The use of primary patient-derived organoids for drug sensitivity and resistance testing could play an important role in precision cancer medicine. We developed expandable ovarian cancer organoids in < 3 weeks; these organoids captured the characteristics of histological cancer subtypes and replicated the mutational landscape of the primary tumours. Seven pairs of organoids (3 high-grade serous, 1 clear cell, 3 endometrioid) and original tumours shared 59.5% (36.1-73.1%) of the variants identified. Copy number variations were also similar among organoids and primary tumours. The organoid that harboured the BRCA1 pathogenic variant (p.L63*) showed a higher sensitivity to PARP inhibitor, olaparib, as well as to platinum drugs compared to the other organoids, whereas an organoid derived from clear cell ovarian cancer was resistant to conventional drugs for ovarian cancer, namely platinum drugs, paclitaxel, and olaparib. The overall success rate of primary organoid culture, including those of various histological subtypes, was 80% (28/35). Our data show that patient-derived organoids are suitable physiological ex vivo cancer models that can be used to screen effective personalised ovarian cancer drugs. Patient-derived tumour organoids have become important preclinical model systems in both cancer research and clinical settings 1. In contrast to patient-derived xenograft (PDX) mouse models that need a large amount of surgical specimen and 4-8 months for development 2 , organoids can be cultured from patient materials and can be expanded with high efficiency in a relatively short period (typically < 1 month). Organoids from mouse intestine, as well as from various other mouse and human tissues, including the colon, stomach, liver, lung, prostate, and pancreas, have been established 3,4. Patient-derived tumour organoids have also been generated from the colon, pancreas, prostate, breast, gastric, lung, oesophageal, bladder, ovarian, kidney, and liver tumour tissues 1. Organoids maintain the key genetic and phenotypic features of primary tumours, thereby, enabling their use in a broad range of applications, such drug development and identification of the best therapeutic regimen for each patient. Ovarian cancer is a devastating disease, with 295,000 new patients and 185,000 deaths each year, worldwide 5. The relative 5-year survival rate is 47% and has not apparently increased in the last 40 years. Debulking surgery with platinum-combination chemotherapy is usually administered to patients, irrespective of the histological

Matrix metalloproteinase-7 (MMP-7) (also known as matrilysin-1) is secreted as a proenzyme (proMMP-7) and plays a key role in the degradation of various extracellular matrix (ECM) and non-ECM molecules after activation. To identify the binding proteins related to proMMP-7 activation, a human lung cDNA library was screened by yeast two-hybrid system using proMMP-7 as bait. We identified a candidate molecule CD151, which is a member of the transmembrane 4 superfamily. Complex formation of proMMP-7 with CD151 was demonstrated by immunoprecipitation of the molecules from CaR-1 cells, a human rectal carcinoma cell line, expressing both proMMP-7 and CD151, and CD151 stable transfectants incubated with proMMP-7. Yeast twohybrid assays using deletion mutants of proMMP-7 and CD151 suggested an interaction between the propeptide of proMMP-7 and the COOH-terminal extracellular loop of CD151. The binding activity of 125 I-labeled proMMP-7 to CD151 on the cell membranes was shown with CD151 stable transfectants. Laser-scanning confocal microscopy demonstrated that proMMP-7 colocalizes with CD151 on the cell membranes of CD151 stable transfectants and CaR-1 cells. In situ zymography using crosslinked carboxymethylated transferrin, a substrate of MMP-7, demonstrated proteinase activity on and around CD151 stable transfectants and CaR-1 cells, while the activity was abolished by their treatment with MMP inhibitors, anti-MMP-7 antibody or anti-CD151 antibody. In human lung adenocarcinoma tissues, colocalization of MMP-7 and CD151 was demonstrated on the carcinoma cells. Metalloproteinase activity was present in these tissues and could be inhibited by antibodies to MMP-7 or CD151. These data demonstrate for the first time that proMMP-7 is captured and activated on the cell membranes through interaction with CD151, and suggest the possibility that similar to the MT1-MMP/MMP-2 system, MMP-7 is involved in the pericellular activation mechanism mediated by CD151, a crucial step in proteolysis on the cell membranes under various pathophysiological conditions including cancer invasion and metastasis.

The purposes of this study were to compare the relationships between para-aortic lymph node metastasis and various clinicopathologic factors to evaluate whether para-aortic lymph node dissection is necessary when treating endometrial cancer. A retrospective study was performed on 841 patients with endometrial cancer, who underwent the initial surgery at the Keio University Hospital. Clinicopathologic factors related to para-aortic lymph node metastasis significant on a univariate analysis were analyzed in a multivariate fashion using a logistic model. According to the multivariate analysis, the clinicopathologic factor most strongly related to the existence of para-aortic lymph node metastasis was positive pelvic lymph node metastasis (P < 0.01). Among the 155 patients who underwent pelvic and para-aortic lymph node dissection, the difference of 5-year overall survival by the presence of retroperitoneal lymph node metastasis was examined by Kaplan-Meier method. The prognosis was poor even if para-aortic lymph node dissection was performed in cases of positive para-aortic lymph node metastasis. In conclusion, when deciding whether to perform para-aortic lymph node dissection in patients with endometrial cancer, it is necessary to consider the pelvic lymph nodal status. If there is no pelvic lymph node metastasis, it could not be necessary to perform para-aortic lymph node dissection.

Ovarian cancer has a poor prognosis because early detection is difficult and recurrent ovarian cancer is usually drug-resistant. The morbidity and mortality of ovarian cancer are high worldwide and new methods of diagnosis and therapy are needed. MicroRNAs (miRNAs) are posttranscriptional regulators of gene expression that are involved in carcinogenesis, metastasis, and invasion. Thus, miRNAs are likely to be useful as diagnostic and prognostic biomarkers and for cancer therapy. Many miRNAs have altered expression in ovarian cancer compared to normal ovarian tissues and these changes may be useful for diagnosis and treatment. For example, deficiencies of enzymes including Dicer and Drosha that are required for miRNA biogenesis may be adverse prognostic factors; miRNAs such as miR-214 and miR-31, which are involved in drug resistance, and the miR-200 family, which is implicated in metastasis, may serve as biomarkers; and transfection of downregulated miRNAs and inhibition of upregulated miRNAs may be effective for treatment of ovarian cancer. Chemotherapy targeting epigenetic mechanisms associated with miRNAs may also be effective to reverse gene silencing.