Somatostatin analog lanreotide in the treatment of castration-resistant prostate cancer (CRPC)

The State-of-the-Art Mechanisms and Antitumor Effects of Somatostatin in Colorectal Cancer: A Review

Somatostatin, a somatotropin release inhibiting factor (SST, SRIF), is a widely distributed multifunctional cyclic peptide and acts through a transmembrane G protein-coupled receptor (SST1-SST5). Over the past decades, research has begun to reveal the molecular mechanisms underlying the anticancer activity of this hormonal peptide. Among gastrointestinal tract (GIT) tumors, direct and indirect antitumor effects of SST have been documented best in gastroenteropancreatic neuroendocrine tumors (GEP-NETs) and less well in non-endocrine cancers, including sporadic colorectal cancer (CRC). In the latter, the signaling pathways involved in the antitumor function of SST are primarily MAPK/ERK/AKT and Wnt/β-catenin. Direct (involving the MAPK pathway) and indirect (VEGF production) antiangiogenic effects of SST in CRC have also been described. The anti-inflammatory role of SST in CRC is emphasized, but detailed molecular mechanisms are still being explored. The role of SST in tumor genome/tumor microenvironment (TME)/host's gut microbiome interactions is only partially known. The results of SST analogues (SSAs)' treatment of sporadic CRC in monotherapy in vivo are not spectacular. The current review aims to present the state-of-the-art mechanisms and antitumor activity of endogenous SST and its synthetic analogues in CRC, with particular emphasis on sporadic CRC.

Effects of N-Acetylcysteine on the Proliferation, Hormone Secretion Level, and Gene Expression Profiles of Goat Ovarian Granulosa Cells

The purpose of this paper was to investigate the effects of N-acetylcysteine (NAC) on the proliferation, hormone secretion, and mRNA expression profiles of ovarian granulosa cells (GCs) in vitro. A total of 12 ovaries from 6 follicular-stage goats were collected for granulosa cell extraction. The optimum concentration of NAC addition was determined to be 200 μM via the Cell Counting Kit 8 (CCK-8) method. Next, GCs were cultured in a medium supplemented with 200 μM NAC (200 μM NAC group) and 0 μ M NAC (control group) for 48 h. The effects of 200 μM NAC on the proliferation of granulosa cells and hormones were studied by 5-ethynyl-2'-deoxyuridine (EdU) assay and enzyme-linked immunosorbent assay (ELISA). mRNA expression was analyzed by transcriptome sequencing. The results indicate that 200 μM NAC significantly increased cell viability and the proportion of cells in the S phase but promoted hormone secretion to a lesser degree. Overall, 122 differentially expressed genes (DEGs) were identified. A total of 51 upregulated and 71 downregulated genes were included. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses indicated that the most DEGs were enriched in terms of cell growth regulation, cell growth, neuroactive ligand-receptor interaction, cytokine-cytokine receptor interaction, the cAMP-signaling pathway, and the Wnt-signaling pathway. Seven genes related to granulosa cell proliferation were screened, IGFBP4, HTRA4, SST, SSTR1, WISP1, DAAM2, and RSPO2. The above results provide molecular theoretical support for NAC as a feed additive to improve follicle development and improve reproductive performance in ewes.

Somatostatin Analogs in Clinical Practice: a Review

Somatostatin analogs are an invaluable therapeutic option in the diagnosis and treatment of somatotropinomas, thyrotropinomas, and functioning and non-functioning gastroenteropancreatic neuroendocrine tumors. They should also be considered an effective and safe therapeutic alternative to corticotropinomas, gonadotropinomas, and prolactinomas resistant to dopamine agonists. Somatostatin analogs have also shown to be useful in the treatment of other endocrine diseases (congenital hyperinsulinism, Graves’ orbitopathy, diabetic retinopathy, diabetic macular edema), non-endocrine tumors (breast, colon, prostate, lung, and hepatocellular), and digestive diseases (chronic refractory diarrhea, hepatorenal polycystosis, gastrointestinal hemorrhage, dumping syndrome, and intestinal fistula).

Estrogens Modulate Somatostatin Receptors Expression and Synergize With the Somatostatin Analog Pasireotide in Prostate Cells

Prostate cancer (PC) is one of the most frequently diagnosed cancers and a leading cause of cancer-related deaths in Western society. Current PC therapies prevalently target the functions of androgen receptor (AR) and may only be effective within short time periods, beyond which the majority of PC patients progress to castration-resistant PC (CRPC) and metastatic disease. The role of estradiol/estradiol receptor (ER) axis in prostate transformation and PC progression is well established. Further, considerable efforts have been made to investigate the mechanism by which somatostatin (SST) and somatostatin receptors (SSTRs) influence PC growth and progression. A number of therapeutic strategies, such as the combination of SST analogs with other drugs, show, indeed, strong promise. However, the effect of the combined treatment of SST analogs and estradiol on proliferation, epithelial mesenchyme transition (EMT) and migration of normal- and cancer-derived prostate cells has not been investigated so far. We now report that estradiol plays anti-proliferative and pro-apoptotic effect in non-transformed EPN prostate cells, which express both ERα and ERβ. A weak apoptotic effect is observed in transformed CPEC cells that only express low levels of ERβ. Estradiol increases, mainly through ERα activation, the expression of SSTRs in EPN, but not CPEC cells. As such, the hormone enhances the anti-proliferative effect of the SST analog, pasireotide in EPN, but not CPEC cells. Estradiol does not induce EMT and the motility of EPN cells, while it promotes EMT and migration of CPEC cells. Addition of pasireotide does not significantly modify these responses. Altogether, our results suggest that pasireotide may be used, alone or in combination with other drugs, to limit the growth of prostate proliferative diseases, provided that both ER isoforms (α and β) are present. Further investigations are needed to better define the cross talk between estrogens and SSTRs as well as its role in PC.

A review of the use of somatostatin analogs in oncology

Somatostatin is a neuropeptide produced by paracrine cells that are located throughout the gastrointestinal tract, lung, and pancreas, and is also found in various locations of the nervous system. It exerts neural control over many physiological functions including inhibition of gastrointestinal endocrine secretion through its receptors. Potent and biologically stable analogs of somatostatin have been developed. These somatostatin analogs show different efficacy on different receptors, and receptors are varyingly concentrated in specific tissues. Antitumor and antisecretory effects of somatostatin analogs in cancer have been shown in several in vivo and in vitro studies. However, these activities have not always yielded into clinically relevant patient outcome benefit. Somatostatin analogs are of clinical benefit in treating symptoms of ectopic hormone secretion (adrenocorticotropic hormone, growth hormone-releasing hormone) in lung cancer, without inducing a significant tumor response. They have also been shown to induce a statistically significant decrease in bone pain and increase in Karnofsky performance status in patients with metastatic prostate cancer. Somatostatin analogs alone or in combination with other agents have only limited antitumoral effect in breast cancer. In gastrointestinal cancers, studies have not shown an objective tumor response to somatostatin analogs except in endocrine tumors of the liver with symptomatic and biochemical improvement. In neuroendocrine tumors of the gastrointestinal system and pancreas, very high symptomatic and biochemical response rates have been achieved with somatostatin analogs. Antiproliferative activity has been clearly shown in metastatic midgut neuroendocrine tumors.

Somatostatin derivative (smsDX) targets cellular metabolism in prostate cancer cells after androgen deprivation therapy

Cancer cell metabolism responsive to androgen deprivation therapy (ADT) may be involved in the development and progression of prostate cancer and the ultimate failure of androgen-deprivation therapy. To investigate the metabolism regulation effects on androgen-independent growth of prostate cancer, an established LNCaP-s cell model that resembles the clinical scenario of castration-resistant prostate cancer (CRPC), was used in this current study. This cell line was cultured from androgen-sensitive LNCaP parental cells, in an androgen-reduced condition, resembling clinical androgen deprivation therapy. To assess the effects of smsDX on the invasiveness of prostate cancer cells we used wound healing assay and Matrigel™ invasion assay. We evaluated differentially expressed proteins of the parental LNCaP cells and LNCaP-s cells after ADT by means of two-dimensional gel electrophoresis (2-DE) followed by MALDI-TOF mass spectrometric analysis. The covered area in the wound and the number of cells invading through a Matrigel chamber were significantly smaller for cells treated with smsDX than they were for control cells treated with vehicle. 56 proteins were found differentially expressed in LNCaP-s cells compared to LNCaP cells, majority of them were down-regulated after ADT treatment. 104 proteins of LNCaP cells and 86 in LNCaP-s cells, separately, were found differentially expressed after treatment with smsDX, When we explored these protein functions within the website UniProtKB/Swiss-Prot, surprisingly, most of the proteins were found to be involved in the cellular metabolism and mitochondrial function regulation. LNCaP-s as potential metastatic androgen-independent cancer cells, its metabolism and mitochondrial functions could be altered by a new somatostatin derivative smsDX, the smsDX regulatory effects on metabolism in LNCaP-s deliver more therapeutic information with the treatment of CRPC.

Somatostatin and somatostatin receptors: implications for neoplastic growth and cancer biology

Somatostatin agonists (SM-As) are capable of achieving durable symptomatic relief and significant clinical responses in certain tumours. Herein, we review the diverse direct and indirect mechanisms of antineoplastic activity elicited by SM-As as well as the hurdles that complicate their use as monotherapies in a broader range of malignancies. Emphasis is placed on recent clinical attempts to neutralise the IGF-mediated survival factor effects in the bone metastasis microenvironment in advanced prostate cancer. The first clinical trials of this 'anti-survival factor manipulation' strategy utilised the ability of SM-As to suppress the growth hormone-dependent liver-derived IGF-I bioavailability in combination with other drugs, such as dexamethasone, zolendronate and oestrogens, acting systemically and at the bone metastasis microenvironment. These regimens restored androgen ablation responsiveness in stage D3 prostate cancer patients and successfully produced objective clinical responses while only mild toxicities were observed. Furthermore, we focus on the preclinical experimental data of a targeted SM-A coupled to the super-potent doxorubicin derivative AN-201. The resulting conjugate (AN-238) has shown increased antitumour potency with a favourable toxicity profile. The potential use of novel SM-As as anticancer drugs is discussed in relation to data suggesting other direct and indirect treatment approaches pertaining to the somatostatin system.