Biological significance of KRAS mutant allele expression in ovarian endometriosis

Cancer science

2021 May 01

Yachida, N;Yoshihara, K;Suda, K;Nakaoka, H;Ueda, H;Sugino, K;Yamaguchi, M;Mori, Y;Yamawaki, K;Tamura, R;Ishiguro, T;Kase, H;Motoyama, T;Enomoto, T;
PMID: 33675098 | DOI: 10.1111/cas.14871

KRAS is the most frequently mutated in ovarian endometriosis. However, it is unclear whether the KRAS mutant allele's mRNA is expressed and plays a biological role in ovarian endometriosis. Here, we performed mutation-specific RNA in situ hybridization to evaluate mutant allele expression of KRAS p.G12V, the most frequently detected mutation in ovarian endometriosis in our previous study, in formalin-fixed paraffin-embedded tissue (FFPE) samples of ovarian endometriosis, cancer cell lines, and ovarian cancers. First, we verified that mutant or wild-type allele of KRAS were expressed in all 5 cancer cell lines and 9 ovarian cancer cases corresponding to the mutation status. Next, we applied this assay to 26 ovarian endometriosis cases, and observed mutant allele expression of KRAS p.G12V in 10 cases. Mutant or wild-type allele of KRAS were expressed in line with mutation status in 12 available endometriosis cases for which KRAS gene sequence was determined. Comparison of clinical features between ovarian endometriosis with KRAS p.G12V mutant allele expression and with KRAS wild-type showed that KRAS p.G12V mutant allele expression was significantly associated with inflammation in ovarian endometriosis. Finally, we assessed the spatial distribution of KRAS mutant allele expression in 5 endometriosis cases by performing multiregional sampling. Intratumor heterogeneity of KRAS mutant allele expression was observed in two endometriosis cases, whereas the spatial distribution of KRAS p.G12V mutation signals were diffuse and homogenous in ovarian cancer. In conclusion, evaluation of oncogene mutant expression will be useful for clarifying the biological significance of oncogene mutations in benign tumors.

Defining the spatial landscape of KRAS mutated congenital pulmonary airway malformations: a distinct entity with a spectrum of histopathologic features

Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc

2022 Jul 06

Nelson, ND;Xu, F;Chandrasekaran, P;Litzky, LA;Peranteau, WH;Frank, DB;Li, M;Pogoriler, J;
PMID: 35794233 | DOI: 10.1038/s41379-022-01129-0

The potential pathogenetic mechanisms underlying the varied morphology of congenital pulmonary airway malformations (CPAMs) have not been molecularly determined, but a subset have been shown to contain clusters of mucinous cells (MCC). These clusters are believed to serve as precursors for potential invasive mucinous adenocarcinoma, and they are associated with KRAS codon 12 mutations. To assess the universality of KRAS mutations in MCCs, we sequenced exon 2 of KRAS in 61 MCCs from 18 patients, and we found a KRAS codon 12 mutation in all 61 MCCs. Furthermore, all MCCs from a single patient always had the same KRAS mutation, and the same KRAS mutation was also found in non-mucinous lesional tissue. Next generation sequencing of seven MCCs showed no other mutations or copy number variations. Sequencing of 46 additional CPAMs with MCCs revealed KRAS mutations in non-mucinous lesional tissue in all cases. RNA in situ hybridization confirmed widespread distribution of cells with mutant KRAS RNA, even extending outside of the bronchiolar type epithelium. We identified 25 additional CPAMs with overall histologic architecture similar to CPAMs with KRAS mutations but without identifiable MCCs, and we found KRAS mutations in 17 (68%). The histologic features of these KRAS mutated CPAMs included type 1 and type 3 morphology, as well as lesions with an intermediate histologic appearance, and analysis revealed a strong correlation between the specific amino acid substitution and histomorphology. These findings, together with previously published model organism data, suggests that the formation of type 1 and 3 CPAMs is driven by mosaic KRAS mutations arising in the lung epithelium early in development and places them within the growing field of mosaic RASopathies. The presence of widespread epithelial mutation explains late metastatic disease in incompletely resected patients and reinforces the recommendation for complete resection of these lesions.

TGFβ pathway limits dedifferentiation following WNT and MAPK pathway activation to suppress intestinal tumourigenesis

Cell Death Differ.

2017 Jun 16

Cammareri P, Vincent DF, Hodder MC, Ridgway RA, Murgia C, Nobis M, Campbell AD, Varga J, Huels DJ, Subramani C, Prescott KLH, Nixon C, Hedley A, Barry ST, Greten FR, Inman GJ, Sansom OJ.
PMID: 28622298 | DOI: 10.1038/cdd.2017.92

Recent studies have suggested increased plasticity of differentiated cells within the intestine to act both as intestinal stem cells (ISCs) and tumour-initiating cells. However, little is known of the processes that regulate this plasticity. Our previous work has shown that activating mutations of Kras or the NF-κB pathway can drive dedifferentiation of intestinal cells lacking Apc. To investigate this process further, we profiled both cells undergoing dedifferentiation in vitro and tumours generated from these cells in vivo by gene expression analysis. Remarkably, no clear differences were observed in the tumours; however, during dedifferentiation in vitro we found a marked upregulation of TGFβ signalling, a pathway commonly mutated in colorectal cancer (CRC). Genetic inactivation of TGFβ type 1 receptor (Tgfbr1/Alk5) enhanced the ability of KrasG12D/+ mutation to drive dedifferentiation and markedly accelerated tumourigenesis. Mechanistically this is associated with a marked activation of MAPK signalling. Tumourigenesis from differentiated compartments is potently inhibited by MEK inhibition. Taken together, we show that tumours arising in differentiated compartments will be exposed to different suppressive signals, for example, TGFβ and blockade of these makes tumourigenesis more efficient from this compartment.

Activating mutations in the MAP-kinase pathway define non-ossifying fibroma of bone.

J Pathol. 2018 Dec 13.

2018 Dec 13

Baumhoer D, Kovac M, Sperveslage J, Ameline B, Strobl AC, Krause A, Trautmann M, Wardelmann E, Nathrath M, Höller S, Hardes J, Gosheger G, Krieg AH, Vieth V, Tirabosco R, Amary F, Flanagan AM, Hartmann W.
PMID: 30549028 | DOI: 10.1002/path.5216

Non-ossifying fibroma, which occasionally results in pathologic fracture, is considered the most common benign and self-limiting lesion of the growing skeleton. By DNA sequencing we have identified hotspot KRAS, FGFR1 and NF1 mutations in 48 of 59 patients (81.4%) with NOF, at allele frequencies ranging from 0.04 to 0.61. Our findings define NOF as a genetically driven neoplasm caused in most cases by activated MAP-kinase signalling. Interestingly, this driving force either diminishes over time or at least is not sufficient to prevent autonomous regression and resolution. Beyond its contribution to a better understanding of the molecular pathogenesis of non-ossifying fibroma, this study adds another benign lesion to the spectrum of KRAS- and MAP-kinase signalling-driven tumours.

Systematic mapping of nuclear domain-associated transcripts reveals speckles and lamina as hubs of functionally distinct retained introns

Molecular cell

2022 Feb 09

Barutcu, AR;Wu, M;Braunschweig, U;Dyakov, BJA;Luo, Z;Turner, KM;Durbic, T;Lin, ZY;Weatheritt, RJ;Maass, PG;Gingras, AC;Blencowe, BJ;
PMID: 35182477 | DOI: 10.1016/j.molcel.2021.12.010

The nucleus is highly compartmentalized through the formation of distinct classes of membraneless domains. However, the composition and function of many of these structures are not well understood. Using APEX2-mediated proximity labeling and RNA sequencing, we surveyed human transcripts associated with nuclear speckles, several additional domains, and the lamina. Remarkably, speckles and lamina are associated with distinct classes of retained introns enriched in genes that function in RNA processing, translation, and the cell cycle, among other processes. In contrast to the lamina-proximal introns, retained introns associated with speckles are relatively short, GC-rich, and enriched for functional sites of RNA-binding proteins that are concentrated in these domains. They are also highly differentially regulated across diverse cellular contexts, including the cell cycle. Thus, our study provides a resource of nuclear domain-associated transcripts and further reveals speckles and lamina as hubs of distinct populations of retained introns linked to gene regulation and cell cycle progression.

	Description
sense Example: Hs-LAG3-sense	Standard probes for RNA detection are in antisense. Sense probe is reverse complent to the corresponding antisense probe.
Intron# Example: Mm-Htt-intron2	Probe targets the indicated intron in the target gene, commonly used for pre-mRNA detection
Pool/Pan Example: Hs-CD3-pool (Hs-CD3D, Hs-CD3E, Hs-CD3G)	A mixture of multiple probe sets targeting multiple genes or transcripts
No-XSp Example: Hs-PDGFB-No-XMm	Does not cross detect with the species (Sp)
XSp Example: Rn-Pde9a-XMm	designed to cross detect with the species (Sp)
O# Example: Mm-Islr-O1	Alternative design targeting different regions of the same transcript or isoforms
CDS Example: Hs-SLC31A-CDS	Probe targets the protein-coding sequence only
EnEm	Probe targets exons n and m
En-Em	Probe targets region from exon n to exon m
Retired Nomenclature
tvn Example: Hs-LEPR-tv1	Designed to target transcript variant n
ORF Example: Hs-ACVRL1-ORF	Probe targets open reading frame
UTR Example: Hs-HTT-UTR-C3	Probe targets the untranslated region (non-protein-coding region) only
5UTR Example: Hs-GNRHR-5UTR	Probe targets the 5' untranslated region only
3UTR Example: Rn-Npy1r-3UTR	Probe targets the 3' untranslated region only
Pan Example: Pool	A mixture of multiple probe sets targeting multiple genes or transcripts

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Advanced Cell Diagnostics

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