Calcitonin promotes in vivo metastasis of prostate cancer cells by altering cell signaling, adhesion, and inflammatory pathways

Abstract

Expression of calcitonin (CT) and its receptor (CTR) is elevated in advanced prostate cancer (PC).Although the significance of CT-CTR axis in PC cell growth, invasion, and epithelial to mesenchymal transition has been established, its role in tumor metastasis has not been examined. To examine the role of CT-CTR axis in tumor metastasis, we employed stable CT-CTR activated and silenced system of three PC cell lines, LNCaP cells that lack endogenous CT, PC-3 cells that lack endogenous CTR, and PC-3M cells that co-express CT and CTR. Enforced expression of CT in LNCaP cells and CTR in PC-3 cells increased their ability to form orthotopic tumors and distant metastases in multiple organs. By contrast, silencing of CT expression in PC-3M cells not only reduced their tumorigenicity, but also completely abrogated their metastatic potential. To investigate the effect of in vivo silencing of CT expression on tumor growth, we employed recombinant adeno-associated virus (rAAV) to deliver anti-CT ribozymes in preexisting tumors of nude mice and large probasin promoter (LPB)-Tag transgenic mice. rAAV-CT K treatment not only abrogated the growth of pre-implanted tumors in nude mice, but also significantly reduced the growth of spontaneous tumors in LPB-Tag mice. Analysis of CT upregulated and silenced PC-3M transcriptomes revealed 105 genes affected by the modulation of CT expression. These CT signature genes generated survival, adhesion, pro-inflammatory, and pro-metastatic pathways. Added together, these data indicate a pivotal role for CT-CTR axis in PC metastasis and may serve as a potential therapeutic target for advanced PC.

Neuroendocrine prostate cancer (NEPCa) increased the neighboring PCa chemoresistance via altering the PTHrP/p38/Hsp27/androgen receptor (AR)/p21 signals

“…Early studies suggested that NEPCa might secrete different kinds of cytokines and peptides, including bombesin, calcitonin, parathyroid hormone-related protein (PTHrP), serotonin and VEGF, to stimulate progression in its neighboring PCa (9–11, 31, 32). We first compared the expression of some cytokines and peptides related to p38/MAPK signals between LNCaP and NE1.3 cells (33–37).…”

“…The significance of NEPCa has been regarded as not only a sign for PCa progression, but also an inducer of growth and survival for the neighboring PCa by secreting a variety of cytokines and peptides (9–11, 31, 32). For example, NEPCa secrete several neuropeptides, including bombesin, which can act as a mitogen in PCa tumors via activation of the transcription factor Elk-1 and the immediate early gene c-fos (46).…”

A-kinase anchoring protein 2 is required for calcitonin-mediated invasion of cancer cells

“…The SOI was performed under Ketamin/Xylazine anesthesia as previously described (Chien, et al 1999; Shah, et al 2009b; Shah, et al 2008). In brief, tumor cell suspensions (1×10 6 cells/20μl) were injected into the dorsal prostate, the mice were maintained on the laboratory diet ad libitum for up to sixty days, and were regularly monitored for tumor growth/metastasis with fluorography using Kodak 4000 MM imaging station (Thomas et al 2006).…”

Adeno-associated virus (AAV) vectors in cancer gene therapy

“…These include AAV2-maspin to LNCaP and DU145 prostate cancer tumors [144]; AAV2-nm23H1 to SW626-M4 metastatic ovarian cancer tumors [145]; AAV2-HGFK1 (kringle 1 domain of human hepatocyte growth factor) to CT26 and Lovo colorectal carcinoma tumors [146]; AAV2-encoded anti-calcitonin ribozymes to an orthotopic implantation model and a transgenic model of prostate cancer [147]; AAV2-4EBP1 (eukaryotic translation initiation factor 4E-binding protein 1) to a K-ras LA1 lung cancer model [148]; AAV2-mediated delivery of the chemokine receptor CXC chemokine receptor 2 (CXCR2) C-tail sequence to an HPAC pancreatic tumor model [149]; AAV1 delivery of IL-24 and apoptotin to a HepG2 liver cancer model [150]; AAV2-TAP (alpha-tocopherol-associated protein) to PC-3 and LNCaP prostate cancer tumors [151]; delivery of trichosanthin, packaged in AAV3-S663V+T492V vectors, to HuH7 hepatocellular carcinoma (HCC) tumors [66]; AAV2-decorin to a U87MG glioblastoma multiforme model [152]; AAV2-cathelicidin to HT-29 colon cancer tumors [153]; AAV8-mediated delivery of Niemann-Pick type C2 (NPC2) to the N-methyltransferase knockout (Gnmt−/−) transgenic spontaneous HCC model [154]; and AAV9-mediated delivery of human Mullerian inhibiting substance (MIS, albumin leader Q425R MIS (LRMIS)) in a xenograft model of ovarian cancer [155]. Additionally, groups have delivered the p53 tumor suppressor gene, commonly mutated in cancerous cells, using AAV2 vectors to bladder cancer cells [156] and non-small cell lung cancer cells [157] in vitro and to an H358 bronchioalveolar carcinoma tumor model in vivo [158].…”