Gene Mutation May Lead to Treatment for Liver Cancer

Editor’s note: Cancer is caused by genetic mutations that lead to excess cell growth and tumor formation. Scientists have identified many specific cancer-causing mutations, and drugs have been developed to target and treat tumors with some of these specific mutations. Researchers recently discovered that two mutations—IDH1 and IDH2—can lead to the development of intrahepatic cholangiocarcinoma (iCCA). The discovery could open up new treatment options for some patients who have these mutations. Indeed, there are ongoing clinical trials testing new drugs in patients with IDH1 and IDH2 mutations.

“Two genetic mutations in liver cells may drive tumor formation in intrahepatic cholangiocarcinoma (iCCA), the second most common form of liver cancer, according to a research published in the July issue of the journal Nature.

“A team led by the Icahn School of Medicine at Mount Sinai and Harvard Medical School has discovered a link between the presence of two mutant proteins IDH1 and IDH2 and cancer. Past studies have found IDH mutations to be among the most common genetic differences seen in patients with iCCA, but how they contribute to cancer development was unknown going into the current effort.

“iCCA strikes bile ducts, tube-like structures in the liver that carry bile, which is required for the digestion of food. With so much still unknown about the disease, there is no first-line, standard of care and no successful therapies.

” ‘iCCA is resistant to standard treatments like chemotherapy and radiation,’ said Josep Maria Llovet, MD, Director of the Liver Cancer Program, Division of Medicine, Icahn School of Medicine at Mount Sinai, and contributing author. ‘Understanding the molecular mechanism of the disease is the key to finding a treatment that works.’ ”


Study Identifies Novel Genomic Changes in the Most Common Type of Lung Cancer; TCGA Finds Mutations in a Key Cancer-Causing Pathway, Expanding Targets for Existing Drugs

Editor’s note: Cancer is caused by genetic mutations that lead to excess cell growth and tumor formation. Scientists have identified many specific cancer-causing mutations, and drugs have been developed to target and treat tumors with some of these specific mutations. Researchers recently found mutations in lung adenocarcinoma tumors that they had not seen in that type of cancer before. The discovery could eventually lead to new treatment options for some patients who have these mutations.

“Researchers from The Cancer Genome Atlas (TCGA) Research Network have identified novel mutations in a well-known cancer-causing pathway in lung adenocarcinoma, the most common subtype of lung cancer. Knowledge of these genomic changes may expand the number of possible therapeutic targets for this disease and potentially identify a greater number of patients with treatable mutations because many potent cancer drugs that target these mutations already exist.

“TCGA is jointly funded and managed by the National Cancer Institute (NCI) and the National Human Genome Research Institute (NHGRI), both part of the National Institutes of Health. A TCGA analysis of another, less common, form of lung cancer, squamous cell carcinoma, was reported in 2012.

“In this new study, published online July 9, 2014, in the journal Nature, researchers examined the genomes, RNA, and some protein from 230 lung adenocarcinoma samples. In three-quarters of the samples, the scientists ultimately identified mutations that put a cell signaling pathway known as the RTK/RAS/RAF pathway into overdrive.”


Cancer Cell – Transformation-Associated Changes in Sphingolipid Metabolism Sensitize Cells to Lysosomal Cell Death Induced by Inhibitors of Acid Sphingomyelinase

“Lysosomal membrane permeabilization and subsequent cell death may prove useful in cancer treatment, provided that cancer cell lysosomes can be specifically targeted. Here, we identify acid sphingomyelinase (ASM) inhibition as a selective means to destabilize cancer cell lysosomes. Lysosome-destabilizing experimental anticancer agent siramesine inhibits ASM by interfering with the binding of ASM to its essential lysosomal cofactor, bis(monoacylglycero)phosphate. Like siramesine, several clinically relevant ASM inhibitors trigger cancer-specific lysosomal cell death, reduce tumor growth in vivo, and revert multidrug resistance. Their cancer selectivity is associated with transformation-associated reduction in ASM expression and subsequent failure to maintain sphingomyelin hydrolysis during drug exposure. Taken together, these data identify ASM as an attractive target for cancer therapy.”


Cancer Cell – Transformation-Associated Changes in Sphingolipid Metabolism Sensitize Cells to Lysosomal Cell Death Induced by Inhibitors of Acid Sphingomyelinase

“Lysosomal membrane permeabilization and subsequent cell death may prove useful in cancer treatment, provided that cancer cell lysosomes can be specifically targeted. Here, we identify acid sphingomyelinase (ASM) inhibition as a selective means to destabilize cancer cell lysosomes. Lysosome-destabilizing experimental anticancer agent siramesine inhibits ASM by interfering with the binding of ASM to its essential lysosomal cofactor, bis(monoacylglycero)phosphate. Like siramesine, several clinically relevant ASM inhibitors trigger cancer-specific lysosomal cell death, reduce tumor growth in vivo, and revert multidrug resistance. Their cancer selectivity is associated with transformation-associated reduction in ASM expression and subsequent failure to maintain sphingomyelin hydrolysis during drug exposure. Taken together, these data identify ASM as an attractive target for cancer therapy.”


Cancer Cell – Transformation-Associated Changes in Sphingolipid Metabolism Sensitize Cells to Lysosomal Cell Death Induced by Inhibitors of Acid Sphingomyelinase

“Lysosomal membrane permeabilization and subsequent cell death may prove useful in cancer treatment, provided that cancer cell lysosomes can be specifically targeted. Here, we identify acid sphingomyelinase (ASM) inhibition as a selective means to destabilize cancer cell lysosomes. Lysosome-destabilizing experimental anticancer agent siramesine inhibits ASM by interfering with the binding of ASM to its essential lysosomal cofactor, bis(monoacylglycero)phosphate. Like siramesine, several clinically relevant ASM inhibitors trigger cancer-specific lysosomal cell death, reduce tumor growth in vivo, and revert multidrug resistance. Their cancer selectivity is associated with transformation-associated reduction in ASM expression and subsequent failure to maintain sphingomyelin hydrolysis during drug exposure. Taken together, these data identify ASM as an attractive target for cancer therapy.”


Study Finds Genetic Mutation in CRPC

“The mutation occurs in the androgen-synthesizing enzyme 3βHSD1 in castration-resistant prostate cancer (CRPC), according to research published online today in Cell. This mutation enables the tumor to make its own supply of androgens, a hormone that fuels the growth of the prostate cancer. Prostate cancer requires a constant supply of androgens in order to sustain itself. The current standard of care for patients with metastatic prostate cancer is medical castration, the ability to interfere with the body’s production of testosterone (androgens) using medications that disrupt the process. Oftentimes, metastatic prostate cancer flourishes despite the lack of testosterone in the bloodstream, creating CRPC. These tumors are able to exist without the body’s supply of testosterone by creating androgens within the tumor cell; however, increased androgen synthesis has not yet been attributable to any known mutations. The Cleveland Clinic discovery shows that the 3βHSD1 mutation makes this enzyme hyperactive to create androgens.”


Epidermal EGFR Controls Cutaneous Host Defense and Prevents Inflammation

“The epidermal growth factor receptor (EGFR) plays an important role in tissue homeostasis and tumor progression. However, cancer patients treated with EGFR inhibitors (EGFRIs) frequently develop acneiform skin toxicities, which are a strong predictor of a patient’s treatment response. We show that the early inflammatory infiltrate of the skin rash induced by EGFRI is dominated by dendritic cells, macrophages, granulocytes, mast cells, and T cells. EGFRIs induce the expression of chemokines (CCL2, CCL5, CCL27, and CXCL14) in epidermal keratinocytes and impair the production of antimicrobial peptides and skin barrier proteins. Correspondingly, EGFRI-treated keratinocytes facilitate lymphocyte recruitment but show a considerably reduced cytotoxic activity against Staphylococcus aureus. Mice lacking epidermal EGFR (EGFRΔep) show a similar phenotype, which is accompanied by chemokine-driven skin inflammation, hair follicle degeneration, decreased host defense, and deficient skin barrier function, as well as early lethality. Skin toxicities were not ameliorated in a Rag2-, MyD88-, and CCL2-deficient background or in mice lacking epidermal Langerhans cells. The skin phenotype was also not rescued in a hairless (hr/hr) background, demonstrating that skin inflammation is not induced by hair follicle degeneration. Treatment with mast cell inhibitors reduced the immigration of T cells, suggesting that mast cells play a role in the EGFRI-mediated skin pathology. Our findings demonstrate that EGFR signaling in keratinocytes regulates key factors involved in skin inflammation, barrier function, and innate host defense, providing insights into the mechanisms underlying EGFRI-induced skin pathologies.”


Autophagy Sustains Mitochondrial Glutamine Metabolism and Growth of BRAFV600E-Driven Lung Tumors

“Autophagic elimination of defective mitochondria suppresses oxidative stress and preserves mitochondrial function. Here, the essential autophagy gene Atg7 was deleted in a mouse model of BRAFV600E-induced lung cancer in the presence or absence of the tumor suppressor TRP53. Atg7 deletion initially induced oxidative stress and accelerated tumor cell proliferation in a manner indistinguishable from Nrf2 ablation.. Compound deletion of Atg7 and Nrf2 had no additive effect suggesting that both genes modulate tumorigenesis by regulating oxidative stress, revealing a potential mechanism of autophagy-mediated tumor suppression. At later stages of tumorigenesis, Atg7 deficiency resulted in an accumulation of defective mitochondria, proliferative defects, reduced tumor burden, conversion of adenomas and adenocarcinomas to oncocytomas, and increased mouse lifespan. Autophagy-defective tumor-derived cell lines were impaired in their ability to respire, survive starvation and were glutamine-dependent, suggesting that autophagy-supplied substrates from protein degradation sustains BRAFV600E-tumor growth and metabolism.”


Gleason Grade Progression Is Uncommon

“Gleason grade is universally used for pathologic scoring of the differentiation of prostate cancer. However, it is unknown whether prostate tumors arise well differentiated and then progress to less differentiated forms or if Gleason grade is an early and largely unchanging feature. Prostate-specific antigen (PSA) screening has reduced the proportion of tumors diagnosed at advanced stage, which allows assessment of this question on a population level. If Gleason grade progresses as stage does, one would expect a similar reduction in high-grade tumors. We studied 1,207 Physicians’ Health Study and Health Professionals Follow-up Study participants diagnosed with prostate cancer from 1982 to 2004 and treated with prostatectomy. We compared the distribution of grade and clinical stage across the pre-PSA and PSA screening eras. We re-reviewed grade using the ISUP 2005 revised criteria. The proportion of advanced stage tumors dropped more than six-fold, from the earliest period (12/1982–1/1993), 19.9% stage ≥T3, to the latest (5/2000–12/2004), 3% stage T3, none T4. The proportion of Gleason score ≥8 decreased substantially less, from 25.3% to 17.6%. A significant interaction between stage and diagnosis date predicting grade (P = 0.04) suggests that the relationship between grade and stage varies by time period. As the dramatic shift in stage since the introduction of PSA screening was accompanied by a more modest shift in Gleason grade, these findings suggest that grade may be established early in tumor pathogenesis. This has implications for the understanding of tumor progression and prognosis, and may help patients diagnosed with lower grade disease feel more comfortable choosing active surveillance.”