Basal cell carcinoma (BCC) of the skin is driven by aberrant hedgehog signaling. Thus blocking this signaling pathway by small molecules such as vismodegib inhibits tumor growth. Primary cilium in the epidermal cells plays an integral role in the processing of hedgehog signaling-related proteins. Recent genomic studies point to the involvement of additional genetic mutations that might be associated with the development of BCCs, suggesting significance of other signaling pathways, such as WNT, NOTCH, mTOR, and Hippo, aside from hedgehog in the pathogenesis of this human neoplasm. Some of these pathways could be regulated by noncoding microRNA. Altered microRNA expression profile is recognized with the progression of these lesions. Stopping treatment with Smoothened (SMO) inhibitors often leads to tumor reoccurrence in the patients with basal cell nevus syndrome, who develop 10–100 of BCCs. In addition, the initial effectiveness of these SMO inhibitors is impaired due to the onset of mutations in the drug-binding domain of SMO. These data point to a need to develop strategies to overcome tumor recurrence and resistance and to enhance efficacy by developing novel single agent-based or multiple agents-based combinatorial approaches. Immunotherapy and photodynamic therapy could be additional successful approaches particularly if developed in combination with chemotherapy for inoperable and metastatic BCCs.

Dihydropyrimidines are the most important heterocyclic ring systems which play an important role in the synthesis of DNA and RNA. Synthetically they were synthesized using Multi-component reactions like Biginelli reaction and Hantzschdihydropyridine. In the past decades, such Biginelli type dihydropyrimidones have received a considerable amount of attention due to the interesting pharmacological properties associated with this heterocyclic scaffold. In this review, we highlight recent developments in this area, with a focus on the DHPMs, recently developed as anti-inflammatory, anti-HIV, anti-tubercular, antifungal anticancer, antibacterial, antifilarial, antihyperglycemic, antihypertensive, analgesic, anti-convulsant, antioxidant, anti-TRPA1, anti-SARS, and anti-cancer activity and α binding affinity.

Arsenic exposure is known to disrupt innate immune functions in humans and in experimental animals. In this study, we provide a mechanism by which arsenic trioxide (ATO) disrupts macrophage functions. ATO treatment of murine macrophage cells diminished internalization of FITC-labeled latex beads, impaired clearance of phagocytosed fluorescent bacteria and reduced secretion of pro-inflammatory cytokines. These impairments in macrophage functions are associated with ATO-induced unfolded protein response (UPR) signaling pathway characterized by the enhancement in proteins such as GRP78, p-PERK, p-eIF2α, ATF4 and CHOP. The expression of these proteins is altered both at transcriptional and translational levels. Pretreatment with chemical chaperon, 4-phenylbutyric acid (PBA) attenuated the ATO-induced activation in UPR signaling and afforded protection against ATO-induced disruption of macrophage functions. This treatment also reduced ATO-mediated reactive oxygen species (ROS) generation. Interestingly, treatment with antioxidant N-acetylcysteine (NAC) prior to ATO exposure, not only reduced ROS production and UPR signaling but also improved macrophage functions. These data demonstrate that UPR signaling and ROS generation are interdependent and are involved in the arsenic-induced pathobiology of macrophage. These data also provide a novel strategy to block the ATO-dependent impairment in innate immune responses.

The biguanide metformin is widely used for the treatment of type II diabetes. Its anti-proliferative and pro-apoptotic effects in various tumor cells suggest its potential candidacy for cancer chemoprevention. Here we report that metformin significantly inhibited human epidermoid A431 tumor xenograft growth in nu/nu mice, which was associated with a significant reduction in proliferative biomarkers PCNA and cyclins D1/B1. This tumor growth reduction was accompanied by the enhanced apoptotic cell death and an increase in Bax:Bcl2 ratio. The mechanism by which metformin manifests anti-tumor effects appears to be dependent on the inhibition of nuclear factor kappa B (NFkB) and mTOR signaling pathways. Decreased phosphorylation of NFkB inhibitory protein IKBα together with reduced enhancement of NFkB transcriptional target proteins, iNOS/COX-2 were observed. In addition, a decrease in the activation of ERK/p38-driven MAP kinase signaling was seen. Similarly, AKT signaling activation as assessed by the diminished phosphorylation at Ser473 with a concomitant decrease in mTOR signaling pathway was also noted as phosphorylation of mTOR regulatory proteins p70S6K and 4E-BP-1 was significantly reduced. Consistently, decreased phosphorylation of GSK3β which is carried out by AKT kinases was also observed. These results suggest that metformin blocks SCC growth by dampening NFkB and mTOR signaling pathways.

Arsenic exposure through drinking water is a major global public health problem and is associated with an enhanced risk of various cancers including skin cancer. In human skin, arsenic induces precancerous melanosis and keratosis, which may progress to basal cell and squamous cell carcinoma. However, the mechanism by which these pathophysiological alterations occur remains elusive. In this study, we showed that sub-chronic arsenic exposure to SKH-1 mice induced unfolded protein response (UPR) signaling regulated by proteins, inositol-requiring enzyme-1 (IRE1), PKR-like endoplasmic reticulum kinase (PERK) and activating transcription factor 6 (ATF6). Arsenic activated all three UPR regulatory proteins in the skin. Arsenic induced IRE1 phosphorylation which resulted in augmented splicing of X-box binding protein 1 (XBP-1) leading to its migration to the nucleus, and also enhanced transcriptional activation of downstream target proteins. Hyperphosphorylation of PERK which induces eukaryotic translation initial factor 2 α (eIF2α) in a phosphorylation-dependent manner enhanced translation of ATF4, in addition to augmenting proteolytic activation of ATF6 in arsenic-treated skin. A similar increase in the expression of CHOP was observed. Enhanced XBP-1s, ATF4 and ATF6 regulated downstream chaperones GRP94 and GRP78. Additionally, arsenic induced inflammation-related p38/MAPKAPK-2 MAPK signaling and alterations in Th-1/Th-2/Th-17 cytokines/chemokines and their receptors. Antioxidant N-acetyl cysteine blocked arsenic-induced reactive oxygen species, with a concomitant attenuation of UPR and MAPK signaling and pro-inflammatory cytokine/chemokine signatures. Our results identify novel pathways involved in the pathogenesis of arsenic-mediated cutaneous inflammation which may also be related to enhanced cancer risk in arsenic exposed cohorts.