Substance P--a potent risk factor in childhood lymphoblastic leukaemia

Neurological Regulation of the Bone Marrow Niche

The bone marrow (BM) hematopoietic niche is the microenvironment where in the adult hematopoietic stem and progenitor cells (HSPCs) are maintained and regulated. This regulation is tightly controlled through direct cell-cell interactions with mesenchymal stromal stem (MSCs) and reticular cells, adipocytes, osteoblasts and endothelial cells, through binding to extracellular matrix molecules and through signaling by cytokines and hematopoietic growth factors. These interactions provide a healthy environment and secure the maintenance of the HSPC pool, their proliferation, differentiation and migration. Recent studies have shown that innervation of the BM and interactions with the peripheral sympathetic neural system are important for maintenance of the hematopoietic niche, through direct interactions with HSCPs or via interactions with other cells of the HSPC microenvironment. Signaling through adrenergic receptors (ARs), opioid receptors (ORs), endocannabinoid receptors (CRs) on HSPCs and MSCs has been shown to play an important role in HSPC homeostasis and mobilization. In addition, a wide range of neuropeptides and neurotransmitters, such as Neuropeptide Y (NPY), Substance P (SP) and Tachykinins, as well as neurotrophins and neuropoietic growth factors have been shown to be involved in regulation of the hematopoietic niche. Here, a comprehensive overview is given of their role and interactions with important cells in the hematopoietic niche, including HSPCs and MSCs, and their effect on HSPC maintenance, regulation and mobilization.

Neurokinin-1 Receptor Antagonists as Anticancer Drugs

Background::

Human tumor cells lines and tumor samples overexpress the neurokinin-1 receptor (NK-1R). Substance P (SP), after binding to NK-1Rs, induces tumor cell proliferation, an antiapoptotic effect and promotes angiogenesis and the migration of cancer cells for invasion and metastasis.

Methods: :

In contrast, NK-1R antagonists block the previous pathophysiological actions mediated by SP. These antagonists promote the death of tumor cells by apoptosis. Peptide and non-peptide NK-1R antagonists have been reported.

Results: :

Peptide NK-1R antagonists show chemical modifications of the SP molecule (L-amino acids being replaced by D-amino acids), whereas non-peptide NK-1R antagonists include numerous compounds with different chemical compositions while showing similar stereochemical features (affinity for the NK- 1R). Currently, there are more than 300 NK-1R antagonists.

Conclusion::

In combination therapy with classic cytostatics, NK-1R antagonists have additive or synergic effects and minimize the side-effects of cytostatics. The effect of NK-1R antagonists as broad-spectrum anticancer drugs is reviewed and the use of these antagonists for the treatment of cancer is suggested.

Inhibition of tachykinin NK1 receptor using aprepitant induces apoptotic cell death and G1 arrest through Akt/p53 axis in pre-B acute lymphoblastic leukemia cells

Increasing number of genetic and cancer biology studies indicated a prominent role for tachykinin NK₁ receptor (NK₁R) in cancer cell growth and survival. Considering the fact that neoplastic lymphoid precursors in acute lymphoblastic leukemia (ALL) carry a three- to four-fold NK₁R expression as compared to normal lymphocytes, using NK₁R antagonist seems to be noteworthy in the treatment of ALL patients. In this study, we found that inhibition of NK₁R with aprepitant, a selective high-affinity antagonist of the human NK₁R, exerts cytotoxic and anti-proliferative effects against pre-B ALL-derived Nalm-6 cells either as single drug or in combination with doxorubicin. Our data showed that treatment of the cells with the inhibitor resulted in apoptotic cell death, at least partly, through abrogation of PI3K/Akt pathway, as revealed by the reduction of phospho/total Akt ratio. In agreement with the inhibitory effect on Akt, we also found that aprepitant increased the expression level of p21 and p27, which in turn leads to the induction of G1 cell cycle arrest. Overall, this study recommends mechanistic pathways by which inhibition of NK₁R can augment apoptotic cell death through a plausible p53-dependent pathway rather than NF-κB-depended mechanism in pre-B ALL cells; however, further studies are needed to better characterize the application of NK₁R inhibition in clinical cancer treatment.

Association of genetic variants in tachykinins pathway genes with colorectal cancer risk

PURPOSE

This study aims to explore the associations of polymorphisms in tachykinin, precursor 1 (TAC1), tachykinin receptor 1 (TACR1), and tachykinin receptor 2 (TACR2) genes and their interactions with the risk of colorectal cancer (CRC) among Chinese population.

METHODS

A population-based case-control study which included 394 cases and 393 cancer-free controls was carried out. A total of 19 tagSNPs in the three genes were chosen based on HapMap and NCBI datasets and genotyped by SNPshot assay. Multiple logistic regression models were applied to evaluate the associations of SNPs with CRC after adjustment for potential covariates. Furthermore, generalized multifactor dimensionality reduction (GMDR) method was used to test the interactive effect among three genes on CRC.

RESULTS

Compared with those carrying rs3755457 CC/CT or rs12477554 TT/CT genotype, individuals carrying homozygous variants had higher risk of colorectal cancer (adjusted OR = 1.80, 95 % CI = 1.03-3.13, P = 0.039 for rs3755457; adjusted OR = 1.73, 95 % CI = 1.07-2.79, P = 0.024 for rs12477554). As for rs10198644, GG genotype was associated with a 1.72-fold (95 % CI = 0.37-0.88) decreased risk when compared with the common CC genotype. Moreover, the GMDR analysis indicated that the best interactive model included five polymorphisms: rs2072100 (TAC1), rs10198644 (TACR1), rs2193409 (TACR1), rs3771810 (TACR1), and rs4644560 (TACR2).

CONCLUSIONS

Our study suggests that tachykinins pathway genes may participate in the development of CRC and the potential interactions among the three genes on CRC may exist, which has to be confirmed in future larger studies.

Expression and proliferative effect of hemokinin-1 in human B-cells

Tachykinins are a family of structurally related peptides, including substance P (SP), hemokinin-1 (HK-1), neurokinin A (NKA), and neurokinin B. SP and NKA have been shown to modulate hematopoiesis and rat/mouse HK-1 has been found to be involved in the survival and differentiation of mouse B-cells. This study was designed to assess the expression of tachykinins with a focus on human HK-1 (hHK-1) in human B lymphocytes and the role of these peptides in cell differentiation, apoptosis and proliferation. Expression of tachykinin and tachykinin receptor mRNA was determined quantitatively in human B lymphoproliferative malignancies and compared to normal B-cells. Expression of hHK-1 and NK(1) receptor, but not SP, was detected in human B-lymphocytes, and was up-regulated in B-lymphocytes from chronic lymphocytic leukemia and non-Hodgkin's lymphoma, while it was down-regulated in acute lymphoblastic leukemia. Moreover, hHK-1, in contrast to SP, was able to induce proliferation of human pre-B lymphocytes through a NK(1) receptor-independent mechanism. These data suggest a role for hHK-1 in normal and pathological B lymphopoiesis, and open the door to a better understanding of the physiopathological mechanisms leading to lymphoproliferative malignancies.

The NK-1 receptor is expressed in human leukemia and is involved in the antitumor action of aprepitant and other NK-1 receptor antagonists on acute lymphoblastic leukemia cell lines

Substance P and neurokinin-1 (NK-1) receptor antagonists respectively induce cell proliferation and cell inhibition in human cancer cell lines. In acute lymphoblastic leukemia (ALL), substance P is expressed in human blast cells. However, the possible presence of NK-1 receptors in human ALL and the issue of whether the antitumor action of NK-1 receptor antagonists is exerted or not on human ALL (T-ALL BE-13 and B-ALL SD-1 cell lines) remain unknown. An immunoblot analysis was performed and an in vitro study of the cytotoxicity of three NK-1 receptor antagonists (L-733,060, L-732,138, aprepitant) was carried out on both cell lines. NK-1 receptors were found in those cell lines, and both expressed mRNA for this receptor. Using a knockdown method, we demonstrate that NK-1 receptors are involved in the viability of tumor cells. TAC1R cDNA was detected in the ALL cell lines by real-time quantitative RT-PCR. We also observed that the three NK-1 receptor antagonists elicited the inhibition of ALL cell growth; that the specific antitumor action of the NK-1 receptor antagonists occurs through the NK-1 receptor, and that ALL cell death is due to apoptosis. These findings suggest that NK-1 receptor antagonists could be considered as new antitumor drugs for the treatment of human ALL.

In vitro substance P-dependent induction of bone marrow cells in common (CD10) acute lymphoblastic leukaemia

The aim of the present research was to investigate the possible in vitro stimulatory effect of substance P (SP) on blasts induction in childhood common acute lymphoblastic leukaemia (ALL). Bone marrow aspirates were incubated with SP receptor agonist or antagonist (spantide) and subsequently assayed for the presence of human interleukin (IL)-1b using ELISA kit. Blast cells incubated with SP receptor agonist were found to result in a significant increase of IL-1b concentration while incubated with spantide resulted in control levels of IL-1b. These findings suggest the novel possible role of SP in blasts proliferation in childhood ALL of common (CD10) origin.

Tachykinins and Hematopoiesis

Originally discovered in the 1930s, tachykinins have been a subject of renewed interest. Antagonists to the tachykinin receptors have shown potential in the treatment of a variety of maladies including neurodegenerative disorders, heart disease, pain perception and malignancies. Tachykinins have been the subject of intense studies due to their impact on hematopoiesis that has significant effects on endothelial tissue and vascular conditions. Hematopoiesis relies on a relatively small subset of bone marrow-resident hematopoietic stem cells. This review discusses the network developed by cytokines and the tachykinins to regulate hematopoiesis. An understanding of tachykinin effect on normal hematopoietic functions and their involvement in hematological disorders could lead to new treatments for bone marrow disorders such as fibrosis, leukemia and anemia.

The significance of substance P in physiological and malignant haematopoiesis

The role of substance P (SP) in physiological haematopoiesis is well established. However, it also seems to be important in the neoplastic transformation of bone marrow, leading to the development of acute leukaemia in children, and also metastases to bone marrow of solid tumours (particularly neuroblastoma and breast cancer) in early stages of these diseases. This review summarises the available data on SP involvement in both processes. In the future, SP antagonists may be used as anti-neoplastic drugs, for example by direct or indirect blocking of tumour cell proliferation through inhibition of growth factor production and interleukin-1b synthesis.

The predicting role of substance P in the neoplastic transformation of the hypoplastic bone marrow

AIMS

To estimate the expression of substance P in the haematopoietic cells of hypoplastic bone marrow and define its relationship with the course of bone marrow hypoplasia.

METHODS

Bone marrow specimens were obtained from 42 children with bone marrow hypoplasia who were hospitalised in the Department of Pediatric Oncology, Hematology and Transplantology, Poznan University of Medical Sciences, Poznan, Poland, between 1996 and 2003. Substance P and Ki-67 expression were evaluated using immunochemical and hybridocytochemical assays.

RESULTS

The expression of substance P (as evidenced by both immunocytochemical and hybridisation techniques) was confirmed in the cytoplasm of B lymphocytes in 8 of 11 children who developed acute leukaemia in 45 (SD 12) days. The percentage of substance P-positive cells ranged from 67.6 to 95.8 (mean of 81.5% cells with immunocytochemistry and 84.3% with in situ hybridisation). The risk of development of leukaemia secondary to bone marrow hypoplasia was found to be significant (p<0.001) in those children who expressed substance P in normal-looking lymphocytes at the initial bone marrow evaluation.

CONCLUSIONS

The presence of substance P in B lymphocytes of hypoplastic bone marrow may predict its neoplastic transformation. A marked correlation between substance P-positive bone marrow pattern and the expansion of tumour cells may prove the potential value of this oligopeptide in the pathogenesis of leukaemia.

G protein-coupled receptors in haematopoietic disruption

Haematopoiesis is the process by which blood and immune cells are replenished from a finite number of resident bone marrow (BM) haematopoietic stem cells (HSCs). Regulatory molecules within the BM microenvironment contribute developmental signals to an interactive network capable of ensuring ordered biological processes. Many bioactive molecules contribute to the network through G protein-coupled receptors (GPCRs). GPCRs are seven-transmembrane receptors that, following ligand binding, signal by activating coupled heterotrimeric G proteins. This review focuses on those bioactive molecules that regulate haematopoietic development through GPCRs. Chemokines (SDF-1alpha, MIP-1), opioids and tachykinins (SP, NK-A) are important G protein-coupled haematopoietic regulators. Their biology in normal and diseased haematopoiesis is discussed below, as well as their potential as therapeutic targets.

Substance-P-mediated immunomodulation of tumor growth in a murine model

BACKGROUND/OBJECTIVE

Substance P (SP) has been reported to have immunoregulatory properties including effects on many of the mediators involved in anti-tumor immunity. In this study, we investigated the effect of SP on tumor development in a murine model of melanoma. In addition, we examined the role of natural killer (NK) and T cells in SP-mediated modulation of tumor growth.

MATERIALS AND METHODS

Mice were implanted with mini-osmotic pumps that delivered a continuous infusion of either SP or PBS over a 14-day period. Five days following implantation, animals received K1735 melanoma cells and tumor growth was monitored. The role of NK and T cells in SP-mediated protection was examined by antibody depletion studies. To determine if cells from SP-treated animals could delay tumor growth in animals in the absence of exogenous SP infusion, splenocytes from mice treated with SP were adoptively transferred into SCID mice.

RESULTS

In vivoSP treatment led to a significant delay in tumor growth. When animals were depleted of NK or T cells, this protective effect was lost. Adoptive transfer of cells from SP-treated animals led to a significant protective effect on tumor growth in SCID mice.

CONCLUSION

Pretreatment of mice with SP provides protection against K1735 tumor growth, and this protection requires both T cells and NK cells. SP-mediated tumor protection can be transferred by the adoptive transfer of cells from SP-treated animals into animals that do not receive exogenous SP. These studies suggest a model in which in vivo SP treatment prior to tumor challenge primes immune mediators to prevent or delay tumor establishment.