Project description:Genomic and epigenomic studies support that adenocarcinomas of the gallbladder develop according to a metaplasia-biliary intraepithelial neoplasia (BilIN)-adenocarcinoma histogenic sequence, in which metaplasia and BilIN are non-cancerous lesions of the epithelium. Moreover, recent genomic data suggest that adenocarcinoma can develop in a BilIN-dependent or -independent way, pointing toward patient-specific tumourigenic processes. Spatial transcriptomic data addressing these processes are still missing. Here, using GeoMx digital spatial profiling (NanoString), we characterized the spatial transcriptome of normal gallbladder epithelium, BilINs and adenocarcinoma coexisting within the same samples. To address intra-patient variability we profiled the whole transcriptome of a high number of regions of interest (ROIs) per sample in two patients (Patient #1, 81 year old woman: 24 ROIs; Patient #2, 53-year old man:32 ROIs), with each ROI covering approximately 200 cells of normal epithelium, low-grade BilIN, high-grade BilIN or adenocarcinoma. Our results showed that each type of lesion displayed little transcriptomic variability within the same patient, but differed significantly between patients. They also suggested that adenocarcinoma can derive from high-grade BilIN or from low-grade BilIN, with co-existing high-grade BilIN evolving via a distinct process in the latter case. We also provide strong evidence for patient-specific tumourigenic mechanisms, characterized by distinct sequences of signalling pathway activation. Among those pathways, we functionally investigated SEMAPHORIN 4A (SEMA4A) and provided evidence that repression of SEMA4A expression, as is observed in the gallbladder samples of the two patients, can enhance cell migration and survival, and perturb polarisation of the epithelial cells. In conclusion, our results support that gallbladder adenocarcinoma develops according to patient-specific processes that can be promoted by repression of SEMA4A. They underscore the need to gain gene expression data in addition to histological information to evaluate the risk of low-grade preneoplastic lesions.

Project description:Background: With less than a 5% survival rate pancreatic adenocarcinoma (PDAC) is almost uniformly lethal. In order to make a significant impact on survival of patients with this malignancy, it is necessary to diagnose the disease early, when curative surgery is still possible. Detailed knowledge of the natural history of the disease and molecular events leading to its progression is therefore critical. Methods and Findings: We have analysed the precursor lesions, PanINs, from prophylactic pancreatectomy specimens of patients from four different kindreds with high risk of familial pancreatic cancer who were treated for histologically proven PanIN-2/3. Thus, the material was procured before pancreatic cancer has developed, rather than from PanINs in a tissue field that already contains cancer. Genome-wide transcriptional profiling using such unique specimens was performed. Bulk frozen sections displaying the most extensive but not microdissected PanIN-2/3 lesions were used in order to obtain the holistic view of both the precursor lesions and their microenvironment. A panel of 76 commonly dysregulated genes that underlie neoplastic progression from normal pancreas to PanINs and PDAC were identified. In addition to shared genes some differences between the PanINs of individual families as well as between the PanINs and PDACs were also seen. This was particularly pronounced in the stromal and immune responses. Conclusions: Our comprehensive analysis of precursor lesions without the invasive component provides the definitive molecular proof that PanIN lesions beget cancer from a molecular standpoint. We demonstrate the need for accumulation of transcriptomic changes during the progression of PanIN to PDAC, both in the epithelium and in the surrounding stroma. An identified 76-gene signature of PDAC progression presents a rich candidate pool for the development of early diagnostic and/or surveillance markers as well as potential novel preventive/therapeutic targets for both familial and sporadic pancreatic adenocarcinoma. Gene expression of 13 PanIN samples was compared to profiling data of whole biopsies from normal donor pancreas (N1 to 4, two replicated samples) and sporadic PDAC (PDAC1 to 6).Ttwo PDAC samples (PDAC 3 and 4) and a replicate of one normal specimen (N4) were removed during the hybridisation quality assessment.

Project description:Background: With less than a 5% survival rate pancreatic adenocarcinoma (PDAC) is almost uniformly lethal. In order to make a significant impact on survival of patients with this malignancy, it is necessary to diagnose the disease early, when curative surgery is still possible. Detailed knowledge of the natural history of the disease and molecular events leading to its progression is therefore critical. Methods and Findings: We have analysed the precursor lesions, PanINs, from prophylactic pancreatectomy specimens of patients from four different kindreds with high risk of familial pancreatic cancer who were treated for histologically proven PanIN-2/3. Thus, the material was procured before pancreatic cancer has developed, rather than from PanINs in a tissue field that already contains cancer. Genome-wide transcriptional profiling using such unique specimens was performed. Bulk frozen sections displaying the most extensive but not microdissected PanIN-2/3 lesions were used in order to obtain the holistic view of both the precursor lesions and their microenvironment. A panel of 76 commonly dysregulated genes that underlie neoplastic progression from normal pancreas to PanINs and PDAC were identified. In addition to shared genes some differences between the PanINs of individual families as well as between the PanINs and PDACs were also seen. This was particularly pronounced in the stromal and immune responses. Conclusions: Our comprehensive analysis of precursor lesions without the invasive component provides the definitive molecular proof that PanIN lesions beget cancer from a molecular standpoint. We demonstrate the need for accumulation of transcriptomic changes during the progression of PanIN to PDAC, both in the epithelium and in the surrounding stroma. An identified 76-gene signature of PDAC progression presents a rich candidate pool for the development of early diagnostic and/or surveillance markers as well as potential novel preventive/therapeutic targets for both familial and sporadic pancreatic adenocarcinoma.

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Spatial transcriptomic profiling of precursor lesions of gallbladder adenocarcinoma

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