Severe acute rhabdomyolysis induced by multi-agent chemotherapy for alveolar rhabdomyosarcoma in a 15-year-old female: a case report

Metabolic aspects of glycogenolysis with special attention to McArdle disease

The physiological function of muscle glycogen is to meet the energy demands of muscle contraction. The breakdown of glycogen occurs through two distinct pathways, primarily cytosolic and partially lysosomal. To obtain the necessary energy for their function, skeletal muscles utilise also fatty acids in the β-oxidation. Ketogenesis is an alternative metabolic pathway for fatty acids, which provides an energy source during fasting and starvation. Diseases arising from impaired glycogenolysis lead to muscle weakness and dysfunction. Here, we focused on the lack of muscle glycogen phosphorylase (PYGM), a rate-limiting enzyme for glycogenolysis in skeletal muscles, which leads to McArdle disease. Metabolic myopathies represent a group of genetic disorders characterised by the limited ability of skeletal muscles to generate energy. Here, we discuss the metabolic aspects of glycogenosis with a focus on McArdle disease, offering insights into its pathophysiology. Glycogen accumulation may influence the muscle metabolic dynamics in different ways. We emphasize that a proper treatment approach for such diseases requires addressing three important and interrelated aspects, which include: symptom relief therapy, elimination of the cause of the disease (lack of a functional enzyme) and effective and early diagnosis.

Case Report: Etoposide-nedaplatin induced rhabdomyolysis in a small cell lung cancer patient

Rhabdomyolysis syndrome refers to the breakdown and necrosis of muscle tissue due to various reasons and caused by the release of intracellular contents into the blood stream, which can lead to acute renal failure or even death. In this article, we describe for the first time a case report of severe rhabdomyolysis induced by etoposide-nedaplatin chemotherapy in a small cell lung cancer (SCLC IIIb) patient. The patient developed progressive general muscle pain and weakness after the first cycle of chemotherapy, accompanied by elevated creatine kinase (CK), myoglobin (Mb), alanine aminotransferase (ALT), spartate aminotransferase (AST), and lactate dehydrogenase (LDH). Examination of and inquiry regarding the medical history were used to exclude various factors of rhabdomyolysis caused by trauma, strenuous activities, infections, drugs, hyperthermia, and immunity; the patient was diagnosed with severe rhabdomyolysis induced by chemotherapy. After treatment with intravenous fluids and methylprednisolone, the patient's symptoms were relieved and laboratory results were significantly improved. An unexpected situation arose, in that the lung CT scan showed that the lung mass was significantly smaller than that before chemotherapy; the reason for this is not clear. Rhabdomyolysis induced by anti-cancer drugs, especially chemotherapy drugs, is rarely reported and easily overlooked. Therefore, physicians should be aware of this rare but potentially serious complication when using chemotherapy drugs.

GLI inhibitor GANT-61 diminishes embryonal and alveolar rhabdomyosarcoma growth by inhibiting Shh/AKT-mTOR axis

Rhabdomyosarcoma (RMS) typically arises from skeletal muscle. Currently, RMS in patients with recurrent and metastatic disease have no successful treatment. The molecular pathogenesis of RMS varies based on cancer sub-types. Some embryonal RMS but not other sub-types are driven by sonic hedgehog (Shh) signaling pathway. However, Shh pathway inhibitors particularly smoothened inhibitors are not highly effective in animals. Here, we show that Shh pathway effectors GLI1 and/or GLI2 are over-expressed in the majority of RMS cells and that GANT-61, a specific GLI1/2 inhibitor dampens the proliferation of both embryonal and alveolar RMS cells-derived xenograft tumors thereby blocking their growth. As compared to vehicle-treated control, about 50% tumor growth inhibition occurs in mice receiving GANT-61 treatment. The proliferation inhibition was associated with slowing of cell cycle progression which was mediated by the reduced expression of cyclins D1/2/3 & E and the concomitant induction of p21. GANT-61 not only reduced expression of GLI1/2 in these RMS but also significantly diminished AKT/mTOR signaling. The therapeutic action of GANT-61 was significantly augmented when combined with chemotherapeutic agents employed for RMS therapy such as temsirolimus or vincristine. Finally, reduced expression of proteins driving epithelial mesenchymal transition (EMT) characterized the residual tumors.