-
Communications Biology Aug 2020Transgenic rodent (TGR) models use bacterial reporter genes to quantify in vivo mutagenesis. Pairing TGR assays with next-generation sequencing (NGS) enables...
Transgenic rodent (TGR) models use bacterial reporter genes to quantify in vivo mutagenesis. Pairing TGR assays with next-generation sequencing (NGS) enables comprehensive mutation pattern analysis to inform mutational mechanisms. We used this approach to identify 2751 independent lacZ mutations in the bone marrow of MutaMouse animals exposed to four chemical mutagens: benzo[a]pyrene, N-ethyl-N-nitrosourea, procarbazine, and triethylenemelamine. We also collected published data for 706 lacZ mutations from eight additional environmental mutagens. We report that lacZ gene sequencing generates chemical-specific mutation signatures observed in human cancers with established environmental causes. For example, the mutation signature of benzo[a]pyrene, a carcinogen present in tobacco smoke, matched the signature associated with tobacco-induced lung cancers. Our results suggest that the analysis of chemically induced mutations in the lacZ gene shortly after exposure provides an effective approach to characterize human-relevant mechanisms of carcinogenesis and propose novel environmental causes of mutation signatures observed in human cancers.
Topics: Animals; Genes, Reporter; Genome, Human; High-Throughput Nucleotide Sequencing; Humans; Male; Mice, Transgenic; Mutation; Mutation Rate; Neoplasms; Transgenes; beta-Galactosidase
PubMed: 32796912
DOI: 10.1038/s42003-020-01174-y -
Archives of Toxicology Mar 2021The Organisation for Economic Co-Operation and Development Test Guideline 488 (TG 488) uses transgenic rodent models to generate in vivo mutagenesis data for regulatory...
The Organisation for Economic Co-Operation and Development Test Guideline 488 (TG 488) uses transgenic rodent models to generate in vivo mutagenesis data for regulatory submission. The recommended design in TG 488, 28 consecutive daily exposures with tissue sampling three days later (28 + 3d), is optimized for rapidly proliferating tissues such as bone marrow (BM). A sampling time of 28 days (28 + 28d) is considered more appropriate for slowly proliferating tissues (e.g., liver) and male germ cells. We evaluated the impact of the sampling time on mutant frequencies (MF) in the BM of MutaMouse males exposed for 28 days to benzo[a]pyrene (BaP), procarbazine (PRC), isopropyl methanesulfonate (iPMS), or triethylenemelamine (TEM) in dose-response studies. BM samples were collected + 3d, + 28d, + 42d or + 70d post exposure and MF quantified using the lacZ assay. All chemicals significantly increased MF with maximum fold increases at 28 + 3d of 162.9, 6.6, 4.7 and 2.8 for BaP, PRC, iPMS and TEM, respectively. MF were relatively stable over the time period investigated, although they were significantly increased only at 28 + 3d and 28 + 28d for TEM. Benchmark dose (BMD) modelling generated overlapping BMD confidence intervals among the four sampling times for each chemical. These results demonstrate that the sampling time does not affect the detection of mutations for strong mutagens. However, for mutagens that produce small increases in MF, sampling times greater than 28 days may produce false-negative results. Thus, the 28 + 28d protocol represents a unifying protocol for simultaneously assessing mutations in rapidly and slowly proliferating somatic tissues and male germ cells.
Topics: Animals; Dose-Response Relationship, Drug; Germ Cells; Male; Mice; Mice, Transgenic; Mutagenesis; Mutagenicity Tests; Mutagens; Mutation; Time Factors
PubMed: 33506374
DOI: 10.1007/s00204-021-02977-6 -
Lab on a Chip Aug 2015The dose-dependent bioactivity of small molecules on cells is a crucial factor in drug discovery and personalized medicine. Although small-molecule microarrays are a...
The dose-dependent bioactivity of small molecules on cells is a crucial factor in drug discovery and personalized medicine. Although small-molecule microarrays are a promising platform for miniaturized screening, it has been a challenge to use them to obtain quantitative dose-response curves in vitro, especially for lipophilic compounds. Here we establish a small-molecule microarray assay capable of controlling the dosage of small lipophilic molecules delivered to cells by varying the sub-cellular volumes of surface supported lipid micro- and nanostructure arrays fabricated with nanointaglio. Features with sub-cellular lateral dimensions were found necessary to obtain normal cell adhesion with HeLa cells. The volumes of the lipophilic drug-containing nanostructures were determined using a fluorescence microscope calibrated by atomic-force microscopy. We used the surface supported lipid volume information to obtain EC-50 values for the response of HeLa cells to three FDA-approved lipophilic anticancer drugs, docetaxel, imiquimod and triethylenemelamine, which were found to be significantly different from neat lipid controls. No significant toxicity was observed on the control cells surrounding the drug/lipid patterns, indicating lack of interference or leakage from the arrays. Comparison of the microarray data to dose-response curves for the same drugs delivered liposomally from solution revealed quantitative differences in the efficacy values, which we explain in terms of cell-adhesion playing a more important role in the surface-based assay. The assay should be scalable to a density of at least 10,000 dose response curves on the area of a standard microtiter plate.
Topics: Aminoquinolines; Antineoplastic Agents; Cell Adhesion; Cell Survival; Docetaxel; Drug Discovery; HeLa Cells; Humans; Imiquimod; Liposomes; Microarray Analysis; Microscopy, Atomic Force; Microscopy, Fluorescence; Nanostructures; Precision Medicine; Taxoids; Triethylenemelamine
PubMed: 26167949
DOI: 10.1039/c5lc00478k -
Dermatology Online Journal Nov 2018Cryotherapy is a commonly discussed method for treatment of basal cell carcinoma skin cancer. Some uncertainty remains about its efficacy relative to other modalities. (Comparative Study)
Comparative Study
BACKGROUND
Cryotherapy is a commonly discussed method for treatment of basal cell carcinoma skin cancer. Some uncertainty remains about its efficacy relative to other modalities.
OBJECTIVE
To determine the efficacy and adverse events profile of cryotherapy for the treatment of basal cell carcinoma compared to other therapeutic options or non-intervention.
METHODS
We systematically searched PubMed, OVID, Cochrane Library, EMBASE, CINHAL, and CANCERLIT databases for the following terms: "cryotherapy", AND "basal cell carcinoma", OR "cryosurgery" OR "cryoablation" up to April 2018. Two independent reviewers screened the results and extracted the data. Study endpoints included basal cell carcinoma recurrence, cosmetic outcome, and healing time. Study quality was assessed using the Jadad scale.
RESULTS
Six clinical studies met our inclusion criteria. The efficacy and safety of cryotherapy alone or with curettage in the treatment of primary superficial and nodular basal cell carcinoma was comparable to photodynamic therapy and surgery, respectively. Cryotherapy was inferior to radiation in terms of recurrence rate. Most patients had better cosmetic outcomes with photodynamic therapy and surgery compared to cryotherapy alone, and cryotherapy with curettage.
CONCLUSION
Current available data suggests equivalent efficacy of cryotherapy alone compared to photodynamic therapy or surgery, but inferior to radiotherapy. More studies are necessary to draw definitive conclusions.
Topics: Carcinoma, Basal Cell; Cryosurgery; Dermatologic Surgical Procedures; Humans; Neoplasm Recurrence, Local; Photochemotherapy; Skin Neoplasms; Triethylenemelamine; Wound Healing
PubMed: 30695972
DOI: No ID Found -
Journal of Clinical Oncology : Official... Oct 2014Hereditary retinoblastoma (Rb) survivors have increased risk of subsequent malignant neoplasms (SMNs). Previous studies reported elevated radiotherapy (RT) -related SMN...
PURPOSE
Hereditary retinoblastoma (Rb) survivors have increased risk of subsequent malignant neoplasms (SMNs). Previous studies reported elevated radiotherapy (RT) -related SMN risks, but less is known about chemotherapy-related risks.
PATIENTS AND METHODS
In a long-term follow-up study of 906 5-year hereditary Rb survivors diagnosed from 1914 to 1996 and observed through 2009, treatment-related SMN risks were quantified using cumulative incidence analyses and multivariable Cox proportional hazards regression models with age as the underlying time scale.
RESULTS
Nearly 90% of Rb survivors were treated with RT, and almost 40% received alkylating agent (AA) -containing chemotherapy (predominantly triethylenemelamine). Median follow-up time to first SMN diagnosis was 26.3 years. Overall SMN risk was not significantly elevated among survivors receiving AA plus RT versus RT without chemotherapy (hazard ratio [HR], 1.27; 95% CI, 0.99 to 1.63). AA-related risks were significantly increased for subsequent bone tumors (HR, 1.60; 95% CI, 1.03 to 2.49) and leiomyosarcoma (HR, 2.67; 95% CI, 1.22 to 5.85) but not for melanoma (HR, 0.74; 95% CI, 0.36 to 1.55) or epithelial tumors (HR, 0.89; 95% CI, 0.48 to 1.64). Leiomyosarcoma risk was significantly increased for survivors who received AAs at age < 1 (HR, 5.17; 95% CI, 1.76 to 15.17) but not for those receiving AAs at age ≥ 1 year (HR, 1.75; 95% CI, 0.68 to 4.51). Development of leiomyosarcoma was significantly more common after AA plus RT versus RT (5.8% v 1.6% at age 40 years; P = .01).
CONCLUSION
This comprehensive quantification of SMN risk after chemotherapy and RT among hereditary Rb survivors also demonstrates an AA-related contribution to risk. Although triethylenemelamine is no longer prescribed, our findings warrant further follow-up to investigate potential SMN risks associated with current chemotherapies used for Rb.
Topics: Antineoplastic Agents, Alkylating; Child, Preschool; Female; Follow-Up Studies; Humans; Infant; Longitudinal Studies; Male; Neoplasms, Second Primary; Retinal Neoplasms; Retinoblastoma; Retrospective Studies; Risk; Survival Rate; Survivors; Triethylenemelamine; United States
PubMed: 25185089
DOI: 10.1200/JCO.2013.54.7844