Current Areas of Research

1. Identification of Tumor primordial cells in colorectal cancers
2. CKS1; Validation of a new molecular target in cancer therapeutics
3. Investigation of functional role of CKS1 in oral tumor initiation and progression
4. Molecular Profiling of SMURF2 in Breast cancer
5. Peroxisomal Proliferator- Activated Receptor γ (PPAR γ), role as a Breast Cancer promoter or tumor inhibitor?
6. In vitro studies of novel sensitizers for photodynamic therapy

Tumor primordial cells in colorectal cancer: implications for surgical margins and minimal residual disease

Stem cell biology is one of the most exciting research topics of today. Although there is increasing evidence that a rare population of undifferentiated cells is responsible for tumour formation and maintenance this has not been explored in detail for colorectal cancer. The aim of our study is to identify, isolate, and characterize the cancer stem cell (CSC) population that drives and maintains colorectal cancer growth and metastasis. We will also analyze whether established malignant colon cancer cell lines, which have been maintained for years in culture, contain a side population (SP) of stem cells and study its characteristics at the molecular level. Similarly the potential role of these tumor primordial cells in surgical margins will be analyzed if any and correlated with the disease outcome. The identification of molecules expressed in the small subpopulation of cells that are at risk of becoming cancerous and the selective targeting of these cells that are pivotal for the growth of the entire tumor mass should not only lead to the more efficient elimination of this crucial population of cancer cells but also open new avenues to the development of more effective cancer therapies

CKS1; Validation of a new molecular target in cancer therapeutics

Molecular mechanism through which a drug elicits the desired response is primarily based on the elucidation and exploitation of biological, pharmacological, and biochemical mechanisms that have not been previously recognized or fully understood. Fluoxetine, a well-known antidepressant used clinically for mental depression has gained attention in cancer research owing to its chemosensitizing potential. Few reports have suggested its cytotoxic nature in prostate cancer and Burkitt’s lymphoma cells. It has also been reported to act as a differentiation inducer in neuronal cells. We aimed at characterizing its anticancer potential and to further elucidate the mechanism of action. Both cervical cancer (SiHa) and breast cancer cells (MDA MB 231) were used for the study. IC50 values of 28 µM and 32 µM were obtained for fluoxetine mediated antiproliferative response in these cells. Further, PARP and caspase 3 cleavage analyses confirmed fluoxetine mediated apoptosis at molecular level. Cell cycle analysis showed that fluoxetine arrested cells at G0/G1 phase in a time dependent manner. Application of bioinformatics tools at this juncture predicted cks1 as one of the possible targets of fluoxetine, which is of relevance to cell cycle biology. Therefore application of this newly discovered observation can be exploited for therapeutic benefit.

Investigation of functional role of cyclin dependant kinase subunit 1 (cks1) in oral tumor initiation and progression

The Cks family is composed of small proteins (9–18 kDa) that perform essential, conserved functions in the cell cycle. It was initially identified as a component of cyclin-cdk complexes and further studies have revealed that it serves as an accessory protein in the SCFSkp2 ubiquitinating machinery which is responsible for the proteasomal degradation of p27. Importantly, recent studies have reported cks1 over-expression in gastric, lung, oral and colorectal carcinomas contributing poor prognostic values. Though, cks1 over-expression was well correlated with reduced p27 levels in gastric and colorectal carcinomas such correlation was poor in non-small cell lung carcinoma in spite of its higher mRNA and protein levels. Moreover, most of the genetic and biochemical data generated in lower eukaryotes point to mitotic roles for cks proteins. Moreover, cks1 depletion in H358 lung cancer cells resulted in decreased cdk1 activity and a moderate accumulation of cells at G2-M phase. Thus the likelihood of occurrence of cks1 abnormality in mediating a disrupted mitotic phase and thereby tumor initiation and progression is higher and needs systematic investigation before profiling it as an ideal target for tumor diagnosis and management. Our study involves identification of functional importance of cks1 in mitosis promoting factor (MPF; cdk1/cyclinB) activation. Cdk1 is inactive during interphase due to phosphorylation at Thr-14 and Tyr-15 residues by wee1 and Myt1 kinases. Cdc25 phosphatase dephosphorylates these residues and activates the kinase. In addition, cdk1 needs binding with cyclin B and phosphorylation at Th-161 residue for its activity. We tend to investigate the role of cks1 in these cellular processes.

Molecular Profiling of SMURF2 in Breast cancer

Controlled protein degradation mediated by ubiquitin/proteasome system (UPS) plays a crucial role in modulating a broad range of cellular responses. Dysregulation of the UPS often accompanies tumorigenesis and progression. Ubiquitination of a target protein involves a cascade of enzymes. Importantly, E3 ubiquitin ligases determine the specificity of protein substrates and are themselves the enzymes. They, therefore represent a group of attractive and potentially "drugable" molecular targets for disease intervention in mechanism driven drug discovery. My work is to identify the expression and activation status of Smurf2 (Smad ubiquitin regulatory factor 2), a HECT-type E3-ubiquitin ligase and the signaling pathways in which they are involved in breast cancer and to further investigate whether inhibition of Smurfs by either plant derived or synthetic drugs could be an effective therapeutic regime in breast cancer. We analyzed the expression of Smurf2 in 7 breast cancer cell lines and a high level expression of Smurf2 was detected in MDA-MB-231, NCI-ADR-RES and SKBR3 cell lines.

Peroxisomal Proliferator Activated Receptor γ (PPAR γ), a tumor promoter or tumor inhibitor- Investigation of new perspectives in Breast Cancer

Based on the over expression of PPARγ in various forms of malignant diseases, several in vitro activation studies by specific ligands have been conducted and anticancer activity reported. But clinical trials reported few encouraging results on its efficacy in the clinics in comparison with its greater efficacy in the so called in vitro experiments. The PPARγ dependant specific effect on tumors is still unknown. From the previous studies, it is clear that the expression pattern of PPARγ is specific to a cancer type and some conflicting reports are also documented on its expression pattern in the same type of cancer and left without proper justification. In an animal study, it was shown that activation of PPARγ promotes tumor formation in mammary gland. This result suggests that, once an initiating event has taken place, increased PPARγ signaling may serve as a tumor promoter in the mammary gland. Thus a broad study on all the aspects of PPARγ in a specific cancer type should be studied well in order to define its effects on individual cancers.

In vitro studies of novel sensitizers for photodynamic therapy

Today, therapy of cancer often involves multiple treatments, combining the available options with the aim of achieving the optimal response. We believe that PDT will improve this optional response and is of utmost importance to the future of cancer therapy. After PDT treatment, subsequent treatments are possible, if required. Such repeat therapy is at best limited and often impossible with surgery and radiation therapy. Not only do we envisage PDT being used together with existing treatments, but also as a first-line treatment for some cancers where today's treatment options are inadequate or where no treatment option currently exists. The studies on PDT have also shown that cellular immune modulatory effects can be achieved in the absence of killing, thus expanding the potential applications of PDT to completely new fields.

Collaborations

1. Cancer Stem Cell Study
   • Prof. M.Radhakrishna Pillai, RGCB.
   • Dr. Chandramohan.K
   • Associate Professor, Division of Surgical Oncology
   • Regional Cancer Centre
2. PPARγ in Breast Cancer
   • Dr.Jem Prabhakar
   • Additional professor, Division of Surgical Oncology
   • Regional Cancer Centre
3. NIR dyes in Photodynamic Therapy
   • Professor M.Radhakrishna Pillai , RGCB,
   • Dr.D. Ramaiah,
   • National Institute for Interdisciplinary Science & Technology (NIIST), Trivandrum
   • Dr. Mohan Rao,
   • CCMB, Hyderabad
4. CKS1in oral carcinogenesis
   • Dr. Susanne M Gollin
   • Dept. of Human Genetics
   • University of Pittsburgh Cancer Institute, PA, USA