The Value of Tumor Treating Fields in Glioblastoma

The PI3K Inhibitor XH30 Enhances Response to Temozolomide in Drug-Resistant Glioblastoma via the Noncanonical Hedgehog Signaling Pathway

Glioblastoma multiforme (GBM) is the most common malignant tumor of the central nervous system. Temozolomide (TMZ)-based adjuvant treatment has improved overall survival, but clinical outcomes remain poor; TMZ resistance is one of the main reasons for this. Here, we report a new phosphatidylinositide 3-kinase inhibitor, XH30; this study aimed to assess the antitumor activity of this compound against TMZ-resistant GBM. XH30 inhibited cell proliferation in TMZ-resistant GBM cells (U251/TMZ and T98G) and induced cell cycle arrest in the G1 phase. In an orthotopic mouse model, XH30 suppressed TMZ-resistant tumor growth. XH30 was also shown to enhance TMZ cytotoxicity both in vitro and in vivo. Mechanistically, the synergistic effect of XH30 may be attributed to its repression of the key transcription factor GLI1 via the noncanonical hedgehog signaling pathway. XH30 reversed sonic hedgehog-triggered GLI1 activation and decreased GLI1 activation by insulin-like growth factor 1 via the noncanonical hedgehog signaling pathway. These results indicate that XH30 may represent a novel therapeutic option for TMZ-resistant GBM.

Tumor-Treating Fields: A fourth modality in cancer treatment, new practice updates

Although major innovations in treatment are advancing, cancer persists as one of the leading causes of mortality. With the rising incidence of cancer and as we treat them, patients incur short term and long-term toxicities of current traditional therapies, including chemotherapy. This imposes a significant physical, emotional, and financial burden among patients, which affects their quality of life. Tumor-Treating Fields (TTFields) is a novel innovative new treatment modality that utilizes alternating electric fields at specific intermediate frequencies to diminish tumor growth by inhibiting mitosis and thus proliferation of malignant cells. The distinguishing feature of this new treatment modality is that it is noninvasive and tolerable. In fact, TTFields is currently FDA approved for the treatment of glioblastoma multiforme (GBM) as well as malignant pleural mesothelioma (MPM). Recently, TTFields have also been found to affect immunogenic cell death resulting in stronger anti-neoplastic effects. In this review, we discuss the mechanism of action of TTFields, the plethora of clinical trials being conducted in patients with GBM, pancreatic adenocarcinoma, ovarian cancer, non-small-cell-lung-cancer (NSCLC), brain metastasis from NSCLC, and MPM and toxicity profile.

Mechanisms involved in the anti-tumor effects of Toosendanin in glioma cells

BACKGROUND

Toosendanin (TSN) is a triterpenoid compound mainly used as an ascaris repellant. Recent studies have shown that it possesses antitumor effects in many types of tumor cells. However, the effects of TSN on glioma cells have rarely been reported.

METHODS

Different assays were performed to investigate the effects of TSN on the different glioma cell lines including U87MG and LN18. The assays included colony formation, wound healing, and transwell assays. Furthermore, Hoechst 33342 staining, flow cytometry, and western blotting analysis were performed to investigate the apoptotic activities of TSN. Finally, the results were confirmed using a xenograft tumor model that comprised of nude mice.

RESULTS

In vitro, the CCK-8 and colony formation assays showed that TSN effectively inhibited glioma cell proliferation. Moreover, the inhibitory effects on glioma cell migration and invasion were demonstrated through the wound healing and transwell assays, respectively. Hoechst 33342 staining, flow cytometry, and western blotting assays demonstrated the significant effect of TSN in the apoptosis induction of glioma cells. Furthermore, the anti-glioma effect of TSN was exerted through the inhibition of the PI3K/Akt/mTOR signaling pathways as demonstrated by western blotting analysis. In addition, the effects of TSN on glioma cell viability, apoptosis, cell cycle arrest, migration, and invasion were reversed by 740Y-P, a PI3K activator. Finally, the mouse xenograft model confirmed the suppressive effect of TSN on tumor growth in vivo.

CONCLUSION

Our results suggest that TSN is a promising chemotherapeutic drug for patients with glioma.

Therapy of pancreatic cancer with alternating electric fields: Limitations of the method

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant tumor with a poor prognosis. More effective treatment options are urgently needed. The use of physical and weak alternating electric fields (TTFields) can inhibit cell division of PDAC carcinoma and is currently being investigated in clinical trials. Here, we analyzed this new physical treatment under non-ideal conditions such as may occur during patient treatment. Three established human PDAC cell lines BxPC-3, gemcitabine-resistant BxPC-3 (BxGem), AsPC-1, and a non-malignant primary pancreatic cell line CRL-4023 were treated with TTFields in vitro. MTT assays, electrical impedance measurement, cell staining with Annexin V/7AAD followed by FACS analysis, digital image analysis and immunohistochemistry were performed. Treatment with TTFields smaller than 0.7 V/cm and field lines in the direction of mitotic spindle orientation significantly inhibited proliferation of all PDAC cells at 150 kHz, but significantly increased viability of AsPC-1 cells at all frequencies between 100 kHz and 300 kHz and that of BxPC-3 and BxGem cells at 250 kHz. Apoptosis or necrosis were not induced. Non-malignant CRL-4023 cells were not affected at 150 kHz. TTFields damaged PDAC cell lines but even favored their viability at very weak field strength and unfavorable frequency or inadequate field direction.

Observations on the anti-glioma potential of electrical fields: is there a role for surgical neuromodulation?

Alternating electrical field therapy represents a recent addition to the armamentarium against high grade glioma. Randomised trial evidence suggests a survival benefit from adjunctive scalp delivered Tumour Treating Fields (TTFields) in glioblastoma. Any underlying anti-glioma effect is not fully understood, but interference with cell division and microtubule assembly has been averred. The survival benefit claimed for TTFields is modest and is associated with mild reductions in health-related quality of life indices amid costs that presently preclude routine use. I review possible mechanisms by which alternating electrical fields may confer an anti-glioma effect. As scalp and skull are poor conductors of an electrical field, a case is made here for implantable electrodes, perhaps placed at the time of tumour debulking. Such a system may deliver an electrical field directly to the tumour resection cavity and with greater precision.