Profiling of cMET and HER Family Receptor Expression in Pancreatic Ductal Adenocarcinomas and Corresponding Lymph Node Metastasis to Assess Relevant Pathways for Targeted Therapies: Looking at the Soil Before Planting the Seed

c-Met-targeted near-infrared fluorescent probe for real-time depiction and dissection of perineural invasion and lymph node metastasis lesions in pancreatic ductal adenocarcinoma xenograft models

Pancreatic ductal adenocarcinoma (PDAC), a fatal malignant tumour, has a high postoperative recurrence rate, mainly due to the difficulty of discerning occult lesions, including those related to perineural invasion (PNI) and lymph node metastasis (LNM). Cellular mesenchymal-epithelial transition factor (c-Met), an excellent imaging marker, is aberrantly expressed in the majority of PDACs. Thus, we plan to utilize a c-Met-targeted near-infrared fluorescent (NIRF) probe for real-time visualization and dissection of PDAC, and corresponding PNI and LNM lesions. Immunohistochemistry showed c-Met expression in PDAC, PNI and LNM reached 94.3% (100/106), 88.3% (53/60), and 71.4% (25/35), respectively, and its expression in PNI and LNM was significantly correlated with that in primary PDAC (r = 0.66, p < 0.0001 and r = 0.44, p < 0.01, respectively). SHRmAb-IR800 was successfully synthesized using an anti-c-Met antibody and a NIRF dye. The in vitro targeting ability of SHRmAb-IR800 was higher in CFPAC1 cells (c-Met positive) than in Miapaca-2 cells (c-Met negative) (p < 0.05). In vivo NIRF imaging of CFPAC1 subcutaneous tumours demonstrated higher accumulation of SHRmAb-IR800 than the control probe (p < 0.05). The signal-to-background ratio (TBR) of an orthotopic PDAC tumour was 3.38 ± 0.46, and imaging with SHRmAb-IR800 facilitated the resection of metastatic lesions with sensitivity and specificity values of 93.3% (56/60) and 87.1% (27/31), respectively. Furthermore, tiny PNI and LNM lesions in xenograft models were detected by NIRF imaging, with TBRs measuring 2.59 ± 0.19 and 2.88 ± 0.72, respectively. Therefore, the clinical translation of this probe might shed new light on NIRF-guided pancreatectomy and improve the surgical prognosis of PDAC patients.

Circular RNA ciRS-7 promotes the proliferation and metastasis of pancreatic cancer by regulating miR-7-mediated EGFR/STAT3 signaling pathway

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is the most deadly type of tumor, and its pathogenesis remains unknown. Circular RNAs (circRNAs) may be functional and bind to microRNAs and consequently, influence the activity of targeted mRNAs. Recent researches indicate that one circRNA, ciRS-7, acts as a sponge of miR-7 and thus, inhibits its activity. It is well known that miR-7 is a cancer suppressor in many cancers. However, the relationship between ciRS-7 and miR-7, and the role of ciRS-7 in PDAC, remains to be elucidated.

METHODS

miR-7 and ciRS-7 expression in 41 pairs of PDAC tumors and their paracancerous tissues were detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The relationships between their expression levels and clinicopathological features in PDAC tissues were assessed. The relationship between miR-7 and ciRS-7 was also assessed by Spearman's correlation. We also used cell lines to evaluate the role of ciRS-7 in cell line behavior. The ciRS-7 interfere RNA (siRNA) and its empty vector were transfected into PDAC cells. PDAC cells proliferation and invasion abilities were detected by MTT assay and invasion analysis. The expression of proteins was assessed by Western blotting.

RESULTS

ciRS-7 expression was significantly higher in PDAC tissues than paracancerous tissues (P = 0.002). However, miR-7 expression showed the opposite trend (P = 0.048). Moreover, ciRS-7 expression was inversely correlated with miR-7 in PDAC (r_s = -0.353, P = 0.023). ciRS-7 expression was also significantly elevated in venous invasion (3.72 ± 2.93 vs. 2.14 ± 1.26; P = 0.028) and lymph node metastasis (4.19 ± 2.75 vs. 2.32 ± 1.90; P = 0.016) in PDAC patients. Furthermore, ciRS-7 knockdown suppressed cell proliferation and invasion of PDAC cells (P < 0.05), and the downregulation of ciRS-7 resulted in miR-7 overexpression and subsequent inhibition of epidermal growth factor receptor (EGFR) and signal transducer and activator of transcription 3 (STAT3).

CONCLUSIONS

Circular RNA ciRS-7 plays an oncogene role in PDAC, partly by targeting miR-7 and regulating the EGFR/STAT3 signaling pathway.

CASTIN: a system for comprehensive analysis of cancer-stromal interactome

BACKGROUND

Cancer microenvironment plays a vital role in cancer development and progression, and cancer-stromal interactions have been recognized as important targets for cancer therapy. However, identifying relevant and druggable cancer-stromal interactions is challenging due to the lack of quantitative methods to analyze whole cancer-stromal interactome.

RESULTS

We present CASTIN (CAncer-STromal INteractome analysis), a novel framework for the evaluation of cancer-stromal interactome from RNA-Seq data using cancer xenograft models. For each ligand-receptor interaction which is derived from curated protein-protein interaction database, CASTIN summarizes gene expression profiles of cancer and stroma into three evaluation indices. These indices provide quantitative evaluation and comprehensive visualization of interactome, and thus enable to identify critical cancer-microenvironment interactions, which would be potential drug targets. We applied CASTIN to the dataset of pancreas ductal adenocarcinoma, and successfully characterized the individual cancer in terms of cancer-stromal relationships, and identified both well-known and less-characterized druggable interactions.

CONCLUSIONS

CASTIN provides comprehensive view of cancer-stromal interactome and is useful to identify critical interactions which may serve as potential drug targets in cancer-microenvironment. CASTIN is available at: http://github.com/tmd-gpat/CASTIN .