Neuropeptides stimulate tyrosine phosphorylation and tyrosine kinase activity in small cell lung cancer cell lines

Role of Focal Adhesion Kinase in Small-Cell Lung Cancer and Its Potential as a Therapeutic Target

Small-cell lung cancer (SCLC) represents 15% of all lung cancers and it is clinically the most aggressive type, being characterized by a tendency for early metastasis, with two-thirds of the patients diagnosed with an extensive stage (ES) disease and a five-year overall survival (OS) as low as 5%. There are still no effective targeted therapies in SCLC despite improved understanding of the molecular steps leading to SCLC development and progression these last years. After four decades, the only modest improvement in OS of patients suffering from ES-SCLC has recently been shown in a trial combining atezolizumab, an anti-PD-L1 immune checkpoint inhibitor, with carboplatin and etoposide, chemotherapy agents. This highlights the need to pursue research efforts in this field. Focal adhesion kinase (FAK) is a non-receptor protein tyrosine kinase that is overexpressed and activated in several cancers, including SCLC, and contributing to cancer progression and metastasis through its important role in cell proliferation, survival, adhesion, spreading, migration, and invasion. FAK also plays a role in tumor immune evasion, epithelial-mesenchymal transition, DNA damage repair, radioresistance, and regulation of cancer stem cells. FAK is of particular interest in SCLC, being known for its aggressiveness. The inhibition of FAK in SCLC cell lines demonstrated significative decrease in cell proliferation, invasion, and migration, and induced cell cycle arrest and apoptosis. In this review, we will focus on the role of FAK in cancer cells and their microenvironment, and its potential as a therapeutic target in SCLC.

CD133+ cancer stem-like cells in small cell lung cancer are highly tumorigenic and chemoresistant but sensitive to a novel neuropeptide antagonist

Small cell lung cancer (SCLC) is a highly aggressive malignancy with poor survival rates, with initial responses nearly invariably followed by rapid recurrence of therapy-resistant disease. Drug resistance in SCLC may be attributable to the persistence of a subpopulation of cancer stem-like cells (CSC) that exhibit multiple drug resistance. In this study, we characterized the expression of CD133, one important marker of CSC in other cancers, in SCLC cancer cells. CD133 expression correlated with chemoresistance and increased tumorigenicity in vitro and in vivo accompanied by increased expression of Akt/PKB and Bcl-2. CD133 expression was increased in mouse and human SCLC after chemotherapy, an observation confirmed in clinical specimens isolated longitudinally from a patient receiving chemotherapy. We discovered in CD133(+) SCLC cells, an increased expression of the mitogenic neuropeptide receptors for gastrin-releasing peptide and arginine vasopressin. Notably, these cells exhibited increased sensitivity to the growth inhibitory and proapoptotic effects of a novel broad spectrum neuropeptide antagonist (related to SP-G), which has completed a phase I clinical trial for SCLC. Our results offer evidence that this agent can preferentially target chemoresistant CD133(+) cells with CSC character in SCLC, emphasizing its potential utility for improving therapy in this setting.

Investigation of proNT/NMN secretion from small cell lung carcinoma cells using a mouse xenograft model

Proneurotensin/neuromedin N (proNT/NMN), the precursor of neurotensin (NT) and neuromedin N (NMN), is produced by cancer tissues derived from the pancreas and colon. NT stimulates tumor growth and proliferation through its receptors; however, little is known about the precursor molecule in cancer tissues. We previously demonstrated that proNT/NMN is secreted from small cell lung carcinoma (SCLC) cell lines in serum-free conditioned medium, but not from non-small cell lung carcinoma (NSCLC) cell lines. It was suggested that this precursor may serve as a tumor marker for SCLC. In this study, we established in vivo xenograft models to evaluate the possibility of proNT/NMN as a specific tumor marker. SBC3 cells, derived from human SCLC, were inoculated into mice, and the proNT/NMN levels in plasma and tumor tissues were detected using specific antibodies. In contrast to control mouse plasma, the proNT/NMN levels in tumor-bearing mice increased as the tumors grew, and the elevated plasma proNT/NMN levels were decreased by tumor resection. Moreover, proNT/NMN was expressed in SBC3 tumors, suggesting that proNT/NMN was secreted into blood from the tumor, and this secretion may be specific to SCLC.

Neurotensin and its high affinity receptor 1 as a potential pharmacological target in cancer therapy

Cancer is a worldwide health problem. Personalized treatment represents a future advancement for cancer treatment, in part due to the development of targeted therapeutic drugs. These molecules are expected to be more effective than current treatments and less harmful to normal cells. The discovery and validation of new targets are the foundation and the source of these new therapies. The neurotensinergic system has been shown to enhance cancer progression in various cancers such as pancreatic, prostate, lung, breast, and colon cancer. It also triggers multiple oncogenic signaling pathways, such as the PKC/ERK and AKT pathways. In this review, we discuss the contribution of the neurotensinergic system to cancer progression, as well as the regulation and mechanisms of the system in order to highlight its potential as a therapeutic target, and its prospect for its use as a treatment in certain cancers.

The potential use of the neurotensin high affinity receptor 1 as a biomarker for cancer progression and as a component of personalized medicine in selective cancers

A growing challenge in medicine today, is the need to improve the suitability of drug treatments for cancer patients. In this field, biomarkers have become the "flags" to provide additional information in tumor biology. They are a relay between the patient and practitioner and consequently, aid in the diagnosis, providing information for prognosis, or in some cases predicting the response to specific therapies. In addition to being markers, these tumor "flags" can also be major participants in the process of carcinogenesis. Neurotensin receptor 1 (NTSR1) was recently identified as a prognosis marker in breast, lung, and head and neck squamous carcinomas. Neurotensin (NTS) was also shown to exert numerous oncogenic effects involved in tumor growth and metastatic spread. These effects were mostly mediated by NTSR1, making the NTS/NTSR1 complex an actor in cancer progression. In this review, we gather information on the oncogenic effects of the NTS/NTSR1 complex and its associated signaling pathways in order to illuminate its significant role in tumor progression and its potential as a biomarker and a therapeutic target in some tumors.

Loss of sympathetic nerve fibers around intratumoral arterioles reflects malignant potential of gastric cancer

BACKGROUND

The role and clinical significance of the alteration of sympathetic nerve fibers (SNF) was assessed in gastric cancer. Loss of nerve fibers in malignant tumors has previously been described; however, how dysfunction of the nervous system is involved in cancer progression has not been clarified in clinical studies.

MATERIALS AND METHODS

The distribution of SNF was examined in 82 surgically resected gastric cancer specimens with immunohistochemical staining of tyrosine hydroxylase (TH), and the association with clinicopathological findings as well as the clinical outcome of the patients was retrospectively evaluated.

RESULTS

Arterioles in the normal gastric wall were totally covered with SNF, while the immunoreactivity to TH was markedly reduced around arterioles in cancer tissue. The degree of loss of SNF was significantly correlated with the depth of invasion (P < .0001) and lymph node metastasis (P < .0001) as well as microvessel density (MVD) (P = .0043). Moreover, patients who had tumors with marked loss of SNF showed a markedly worse clinical outcome, with an independent association by multivariate analysis.

CONCLUSIONS

Loss of periarteriolar SNF is associated with aggressive phenotype of gastric cancer possibly through enhanced angiogenesis and thus could be a useful marker to predict the clinical outcome.

Involvement of neurotensin in cancer growth: evidence, mechanisms and development of diagnostic tools

Focusing on the literature of the past 15 years, we evaluate the evidence that neurotensin and neurotensin receptors participate in cancer growth and we describe possible mechanisms. In addition, we review the progress achieved in the use of neurotensin analogs to image tumors in animals and humans. These exciting advances encourage us to pursue further research and stimulate us to consider novel ideas regarding the multiple inputs to cancer growth that neurotensin might influence.

Characterization of the B2 receptor and activity of bradykinin analogs in SHP-77 cell line by Cytosensor microphysiometer

The Cytosensor microphysiometer device (Molecular Devices, Sunnyvale, CA) is capable of measuring the rate at which cells acidify their environment in response to ligand-receptor binding. By measuring the extracellular acidification response (ECAR) we characterized some aspects of ligand-B2 receptor interaction in SHP-77 cell line. SHP-77 cells maximally acidified their environment within 30 s after the exposure to bradykinin (BK) or the BK agonist, B9972, with the maximum effect seen at a ligands concentration of 1 microM. Fetal bovine serum (FBS) modulated the binding of BK or B9972, showing that B9972 is a partial agonist. In addition, the binding of BK agonist or antagonist to the B2 receptor showed different ECAR and different interaction with other intracellular and plasma membrane proteins. Our microphysiometrical results showed that two parameters, antagonist binding affinity (pD2) and antagonist potency (pIC50) are required to characterize BK antagonist activity for the B2 receptor in the SHP-77 cell line. The previously used parameter of B2 antagonist activity, pA2, had high variation and poor correlation with the inhibition of SHP-77 cell growth in vitro and suppression of tumor growth when SHP-77 cells were injected to mice. Our results permit us to conclude that BK agonists and antagonists differ in their interactions with the B2 receptor and consequently elicit different cell responses. Based on our results, we have developed a new microphysiometrical assay for analyzing the activity of BK agonists and antagonist in SHP-77 cells, which may facilitate the discovery of new potent anticancer drugs.

Increased gastrin-releasing peptide (GRP) receptor expression in tumour cells confers sensitivity to [Arg6,D-Trp7,9,NmePhe8]-substance P (6-11)-induced growth inhibition

[Arg(6),D-Trp(7,9),N(me)Phe(8)]-substance P (6-11) (SP-G) is a novel anticancer agent that has recently completed phase I clinical trials. SP-G inhibits mitogenic neuropeptide signal transduction and small cell lung cancer (SCLC) cell growth in vitro and in vivo. Using the SCLC cell line series GLC14, 16 and 19, derived from a single patient during the clinical course of their disease and the development of chemoresistance, it is shown that there was an increase in responsiveness to neuropeptides. This was paralleled by an increased sensitivity to SP-G. In a selected panel of tumour cell lines (SCLC, non-SCLC, ovarian, colorectal and pancreatic), the expression of the mitogenic neuropeptide receptors for vasopressin, gastrin-releasing peptide (GRP), bradykinin and gastrin was examined, and their sensitivity to SP-G tested in vitro and in vivo. The tumour cell lines displayed a range of sensitivity to SP-G (IC(50) values from 10.5 to 119 microM). The expression of the GRP receptor measured by reverse transcriptase-polymerase chain reaction, correlated significantly with growth inhibition by SP-G. Moreover, introduction of the GRP receptor into rat-1A fibroblasts markedly increased their sensitivity to SP-G. The measurement of receptor expression from biopsy samples by polymerase chain reaction could provide a suitable diagnostic test to predict efficacy to SP-G clinically. This strategy would be of potential benefit in neuropeptide receptor-expressing tumours in addition to SCLC, and in tumours that are relatively resistant to conventional chemotherapy.