# Mesothelial cells promote peritoneal invasion and metastasis of ascites-derived ovarian cancer cells through spheroid formation **Authors:** Kaname Uno, Masato Yoshihara, Yoshihiko Yamakita, Kazuhisa Kitami, Shohei Iyoshi, Mai Sugiyama, Yoshihiro Koya, Tomihiro Kanayama, Haruhito Sahara, Satoshi Nomura, Kazumasa Mogi, Emiri Miyamoto, Hiroki Fujimoto, Kosuke Yoshida, Satoshi Tamauchi, Akira Yokoi, Nobuhisa Yoshikawa, Kaoru Niimi, Yukihiro Shiraki, Jonas Sjölund, Hidenori Oguchi, Kristian Pietras, Atsushi Enomoto, Akihiro Nawa, Hiroyuki Tomita, Hiroaki Kajiyama PMC · DOI: 10.1126/sciadv.adu5944 · Science Advances · 2026-02-06 ## TL;DR Ovarian cancer cells form spheroids with mesothelial cells in ascites, which helps the cancer spread rapidly in the abdominal cavity. ## Contribution The study reveals that mesothelial cells in ascites promote ovarian cancer metastasis through spheroid formation. ## Key findings - Almost all EOC cells form spheroids, with 60% containing mesothelial cells. - Aggregated cancer-mesothelial spheroids invade collagen or mesothelial layers. - Mesothelial cells in spheroids show significant RNA expression changes, aiding cancer invasion. ## Abstract Patients with epithelial ovarian cancer (EOC) are often diagnosed with peritoneal metastasis and ascites, the accumulation of intraperitoneal fluid containing nonmalignant cells. However, the interactions between EOC and nonmalignant cells before peritoneal metastasis remain unclear. To investigate this, whole EOC spheroids were observed using a multiphoton microscope, and their invasion ability was assessed. Mesothelial cells were identified as notable components of ascites through morphological assessment, immunohistochemical/immunofluorescence staining, and single-cell RNA sequencing analyses. Almost all EOC cells were spheroids, with 60% containing mesothelial cells. EOC cells quickly generate aggregated spheroids with mesothelial cells, and these aggregated cancer-mesothelial spheroids (ACMSs) invade collagen or mesothelial layers. Mesothelial cells forming ACMSs initiated the invasion. RNA sequencing analysis revealed marked RNA expression changes in mesothelial cells, whereas the changes in EOC cells were minor. Transforming growth factor–β1–stimulated mesothelial cells showed increased invadopodium formation along with fascin-1 up-regulation. These findings suggest that EOC cells alter mesothelial cells through ACMSs, thereby elucidating the rapid spread of EOC in the abdominal cavity. Ovarian cancer cells form spheroids with surrounding mesothelial cells in the ascites, altering them to facilitate metastasis. ## Linked entities - **Proteins:** Fscn1 (fascin actin-bundling protein 1) - **Diseases:** ovarian cancer (MONDO:0005140), epithelial ovarian cancer (MONDO:0005140) ## Full-text entities - **Genes:** PDPN (podoplanin) [NCBI Gene 10630] {aka AGGRUS, D2-40, GP36, GP40, Gp38, HT1A-1}, CD8A (CD8 subunit alpha) [NCBI Gene 925] {aka CD8, CD8alpha, IMD116, Leu2, p32}, Upk3b (uroplakin 3B) [NCBI Gene 100647] {aka P35, PMS2L14, UpIIIb}, PAX8 (paired box 8) [NCBI Gene 7849] {aka PAX-8}, MYO10 (myosin X) [NCBI Gene 4651] {aka MyoX}, Calb2 (calbindin 2) [NCBI Gene 12308] {aka CR}, Fscn1 (fascin actin-bundling protein 1) [NCBI Gene 14086] {aka Fan1, fascin-1}, FBLN1 (fibulin 1) [NCBI Gene 2192] {aka FBLN, FIBL1}, Apc (APC, WNT signaling pathway regulator) [NCBI Gene 11789] {aka CC1, Min, mAPC}, Vim (vimentin) [NCBI Gene 22352], Krt8 (keratin 8) [NCBI Gene 16691] {aka Card2, EndoA, K8, Krt-2.8, Krt2-8, TROMA-1}, COL6A1 (collagen type VI alpha 1 chain) [NCBI Gene 1291] {aka BTHLM1, BTHLM1A, OPLL, UCHMD1, UCHMD1A}, CLDN4 (claudin 4) [NCBI Gene 1364] {aka CPE-R, CPER, CPETR, CPETR1, WBSCR8, hCPE-R}, ITGB1 (integrin subunit beta 1) [NCBI Gene 3688] {aka CD29, FNRB, GPIIA, MDF2, MSK12, VLA-BETA}, CTTN (cortactin) [NCBI Gene 2017] {aka EMS1}, SH3PXD2A (SH3 and PX domains 2A) [NCBI Gene 9644] {aka FISH, SH3MD1, TKS5}, MMP9 (matrix metallopeptidase 9) [NCBI Gene 4318] {aka CLG4B, GELB, MANDP2, MMP-9}, Tgfb1 (transforming growth factor, beta 1) [NCBI Gene 21803] {aka TGF-beta1, TGFbeta1, Tgfb, Tgfb-1}, Krt7 (keratin 7) [NCBI Gene 110310] {aka D15Wsu77e, K7, Krt2-7}, Trp53-ps (transformation related protein 53, pseudogene) [NCBI Gene 22060], Des (desmin) [NCBI Gene 13346], ARID1A (AT-rich interaction domain 1A) [NCBI Gene 8289] {aka B120, BAF250, BAF250a, BM029, C1orf4, CSS2}, DCN (decorin) [NCBI Gene 1634] {aka CSCD, DSPG2, PG40, PGII, PGS2, SLRR1B}, Lrrn4 (leucine rich repeat neuronal 4) [NCBI Gene 320974] {aka B430119L13Rik, Nlrr4}, KRT8 (keratin 8) [NCBI Gene 3856] {aka CARD2, CK-8, CK8, CYK8, K2C8, K8}, Msln (mesothelin) [NCBI Gene 56047] {aka C-ERC, MPF}, LRRN4 (leucine rich repeat neuronal 4) [NCBI Gene 164312] {aka C20orf75, NLRR-4, NLRR4, dJ1056H1.1}, ANXA5 (annexin A5) [NCBI Gene 308] {aka ANX5, CPB-I, ENX2, HEL-S-7, PP4, RPRGL3}, UPK3B [NCBI Gene 80761], VIM (vimentin) [NCBI Gene 7431], Myo10 (myosin X) [NCBI Gene 17909] {aka D15Ertd600e, mKIAA0799, myosin-X}, Cort (cortistatin) [NCBI Gene 12854] {aka CST, PCST}, COL1A1 (collagen type I alpha 1 chain) [NCBI Gene 1277] {aka CAFYD, EDSARTH1, EDSC, OI1, OI2, OI3}, Wt1 (WT1 transcription factor) [NCBI Gene 22431] {aka D630046I19Rik, Wt-1}, SLPI (secretory leukocyte peptidase inhibitor) [NCBI Gene 6590] {aka ALK1, ALP, BLPI, HUSI, HUSI-1, HUSI-I}, KRAS (KRAS proto-oncogene, GTPase) [NCBI Gene 3845] {aka 'C-K-RAS, C-K-RAS, CFC2, K-RAS2A, K-RAS2B, K-RAS4A}, TP53 (tumor protein p53) [NCBI Gene 7157] {aka BCC7, BMFS5, LFS1, P53, TRP53}, LUM (lumican) [NCBI Gene 4060] {aka LDC, SLRR2D}, Krt18 (keratin 18) [NCBI Gene 16668] {aka CK18, K18, Krt1-18}, Acta2 (actin alpha 2, smooth muscle, aorta) [NCBI Gene 11475] {aka 0610041G09Rik, Actvs, SMAalpha, SMalphaA, a-SMA, alphaSMA}, Cdh2 (cadherin 2) [NCBI Gene 12558] {aka CDHN, N-CAD, Ncad}, HIF1A (hypoxia inducible factor 1 subunit alpha) [NCBI Gene 3091] {aka HIF-1-alpha, HIF-1A, HIF-1alpha, HIF1, HIF1-ALPHA, MOP1}, EPCAM (epithelial cell adhesion molecule) [NCBI Gene 4072] {aka Ber-Ep4, BerEp4, DIAR5, EGP-2, EGP314, EGP40}, UPK3B (uroplakin 3B) [NCBI Gene 105375355] {aka P35, UP3B, UPIIIB}, EGF (epidermal growth factor) [NCBI Gene 1950] {aka HOMG4, URG}, POTEF (POTE ankyrin domain family member F) [NCBI Gene 728378] {aka A26C1B, POTE2alpha, POTEACTIN}, LGR5 (leucine rich repeat containing G protein-coupled receptor 5) [NCBI Gene 8549] {aka FEX, GPR49, GPR67, GRP49, HG38}, ACTA2 (actin alpha 2, smooth muscle) [NCBI Gene 59] {aka ACTSA, SMDYS}, KRT18 (keratin 18) [NCBI Gene 3875] {aka CK-18, CYK18, K18}, FAP (fibroblast activation protein alpha) [NCBI Gene 2191] {aka DPPIV, FAPA, FAPalpha, SIMP}, FSCN1 (fascin actin-bundling protein 1) [NCBI Gene 6624] {aka HSN, SNL, p55}, DES (desmin) [NCBI Gene 1674] {aka CDCD3, CSM1, CSM2, LGMD1D, LGMD1E, LGMD2R}, WT1 (WT1 transcription factor) [NCBI Gene 7490] {aka AWT1, GUD, NPHS4, WAGR, WIT-2, WT-1}, MSLN (mesothelin) [NCBI Gene 10232] {aka MPF, SMRP}, MUC16 (mucin 16, cell surface associated) [NCBI Gene 94025] {aka CA125}, MMP14 (matrix metallopeptidase 14) [NCBI Gene 4323] {aka MMP-14, MMP-X1, MT-MMP, MT-MMP 1, MT1-MMP, MT1MMP}, PDGFRA (platelet derived growth factor receptor alpha) [NCBI Gene 5156] {aka CD140A, PDGFR-2, PDGFR2}, EREG (epiregulin) [NCBI Gene 2069] {aka EPR, ER, Ep}, CALB2 (calbindin 2) [NCBI Gene 794] {aka CAB29, CAL2, CR}, TGFB1 (transforming growth factor beta 1) [NCBI Gene 7040] {aka CAEND1, CED, DPD1, IBDIMDE, LAP, TGF-beta1} - **Diseases:** Hypoxia (MESH:D000860), fibroma (MESH:D005350), endometrioid carcinoma (MESH:D018269), Metastasis (MESH:D009362), serous carcinoma (MESH:D018297), inflammation (MESH:D007249), EOC (MESH:D000077216), carcinogenesis (MESH:D063646), breast and pancreatic cancer (MESH:D001943), squamous cell carcinoma (MESH:D002294), I (MESH:D006969), Ascites (MESH:D001201), stage I (MESH:D062706), teratoma (MESH:D013724), gastric cancer (MESH:D013274), malignant mesothelioma (MESH:D000086002), peritoneal (MESH:D010538), ACMSs (MESH:D009369), HGSOC (MESH:D010051), II/III/IV (MESH:D006011), hypoxic (MESH:D002534) - **Chemicals:** cisplatin (MESH:D002945), SB431542 (MESH:C459179), glycerol (MESH:D005990), acetic acid (MESH:D019342), phosphatidylserine (MESH:D010718), penicillin (MESH:D010406), Triton X-100 (MESH:D017830), PFA (MESH:C003043), CaCl2 (MESH:D002122), TAM (MESH:D013629), streptomycin (MESH:D013307), oil (MESH:D009821), CellTracker Green (MESH:C069306), Coomassie Brilliant Blue (MESH:C004692), water (MESH:D014867), corn oil (MESH:D003314), paraffin (MESH:D010232), PBS (MESH:D007854), dithiothreitol (MESH:D004229), hematoxylin (MESH:D006416), polyacrylamide (MESH:C016679), FDG (MESH:D019788), methanol (MESH:D000432), 4',6-diamidino-2-phenylindole (MESH:C007293), Percoll (MESH:C016039), bromophenol blue (MESH:D001978), Alexa Fluor 488 (MESH:C000711379), Ca (MESH:D002118), 7-AAD (MESH:C025942), ZnCl2 (MESH:C016837), SDS (MESH:D012967), formalin (MESH:D005557), puromycin (MESH:D011691), citrate (MESH:D019343), luciferin (MESH:D000090562), FITC (-), phalloidin (MESH:D010590), Green (MESH:C024537), acrylamide (MESH:D020106) - **Species:** Mus musculus (house mouse, species) [taxon 10090], Homo sapiens (human, species) [taxon 9606], Solanum lycopersicum (tomato, species) [taxon 4081], Mycoplasma (genus) [taxon 2093], Adeno-associated virus (species) [taxon 272636] - **Cell lines:** O90 — Mus musculus (Mouse), Hybridoma (CVCL_L845), HBME1 — Rattus norvegicus (Rat), Spontaneously immortalized cell line (CVCL_C7RQ), OVCAR3 — Homo sapiens (Human), High grade ovarian serous adenocarcinoma, Cancer cell line (CVCL_0465), LP9 — Homo sapiens (Human), Finite cell line (CVCL_E109), SCC145 — Siniperca chuatsi (Mandarin fish), Spontaneously immortalized cell line (CVCL_C0WY), luc — Mus musculus (Mouse), Mouse glioblastoma, Cancer cell line (CVCL_ZJ60), SKOV3 — Homo sapiens (Human), Ovarian serous cystadenocarcinoma, Cancer cell line (CVCL_0532), ES2 — Homo sapiens (Human), Embryonic stem cell (CVCL_C769), BJ — Homo sapiens (Human), Telomerase immortalized cell line (CVCL_6573), ID8 — Mus musculus (Mouse), Spontaneously immortalized cell line (CVCL_IU14), /c — Mus musculus (Mouse), Hepatocellular carcinoma of the mouse, Cancer cell line (CVCL_9103), Kuramochi — Homo sapiens (Human), High grade ovarian serous adenocarcinoma, Cancer cell line (CVCL_1345), CVCL_1345 — Homo sapiens (Human), Duchenne muscular dystrophy, Induced pluripotent stem cell (CVCL_YQ58), OV90 — Homo sapiens (Human), Ovarian adenocarcinoma, Cancer cell line (CVCL_3768), A2780 — Homo sapiens (Human), Ovarian endometrioid adenocarcinoma, Cancer cell line (CVCL_0134), CVCL_0134 — Homo sapiens (Human), Finite cell line (CVCL_L958) ## Full text _Full body text omitted from this summary view._ Fetch the complete paper as Markdown: https://tomesphere.com/paper/PMC12880548/full.md ## Figures 8 figures with captions in the complete paper: https://tomesphere.com/paper/PMC12880548/full.md ## References 87 references — full list in the complete paper: https://tomesphere.com/paper/PMC12880548/full.md --- Source: https://tomesphere.com/paper/PMC12880548