Cyclin-dependent kinase 4 upregulation mediates acquired resistance of dabrafenib plus trametinib in BRAF V600E-mutated lung cancer.

BACKGROUND: Combination therapy with the B-Raf inhibitor, dabrafenib, and the MEK inhibitor, trametinib (DT) is commonly used to treat patients with B-Raf proto-oncogene, serine/threonine kinase V600E (BRAF V600E)-mutated non-small cell lung cancer (NSCLC). However, the mechanisms through which cancer develops DT resistance are unclear. Here, we investigated new mechanisms underlying acquired DT-resistant NSCLC with the BRAF V600E mutation. METHODS: We compared genomic signatures before and after DT treatment in patients with NSCLC. RESULTS: Two of four patients treated with DT developed carcinomatous pleuritis within 3 months. Target DNA sequencing and quantitative polymerase chain reaction (PCR) analyses revealed the increased expression level of cyclin-dependent kinase 4 (CDK4). We also found prominent protein expression of CDK4 after DT treatment. Induction of CDK4 expression in a cell line derived from a patient with the BRAF V600E mutation resulted in partial resistance to dabrafenib. CONCLUSIONS: Our findings suggest a possible relationship between CDK4 upregulation and acquired resistance to DT therapy.

Resection for pancreatic cancer metastases contributes to survival: A case report with sequential tumor genotype profiling during the long-term postoperative course.

INTRODUCTION: Surgical management is not a standard treatment option for metastatic recurrence of pancreatic adenocarcinoma. However, the surgical management of a solitary metastasis is useful in selected cases. PATIENT CONCERNS: A 42-year-old woman was referred to our hospital on account of epigastric pain associated with a mass in the pancreatic body. The patient had a family history of branch duct-type intraductal papillary mucinous neoplasm of the pancreas. DIAGNOSIS: The patient was diagnosed with pancreatic ductal adenocarcinoma (PDA) complicated with pancreatitis due to pancreatic duct involvement. INTERVENTIONS: The patient underwent distal pancreatectomy, and pathological examination revealed a tubular adenocarcinoma. Solitary liver and lung metastatic tumors were found 6 and 43 months after the initial presentation, respectively, and sequential metastasectomies were performed. OUTCOMES: The patient survived until 8 years after her initial presentation. The genetic profiles of the resected specimens, primary PDA, and recurrent tumors in the liver and lung possessed identical KRAS mutations at codon 12, whereas there were no mutations in the main tumor suppressor genes, such as TP53, CDKN2A, and SMAD4. Multiplex polymerase chain reaction-based microsatellite instability assay demonstrated microsatellite stability. CONCLUSION: In our case, the patient with pancreatic adenocarcinoma survived for over 8 years following the resection of the primary tumor and resections of metachronous metastatic tumors. The outcome of PDA may be associated with the genetic profile that regulates its biological behavior. Operative management of solitary metastatic tumors may be a therapeutic options for selected patients with pancreatic cancer.

Tracking the Clonal Evolution of Adenosquamous Carcinoma, a Rare Variant of Intraductal Papillary Mucinous Neoplasm of the Pancreas.

Adenosquamous carcinoma (ASC) is an uncommon variant of pancreatic neoplasm. We sought to trace the mode of tumor progression using specimens of ASC associated with intraductal papillary mucinous neoplasm (IPMN) of the pancreas. A resected specimen of the primary pancreatic ASC, developed in a 72-year-old man, was subjected to mutation profiling using amplicon-targeted sequencing and digital polymerase chain reaction. DNA was isolated from each histological compartment including noninvasive IPMN, squamous cell carcinoma (SCC), and adenocarcinoma (AC). Histologically, an IPMN with a large mural nodule was identified. The invasive tumor predominantly consisted of SCC, and a smaller AC was found around the lesion. Squamous metaplasias were sporadically distributed within benign IPMNs. Mutation alleles KRAS and GNAS were identified in all specimens of IPMN including the areas of squamous metaplasia. In addition, these mutations were found in SCC and AC. Clear transition from flat/low-papillary IPMN to SCC indicated a potent invasion front, and the SCC compartment was genetically unique, because the area has a higher frequency of mutation KRAS. The invasive tumors with distinct histological appearances shared the form of noninvasive IPMN as a common precursor, rather than de novo cancer, suggesting the significance of a genetic profiling scheme of tumors associated with IPMN.

Metachronous pancreatic cancer originating from disseminated founder pancreatic intraductal neoplasias (PanINs).

Clonal populations originated from benign-looking 'founder cells' may spread widely within pancreas instead of being localized in situ before frank pancreatic ductal adenocarcinoma (PDA) can be detected. Metachronous PDA is not common event, and we here sought to define potent origin of multiple PDAs developed in a woman using advanced genetics technologies. Curative resection of pancreatic head tumour was performed; however, 'recurrent' lesions in the remnant pancreas were found 3.5 years later and total pancreatectomy was subsequently performed. The metachronous lesions were morphologically similar to the primary PDA. Using a next-generation sequencing and digital PCR, all three PDAs were shown to possess rare somatic mutations in KRAS (p.T58I & p.Q61H). Curiously, identical KRAS mutations were found in low-grade 'intraepithelial' lesions, which localized in normal area of the pancreas and one of them possessed p53 mutation, which was also found in the PDAs. The footprint of the tumour evolution marked by mutational profiling supports a human correlate to the mouse models of 'dissemination' occurring at the earliest stages of pancreatic neoplasia.

Haplotype analysis of the human collectin placenta 1 (hCL-P1) gene.

Collectins are a family of C-type lectins found in vertebrates. These proteins have four regions, a relatively short N-terminal region, a collagen-like region, an alpha-helical coiled coil, and a carbohydrate recognition domain. Collectins are involved in host defense through their ability to bind carbohydrate antigens on microorganisms. Type A scavenger receptors are classical-type scavenger receptors that also have collagen-like domains. We previously described a new scavenger receptor, collectin from placenta [collectin placenta 1 (CL-P1)]. CL-P1 is a type II membrane protein with all four regions. We found that CL-P1 can bind and phagocytize both bacteria and yeast. In addition to that, it reacts with oxidized low-density lipoprotein (LDL) but not with acetylated LDL. These results suggest that CL-P1 might play important roles in host defenses and/or atherosclerosis formation. One rational strategy to study the role of CL-P1 in these pathological conditions would be to perform a haplotype association study using human samples. As a first step for this strategy, we analyzed the haplotype structure of the CL-P1gene. By sequencing the CL-P1 gene in ten Japanese volunteers, we identified five single-nucleotide polymorphisms (SNPs) with a minor allele frequency of at least 29%. To obtain SNPs in the 5'-upstream region of the gene, we screened a total of 20 SNPs described in the database and finally picked up one SNP for the present study. Thus, a total of six SNPs, one in the 5'-upstream region, two in intron 2, one in exon 5, and two in exon 6, were used to analyze the haplotype structure of the gene, with DNAs derived from 54 individuals (108 alleles). The analysis revealed that only two of six SNPs showed significant linkage disequilibrium ( r(2) > 0.5) with each other. This haplotype information may be useful in disease-association studies in which a contribution of the CL-P1 gene has been suspected, especially in immunological disturbance or atherosclerosis. Two SNPs in exon 6, both leading to amino acid substitutions, could be candidates for influencing disease susceptibility.