Organoid cultures of early-onset colorectal cancers reveal distinct and rare genetic profiles.

OBJECTIVE: Sporadic early-onset colorectal cancer (EOCRC) has bad prognosis, yet is poorly represented by cell line models. We examine the key mutational and transcriptomic alterations in an organoid biobank enriched in EOCRCs. DESIGN: We established paired cancer (n=32) and normal organoids (n=18) from 20 patients enriched in microsatellite-stable EOCRC. Exome and transcriptome analysis was performed. RESULTS: We observed a striking diversity of molecular phenotypes, including PTPRK-RSPO3 fusions. Transcriptionally, RSPO fusion organoids resembled normal colon organoids and were distinct from APC mutant organoids, with high BMP2 and low PTK7 expression. Single cell transcriptome analysis confirmed the similarity between RSPO fusion organoids and normal organoids, with a propensity for maturation on Wnt withdrawal, whereas the APC mutant organoids were locked in progenitor stages. CRISPR/Cas9 engineered mutation of APC in normal human colon organoids led to upregulation of PTK7 protein and suppression of BMP2, but less so with an engineered RNF43 mutation. The frequent co-occurrence of RSPO fusions with SMAD4 or BMPR1A mutation was confirmed in TCGA database searches. RNF43 mutation was found in organoid from a leukaemia survivor with a novel mutational signature; and organoids with POLE proofreading mutation displayed ultramutation. The cancer organoid genomes were stable over long culture periods, while normal human colon organoids tended to be subject to clonal dominance over time. CONCLUSIONS: These organoid models enriched in EOCRCs with linked genomic data fill a gap in existing CRC models and reveal distinct genetic profiles and novel pathway cooperativity.

Functional characterization of a candidate tumor suppressor gene, Mirror Image Polydactyly 1, in nasopharyngeal carcinoma.

Mirror Image Polydactyly 1 (MIPOL1) is generally associated with congenital anomalies. However, its role in cancer development is poorly understood. Previously, by utilizing the functional complementation approach, microcell-mediated chromosome transfer (MMCT), a tumor suppressor gene, MIPOL1, was identified. MIPOL1 was confirmed to be downregulated in nasopharyngeal carcinoma (NPC) cells and tumor tissues, and re-expression of MIPOL1 induced tumor suppression. The aim of the current study is to further elucidate the functional tumor suppressive role of MIPOL1. In our study, with an expanded sample size of different clinical stages of NPC tumor tissues, we further confirmed the downregulation of MIPOL1 in different cancer stages. MIPOL1 re-expression down-regulated angiogenic factors and reduced phosphorylation of metastasis-associated proteins including AKT, p65, and FAK. In addition, MIPOL1 was confirmed to interact with a tumor suppressor, RhoB, and re-expression of MIPOL1 enhanced RhoB activity. The functional role of MIPOL1 was further validated by utilizing a panel of wild-type (WT) and truncated MIPOL1 expression constructs. The MIPOL1 tumor-suppressive effect can only be observed in the WT MIPOL1-expressing cells. In vitro and nude mice in vivo functional studies further confirmed the critical role of WT MIPOL1 in inhibiting migration, invasion and metastasis in NPC. Overall, our study provides strong evidence about the tumor-suppressive role of MIPOL1 in inhibiting angiogenesis and metastasis in NPC.

The use of supplemental external beam radiotherapy in men with low-risk prostate cancer undergoing brachytherapy before and after the 1999 American Brachytherapy Society Guideline statement.

PURPOSE: In 1999, the American Brachytherapy Society (ABS) recommended brachy-monotherapy for men with low-risk prostate cancer because of the potential for increased toxicity with combined external beam radiotherapy (EBRT) and brachytherapy without the proof of increased efficacy. We investigated the patterns of care in the community in this patient population before and after the reporting of the ABS guideline. METHODS AND MATERIALS: The study cohort consisted of 4943 men (median age, 69.0 years) with low-risk prostate cancer treated with brachytherapy with or without supplemental EBRT from 1991 to 2007 across 21 community radiation oncology centers. Multivariable logistic regression analysis was performed to determine if there was a significant association between the year of brachytherapy, prostate-specific antigen level, clinical tumor (T) category, patient's age, and the use of supplemental EBRT. RESULTS: Supplemental EBRT was used in 647 men (13%). The EBRT use initially increased until 2001 and then decreased yielding a significant association (adjusted odds ratio [AOR], 0.92; p<0.001) between the EBRT use and the year of brachytherapy using a quadratic formulation. Specifically, EBRT use peaked at 24.6% in 2001 and subsequently declined to 3.3% by 2007. Men with clinical category T2a as compared with T1c disease (AOR, 1.43; p<0.001) were more likely to receive combined modality therapy. CONCLUSIONS: The use of supplemental EBRT in men with low-risk prostate cancer treated with brachytherapy has decreased since 2001. This change in practice patterns suggests gradual adoption of the 1999 ABS practice guidelines.