Asia

Ohno T, Thinh DH, Kato S, Devi CR, Tung NT, Thephamongkhol K, et al.

J Radiat Res, 2013 May;54(3):467-73.
PMID: 23192700 DOI: 10.1093/jrr/rrs115

The purpose of this study was to evaluate the efficacy and toxicity of radiotherapy concurrently with weekly cisplatin, followed by adjuvant chemotherapy, for the treatment of N2-3 nasopharyngeal cancer (NPC) in Asian countries, especially regions of South and Southeast Asian countries where NPC is endemic. Between 2005 and 2009, 121 patients with NPC (T1-4 N2-3 M0) were registered from Vietnam, Malaysia, Indonesia, Thailand, The Philippines, China and Bangladesh. Patients were treated with 2D radiotherapy concurrently with weekly cisplatin (30 mg/m (2)), followed by adjuvant chemotherapy, consisting of cisplatin (80 mg/m(2) on Day 1) and fluorouracil (800 mg/m(2) on Days 1-5) for 3 cycles. Of the 121 patients, 56 patients (46%) required interruption of RT. The reasons for interruption of RT were acute non-hematological toxicities such as mucositis, pain and dermatitis in 35 patients, hematological toxicities in 11 patients, machine break-down in 3 patients, poor general condition in 2 patients, and others in 8 patients. Of the patients, 93% completed at least 4 cycles of weekly cisplatin during radiotherapy, and 82% completed at least 2 cycles of adjuvant chemotherapy. With a median follow-up time of 46 months for the surviving 77 patients, the 3-year locoregional control, distant metastasis-free survival and overall survival rates were 89%, 74% and 66%, respectively. No treatment-related deaths occurred. Grade 3-4 toxicities of mucositis, nausea/vomiting and leukopenia were observed in 34%, 4% and 4% of the patients, respectively. In conclusion, further improvement in survival and locoregional control is necessary, although our regimen showed acceptable toxicities.

Matched MeSH terms: Radiation-Sensitizing Agents/administration & dosage
Fulltext A ruthenium polypyridyl intercalator stalls DNA replication forks, radiosensitizes human cancer cells and is enhanced by Chk1 inhibition

Gill MR, Harun SN, Halder S, Boghozian RA, Ramadan K, Ahmad H, et al.

Sci Rep, 2016 08 25;6:31973.
PMID: 27558808 DOI: 10.1038/srep31973

Ruthenium(II) polypyridyl complexes can intercalate DNA with high affinity and prevent cell proliferation; however, the direct impact of ruthenium-based intercalation on cellular DNA replication remains unknown. Here we show the multi-intercalator [Ru(dppz)2(PIP)](2+) (dppz = dipyridophenazine, PIP = 2-(phenyl)imidazo[4,5-f][1,10]phenanthroline) immediately stalls replication fork progression in HeLa human cervical cancer cells. In response to this replication blockade, the DNA damage response (DDR) cell signalling network is activated, with checkpoint kinase 1 (Chk1) activation indicating prolonged replication-associated DNA damage, and cell proliferation is inhibited by G1-S cell-cycle arrest. Co-incubation with a Chk1 inhibitor achieves synergistic apoptosis in cancer cells, with a significant increase in phospho(Ser139) histone H2AX (γ-H2AX) levels and foci indicating increased conversion of stalled replication forks to double-strand breaks (DSBs). Normal human epithelial cells remain unaffected by this concurrent treatment. Furthermore, pre-treatment of HeLa cells with [Ru(dppz)2(PIP)](2+) before external beam ionising radiation results in a supra-additive decrease in cell survival accompanied by increased γ-H2AX expression, indicating the compound functions as a radiosensitizer. Together, these results indicate ruthenium-based intercalation can block replication fork progression and demonstrate how these DNA-binding agents may be combined with DDR inhibitors or ionising radiation to achieve more efficient cancer cell killing.

Matched MeSH terms: Radiation-Sensitizing Agents/metabolism; Radiation-Sensitizing Agents/toxicity; Radiation-Sensitizing Agents/chemistry*