title: Invasion of ovarian cancer cells is induced byPITX2-mediated activation of TGF-β and Activin-A.
abstract: BACKGROUND
  Most ovarian cancers are highly invasive in nature and the high burden of metastatic disease make them a leading cause of mortality among all gynaecological malignancies. The homeodomain transcription factor, PITX2 is associated with cancer in different tissues. Our previous studies demonstrated increased PITX2 expression in human ovarian tumours. Growing evidence linking activation of TGF-β pathway by homeodomain proteins prompted us to look for the possible involvement of this signalling pathway in PITX2-mediated progression of ovarian cancer.
  
  
  METHODS
  The status of TGF-β signalling in human ovarian tissues was assessed by immunohistochemistry. The expression level of TGFB/INHBA and other invasion-associated genes was measured by quantitative-PCR (Q-PCR) and Western Blot after transfection/treatments with clones/reagents in normal/cancer cells. The physiological effect of PITX2 on invasion/motility was checked by matrigel invasion and wound healing assay. The PITX2- and activin-induced epithelial-mesenchymal transition (EMT) was evaluated by Q-PCR of respective markers and confocal/phase-contrast imaging of cells.
  
  
  RESULTS
  Human ovarian tumours showed enhanced TGF-β signalling. Our study uncovers the PITX2-induced expression of TGFB1/2/3 as well as INHBA genes (p < 0.01) followed by SMAD2/3-dependent TGF-β signalling pathway. PITX2-induced TGF-β pathway regulated the expression of invasion-associated genes, SNAI1, CDH1 and MMP9 (p < 0.01) that accounted for enhanced motility/invasion of ovarian cancers. Snail and MMP9 acted as important mediators of PITX2-induced invasiveness of ovarian cancer cells. PITX2 over-expression resulted in loss of epithelial markers (p < 0.01) and gain of mesenchymal markers (p < 0.01) that contributed significantly to ovarian oncogenesis. PITX2-induced INHBA expression (p < 0.01) contributed to EMT in both normal and ovarian cancer cells.
  
  
  CONCLUSIONS
  Overall, our findings suggest a significant contributory role of PITX2 in promoting invasive behaviour of ovarian cancer cells through up-regulation of TGFB/INHBA. We have also identified the previously unknown involvement of activin-A in promoting EMT. Our work provides novel mechanistic insights into the invasive behavior of ovarian cancer cells. The extension of this study have the potential for therapeutic applications in future.
authors: Cell Biology and Physiology Division, CSIR-Indian Institute of Chemical Biology, Council of Scientific and Industrial Research, 4 Raja S. C. Mullick Road, Kolkata, 700032, India. moitrri_basu@yahoo.co.in.
authors: Moitri
authors: M
authors: Basu
authors: Cell Biology and Physiology Division, CSIR-Indian Institute of Chemical Biology, Council of Scientific and Industrial Research, 4 Raja S. C. Mullick Road, Kolkata, 700032, India. rahul.sunnybhattacharya@gmail.com.
authors: Rahul
authors: R
authors: Bhattacharya
authors: Cell Biology and Physiology Division, CSIR-Indian Institute of Chemical Biology, Council of Scientific and Industrial Research, 4 Raja S. C. Mullick Road, Kolkata, 700032, India. upasana.roy.88@gmail.com.
authors: Upasana
authors: U
authors: Ray
authors: Department of Endocrinology and Metabolism, IPGMER and SSKM Hospital, 244 AJC Bose Road, Kolkata, India. satinath.mukhopadhayay@gmail.com.
authors: Satinath
authors: S
authors: Mukhopadhyay
authors: Department of Pathology, IPGMER and SSKM Hospital, 244 AJC Bose Road, Kolkata, India. uttarac1@gmail.com.
authors: Uttara
authors: U
authors: Chatterjee
authors: Cell Biology and Physiology Division, CSIR-Indian Institute of Chemical Biology, Council of Scientific and Industrial Research, 4 Raja S. C. Mullick Road, Kolkata, 700032, India. sibsankar@iicb.res.in.
authors: Sib Sankar
authors: SS
authors: Roy
mesh_terms: D045744:Cell Line, Tumor; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D028322:Inhibin-beta Subunits / Q000096:biosynthesis / Q000235:genetics*; D009361:Neoplasm Invasiveness / Q000235:genetics / Q000473:pathology; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000473:pathology; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000235:genetics*; D000097577:Homeobox Protein PITX2
chemical_list: D018398:Homeodomain Proteins; D028322:Inhibin-beta Subunits; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D000097577:Homeobox Protein PITX2; C103008:inhibin beta A subunit