Clinicopathological roles of aberrantly expressed recoverin in malignant tumor cells.
OBJECTIVE
Cancer-associated retinopathy (CAR) is an ocular manifestation of a paraneoplastic syndrome whereby immunological reactions toward recoverin, a retina-specific calcium binding protein, and other retinal antigens aberrantly expressed in tumor cells are elicited. As a consequence, photoreceptor cell degeneration is induced. To elucidate the pathological role of the aberrantly expressed recoverin, we studied the recoverin expression levels in various malignant tumors and the effects of the expressed recoverin on the sensitivity to anti-cancer drugs.


METHODS
Recoverin expression levels were determined by immunohistochemistry with anti-human recoverin monoclonal antibody on multiple tissue arrays obtained from several lung, stomach, colon and other cancers. In the presence of several anti-cancer drugs, including anti-tumor antibiotics, plant alkaloids and anti-metabolites, cytotoxicity assay was performed using recoverin-positive or recoverin-negative A549 cells originating from human lung adenocarcinoma.


RESULTS
Immunofluorescence labeling revealed that recoverin immunoreactivities were detected at approximately 10-40% of malignant tumor tissues. Cytotoxic effects by anti-cancer drugs were higher in recoverin-positive A549 cells as compared to recoverin-negative cells.


CONCLUSIONS
The present data may correlate with the previous observation that recoverin-expressing cancer cells induced tumor immunity and a favorable prognosis for primary cancer in CAR patients.
Matsuo
Sachiyo
S
Department of Ophthalmology, Sapporo Medical University School of Medicine, Sapporo, Japan.
Ohguro
Hiroshi
H
Ohguro
Ikuyo
I
Nakazawa
Mitsuru
M
D000970:Antineoplastic Agents / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019084:Fluorescent Antibody Technique, Indirect; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D006801:Humans; D009369:Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology*; D051603:Recoverin / Q000235:genetics* / Q000378:metabolism; D014162:Transfection
D000970:Antineoplastic Agents; C496731:RCVRN protein, human; D051603:Recoverin