Recently, researchers have developed a new approach to block the KRAS oncogene, one of the most frequently mutated genes in human cancer. The approach relies upon siRNA to attack KRAS, which is tantalizing yet elusive target for drug developers.

The findings, published in the journal Molecular Cancer Therapeutics, show that using a form of siRNA to halt KRAS not only dramatically stunted the growth of lung and colon cancers in cultured cells and mice but also blocked metastasis.

As known in the biomedical circle, KRAS is a signaling molecule — a protein switch that triggers a cascade of molecular events that tell cells to grow and survive. Mutations in the KRAS gene create a switch that is perpetually “on,” causing cells to divide uncontrollably. KRAS mutations are present in approximately 30% of human cancers, particularly lung, colon, pancreatic, and thyroid cancer.

Over the past decades, KRAS has been widely regarded as undruggable target, since it lacks good pockets or binding sites for small molecules and drug to bind to. Some researchers have tried instead to target the proteins downstream in the KRAS signaling cascade, but those attempts have also had limited success.

Instead of other conventional methods, a new genetic tool known as RNA interference (also called RNAi) is employed to destroy the KRAS protein before it fully forms. RNAi uses bits of synthetically engineered RNA to silence specific genes. These bits of RNA bind to specific genetic messages called mRNA in the cell and direct enzymes to recognize the messages as enemies. In this context, the enzymes destroyed the genetic messages of KRAS mRNA so that KRAS can’t be made. As a result, the cells don’t grow, replicate, or move nearly as well.

RNAi has shown great promise in the treatment of liver diseases, viral infections, and cancers. To see if this approach could thwart the KRAS oncogene, researchers had to test different sequences of RNA to determine which one most effectively tagged KRAS for destruction. Of five RNA sequences, the researchers identified two candidates worthy to take into cancer models.

When they delivered these sequences into tissue culture cells, they found that the siRNAs destroyed over 90% of the KRAS gene messages, significantly impairing the growth of cancer cell lines. The siRNA sequences will have to be designed to specifically target the mutant form of KRAS without disrupting the normal form of the gene, which is necessary for maintaining normal growth in healthy cells.

Reference:

Therapeutic Silencing of KRAS using Systemically Delivered siRNAs. Molecular Cancer Therapeutics, 2014

A new research indicated that the treatment with poly (ADP-ribose) polymerase (PARP) inhibitors, together with chemotherapy drugs, could be applied for RUNX leukemia. This study was published in Cell journal Reports.

Unlike other cancer is more common in the elderly, leukemia has a high incidence among young people. In recent years, the breakthrough treatment of the leukemia is few. According to the previous study, RUNX1 is one of the most frequent mutations of genes in leukemia. And RUNX3 is associated with the development of the disease.

The result showed that ablation of both Runx1 and Runx3 led to defective DNA repair. Recent technological advances have shown frequent deletions of chromosome 21q, including the RUNX1 locus, in patients with congenital syndromic thrombocytopenia with leukemia predisposition.

It is clearly demonstrated that human leukemia cell lines expressing the RUNX1-ETO fusion gene are sensitive to MMC, at least partially in a fusion gene-dependent manner. This sensitivity was further enhanced in the presence of PARP inhibitor. The treatment with PARP inhibitors, together with DNA ICL and/or standard chemotherapy drugs, could be applied for RUNX leukemia. Because deregulation in RUNX family genes is now found in a wide spectrum of cancers, this combined therapy can potentially be extended to common cancers.

PARP is found in the cell’s nucleus. The main role is to detect and signal single-strand DNA breaks (SSB) to the enzymatic machinery involved in the SSB repair. In this study, PARP play the imported role in the treatment of the leukemia, and it is the breakthrough treatment of the leukemia.

Reference:

CQ Wang, V Krishnan, et al. Disruption of Runx1 and Runx3 Leads to Bone Marrow Failure and Leukemia Predisposition due to Transcriptional and DNA Repair Defects [J].Cell reports 2014, 8(3): 767–782.

Researchers from Johns Hopkins University have developed a new device which could monitor the metastasis of breast cancer cells. This finding allows scientists to watch and record the behaviour of cancer cells as they burrow through tissue, infiltrate blood vessels, and enter the blood stream to travel quickly and easily through the body. The study was published in Cancer Research.

More than 90 percent of cancer-related deaths are caused by metastatic cancer cells spreading around the body, however until now, scientists haven’t been able to get a good, clear look at this complicated process.

In this study, A special nutrient-rich solution was injected into the chip and made to flow through the artificial blood vessel. Then, the researchers inserted individual and clustered human breast cancer cells into the artificial tissue. The breast cancer cells were labelled with fluorescent tags so they could be easily tracked and recorded. In the tests, the artificial tissues acted like human tissue does in an actual cancer patient, which could be monitored.

The device offered such a detailed view for the scientists to observe a single cancer cell as it located a weak spot in the lining of the blood vessel, exerted enough pressure on it to break through, and then squeezed itself in far enough to be taken up by the bloodstream. Another advantage is that the cancer migration process can be viewed countless times without invasive procedures being carried out on actual cancer patients.

Generally, this device allows researchers to look at the major steps of metastasis as well as to test different treatment strategies at relatively fast pace. If one way to stop one of these steps in the metastatic is cascaded, a new strategy may be found to slow down or even the spread of cancer.

Metastasis is thought to be the main cause of cancer death. However, it has been slow in the process of preventing and treating migratory cancer cells.  A research team from Harvard Medical School has identified that an overabundance of a cell receptor named Frizzled-2, along with its activator, Wnt5, appears to raise a tumor’s likelihood of metastasizing. It could trigger the process known as the epithelial-mesenchymal transition(EMT). Their study may help researchers better understand how metastasis begins and inform the design of new treatments to combat it. This finding was published in Cell.

EMT generally plays a role in human development, allowing specific cells to become mobile and invasive. Then, they would move around and form new structures in the growing embryo. Previous researches have linked EMT to cancer metastasis, where tumor cells acquire those properties to disastrous effect. Nevertheless, the mechanism of this progress is still unknown.

In this study, scientists focus on the question “what makes one type of tumor metastasize and another type not?” and discovered a brand-new cell signaling pathway on the basic biology level.

After learning the importance of Frizzled-2, they also developed an antibody to block it . The antibody could curb metastasis in mice with certain type of tumors. In addition, frizzled-2 provides a promising new therapeutic target to prevent or delay metastasis, and both Frizzled-2 and Wnt5 are potential biomarkers that can be used to identify which patients are most at risk of metastasis and could benefit from frizzled-2-directed therapy.

They also found that Wnt and its receptor, Frizzled-2, were present at higher than normal levels in metastatic liver, breast, lung and colon cancer cell lines. In tissue samples from 48 cancer patients, Frizzled-2 was higher in late-stage cancers than in early-stage cancers. The team then painstakingly pieced together the players linking Wnt5 with the onset of metastatic behavior and discovered a previously unknown Wnt pathway. Frizzled-2 it turned out , could activate STAT3, which is known to drive cancer through.

The researchers are confident that their discovery can be translated into a novel therapeutic option for patients in the future.

Reference:

Gujral T S, Chan M, Peshkin L, et al. A Noncanonical Frizzled2 Pathway Regulates Epithelial-Mesenchymal Transition and Metastasis[J]. Cell, 2014, 159(4): 844-856.

A resent research reported the comprehensive genomic characterization of squamous cell lung cancers.

Targeted kinase inhibitors have been successfully used for the treatment of lung adeno carcinoma but minimally so in lung SQCC. The observations reported here suggest that a detailed understanding of the possible targets in lung SQCCs may identify targeted therapeutic approaches. Whereas EGFR and KRAS mutations, the two most common oncogenic aberrations in lung adenocarcinoma, are extremely rare in lung SQCC, alterations in the FGFR kinase family are common. Lung SQCCs also share many alterations in common with head and neck squamous cell carcinomas without evidence of human papilloma virus infection, including mutation in PIK3CA,PTEN, TP53, CDKN2A, NOTCH1 and HRAS, suggesting that the biology of these two diseases may be similar.

The current study has identified a potentially targetable gene or pathway alteration in most lung SQCC samples studied. The data presented here can help to organize efforts to analyse lung SQCC clinical tumour specimens for a panel of specific, actionable mutations to select patients for appropriately targeted clinical trials. These data could thereby help to facilitate effective personalized therapy for this deadly disease.

In a study published online on 23 October inCancer Cell, researchers show that when human breast-cancer exosomes can cause tumours when mixed with normal cells then injected into mice. The results could pave the way to finding markers to monitor the progression of cancer, and possibly even point to targets for therapies.

The team also collected exosomes from the blood of 8 healthy individuals and 11 people with breast cancer. Five of the 11 exosome samples from the patients induced tumour growth when mixed with normal cells and injected into mice; none of the exosome samples from healthy people did so.

It is unclear how far exosomes can travel in the body, says Kalluri, but the fact that the team could isolate them from blood suggests that they could be quite mobile. And even if their effect is only local, they could still make nearby cancer cells more aggressive, or transform healthy cells into cancerous ones, he says.

But trying to slow cancer by blocking exosomes is a difficult proposition, says Al-Nedawii. It is unclear how that would affect normal cells, he notes, and some exosomes from healthy cells have been shown to contain proteins that prevent cancer.

A more imminent application might be to use exosomes as a way to detect and monitor cancer, he adds. Kalluri notes that exosomes are more abundant and easier to isolate than tumour cells floating in the blood, which have also been used to track disease. “There are millions of exosomes being made by each cell,” he says. “That’s very powerful.”

Reference

Cancer cells can ‘infect’ normal neighbours, Nature ︱ doi:10.1038/nature.2014.1621

 Research from Aeyung Kim and Minju Im shows that Suppression of MMP-9 activity and VEGF production resulting in reduction of metastatic and angiogenic potency of malignant cancer by Eupatorium fortunei.

In this study, they used CM from tumor cells as an inducer to stimulate endothelial cells for an in vitro angiogenesis assay to mimic in vivo tumor-induced angiogenesis. As reported by Ito et al, they observed that CM from HT1080 cells promoted the growth of HUVECs and increased tube formation on Matrigel. In contrast, WEF-treated tumor cells showed decreased production of MMP-9 in the CM; consequently, proteolytic activity against gelatin and collagen, and migration/invasion through Matrigel by WEF-treated cells were lower than those by control cells. WEF also inhibited the production of VEGF-α by tumor cells, thereby suppressing tumor-induced capillary-like tube formation and HUVEC migration. Furthermore, WEF-treated CM suppressed sprouting in an ex vivoaortic ring assay. In a Matrigel plug assay, the WEF-containing tumor xenograft showed not only a significant reduction in growth, but also decreased neovascularization, supporting the in vivo anti-angiogenic potency of WEF. WEF had no direct effect on endothelial cells in terms of migration, tube formation, or angiogenesis. Collectively, these results suggest that WEF has anti-metastatic and anti-angiogenic potency, targeting cancer cells but not endothelial cells.

In response to PMA stimulation, MAPK activation and subsequent NF-κB activation occurred, resulting in MMP-9 activation, which is involved in cancer cell adhesion, invasion, and angiogenesis. In this study, they found that WEF almost completely blocked PMA-induced p38 and JNK phosphorylation, and dramatically decreased PMA-induced NF-κB activation, consequently suppressing cellular metastatic potential by down regulating MMP-9 activity. PC-3 and HT1080 cells also produced high levels of VEGF under normoxic conditions, and WEF inhibited VEGF expression. Under hypoxic conditions, PC-3 and HT1080 cells accumulated HIF-1α, which activates VEGF expression by binding the hypoxia response element in the VEGF promoter region, and which plays a pivotal role in tumor adaptation to the microenvironment. It has been reported that HIF-1α is overexpressed in many human cancers and their metastatic foci, and it correlates with increased vessel density and resistance to chemo/radiotherapy. Thus, factors that regulate HIF-1α activity are potential targets for cancer treatment. As shown in Figures 1, WEF inhibited hypoxia-induced HIF-1α accumulation by suppressing Akt/mTOR signaling, supporting the finding that WEF inhibited PC-3 tumor xenograft growth and angiogenesis in nude mice (Figures 1).

In summary, their data indicate that WEF exerted anti-metastatic and anti-angiogenic effects on malignant cancer cells both in vitro and in vivo by targeting key molecules involved in tumor progression, including MMP-9 and VEGF. Furthermore, they observed the potent therapeutic efficacy of WEF against pulmonary metastasis in mice, with no apparent side effects. These results indicate that WEF may be a candidate agent against malignant metastatic human cancers.

Reference

Aeyung Kim, Minju Im, Nam-Hui Yim and Jin Yeul Ma, Reduction of metastatic and angiogenic potency of malignant cancer by Eupatorium fortunei via suppression of MMP-9 activity and VEGF production, Scientific Reports 4, Article number:6994︱doi:10.1038/srep06994

Research from Yu-Chuan Hu and Lang Wu shows that several variables which are largely unreported before, including degree of CT enhancement, risk of aggressiveness, and multiple nodule with fibrous septum could preoperatively help determine the WHO pathological classification of TETs patients, especially for the low risk and high risk subtypes.

In this study, they employed the largest cohort of TETs patients up to date to investigate whether CT diagnostic parameters could identify staging of this cancer. The conventional CT findings can determine tumor size, shape, density, involvement of the capsule and surrounding tissues, all of which are related to the WHO histologic classification and clinical stages of TETs. In their study, a greater average tumor diameter indicates a higher probability that the tumor is malignant. It is very often for thymic carcinoma to have a maximum diameter of larger than 8 cm (49.1%). Low risk thymic tumors (types A, AB) are often round or oval with a clear, smooth margin, complete capsule and homogenous density; on the contrary, high risk subtypes (types B1, B2, B3 and thymic carcinoma) are often irregular in shape or deep lobulated. There is usually a higher rate of invasion by direct extending to adjacent structures including pericardium, large vessels or lung. The lobulation rate is bettheyen 60% and 89% based on previous study. Focusing on common CT manifestation parameters, they detected that size, boundary, capsule, homogeneity, septa, necrotic or cystic change, pleural effusion, lymphadenopathy, and invasion of adjacent tissues demonstrated significant differences among the 6 TETs subtypes, which confirms previous findings. However, there was no significant difference for tumor shape among the different pathological types of TETs (P = 0.206), which is inconsistent with previous studies. The finding that there was no significant difference for calcification among the different pathological types of TETs (P = 0.474) confirms the conclusion from a previous systematic review.

CT enhancement is very often used in TETs diagnosis since it can better reveal the tumor shape and invasion to adjacent tissues, as theyll as demonstrate the blood supply to tumor tissues. For the first time, they demonstrated that significantly different degrees of CT enhancement exist for different TETs WHO classifications. The area under the ROC curve for differentiating low (types A, AB) from high risk subtypes (types B1 B2, B3 and thymic carcinoma) reaches 80%. And the best cutting point for CE_max is at 25.5 HU, when the sensitivity and specificity of determining low risk subtypes are 78.8% and 68.5%, respectively. Generally speaking, degree of CT enhancement may represent levels of blood supply, thus should increase with more advanced tumor stages. Research has indicated a significant correlation bettheyen tumor angiogenesis and invasiveness in patients with TETs. However, their finding is out of expectation in suggesting that low risk subtype of thymoma (type A and AB) demonstrated a high degree of CT enhancement while high risk ones demonstrated a much lotheyr degree of CT enhancement. Pan et al studied the clinicopathologic characteristics of spindle cell thymoma (medullary, WHO type A) and mixed spindle/lymphocytic thymoma (WHO type AB), and found that the short-spindled pattern of type A thymoma may commonly arrange in a hemangiopericytic or microcystic pattern, which may explain why a higher degree of CT enhancement exist in low risk subtypes in their study. To the best of their knowledge, this exploration of degree of CT enhancement and stage of TETs has never been investigated before, and focusing on their clinical question itself, this interesting finding implies that degree of CT enhancement can probably predict the classifications of TETs.

The Masaoka staging system has been widely used in the clinical management of TETs with the clinical stage remaining the most important prognostic factor of thymoma. A recent study demonstrated a close relationship bettheyen preoperative CT thymoma staging and postoperative Masaoka clinical staging. Based on CT demonstrations of pathological classifications and Masaoka stages of primary mediastinal tumor, they proposed a parameter of aggressive risk. In this comprehensive analysis of 216 TETs patients, they detected a strong correlation bettheyen CT grade of aggressive risk and WHO histological classification (r = 0.801, P < 0.001). Their data also suggested that such a parameter could potentially help differentiate low from high risk TET subtypes, which could potentially add confidence in such a determination besides the parameter of degree of CT enhancement.

Interestingly, in their study they detected that multiple nodule with fibrous septum appeared in over 77% of type AB thymomas, but was rare in other subtypes and if existed, with a different manifestation. Histologically, type AB thymoma shotheyd multiple nodules separated by fibrous bands. The multiple nodules with fibrous septum features on CT imaging are consistent with the macroscopic appearance of a type AB thymoma (Fig 1). However, high risk TET subtypes especially thymic carcinoma appear as mainly deep lobulation or spiculate protuberance without tumor septum (Fig 1). This finding is useful in determining type AB thymomas. The detection of tumor septum can potentially be useful as a marker for type AB thymoma.

Their study also has limitations to acknowledge. Firstly, they did not analyze CT characteristics of thymic carcinoma according to their specific pathological classifications. Certain subtypes of thymic carcinoma such as neuroendocrine carcinomas have differentiated CT manifestations and prognosis, which warrants further study. Secondly, the complete survival data of these patients are not available, which intimidates the possibility to determine the relationship bettheyen survival and variables of risk of aggressiveness and degree of CT enhancement. The fact that survival rates of TETs patients, especially for those in low risk subgroups, are relatively high and a very long follow up will be required to collect these data. Further study for elucidating this research question is warranted. Thirdly, the hemodynamic analysis of TETs based on histopathology was not conducted, and further study for resolving this research question will be needed to clarify the mechanism of CT enhancement finding in this study.

In conclusion, using the largest sample up to date, they identified that several variables which are largely unreported before, including degree of CT enhancement, risk of aggressiveness, and multiple nodule with fibrous septum could preoperatively help determine the WHO pathological classification of TETs patients, especially for the low risk and high risk subtypes. A combined prediction using these variables will provide a better guidance for appropriate therapeutic strategies for TETs patients.

According to Research presented at the National Cancer Research Institute (NCRI) Cancer Conference in Liverpool , researchers have found a possible way to halt Kras fault in many types of cancer, which earns a reputation in scientific circles as being ‘undruggable’.

A team of scientists from Germany has discovered a new strategy and new potential drug to target the important Ras protein in cell signalling, which is faulty in many types of cancer.  It can cause too many signals to be produced –leading to cancer, when lying in faulty versions. The researchers have shown that instead of directly targeting the faulty protein itself, they can stop it moving to the surface of the cell by blocking another protein which transports Ras — preventing it from triggering cancer in the first place.

Previously, Howard Hughes Medical Institute (HHMI) researchers at the University of California, had identified and exploited a Achilles heel” in K-Ras. The weak point is a newly discovered ‘pocket’ or binding site. They have designed a chemical compound that fits inside this pocket and inhibits the normal activity of mutant K-Ras, but leaves the normal protein untouched. The findings, published in the journal Nature, are promising to end the lasting 30-year history of ‘undruggable’ Kras.

A researcher, attending NCRI Cancer Conference, said: “We’ve been scratching our heads for decades to find a solution to one of the oldest conundrums in cancer research. And we’re excited to discover that it’s actually possible to completely bypass this cancer-causing protein rather than attack it directly.

Another researcher said, “The new approach can target one of the most common faults in cancer, which could give rise to another option of disease treatment. The research is still at a very early stage and it will be years before it can benefit patients but it is a key step forward in the field.”

Reference:

Small molecule inhibition of the KRAS–PDEδ interaction impairs oncogenic KRAS signalling. Nature 497, 638–642

Scientists from Cancer Research UK have discovered a new combination of drugs which could start the self-destructive process of lung cancer cells. This finding paves the way for the research on new lung cancer therapy. Their study was published in Cell Death & Differentiation.

Tumor necrosis factor-related apoptosis-inducing ligand(TRAIL) can induce apoptosis in many cancer cells without causing toxicity in vivo. However, to date, TRAIL-receptor agonists have only shown limited therapeutic benefit in clinical trials.

In this study, researchers have identified PIK-75, a small molecule inhibitor of the p110αisoform of phosphoinositide-3 kinase(PI3K) as an exceptionally potent TRAIL apoptosis sensitizer. However, PI3K inhibition was not responsible for this activity. A kinome-side in vitro screen revealed that PIK-75 strongly inhibits a panel of 27 kinases in addition to p110α. Within this panel, they identified with TRAIL effectively induced apoptosis even in highly TRAIL-resistant cancer cells. In addition, When evaluating cancer selectivity of TRAIL combined with SNS-032, the most selective and clinically used inhibitior of CDK9, they found that a panel of mostly TRAIL-resistant non-small cell lung cancer cell lines was readily killed, even at low concentrations of TRAIL.

To sum up, based on the high potency of CDK9 inhibition as a cancer cell-selective TRAIL-sensitizing strategy, the researchers envisage the development of new, highly effective cancer therapies.

Reference:

Lemke J, von Karstedt S, El Hay M A, et al. Selective CDK9 inhibition overcomes TRAIL resistance by concomitant suppression of cFlip and Mcl-1[J]. Cell Death & Differentiation, 2013, 21(3): 491-502.