Hippokratis Kiaris

Chemokine receptors play crucial roles in tumor onset and progression, but the high redundancy between ligands and their receptors limits the possibilities to leverage them therapeutically for cancer management. To overcome this limitation, we developed chimeric chemokine peptides in which CCL2 and CCL8 were conjugated to diphtheria toxin (DT) and evaluated their antitumor activity. Cytotoxic peptides DTCCL2 and DTCCL8 were produced as recombinant proteins, and their anticancer activity was tested in vitro in cultured cells and in vivo in tumor-bearing mice. The uptake of the cytotoxic analogs was evaluated before and after therapy in tumor explants ex vivo. Both analogs were cytotoxic to breast cancer cells in vitro and produced significant anticancer activity in vivo in mice bearing human breast cancer lines and hormone-negative breast cancer patient-derived xenografts (PDXs). In vitro, the peptide conjugates exhibited overlapping uptake profiles, with about 80% of the breast cancer cells being positive for both peptides and about 15%-20% of the cells being negative for either or both of the cytotoxic peptides. In tumor explants cultured ex vivo, simultaneous positivity for DTCCL2 and DTCCL8 increased to >95%, with less than 5% of the cells showing neither DTCCL8 nor DTCCL2 uptake. Treatment of breast cancer-bearing mice with DTCCL8 or DTCCL2 significantly inhibited tumor growth and prolonged survival in the PDX model. These results support the feasibility of cytotoxic peptide conjugates for breast cancer management and show that receptor expression profiles in vitro do not accurately forecast tumoral positivity.

An optimal glucocorticoid stress response is essential because it allows animals to adjust their phenotype to constantly changing environments. Considerable progress has been made regarding our understanding of how various cellular mechanisms of glucocorticoid action modulate animals' stress response phenotype. However, a potentially overlooked mediator of glucocorticoid production and individual's stress response phenotype is the endoplasmic reticulum (ER) and its unfolded protein response (UPR), given that all steroid hormones are synthesised within the mitochondria and the ER. We hypothesise that UPR regulates glucocorticoid synthesis, and ER stress induction would inhibit glucocorticoid production in the adrenal cortex. We conducted in vivo and in vitro studies using outbred deer mice Peromyscus maniculatus and Y‐1 adrenal cell lines respectively to investigate the effects of ER stress and UPR on adrenocorticotropic hormone induced glucocorticoid production. Specifically, we tested if induction and alleviation of ER stress using tunicamycin and tauroursodeoxycholic acid, respectively, would affect corticosterone production in deer mice and Y‐1 cells and the protein expression of a steroidogenic enzyme in Y‐1 cells. We showed that ER stress and UPR modulate glucocorticoid production at both the cell and whole‐organism levels, but this is achieved independent of alteration in protein level of 21‐Hydroxylase.

Kinship relationships between parents affect offspring fitness. Beyond its effects in heterozygosity or its impact in deleterious alleles that can be reduced to homozygosity and decrease the individuals' fitness, the consequences of parental relatedness in the offspring remain understudied. By leveraging the availability of detailed pedigrees of captive Peromyscus, we explored how parental relatedness impacts the methylome and the epigenetic age estimation of the offspring. Global CpG methylation analysis showed that parental relatedness positively impacts lifespan expectancy and reduces epigenetic ageing, contributing about 13% of variancein epigenetic age estimation. Global hypermethylation due to relatedness was considerably higher than hypomethylation, was more pronounced in the male offspring, and mainly affected chromosomal loci associated with development. A relatedness-associated methylation signature was described that predicts parental relatedness with high accuracy, providing the proof of concept that kinship relationships can be inferred by epigenetic analyses. These findings identify parental relatedness as a modifier of epigenetic ageing and global methylation, suggesting that kinship relations should be considered when epigenetic, and potentially transcriptomic data are interpreted in the context of ageing and of other pathophysiological processes.

Increased parental relatedness occurs in small wild populations and in closed colonies in captivity and reduces offspring fitness. A closed colony of Peromyscus maniculatus is maintained as genetically diverse stock at the Peromyscus Genetic Stock Center since 1963. Breeding records are available for all the years of breeding in captivity, which allows evaluation of the breeding performance since the inception of the stock. Kinship calculations showed that increased parental relatedness results in offspring loss, which is consistent with the operation of inbreeding depression and is common in small populations, both wild and captive. Nonetheless, an adaptive response was recorded that mitigated the adverse consequences of inbreeding and contributed to the long‐term stability of the colony: When parental relatedness increased, more offspring were produced, resulting in the overall number of viable offspring being unaffected. The underlying mechanism involved adjustments in the interval for mating between related parents, causing the production of more litters. These adaptive changes indicate that the harmful consequences of inbreeding may be partially relieved by mechanisms involving changes in the animals' reproductive strategy. The availability of the breeding records of P. maniculatus enables the performance of additional studies asking different questions regarding the breeding dynamics of a closed colony under regulated conditions.

Deregulation of chemokine CCL8 expression is common in various malignancies and other pathologies and plays a causative role in disease progression. However, despite CCL8's acknowledged role in pathology, inhibition of its activity does not represent a strategy of choice for cancer management. This is because its function overlaps with that of the other structurally related chemokines, and its activity is mediated by more than one receptor. To overcome this limitation, we hypothesized that ablation of CCL8 cellular targets, as opposed to disruption of CCL8 activity, may be more advantageous. Therefore, we developed DTCCL8, a chimeric cytotoxic peptide that delivers diphtheria toxin into cells expressing CCL8 receptors which are overexpressed in both the cells of tumor microenvironment and the cancer cells. The specificity of this peptide was confirmed in vitro by testing the cytotoxic activity of breast cancer cells overexpressing CCR5, a major CCL8 receptor, and by a neutralizing anti‐CCL8 antibody we developed. In vivo , DTCCL8 transiently reduced lymphocytes in blood, and its anticancer activity was confirmed in mouse breast cancers triggered by the polyoma middle T oncogene. These findings suggest that DTCCL8 can be used as a prototype for the development of a novel class of breast cancer therapeutics, targeting chemokine targets instead of inhibiting their activity. These cytotoxic peptides may also be useful for managing cancers and other immune system‐associated pathologies.

Photoperiod is the major regulator of circannual patterns in mammals, but at animal facilities, despite the controlled conditions, some rodents still exhibit seasonality in their breeding. By evaluating more than 97,000 breeding records of closed Peromyscus colonies, we explored if seasonal breeding patterns exist in animals maintained for several decades at controlled environments. Seasonal preferences for offspring production were recorded that depended on maternal birth month. Birth in March and September, especially of mothers, showed best fit in 12-knots generalized additive models, implying that the memory of birth month is more intensively carried during the Spring and Autumn equinoxes. The memory of birth month was associated with circannual CpG methylation at birth and revealed that most intense differential methylation, primarily demethylation, occurs in animals that were born in September. Comparison of breeding performance in the periods between the equinoxes showed preference for summer littering by the winter-born animals, especially in the polygamous P. maniculatus bairdii and P. leucopus stocks, and at least in the former species, this was associated with longer estrus cycles. Genes associated with differentially methylated CpGs in winter and summer periods in polygamous species pointed to regulation of gonadotropin hormone releasing hormone secretion. Birth at individually ventilated cages disrupted methylation profiles. The cyclicity of breeding and methylation patterns suggest that signals other than the photoperiod regulate circannual patterns in deer mice, that reset in the equinox especially in autumn, and that the females are more sensitive to these signals than males.

"RETRACTION: Improvement of chemotherapeutic drug efficacy by endoplasmic reticulum stress" published on 01 Nov 2024 by Bioscientifica Ltd.