Human papillomavirus DNA, HPV L1 capsid protein and p16^INK4a protein as markers to predict cervical lesion progression

Cervical cancer is the most common malignant tumors in women leading to serious morbidity and mortality worldwide, especially among developing countries. A main cause of the disease is the high-risk human papillomavirus (HR-HPV) infection. HSIL usually progress to cervical cancer, and low-grade lesions, including LSIL and ASCUS, mostly turn to normal or benign lesions, but there are still a small number of patients who will progress to HSIL. Up to now there is no efficient biomarker clinically available to predict people with high risk to progress into HSIL. This study was conducted to evaluate the value of human papillomavirus (HPV) DNA, p16^INK4a protein, and HPV L1 capsid protein in predicting HSIL and minimizing unnecessary colposcopy treatments.

1222 patients with HR-HPV infection or with abnormal Thinprep cytologic test (TCT) were chosen to conduct colposcopy in the cervical out-patient clinic of Shanghai First Maternity and Infant Hospital affiliated to Shanghai Tongji University from June 2014 to January 2017. TCT, cervical biopsy, HPV DNA and HPVL1 were performed on all patients. 110 patients were selected to detect p16^INK4a protein. Hybrid capture 2 (HC-2) was used to detect HPV DNA, and their subgroups using gene typing system. Immunohistochemical technology was used to detect HPV L1 and p16.

HPV DNA was positive in 1097 cases, with the positive rate of 89.7% (1097/1222). In particular, the positive expression rates of HPV DNA were 82.3, 95.7, 96.6 and 100% in Normal/CC, LSIL, HSIL and cervical cancer groups, respectively (p < 0.001). HPV L1 was negative in 781 cases with HR-HPV infection, and the overall negative rate is 71.1%. In patients with Normal/CC, LSIL and HSIL, the negative expression rates of HPV L1 were 91.3, 40 and 81.2%, respectively (p value < 0.001). In the 110 patients, HPV L1 was negative in 98.1% (53/54) of Normal/CC, 42.9% (12/28) of LSIL and 85.1% (23/27) of HSIL (p value = 0.0043). P16-positive rates in patients with Normal/CC, LSIL and HSIL were 33.3% (18/54), 75% (21/28) and 96.2% (26/27), respectively (p value < 0.001). 18 out of 28 cases express low positive (+) in LSIL, 25 out of 27 cases express strong positive (3+) in HSIL. Patients with L1(−) p16(+) including 18.5% (10/54) of normal/cervicitis, 60.7% (17/28) of LSIL and 85.1% (23/27) of HSIL (p value < 0.005). Furthermore, patients with L1(−) p16(1+) included 37% (10/27) of normal/cervicitis 59.3% (16/27) of LSIL and 3.7% (1/27) of HSIL; patients with L1(−) p16(2+) consisted of 0% of normal/cervicitis/LSIL and 100% (1/1) of HSIL; patients with L1(−) p16(3+) were composed of 0% of normal/cervicitis, 4.5% (1/22) of LSIL and 95.5% (21/22) of HSIL (p value < 0.005) (Table 6).

With the increase in the degree of the cervical lesions, the expression of HPV DNA and p16 is up-regulated while HPV L1 protein is down-regulated. HPV DNA, HPV L1 and p16 are useful markers for the prediction of HSIL. Combined detection of these three markers has important potential to predicting HSIL and minimizing unnecessary colposcope examination.