The exosome-mediated autocrine and paracrine actions of plasma gelsolin in ovarian cancer chemoresistance.

Ovarian cancer (OVCA) is the most lethal gynecological cancer, due predominantly to late presentation, high recurrence rate and common chemoresistance development. The expression of the actin-associated protein cytosolic gelsolin (GSN) regulates the gynecological cancer cell fate resulting in dysregulation in chemosensitivity. In this study, we report that elevated expression of plasma gelsolin (pGSN), a secreted isoform of GSN and expressed from the same GSN gene, correlates with poorer overall survival and relapse-free survival in patients with OVCA. In addition, it is highly expressed and secreted in chemoresistant OVCA cells than its chemosensitive counterparts. pGSN, secreted and transported via exosomes (Ex-pGSN), upregulates HIF1α-mediated pGSN expression in chemoresistant OVCA cells in an autocrine manner as well as confers cisplatin resistance in otherwise chemosensitive OVCA cells. These findings support our hypothesis that exosomal pGSN promotes OVCA cell survival through both autocrine and paracrine mechanisms that transform chemosensitive cells to resistant counterparts. Specifically, pGSN transported via exosomes is a determinant of chemoresistance in OVCA.

Neobalantidium coli: First molecular identification from the Eurasian wild boar, Sus Scrofa in Bushehr Province, Southwestern Iran.

Balantidium coli is a common parasite of pig and wild boars (Sus scrofa) which can infect humans and several species of mammals. This study aimed to determine the genotype of Balantidium isolated from Eurasian wild boars in Bushehr province, Southwestern Iran. Twenty-five faecal samples, originating from 25 wild boars captivated in our previous study, were processed. DNA was extracted from the faecal samples and PCR-amplified, targeting an ITS1-5.8s-rRNA-ITS2 region of Balantidium genome. PCR product was purified from the gel, and sequenced. BLAST analysis was performed in order to compare our isolates with other previously reported ones. A phylogenetic tree was constructed, using MegaX software, to find out the phylogenetic diversity of the isolates. With PCR it was possible to detect Balantidium DNA in the faecal samples of 13 out of 25 (52%) of the wild boars. BLAST analysis of seven isolates revealed that the isolates belong to the newly introduced genus Neobalantidium coli. Sequences of three isolates were deposited in the GenBank. Moreover, molecular analysis revealed six areas of nucleotide differences within the isolates and nine areas of difference between the sequences obtained in this study and those available in the GenBank. Phylogenetic analysis revealed that the sequences of isolates of this study have up to 2.2% dissimilarity from those published in the GenBank. The findings of this study, for the first time, revealed that some of the isolates of Balantidium originating from wild boars in Southwestern Iran belonged to the N. coli.

Cell fate regulation by gelsolin in human gynecologic cancers.

Chemoresistance is a major hurdle in cancer treatment. Down-regulation of apoptosis pathways is one of the key determinants for chemoresistance. Here, we report higher gelsolin (GSN) levels in chemoresistant gynecological cancer cells compared with their sensitive counterparts. cis-Diammine dichloroplatinium (II) (CDDP)-induced GSN down-regulation is associated with its cleavage and apoptosis. Although the C-terminal GSN fragment (C-GSN) sensitized chemoresistant cells to CDDP, intact GSN and its N-terminal fragment (N-GSN) attenuated this response. GSN silencing also facilitated CDDP-induced apoptosis in chemoresistant cells. In contrast, intact GSN (I-GSN) was prosurvival in the presence of CDDP through a FLICE-like inhibitory protein (FLIP)-Itch interaction. This interaction was colocalized in the perinuclear region that could be dissociated by CDDP in sensitive cells, thereby inducing FLIP ubiquitination and degradation, followed by apoptosis. In resistant cells, GSN was highly expressed and CDDP failed to abolish the I-GSN-FLIP-Itch interaction, resulting in the dysregulation of the downstream responses. In addition, we investigated the association between GSN expression in ovarian serous adenocarcinoma and progression free survival and overall survival, as well as clinical prognosis. GSN overexpression was significantly associated with more aggressive behavior and more cancer deaths and supported our hypothesis that high GSN expression confers chemoresistance in cancer cells by altering the GSN-FLIP-Itch interaction. These findings are in agreement with the notion that GSN plays an important role in the regulation of gynecological cell fate as reflected in dysregulation in chemosensitivity.

Gelsolin regulates cisplatin sensitivity in human head-and-neck cancer.

Chemoresistance is a major challenge in cancer therapy. Cisplatin is commonly used for chemotherapy in patients with head-and-neck cancer (HNC), but it increases control of the disease by only 10-15%. Downregulation of proapoptotic pathways is a key determinant for chemoresistance in which gelsolin (GSN) is critically involved. We analyzed the association between GSN expression and cisplatin resistance in HNC cell lines, animals with HNC and cancer tissue samples from 58 cisplatin-treated patients with HNC. GSN expression levels were positively associated with chemoresistance in vitro and in vivo. Cisplatin-induced GSN downregulation was associated with the cleavage of GSN and the promotion of apoptosis. GSN silencing facilitated cisplatin-induced apoptosis in chemoresistant cells. In contrast, intact gelsolin was prosurvival in the presence of cisplatin by interacting with X-linked inhibitor of apoptosis protein (XIAP). In chemosensitive cells, cisplatin suppressed GSN-XIAP interaction, promoted translocation of XIAP from the perinuclear region to the nucleus and induced apoptosis. In chemoresistant cells, GSN was highly expressed, and cisplatin had no significant effect on GSN-XIAP interaction and apoptosis. We conclude that GSN is important for chemoresistance in HNC and may be an appropriate therapeutic target in chemoresistant cancers.

Cisplatin induces p53-dependent FLICE-like inhibitory protein ubiquitination in ovarian cancer cells.

Understanding the mechanism of cisplatin (CDDP) action may improve therapeutic strategy for ovarian cancer. Although p53 and FLICE-like inhibitory protein (FLIP) are determinants of CDDP sensitivity in ovarian cancer, the interaction between p53 and FLIP remains poorly understood. Here, using two chemosensitive ovarian cancer cell lines and various molecular and cellular approaches, we show that CDDP induces p53-dependent FLIP ubiquitination and degradation, and apoptosis in vitro. Moreover, we showed that Itch (an E3 ligase) forms a complex with FLIP and p53 upon CDDP treatment. These results suggest that p53 facilitates FLIP down-regulation by CDDP-induced FLIP ubiquitination and proteasomal degradation.

Possible role of FLICE-like inhibitory protein (FLIP) in chemoresistant ovarian cancer cells in vitro.

Chemoresistance is a major therapeutic problem and the current knowledge on cellular mechanisms involved is incomplete. In the present study, we have investigated the possible involvement of Fas-associated death domain-like interleukin-1beta-converting enzyme (FLICE)-like inhibitory protein (FLIP) in ovarian cancer resistance by comparing chemosensitive (OV2008) and chemoresistant (C13*) ovarian cancer cells treated with cisplatin in vitro, and/or transfected with FLIP sense cDNA or FLIP small interfering RNA (siRNA) and determining FLIP protein content, cleavage of caspase-8 and caspase-3 and apoptosis. Cisplatin significantly decreased FLIP protein level, induced cleavage of caspase-8 and caspase-3 and apoptosis in a concentration-dependent manner in cisplatin-sensitive but not -resistant cells. While overexpression of FLIP-attenuated cisplatin-induced cleavage of caspase-8 and caspase-3 and apoptosis in chemosensitive cells, downregulation of FLIP in chemoresistant cells by siRNA increased apoptosis induced by cisplatin. These results suggest that FLIP plays a significant role in the regulation of apoptosis in human ovarian cancer cells and their sensitivity to cisplatin. This cell survival factor may be an important determinant in chemoresistance in ovarian cancer and may serve as a molecular target for the development of novel therapy for chemoresistant ovarian cancer.