Emerging Roles of Carotenoids in the Survival and Adaptations of Microbes

Genetic Underpinnings of Carotenogenesis and Light-Induced Transcriptome Remodeling in the Opportunistic Pathogen Mycobacterium kansasii

Mycobacterium kansasii (Mk) causes opportunistic pulmonary infections with tuberculosis-like features. The bacterium is well known for its photochromogenicity, i.e., the production of carotenoid pigments in response to light. The genetics defining the photochromogenic phenotype of Mk has not been investigated and defined pigmentation mutants to facilitate studies on the role of carotenes in the bacterium's biology are not available thus far. In this study, we set out to identify genetic determinants involved in Mk photochromogenicity. We screened a library of ~150,000 transposon mutants for colonies with pigmentation abnormalities. The screen rendered a collection of ~200 mutants. Each of these mutants could be assigned to one of four distinct phenotypic groups. The insertion sites in the mutant collection clustered in three chromosomal regions. A combination of phenotypic analysis, sequence bioinformatics, and gene expression studies linked these regions to carotene biosynthesis, carotene degradation, and monounsaturated fatty acid biosynthesis. Furthermore, introduction of the identified carotenoid biosynthetic gene cluster into non-pigmented Mycobacterium smegmatis endowed the bacterium with photochromogenicity. The studies also led to identification of MarR-type and TetR/AcrR-type regulators controlling photochromogenicity and carotenoid breakdown, respectively. Lastly, the work presented also provides a first insight into the Mk transcriptome changes in response to light.

Impact of dietary vitamin A deficiency on body physiology and liver metabolism of Wistar rats

Background: Studies suggest that vitamin A deficiency (VAD) can cause night blindness or xerophthalmia, hepatic and metabolic changes in the blood. Aim: Therefore, this work aimed to stablish a model of hypovitaminosis A in rats and to evaluate the effects of vitamin A deficiency on metabolic and oxidative parameters in the liver of rats. Methods: Male (n = 19), Wistar, rats (21-day-old) weighing 50g, divided into two experimental groups: Control Group (C), received AIN 93G diet and Vitamin A Deficiency Group (VAD), received AIN 93G vitamin A-free diet for 45 days. In this work, the parameters analyzed were: body mass, food and water intake, biochemical aspects in the blood, lipids and glycogen content, lipid peroxidation, carbonyl proteins and catalase activity in the liver. Results: In the VAD group, final body mass (9%), liver mass (28%), glycemia (14%), Total -cholesterol (17%), HDL -cholesterol (31%) and VLDL -cholesterol (30%) showed reduced (p < 0.05). The liver lipid (64%) and glyceride-fatty acid (74%) contents were higher in the VAD group. The carbonyl proteins in liver were increased by 171% (p < 0.05). Conclusion: In summary, these results suggest that the absence of vitamin A from the diet was effective in inducing characteristics of hypovitaminosis A in rats. This way, can be used for studies related to glucose and lipid metabolism.

Therapeutic Role of Carotenoids in Blood Cancer: Mechanistic Insights and Therapeutic Potential

Blood cancers are characterized by pathological disorders causing uncontrolled hematological cell division. Various strategies were previously explored for the treatment of blood cancers, including chemotherapy, Car-T therapy, targeting chimeric antigen receptors, and platelets therapy. However, all these therapies pose serious challenges that limit their use in blood cancer therapy, such as poor metabolism. Furthermore, the solubility and stability of anticancer drugs limit efficacy and bio-distribution and cause toxicity. The isolation and purification of natural killer cells during Car-T cell therapy is a major challenge. To cope with these challenges, treatment strategies from phyto-medicine scaffolds have been evaluated for blood cancer treatments. Carotenoids represent a versatile class of phytochemical that offer therapeutic efficacy in the treatment of cancer, and specifically blood cancer. Carotenoids, through various signaling pathways and mechanisms, such as the activation of AMPK, expression of autophagy biochemical markers (p62/LC3-II), activation of Keap1-Nrf2/EpRE/ARE signaaling pathway, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), increased level of reactive oxygen species, cleaved poly (ADP-ribose) polymerase (c-PARP), c-caspase-3, -7, decreased level of Bcl-xL, cycle arrest at the G0/G1 phase, and decreasing STAT3 expression results in apoptosis induction and inhibition of cancer cell proliferation. This review article focuses the therapeutic potential of carotenoids in blood cancers, addressing various mechanisms and signaling pathways that mediate their therapeutic efficacy.

Dietary Carotenoids in Head and Neck Cancer-Molecular and Clinical Implications

Head and neck cancer (HNC) is one of the most common cancers in the world according to GLOBCAN. In 2018, it was reported that HNC accounts for approximately 3% of all human cancers (51,540 new cases) and is the cause of nearly 1.5% of all cancer deaths (10,030 deaths). Despite great advances in treatment, HNC is indicated as a leading cause of death worldwide. In addition to having a positive impact on general health, a diet rich in carotenoids can regulate stages in the course of carcinogenesis; indeed, strong epidemiological associations exist between dietary carotenoids and HNS, and it is presumed that diets with carotenoids can even reduce cancer risk. They have also been proposed as potential chemotherapeutic agents and substances used in chemoprevention of HNC. The present review discusses the links between dietary carotenoids and HNC. It examines the prospective anticancer effect of dietary carotenoids against intracellular cell signalling and mechanisms, oxidative stress regulation, as well as their impact on apoptosis, cell cycle progression, cell proliferation, angiogenesis, metastasis, and chemoprevention; it also provides an overview of the limited preclinical and clinical research published in this arena. Recent epidemiological, key opinion-forming systematic reviews, cross-sectional, longitudinal, prospective, and interventional studies based on in vitro and animal models of HNC also indicate that high carotenoid content obtained from daily supplementation has positive effects on the initiation, promotion, and progression of HNC. This article presents these results according to their increasing clinical credibility.

Carotenoids and Carcinogenesis: Exploring the Antioxidant and Cell Signaling Roles of Carotenoids in the Prevention of Cancer

Carotenoids are lipid soluble pigments found in various fruits and vegetables and are naturally produced in photoautotrophic plants. Various studies have investigated the properties of carotenoids to determine how they are able to mitigate numerous diseases, including cancer. Carotenoids present in human serum, including β-carotene, α-carotene, lycopene, β-cryptoxanthin, zeaxanthin, and lutein have demonstrated the ability to act as anticarcinogenic agents. Prevention of disease is often described to be more effective than treatment; as cancer impacts millions of lives globally, the role of carotenoids in the prevention of oncogenesis for numerous types of cancers have been extensively researched. This review provides an in-depth analysis of the structure and properties of carotenoids, as well as the identified and potential mechanisms by which carotenoids can act as a chemopreventative agent.

Mediterranean diet and breast cancer risk: a narrative review

Breast cancer is the second most frequent type of cancer worldwide and the most commonly occurring malignancy in women, and its incidence is increasing in most developed and developing countries. There is growing evidence that lifestyle factors, in particular diet may be associated with higher breast cancer risk. Some evidence exists regarding the benefit of Mediterranean diet on reduced risk of breast cancer in premenopausal and postmenopausal women. The protective effect of the Mediterranean diet against the risk of breast cancer, is primarily due to principal foods of this nutritional pattern. The principal components of the Mediterranean diet, such as fruits and vegetables, olive oil, fish and red wine have important antioxidants properties due to their high content of substances like polyphenols, flavonoids, carotenoids and fibers, along with a favorable fatty acid profile, that in turn could reduce the risk of breast cancer. Considering the severity of breast cancer and the increasing incidence in the world, there is an increasing interest in promoting prevention strategies in order to reduce the incidence. The aim of this paper is to provide a general overview of the current evidence on the relationship between breast cancer and Mediterranean diet, in premenopausal and postmenopausal women, and to emphasize the potential role of Mediterranean Diet as an effective tool in primary prevention. The possible molecular mechanisms underlying this association will be also pointed out.