Genotoxicity and mutagenicity induced by acute crack cocaine exposure in mice

Cocaine use and head and neck cancer risk: A pooled analysis in the International Head and Neck Cancer Epidemiology Consortium

BACKGROUND

Cocaine is an illegal recreational drug used worldwide, yet little is known about whether cocaine inhalation (smoking/snorting) increases the risk of head and neck cancer (HNC).

METHODS

The analyses were conducted by pooling data from three case-control studies with 1639 cases and 2506 controls from the International Head and Neck Cancer Epidemiology Consortium. Epidemiologic data, including cocaine use histories, were obtained in face-to-face interviews. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated using hierarchical logistic regression models.

RESULTS

Controlling for cumulative tobacco and alcohol use, we observed a weak positive association between cocaine use and HNC (ORever vs. never  = 1.35, 95% CI: 0.96, 1.90). In stratified analysis, while we did not detect associations among never tobacco or alcohol users due to the limited sample size, the association with cocaine use was observed among tobacco users and alcohol drinkers. ORs for ever and high cumulative use (>18 times) versus never use were 1.40 (95% CI: 0.98, 2.00) and 1.66 (95% CI: 1.03, 2.69) among tobacco users, and 1.34 (95% CI: 0.93, 1.92) and 1.59 (95% CI: 1.00, 2.51) among alcohol drinkers, respectively.

CONCLUSION

In this pooled analysis, we observed a weak positive association between cocaine inhalation and HNC risk. Our findings provide preliminary evidence of the potential carcinogenic effect of cocaine on HNC. Because of study limitations, including limited number of cocaine users, confounding, and heterogeneity across studies, future investigations will require larger studies with more detailed information on cocaine use history.

Environmental exposures associated with elevated risk for autism spectrum disorder may augment the burden of deleterious de novo mutations among probands

Although the full aetiology of autism spectrum disorder (ASD) is unknown, familial and twin studies demonstrate high heritability of 60-90%, indicating a predominant role of genetics in the development of the disorder. The genetic architecture of ASD consists of a complex array of rare and common variants of all classes of genetic variation usually acting additively to augment individual risk. The relative contribution of heredity in ASD persists despite selective pressures against the classic autistic phenotype; a phenomenon thought to be explained, in part, by the incidence of spontaneous (or de novo) mutations. Notably, environmental exposures attributed as salient risk factors for ASD may play a causal role in the emergence of deleterious de novo variations, with several ASD-associated agents having significant mutagenic potential. To explore this hypothesis, this review article assesses published epidemiological data with evidence derived from assays of mutagenicity, both in vivo and in vitro, to determine the likely role such agents may play in augmenting the genetic liability in ASD. Broadly, these exposures were observed to elicit genomic alterations through one or a combination of: (1) direct interaction with genetic material; (2) impaired DNA repair; or (3) oxidative DNA damage. However, the direct contribution of these factors to the ASD phenotype cannot be determined without further analysis. The development of comprehensive prospective birth cohorts in combination with genome sequencing is essential to forming a causal, mechanistic account of de novo mutations in ASD that links exposure, genotypic alterations, and phenotypic consequences.

Sub-lethal combined effects of illicit drug and decreased pH on marine mussels: A short-time exposure to crack cocaine in CO2 enrichment scenarios

The increasing CO₂-concentrations in the atmosphere promote ocean acidification. Seawater chemistry changes interact with contaminants, such as illicit drugs in the coastal zones. This work evaluates impacts of pH decrease and crack-cocaine exposure on the commercial mussel Perna perna through biomarker responses (lysosomal membrane stability, lipid peroxidation, and DNA strand breaks). The organisms were exposed to different crack-cocaine concentrations (0.5, 5.0, and 50 μg L^-1) combined with different pH values (8.3, 8.0, 7.5, 7.0, 6.5, and 6.0) for 96 h. Crack-cocaine in the different acidification scenarios triggered cyto-genotoxicity, which affected the overall health of mussels exposed to cocaine environmentally relevant concentration. This study produced the first data on biomarker responses associated with CO₂-induced acidification and illicit drugs (crack-cocaine) in marine organisms.

Inhibition of Toll Like Signaling Pathway Is Associated With Genomic Instability in Rat Liver Exposed to Crack Cocaine

BACKGROUND/AIM

The aim of the present study was to investigate the biological effects of subacute crack cocaine exposure in rat liver.

MATERIAL AND METHODS

A total of 32 rats were distributed into four groups (n=8): Experimental group 1 (G1) and Experimental group 2 (G2): rats received 18 mg/kg of body weight (b.w) of crack cocaine for 5 days, once a day, group G2 remained 72 h without exposure after the experimental period (5 days)(abstinence); Experimental group 3 (G3): rats received 36 mg/kg of body weight (b.w) of crack cocaine for 5 days, once a day; Control Group (CTRL): rats received only the vehicle (DMSO) administered by the intraperitoneal (i.p) route for 5 days, once a day.

RESULTS

All groups exposed to crack cocaine had an increase in the number of micronucleated hepatocytes and binucleated cells only in the highest tested dose (36 mg/kg). Karyolysis had an increase in the 18 mg/kg dose, in the abstinence group (G2), and 36 mg/kg group (G3); whereas pyknotic nuclei had an increase in the G2 group. The group exposed to 18 mg/kg of crack cocaine also showed high 8 OHdG expression. The p-NF-κB p65 protein decreased in the groups exposed to crack cocaine at doses of 18 and 36 mg/kg, as well as in the abstinence group. MyD88 was also found decreased in the group exposed to crack cocaine at 18 mg/kg.

CONCLUSION

Crack cocaine inhibited toll like signaling pathway whilst being associated with genomic instability in rat liver cells.

Genotoxicity, oxidative stress, and inflammatory response induced by crack-cocaine: relevance to carcinogenesis

Crack-cocaine is a cocaine by-product widely consumed by general population in developing countries. The drug is low cost and is associated with more intense effects when compared to other illicit drugs. Genotoxicity, oxidative stress, and inflammatory response are considered crucial events in carcinogenesis, since they actively participate in the multistep process. The purpose of this paper was to provide a mini review regarding the relationship between carcinogenesis and genotoxicity, oxidative stress, and inflammation induced by crack-cocaine. The present study was conducted on search of the scientific literature from the published studies available in PubMed, MEDLINE, Scopus, and Google Scholar for all kind of articles (all publications to November 2020) using the following key words: crack-cocaine, DNA damage, genotoxicity, cellular death, cytotoxicity, mutation, oxidative stress, inflammation, and mutagenicity. The results showed that published papers available were almost all in vivo test system being conducted in humans or rodents. Crack-cocaine was able to induce genotoxicity and oxidative stress in mammalian cells. However, the role of inflammatory response after exposure to crack-cocaine was not conclusive so far. In summary, this study is consistent with the notion that crack-cocaine is a chemical carcinogen as a result of genotoxicity and oxidative stress induced in mammalian and non-mammalian cells.

Argyrophilic nucleolar organizer regions in oral mucosa cells of crack and cocaine users: a cross-sectional study

The objective of this study was to analyze and compare the presence of argyrophilic nucleolar organizer regions (AgNORs) in exfoliated cells obtained from the buccal mucosa among crack and cocaine users and non-users by the AgNOR staining technique. Seventy-three males ≥ 18 years were categorized into two groups: 38 crack and/or cocaine users and 35 non-user volunteers. They were interviewed and responded a questionnaire regarding general health and drug addiction. Exfoliative cytology specimens were collected from the clinically intact buccal mucosa, and cytological preparations were fixed and stained by AgNOR technique. The mean number of AgNORs (p = 0.02) and the percentage of epithelial cells with more than 3 (p = 0.01) and 4 (p = 0.04) AgNORs/nucleus were significantly higher in the non-user group. In conclusion, the frequency and diversity of substances present in the drugs-cocaine, crack, and alcohol-consumed by the volunteers of this study may have influenced the number of AgNORs and the response to damage and consequent effect on protein synthesis.

Exposure to crack cocaine causes adverse effects on marine mussels Perna perna

Our study aimed to evaluate crack cocaine effects in different life stages of the marine mussel Perna perna. For this purpose, fertilization rate, embryo-larval development, lysosomal membrane stability and DNA strand breaks were assessed. Effect concentrations in gametes and in larval development were found after 1h (IC₅₀=23.53mg·L^-1) and 48h (IC₅₀=16.31mg·L^-1), respectively. The highest tested concentration showing no acute toxicity (NOEC) was 10mg·L^-1, while the lowest observed effect concentration (LOEC) was 20mg·L^-1. NOEC concerning embryo-larval development was 0.625mg·L^-1, while the LOEC was 1.25mg·L^-1. Cyto-genotoxic effects were evidenced in mussels exposed to crack cocaine concentrations ranging from 5 to 500μg·L^-1. Our results report the first data on effects of an illicit drug to marine organisms and should encourage further ecotoxicological studies of these contaminants of emerging concern in coastal ecosystems.