Intranasal Administration of GRP78 Protein (HSPA5) Confers Neuroprotection in a Lactacystin-Induced Rat Model of Parkinson's Disease.

The accumulation of misfolded and aggregated α-synuclein can trigger endoplasmic reticulum (ER) stress and the unfolded protein response (UPR), leading to apoptotic cell death in patients with Parkinson's disease (PD). As the major ER chaperone, glucose-regulated protein 78 (GRP78/BiP/HSPA5) plays a key role in UPR regulation. GRP78 overexpression can modulate the UPR, block apoptosis, and promote the survival of nigral dopamine neurons in a rat model of α-synuclein pathology. Here, we explore the therapeutic potential of intranasal exogenous GRP78 for preventing or slowing PD-like neurodegeneration in a lactacystin-induced rat model. We show that intranasally-administered GRP78 rapidly enters the substantia nigra pars compacta (SNpc) and other afflicted brain regions. It is then internalized by neurons and microglia, preventing the development of the neurodegenerative process in the nigrostriatal system. Lactacystin-induced disturbances, such as the abnormal accumulation of phosphorylated pS129-α-synuclein and activation of the pro-apoptotic GRP78/PERK/eIF2α/CHOP/caspase-3,9 signaling pathway of the UPR, are substantially reversed upon GRP78 administration. Moreover, exogenous GRP78 inhibits both microglia activation and the production of proinflammatory cytokines, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), via the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway in model animals. The neuroprotective and anti-inflammatory potential of exogenous GRP78 may inform the development of effective therapeutic agents for PD and other synucleinopathies.

Novel mechanism of drug resistance triggered by tumor-associated macrophages through Heat Shock Factor-1 activation.

Macrophages constitute a major part of tumor microenvironment, and most of existing data demonstrate their ruling role in the development of anti-drug resistance of cancer cell. One of the most powerful protection system is based on heat shock proteins whose synthesis is triggered by activated Heat Shock Factor-1 (HSF1); the inhibition of the HSF1 with CL-43 sensitized A549 lung cancer cells to the anti-cancer effect of etoposide. Notably, analyzing A549 tumor xenografts in mice we observed nest-like pattern of co-localization of A549 cells demonstrating enhanced expression of HSF1 with macrophages, and decided to check whether the above arrangement has a functional value for both cell types. It was found that the incubation of A549 or DLD1 colon cancer cells with either human monocytes or THP1 monocyte-like cells activated HSF1 and increased resistance to etoposide. Importantly, the same effect was shown when primary cultures of colon tumors were incubated with THP1 cells or with human monocytes. To prove that HSF1 is implicated in enhanced resistance caused by monocytic cells, we generated an A549 cell subline devoid of HSF1 which did not respond to incubation with THP1 cells. The pharmacological inhibition of HSF1 with CL-43 also abolished the effect of THP1 cells on primary tumor cells, highlighting a new target of tumor-associated macrophages in a cell proteostasis mechanism.