Magnetic field (MF) is being used in antitumor treatment; however, the underlying biological mechanisms remain unclear. In this study, the potency and mechanism of a previously published tumor suppressing MF exposure protocol were further investigated. This protocol, characterized as a 50 Hz electromagnetic field modulated by static MF with time-average intensity of 5.1 mT, when applied for 2 h daily for over 3 consecutive days, selectively inhibited the growth of a broad spectrum of tumor cell lines including lung cancer, gastric cancer, pancreatic cancer and nephroblastoma. The level of intracellular reactive oxygen species (ROS) increased shortly after field exposure and persisted. Subsequently, pronounced DNA damage and activation of DNA repair pathways were identified both in vitro and in vivo. Furthermore, use of free radical scavenger alleviated DNA damage and partially reduced cell death. Finally, this field was found to inhibit cell proliferation, and simultaneously induced two types of programmed cell death, apoptosis and ferroptosis. In conclusion, this tumor suppressing MF could determine cell fate through ROS-induced DNA damage, inducing oxidative stress and activation of the DNA damage repair pathways, eventually lead to apoptosis and ferroptosis, as well as inhibition of tumor growth.

Progressive pseudorheumatoid dysplasia (PPD) is characterized by continuous degeneration and loss of articular cartilage, which has been attributed to mutations in the gene encoding WISP3. We collected a PPD family and analyzed their WISP3 genes mutation. Articular chondrocytes (ACs) were purified from the femurs of a PPD patient after hip replacement surgery. Cell growth, proliferation, and viability were examined. Gene expression profiling and analyses of matrix metalloproteinases (MMP)-1, -3, and -13 proteins were carried out using cDNA differential microarrays, real-time reverse transcriptase-polymerase chain reaction (RT-PCR), immunohistochemistry, and Western blot analysis. We found that two probands carried a deletion (840delT) mutation in maternal allele, which leads to truncated WISP3 protein missing 43 residues in C terminus; and a 1000T>C substitution in paternal allele, which was also passed on to four other members in the PPD kindred. PPD ACs were heterogeneous in size with an enhanced rate of cell proliferation and viability compared with the normal ACs. MMP-1, -3, and -13 mRNA expressions were dereased in PPD ACs. MMP-1, -3, and -13 protein levels, however, were increased in cell lysates from PPD ACs, but markedly decreased in the supernatants from cultured ACs. WISP3 mRNA expression in PPD ACs was also decreased. Our results show, for the first time, a compound heterozygous mutation of WISP3 and a series of cellular and molecular changes disturbing the endochondral ossification in this PPD patient.

Certain magnetic fields (MF) have potential therapeutic antitumor effect whereas the underlying mechanism remains undefined. In this study, a well-characterized MF was applied to two common childhood malignancies, nephroblastoma and neuroblastoma. This MF has a time-averaged total intensity of 5.1 militesla (mT), and was generated as a superimposition of a static and an extremely low frequency (ELF) MF in 50 Hertz (Hz). In nephroblastoma and neuroblastoma cell lines including G401, CHLA255, and N2a, after MF exposure of 2 h per day, the cell viability decreased significantly after 2 days. After 3 days, inhibition rates of 17-22% were achieved in these cell lines. Furthermore, the inhibition rate was positively associated with exposure time. On the other hand, when using static MF only while maintaining the same time-averaged intensity of 5.1 mT, the inhibition rate was decreased. Thus, both time and combination of ELF field were positively associated with the inhibitory effect of this MF. Exposure to the field decreased cell proliferation and induced apoptosis. Combinational use of MF together with chemotherapeutics cisplatin (DDP) was performed in both in vitro and in vivo experiments. In cell lines, combinational treatment further increased the inhibition rate compared with single use of either DDP or MF. In G401 nephroblastoma tumor model in nude mice, combination of MF and DDP resulted in significant decrease of tumor mass, and the side effect was limited in mild liver injury. MF exposure by itself did not hamper liver or kidney functions. In summary, the antitumor effect of an established MF against neuroblastoma and nephroblastoma is reported, and this field has the potential to be used in combination with DDP to achieve increased efficacy and reduce side effects in these two childhood malignancies. Bioelectromagnetics. 39:375-385, 2018. © 2018 Wiley Periodicals, Inc.

The tuber of amorphophallus konjac (TuAK) is an antitumor herb used in traditional Chinese medicine. The present study investigated the inhibitory effect of TuAK against gastric cancer and the underlying mechanisms associated with two programmed cell death pathways, apoptosis and autophagy. TuAK was extracted by organic solvents including ethanol and ligarine. The extract of TuAK, shortened as TuAKe, significantly inhibited the growth of cultured gastric cancer cell lines SGC-7901 and AGS, with IC50 of 35-45 µg/ml. TuAKe could increase cell apoptosis and induce cell cycle arrest. For the apoptosis-associated proteins, expressions of survivin and Bcl-2 were decreased by treatment of TuAKe, and the expression of Bax and caspase-9 was increased. Furthermore, TuAKe could promote autophagy, and the antitumor efficacy of TuAKe was significantly hampered by targeted suppression of autophagy, suggesting that autophagy contributed to TuAKe-induced cell death. Furthermore, patients with gastric cancer who received TuAK-based medicinal decoction achieved improved scores in assessment of life quality compared with those without TuAK treatment. This study demonstrated the antitumor activity of TuAKe against gastric cancer, and is the first report to show that the underlying mechanism is associated with induction of autophagy. Our data provided support of the clinical use of amorphophallus konjac-based medication in combination with classical chemotherapy to achieve optimized outcome for gastric cancer.

Our results suggest that autophagy deregulation is involved in nephroblastoma, and targeting autophagy can serve as a potential adjuvant strategy for the highly malignant cases.