Mammalian tumor-like organs. 1. The role of tumor-like normal organs and atypical tumor organs in the evolution of development (carcino-evo-devo)

Background Earlier I hypothesized that hereditary tumors might participate in the evolution of multicellular organisms. I formulated the hypothesis of evolution by tumor neofunctionalization, which suggested that the evolutionary role of hereditary tumors might consist in supplying evolving multicellular organisms with extra cell masses for the expression of evolutionarily novel genes and the origin of new cell types, tissues, and organs. A new theory—the carcino-evo-devo theory—has been developed based on this hypothesis. Main text My lab has confirmed several non-trivial predictions of this theory. Another non-trivial prediction is that evolutionarily new organs if they originated from hereditary tumors or tumor-like structures, should recapitulate some tumor features in their development. This paper reviews the tumor-like features of evolutionarily novel organs. It turns out that evolutionarily new organs such as the eutherian placenta, mammary gland, prostate, the infantile human brain, and hoods of goldfishes indeed have many features of tumors. I suggested calling normal organs, which have many tumor features, the tumor-like organs. Conclusion Tumor-like organs might originate from hereditary atypical tumor organs and represent the part of carcino-evo-devo relationships, i.e., coevolution of normal and neoplastic development. During subsequent evolution, tumor-like organs may lose the features of tumors and the high incidence of cancer and become normal organs without (or with almost no) tumor features.

Homologous Recombination Deficiencies and Hereditary Tumors

Homologous recombination (HR) is a vital process for repairing DNA double-strand breaks. Germline variants in the HR pathway, comprising at least 10 genes, such as BRCA1, BRCA2, ATM, BARD1, BRIP1, CHEK2, NBS1(NBN), PALB2, RAD51C, and RAD51D, lead to inherited susceptibility to specific types of cancers, including those of the breast, ovaries, prostate, and pancreas. The penetrance of germline pathogenic variants of each gene varies, whereas all their associated protein products are indispensable for maintaining a high-fidelity DNA repair system by HR. The present review summarizes the basic molecular mechanisms and components that collectively play a role in maintaining genomic integrity against DNA double-strand damage and their clinical implications on each type of hereditary tumor.

Recurrent Germline Mutations of CHEK2 as a New Susceptibility Gene in Patients with Pheochromocytomas and Paragangliomas

Purpose. Recently, pheochromocytomas and paragangliomas (PPGLs) have been strongly suspected as hereditary tumors, as approximately 40% of patients carry germline mutations. In the cancers where defects occur to corrupt DNA repair and facilitate tumorigenesis, a CHEK2 strong association has been observed. Therefore, the purpose of this study was to investigate the effect of CHEK2 mutations for its possible pathogenicity in PPGLs. Methods. Four patients with CHEK2 mutations were recruited, as previously detected by the whole exome sequencing. Sanger sequencing was used to verify the germline mutations as well as the loss of heterozygosities (LOHs) in their somatic DNAs. Immunohistochemistry was used to analyze the expression of CHEK2 and its downstream target p53 Ser20 (phosphorylated p53). Results. The average age of studied patients was 44.25 ± 11.18 years, at the time diagnosis. One patient had multiple tumors which recurred quickly, while two patients had distant metastasis. None of the patient had any relevant family history. Four germline CHEK2 mutations were identified (c.246_260del; c.715G > A; c.1008+3A > T; and c.1111C > T). All the patients were predicted to have either pathogenic or suspected pathogenic mutations. There was no LOH of CHEK2 gene in somatic DNAs found. Additionally, neither CHEK2 proteins nor its downstream target p53 Ser20 were expressed in the tumor tissues. The inactivation of CHEK2 leads to the decrease in the p53 phosphorylation, which might promote tumorigenesis. Conclusions. For the first time, CHEK2 was identified as a susceptibility gene for PPGLs. However, the penetrance of CHEK2 gene with genotype-phenotype correlation needs to be investigated.

Correlation between Family RB1 Gene Pathogenic Variant with Clinical Features and Prognosis of Retinoblastoma under 5 Years Old

Retinoblastoma (RB) is the most common primary intraocular malignant tumor in infants and the prototype of human hereditary tumors. Its occurrence and development are closely related to the pathogenic variant of tumor suppressor RB1 gene. We aim to analyze the characteristics of RB1 gene pathogenic variant and clinical phenotype in retinoblastoma patients and their relatives. Children with RB were recruited from August 2007 to November 2017. QT-PCR, probing, and gene sequencing were used to analyze the sequence of RB1 gene in RB children, their parents, or grandparents with a clear history of illness. The SPSS20.0 software was used to analyze the correlation between polymorphisms of RB1 gene and the incidence and prognosis of the enrolled children and relatives. 40 RB children (20 males and 20 females) were recruited, unilateral RB accounted for 52.5% (21/40), bilateral RB accounted for 42.5% (17/40), and trilateral RB accounted for 5.0% (2/40). 6 patients had a clear family history (15.0%, 6/40). It had been verified that 19 probands (47.5%) have RB1 gene pathogenic variants (11 frameshift and 8 missense pathogenic variants), of which germline inheritance accounted for 47.4% (9/19) and nongermline heredity accounted for 52.6% (10/19). Pathogenic variants of 10 nucleic acid sites without reported were found, among which c.2455C>G (p.L819V) was confirmed to have heterozygous pathogenic variants in both a bilateral RB patient and his mother with unilateral RB. Family genetic high-risk factors, bilateral/trilateral RB, >12-month-onset RB have a higher proportion of RB1 gene pathogenic variant than children with no family history, unilateral RB, and ≤12-month ( P = 0.021 , 0.001,0.034). The proportion of pedigree inheritance of infantile retinoblastoma with bilateral disease is high. There was a certain proportion of RB1 gene pathogenic variant in 3-5-year-old children with bilateral RB, even if they had no family genetic history. Therefore, the detection of RB1 gene pathogenic variant should not only focus on infants but also on the phenotype of RB1 gene pathogenic variant in children over 3 years old with bilateral eye disease.

Anaesthetic Management for Laparascopic Adrenalectomy for Pheochromocytoma as Part of Vonn Hippel-Lindau Syndrome in Child

Pheochromocytoma is a tumor that originates from either chromaffincells in adrenal medulla or in other paraganglia tissues (paragangliomas) of the sympathetic nervous system. It might be familial and associated with hereditary tumors such as Von Hippel-Lindau syndrome and multiple endocrine neoplasia type II. The symptoms are variable related to the level of secreted catecholamine. The most common are hypertension, tachycardia, headache and abdominal pain. The most effective treatment is surgical resection as in recent years, laparoscopic surgery has been more preferred. The perioperative management is quite challenging especially in view of hemodynamic fluctuations. Although there is a considerable amount of information on the management of the adult with phaeochromocytoma, much less has been written concerning children with the disease. We present a case of 9-year-old hypertensive boy with left sided pheochromocytoma, scheduled for excision of tumour. He had presented with complaints of pain in abdomen, excessive sweating, headache and raised blood pressure, as well as family anamnesis for von Hippel-Lindau syndrome (father with confirmed diagnosis). Diagnosis was confirmed by CT scan (abdomen), raised 24-hour urinary catecholamine levels and genetics tests. Preoperative blood pressure was controlled with prazosin (ά-adrenergic blocker). The anaesthetic technique used was general anaesthesia. Child was later discharged on oral antihypertensive.

Clinical and genetic characterization of cancer patients with multiple germline variants.

e22523 Background: Hereditary tumors are generally monogenic diseases with autosomal dominant inheritance. However, we noticed that some individuals may harbor ≥2 germline mutations in one or multiple genes, which remains to be explored. Methods: Genetic mutations were reviewed in more than 50,000 cancer patients who underwent hybridization capture based next-generation sequencing (NGS). Germline variants were interpreted following ACMG guideline, and only pathogenic and likely pathogenic variants were included in this study. Results: Multiple germline variants were identified in 42 individuals with the detection rate of 0.075%. The median age at diagnosis was 48 years (range 31-73). Two thirds of patients were female and 26.2% of patients has cancer family history. Prostate cancer is the most common cancer type (0.6%, 2/332), followed by carcinomas of ovarian or fallopian tube (0.48%, 7/1461), breast (0.24%, 8/3302), pancreas (0.2%, 2/982) and so on. Surprisingly, 7 patients with lung cancer also harbored ≥2 germline mutations (0.02%). Most of these germline variants affected DNA damage repair pathways [75.6% homologous recombination repair (HR), 8.1% mismatch repair (MMR), 1.2% base excision repair (BER)]. Four patients had two germline variants identified on a single gene (2 ATM, 1 BRCA1, 1 BRCA2). Three variants were identified in 2 patients, and 2 variants were identified in the remaining 36 patients. Two or more germline variants in HRR pathway were identified in 64.3% of patients, among which 18.5% patients had BRCA1+ BRCA2 double variants. The efficacy of poly ADP-ribose polymerase inhibitors (PARPi) in this specific population should raise concern. Besides, double variants in HRR and MMR pathway were found in 5 patients, which suggested the potential benefit of immunotherapy and PARPi combination therapy. Conclusions: In addition to identify variants contributing to the personal and family cancer history, NGS can accidentally identify germline variants that may suggest the susceptibility of other hereditary tumors. Multiple variants on HRR or MMR genes may have important implications for the treatment strategy for these patients.

GIPC2 is an endocrine-specific tumor suppressor gene for both sporadic and hereditary tumors of RET- and SDHB-, but not VHL-associated clusters of pheochromocytoma/paraganglioma

Pheochromocytoma/paraganglioma (PPGL) is an endocrine tumor of the chromaffin cells in the adrenal medulla or the paraganglia. Currently, about 70% of PPGLs can be explained by germline or somatic mutations in several broadly expressed susceptibility genes including RET, VHL, and SDHB, while for the remaining, mainly sporadic cases, the pathogenesis is still unclear. Even for known susceptible genes, how mutations in these mostly ubiquitous genes result in tissue-specific pathogenesis remains unanswered, and why RET-mutated tumors almost always occur in the adrenal while SDHB-mutated tumors mostly occur extra-adrenal remains a mystery. By analyzing 22 sporadic PPGLs using SNP 6.0 genotyping arrays combined with expression profiling of 4 normal and 4 tumor tissues, we identified GIPC2, a gene located at 1p31.1 with preferential expression in adrenal and inducible by adrenal glucocorticoid, as a novel putative tumor suppressor gene for PPGLs. Copy number deletion and GIPC2 promoter hypermethylation but not GIPC2 mutation, accompanied with reduced GIPC2 expression, were observed in 39 of 55 PPGLs in our cohort. Examination of a published expression database consisting of 188 PPGLs found little GIPC2 expression in Cluster 1A (SDHx-associated) and Cluster 2A (NF1/RET-associated) tumors, but less pronounced reduction of GIPC2 expression in Cluster 1B (VHL-associated) and Cluster 2B/2C tumors. GIPC2 induced p27, suppressed MAPK/ERK and HIF-1ɑ pathways as well as cancer cell proliferation. Overexpressing GIPC2 in PC12 cells inhibited tumor growth in nude mice. We found GIPC2 interacted with the nucleoprotein NONO and both proteins regulated p27 transcription through the same GGCC box on p27 promoter. Significantly, low expression of both GIPC2 and p27 was associated with shorter disease-free survival time of PPGLs patients in the TCGA database. We found that PPGL-causing mutations in RET and in SDHB could lead to primary rat adrenal chromaffin cell proliferation, ERK activation, and p27 downregulation, all requiring downregulating GIPC2. Notably, the RET-mutant effect required the presence of dexamethasone while the SDHB-mutant effect required its absence, providing a plausible explanation for the tumor location preference. In contrast, the PPGL-predisposing VHL mutations had no effect on proliferation and GIPC2 expression but caused p53 downregulation and reduced apoptosis in chromaffin cells compared with wild-type VHL. Thus, our study raises the importance of cortical hormone in PPGL development, and GIPC2 as a novel tumor suppressor provides a unified molecular mechanism for the tumorigenesis of both sporadic and hereditary tumors of Clusters 1A and 2A concerning SDHB and RET, but not tumors of Cluster 1B concerning VHL and other clusters.

Evidence-based clinical practice guidelines for management of colorectal polyps

Background The Japanese Society of Gastroenterology (JSGE) published ‘‘Daicho Polyp Shinryo Guideline 2014′’ in Japanese and a part of this guideline was published in English as “Evidence-based clinical practice guidelines for management of colorectal polyps” in the Journal of Gastroenterology in 2015. A revised version of the Japanese-language guideline was published in 2020, and here we introduce a part of the contents of revised version. Methods The guideline committee discussed and drew up a series of clinical questions (CQs). Recommendation statements for the CQs were limited to items with multiple therapeutic options. Items with established conclusions that had 100% agreement with previous guidelines (background questions) and items with no (or old) evidence that are topics for future research (future research questions: FRQs) were given descriptions only. To address the CQs and FRQs, PubMed, ICHUSHI, and other sources were searched for relevant articles published in English from 1983 to October 2018 and articles published in Japanese from 1983 to November 2018. The Japan Medical Library Association was also commissioned to search for relevant materials. Manual searches were performed for questions with insufficient online references. Results The professional committee created 18 CQs and statements concerning the current concept and diagnosis/treatment of various colorectal polyps, including their epidemiology, screening, pathophysiology, definition and classification, diagnosis, management, practical treatment, complications, and surveillance after treatment, and other colorectal lesions (submucosal tumors, nonneoplastic polyps, polyposis, hereditary tumors, ulcerative colitis-associated tumors/carcinomas). Conclusions After evaluation by the moderators, evidence-based clinical practice guidelines for management of colorectal polyps were proposed for 2020. This report addresses the therapeutic related CQs introduced when formulating these guidelines.