Stem cell factor/c-kit signaling enhances invasion of pancreatic cancer cells via HIF-1α under normoxic condition.

The SCF/c-kit signaling plays an important role in invasion of c-kit-expressing tumor cells, however, the molecular mechanisms have not been studied yet. Using a pancreatic cancer model, we demonstrate that SCF/c-kit binding up-regulates the expression of invasion-related genes through the accumulation of HIF-1α. Furthermore, the expression of HIF-1α induced by SCF is not dependent on the oxygen level, but rather on both the PI3K/Akt and Ras/MEK/ERK signaling pathways. In conclusion, under normoxic conditions, SCF/c-kit binding increases expression of HIF-1α through the PI3K/Akt and Ras/MEK/ERK pathways, and the accumulation of HIF-1α up-regulates expression of invasion-related genes that augment the invasiveness of pancreatic cancer, a fatal cancer. Therefore, our results suggest that the inhibition of both c-kit and HIF-1α may be an effective strategy for pancreatic cancer therapy.

ß2-adrenergic antagonists suppress pancreatic cancer cell invasion by inhibiting CREB, NFκB and AP-1.

Smoking and chronic stress are well-documented risk factors that are associated with ß-adrenoceptors in the development of pancreatic cancer. Stimulation of ß-adrenoceptors can activate cyclic adenosine monophosphate (cAMP)/ protein kinase A (PKA) and mitogen-activated protein kinase (MAPK) pathways in pancreatic cancer cells. Many recent studies have focused on the function of ß-adrenoceptors in cancer invasion. Thus, we hypothesized that ß-adrenoceptors may play a role in pancreatic cancer invasion, and ß-blockers may suppress the pancreatic cancer invasion and proliferation. MIA PaCa-2 and BxPC-3 cell lines express mRNA and protein of both ß1 and ß2-adrenoceptors. ß2-adrenergic antagonist ICI118,551 and ß1/2-adrenergic antagonist propranolol significantly suppressed cell invasion and proliferation in comparison to ß1-adrenergic antagonist metoprolol and control in a Matrigel invasion assay and subrenal capsular assay. Treatment with ß2-adrenoceptor antagonists inhibited activation of transcription factors nuclear factor κB (NF-κB), activator protein 1 (AP-1) and cAMP response element binding protein (CREB) as demonstrated by electrophoretic mobility shift assays and Western blotting. ß2-adrenoceptor antagonists also significantly altered vascular endothelial growth factor (VEGF), cyclooxygenase-2 (COX-2), matrix metalloproteinase 2 (MMP-2) and MMP-9 expression. The ß2-adrenergic antagonists suppressed invasion and proliferation by inhibiting both cAMP/PKA and Ras, which regulate activation of the MAPK pathway and transcription factors, such as NF-κB, AP-1 and CREB, as well as expression of its target genes, MMP-9, MMP-2 and VEGF. However, ß1-adrenergic antagonists suppressed invasion by inhibiting only the cAMP/PKA pathway, suggesting that they may be useful as novel preventive and therapeutic strategies for pancreatic cancer.

Targeting the L-arginine-nitric oxide pathway for cancer treatment.

The action of L-arginine is mainly dependent on its end-product, nitric oxide (NO). The L-arginine/NO pathway has been confirmed to play an important role in tumor development. Recent findings indicate that NO derived from L-arginine could influence angiogenesis factors, vascular permeability, perivascular-cell recruitment and vessel remodeling and maturation. Additionally, the L-arginine/NO pathway could activate a broad array of genes that are functionally involved in proliferation, metastasis and apoptosis. Interestingly, this pathway plays roles in both tumorigensis and tumor killing. The role of the L-arginine/NO pathway in tumor therapy has been well-studied. Members of this pathway have been reported to be promising therapeutic molecules in tumor therapy. This review article summarizes research data on the roles of the L-arginine/NO pathway in cancer biology and cancer therapy.

HIF-1alpha links beta-adrenoceptor agonists and pancreatic cancer cells under normoxic condition.

AIM: To examine whether beta-adrenoceptor (beta-AR) agonists can induce hypoxia-inducible factor (HIF)-1alpha accumulation which then up-regulate the expression of its target genes in pancreatic cancer cells at normoxia, and to further elucidate the mechanism involved. METHODS: Pulse-chase assay, RT-PCR, and Western blot were employed to detect the effects of beta-AR agonists and antagonists, siRNA as well as several inhibitors of signal transduction pathways on MIA PaCa2 and BxPC-3 pancreatic cancer cells. RESULTS: Treatment of pancreatic cancer cell lines with beta-AR agonists led to accumulation of HIF-1alpha and then up-regulated expression of its target genes independently of oxygen levels. The induction was partly or completely inhibited not only by beta-AR antagonists but also by inhibitors of PKA transduction pathways and by siHIF-1alpha. Both beta1-AR and beta2-AR agonists produced the above-mentioned effects, but beta2-AR agonist was more potent. CONCLUSION: Activation of beta-AR receptor transactivates epidermal growth factor receptor (EGFR) and then elicits Akt and ERK1/2 in a PKA-dependent manner, which together up-regulate levels of HIF-1alpha and downstream target genes independently of oxygen level. Our data suggest a novel mechanism in pancreatic cancer cells that links beta-AR and HIF-1alpha signaling under normoxic conditions, with implications for the control of glucose transport, angiogenesis and metastasis.

Norepinephrine-induced invasion by pancreatic cancer cells is inhibited by propranolol.

Active migration and invasion by cancer cells are a prerequisite for the development of metastases. Recent studies have shown that neurotransmitters are involved in the regulation of cancer cell invasion via beta-adrenoceptors (beta-ARs). However, little is known regarding the effect of neurotransmitters on pancreatic cancer cells. The aim of our study was to examine the regulative effect of norepinephrine (NE), which belongs to the group of classical neurotransmitters, on the invasiveness of pancreatic cancer cells and the therapeutic effect of the beta-blocker, propranolol, on them. The human pancreatic cancer cell lines, Miapaca-2 and Bxpc-3, were selected for this study, and in both cell lines, beta1-AR and beta2-AR expression was determined by RT-PCR and Western blotting. The invasiveness of pancreatic cancer cells was examined using the Matrigel invasion assay. The concentrations of MMP-2, MMP-9, and VEGF in the culture medium and in the cancer cells were examined by ELISA and RT-PCR, respectively. We observed that NE promoted the invasiveness of Miapaca-2 cells in a concentration-dependent manner, and NE increased the expression of MMP-2, MMP-9, and VEGF. However, these effects could be inhibited by the beta-blocker, propranolol. In conclusion, the development of metastases is not only genetically determined, but is also influenced by NE, which is one of the signal substances present in the tumor environment. This study also provides experimental evidence for the use of beta-blockers in the chemoprevention of pancreatic cancer metastasis.

Inhibition of pancreatic cancer cell proliferation by propranolol occurs through apoptosis induction: the study of beta-adrenoceptor antagonist's anticancer effect in pancreatic cancer cell.

OBJECTIVES: Propranolol inhibited pancreatic cancer cell proliferation by blocking signaling through the beta-adrenoceptor. We hypothesized that propranolol may suppress pancreatic cancer cell growth through induction of apoptosis. METHODS: The beta-adrenoceptor antagonist propranolol, beta1-adrenoceptor antagonist metoprolol, and beta2-adrenoceptor antagonist butoxamine were used to induce apoptosis in PC-2 cells. The mRNA and protein expression of beta1- and beta2-adrenoceptors was analyzed using reverse transcriptase-polymerase chain reaction and Western blot. The apoptotic index was determined using Hoechst 33342 fluorescent staining, TUNEL, and annexin V and fluorescein isothiocyanate/propidium iodide flow cytometry assay. The expression of caspase 3, caspase 9, and caspase 8 was analyzed using Western blotting. RESULTS: PC-2 cell line expressed mRNA and protein for both of beta1- and beta2-adrenoceptors. The Hoechst staining, TUNEL, and flow cytometry assay documented that the 3 drugs increased the number of apoptotic cells; the rate of apoptosis was the highest using butoxamine followed by propranolol, whereas the least was using metoprolol. beta-Adrenoceptor antagonists therapy affected caspase 3 and caspase 9 expression. CONCLUSIONS: The rate of apoptosis in PC-2 cells was higher after treatment with butoxamine than propranolol, suggesting that propranolol induces apoptosis in PC-2 cells via the beta2-adrenoceptors principally. Our data could be useful for developing beta-adrenoceptor antagonists for inducing apoptosis in pancreatic cancer cells.

Stimulation of dorsal root ganglion neurons activity by pancreatic cancer cell lines.

Stimulation of mice dorsal root ganglion neurons (DRGNs) activity by human pancreatic cancer (PanCa) cell line Mia PaCa-2 and its potential molecule mechanism has been investaged. DRGNs were cultured alone or along with the MIA PaCa-2. The effects of MIA PaCa-2 to DRGNs were determined by neurofilament (NF) immunocytochemical and Nissl staining. ELISA was used to detect the concentration of insulin-like growth factor-1 (IGF-1) in the culture supernatant. Cyton size, neurite outgrowth and neuronal activity in the experimental group were greater than in the control groups. However, the concentration of IGF-1 in the supernatants was not significantly different from those in the blank and non-cultured medium groups. In the presence of MIA PaCa-2 cell line, cyton size, neurite outgrowth and neuronal activity were enhanced, which may provide more routes for the invasion of cancer cells along nerves.

Effects of alpha-adrenoreceptor antagonists on apoptosis and proliferation of pancreatic cancer cells in vitro.

AIM: To discuss the expression of alpha-adrenoreceptors in pancreatic cancer cell lines PC-2 and PC-3 and the effects of alpha1- and alpha2-adrenoreceptor antagonists, yohimbine and urapidil hydrochloride, on the cell lines in vitro. METHODS: We cultured the human ductal pancreatic adenocarcinoma cell lines PC-2 and PC-3 and analyzed the mRNA expression of alpha1- and alpha2-adrenergic receptors by reverse transcription polymerase chain reaction (RT-PCR). The effects of yohimbine and urapidil hydrochloride on cell proliferation were assessed by 3-(4,5-dimethylthiasol-2-yl)-2,4,-diphenyltetrazolium bromide (MTT) assay. Apoptosis was detected using the terminal deoxyribonucleotidyl transferase (TdT)-mediated biotin-16-dUTP nick-end labeling (TUNEL) assay and flow cytometry (FCM). RESULTS: PC-2 expressed mRNA in alpha1- and alpha2-adrenoreceptors. MTT assays showed that urapidil hydrochloride had no effect on PC-3 cell lines. However, exposure to urapidil hydrochloride increased DNA synthesis in PC-2 cell lines as compared to the control group. PC-2 cell lines were sensitive to both drugs. The proliferation of the 2 cell lines was inhibited by yohimbine. Cell proliferation was inhibited by yohimbine via apoptosis induction. CONCLUSION: The expression of alpha1- and alpha2-adrenoreceptors is different in PC-2 and PC-3 cell lines, which might be indicative of their different functions. The alpha2-adrenoceptor antagonist, yohimbine, can inhibit the proliferation of both cell lines and induce their apoptosis, suggesting that yohimbine can be used as an anticancer drug for apoptosis of PC-2 and PC-3 cells.

Analysis of variabilities of serum proteomic spectra in patients with gastric cancer before and after operation.

AIM: To study the variabilities of serum proteomic spectra in patients with gastric cancer before and after operation in order to detect the specific protein markers that can be used for quick diagnosis of gastric cancer. METHODS: Proteomic spectra of 46 serum samples from patients with gastric cancer before and after operation and 40 from normal individuals were generated by IMAC-Cu protein chip and surface-enhanced laser desorption/ ionization time of flight mass spectrometry. RESULTS: Fourteen differentially expressed proteins in serum were screened by analysis of proteomic spectra of preoperative patients and normal individuals. We obtained 4 proteins (heat shock protein 27, glucose-regulated protein, prohibitin, protein disulfide isomerase A3) making up marker pattern which was able to class the patient-team and normal-team. These marker patterns yielded 95.7% sensitivity and 92.5% specificity, respectively. The proteins over-expressed in serum of preoperative patients were obviously down-regulated. CONCLUSION: Specific protein markers of gastric cancer can be used for the quick diagnosis of gastric cancer and judgment of prognosis. SELDI-TOF-MS is a useful tool for the detection and identification of new protein markers in serum.