This study examined the role of the immuno­suppressive enzyme indoleamine-2,3-dioxygenase (IDO) in ovarian cancer progression, and the possible application of this enzyme as a target for ovarian cancer therapy. We transfected a short hairpin RNA vector targeting IDO into the human ovarian cancer cell line SKOV-3, that constitutively expresses IDO and established an IDO downregulated cell line (SKOV-3/shIDO) to determine whether inhibition of IDO mediates the progression of ovarian cancer. IDO downregulation suppressed tumor growth and peritoneal dissemination in vivo, without influencing cancer cell growth. Moreover, IDO downregulation enhanced the sensitivity of cancer cells to natural killer (NK) cells in vitro, and promoted NK cell accumulation in the tumor stroma in vivo. These findings indicate that downregulation of IDO controls ovarian cancer progression by activating NK cells, suggesting IDO targeting as a potential therapy for ovarian cancer.

High‑risk human papillomavirus (HPV) is a common cause of cervical cancer. HPV E6 oncoprotein promotes the degradation of host tumor suppressor gene p53, leading to the development of tumors. Therapeutic strategies that specifically target E6, which is constitutively expressed in tumors and is not present in normal tissues, may be highly effective and safe. CRISPR‑CRISPR associated protein 9 (Cas9) is one of the genome editing technologies that has recently garnered attention, and is used to knockout target gene expression. By combining cervical cancer cell lines engineered to constitutively express Cas9 and an adeno‑associated virus (AAV) vector carrying a single guide (sg) RNA targeting E6 (AAV‑sgE6), the present study sought to investigate the effects of this novel therapeutic approach on cervical cancer. The Cas9 gene was transfected into three high‑risk HPV‑positive cervical cancer cell lines (HeLa, HCS‑2, and SKG‑I) to establish cell lines that constitutively expressed Cas9. Using these cell lines, genetic mutations and their frequencies, as well as the levels of protein expression, apoptosis and cell proliferation were examined in vitro. In addition, the effects of AAV‑sgE6 were examined in a mouse model of cervical cancer in vivo by a single administration of AAV‑sgE6 directly into subcutaneous tumors. The results demonstrated that multiple mutations occurred frequently in the targeted E6 genomic sequence in cervical cancer cells transduced with AAV‑sgE6. In addition, these AAV‑sgE6‑transduced cells had reduced expression of E6, increased expression of p53, increased apoptosis and their growth was suppressed in a concentration‑dependent manner. Furthermore, subcutaneous tumor growth was significantly suppressed in vivo following intratumoral administration of AAV‑sgE6, and adverse events due to AAV‑sgE6 administration were not observed. Collectively, the present results indicated that targeting E6 expression in high‑risk HPV by CRISPR‑Cas9 is a highly specific and effective strategy that may be effective in treating patients with cervical cancer.

Ovarian clear cell adenocarcinoma has low sensitivity to platinum drugs. The molecular-biological mechanism of the low sensitivity has not been clarified. The objective of this study was to identify candidate genes associated with low sensitivity of clear cell adenocarcinoma to platinum drugs. Exhaustive gene profiling of 4 ovarian clear cell adenocarcinoma cell lines, KK, OVMANA, OVSAYO, and RMG-1 and 4 ovarian serous adenocarcinoma cell lines, KF, HRA, SHIN-3 and KOC-2S was performed by DNA microarray. Obtained candidate genes were suppressed by RNA interference and changes in the cisplatin sensitivity of clear cell adenocarcinoma cells were observed. Six genes including the glutathione peroxidase 3 (GPX3) gene were identified to be highly expressed in clear cell adenocarcinoma by DNA microarray analysis. GPX3 suppression by RNA interference increased cisplatin sensitivity 3.3-4.2-fold in 3 of the 4 clear cell adenocarcinoma cell lines. GPX3 was identified to be a gene highly expressed in clear cell adenocarcinoma. Since GPX3 suppression increased the cisplatin sensitivity of clear cell adenocarcinoma cells, GPX3 may be a candidate gene associated with the low cisplatin sensitivity of clear cell adenocarcinoma.

Vasohibin-2 (VASH2) is a homolog of vasohibin-1 and exhibits pro-angiogenic activity. We recently reported that VASH2 is expressed in certain ovarian cancers and promotes tumor growth through angiogenesis. To further demonstrate the effectiveness of molecular targeting of VASH2 for anticancer treatment, we applied in vivo delivery of siRNA targeting VASH2 (siVASH2) using atelocollagen to a xenograft model of ovarian cancer. We inoculated mice s.c. with DISS and SKOV-3, two representative human ovarian serous adenocarcinoma cell lines. When tumors were measurable, we initiated treatment with control or siVASH2 mixed with atelocollagen, which enveloped the whole tumor. Treatment with siVASH2 significantly inhibited s.c. tumor growth by abrogating tumor angiogenesis. We confirmed that expression of VASH2 mRNA in the tumor was downregulated by siVASH2 treatment. In addition, the siVASH2-treated tumor contained more blood vessels covered with pericytes, indicating that knockdown of VASH2 contributes to the normalization of tumor blood vessels. Based on these results, VASH2 may be a promising molecular target for ovarian cancer treatment.

This study examined the role of the immunosuppressive enzyme indoleamine-2,3-dioxygenase (IDO) in cervical cancer progression and the possible use of this enzyme for cervical cancer therapy. We analyzed IDO protein expression in 9 cervical cancer cell lines (SKG-I, -II, -IIIa, -IIIb, SiHa, CaSki, BOKU, HCS-2 and ME-180) stimulated with interferon-γ. IDO expression was observed in all cell lines except for SKG-IIIb. We transfected the human cervical cancer cell line CaSki that constitutively expresses IDO with a short hairpin RNA vector targeting IDO, and established an IDO-downregulated cell line to determine whether inhibition of IDO mediates cervical cancer progression. IDO downregul­ation suppressed tumor growth in vivo, without influencing cancer cell growth in vitro. Moreover, IDO downregulation enhanced the sensitivity of cervical cancer cells to natural killer (NK) cells in vitro and promoted NK cell accumul­ation in the tumor stroma in vivo. These findings indicate that downregulation of IDO controls cervical cancer progression by activating NK cells, suggesting IDO as a potential therapy for cervical cancer.