title: Molecular fixative enables expression microarray analysis of microdissected clinical cervical specimens.
abstract: Formalin-fixed tissue has been a mainstay of clinical pathology laboratories, but formalin alters many biomolecules, including nucleic acids and proteins. Meanwhile, frozen tissues contain better-preserved biomolecules, but tissue morphology is affected, limiting their diagnostic utility. Molecular fixatives promise to bridge this gap by simultaneously preserving morphology and biomolecules, enabling clinical diagnosis and molecular analyses on the same specimen. While previous reports have broadly evaluated the use of molecular fixative in various human tissues, we present here the first detailed assessment of the applicability of molecular fixative to both routine histopathological diagnosis and molecular analysis of cervical tissues. Ten specimens excised via the loop electrosurgical excision procedure, which removes conical tissue samples from the cervix, were cut into alternating pieces preserved in either formalin or molecular fixative. Cervical specimens preserved in molecular fixative were easily interpretable, despite featuring more eosinophilic cytoplasm and more recognizable chromatin texture than formalin-fixed specimens. Immunohistochemical staining patterns of p16 and Ki-67 were similar between fixatives, although Ki-67 staining was stronger in the molecular fixative specimens. The RNA of molecular fixative specimens from seven cases representing various dysplasia grades was assessed for utility in expression microarray analysis. Cluster analysis and scatter plots of duplicate samples suggest that data of sufficient quality can be obtained from as little as 50ng of RNA from molecular fixative samples. Taken together, our results show that molecular fixative may be a more versatile substitute for formalin, simultaneously preserving tissue morphology for clinical diagnosis and biomolecules for immunohistochemistry and gene expression analysis.
authors.affiliation: Integrative Oncology Department, BC Cancer Research Centre, 675 West 10th Avenue, Vancouver, BC, Canada. Electronic address: gli@bccrc.ca.
authors.forename: Gerald
authors.initials: G
authors.lastname: Li
authors.affiliation: Department of Pathology and Laboratory Medicine, BC Cancer Agency, 600 West 10th Avenue, Vancouver, BC, Canada. Electronic address: dvanniek@bccancer.bc.ca.
authors.forename: Dirk
authors.initials: D
authors.lastname: van Niekerk
authors.affiliation: Department of Obstetrics and Gynaecology, The University of British Columbia, Diamond Health Care Centre, 6th Floor, 2775 Laurel Street, Vancouver, BC, Canada. Electronic address: dianne.miller@vch.ca.
authors.forename: Dianne
authors.initials: D
authors.lastname: Miller
authors.affiliation: Department of Obstetrics and Gynaecology, The University of British Columbia, Diamond Health Care Centre, 6th Floor, 2775 Laurel Street, Vancouver, BC, Canada. Electronic address: thomas.ehlen@vch.ca.
authors.forename: Thomas
authors.initials: T
authors.lastname: Ehlen
authors.affiliation: Integrative Oncology Department, BC Cancer Research Centre, 675 West 10th Avenue, Vancouver, BC, Canada. Electronic address: cgarnis@bccrc.ca.
authors.forename: Cathie
authors.initials: C
authors.lastname: Garnis
authors.affiliation: Laura Bush Research Institute, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center at El Paso, 4801 Alberta Avenue, El Paso, TX, USA. Electronic address: michele.follen@ttuhsc.edu.
authors.forename: Michele
authors.initials: M
authors.lastname: Follen
authors.affiliation: Integrative Oncology Department, BC Cancer Research Centre, 675 West 10th Avenue, Vancouver, BC, Canada. Electronic address: mguillau@bccrc.ca.
authors.forename: Martial
authors.initials: M
authors.lastname: Guillaud
authors.affiliation: Integrative Oncology Department, BC Cancer Research Centre, 675 West 10th Avenue, Vancouver, BC, Canada. Electronic address: cmacaula@bccrc.ca.
authors.forename: Calum
authors.initials: C
authors.lastname: Macaulay
mesh_terms: D019941:Cyclin-Dependent Kinase Inhibitor p16; D005260:Female; D005557:Formaldehyde; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000737:chemistry / Q000235:genetics; D046228:Microarray Analysis; D042282:Microdissection; D009363:Neoplasm Proteins / Q000737:chemistry / Q000235:genetics; D016612:Paraffin Embedding; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D002583:Uterine Cervical Neoplasms / Q000235:genetics* / Q000473:pathology
chemical_list: C000614131:CDKN2A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D019394:Ki-67 Antigen; D009363:Neoplasm Proteins; D011506:Proteins; D005557:Formaldehyde
keywords: Cervical intraepithelial neoplasia; Gene expression microarray analysis; Immunohistochemistry; Microdissection; Molecular fixative