Corrigendum: A Novel Role of Connexin 40-Formed Channels in the Enhanced Efficacy of Photodynamic Therapy.

[This corrects the article DOI: 10.3389/fonc.2019.00595.].

A Novel Role of Connexin 40-Formed Channels in the Enhanced Efficacy of Photodynamic Therapy.

Despite responses to initial treatment of photodynamic therapy (PDT) being promising, a recurrence rate exists. Thus, finding novel therapeutic targets to enhance PDT efficacy is an urgent need. Reports indicate that connexin (Cx) 40 plays an important role in tumor angiogenesis and growth. However, it is unknown whether Cx40-composed channels have effects on PDT efficacy. The study uniquely demonstrated that Cx40-formed channels could enhance the phototoxicity of PDT to malignant cells in vitro and in vivo. Specifically, Cx40-formed channels at high cell density could increase PDT photocytotoxicity. This action was substantially restricted when Cx40 expression was not induced or Cx40 channels were restrained. Additionally, the presence of Cx40-composed channels enhanced the phototoxicity of PDT in the tumor xenografts. The above results indicate that enhancing the function of Cx40-formed channels increases PDT efficacy. The enhancement of PDT efficacy mediated by Cx40 channels was related with intracellular pathways mediated by ROS and calcium pathways, but not the lipid peroxide-mediated pathway. This work demonstrates the capacity of Cx40-mediated channels to increase PDT efficacy and suggests that therapeutic strategies designed to maintain or enhance Cx40 expression and/or channels composed by Cx40 may increase the therapeutic efficacy of PDT.

A novel role of Cx43-composed GJIC in PDT phototoxicity: an implication of Cx43 for the enhancement of PDT efficacy.

In spite of initially promising responses, 5-year recurrence after photodynamic therapy (PDT) sustains high level and an increase in PDT effectiveness is needed. It has been demonstrated that gap junctional intercellular communication (GJIC) formed by Connexin (Cx)43 could improve the transfer of "death signal" between cells, thereby causing the enhancement of cytotoxicity of chemotherapeutics and suicide gene therapy. Nevertheless, whether Cx43-composed GJIC has an effect on PDT phototoxicity remains unknown. This study showed that Cx43-formed GJIC could improve PDT phototoxicity to tumor cells in vitro and in vivo. Specifically, Cx43-formed GJIC under the condition of high cellular density could improve PDT phototoxicity in Cx43-transfected HeLa cells and Cx43-expressing U87 glioma cells. This effect was remarkably inhibited when Cx43 was not expressed or Cx43-formed GJ channels were prohibited. Additionally, the presence of Cx43-mediated GJIC could decrease the mean RTV and tumor weights of xenografts after Photofrin-PDT. The improved PDT efficacy by Cx43-composed GJIC was correlated with stress signaling pathways mediated by ROS, calcium and lipid peroxide. The present study demonstrates the presence of Cx43-composed GJIC improves PDT phototoxicity and suggests that therapeutic strategies designed to upregulate the expression of Cx43 or enhance Cx43-mediated GJIC function may increase the sensitivity of malignant cell to PDT, leading to the increment of PDT efficacy. Oppositely, factors that retard Cx43 expression or prohibit the function of Cx43-mediated GJIC may cause insensitivity of malignant cells to PDT, leading to PDT resistance.

Effect of low frequency ultrasound thawing method on the quality characteristics of Peru squid ( Dosidicus gigas).

The effects of different thawing methods (air thawing, water soak thawing, refrigeration thawing, low frequency ultrasound thawing at 160, 240, 320 and 400 W) on thawing time, thawing loss, cooking loss, water-holding capacity and texture of frozen squid were investigated. The results showed that thawing loss and thawing time were reduced significantly ( p < 0.05) by ultrasound thawing compared with the water soak thawing and air thawing, but the cooking loss had no significant difference ( p > 0.05). Results of the ultrasound thawing especially at 160 and 240 W on microstructure showed less destructive effect on muscle. The microstructure of the muscle was destroyed significantly after air thawing and water soak thawing compared with the ultrasound thawing, which showed that more fibre structure was broken and the gap between the muscle fibres was increased significantly. Low-field NMR results showed that the ability of immobile water shifting to free water after ultrasound thawing was lower than air thawing and water soak thawing, which was consistent with the results of thawing loss and cooking loss. Ultrasound thawing might be chosen as an alternative method to enhance the quality during thawing process.

Oridonin inhibits mTOR signaling and the growth of lung cancer tumors.

Oridonin, an active diterpenoid isolated from Rabdosia rubescens, has been widely used for treatment of various types of cancer. It has been shown that oridonin produced an antiproliferative effect in a lung cancer cell line in vitro. However, the antitumor effects of oridonin in lung cancer cells xenograft mice were poorly understood. The aim of the current study was to investigate the antitumor activity of oridonin in vivo and the molecular mechanisms mediating this antitumor efficacy. The human A549 and NCI-H292 non-small cell lung cancer cell lines were transferred to nude mice for the establishment of xenograft models. The results showed that oridonin (10, 20, 40 mg/kg, intraperitoneally) treatment for 28 days significantly decreased tumor volume and induced tumor growth inhibition in both A549 and NCI-H292 xenograft mice. Furthermore, oridonin promoted apoptosis by increasing terminal dUTP nick end labeling-positive cells as well as the ratio of Bax/Bcl-2 in xenograft mice. In addition, chronic oridonin administration inhibited mammalian target of rapamycin (mTORC1) activity by reduction of p-mTOR and p-p70s6k levels, suggesting that the increased apoptosis triggered by oridonin administration was associated with the downregulation of mTORC1 activity. Moreover, inhibition of mTORC1 by rapamycin (2 mg/kg, intraperitoneally) enhanced the anticancer activity of oridonin in mice xenograft models. These findings indicate that treatment with oridonin exhibited antitumor actions through induction of apoptotic response by inhibition of mTORC1 function. Our results also proposed the potential that inhibition of mTORC1 might be an effective target for increasing the therapeutic outcome in lung cancer patients treated with oridonin.