Cancer is a prime healthcare problem that is significantly responsible for universal mortality. Despite distinguished advancements in medical field, chemotherapy is still the mainstay for the treatment of cancers. During chemotherapy, approximately 90% of the administered dose goes to normal tissues, with mere 2-5% precisely reaching the cancerous tissues. Subsequently, the resultant side effects and associated complications lead to dose reduction or even discontinuance of the therapy. Tumor directed therapy therefore, represents a fascinating approach to augment the therapeutic potential of anticancer bioactives as well as overcomes its side effects. The selective overexpression of LHRH receptors on human tumors compared to normal tissues makes them a suitable marker for diagnostics, molecular probes and targeted therapeutics. These understanding enabled the rational to conjugate LHRH with various cytotoxic drugs (doxorubicin, DOX; camptothecin etc.), cytotoxic genes [small interfering RNA (siRNA), micro RNA (miRNA)], as well as therapeutic nanocarriers (nanoparticles, liposomes or dendrimers) to facilitate their tumor specific delivery. LHRH conjugation enhances their delivery via LHRH receptor mediated endocytosis. Numerous cytotoxic analogs of LHRH were developed over the past two decades to target various types of cancers. The potency of LHRH compound were reported to be as high as 5,00-10,00 folds compared to parent molecules. The objective of this review article is to discuss reports on various LHRH analogs with special emphasis on their prospective application in the medical field. The article also focuses on the attributes that must be taken into account while designing a LHRH therapeutics with special account to the biochemistry and applications of these conjugates. The record on various cytotoxic analogs of LHRH are also discussed. It is anticipated that the knowledge of therapeutic and toxicological aspects of LHRH compounds will facilitate the development of a more systematic approach to the targeted delivery of cytotoxic agents using peptides.
Synthetic glucocorticoid (dexamethasone; DEX) treatment during the neonatal stage is known to affect reproductive activity. However, it is still unknown whether neonatal stress activates gonadotropin-inhibitory hormone (GnIH) synthesizing cells in the dorsomedial hypothalamus (DMH), which could have pronounced suppressive action on gonadotropin-releasing hormone (GnRH) neurons, leading to delayed pubertal onset. This study was designed to determine the effect of neonatal DEX (1.0mg/kg) exposure on reproductive maturation. Therefore, GnRH, GnIH and GnIH receptors, G-protein coupled receptors (GPR) 147 and GPR74 mRNA levels were measured using quantitative real-time PCR in female mice at postnatal (P) days 21, 30 and in estrus stage mice, aged between P45-50. DEX-treated females of P45-50 had delayed vaginal opening, and irregular estrus cycles and lower GnRH expression in the preoptic area (POA) when compared with age-matched controls. The expression levels of GPR147 and GPR74 mRNA in the POA increased significantly in DEX-treated female mice of P21 and P45-50 compared to controls. In addition, GPR147 and GPR74 mRNA expression was observed in laser captured single GnRH neurons in the POA. Although there was no difference in GnIH mRNA expression in the DMH, immunostained GnIH cell numbers in the DMH increased in DEX-treated females of P45-50 compared to controls. Taken together, the results show that the delayed pubertal onset could be due to the inhibition of GnRH gene expression after neonatal DEX treatment, which may be accounted for in part by the inhibitory signals from the up-regulated GnIH-GnIH receptor pathway to the POA.
Recent discoveries of somatic mutations permit the recognition of subtypes of aldosterone-producing adenomas with distinct clinical presentations and pathological features. Here we describe three women with hyperaldosteronism, two who presented in pregnancy and one who presented after menopause. Their aldosterone-producing adenomas harbored activating mutations of CTNNB1, encoding β-catenin in the Wnt cell-differentiation pathway, and expressed LHCGR and GNRHR, encoding gonadal receptors, at levels that were more than 100 times as high as the levels in other aldosterone-producing adenomas. The mutations stimulate Wnt activation and cause adrenocortical cells to de-differentiate toward their common adrenal-gonadal precursor cell type. (Funded by grants from the National Institute for Health Research Cambridge Biomedical Research Centre and others.).