Metastatic Pancreatic Adenocarcinoma After Total Pancreatectomy Islet Autotransplantation for Chronic Pancreatitis.

Total pancreatectomy with islet autotransplantation (TPIAT) is being used increasingly as a definitive treatment for chronic pancreatitis. Patients with chronic pancreatitis have an elevated risk of pancreatic cancer, which can also masquerade as acute or chronic pancreatitis, making the diagnosis challenging. We describe here the first case of pancreatic ductal adenocarcinoma developing in the liver of a patient after TPIAT for presumed benign chronic pancreatitis. Retrospective analysis of the patient's preoperative serum revealed normal carbohydrate antigen 19-9 and carcinoembryonic antigen levels but elevated levels of microRNAs -10b, -30c, and -106b compared with controls. Screening guidelines are important to reduce the risk of transplantation of malignant tissue. More sensitive screening tools, including the potential use of microRNAs, are needed to detect early preclinical disease, given the highly malignant nature of pancreatic cancer.

Neoadjuvant cetuximab, twice-weekly gemcitabine, and intensity-modulated radiotherapy (IMRT) in patients with pancreatic adenocarcinoma.

BACKGROUND: Neoadjuvant therapy has been investigated for localized and locally advanced pancreatic ductal adenocarcinoma (PDAC) but no standard of care exists. Combination cetuximab/gemcitabine/radiotherapy demonstrates encouraging preclinical activity in PDAC. We investigated cetuximab with twice-weekly gemcitabine and intensity-modulated radiotherapy (IMRT) as neoadjuvant therapy in patients with localized or locally advanced PDAC. EXPERIMENTAL DESIGN: Treatment consisted of cetuximab load at 400 mg/m(2) followed by cetuximab 250 mg/m(2) weekly and gemcitabine 50 mg/m(2) twice-weekly given concurrently with IMRT to 54 Gy. Following therapy, patients were considered for resection. RESULTS: Thirty-seven patients were enrolled with 33 assessable for response. Ten patients (30%) manifested partial response and 20 (61%) manifested stable disease by RECIST. Twenty-five patients (76%) underwent resection, including 18/23 previously borderline and 3/6 previously unresectable tumors. Twenty-three (92%) of these had negative surgical margins. Pathology revealed that 24% of resected tumors had grade III/IV tumor kill, including two pathological complete responses (8%). Median survival was 24.3 months in resected patients. Outcome did not vary by epidermal growth factor receptor status. CONCLUSIONS: Neoadjuvant therapy with cetuximab/gemcitabine/IMRT is tolerable and active in PDAC. Margin-negative resection rates are high and some locally advanced tumors can be downstaged to allow for complete resection with encouraging survival. Pathological complete responses can occur. This combination warrants further investigation.

Pancreatic islet-acinar cell interaction: amylase messenger RNA levels ar determined by insulin.

Pancreatic amylase messenger RNA progressively decreases in rats rendered diabetic with streptozotocin. Insulin reverses this effect, inducing a selective decrease in amylase messenger RNA in the pancreas. Parotid amylase messenger RNA is not significantly affected by either diabetes or insulin.

Estrogen binding, receptor mRNA, and biologic response in osteoblast-like osteosarcoma cells.

High specific activity estradiol labeled with iodine-125 was used to detect approximately 200 saturable, high-affinity (dissociation constant approximately equal to 1.0 nM) nuclear binding sites in rat (ROS 17/2.8) and human (HOS TE85) clonal osteoblast-like osteosarcoma cells. Of the steroids tested, only testosterone exhibited significant cross-reactivity with estrogen binding. RNA blot analysis with a complementary DNA probe to the human estrogen receptor revealed putative receptor transcripts of 6 to 6.2 kilobases in both rat and human osteosarcoma cells. Type I procollagen and transforming growth factor-beta messenger RNA levels were enhanced in cultured human osteoblast-like cells treated with 1 nM estradiol. Thus, estrogen can act directly on osteoblasts by a receptor-mediated mechanism and thereby modulate the extracellular matrix and other proteins involved in the maintenance of skeletal mineralization and remodeling.

Inhibition of basal and mitogen-stimulated pancreatic cancer cell growth by cyclin D1 antisense is associated with loss of tumorigenicity and potentiation of cytotoxicity to cisplatinum.

Cyclin D1 belongs to a family of protein kinases that have been implicated in cell cycle regulation. Recent studies have demonstrated that elevated cyclin D1 levels correlate with decreased survival in human pancreatic cancer. In this study we expressed in a stable manner a cyclin D1 antisense cDNA construct in PANC-1 human pancreatic cancer cells. Expression of the antisense construct caused a decrease in cyclin D1 mRNA and protein levels and in cyclin D1-associated kinase activity. Antisense expressing clones displayed significantly increased doubling times, decreased anchorage-dependent and -independent basal growth, and complete loss of tumorigenicity in nude mice. EGF, FGF-2, and IGF-I enhanced mitogen-activated protein kinase activity in antisense expressing clones, but failed to stimulate their proliferation. In contrast, all three growth factors were mitogenic in parental cells. Furthermore, the inhibitory effect of cisplatinum on cell proliferation was enhanced markedly in the antisense expressing clones. These findings indicate that cyclin D1 overexpression contributes to abnormal growth and tumorigenicity in human pancreatic cancer and to the resistance of pancreatic cancer to chemotherapeutic agents.

Overexpression of the epidermal growth factor receptor in human pancreatic cancer is associated with concomitant increases in the levels of epidermal growth factor and transforming growth factor alpha.

The epidermal growth factor (EGF) receptor is activated by both EGF and transforming growth factor-alpha (TGF-alpha). Using immunohistochemical and immunoblotting techniques we now report that the EGF receptor, EGF, and TGF-alpha are found in both pancreatic acini and ducts in the normal human pancreas, and that all three proteins are expressed at higher levels in human pancreatic cancer tissues. Using in situ hybridization techniques, we also report that the mRNA encoding the EGF receptor, EGF, and TGF-alpha colocalize with their respective proteins. Northern blot analysis of total RNA indicates that, by comparison with the normal pancreas, the pancreatic tumors exhibit a 3-, 15-, and 10-fold increase in the mRNA levels encoding the EGF receptor, EGF, and TGF-alpha, respectively. Furthermore, by in situ hybridization, there is a marked increase in these mRNA moieties within the tumor mass. These findings suggest that EGF and TGF-alpha may participate in the regulation of normal pancreatic exocrine function, and that overexpression of the EGF receptor and its two principal ligands may contribute to the pathophysiological processes that occur in human pancreatic cancer.

The cell-surface heparan sulfate proteoglycan glypican-1 regulates growth factor action in pancreatic carcinoma cells and is overexpressed in human pancreatic cancer.

Heparan sulfate proteoglycans (HSPGs) play diverse roles in cell recognition, growth, and adhesion. In vitro studies suggest that cell-surface HSPGs act as coreceptors for heparin-binding mitogenic growth factors. Here we show that the glycosylphosphatidylinositol- (GPI-) anchored HSPG glypican-1 is strongly expressed in human pancreatic cancer, both by the cancer cells and the adjacent fibroblasts, whereas expression of glypican-1 is low in the normal pancreas and in chronic pancreatitis. Treatment of two pancreatic cancer cell lines, which express glypican-1, with the enzyme phosphoinositide-specific phospholipase-C (PI-PLC) abrogated their mitogenic responses to two heparin-binding growth factors that are commonly overexpressed in pancreatic cancer: fibroblast growth factor 2 (FGF2) and heparin-binding EGF-like growth factor (HB-EGF). PI-PLC did not alter the response to the non-heparin-binding growth factors EGF and IGF-1. Stable expression of a form of glypican-1 engineered to possess a transmembrane domain instead of a GPI anchor conferred resistance to the inhibitory effects of PI-PLC on growth factor responsiveness. Furthermore, transfection of a glypican-1 antisense construct attenuated glypican-1 protein levels and the mitogenic response to FGF2 and HB-EGF. We propose that glypican-1 plays an essential role in the responses of pancreatic cancer cells to certain mitogenic stimuli, that it is relatively unique in relation to other HSPGs, and that its expression by pancreatic cancer cells may be of importance in the pathobiology of this disorder.

microRNA-10b enhances pancreatic cancer cell invasion by suppressing TIP30 expression and promoting EGF and TGF-ß actions.

This corrects the article DOI: 10.1038/onc.2013.405.

Growth inhibition of a human colorectal carcinoma cell line by interleukin 1 is associated with enhanced expression of gamma-interferon receptors.

Recombinant human tumor necrosis factor and recombinant human gamma interferon (IFN-gamma) exert synergistic growth inhibitory effects in WiDR human colorectal carcinoma cells. In this cell line, tumor necrosis factor increases IFN-gamma binding. Interleukin 1 (IL-1) is a cytokine that mimics many of the biological actions of TNF. Therefore, in the present study, we investigated the effects of recombinant human IL-1 on cell growth and IFN-gamma receptor expression in WiDR cells. IL-1 slightly inhibited the growth of WiDR cells, and exerted additive growth inhibitory effects in the presence of IFN-gamma. IL-1 caused a time- and dose-dependent increase in 125I-labeled IFN-gamma binding that was maximal at 6 h, persisted for at least 24 h, and was blocked by both actinomycin D and cycloheximide. The increase in binding was associated with an increase in cell surface IFN-gamma receptor protein expression as determined by Scatchard analysis of equilibrium binding data and by immunofluorescent staining with an anti-human IFN-gamma receptor monoclonal antibody. IL-1 also produced a time- and dose-dependent increase in IFN-gamma receptor mRNA levels that was maximal at 3 h and persisted for at least 24 h. Actinomycin D, but not cycloheximide, completely blocked the IL-1-mediated increase in IFN-gamma receptor mRNA levels. However, IL-1 did not alter IFN-gamma receptor mRNA half-life. These data indicate that IL-1 and IFN-gamma exert additive growth inhibitory effects on colon cancer cell growth, and suggest that IL-1 increases IFN-gamma receptor expression in these cells by enhancing IFN-gamma mRNA levels.

Inhibition of epidermal growth factor binding in rat pancreatic acini by palmitoyl carnitine: evidence for Ca2+ and protein kinase C independent regulation.

D,L-Palmitoyl carnitine (PC), an inhibitor of protein kinase C, decreased [125I]epidermal growth factor (EGF) cell-associated radioactivity in rat pancreatic acini. H-7, another inhibitor of protein kinase C, failed to inhibit [125I]EGF binding. Palmitate, carnitine, acetylcarnitine, and 2-tetradecylglycidic acid methyl ester (a specific inhibitor of endogenous PC formation) did not alter [125I]EGF binding. PC conjugated to bovine serum albumin (PC-BSA) decreased [125I]EGF cell-associated radioactivity to the same extent as PC. Neither compound affected the distribution of cell-associated radioactivity into acid-resistant and acid-dissociable compartments. In contrast, cholecystokinin octapeptide (CCK8) and 12-O-tetradecanoyl-phorbol-13-acetate (TPA) markedly inhibited the distribution of [125I]EGF into the acid-resistant compartment. Proglumide, a competitive antagonist of CCK8, reversed the inhibitory action of CCK8 but not that of PC-BSA. PC-BSA did not inhibit [125I]insulin binding, and did not enhance amylase release, a Ca2+-mediated effect. Further, its inhibitory effect on [125I]EGF cell-associated radioactivity was not additive with the inhibitory effect of the calcium ionophore A23187. Both PC-BSA and H-7 inhibited Ca2+- and phospholipid-dependent kinase activity in soluble and particulate fractions when added to disrupted acini, but in the particulate compartment only when added to intact acini. These findings suggest that PC-BSA may regulate EGF binding via a novel mechanism that is independent of protein kinase C activation or Ca2+ mobilization.

Differential binding and biological activities of epidermal growth factor and transforming growth factor alpha in a human pancreatic cancer cell line.

The binding characteristics and biological activities of epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha) were studied in T3M4 human pancreatic cancer cells. Scatchard analysis of 125I-EGF binding data at pH 7.4 indicated the presence of two orders of binding sites: a high-affinity site (Kd = 0.58 nM; 25,300 sites/cell) and a low-affinity site (Kd = 7.0 nM; 484,000 sites/cell). At pH 8.5, there was a decrease in the number of high-affinity sites. In contrast, only a single order of high-affinity sites was detected with 125I-TGF-alpha at either pH 7.4 (Kd = 0.57 nM; 100,200 sites/cell) or pH 8.5 (Kd = 0.70 nM; 230,400 sites/cell). The two ligands bound to the same receptor, as determined in cross-linking experiments and in competitive binding assays performed in the presence of an anti-EGF receptor antibody that allows for EGF binding. Phosphoamino acid analysis of the immunoprecipitated EGF receptor indicated that EGF exerted a greater effect than TGF-alpha on tyrosine phosphorylation of the receptor. EGF and TGF-alpha also exhibited different potencies with respect to their effects on inositol 1,4,5-trisphosphate generation and exerted divergent effects on the kinetics of inositol 1,4,5-trisphosphate formation. These findings point to dissimilar interactions of EGF and TGF-alpha with the EGF receptor in T3M4 cells, which may lead to differential activation of signal transduction pathways by these ligands.

Divergent effects of epidermal growth factor and transforming growth factors on a human endometrial carcinoma cell line.

Epidermal growth factor (EGF), at concentrations ranging from 0.83 to 4.98 nM, markedly inhibited the proliferation of RL95-2 cells that were seeded at low plating densities (4.7 X 10(3) cells/cm2). Under the same incubation conditions, 16.6 pM EGF enhanced cell proliferation. At high plating densities (2.5 X 10(4) cells/cm2) 0.83 nM EGF also stimulated cell proliferation. Both the inhibitory and stimulatory effects of EGF were mimicked by transforming growth factor-alpha (TGF-alpha). However, the inhibitory action of TGF-alpha was always greater that of EGF. Binding studies with 125I-labeled TGF-alpha indicated that maximal cell surface binding of TGF-alpha occurred at 15 min, whereas maximal internalization occurred at 45 min. Both cell surface and internalized radioactivity declined sharply thereafter. Analysis of radioactivity released into the incubation medium during pulse-chase experiments indicated that RL95-2 cells extensively degraded both TGF-alpha and EGF. The lysosomotropic compound methylamine arrested the generation of low-molecular-weight degradation products of EGF, but not of TGF-alpha. In contrast to EGF and TGF-alpha, transforming growth factor-beta (TGF-beta) inhibited the proliferation of RL95-2 cells that were seeded at either low or high plating densities. Further, transforming growth factor-beta induced the appearance of large cuboidal cells that were readily distinguished from cells treated with either EGF or TGF-alpha. These findings point to complex regulatory actions of growth factors on the proliferation of RL95-2 cells and suggest that the processing of TGF-alpha following EGF receptor activation is distinct from the processing of EGF.

Differential regulation of expression of three transforming growth factor beta species in human breast cancer cell lines by estradiol.

Transforming growth factor (TGF)-beta is a potent regulator of many cell functions and a growth inhibitor for mammary epithelial cells. We now know of three highly homologous members of the human TGF-beta gene family. We have studied the expression of TGF-beta 1, -beta 2, and -beta 3 mRNA in four human breast cancer cell lines. Using the RNase protection assay, we have detected mRNA expression of TGF-beta 1, -beta 2, and -beta 3 by T-47D cells, TGF-beta 1 and -beta 3 by ZR-75-1 cells, and TGF-beta 1 by MCF-7 cells. Treatment of these estrogen receptor-positive cells with 10 nM estradiol for 48 h resulted in decreased mRNA levels of TGF-beta 2 and -beta 3 but did not affect mRNA levels of TGF-beta 1. Expression of TGF-beta 1 and -beta 2 mRNA by an estrogen receptor-negative cell line, MDA-MB-231, was not changed by estradiol treatment. Treatment of cells with the antiestrogen tamoxifen (1 microM) did not significantly alter mRNA levels for any of the three TGF-beta species. We have further determined that estradiol treatment of T-47D was associated with diminished secretion of TGF-beta into the medium. Both TGF-beta 1 and -beta 2 inhibited the proliferation of MCF-7 cells, and neither protein affected the growth of T-47D cells. TGF-beta 1 was at least 10-fold more potent than TGF-beta 2 at inhibiting the growth of MCF-7 cells.

Coexpression of the c-met proto-oncogene and hepatocyte growth factor in human pancreatic cancer.

The c-met proto-oncogene encodes a transmembrane tyrosine kinase receptor (MET) that has the capacity to modulate cell proliferation and differentiation; it is activated by the hepatocyte growth factor. Using a highly specific anti-MET antibody we found mild MET immunoreactivity in acinar, ductal, and islet cells in the normal human pancreas and intense MET immunoreactivity in many of the duct-like cancer cells in 14 of 16 human pancreatic adenocarcinomas. Intense MET immunoreactivity was also evident in the ductal cells in regions adjacent to the cancer cells. Northern blot analysis of total RNA revealed that, by comparison with the normal pancreas, pancreatic cancers exhibited a 7-fold (P < 0.01) increase in c-met mRNA levels. Hepatocyte growth factor mRNA levels were increased 10-fold (P < 0.05) in the same cancers. The concomitant over-expression of c-met and hepatocyte growth factor in human pancreatic cancers suggests that there is excessive activation of c-met-dependent signaling pathways that may contribute to pancreatic cancer cell growth in vivo.

Aberrant expression of type I fibroblast growth factor receptor in human pancreatic adenocarcinomas.

Acidic and basic fibroblast growth factors are mitogenic polypeptides that are overexpressed in pancreatic cancer. To determine whether fibroblast growth factors may exert direct effects on pancreatic cancer cells in vivo, we compared the expression of the high-affinity type I fibroblast growth factor receptor (FGFR-1) in human pancreatic tissues. In the normal pancreas, FGFR-1 immunostaining was seen mainly in acinar cells. In pancreatic cancers, FGFR-1 was abundant in ductal-like cancer cells which also exhibited many FGFR-1 mRNA in situ hybridization grains. Analysis by the polymerase chain reaction and RNase protection revealed that the 2-immunoglobulin-like and the 3-immunoglobulin-like forms of FGFR-1 were expressed in all tissue samples, and that the 2-immunoglobulin-like form was overexpressed in the cancer tissues by comparison with the normal tissues. These findings suggest that the 2-immunoglobulin-like form of FGFR-1 may contribute to aberrant autocrine and paracrine pathways in pancreatic cancer.

Insulin-like growth factor I overexpression in human pancreatic cancer: evidence for autocrine and paracrine roles.

We assessed the potential roles of insulin-like growth factor-I (IGF-I) and the IGF-I receptor (IGF-IR) in human pancreatic cancer. IGF-I enhanced the growth of ASPC-1 and COLO-357 human pancreatic cancer cells, and this effect was significantly inhibited by a highly specific monoclonal anti-IGF-IR antibody (alpha IR3). Both cell lines expressed mRNA transcripts for IGF-IR, and basal cell growth was significantly reduced by an IGF-IR antisense oligodeoxynucleotide. IGF-I mRNA transcripts were not detected in either cell line or in two additional pancreatic cancer cell lines. In contrast, analysis of 12 pancreatic cancers revealed a 32-fold increase (P < 0.01) in IGF-I mRNA levels by comparison with the low levels observed in the normal pancreas. By in situ hybridization, IGF-I mRNA grains were present in both the cancer cells and in the surrounding connective tissue. Six of the cancers exhibited a 4.4-fold increase in IGF-IR mRNA levels. These findings suggest that IGF-I may participate in aberrant autocrine and paracrine activation of IGF-IR in pancreatic cancer in vivo.

Enhanced expression of the type II transforming growth factor beta receptor in human pancreatic cancer cells without alteration of type III receptor expression.

We have recently found that human pancreatic adenocarcinomas exhibit strong immunostaining for the three mammalian transforming growth factor beta (TGF-beta) isoforms. These important growth-regulating polypeptides bind to a number of proteins, including the type I TGF-beta receptor (T beta R-I), type II TGF-beta receptor (T beta R-II), and the type III TGF-beta receptor (T beta R-III). In the present study we sought to determine whether T beta R-II and T beta R-III expression is altered in pancreatic cancer. Northern blot analysis indicated that, by comparison with the normal pancreas, pancreatic adenocarcinomas exhibited a 4.6-fold increase (P < 0.01) in mRNA levels encoding T beta R-II. In contrast, mRNA levels encoding T beta R-III were not increased. In situ hybridization showed that T beta R-II mRNA was expressed in the majority of cancer cells, whereas mRNA grains encoding T beta R-III were detectable in only a few cancer cells and were present mainly in the surrounding stroma. These findings suggest that enhanced levels of T beta R-II may have a role in regulating human pancreatic cancer cell growth, while T beta R-III may function in the extracellular matrix.

KAI1 expression is up-regulated in early pancreatic cancer and decreased in the presence of metastases.

KAI1 is a metastasis suppressor gene for prostate cancer that is located on chromosome 11p11.2-13. Using Northern blot analysis and in situ hybridization, we studied expression of KAI1 mRNA in specimens from 14 normal pancreases and 27 primary pancreatic cancers, and then correlated the findings with the clinical and histopathological parameters of the patients. Northern blot analysis showed increased steady-state levels of KAI1 mRNA expression in 24 of 27 (89%) pancreatic cancer samples. In situ hybridization showed enhanced KAI1 mRNA levels in the pancreatic cancer cells in 82% cancer tissues. The stroma surrounding the cancer mass and normal pancreatic tissue adjacent to the cancer cells exhibited very low levels of KAI1 mRNA expression. Correlation of the mRNA levels obtained by Northern blot analysis with clinical parameters of the patients revealed that KAI1 mRNA levels were significantly higher (P < 0.01) in earlier tumor stages (I, II), compared with advanced tumor stages (III, IV) in which lymph node or distant metastases were present. Furthermore, poorly differentiated tumors had significantly higher KAI1 mRNA levels than those that were moderately or well differentiated (P < 0.05). No association between KAI1 expression and survival was found. Our results indicate that KAI1 mRNA expression is reduced in patients with advanced tumor stages. This suggests that reduction of KAI1 expression might enable pancreatic cancer cells to spread in lymph nodes and to distant organs.

Inhibition of cyclin D1 expression in human pancreatic cancer cells is associated with increased chemosensitivity and decreased expression of multiple chemoresistance genes.

Cyclin D1 belongs to a family of protein kinases that have been implicated in cell cycle regulation. Inhibition of cyclin D1 expression has been recently shown (M. Kornmann, et al., J. Clin. Invest, 101: 344-352, 1998) to suppress pancreatic cancer cell growth and increase cytotoxic actions of cisplatinum. The aim of the present study was to determine whether inhibition of cyclin D1 expression also modulates the effects of other antineoplastic drugs and whether it is associated with alterations in the level of expression of drug resistance genes. The suppression of cyclin D1 expression after the stable transfection of a cyclin D1 antisense construct in PANC-1 and COLO-357 human pancreatic cancer cells resulted in a significant increase in sensitivity to the fluoropyrimidines 5-fluorouracil and 5-fluoro-2'-deoxyuridine and to mitoxantrone. All of the antisense-expressing dones exhibited a decrease in thymidylate synthase and an increase in thymidine phosphorylase mRNA expression as determined by reverse transcription-PCR analysis and decreased levels of MDR-1 and MRP mRNA as determined by Northern blotting. These findings demonstrate that the inhibition of cyclin D1, in addition to suppressing the growth of pancreatic cancer cells, enhances their responsiveness to multiple chemotherapeutic agents and suggest that this effect may be due to the altered expression of several chemoresistance genes.

Enhanced expression of the insulin receptor substrate-2 docking protein in human pancreatic cancer.

Insulin receptor substrate-2 (IRS-2) is a multisite docking protein implicated in mitogenic signaling after activation of the insulin and insulin-like growth factor (IGF)-I receptors. In the present study, we characterized IRS-2 expression and function in human pancreatic cancer. IRS-2 mRNA and protein were expressed in ASPC-1 and COLO-357 human pancreatic cancer cell lines. Insulin, IGF-I, and IGF-II enhanced the growth of both cell lines, stimulated tyrosine phosphorylation of IRS-2, and increased IRS-2-associated phosphatidylinositol (PI) 3-kinase activity. The mitogenic effects of insulin, IGF-I, and IGF-II were markedly attenuated by the PI 3-kinase inhibitor LY 294002. Northern blot analysis of total RNA extracted from normal and cancerous tissues revealed that IRS-2 mRNA levels were increased in the cancer tissues (P = 0.032). In the normal pancreas, IRS-2 immunoreactivity was present at low levels in some ductal and acinar cells and at moderate levels in a heterogeneous pattern in all of the endocrine islets. In the pancreatic cancers, IRS-2 was abundant in the ductal-like cancer cells. These findings indicate that IRS-2 is overexpressed in human pancreatic cancer and suggest that it may contribute to enhanced mitogenic signaling via the PI 3-kinase pathway, thereby leading to excessive growth stimulation in this malignancy.