Locus of fragility in robust breast cancer system

Harnessing cancer cell metabolism for theranostic applications using metabolic glycoengineering of sialic acid in breast cancer as a pioneering example

Abnormal cell surface display of sialic acids - a family of unusual 9-carbon sugars - is widely recognized as distinguishing feature of many types of cancer. Sialoglycans, however, typically cannot be identified with sufficiently high reproducibility and sensitivity to serve as clinically accepted biomarkers and similarly, almost all efforts to exploit cancer-specific differences in sialylation signatures for therapy remain in early stage development. In this report we provide an overview of important facets of glycosylation that contribute to cancer in general with a focus on breast cancer as an example of malignant disease characterized by aberrant sialylation. We then describe how cancer cells experience nutrient deprivation during oncogenesis and discuss how the resulting metabolic reprogramming, which endows breast cancer cells with the ability to obtain nutrients during scarcity, constitutes an "Achilles' heel" that we believe can be exploited by metabolic glycoengineering (MGE) strategies to develop new diagnostic methods and therapeutic approaches. In particular, we hypothesize that adaptations made by breast cancer cells that allow them to efficiently scavenge sialic acid during times of nutrient deprivation renders them vulnerable to MGE, which refers to the use of exogenously-supplied, non-natural monosaccharide analogues to modulate targeted aspects of glycosylation in living cells and animals. In specific, once non-natural sialosides are incorporated into the cancer "sialome" they can be exploited as epitopes for immunotherapy or as chemical tags for targeted delivery of imaging or therapeutic agents selectively to tumors.

AKT as locus of cancer multidrug resistance and fragility

Complexity and robustness of cancer hypoxic microenvironment are supported by the robust signaling networks of autocrine and paracrine elements creating powerful interactome for multidrug resistance. These elements generate a positive feedback loops responsible for the extreme robustness and multidrug resistance in solid cancer, leukemia, myeloma, and lymphoma. Phosphorylated AKT is a cancer multidrug resistance locus. Targeting that locus by oxidant/antioxidant balance modulation, positive feedback loops are converted into negative feedback loops, leading to disappearance of multidrug resistance. This is a new principle for targeting cancer multidrug resistance by the locus chemotherapy inducing a phenomenon of loops conversion.

AKT as locus of cancer positive feedback loops and extreme robustness

A positive feedback loops induce extreme robustness in metastatic cancer, relapsed leukemia, myeloma or lymphoma. The loops are generated by the signaling interactome networks of autocrine and paracrine elements from cancer hypoxic microenvironment. The elements of the networks are signaling proteins synthesized in hypoxic microenvironment such as the vascular endothelial growth factor, HIF-1α, hepatocyte growth factor, and molecules nitric oxide and H(2)O(2). The signals from upstream or rebound downstream pathways are amplified by the short or wide positive feedback loops, hyperstimulating AKT-inducing cancer extreme robustness. Targeting the phosphorylated AKT locus by an oxidant/antioxidant modulation induces collapse of positive feedback loops and establishment of negative feedback loops leading to stability of the system and disappearance of cancer extreme robustness. This is a new principle for the conversion of cancer positive loops into negative feedback loops by the locus chemotherapy.

Increased angiogenesis-associated poor outcome in acute lymphoblastic leukemia: a single center study

Angiogenesis in solid tumors is important for tumor growth, invasion, and metastasis. However, angiogenesis plays also an important role in hematological malignancies. We have analyzed the expression of vascular endothelial growth factor (VEGF) in the leukemic blast cells and microvessel density (MVD) in the bone marrow biopsy samples of the patients with acute lymphoblastic leukemia (ALL). Bone marrow MVD of the patients with ALL was significantly higher compared with normal controls and complete remission (P<0.001), but slightly lower than in patients with relapsed ALL (P>0.05). The bone marrow blast VEGF expression was significantly higher in newly diagnosed ALL patients, with predominant strong VEGF expression as compared with complete remission patients (who had negative or weak VEGF expression) (P<0.05), whereas initial values were slightly lower than in relapsed patients. There was a strong positive correlation between VEGF expression and MVD at presentation of ALL. Stronger expression of VEGF on blast cells indicates shorter overall survival in ALL. Furthermore, initial values of MVD had positive correlation with overall survival and leukemia-free survival (P=0.024 and P=0.017, respectively). Our data suggest that increased angiogenesis (confirmed by immunohistochemical expression of VEGF in leukemic blasts), and MVD may play an important role in the pathophysiology of ALL with prognostic implications. Thus, targeting VEGF pathway may bring the new approach for ALL treatment-using antiangiogenic drugs and tyrosine kinase inhibitors in combination with standard chemotherapy regimens.

AKT as locus of cancer angiogenic robustness and fragility

Angiogenesis get full robustness in metastatic cancer, relapsed leukemia or lymphoma when complex positive feedback loop signaling systems become integrative. A cancer hypoxic microenvironment generates positive loops inducing formation of the vascular functional shunts. AKT is an upstream angiogenic locus of integrative robustness and fragility activated by the positive loops. AKT controls two downstream nodes the mTOR and NOS in nodal organization of the signaling genes. AKT phosphorylation is regulated by a balance of an oxidant/antioxidant. Targeting AKT locus represents new principle to control integrative angiogenic robustness by the locus chemotherapy.

Inhibition of activated receptor tyrosine kinases by Sunitinib induces growth arrest and sensitizes melanoma cells to Bortezomib by blocking Akt pathway

Despite the use of multiple therapeutic strategies, metastatic melanoma remains a challenge for oncologists. Thus, new approaches using combinational treatment may be used to try to improve the prognosis of this disease. In this report, we have analyzed the expression of receptor tyrosine kinases (RTKs) in melanoma specimens and in four metastatic melanoma cell lines. Both melanoma specimens and cell lines expressed RTKs, suggesting that they may represent eventual targets for multitargeted tyrosine kinase inhibitor, Suntinib. Sunitinib reduced the proliferation of two melanoma cell lines (M16 and M17) and increased apoptosis in one of them (M16). Moreover, the two metastatic melanoma cell lines harbored an activated receptor (PDGFRα and VEGFR, respectively), and Sunitinib suppressed the phosphorylation of the RTKs and their downstream targets Akt and ribosomal protein S6, in these two cell lines. Similar results were obtained when either PDGFRα or VEGFR2 expression was silenced by lentiviral-mediated short-hairpin RNA delivery in M16 and M17, respectively. To evaluate the interaction between Sunitinib and Bortezomib, median dose effect analysis using MTT assay was performed, and combination index was calculated. Bortezomib synergistically enhanced the Sunitinib-induced growth arrest in Sunitinib-sensitive cells (combination index < 1). Moreover, LY294002, a PI3K inhibitor, sensitized melanoma cells to Bortezomib treatment, suggesting that downregulation of phospho-Akt by Sunitinib mediates the synergy obtained by Bortezomib + Sunitinib cotreatment. Altogether, our results suggest that melanoma cells harboring an activated RTK may be clinically responsive to pharmacologic RTK inhibition by Sunitinib, and a strategy combining Sunitinib and Bortezomib, may provide therapeutic benefit.