Immunohistochemical detection of cytoplasmic LC3 puncta in human cancer specimens.
Autophagy is an evolutionarily conserved catabolic process that involves the entrapment of cytoplasmic components within characteristic vesicles for their delivery to and degradation within lysosomes. Alterations in autophagic signaling are found in several human diseases including cancer. Here, we describe a validated immunohistochemical protocol for the detection of LC3 puncta in human formalin-fixed, paraffin-embedded cancer specimens that can also be applied to mouse tissues. In response to systemic chemotherapy, autophagy-competent mouse tumors exhibited LC3 puncta, which did not appear in mouse cancers that had been rendered autophagy-deficient by the knockdown of Atg5 or Atg7. As compared with normal tissues, LC3 staining was moderately to highly elevated in the large majority of human cancers studied, albeit tumors of the same histological type tended to be highly heterogeneous in the number and intensity of LC3 puncta per cell. Moreover, tumor-infiltrating immune cells often were highly positive for LC3. Altogether, this protocol for LC3 staining appears suitable for the specific detection of LC3 puncta in human specimens, including tissue microarrays. We surmise that this technique can be employed for retrospective or prospective studies involving large series of human tumor samples.
INSERM, U1015, Villejuif, France.
Sylvain
S
Ladoire
Kariman
K
Chaba
Isabelle
I
Martins
Abdul Qader
AQ
Sukkurwala
Sandy
S
Adjemian
Mickaël
M
Michaud
Vichnou
V
Poirier-Colame
Felipe
F
Andreiuolo
Lorenzo
L
Galluzzi
Eileen
E
White
Mathias
M
Rosenfeldt
Kevin M
KM
Ryan
Laurence
L
Zitvogel
Guido
G
Kroemer
D000818:Animals; D045744:Cell Line, Tumor; D003593:Cytoplasm / Q000378:metabolism*; D004195:Disease Models, Animal; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology*; D013194:Staining and Labeling; D046888:Tissue Array Analysis
C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins