The decrease in NKG2D+ Natural Killer cells in peripheral blood of patients with metastatic colorectal cancer.
BACKGROUND
Natural killer (NK) cells play important roles in the immune defense against tumors such as colorectal cancer. In humans, NKG2D is an activating immune receptor constitutively expressed in most cytotoxic lymphocytes including NK and CD8+ T cells. In this study, the expression of NKG2D molecule was investigated in peripheral blood NK cells from colorectal cancer patients and compared with healthy subjects.


METHODS
We studied 21 non-metastatic (low-grade), 17 non-metastatic (high-grade), 16 metastatic colorectal cancer patients, and 24 healthy controls. Peripheral blood samples were obtained to isolate peripheral blood mononuclear cells (PBMCs) and the percentage of peripheral blood NKG2D+CD3-CD56+ NK cells was analyzed by flow cytometry. The expression of NKG2D at mRNA level was also measured by real-time PCR in both, patients and control subjects.


RESULTS
The results showed a significant reduction in the percentage of NKG2D+NK cells as well as NKG2D mRNA expression in peripheral blood of metastatic colon cancer patients.


CONCLUSIONS
This result suggests that decreased expression of activating NKG2D receptor in metastatic colorectal cancer might compromise NK cell function and allow tumor to evade immunity (Tab. 3, Fig. 4, Ref. 33).
M
M
Gharagozloo
H
H
Kalantari
A
A
Rezaei
M R
MR
Maracy
M
M
Salehi
A
A
Bahador
N
N
Hassannejad
M
M
Narimani
M H
MH
Sanei
B
B
Bayat
H
H
Ghazanfari
D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000276:immunology* / Q000473:pathology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology*; D007963:Leukocytes, Mononuclear; D008297:Male; D008875:Middle Aged; D055655:NK Cell Lectin-Like Receptor Subfamily K / Q000235:genetics / Q000276:immunology*; D009362:Neoplasm Metastasis; D012333:RNA, Messenger / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction
C527085:KLRK1 protein, human; D055655:NK Cell Lectin-Like Receptor Subfamily K; D012333:RNA, Messenger
NK cells; NKG2D.; colorectal cancer; metastasis