The Kindlin
protein family, comprising Kindlin-1, Kindlin-2 and Kindlin-3, play important roles in various human
cancers. Here, to explore the clinical significance of Kindlins in human
osteosarcomas, quantitative real-time PCR and Western blot analyses were performed to detect the expression of Kindlin-1, Kindlin-2 and Kindlin-3 mRNAs and
proteins in 20 self-pairs of
osteosarcoma and adjacent noncancerous tissues. Then, immunohistochemistry was performed to examine subcellular localizations and expression patterns of Kindlin
proteins in 100
osteosarcoma and matched adjacent noncancerous tissues. Kindlin-1, Kindlin-2 and Kindlin-3
protein immunostainings were localized in the cytoplasm, nucleus and cytoplasm, respectively, of
tumor cells in primary
osteosarcoma tissues. Statistically, the expression levels of Kindlin-1 and Kindlin-2 mRNAs and
proteins in
osteosarcoma tissues were all significantly higher (both P<0.01), but those of Kindlin-3
mRNA and
protein were both dramatically lower (both P<0.05), than in matched adjacent noncancerous tissues. In addition, the overexpressions of Kindlin-1 and Kindlin-2
proteins were both significantly associated with high
tumor grade (both P=0.01), presence of
metastasis (both P=0.006), recurrence (both P=0.006) and poor response to
chemotherapy (both P=0.02). Moreover, Kindlin-1 and Kindlin-2 expressions were both identified as independent prognostic factors for overall (both P=0.01) and disease-free (P=0.02 and 0.01, respectively) survivals of
osteosarcoma patients. However, no associations were observed between Kindlin-3 expression and various clinicopathologic features and patients' prognosis. In conclusion, aberrant expression of Kindlin-1 and Kindlin-2 may function as reliable markers for progression and prognosis in
osteosarcoma patients, especially for
tumor recurrence.