title: Exosomes in colorectal carcinoma formation: ALIX under the magnifying glass.
abstract: Exosomes are small membrane vesicles that have important roles in transporting a great variety of bioactive molecules between epithelial compartment and their microenvironment during tumor formation including colorectal adenoma-carcinoma sequence. We tested the mRNA expression of the top 25 exosome-related markers based on ExoCharta database in healthy (n=49), adenoma (n=49) and colorectal carcinoma (n=49) patients using Affymetrix HGU133 Plus2.0 microarrays. Most related genes showed significantly elevated expression including PGK1, PKM, ANXA5, ENO1, HSP90AB1 and MSN during adenoma-carcinoma sequence. Surprisingly, the expression of ALIX (ALG 2-interacting protein X), involved in multivesicular body (MVB) and exosome formation, was significantly reduced in normal vs adenoma (P=5.02 × 10(-13)) and in normal vs colorectal carcinoma comparisons (P=1.51 × 10(-10)). ALIX also showed significant reduction (P<0.05) at the in situ protein level in the epithelial compartment of adenoma (n=35) and colorectal carcinoma (n=37) patients compared with 27 healthy individuals. Furthermore, significantly reduced ALIX protein levels were accompanied by their gradual transition from diffuse cytoplasmic expression to granular signals, which fell into the 0.6-2 μm diameter size range of MVBs. These ALIX-positive particles were seen in the tumor nests, including tumor-stroma border, which suggest their exosome function. MVB-like structures were also detected in tumor microenvironment including α-smooth muscle actin-positive stromal cells, budding off cancer cells in the tumor front as well as in cancer cells entrapped within lymphoid vessels. In conclusion, we determined the top aberrantly expressed exosome-associated markers and revealed the transition of diffuse ALIX protein signals into a MVB-like pattern during adenoma-carcinoma sequence. These tumor-associated particles seen both in the carcinoma and the surrounding microenvironment can potentially mediate epithelial-stromal interactions involved in the regulation of tumor growth, metastatic invasion and therapy response.
authors.affiliation: Molecular Medicine Research Unit, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Valcz
authors.affiliation: Molecular Medicine Research Unit, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Orsolya
authors.initials: O
authors.lastname: Galamb
authors.affiliation: 1st Department of Pathology and Experimental Cancer Research, Semmelweis University and MTA-SE Tumor Progression Research Group, Budapest, Hungary.
authors.forename: Tibor
authors.initials: T
authors.lastname: Krenács
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA.
authors.forename: Sándor
authors.initials: S
authors.lastname: Spisák
authors.affiliation: 2nd Department of Internal Medicine, Semmelweis University, Budapest, Hungary.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Kalmár
authors.affiliation: 2nd Department of Internal Medicine, Semmelweis University, Budapest, Hungary.
authors.forename: Árpád V
authors.initials: ÁV
authors.lastname: Patai
authors.affiliation: Molecular Medicine Research Unit, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Barna
authors.initials: B
authors.lastname: Wichmann
authors.affiliation: Department of General Surgery and Surgical Oncology, Uzsoki Teaching Hospital, Budapest, Hungary.
authors.forename: Kristóf
authors.initials: K
authors.lastname: Dede
authors.affiliation: Molecular Medicine Research Unit, Hungarian Academy of Sciences, Budapest, Hungary.|2nd Department of Internal Medicine, Semmelweis University, Budapest, Hungary.
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Tulassay
authors.affiliation: Molecular Medicine Research Unit, Hungarian Academy of Sciences, Budapest, Hungary.|2nd Department of Internal Medicine, Semmelweis University, Budapest, Hungary.
authors.forename: Béla
authors.initials: B
authors.lastname: Molnár
mesh_terms: D000236:Adenoma / Q000737:chemistry* / Q000235:genetics / Q000473:pathology; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis* / Q000235:genetics; D002135:Calcium-Binding Proteins / Q000032:analysis* / Q000235:genetics; D002277:Carcinoma / Q000737:chemistry* / Q000235:genetics / Q000473:pathology; D016022:Case-Control Studies; D018797:Cell Cycle Proteins / Q000032:analysis* / Q000235:genetics; D015179:Colorectal Neoplasms / Q000737:chemistry* / Q000235:genetics / Q000473:pathology; D056827:Endosomal Sorting Complexes Required for Transport / Q000032:analysis* / Q000235:genetics; D055354:Exosomes / Q000737:chemistry* / Q000235:genetics / Q000473:pathology; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D057146:Multivesicular Bodies / Q000737:chemistry* / Q000235:genetics / Q000473:pathology; D020411:Oligonucleotide Array Sequence Analysis; D059016:Tumor Microenvironment
chemical_list: D014408:Biomarkers, Tumor; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D056827:Endosomal Sorting Complexes Required for Transport; C117020:PDCD6IP protein, human