Human papillomavirus infection and its possible correlation with p63 expression in cervical cancer in Japan, Mongolia, and Myanmar

Abstract

Although human papillomavirus (HPV) 16 is the cause of cervical cancer in most countries including Japan, the involvement of cervical cancer with HPV types in Mongolian and Myanmar populations is largely unknown. We examined the expression of HPV in formalin-fixed and paraffin-embedded cervical tissues from 40 Japanese, 32 Mongolian, and 30 Myanmar cervical cancer patients. We performed immunohistochemistry using anti-HPV16 and anti-HPV 1, 6, 11, 16, 18 and 31 cocktail and then correlated it with the expression of Ki-67 and p63. HPV 16 was detected in 72%, 65% and 50% of Japanese, Mongolian and Myanmar cervical cancer patients, respectively, whereas 5 (13%) of the 40 patients, 8 (25%) of the 32 patients and 7 (23%) of the 30 patients in HPV 16-negative cancers were positive for other HPV types included in the cocktail, respectively. Ki-67 labeling index (LI) as well as p63 LI was significantly higher in HPV 16-positive patients than in HPV 16-negative ones in the Japanese and Mongolian samples. p63 expression was significantly associated with stage III and IV in Japan and Mongolia. These findings suggest that HPV 16 may be associated with cell proliferative activity and tumor progression, possibly depending upon the expression of p63 in the cervical cancer. In addition, immunohistochemical detection for distinguishing the type of HPV may also be useful for cervical cancer in the clinical setting.

Keywords: HPV; Japan; Mongolia; Myanmar; cervical cancer.

Fig. 1

HPV 16 localization in normal cervix, cervical intraepithelial neoplasia (CIN) I, III, SCC and ACC. (A) HPV 16 was not expressed in normal cervix, whereas (B–E) HPV 16 (arrows) was localized in the nuclei and cytoplasm of squamous epithelial cells in CIN I and CIN III and cancer cells of SCC and ACC.

Fig. 2

(A) HPV-type specific distribution among cervical cancer in samples from Japan, Mongolia, and Myanmar. Black bar; HPV 16 positive cases (%), gray bar; HPV cocktail positive cases (%), white bar; HPV negative cases (%). (B) Distribution of HPV 16 in SCC and ACC.

Fig. 2

(A) HPV-type specific distribution among cervical cancer in samples from Japan, Mongolia, and Myanmar. Black bar; HPV 16 positive cases (%), gray bar; HPV cocktail positive cases (%), white bar; HPV negative cases (%). (B) Distribution of HPV 16 in SCC and ACC.

Fig. 3

Ki-67 and p63 localization in normal cervix, cervical intraepithelial neoplasia (CIN) I and III. (A–C) In normal cervix, Ki-67 was localized in parabasal cells. In CIN I to III, Ki-67 expression spread from parabasal layer to the superficial layer. (D–F) p63 staining in normal cervix, CIN I and CIN III. In normal cervix, p63 was localized in the nuclei of basal and parabasal cells. In CIN I to III, p63 was spread from basal layer to the surface epithelium. Arrows indicate positive cells for Ki-67 and p63 in normal cervix, CIN I and CIN III. Bar=20 µm.

Fig. 4

A and C: Localization of HPV 16; B: HPV cocktail; D–F: Ki-67 and G–I: p63 in cervical cancer. (A, D and G) The panels were obtained from large cell keratinizing SCC, (B, E and H) from large cell non-keratinizing SCC and (C, F and I) ACC of each adjacent sections. (D, G, E and H) Ki-67 and p63-positive cells were abundant in SCC; however, (I) p63 was negative in ACC. (A and D, B and E) HPV 16 and HPV cocktail were co-expressed with Ki-67 in SCC. Arrows indicate positive cells for HPV 16, Ki-67 and p63 in cervical cancer. Bar=20 µm.

Fig. 5

Double immunostaining for HPV 16 and p63 in SCC. (A–C) Arrows indicate positive cells for HPV 16 and p63 in SCC. (C) HPV 16 immunoreactivity is detectable in most of the p63-positive nuclei. Bar=20 µm.

Fig. 6

Colocalization of p63 and Ki-67 in normal cervix and SCC by immunofluorescent staining. (A) p63 and Ki-67 were colocalized in some parabasal and basal epithelial cells of normal cervix and are visualized as white nuclei in the merged image. (B) p63 and Ki-67 were extensively colocalized (white nuclei) in merged image of SCC. Nuclei were counterstained with DAPI. Arrows indicate positive cells for p63, Ki-67 and DAPI in normal cervix and SCC. Bar=20 µm. (C) Correlation between percentage of p63-positive cells and Ki-67 labeling index (LI) in HPV 16-positive SCC (r=0.618, p=0.0005).