Mechanical characterization of cervical squamous carcinoma cells by atomic force microscopy at nanoscale

To investigate the nanoscale mechanical properties of exfoliated cervical epithelial cells from patients to further reveal the pathogenesis of cervical cancer and help early diagnose. Exfoliated cells were collected from nine patients with chronic cervicitis or CIN1(control group), 30 patients with CIN2-3 (CIN 2-3 group), and 13 patients with cervical cancer (cervical cancer group). Stiffness of the cells was determined by atomic force microscope (AFM). Expression of P16INK4A was studied by immunocytochemistry. Environmental scanning electron microscopy was performed to observe the surface microtopography of the exfoliated cells. Young's modulus was measured for cells exfoliated from control and patients with CIN 2-3 and cervical cancer by AFM. The results showed that with increasing cervical lesions, the Young's modulus of the exfoliated cervical cells increased (P < 0.05). The modulus of the exfoliated cells was significantly decreased in the three patients 1 year after the surgery compared with the value before the surgery. Expression of P16INK4A in the exfoliated cells had not been statistically significant. Squamous cells from cervical cancer group had dense and disordered microvilli without clear microridges compare to other groups. The Young's modulus is increased from the control group, to CIN2-3 and cervical cancer groups, suggesting that the stiffness of cervical epithelial cells increases gradually with increasing cervical lesions. The changes in the mechanical properties of the exfoliated cells occur earlier than the changes in cell morphology. Therefore, analysis of mechanical properties of the exfoliated cells may be used to aid early diagnosis of the cancer.